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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
bf0f6f24 IM |
2 | /* |
3 | * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH) | |
4 | * | |
5 | * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
6 | * | |
7 | * Interactivity improvements by Mike Galbraith | |
8 | * (C) 2007 Mike Galbraith <efault@gmx.de> | |
9 | * | |
10 | * Various enhancements by Dmitry Adamushko. | |
11 | * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com> | |
12 | * | |
13 | * Group scheduling enhancements by Srivatsa Vaddagiri | |
14 | * Copyright IBM Corporation, 2007 | |
15 | * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> | |
16 | * | |
17 | * Scaled math optimizations by Thomas Gleixner | |
18 | * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de> | |
21805085 PZ |
19 | * |
20 | * Adaptive scheduling granularity, math enhancements by Peter Zijlstra | |
90eec103 | 21 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra |
bf0f6f24 IM |
22 | */ |
23 | ||
589ee628 | 24 | #include <linux/sched/mm.h> |
105ab3d8 IM |
25 | #include <linux/sched/topology.h> |
26 | ||
cb251765 | 27 | #include <linux/latencytop.h> |
3436ae12 | 28 | #include <linux/cpumask.h> |
83a0a96a | 29 | #include <linux/cpuidle.h> |
029632fb PZ |
30 | #include <linux/slab.h> |
31 | #include <linux/profile.h> | |
32 | #include <linux/interrupt.h> | |
cbee9f88 | 33 | #include <linux/mempolicy.h> |
e14808b4 | 34 | #include <linux/migrate.h> |
cbee9f88 | 35 | #include <linux/task_work.h> |
78634061 | 36 | #include <linux/sched/isolation.h> |
029632fb PZ |
37 | |
38 | #include <trace/events/sched.h> | |
39 | ||
40 | #include "sched.h" | |
9745512c | 41 | |
bf0f6f24 | 42 | /* |
21805085 | 43 | * Targeted preemption latency for CPU-bound tasks: |
bf0f6f24 | 44 | * |
21805085 | 45 | * NOTE: this latency value is not the same as the concept of |
d274a4ce IM |
46 | * 'timeslice length' - timeslices in CFS are of variable length |
47 | * and have no persistent notion like in traditional, time-slice | |
48 | * based scheduling concepts. | |
bf0f6f24 | 49 | * |
d274a4ce IM |
50 | * (to see the precise effective timeslice length of your workload, |
51 | * run vmstat and monitor the context-switches (cs) field) | |
2b4d5b25 IM |
52 | * |
53 | * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds) | |
bf0f6f24 | 54 | */ |
2b4d5b25 IM |
55 | unsigned int sysctl_sched_latency = 6000000ULL; |
56 | unsigned int normalized_sysctl_sched_latency = 6000000ULL; | |
2bd8e6d4 | 57 | |
1983a922 CE |
58 | /* |
59 | * The initial- and re-scaling of tunables is configurable | |
1983a922 CE |
60 | * |
61 | * Options are: | |
2b4d5b25 IM |
62 | * |
63 | * SCHED_TUNABLESCALING_NONE - unscaled, always *1 | |
64 | * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus) | |
65 | * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus | |
66 | * | |
67 | * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus)) | |
1983a922 | 68 | */ |
2b4d5b25 | 69 | enum sched_tunable_scaling sysctl_sched_tunable_scaling = SCHED_TUNABLESCALING_LOG; |
1983a922 | 70 | |
2bd8e6d4 | 71 | /* |
b2be5e96 | 72 | * Minimal preemption granularity for CPU-bound tasks: |
2b4d5b25 | 73 | * |
864616ee | 74 | * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds) |
2bd8e6d4 | 75 | */ |
2b4d5b25 IM |
76 | unsigned int sysctl_sched_min_granularity = 750000ULL; |
77 | unsigned int normalized_sysctl_sched_min_granularity = 750000ULL; | |
21805085 PZ |
78 | |
79 | /* | |
2b4d5b25 | 80 | * This value is kept at sysctl_sched_latency/sysctl_sched_min_granularity |
b2be5e96 | 81 | */ |
0bf377bb | 82 | static unsigned int sched_nr_latency = 8; |
b2be5e96 PZ |
83 | |
84 | /* | |
2bba22c5 | 85 | * After fork, child runs first. If set to 0 (default) then |
b2be5e96 | 86 | * parent will (try to) run first. |
21805085 | 87 | */ |
2bba22c5 | 88 | unsigned int sysctl_sched_child_runs_first __read_mostly; |
bf0f6f24 | 89 | |
bf0f6f24 IM |
90 | /* |
91 | * SCHED_OTHER wake-up granularity. | |
bf0f6f24 IM |
92 | * |
93 | * This option delays the preemption effects of decoupled workloads | |
94 | * and reduces their over-scheduling. Synchronous workloads will still | |
95 | * have immediate wakeup/sleep latencies. | |
2b4d5b25 IM |
96 | * |
97 | * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds) | |
bf0f6f24 | 98 | */ |
2b4d5b25 IM |
99 | unsigned int sysctl_sched_wakeup_granularity = 1000000UL; |
100 | unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL; | |
bf0f6f24 | 101 | |
2b4d5b25 | 102 | const_debug unsigned int sysctl_sched_migration_cost = 500000UL; |
da84d961 | 103 | |
afe06efd TC |
104 | #ifdef CONFIG_SMP |
105 | /* | |
106 | * For asym packing, by default the lower numbered cpu has higher priority. | |
107 | */ | |
108 | int __weak arch_asym_cpu_priority(int cpu) | |
109 | { | |
110 | return -cpu; | |
111 | } | |
112 | #endif | |
113 | ||
ec12cb7f PT |
114 | #ifdef CONFIG_CFS_BANDWIDTH |
115 | /* | |
116 | * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool | |
117 | * each time a cfs_rq requests quota. | |
118 | * | |
119 | * Note: in the case that the slice exceeds the runtime remaining (either due | |
120 | * to consumption or the quota being specified to be smaller than the slice) | |
121 | * we will always only issue the remaining available time. | |
122 | * | |
2b4d5b25 IM |
123 | * (default: 5 msec, units: microseconds) |
124 | */ | |
125 | unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL; | |
ec12cb7f PT |
126 | #endif |
127 | ||
3273163c MR |
128 | /* |
129 | * The margin used when comparing utilization with CPU capacity: | |
893c5d22 | 130 | * util * margin < capacity * 1024 |
2b4d5b25 IM |
131 | * |
132 | * (default: ~20%) | |
3273163c | 133 | */ |
2b4d5b25 | 134 | unsigned int capacity_margin = 1280; |
3273163c | 135 | |
8527632d PG |
136 | static inline void update_load_add(struct load_weight *lw, unsigned long inc) |
137 | { | |
138 | lw->weight += inc; | |
139 | lw->inv_weight = 0; | |
140 | } | |
141 | ||
142 | static inline void update_load_sub(struct load_weight *lw, unsigned long dec) | |
143 | { | |
144 | lw->weight -= dec; | |
145 | lw->inv_weight = 0; | |
146 | } | |
147 | ||
148 | static inline void update_load_set(struct load_weight *lw, unsigned long w) | |
149 | { | |
150 | lw->weight = w; | |
151 | lw->inv_weight = 0; | |
152 | } | |
153 | ||
029632fb PZ |
154 | /* |
155 | * Increase the granularity value when there are more CPUs, | |
156 | * because with more CPUs the 'effective latency' as visible | |
157 | * to users decreases. But the relationship is not linear, | |
158 | * so pick a second-best guess by going with the log2 of the | |
159 | * number of CPUs. | |
160 | * | |
161 | * This idea comes from the SD scheduler of Con Kolivas: | |
162 | */ | |
58ac93e4 | 163 | static unsigned int get_update_sysctl_factor(void) |
029632fb | 164 | { |
58ac93e4 | 165 | unsigned int cpus = min_t(unsigned int, num_online_cpus(), 8); |
029632fb PZ |
166 | unsigned int factor; |
167 | ||
168 | switch (sysctl_sched_tunable_scaling) { | |
169 | case SCHED_TUNABLESCALING_NONE: | |
170 | factor = 1; | |
171 | break; | |
172 | case SCHED_TUNABLESCALING_LINEAR: | |
173 | factor = cpus; | |
174 | break; | |
175 | case SCHED_TUNABLESCALING_LOG: | |
176 | default: | |
177 | factor = 1 + ilog2(cpus); | |
178 | break; | |
179 | } | |
180 | ||
181 | return factor; | |
182 | } | |
183 | ||
184 | static void update_sysctl(void) | |
185 | { | |
186 | unsigned int factor = get_update_sysctl_factor(); | |
187 | ||
188 | #define SET_SYSCTL(name) \ | |
189 | (sysctl_##name = (factor) * normalized_sysctl_##name) | |
190 | SET_SYSCTL(sched_min_granularity); | |
191 | SET_SYSCTL(sched_latency); | |
192 | SET_SYSCTL(sched_wakeup_granularity); | |
193 | #undef SET_SYSCTL | |
194 | } | |
195 | ||
196 | void sched_init_granularity(void) | |
197 | { | |
198 | update_sysctl(); | |
199 | } | |
200 | ||
9dbdb155 | 201 | #define WMULT_CONST (~0U) |
029632fb PZ |
202 | #define WMULT_SHIFT 32 |
203 | ||
9dbdb155 PZ |
204 | static void __update_inv_weight(struct load_weight *lw) |
205 | { | |
206 | unsigned long w; | |
207 | ||
208 | if (likely(lw->inv_weight)) | |
209 | return; | |
210 | ||
211 | w = scale_load_down(lw->weight); | |
212 | ||
213 | if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST)) | |
214 | lw->inv_weight = 1; | |
215 | else if (unlikely(!w)) | |
216 | lw->inv_weight = WMULT_CONST; | |
217 | else | |
218 | lw->inv_weight = WMULT_CONST / w; | |
219 | } | |
029632fb PZ |
220 | |
221 | /* | |
9dbdb155 PZ |
222 | * delta_exec * weight / lw.weight |
223 | * OR | |
224 | * (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT | |
225 | * | |
1c3de5e1 | 226 | * Either weight := NICE_0_LOAD and lw \e sched_prio_to_wmult[], in which case |
9dbdb155 PZ |
227 | * we're guaranteed shift stays positive because inv_weight is guaranteed to |
228 | * fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22. | |
229 | * | |
230 | * Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus | |
231 | * weight/lw.weight <= 1, and therefore our shift will also be positive. | |
029632fb | 232 | */ |
9dbdb155 | 233 | static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight *lw) |
029632fb | 234 | { |
9dbdb155 PZ |
235 | u64 fact = scale_load_down(weight); |
236 | int shift = WMULT_SHIFT; | |
029632fb | 237 | |
9dbdb155 | 238 | __update_inv_weight(lw); |
029632fb | 239 | |
9dbdb155 PZ |
240 | if (unlikely(fact >> 32)) { |
241 | while (fact >> 32) { | |
242 | fact >>= 1; | |
243 | shift--; | |
244 | } | |
029632fb PZ |
245 | } |
246 | ||
9dbdb155 PZ |
247 | /* hint to use a 32x32->64 mul */ |
248 | fact = (u64)(u32)fact * lw->inv_weight; | |
029632fb | 249 | |
9dbdb155 PZ |
250 | while (fact >> 32) { |
251 | fact >>= 1; | |
252 | shift--; | |
253 | } | |
029632fb | 254 | |
9dbdb155 | 255 | return mul_u64_u32_shr(delta_exec, fact, shift); |
029632fb PZ |
256 | } |
257 | ||
258 | ||
259 | const struct sched_class fair_sched_class; | |
a4c2f00f | 260 | |
bf0f6f24 IM |
261 | /************************************************************** |
262 | * CFS operations on generic schedulable entities: | |
263 | */ | |
264 | ||
62160e3f | 265 | #ifdef CONFIG_FAIR_GROUP_SCHED |
bf0f6f24 | 266 | |
62160e3f | 267 | /* cpu runqueue to which this cfs_rq is attached */ |
bf0f6f24 IM |
268 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
269 | { | |
62160e3f | 270 | return cfs_rq->rq; |
bf0f6f24 IM |
271 | } |
272 | ||
62160e3f IM |
273 | /* An entity is a task if it doesn't "own" a runqueue */ |
274 | #define entity_is_task(se) (!se->my_q) | |
bf0f6f24 | 275 | |
8f48894f PZ |
276 | static inline struct task_struct *task_of(struct sched_entity *se) |
277 | { | |
9148a3a1 | 278 | SCHED_WARN_ON(!entity_is_task(se)); |
8f48894f PZ |
279 | return container_of(se, struct task_struct, se); |
280 | } | |
281 | ||
b758149c PZ |
282 | /* Walk up scheduling entities hierarchy */ |
283 | #define for_each_sched_entity(se) \ | |
284 | for (; se; se = se->parent) | |
285 | ||
286 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) | |
287 | { | |
288 | return p->se.cfs_rq; | |
289 | } | |
290 | ||
291 | /* runqueue on which this entity is (to be) queued */ | |
292 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) | |
293 | { | |
294 | return se->cfs_rq; | |
295 | } | |
296 | ||
297 | /* runqueue "owned" by this group */ | |
298 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
299 | { | |
300 | return grp->my_q; | |
301 | } | |
302 | ||
3d4b47b4 PZ |
303 | static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
304 | { | |
a653325a PZ |
305 | struct rq *rq = rq_of(cfs_rq); |
306 | int cpu = cpu_of(rq); | |
307 | ||
308 | if (cfs_rq->on_list) | |
309 | return; | |
310 | ||
311 | cfs_rq->on_list = 1; | |
312 | ||
313 | /* | |
314 | * Ensure we either appear before our parent (if already | |
315 | * enqueued) or force our parent to appear after us when it is | |
316 | * enqueued. The fact that we always enqueue bottom-up | |
317 | * reduces this to two cases and a special case for the root | |
318 | * cfs_rq. Furthermore, it also means that we will always reset | |
319 | * tmp_alone_branch either when the branch is connected | |
320 | * to a tree or when we reach the top of the tree | |
321 | */ | |
322 | if (cfs_rq->tg->parent && | |
323 | cfs_rq->tg->parent->cfs_rq[cpu]->on_list) { | |
67e86250 | 324 | /* |
a653325a PZ |
325 | * If parent is already on the list, we add the child |
326 | * just before. Thanks to circular linked property of | |
327 | * the list, this means to put the child at the tail | |
328 | * of the list that starts by parent. | |
67e86250 | 329 | */ |
a653325a PZ |
330 | list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list, |
331 | &(cfs_rq->tg->parent->cfs_rq[cpu]->leaf_cfs_rq_list)); | |
332 | /* | |
333 | * The branch is now connected to its tree so we can | |
334 | * reset tmp_alone_branch to the beginning of the | |
335 | * list. | |
336 | */ | |
337 | rq->tmp_alone_branch = &rq->leaf_cfs_rq_list; | |
338 | return; | |
339 | } | |
3d4b47b4 | 340 | |
a653325a PZ |
341 | if (!cfs_rq->tg->parent) { |
342 | /* | |
343 | * cfs rq without parent should be put | |
344 | * at the tail of the list. | |
345 | */ | |
346 | list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list, | |
347 | &rq->leaf_cfs_rq_list); | |
348 | /* | |
349 | * We have reach the top of a tree so we can reset | |
350 | * tmp_alone_branch to the beginning of the list. | |
351 | */ | |
352 | rq->tmp_alone_branch = &rq->leaf_cfs_rq_list; | |
353 | return; | |
3d4b47b4 | 354 | } |
a653325a PZ |
355 | |
356 | /* | |
357 | * The parent has not already been added so we want to | |
358 | * make sure that it will be put after us. | |
359 | * tmp_alone_branch points to the begin of the branch | |
360 | * where we will add parent. | |
361 | */ | |
362 | list_add_rcu(&cfs_rq->leaf_cfs_rq_list, rq->tmp_alone_branch); | |
363 | /* | |
364 | * update tmp_alone_branch to points to the new begin | |
365 | * of the branch | |
366 | */ | |
367 | rq->tmp_alone_branch = &cfs_rq->leaf_cfs_rq_list; | |
3d4b47b4 PZ |
368 | } |
369 | ||
370 | static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) | |
371 | { | |
372 | if (cfs_rq->on_list) { | |
373 | list_del_rcu(&cfs_rq->leaf_cfs_rq_list); | |
374 | cfs_rq->on_list = 0; | |
375 | } | |
376 | } | |
377 | ||
a653325a PZ |
378 | static inline void assert_list_leaf_cfs_rq(struct rq *rq) |
379 | { | |
380 | SCHED_WARN_ON(rq->tmp_alone_branch != &rq->leaf_cfs_rq_list); | |
381 | } | |
382 | ||
383 | /* Iterate through all cfs_rq's on a runqueue in bottom-up order */ | |
cf740dd8 LT |
384 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
385 | list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) | |
b758149c PZ |
386 | |
387 | /* Do the two (enqueued) entities belong to the same group ? */ | |
fed14d45 | 388 | static inline struct cfs_rq * |
b758149c PZ |
389 | is_same_group(struct sched_entity *se, struct sched_entity *pse) |
390 | { | |
391 | if (se->cfs_rq == pse->cfs_rq) | |
fed14d45 | 392 | return se->cfs_rq; |
b758149c | 393 | |
fed14d45 | 394 | return NULL; |
b758149c PZ |
395 | } |
396 | ||
397 | static inline struct sched_entity *parent_entity(struct sched_entity *se) | |
398 | { | |
399 | return se->parent; | |
400 | } | |
401 | ||
464b7527 PZ |
402 | static void |
403 | find_matching_se(struct sched_entity **se, struct sched_entity **pse) | |
404 | { | |
405 | int se_depth, pse_depth; | |
406 | ||
407 | /* | |
408 | * preemption test can be made between sibling entities who are in the | |
409 | * same cfs_rq i.e who have a common parent. Walk up the hierarchy of | |
410 | * both tasks until we find their ancestors who are siblings of common | |
411 | * parent. | |
412 | */ | |
413 | ||
414 | /* First walk up until both entities are at same depth */ | |
fed14d45 PZ |
415 | se_depth = (*se)->depth; |
416 | pse_depth = (*pse)->depth; | |
464b7527 PZ |
417 | |
418 | while (se_depth > pse_depth) { | |
419 | se_depth--; | |
420 | *se = parent_entity(*se); | |
421 | } | |
422 | ||
423 | while (pse_depth > se_depth) { | |
424 | pse_depth--; | |
425 | *pse = parent_entity(*pse); | |
426 | } | |
427 | ||
428 | while (!is_same_group(*se, *pse)) { | |
429 | *se = parent_entity(*se); | |
430 | *pse = parent_entity(*pse); | |
431 | } | |
432 | } | |
433 | ||
8f48894f PZ |
434 | #else /* !CONFIG_FAIR_GROUP_SCHED */ |
435 | ||
436 | static inline struct task_struct *task_of(struct sched_entity *se) | |
437 | { | |
438 | return container_of(se, struct task_struct, se); | |
439 | } | |
bf0f6f24 | 440 | |
62160e3f IM |
441 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
442 | { | |
443 | return container_of(cfs_rq, struct rq, cfs); | |
bf0f6f24 IM |
444 | } |
445 | ||
446 | #define entity_is_task(se) 1 | |
447 | ||
b758149c PZ |
448 | #define for_each_sched_entity(se) \ |
449 | for (; se; se = NULL) | |
bf0f6f24 | 450 | |
b758149c | 451 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) |
bf0f6f24 | 452 | { |
b758149c | 453 | return &task_rq(p)->cfs; |
bf0f6f24 IM |
454 | } |
455 | ||
b758149c PZ |
456 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) |
457 | { | |
458 | struct task_struct *p = task_of(se); | |
459 | struct rq *rq = task_rq(p); | |
460 | ||
461 | return &rq->cfs; | |
462 | } | |
463 | ||
464 | /* runqueue "owned" by this group */ | |
465 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
466 | { | |
467 | return NULL; | |
468 | } | |
469 | ||
3d4b47b4 PZ |
470 | static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
471 | { | |
472 | } | |
473 | ||
474 | static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) | |
475 | { | |
476 | } | |
477 | ||
a653325a PZ |
478 | static inline void assert_list_leaf_cfs_rq(struct rq *rq) |
479 | { | |
480 | } | |
481 | ||
cf740dd8 LT |
482 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
483 | for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) | |
b758149c | 484 | |
b758149c PZ |
485 | static inline struct sched_entity *parent_entity(struct sched_entity *se) |
486 | { | |
487 | return NULL; | |
488 | } | |
489 | ||
464b7527 PZ |
490 | static inline void |
491 | find_matching_se(struct sched_entity **se, struct sched_entity **pse) | |
492 | { | |
493 | } | |
494 | ||
b758149c PZ |
495 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
496 | ||
6c16a6dc | 497 | static __always_inline |
9dbdb155 | 498 | void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec); |
bf0f6f24 IM |
499 | |
500 | /************************************************************** | |
501 | * Scheduling class tree data structure manipulation methods: | |
502 | */ | |
503 | ||
1bf08230 | 504 | static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime) |
02e0431a | 505 | { |
1bf08230 | 506 | s64 delta = (s64)(vruntime - max_vruntime); |
368059a9 | 507 | if (delta > 0) |
1bf08230 | 508 | max_vruntime = vruntime; |
02e0431a | 509 | |
1bf08230 | 510 | return max_vruntime; |
02e0431a PZ |
511 | } |
512 | ||
0702e3eb | 513 | static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime) |
b0ffd246 PZ |
514 | { |
515 | s64 delta = (s64)(vruntime - min_vruntime); | |
516 | if (delta < 0) | |
517 | min_vruntime = vruntime; | |
518 | ||
519 | return min_vruntime; | |
520 | } | |
521 | ||
54fdc581 FC |
522 | static inline int entity_before(struct sched_entity *a, |
523 | struct sched_entity *b) | |
524 | { | |
525 | return (s64)(a->vruntime - b->vruntime) < 0; | |
526 | } | |
527 | ||
1af5f730 PZ |
528 | static void update_min_vruntime(struct cfs_rq *cfs_rq) |
529 | { | |
b60205c7 | 530 | struct sched_entity *curr = cfs_rq->curr; |
bfb06889 | 531 | struct rb_node *leftmost = rb_first_cached(&cfs_rq->tasks_timeline); |
b60205c7 | 532 | |
1af5f730 PZ |
533 | u64 vruntime = cfs_rq->min_vruntime; |
534 | ||
b60205c7 PZ |
535 | if (curr) { |
536 | if (curr->on_rq) | |
537 | vruntime = curr->vruntime; | |
538 | else | |
539 | curr = NULL; | |
540 | } | |
1af5f730 | 541 | |
bfb06889 DB |
542 | if (leftmost) { /* non-empty tree */ |
543 | struct sched_entity *se; | |
544 | se = rb_entry(leftmost, struct sched_entity, run_node); | |
1af5f730 | 545 | |
b60205c7 | 546 | if (!curr) |
1af5f730 PZ |
547 | vruntime = se->vruntime; |
548 | else | |
549 | vruntime = min_vruntime(vruntime, se->vruntime); | |
550 | } | |
551 | ||
1bf08230 | 552 | /* ensure we never gain time by being placed backwards. */ |
1af5f730 | 553 | cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); |
3fe1698b PZ |
554 | #ifndef CONFIG_64BIT |
555 | smp_wmb(); | |
556 | cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; | |
557 | #endif | |
1af5f730 PZ |
558 | } |
559 | ||
bf0f6f24 IM |
560 | /* |
561 | * Enqueue an entity into the rb-tree: | |
562 | */ | |
0702e3eb | 563 | static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 564 | { |
bfb06889 | 565 | struct rb_node **link = &cfs_rq->tasks_timeline.rb_root.rb_node; |
bf0f6f24 IM |
566 | struct rb_node *parent = NULL; |
567 | struct sched_entity *entry; | |
bfb06889 | 568 | bool leftmost = true; |
bf0f6f24 IM |
569 | |
570 | /* | |
571 | * Find the right place in the rbtree: | |
572 | */ | |
573 | while (*link) { | |
574 | parent = *link; | |
575 | entry = rb_entry(parent, struct sched_entity, run_node); | |
576 | /* | |
577 | * We dont care about collisions. Nodes with | |
578 | * the same key stay together. | |
579 | */ | |
2bd2d6f2 | 580 | if (entity_before(se, entry)) { |
bf0f6f24 IM |
581 | link = &parent->rb_left; |
582 | } else { | |
583 | link = &parent->rb_right; | |
bfb06889 | 584 | leftmost = false; |
bf0f6f24 IM |
585 | } |
586 | } | |
587 | ||
bf0f6f24 | 588 | rb_link_node(&se->run_node, parent, link); |
bfb06889 DB |
589 | rb_insert_color_cached(&se->run_node, |
590 | &cfs_rq->tasks_timeline, leftmost); | |
bf0f6f24 IM |
591 | } |
592 | ||
0702e3eb | 593 | static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 594 | { |
bfb06889 | 595 | rb_erase_cached(&se->run_node, &cfs_rq->tasks_timeline); |
bf0f6f24 IM |
596 | } |
597 | ||
029632fb | 598 | struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq) |
bf0f6f24 | 599 | { |
bfb06889 | 600 | struct rb_node *left = rb_first_cached(&cfs_rq->tasks_timeline); |
f4b6755f PZ |
601 | |
602 | if (!left) | |
603 | return NULL; | |
604 | ||
605 | return rb_entry(left, struct sched_entity, run_node); | |
bf0f6f24 IM |
606 | } |
607 | ||
ac53db59 RR |
608 | static struct sched_entity *__pick_next_entity(struct sched_entity *se) |
609 | { | |
610 | struct rb_node *next = rb_next(&se->run_node); | |
611 | ||
612 | if (!next) | |
613 | return NULL; | |
614 | ||
615 | return rb_entry(next, struct sched_entity, run_node); | |
616 | } | |
617 | ||
618 | #ifdef CONFIG_SCHED_DEBUG | |
029632fb | 619 | struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) |
aeb73b04 | 620 | { |
bfb06889 | 621 | struct rb_node *last = rb_last(&cfs_rq->tasks_timeline.rb_root); |
aeb73b04 | 622 | |
70eee74b BS |
623 | if (!last) |
624 | return NULL; | |
7eee3e67 IM |
625 | |
626 | return rb_entry(last, struct sched_entity, run_node); | |
aeb73b04 PZ |
627 | } |
628 | ||
bf0f6f24 IM |
629 | /************************************************************** |
630 | * Scheduling class statistics methods: | |
631 | */ | |
632 | ||
acb4a848 | 633 | int sched_proc_update_handler(struct ctl_table *table, int write, |
8d65af78 | 634 | void __user *buffer, size_t *lenp, |
b2be5e96 PZ |
635 | loff_t *ppos) |
636 | { | |
8d65af78 | 637 | int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
58ac93e4 | 638 | unsigned int factor = get_update_sysctl_factor(); |
b2be5e96 PZ |
639 | |
640 | if (ret || !write) | |
641 | return ret; | |
642 | ||
643 | sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency, | |
644 | sysctl_sched_min_granularity); | |
645 | ||
acb4a848 CE |
646 | #define WRT_SYSCTL(name) \ |
647 | (normalized_sysctl_##name = sysctl_##name / (factor)) | |
648 | WRT_SYSCTL(sched_min_granularity); | |
649 | WRT_SYSCTL(sched_latency); | |
650 | WRT_SYSCTL(sched_wakeup_granularity); | |
acb4a848 CE |
651 | #undef WRT_SYSCTL |
652 | ||
b2be5e96 PZ |
653 | return 0; |
654 | } | |
655 | #endif | |
647e7cac | 656 | |
a7be37ac | 657 | /* |
f9c0b095 | 658 | * delta /= w |
a7be37ac | 659 | */ |
9dbdb155 | 660 | static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se) |
a7be37ac | 661 | { |
f9c0b095 | 662 | if (unlikely(se->load.weight != NICE_0_LOAD)) |
9dbdb155 | 663 | delta = __calc_delta(delta, NICE_0_LOAD, &se->load); |
a7be37ac PZ |
664 | |
665 | return delta; | |
666 | } | |
667 | ||
647e7cac IM |
668 | /* |
669 | * The idea is to set a period in which each task runs once. | |
670 | * | |
532b1858 | 671 | * When there are too many tasks (sched_nr_latency) we have to stretch |
647e7cac IM |
672 | * this period because otherwise the slices get too small. |
673 | * | |
674 | * p = (nr <= nl) ? l : l*nr/nl | |
675 | */ | |
4d78e7b6 PZ |
676 | static u64 __sched_period(unsigned long nr_running) |
677 | { | |
8e2b0bf3 BF |
678 | if (unlikely(nr_running > sched_nr_latency)) |
679 | return nr_running * sysctl_sched_min_granularity; | |
680 | else | |
681 | return sysctl_sched_latency; | |
4d78e7b6 PZ |
682 | } |
683 | ||
647e7cac IM |
684 | /* |
685 | * We calculate the wall-time slice from the period by taking a part | |
686 | * proportional to the weight. | |
687 | * | |
f9c0b095 | 688 | * s = p*P[w/rw] |
647e7cac | 689 | */ |
6d0f0ebd | 690 | static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
21805085 | 691 | { |
0a582440 | 692 | u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq); |
f9c0b095 | 693 | |
0a582440 | 694 | for_each_sched_entity(se) { |
6272d68c | 695 | struct load_weight *load; |
3104bf03 | 696 | struct load_weight lw; |
6272d68c LM |
697 | |
698 | cfs_rq = cfs_rq_of(se); | |
699 | load = &cfs_rq->load; | |
f9c0b095 | 700 | |
0a582440 | 701 | if (unlikely(!se->on_rq)) { |
3104bf03 | 702 | lw = cfs_rq->load; |
0a582440 MG |
703 | |
704 | update_load_add(&lw, se->load.weight); | |
705 | load = &lw; | |
706 | } | |
9dbdb155 | 707 | slice = __calc_delta(slice, se->load.weight, load); |
0a582440 MG |
708 | } |
709 | return slice; | |
bf0f6f24 IM |
710 | } |
711 | ||
647e7cac | 712 | /* |
660cc00f | 713 | * We calculate the vruntime slice of a to-be-inserted task. |
647e7cac | 714 | * |
f9c0b095 | 715 | * vs = s/w |
647e7cac | 716 | */ |
f9c0b095 | 717 | static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
67e9fb2a | 718 | { |
f9c0b095 | 719 | return calc_delta_fair(sched_slice(cfs_rq, se), se); |
a7be37ac PZ |
720 | } |
721 | ||
a75cdaa9 | 722 | #ifdef CONFIG_SMP |
283e2ed3 PZ |
723 | |
724 | #include "sched-pelt.h" | |
725 | ||
772bd008 | 726 | static int select_idle_sibling(struct task_struct *p, int prev_cpu, int cpu); |
fb13c7ee MG |
727 | static unsigned long task_h_load(struct task_struct *p); |
728 | ||
540247fb YD |
729 | /* Give new sched_entity start runnable values to heavy its load in infant time */ |
730 | void init_entity_runnable_average(struct sched_entity *se) | |
a75cdaa9 | 731 | { |
540247fb | 732 | struct sched_avg *sa = &se->avg; |
a75cdaa9 | 733 | |
f207934f PZ |
734 | memset(sa, 0, sizeof(*sa)); |
735 | ||
b5a9b340 VG |
736 | /* |
737 | * Tasks are intialized with full load to be seen as heavy tasks until | |
738 | * they get a chance to stabilize to their real load level. | |
739 | * Group entities are intialized with zero load to reflect the fact that | |
740 | * nothing has been attached to the task group yet. | |
741 | */ | |
742 | if (entity_is_task(se)) | |
1ea6c46a | 743 | sa->runnable_load_avg = sa->load_avg = scale_load_down(se->load.weight); |
1ea6c46a | 744 | |
f207934f PZ |
745 | se->runnable_weight = se->load.weight; |
746 | ||
9d89c257 | 747 | /* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */ |
a75cdaa9 | 748 | } |
7ea241af | 749 | |
7dc603c9 | 750 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq); |
df217913 | 751 | static void attach_entity_cfs_rq(struct sched_entity *se); |
7dc603c9 | 752 | |
2b8c41da YD |
753 | /* |
754 | * With new tasks being created, their initial util_avgs are extrapolated | |
755 | * based on the cfs_rq's current util_avg: | |
756 | * | |
757 | * util_avg = cfs_rq->util_avg / (cfs_rq->load_avg + 1) * se.load.weight | |
758 | * | |
759 | * However, in many cases, the above util_avg does not give a desired | |
760 | * value. Moreover, the sum of the util_avgs may be divergent, such | |
761 | * as when the series is a harmonic series. | |
762 | * | |
763 | * To solve this problem, we also cap the util_avg of successive tasks to | |
764 | * only 1/2 of the left utilization budget: | |
765 | * | |
32ac9150 | 766 | * util_avg_cap = (cpu_scale - cfs_rq->avg.util_avg) / 2^n |
2b8c41da | 767 | * |
32ac9150 | 768 | * where n denotes the nth task and cpu_scale the CPU capacity. |
2b8c41da | 769 | * |
32ac9150 QP |
770 | * For example, for a CPU with 1024 of capacity, a simplest series from |
771 | * the beginning would be like: | |
2b8c41da YD |
772 | * |
773 | * task util_avg: 512, 256, 128, 64, 32, 16, 8, ... | |
774 | * cfs_rq util_avg: 512, 768, 896, 960, 992, 1008, 1016, ... | |
775 | * | |
776 | * Finally, that extrapolated util_avg is clamped to the cap (util_avg_cap) | |
777 | * if util_avg > util_avg_cap. | |
778 | */ | |
779 | void post_init_entity_util_avg(struct sched_entity *se) | |
780 | { | |
781 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
782 | struct sched_avg *sa = &se->avg; | |
32ac9150 QP |
783 | long cpu_scale = arch_scale_cpu_capacity(NULL, cpu_of(rq_of(cfs_rq))); |
784 | long cap = (long)(cpu_scale - cfs_rq->avg.util_avg) / 2; | |
2b8c41da YD |
785 | |
786 | if (cap > 0) { | |
787 | if (cfs_rq->avg.util_avg != 0) { | |
788 | sa->util_avg = cfs_rq->avg.util_avg * se->load.weight; | |
789 | sa->util_avg /= (cfs_rq->avg.load_avg + 1); | |
790 | ||
791 | if (sa->util_avg > cap) | |
792 | sa->util_avg = cap; | |
793 | } else { | |
794 | sa->util_avg = cap; | |
795 | } | |
2b8c41da | 796 | } |
7dc603c9 PZ |
797 | |
798 | if (entity_is_task(se)) { | |
799 | struct task_struct *p = task_of(se); | |
800 | if (p->sched_class != &fair_sched_class) { | |
801 | /* | |
802 | * For !fair tasks do: | |
803 | * | |
3a123bbb | 804 | update_cfs_rq_load_avg(now, cfs_rq); |
7dc603c9 PZ |
805 | attach_entity_load_avg(cfs_rq, se); |
806 | switched_from_fair(rq, p); | |
807 | * | |
808 | * such that the next switched_to_fair() has the | |
809 | * expected state. | |
810 | */ | |
df217913 | 811 | se->avg.last_update_time = cfs_rq_clock_task(cfs_rq); |
7dc603c9 PZ |
812 | return; |
813 | } | |
814 | } | |
815 | ||
df217913 | 816 | attach_entity_cfs_rq(se); |
2b8c41da YD |
817 | } |
818 | ||
7dc603c9 | 819 | #else /* !CONFIG_SMP */ |
540247fb | 820 | void init_entity_runnable_average(struct sched_entity *se) |
a75cdaa9 AS |
821 | { |
822 | } | |
2b8c41da YD |
823 | void post_init_entity_util_avg(struct sched_entity *se) |
824 | { | |
825 | } | |
3d30544f PZ |
826 | static void update_tg_load_avg(struct cfs_rq *cfs_rq, int force) |
827 | { | |
828 | } | |
7dc603c9 | 829 | #endif /* CONFIG_SMP */ |
a75cdaa9 | 830 | |
bf0f6f24 | 831 | /* |
9dbdb155 | 832 | * Update the current task's runtime statistics. |
bf0f6f24 | 833 | */ |
b7cc0896 | 834 | static void update_curr(struct cfs_rq *cfs_rq) |
bf0f6f24 | 835 | { |
429d43bc | 836 | struct sched_entity *curr = cfs_rq->curr; |
78becc27 | 837 | u64 now = rq_clock_task(rq_of(cfs_rq)); |
9dbdb155 | 838 | u64 delta_exec; |
bf0f6f24 IM |
839 | |
840 | if (unlikely(!curr)) | |
841 | return; | |
842 | ||
9dbdb155 PZ |
843 | delta_exec = now - curr->exec_start; |
844 | if (unlikely((s64)delta_exec <= 0)) | |
34f28ecd | 845 | return; |
bf0f6f24 | 846 | |
8ebc91d9 | 847 | curr->exec_start = now; |
d842de87 | 848 | |
9dbdb155 PZ |
849 | schedstat_set(curr->statistics.exec_max, |
850 | max(delta_exec, curr->statistics.exec_max)); | |
851 | ||
852 | curr->sum_exec_runtime += delta_exec; | |
ae92882e | 853 | schedstat_add(cfs_rq->exec_clock, delta_exec); |
9dbdb155 PZ |
854 | |
855 | curr->vruntime += calc_delta_fair(delta_exec, curr); | |
856 | update_min_vruntime(cfs_rq); | |
857 | ||
d842de87 SV |
858 | if (entity_is_task(curr)) { |
859 | struct task_struct *curtask = task_of(curr); | |
860 | ||
f977bb49 | 861 | trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); |
d2cc5ed6 | 862 | cgroup_account_cputime(curtask, delta_exec); |
f06febc9 | 863 | account_group_exec_runtime(curtask, delta_exec); |
d842de87 | 864 | } |
ec12cb7f PT |
865 | |
866 | account_cfs_rq_runtime(cfs_rq, delta_exec); | |
bf0f6f24 IM |
867 | } |
868 | ||
6e998916 SG |
869 | static void update_curr_fair(struct rq *rq) |
870 | { | |
871 | update_curr(cfs_rq_of(&rq->curr->se)); | |
872 | } | |
873 | ||
bf0f6f24 | 874 | static inline void |
5870db5b | 875 | update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 876 | { |
4fa8d299 JP |
877 | u64 wait_start, prev_wait_start; |
878 | ||
879 | if (!schedstat_enabled()) | |
880 | return; | |
881 | ||
882 | wait_start = rq_clock(rq_of(cfs_rq)); | |
883 | prev_wait_start = schedstat_val(se->statistics.wait_start); | |
3ea94de1 JP |
884 | |
885 | if (entity_is_task(se) && task_on_rq_migrating(task_of(se)) && | |
4fa8d299 JP |
886 | likely(wait_start > prev_wait_start)) |
887 | wait_start -= prev_wait_start; | |
3ea94de1 | 888 | |
4fa8d299 | 889 | schedstat_set(se->statistics.wait_start, wait_start); |
bf0f6f24 IM |
890 | } |
891 | ||
4fa8d299 | 892 | static inline void |
3ea94de1 JP |
893 | update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) |
894 | { | |
895 | struct task_struct *p; | |
cb251765 MG |
896 | u64 delta; |
897 | ||
4fa8d299 JP |
898 | if (!schedstat_enabled()) |
899 | return; | |
900 | ||
901 | delta = rq_clock(rq_of(cfs_rq)) - schedstat_val(se->statistics.wait_start); | |
3ea94de1 JP |
902 | |
903 | if (entity_is_task(se)) { | |
904 | p = task_of(se); | |
905 | if (task_on_rq_migrating(p)) { | |
906 | /* | |
907 | * Preserve migrating task's wait time so wait_start | |
908 | * time stamp can be adjusted to accumulate wait time | |
909 | * prior to migration. | |
910 | */ | |
4fa8d299 | 911 | schedstat_set(se->statistics.wait_start, delta); |
3ea94de1 JP |
912 | return; |
913 | } | |
914 | trace_sched_stat_wait(p, delta); | |
915 | } | |
916 | ||
4fa8d299 JP |
917 | schedstat_set(se->statistics.wait_max, |
918 | max(schedstat_val(se->statistics.wait_max), delta)); | |
919 | schedstat_inc(se->statistics.wait_count); | |
920 | schedstat_add(se->statistics.wait_sum, delta); | |
921 | schedstat_set(se->statistics.wait_start, 0); | |
3ea94de1 | 922 | } |
3ea94de1 | 923 | |
4fa8d299 | 924 | static inline void |
1a3d027c JP |
925 | update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) |
926 | { | |
927 | struct task_struct *tsk = NULL; | |
4fa8d299 JP |
928 | u64 sleep_start, block_start; |
929 | ||
930 | if (!schedstat_enabled()) | |
931 | return; | |
932 | ||
933 | sleep_start = schedstat_val(se->statistics.sleep_start); | |
934 | block_start = schedstat_val(se->statistics.block_start); | |
1a3d027c JP |
935 | |
936 | if (entity_is_task(se)) | |
937 | tsk = task_of(se); | |
938 | ||
4fa8d299 JP |
939 | if (sleep_start) { |
940 | u64 delta = rq_clock(rq_of(cfs_rq)) - sleep_start; | |
1a3d027c JP |
941 | |
942 | if ((s64)delta < 0) | |
943 | delta = 0; | |
944 | ||
4fa8d299 JP |
945 | if (unlikely(delta > schedstat_val(se->statistics.sleep_max))) |
946 | schedstat_set(se->statistics.sleep_max, delta); | |
1a3d027c | 947 | |
4fa8d299 JP |
948 | schedstat_set(se->statistics.sleep_start, 0); |
949 | schedstat_add(se->statistics.sum_sleep_runtime, delta); | |
1a3d027c JP |
950 | |
951 | if (tsk) { | |
952 | account_scheduler_latency(tsk, delta >> 10, 1); | |
953 | trace_sched_stat_sleep(tsk, delta); | |
954 | } | |
955 | } | |
4fa8d299 JP |
956 | if (block_start) { |
957 | u64 delta = rq_clock(rq_of(cfs_rq)) - block_start; | |
1a3d027c JP |
958 | |
959 | if ((s64)delta < 0) | |
960 | delta = 0; | |
961 | ||
4fa8d299 JP |
962 | if (unlikely(delta > schedstat_val(se->statistics.block_max))) |
963 | schedstat_set(se->statistics.block_max, delta); | |
1a3d027c | 964 | |
4fa8d299 JP |
965 | schedstat_set(se->statistics.block_start, 0); |
966 | schedstat_add(se->statistics.sum_sleep_runtime, delta); | |
1a3d027c JP |
967 | |
968 | if (tsk) { | |
969 | if (tsk->in_iowait) { | |
4fa8d299 JP |
970 | schedstat_add(se->statistics.iowait_sum, delta); |
971 | schedstat_inc(se->statistics.iowait_count); | |
1a3d027c JP |
972 | trace_sched_stat_iowait(tsk, delta); |
973 | } | |
974 | ||
975 | trace_sched_stat_blocked(tsk, delta); | |
976 | ||
977 | /* | |
978 | * Blocking time is in units of nanosecs, so shift by | |
979 | * 20 to get a milliseconds-range estimation of the | |
980 | * amount of time that the task spent sleeping: | |
981 | */ | |
982 | if (unlikely(prof_on == SLEEP_PROFILING)) { | |
983 | profile_hits(SLEEP_PROFILING, | |
984 | (void *)get_wchan(tsk), | |
985 | delta >> 20); | |
986 | } | |
987 | account_scheduler_latency(tsk, delta >> 10, 0); | |
988 | } | |
989 | } | |
3ea94de1 | 990 | } |
3ea94de1 | 991 | |
bf0f6f24 IM |
992 | /* |
993 | * Task is being enqueued - update stats: | |
994 | */ | |
cb251765 | 995 | static inline void |
1a3d027c | 996 | update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 997 | { |
4fa8d299 JP |
998 | if (!schedstat_enabled()) |
999 | return; | |
1000 | ||
bf0f6f24 IM |
1001 | /* |
1002 | * Are we enqueueing a waiting task? (for current tasks | |
1003 | * a dequeue/enqueue event is a NOP) | |
1004 | */ | |
429d43bc | 1005 | if (se != cfs_rq->curr) |
5870db5b | 1006 | update_stats_wait_start(cfs_rq, se); |
1a3d027c JP |
1007 | |
1008 | if (flags & ENQUEUE_WAKEUP) | |
1009 | update_stats_enqueue_sleeper(cfs_rq, se); | |
bf0f6f24 IM |
1010 | } |
1011 | ||
bf0f6f24 | 1012 | static inline void |
cb251765 | 1013 | update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 1014 | { |
4fa8d299 JP |
1015 | |
1016 | if (!schedstat_enabled()) | |
1017 | return; | |
1018 | ||
bf0f6f24 IM |
1019 | /* |
1020 | * Mark the end of the wait period if dequeueing a | |
1021 | * waiting task: | |
1022 | */ | |
429d43bc | 1023 | if (se != cfs_rq->curr) |
9ef0a961 | 1024 | update_stats_wait_end(cfs_rq, se); |
cb251765 | 1025 | |
4fa8d299 JP |
1026 | if ((flags & DEQUEUE_SLEEP) && entity_is_task(se)) { |
1027 | struct task_struct *tsk = task_of(se); | |
cb251765 | 1028 | |
4fa8d299 JP |
1029 | if (tsk->state & TASK_INTERRUPTIBLE) |
1030 | schedstat_set(se->statistics.sleep_start, | |
1031 | rq_clock(rq_of(cfs_rq))); | |
1032 | if (tsk->state & TASK_UNINTERRUPTIBLE) | |
1033 | schedstat_set(se->statistics.block_start, | |
1034 | rq_clock(rq_of(cfs_rq))); | |
cb251765 | 1035 | } |
cb251765 MG |
1036 | } |
1037 | ||
bf0f6f24 IM |
1038 | /* |
1039 | * We are picking a new current task - update its stats: | |
1040 | */ | |
1041 | static inline void | |
79303e9e | 1042 | update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 IM |
1043 | { |
1044 | /* | |
1045 | * We are starting a new run period: | |
1046 | */ | |
78becc27 | 1047 | se->exec_start = rq_clock_task(rq_of(cfs_rq)); |
bf0f6f24 IM |
1048 | } |
1049 | ||
bf0f6f24 IM |
1050 | /************************************************** |
1051 | * Scheduling class queueing methods: | |
1052 | */ | |
1053 | ||
cbee9f88 PZ |
1054 | #ifdef CONFIG_NUMA_BALANCING |
1055 | /* | |
598f0ec0 MG |
1056 | * Approximate time to scan a full NUMA task in ms. The task scan period is |
1057 | * calculated based on the tasks virtual memory size and | |
1058 | * numa_balancing_scan_size. | |
cbee9f88 | 1059 | */ |
598f0ec0 MG |
1060 | unsigned int sysctl_numa_balancing_scan_period_min = 1000; |
1061 | unsigned int sysctl_numa_balancing_scan_period_max = 60000; | |
6e5fb223 PZ |
1062 | |
1063 | /* Portion of address space to scan in MB */ | |
1064 | unsigned int sysctl_numa_balancing_scan_size = 256; | |
cbee9f88 | 1065 | |
4b96a29b PZ |
1066 | /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */ |
1067 | unsigned int sysctl_numa_balancing_scan_delay = 1000; | |
1068 | ||
b5dd77c8 RR |
1069 | struct numa_group { |
1070 | atomic_t refcount; | |
1071 | ||
1072 | spinlock_t lock; /* nr_tasks, tasks */ | |
1073 | int nr_tasks; | |
1074 | pid_t gid; | |
1075 | int active_nodes; | |
1076 | ||
1077 | struct rcu_head rcu; | |
1078 | unsigned long total_faults; | |
1079 | unsigned long max_faults_cpu; | |
1080 | /* | |
1081 | * Faults_cpu is used to decide whether memory should move | |
1082 | * towards the CPU. As a consequence, these stats are weighted | |
1083 | * more by CPU use than by memory faults. | |
1084 | */ | |
1085 | unsigned long *faults_cpu; | |
1086 | unsigned long faults[0]; | |
1087 | }; | |
1088 | ||
1089 | static inline unsigned long group_faults_priv(struct numa_group *ng); | |
1090 | static inline unsigned long group_faults_shared(struct numa_group *ng); | |
1091 | ||
598f0ec0 MG |
1092 | static unsigned int task_nr_scan_windows(struct task_struct *p) |
1093 | { | |
1094 | unsigned long rss = 0; | |
1095 | unsigned long nr_scan_pages; | |
1096 | ||
1097 | /* | |
1098 | * Calculations based on RSS as non-present and empty pages are skipped | |
1099 | * by the PTE scanner and NUMA hinting faults should be trapped based | |
1100 | * on resident pages | |
1101 | */ | |
1102 | nr_scan_pages = sysctl_numa_balancing_scan_size << (20 - PAGE_SHIFT); | |
1103 | rss = get_mm_rss(p->mm); | |
1104 | if (!rss) | |
1105 | rss = nr_scan_pages; | |
1106 | ||
1107 | rss = round_up(rss, nr_scan_pages); | |
1108 | return rss / nr_scan_pages; | |
1109 | } | |
1110 | ||
1111 | /* For sanitys sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */ | |
1112 | #define MAX_SCAN_WINDOW 2560 | |
1113 | ||
1114 | static unsigned int task_scan_min(struct task_struct *p) | |
1115 | { | |
316c1608 | 1116 | unsigned int scan_size = READ_ONCE(sysctl_numa_balancing_scan_size); |
598f0ec0 MG |
1117 | unsigned int scan, floor; |
1118 | unsigned int windows = 1; | |
1119 | ||
64192658 KT |
1120 | if (scan_size < MAX_SCAN_WINDOW) |
1121 | windows = MAX_SCAN_WINDOW / scan_size; | |
598f0ec0 MG |
1122 | floor = 1000 / windows; |
1123 | ||
1124 | scan = sysctl_numa_balancing_scan_period_min / task_nr_scan_windows(p); | |
1125 | return max_t(unsigned int, floor, scan); | |
1126 | } | |
1127 | ||
b5dd77c8 RR |
1128 | static unsigned int task_scan_start(struct task_struct *p) |
1129 | { | |
1130 | unsigned long smin = task_scan_min(p); | |
1131 | unsigned long period = smin; | |
1132 | ||
1133 | /* Scale the maximum scan period with the amount of shared memory. */ | |
1134 | if (p->numa_group) { | |
1135 | struct numa_group *ng = p->numa_group; | |
1136 | unsigned long shared = group_faults_shared(ng); | |
1137 | unsigned long private = group_faults_priv(ng); | |
1138 | ||
1139 | period *= atomic_read(&ng->refcount); | |
1140 | period *= shared + 1; | |
1141 | period /= private + shared + 1; | |
1142 | } | |
1143 | ||
1144 | return max(smin, period); | |
1145 | } | |
1146 | ||
598f0ec0 MG |
1147 | static unsigned int task_scan_max(struct task_struct *p) |
1148 | { | |
b5dd77c8 RR |
1149 | unsigned long smin = task_scan_min(p); |
1150 | unsigned long smax; | |
598f0ec0 MG |
1151 | |
1152 | /* Watch for min being lower than max due to floor calculations */ | |
1153 | smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p); | |
b5dd77c8 RR |
1154 | |
1155 | /* Scale the maximum scan period with the amount of shared memory. */ | |
1156 | if (p->numa_group) { | |
1157 | struct numa_group *ng = p->numa_group; | |
1158 | unsigned long shared = group_faults_shared(ng); | |
1159 | unsigned long private = group_faults_priv(ng); | |
1160 | unsigned long period = smax; | |
1161 | ||
1162 | period *= atomic_read(&ng->refcount); | |
1163 | period *= shared + 1; | |
1164 | period /= private + shared + 1; | |
1165 | ||
1166 | smax = max(smax, period); | |
1167 | } | |
1168 | ||
598f0ec0 MG |
1169 | return max(smin, smax); |
1170 | } | |
1171 | ||
0ec8aa00 PZ |
1172 | static void account_numa_enqueue(struct rq *rq, struct task_struct *p) |
1173 | { | |
1174 | rq->nr_numa_running += (p->numa_preferred_nid != -1); | |
1175 | rq->nr_preferred_running += (p->numa_preferred_nid == task_node(p)); | |
1176 | } | |
1177 | ||
1178 | static void account_numa_dequeue(struct rq *rq, struct task_struct *p) | |
1179 | { | |
1180 | rq->nr_numa_running -= (p->numa_preferred_nid != -1); | |
1181 | rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p)); | |
1182 | } | |
1183 | ||
be1e4e76 RR |
1184 | /* Shared or private faults. */ |
1185 | #define NR_NUMA_HINT_FAULT_TYPES 2 | |
1186 | ||
1187 | /* Memory and CPU locality */ | |
1188 | #define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2) | |
1189 | ||
1190 | /* Averaged statistics, and temporary buffers. */ | |
1191 | #define NR_NUMA_HINT_FAULT_BUCKETS (NR_NUMA_HINT_FAULT_STATS * 2) | |
1192 | ||
e29cf08b MG |
1193 | pid_t task_numa_group_id(struct task_struct *p) |
1194 | { | |
1195 | return p->numa_group ? p->numa_group->gid : 0; | |
1196 | } | |
1197 | ||
44dba3d5 IM |
1198 | /* |
1199 | * The averaged statistics, shared & private, memory & cpu, | |
1200 | * occupy the first half of the array. The second half of the | |
1201 | * array is for current counters, which are averaged into the | |
1202 | * first set by task_numa_placement. | |
1203 | */ | |
1204 | static inline int task_faults_idx(enum numa_faults_stats s, int nid, int priv) | |
ac8e895b | 1205 | { |
44dba3d5 | 1206 | return NR_NUMA_HINT_FAULT_TYPES * (s * nr_node_ids + nid) + priv; |
ac8e895b MG |
1207 | } |
1208 | ||
1209 | static inline unsigned long task_faults(struct task_struct *p, int nid) | |
1210 | { | |
44dba3d5 | 1211 | if (!p->numa_faults) |
ac8e895b MG |
1212 | return 0; |
1213 | ||
44dba3d5 IM |
1214 | return p->numa_faults[task_faults_idx(NUMA_MEM, nid, 0)] + |
1215 | p->numa_faults[task_faults_idx(NUMA_MEM, nid, 1)]; | |
ac8e895b MG |
1216 | } |
1217 | ||
83e1d2cd MG |
1218 | static inline unsigned long group_faults(struct task_struct *p, int nid) |
1219 | { | |
1220 | if (!p->numa_group) | |
1221 | return 0; | |
1222 | ||
44dba3d5 IM |
1223 | return p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 0)] + |
1224 | p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 1)]; | |
83e1d2cd MG |
1225 | } |
1226 | ||
20e07dea RR |
1227 | static inline unsigned long group_faults_cpu(struct numa_group *group, int nid) |
1228 | { | |
44dba3d5 IM |
1229 | return group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 0)] + |
1230 | group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 1)]; | |
20e07dea RR |
1231 | } |
1232 | ||
b5dd77c8 RR |
1233 | static inline unsigned long group_faults_priv(struct numa_group *ng) |
1234 | { | |
1235 | unsigned long faults = 0; | |
1236 | int node; | |
1237 | ||
1238 | for_each_online_node(node) { | |
1239 | faults += ng->faults[task_faults_idx(NUMA_MEM, node, 1)]; | |
1240 | } | |
1241 | ||
1242 | return faults; | |
1243 | } | |
1244 | ||
1245 | static inline unsigned long group_faults_shared(struct numa_group *ng) | |
1246 | { | |
1247 | unsigned long faults = 0; | |
1248 | int node; | |
1249 | ||
1250 | for_each_online_node(node) { | |
1251 | faults += ng->faults[task_faults_idx(NUMA_MEM, node, 0)]; | |
1252 | } | |
1253 | ||
1254 | return faults; | |
1255 | } | |
1256 | ||
4142c3eb RR |
1257 | /* |
1258 | * A node triggering more than 1/3 as many NUMA faults as the maximum is | |
1259 | * considered part of a numa group's pseudo-interleaving set. Migrations | |
1260 | * between these nodes are slowed down, to allow things to settle down. | |
1261 | */ | |
1262 | #define ACTIVE_NODE_FRACTION 3 | |
1263 | ||
1264 | static bool numa_is_active_node(int nid, struct numa_group *ng) | |
1265 | { | |
1266 | return group_faults_cpu(ng, nid) * ACTIVE_NODE_FRACTION > ng->max_faults_cpu; | |
1267 | } | |
1268 | ||
6c6b1193 RR |
1269 | /* Handle placement on systems where not all nodes are directly connected. */ |
1270 | static unsigned long score_nearby_nodes(struct task_struct *p, int nid, | |
1271 | int maxdist, bool task) | |
1272 | { | |
1273 | unsigned long score = 0; | |
1274 | int node; | |
1275 | ||
1276 | /* | |
1277 | * All nodes are directly connected, and the same distance | |
1278 | * from each other. No need for fancy placement algorithms. | |
1279 | */ | |
1280 | if (sched_numa_topology_type == NUMA_DIRECT) | |
1281 | return 0; | |
1282 | ||
1283 | /* | |
1284 | * This code is called for each node, introducing N^2 complexity, | |
1285 | * which should be ok given the number of nodes rarely exceeds 8. | |
1286 | */ | |
1287 | for_each_online_node(node) { | |
1288 | unsigned long faults; | |
1289 | int dist = node_distance(nid, node); | |
1290 | ||
1291 | /* | |
1292 | * The furthest away nodes in the system are not interesting | |
1293 | * for placement; nid was already counted. | |
1294 | */ | |
1295 | if (dist == sched_max_numa_distance || node == nid) | |
1296 | continue; | |
1297 | ||
1298 | /* | |
1299 | * On systems with a backplane NUMA topology, compare groups | |
1300 | * of nodes, and move tasks towards the group with the most | |
1301 | * memory accesses. When comparing two nodes at distance | |
1302 | * "hoplimit", only nodes closer by than "hoplimit" are part | |
1303 | * of each group. Skip other nodes. | |
1304 | */ | |
1305 | if (sched_numa_topology_type == NUMA_BACKPLANE && | |
1306 | dist > maxdist) | |
1307 | continue; | |
1308 | ||
1309 | /* Add up the faults from nearby nodes. */ | |
1310 | if (task) | |
1311 | faults = task_faults(p, node); | |
1312 | else | |
1313 | faults = group_faults(p, node); | |
1314 | ||
1315 | /* | |
1316 | * On systems with a glueless mesh NUMA topology, there are | |
1317 | * no fixed "groups of nodes". Instead, nodes that are not | |
1318 | * directly connected bounce traffic through intermediate | |
1319 | * nodes; a numa_group can occupy any set of nodes. | |
1320 | * The further away a node is, the less the faults count. | |
1321 | * This seems to result in good task placement. | |
1322 | */ | |
1323 | if (sched_numa_topology_type == NUMA_GLUELESS_MESH) { | |
1324 | faults *= (sched_max_numa_distance - dist); | |
1325 | faults /= (sched_max_numa_distance - LOCAL_DISTANCE); | |
1326 | } | |
1327 | ||
1328 | score += faults; | |
1329 | } | |
1330 | ||
1331 | return score; | |
1332 | } | |
1333 | ||
83e1d2cd MG |
1334 | /* |
1335 | * These return the fraction of accesses done by a particular task, or | |
1336 | * task group, on a particular numa node. The group weight is given a | |
1337 | * larger multiplier, in order to group tasks together that are almost | |
1338 | * evenly spread out between numa nodes. | |
1339 | */ | |
7bd95320 RR |
1340 | static inline unsigned long task_weight(struct task_struct *p, int nid, |
1341 | int dist) | |
83e1d2cd | 1342 | { |
7bd95320 | 1343 | unsigned long faults, total_faults; |
83e1d2cd | 1344 | |
44dba3d5 | 1345 | if (!p->numa_faults) |
83e1d2cd MG |
1346 | return 0; |
1347 | ||
1348 | total_faults = p->total_numa_faults; | |
1349 | ||
1350 | if (!total_faults) | |
1351 | return 0; | |
1352 | ||
7bd95320 | 1353 | faults = task_faults(p, nid); |
6c6b1193 RR |
1354 | faults += score_nearby_nodes(p, nid, dist, true); |
1355 | ||
7bd95320 | 1356 | return 1000 * faults / total_faults; |
83e1d2cd MG |
1357 | } |
1358 | ||
7bd95320 RR |
1359 | static inline unsigned long group_weight(struct task_struct *p, int nid, |
1360 | int dist) | |
83e1d2cd | 1361 | { |
7bd95320 RR |
1362 | unsigned long faults, total_faults; |
1363 | ||
1364 | if (!p->numa_group) | |
1365 | return 0; | |
1366 | ||
1367 | total_faults = p->numa_group->total_faults; | |
1368 | ||
1369 | if (!total_faults) | |
83e1d2cd MG |
1370 | return 0; |
1371 | ||
7bd95320 | 1372 | faults = group_faults(p, nid); |
6c6b1193 RR |
1373 | faults += score_nearby_nodes(p, nid, dist, false); |
1374 | ||
7bd95320 | 1375 | return 1000 * faults / total_faults; |
83e1d2cd MG |
1376 | } |
1377 | ||
10f39042 RR |
1378 | bool should_numa_migrate_memory(struct task_struct *p, struct page * page, |
1379 | int src_nid, int dst_cpu) | |
1380 | { | |
1381 | struct numa_group *ng = p->numa_group; | |
1382 | int dst_nid = cpu_to_node(dst_cpu); | |
1383 | int last_cpupid, this_cpupid; | |
1384 | ||
1385 | this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid); | |
1386 | ||
1387 | /* | |
1388 | * Multi-stage node selection is used in conjunction with a periodic | |
1389 | * migration fault to build a temporal task<->page relation. By using | |
1390 | * a two-stage filter we remove short/unlikely relations. | |
1391 | * | |
1392 | * Using P(p) ~ n_p / n_t as per frequentist probability, we can equate | |
1393 | * a task's usage of a particular page (n_p) per total usage of this | |
1394 | * page (n_t) (in a given time-span) to a probability. | |
1395 | * | |
1396 | * Our periodic faults will sample this probability and getting the | |
1397 | * same result twice in a row, given these samples are fully | |
1398 | * independent, is then given by P(n)^2, provided our sample period | |
1399 | * is sufficiently short compared to the usage pattern. | |
1400 | * | |
1401 | * This quadric squishes small probabilities, making it less likely we | |
1402 | * act on an unlikely task<->page relation. | |
1403 | */ | |
1404 | last_cpupid = page_cpupid_xchg_last(page, this_cpupid); | |
1405 | if (!cpupid_pid_unset(last_cpupid) && | |
1406 | cpupid_to_nid(last_cpupid) != dst_nid) | |
1407 | return false; | |
1408 | ||
1409 | /* Always allow migrate on private faults */ | |
1410 | if (cpupid_match_pid(p, last_cpupid)) | |
1411 | return true; | |
1412 | ||
1413 | /* A shared fault, but p->numa_group has not been set up yet. */ | |
1414 | if (!ng) | |
1415 | return true; | |
1416 | ||
1417 | /* | |
4142c3eb RR |
1418 | * Destination node is much more heavily used than the source |
1419 | * node? Allow migration. | |
10f39042 | 1420 | */ |
4142c3eb RR |
1421 | if (group_faults_cpu(ng, dst_nid) > group_faults_cpu(ng, src_nid) * |
1422 | ACTIVE_NODE_FRACTION) | |
10f39042 RR |
1423 | return true; |
1424 | ||
1425 | /* | |
4142c3eb RR |
1426 | * Distribute memory according to CPU & memory use on each node, |
1427 | * with 3/4 hysteresis to avoid unnecessary memory migrations: | |
1428 | * | |
1429 | * faults_cpu(dst) 3 faults_cpu(src) | |
1430 | * --------------- * - > --------------- | |
1431 | * faults_mem(dst) 4 faults_mem(src) | |
10f39042 | 1432 | */ |
4142c3eb RR |
1433 | return group_faults_cpu(ng, dst_nid) * group_faults(p, src_nid) * 3 > |
1434 | group_faults_cpu(ng, src_nid) * group_faults(p, dst_nid) * 4; | |
10f39042 RR |
1435 | } |
1436 | ||
c7132dd6 | 1437 | static unsigned long weighted_cpuload(struct rq *rq); |
58d081b5 MG |
1438 | static unsigned long source_load(int cpu, int type); |
1439 | static unsigned long target_load(int cpu, int type); | |
ced549fa | 1440 | static unsigned long capacity_of(int cpu); |
58d081b5 | 1441 | |
fb13c7ee | 1442 | /* Cached statistics for all CPUs within a node */ |
58d081b5 | 1443 | struct numa_stats { |
fb13c7ee | 1444 | unsigned long nr_running; |
58d081b5 | 1445 | unsigned long load; |
fb13c7ee MG |
1446 | |
1447 | /* Total compute capacity of CPUs on a node */ | |
5ef20ca1 | 1448 | unsigned long compute_capacity; |
fb13c7ee MG |
1449 | |
1450 | /* Approximate capacity in terms of runnable tasks on a node */ | |
5ef20ca1 | 1451 | unsigned long task_capacity; |
1b6a7495 | 1452 | int has_free_capacity; |
58d081b5 | 1453 | }; |
e6628d5b | 1454 | |
fb13c7ee MG |
1455 | /* |
1456 | * XXX borrowed from update_sg_lb_stats | |
1457 | */ | |
1458 | static void update_numa_stats(struct numa_stats *ns, int nid) | |
1459 | { | |
83d7f242 RR |
1460 | int smt, cpu, cpus = 0; |
1461 | unsigned long capacity; | |
fb13c7ee MG |
1462 | |
1463 | memset(ns, 0, sizeof(*ns)); | |
1464 | for_each_cpu(cpu, cpumask_of_node(nid)) { | |
1465 | struct rq *rq = cpu_rq(cpu); | |
1466 | ||
1467 | ns->nr_running += rq->nr_running; | |
c7132dd6 | 1468 | ns->load += weighted_cpuload(rq); |
ced549fa | 1469 | ns->compute_capacity += capacity_of(cpu); |
5eca82a9 PZ |
1470 | |
1471 | cpus++; | |
fb13c7ee MG |
1472 | } |
1473 | ||
5eca82a9 PZ |
1474 | /* |
1475 | * If we raced with hotplug and there are no CPUs left in our mask | |
1476 | * the @ns structure is NULL'ed and task_numa_compare() will | |
1477 | * not find this node attractive. | |
1478 | * | |
1b6a7495 NP |
1479 | * We'll either bail at !has_free_capacity, or we'll detect a huge |
1480 | * imbalance and bail there. | |
5eca82a9 PZ |
1481 | */ |
1482 | if (!cpus) | |
1483 | return; | |
1484 | ||
83d7f242 RR |
1485 | /* smt := ceil(cpus / capacity), assumes: 1 < smt_power < 2 */ |
1486 | smt = DIV_ROUND_UP(SCHED_CAPACITY_SCALE * cpus, ns->compute_capacity); | |
1487 | capacity = cpus / smt; /* cores */ | |
1488 | ||
1489 | ns->task_capacity = min_t(unsigned, capacity, | |
1490 | DIV_ROUND_CLOSEST(ns->compute_capacity, SCHED_CAPACITY_SCALE)); | |
1b6a7495 | 1491 | ns->has_free_capacity = (ns->nr_running < ns->task_capacity); |
fb13c7ee MG |
1492 | } |
1493 | ||
58d081b5 MG |
1494 | struct task_numa_env { |
1495 | struct task_struct *p; | |
e6628d5b | 1496 | |
58d081b5 MG |
1497 | int src_cpu, src_nid; |
1498 | int dst_cpu, dst_nid; | |
e6628d5b | 1499 | |
58d081b5 | 1500 | struct numa_stats src_stats, dst_stats; |
e6628d5b | 1501 | |
40ea2b42 | 1502 | int imbalance_pct; |
7bd95320 | 1503 | int dist; |
fb13c7ee MG |
1504 | |
1505 | struct task_struct *best_task; | |
1506 | long best_imp; | |
58d081b5 MG |
1507 | int best_cpu; |
1508 | }; | |
1509 | ||
fb13c7ee MG |
1510 | static void task_numa_assign(struct task_numa_env *env, |
1511 | struct task_struct *p, long imp) | |
1512 | { | |
1513 | if (env->best_task) | |
1514 | put_task_struct(env->best_task); | |
bac78573 ON |
1515 | if (p) |
1516 | get_task_struct(p); | |
fb13c7ee MG |
1517 | |
1518 | env->best_task = p; | |
1519 | env->best_imp = imp; | |
1520 | env->best_cpu = env->dst_cpu; | |
1521 | } | |
1522 | ||
28a21745 | 1523 | static bool load_too_imbalanced(long src_load, long dst_load, |
e63da036 RR |
1524 | struct task_numa_env *env) |
1525 | { | |
e4991b24 RR |
1526 | long imb, old_imb; |
1527 | long orig_src_load, orig_dst_load; | |
28a21745 RR |
1528 | long src_capacity, dst_capacity; |
1529 | ||
1530 | /* | |
1531 | * The load is corrected for the CPU capacity available on each node. | |
1532 | * | |
1533 | * src_load dst_load | |
1534 | * ------------ vs --------- | |
1535 | * src_capacity dst_capacity | |
1536 | */ | |
1537 | src_capacity = env->src_stats.compute_capacity; | |
1538 | dst_capacity = env->dst_stats.compute_capacity; | |
e63da036 RR |
1539 | |
1540 | /* We care about the slope of the imbalance, not the direction. */ | |
e4991b24 RR |
1541 | if (dst_load < src_load) |
1542 | swap(dst_load, src_load); | |
e63da036 RR |
1543 | |
1544 | /* Is the difference below the threshold? */ | |
e4991b24 RR |
1545 | imb = dst_load * src_capacity * 100 - |
1546 | src_load * dst_capacity * env->imbalance_pct; | |
e63da036 RR |
1547 | if (imb <= 0) |
1548 | return false; | |
1549 | ||
1550 | /* | |
1551 | * The imbalance is above the allowed threshold. | |
e4991b24 | 1552 | * Compare it with the old imbalance. |
e63da036 | 1553 | */ |
28a21745 | 1554 | orig_src_load = env->src_stats.load; |
e4991b24 | 1555 | orig_dst_load = env->dst_stats.load; |
28a21745 | 1556 | |
e4991b24 RR |
1557 | if (orig_dst_load < orig_src_load) |
1558 | swap(orig_dst_load, orig_src_load); | |
e63da036 | 1559 | |
e4991b24 RR |
1560 | old_imb = orig_dst_load * src_capacity * 100 - |
1561 | orig_src_load * dst_capacity * env->imbalance_pct; | |
1562 | ||
1563 | /* Would this change make things worse? */ | |
1564 | return (imb > old_imb); | |
e63da036 RR |
1565 | } |
1566 | ||
fb13c7ee MG |
1567 | /* |
1568 | * This checks if the overall compute and NUMA accesses of the system would | |
1569 | * be improved if the source tasks was migrated to the target dst_cpu taking | |
1570 | * into account that it might be best if task running on the dst_cpu should | |
1571 | * be exchanged with the source task | |
1572 | */ | |
887c290e RR |
1573 | static void task_numa_compare(struct task_numa_env *env, |
1574 | long taskimp, long groupimp) | |
fb13c7ee MG |
1575 | { |
1576 | struct rq *src_rq = cpu_rq(env->src_cpu); | |
1577 | struct rq *dst_rq = cpu_rq(env->dst_cpu); | |
1578 | struct task_struct *cur; | |
28a21745 | 1579 | long src_load, dst_load; |
fb13c7ee | 1580 | long load; |
1c5d3eb3 | 1581 | long imp = env->p->numa_group ? groupimp : taskimp; |
0132c3e1 | 1582 | long moveimp = imp; |
7bd95320 | 1583 | int dist = env->dist; |
fb13c7ee MG |
1584 | |
1585 | rcu_read_lock(); | |
bac78573 ON |
1586 | cur = task_rcu_dereference(&dst_rq->curr); |
1587 | if (cur && ((cur->flags & PF_EXITING) || is_idle_task(cur))) | |
fb13c7ee MG |
1588 | cur = NULL; |
1589 | ||
7af68335 PZ |
1590 | /* |
1591 | * Because we have preemption enabled we can get migrated around and | |
1592 | * end try selecting ourselves (current == env->p) as a swap candidate. | |
1593 | */ | |
1594 | if (cur == env->p) | |
1595 | goto unlock; | |
1596 | ||
fb13c7ee MG |
1597 | /* |
1598 | * "imp" is the fault differential for the source task between the | |
1599 | * source and destination node. Calculate the total differential for | |
1600 | * the source task and potential destination task. The more negative | |
1601 | * the value is, the more rmeote accesses that would be expected to | |
1602 | * be incurred if the tasks were swapped. | |
1603 | */ | |
1604 | if (cur) { | |
1605 | /* Skip this swap candidate if cannot move to the source cpu */ | |
0c98d344 | 1606 | if (!cpumask_test_cpu(env->src_cpu, &cur->cpus_allowed)) |
fb13c7ee MG |
1607 | goto unlock; |
1608 | ||
887c290e RR |
1609 | /* |
1610 | * If dst and source tasks are in the same NUMA group, or not | |
ca28aa53 | 1611 | * in any group then look only at task weights. |
887c290e | 1612 | */ |
ca28aa53 | 1613 | if (cur->numa_group == env->p->numa_group) { |
7bd95320 RR |
1614 | imp = taskimp + task_weight(cur, env->src_nid, dist) - |
1615 | task_weight(cur, env->dst_nid, dist); | |
ca28aa53 RR |
1616 | /* |
1617 | * Add some hysteresis to prevent swapping the | |
1618 | * tasks within a group over tiny differences. | |
1619 | */ | |
1620 | if (cur->numa_group) | |
1621 | imp -= imp/16; | |
887c290e | 1622 | } else { |
ca28aa53 RR |
1623 | /* |
1624 | * Compare the group weights. If a task is all by | |
1625 | * itself (not part of a group), use the task weight | |
1626 | * instead. | |
1627 | */ | |
ca28aa53 | 1628 | if (cur->numa_group) |
7bd95320 RR |
1629 | imp += group_weight(cur, env->src_nid, dist) - |
1630 | group_weight(cur, env->dst_nid, dist); | |
ca28aa53 | 1631 | else |
7bd95320 RR |
1632 | imp += task_weight(cur, env->src_nid, dist) - |
1633 | task_weight(cur, env->dst_nid, dist); | |
887c290e | 1634 | } |
fb13c7ee MG |
1635 | } |
1636 | ||
0132c3e1 | 1637 | if (imp <= env->best_imp && moveimp <= env->best_imp) |
fb13c7ee MG |
1638 | goto unlock; |
1639 | ||
1640 | if (!cur) { | |
1641 | /* Is there capacity at our destination? */ | |
b932c03c | 1642 | if (env->src_stats.nr_running <= env->src_stats.task_capacity && |
1b6a7495 | 1643 | !env->dst_stats.has_free_capacity) |
fb13c7ee MG |
1644 | goto unlock; |
1645 | ||
1646 | goto balance; | |
1647 | } | |
1648 | ||
1649 | /* Balance doesn't matter much if we're running a task per cpu */ | |
0132c3e1 RR |
1650 | if (imp > env->best_imp && src_rq->nr_running == 1 && |
1651 | dst_rq->nr_running == 1) | |
fb13c7ee MG |
1652 | goto assign; |
1653 | ||
1654 | /* | |
1655 | * In the overloaded case, try and keep the load balanced. | |
1656 | */ | |
1657 | balance: | |
e720fff6 PZ |
1658 | load = task_h_load(env->p); |
1659 | dst_load = env->dst_stats.load + load; | |
1660 | src_load = env->src_stats.load - load; | |
fb13c7ee | 1661 | |
0132c3e1 RR |
1662 | if (moveimp > imp && moveimp > env->best_imp) { |
1663 | /* | |
1664 | * If the improvement from just moving env->p direction is | |
1665 | * better than swapping tasks around, check if a move is | |
1666 | * possible. Store a slightly smaller score than moveimp, | |
1667 | * so an actually idle CPU will win. | |
1668 | */ | |
1669 | if (!load_too_imbalanced(src_load, dst_load, env)) { | |
1670 | imp = moveimp - 1; | |
1671 | cur = NULL; | |
1672 | goto assign; | |
1673 | } | |
1674 | } | |
1675 | ||
1676 | if (imp <= env->best_imp) | |
1677 | goto unlock; | |
1678 | ||
fb13c7ee | 1679 | if (cur) { |
e720fff6 PZ |
1680 | load = task_h_load(cur); |
1681 | dst_load -= load; | |
1682 | src_load += load; | |
fb13c7ee MG |
1683 | } |
1684 | ||
28a21745 | 1685 | if (load_too_imbalanced(src_load, dst_load, env)) |
fb13c7ee MG |
1686 | goto unlock; |
1687 | ||
ba7e5a27 RR |
1688 | /* |
1689 | * One idle CPU per node is evaluated for a task numa move. | |
1690 | * Call select_idle_sibling to maybe find a better one. | |
1691 | */ | |
10e2f1ac PZ |
1692 | if (!cur) { |
1693 | /* | |
1694 | * select_idle_siblings() uses an per-cpu cpumask that | |
1695 | * can be used from IRQ context. | |
1696 | */ | |
1697 | local_irq_disable(); | |
772bd008 MR |
1698 | env->dst_cpu = select_idle_sibling(env->p, env->src_cpu, |
1699 | env->dst_cpu); | |
10e2f1ac PZ |
1700 | local_irq_enable(); |
1701 | } | |
ba7e5a27 | 1702 | |
fb13c7ee MG |
1703 | assign: |
1704 | task_numa_assign(env, cur, imp); | |
1705 | unlock: | |
1706 | rcu_read_unlock(); | |
1707 | } | |
1708 | ||
887c290e RR |
1709 | static void task_numa_find_cpu(struct task_numa_env *env, |
1710 | long taskimp, long groupimp) | |
2c8a50aa MG |
1711 | { |
1712 | int cpu; | |
1713 | ||
1714 | for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) { | |
1715 | /* Skip this CPU if the source task cannot migrate */ | |
0c98d344 | 1716 | if (!cpumask_test_cpu(cpu, &env->p->cpus_allowed)) |
2c8a50aa MG |
1717 | continue; |
1718 | ||
1719 | env->dst_cpu = cpu; | |
887c290e | 1720 | task_numa_compare(env, taskimp, groupimp); |
2c8a50aa MG |
1721 | } |
1722 | } | |
1723 | ||
6f9aad0b RR |
1724 | /* Only move tasks to a NUMA node less busy than the current node. */ |
1725 | static bool numa_has_capacity(struct task_numa_env *env) | |
1726 | { | |
1727 | struct numa_stats *src = &env->src_stats; | |
1728 | struct numa_stats *dst = &env->dst_stats; | |
1729 | ||
1730 | if (src->has_free_capacity && !dst->has_free_capacity) | |
1731 | return false; | |
1732 | ||
1733 | /* | |
1734 | * Only consider a task move if the source has a higher load | |
1735 | * than the destination, corrected for CPU capacity on each node. | |
1736 | * | |
1737 | * src->load dst->load | |
1738 | * --------------------- vs --------------------- | |
1739 | * src->compute_capacity dst->compute_capacity | |
1740 | */ | |
44dcb04f SD |
1741 | if (src->load * dst->compute_capacity * env->imbalance_pct > |
1742 | ||
1743 | dst->load * src->compute_capacity * 100) | |
6f9aad0b RR |
1744 | return true; |
1745 | ||
1746 | return false; | |
1747 | } | |
1748 | ||
58d081b5 MG |
1749 | static int task_numa_migrate(struct task_struct *p) |
1750 | { | |
58d081b5 MG |
1751 | struct task_numa_env env = { |
1752 | .p = p, | |
fb13c7ee | 1753 | |
58d081b5 | 1754 | .src_cpu = task_cpu(p), |
b32e86b4 | 1755 | .src_nid = task_node(p), |
fb13c7ee MG |
1756 | |
1757 | .imbalance_pct = 112, | |
1758 | ||
1759 | .best_task = NULL, | |
1760 | .best_imp = 0, | |
4142c3eb | 1761 | .best_cpu = -1, |
58d081b5 MG |
1762 | }; |
1763 | struct sched_domain *sd; | |
887c290e | 1764 | unsigned long taskweight, groupweight; |
7bd95320 | 1765 | int nid, ret, dist; |
887c290e | 1766 | long taskimp, groupimp; |
e6628d5b | 1767 | |
58d081b5 | 1768 | /* |
fb13c7ee MG |
1769 | * Pick the lowest SD_NUMA domain, as that would have the smallest |
1770 | * imbalance and would be the first to start moving tasks about. | |
1771 | * | |
1772 | * And we want to avoid any moving of tasks about, as that would create | |
1773 | * random movement of tasks -- counter the numa conditions we're trying | |
1774 | * to satisfy here. | |
58d081b5 MG |
1775 | */ |
1776 | rcu_read_lock(); | |
fb13c7ee | 1777 | sd = rcu_dereference(per_cpu(sd_numa, env.src_cpu)); |
46a73e8a RR |
1778 | if (sd) |
1779 | env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2; | |
e6628d5b MG |
1780 | rcu_read_unlock(); |
1781 | ||
46a73e8a RR |
1782 | /* |
1783 | * Cpusets can break the scheduler domain tree into smaller | |
1784 | * balance domains, some of which do not cross NUMA boundaries. | |
1785 | * Tasks that are "trapped" in such domains cannot be migrated | |
1786 | * elsewhere, so there is no point in (re)trying. | |
1787 | */ | |
1788 | if (unlikely(!sd)) { | |
de1b301a | 1789 | p->numa_preferred_nid = task_node(p); |
46a73e8a RR |
1790 | return -EINVAL; |
1791 | } | |
1792 | ||
2c8a50aa | 1793 | env.dst_nid = p->numa_preferred_nid; |
7bd95320 RR |
1794 | dist = env.dist = node_distance(env.src_nid, env.dst_nid); |
1795 | taskweight = task_weight(p, env.src_nid, dist); | |
1796 | groupweight = group_weight(p, env.src_nid, dist); | |
1797 | update_numa_stats(&env.src_stats, env.src_nid); | |
1798 | taskimp = task_weight(p, env.dst_nid, dist) - taskweight; | |
1799 | groupimp = group_weight(p, env.dst_nid, dist) - groupweight; | |
2c8a50aa | 1800 | update_numa_stats(&env.dst_stats, env.dst_nid); |
58d081b5 | 1801 | |
a43455a1 | 1802 | /* Try to find a spot on the preferred nid. */ |
6f9aad0b RR |
1803 | if (numa_has_capacity(&env)) |
1804 | task_numa_find_cpu(&env, taskimp, groupimp); | |
e1dda8a7 | 1805 | |
9de05d48 RR |
1806 | /* |
1807 | * Look at other nodes in these cases: | |
1808 | * - there is no space available on the preferred_nid | |
1809 | * - the task is part of a numa_group that is interleaved across | |
1810 | * multiple NUMA nodes; in order to better consolidate the group, | |
1811 | * we need to check other locations. | |
1812 | */ | |
4142c3eb | 1813 | if (env.best_cpu == -1 || (p->numa_group && p->numa_group->active_nodes > 1)) { |
2c8a50aa MG |
1814 | for_each_online_node(nid) { |
1815 | if (nid == env.src_nid || nid == p->numa_preferred_nid) | |
1816 | continue; | |
58d081b5 | 1817 | |
7bd95320 | 1818 | dist = node_distance(env.src_nid, env.dst_nid); |
6c6b1193 RR |
1819 | if (sched_numa_topology_type == NUMA_BACKPLANE && |
1820 | dist != env.dist) { | |
1821 | taskweight = task_weight(p, env.src_nid, dist); | |
1822 | groupweight = group_weight(p, env.src_nid, dist); | |
1823 | } | |
7bd95320 | 1824 | |
83e1d2cd | 1825 | /* Only consider nodes where both task and groups benefit */ |
7bd95320 RR |
1826 | taskimp = task_weight(p, nid, dist) - taskweight; |
1827 | groupimp = group_weight(p, nid, dist) - groupweight; | |
887c290e | 1828 | if (taskimp < 0 && groupimp < 0) |
fb13c7ee MG |
1829 | continue; |
1830 | ||
7bd95320 | 1831 | env.dist = dist; |
2c8a50aa MG |
1832 | env.dst_nid = nid; |
1833 | update_numa_stats(&env.dst_stats, env.dst_nid); | |
6f9aad0b RR |
1834 | if (numa_has_capacity(&env)) |
1835 | task_numa_find_cpu(&env, taskimp, groupimp); | |
58d081b5 MG |
1836 | } |
1837 | } | |
1838 | ||
68d1b02a RR |
1839 | /* |
1840 | * If the task is part of a workload that spans multiple NUMA nodes, | |
1841 | * and is migrating into one of the workload's active nodes, remember | |
1842 | * this node as the task's preferred numa node, so the workload can | |
1843 | * settle down. | |
1844 | * A task that migrated to a second choice node will be better off | |
1845 | * trying for a better one later. Do not set the preferred node here. | |
1846 | */ | |
db015dae | 1847 | if (p->numa_group) { |
4142c3eb RR |
1848 | struct numa_group *ng = p->numa_group; |
1849 | ||
db015dae RR |
1850 | if (env.best_cpu == -1) |
1851 | nid = env.src_nid; | |
1852 | else | |
1853 | nid = env.dst_nid; | |
1854 | ||
4142c3eb | 1855 | if (ng->active_nodes > 1 && numa_is_active_node(env.dst_nid, ng)) |
db015dae RR |
1856 | sched_setnuma(p, env.dst_nid); |
1857 | } | |
1858 | ||
1859 | /* No better CPU than the current one was found. */ | |
1860 | if (env.best_cpu == -1) | |
1861 | return -EAGAIN; | |
0ec8aa00 | 1862 | |
04bb2f94 RR |
1863 | /* |
1864 | * Reset the scan period if the task is being rescheduled on an | |
1865 | * alternative node to recheck if the tasks is now properly placed. | |
1866 | */ | |
b5dd77c8 | 1867 | p->numa_scan_period = task_scan_start(p); |
04bb2f94 | 1868 | |
fb13c7ee | 1869 | if (env.best_task == NULL) { |
286549dc MG |
1870 | ret = migrate_task_to(p, env.best_cpu); |
1871 | if (ret != 0) | |
1872 | trace_sched_stick_numa(p, env.src_cpu, env.best_cpu); | |
fb13c7ee MG |
1873 | return ret; |
1874 | } | |
1875 | ||
1876 | ret = migrate_swap(p, env.best_task); | |
286549dc MG |
1877 | if (ret != 0) |
1878 | trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task)); | |
fb13c7ee MG |
1879 | put_task_struct(env.best_task); |
1880 | return ret; | |
e6628d5b MG |
1881 | } |
1882 | ||
6b9a7460 MG |
1883 | /* Attempt to migrate a task to a CPU on the preferred node. */ |
1884 | static void numa_migrate_preferred(struct task_struct *p) | |
1885 | { | |
5085e2a3 RR |
1886 | unsigned long interval = HZ; |
1887 | ||
2739d3ee | 1888 | /* This task has no NUMA fault statistics yet */ |
44dba3d5 | 1889 | if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults)) |
6b9a7460 MG |
1890 | return; |
1891 | ||
2739d3ee | 1892 | /* Periodically retry migrating the task to the preferred node */ |
5085e2a3 RR |
1893 | interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16); |
1894 | p->numa_migrate_retry = jiffies + interval; | |
2739d3ee RR |
1895 | |
1896 | /* Success if task is already running on preferred CPU */ | |
de1b301a | 1897 | if (task_node(p) == p->numa_preferred_nid) |
6b9a7460 MG |
1898 | return; |
1899 | ||
1900 | /* Otherwise, try migrate to a CPU on the preferred node */ | |
2739d3ee | 1901 | task_numa_migrate(p); |
6b9a7460 MG |
1902 | } |
1903 | ||
20e07dea | 1904 | /* |
4142c3eb | 1905 | * Find out how many nodes on the workload is actively running on. Do this by |
20e07dea RR |
1906 | * tracking the nodes from which NUMA hinting faults are triggered. This can |
1907 | * be different from the set of nodes where the workload's memory is currently | |
1908 | * located. | |
20e07dea | 1909 | */ |
4142c3eb | 1910 | static void numa_group_count_active_nodes(struct numa_group *numa_group) |
20e07dea RR |
1911 | { |
1912 | unsigned long faults, max_faults = 0; | |
4142c3eb | 1913 | int nid, active_nodes = 0; |
20e07dea RR |
1914 | |
1915 | for_each_online_node(nid) { | |
1916 | faults = group_faults_cpu(numa_group, nid); | |
1917 | if (faults > max_faults) | |
1918 | max_faults = faults; | |
1919 | } | |
1920 | ||
1921 | for_each_online_node(nid) { | |
1922 | faults = group_faults_cpu(numa_group, nid); | |
4142c3eb RR |
1923 | if (faults * ACTIVE_NODE_FRACTION > max_faults) |
1924 | active_nodes++; | |
20e07dea | 1925 | } |
4142c3eb RR |
1926 | |
1927 | numa_group->max_faults_cpu = max_faults; | |
1928 | numa_group->active_nodes = active_nodes; | |
20e07dea RR |
1929 | } |
1930 | ||
04bb2f94 RR |
1931 | /* |
1932 | * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS | |
1933 | * increments. The more local the fault statistics are, the higher the scan | |
a22b4b01 RR |
1934 | * period will be for the next scan window. If local/(local+remote) ratio is |
1935 | * below NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS) | |
1936 | * the scan period will decrease. Aim for 70% local accesses. | |
04bb2f94 RR |
1937 | */ |
1938 | #define NUMA_PERIOD_SLOTS 10 | |
a22b4b01 | 1939 | #define NUMA_PERIOD_THRESHOLD 7 |
04bb2f94 RR |
1940 | |
1941 | /* | |
1942 | * Increase the scan period (slow down scanning) if the majority of | |
1943 | * our memory is already on our local node, or if the majority of | |
1944 | * the page accesses are shared with other processes. | |
1945 | * Otherwise, decrease the scan period. | |
1946 | */ | |
1947 | static void update_task_scan_period(struct task_struct *p, | |
1948 | unsigned long shared, unsigned long private) | |
1949 | { | |
1950 | unsigned int period_slot; | |
37ec97de | 1951 | int lr_ratio, ps_ratio; |
04bb2f94 RR |
1952 | int diff; |
1953 | ||
1954 | unsigned long remote = p->numa_faults_locality[0]; | |
1955 | unsigned long local = p->numa_faults_locality[1]; | |
1956 | ||
1957 | /* | |
1958 | * If there were no record hinting faults then either the task is | |
1959 | * completely idle or all activity is areas that are not of interest | |
074c2381 MG |
1960 | * to automatic numa balancing. Related to that, if there were failed |
1961 | * migration then it implies we are migrating too quickly or the local | |
1962 | * node is overloaded. In either case, scan slower | |
04bb2f94 | 1963 | */ |
074c2381 | 1964 | if (local + shared == 0 || p->numa_faults_locality[2]) { |
04bb2f94 RR |
1965 | p->numa_scan_period = min(p->numa_scan_period_max, |
1966 | p->numa_scan_period << 1); | |
1967 | ||
1968 | p->mm->numa_next_scan = jiffies + | |
1969 | msecs_to_jiffies(p->numa_scan_period); | |
1970 | ||
1971 | return; | |
1972 | } | |
1973 | ||
1974 | /* | |
1975 | * Prepare to scale scan period relative to the current period. | |
1976 | * == NUMA_PERIOD_THRESHOLD scan period stays the same | |
1977 | * < NUMA_PERIOD_THRESHOLD scan period decreases (scan faster) | |
1978 | * >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower) | |
1979 | */ | |
1980 | period_slot = DIV_ROUND_UP(p->numa_scan_period, NUMA_PERIOD_SLOTS); | |
37ec97de RR |
1981 | lr_ratio = (local * NUMA_PERIOD_SLOTS) / (local + remote); |
1982 | ps_ratio = (private * NUMA_PERIOD_SLOTS) / (private + shared); | |
1983 | ||
1984 | if (ps_ratio >= NUMA_PERIOD_THRESHOLD) { | |
1985 | /* | |
1986 | * Most memory accesses are local. There is no need to | |
1987 | * do fast NUMA scanning, since memory is already local. | |
1988 | */ | |
1989 | int slot = ps_ratio - NUMA_PERIOD_THRESHOLD; | |
1990 | if (!slot) | |
1991 | slot = 1; | |
1992 | diff = slot * period_slot; | |
1993 | } else if (lr_ratio >= NUMA_PERIOD_THRESHOLD) { | |
1994 | /* | |
1995 | * Most memory accesses are shared with other tasks. | |
1996 | * There is no point in continuing fast NUMA scanning, | |
1997 | * since other tasks may just move the memory elsewhere. | |
1998 | */ | |
1999 | int slot = lr_ratio - NUMA_PERIOD_THRESHOLD; | |
04bb2f94 RR |
2000 | if (!slot) |
2001 | slot = 1; | |
2002 | diff = slot * period_slot; | |
2003 | } else { | |
04bb2f94 | 2004 | /* |
37ec97de RR |
2005 | * Private memory faults exceed (SLOTS-THRESHOLD)/SLOTS, |
2006 | * yet they are not on the local NUMA node. Speed up | |
2007 | * NUMA scanning to get the memory moved over. | |
04bb2f94 | 2008 | */ |
37ec97de RR |
2009 | int ratio = max(lr_ratio, ps_ratio); |
2010 | diff = -(NUMA_PERIOD_THRESHOLD - ratio) * period_slot; | |
04bb2f94 RR |
2011 | } |
2012 | ||
2013 | p->numa_scan_period = clamp(p->numa_scan_period + diff, | |
2014 | task_scan_min(p), task_scan_max(p)); | |
2015 | memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); | |
2016 | } | |
2017 | ||
7e2703e6 RR |
2018 | /* |
2019 | * Get the fraction of time the task has been running since the last | |
2020 | * NUMA placement cycle. The scheduler keeps similar statistics, but | |
2021 | * decays those on a 32ms period, which is orders of magnitude off | |
2022 | * from the dozens-of-seconds NUMA balancing period. Use the scheduler | |
2023 | * stats only if the task is so new there are no NUMA statistics yet. | |
2024 | */ | |
2025 | static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period) | |
2026 | { | |
2027 | u64 runtime, delta, now; | |
2028 | /* Use the start of this time slice to avoid calculations. */ | |
2029 | now = p->se.exec_start; | |
2030 | runtime = p->se.sum_exec_runtime; | |
2031 | ||
2032 | if (p->last_task_numa_placement) { | |
2033 | delta = runtime - p->last_sum_exec_runtime; | |
2034 | *period = now - p->last_task_numa_placement; | |
0162ce49 XX |
2035 | |
2036 | /* Avoid time going backwards, prevent potential divide error: */ | |
2037 | if (unlikely((s64)*period < 0)) | |
2038 | *period = 0; | |
7e2703e6 | 2039 | } else { |
c7b50216 | 2040 | delta = p->se.avg.load_sum; |
9d89c257 | 2041 | *period = LOAD_AVG_MAX; |
7e2703e6 RR |
2042 | } |
2043 | ||
2044 | p->last_sum_exec_runtime = runtime; | |
2045 | p->last_task_numa_placement = now; | |
2046 | ||
2047 | return delta; | |
2048 | } | |
2049 | ||
54009416 RR |
2050 | /* |
2051 | * Determine the preferred nid for a task in a numa_group. This needs to | |
2052 | * be done in a way that produces consistent results with group_weight, | |
2053 | * otherwise workloads might not converge. | |
2054 | */ | |
2055 | static int preferred_group_nid(struct task_struct *p, int nid) | |
2056 | { | |
2057 | nodemask_t nodes; | |
2058 | int dist; | |
2059 | ||
2060 | /* Direct connections between all NUMA nodes. */ | |
2061 | if (sched_numa_topology_type == NUMA_DIRECT) | |
2062 | return nid; | |
2063 | ||
2064 | /* | |
2065 | * On a system with glueless mesh NUMA topology, group_weight | |
2066 | * scores nodes according to the number of NUMA hinting faults on | |
2067 | * both the node itself, and on nearby nodes. | |
2068 | */ | |
2069 | if (sched_numa_topology_type == NUMA_GLUELESS_MESH) { | |
2070 | unsigned long score, max_score = 0; | |
2071 | int node, max_node = nid; | |
2072 | ||
2073 | dist = sched_max_numa_distance; | |
2074 | ||
2075 | for_each_online_node(node) { | |
2076 | score = group_weight(p, node, dist); | |
2077 | if (score > max_score) { | |
2078 | max_score = score; | |
2079 | max_node = node; | |
2080 | } | |
2081 | } | |
2082 | return max_node; | |
2083 | } | |
2084 | ||
2085 | /* | |
2086 | * Finding the preferred nid in a system with NUMA backplane | |
2087 | * interconnect topology is more involved. The goal is to locate | |
2088 | * tasks from numa_groups near each other in the system, and | |
2089 | * untangle workloads from different sides of the system. This requires | |
2090 | * searching down the hierarchy of node groups, recursively searching | |
2091 | * inside the highest scoring group of nodes. The nodemask tricks | |
2092 | * keep the complexity of the search down. | |
2093 | */ | |
2094 | nodes = node_online_map; | |
2095 | for (dist = sched_max_numa_distance; dist > LOCAL_DISTANCE; dist--) { | |
2096 | unsigned long max_faults = 0; | |
81907478 | 2097 | nodemask_t max_group = NODE_MASK_NONE; |
54009416 RR |
2098 | int a, b; |
2099 | ||
2100 | /* Are there nodes at this distance from each other? */ | |
2101 | if (!find_numa_distance(dist)) | |
2102 | continue; | |
2103 | ||
2104 | for_each_node_mask(a, nodes) { | |
2105 | unsigned long faults = 0; | |
2106 | nodemask_t this_group; | |
2107 | nodes_clear(this_group); | |
2108 | ||
2109 | /* Sum group's NUMA faults; includes a==b case. */ | |
2110 | for_each_node_mask(b, nodes) { | |
2111 | if (node_distance(a, b) < dist) { | |
2112 | faults += group_faults(p, b); | |
2113 | node_set(b, this_group); | |
2114 | node_clear(b, nodes); | |
2115 | } | |
2116 | } | |
2117 | ||
2118 | /* Remember the top group. */ | |
2119 | if (faults > max_faults) { | |
2120 | max_faults = faults; | |
2121 | max_group = this_group; | |
2122 | /* | |
2123 | * subtle: at the smallest distance there is | |
2124 | * just one node left in each "group", the | |
2125 | * winner is the preferred nid. | |
2126 | */ | |
2127 | nid = a; | |
2128 | } | |
2129 | } | |
2130 | /* Next round, evaluate the nodes within max_group. */ | |
890a5409 JB |
2131 | if (!max_faults) |
2132 | break; | |
54009416 RR |
2133 | nodes = max_group; |
2134 | } | |
2135 | return nid; | |
2136 | } | |
2137 | ||
cbee9f88 PZ |
2138 | static void task_numa_placement(struct task_struct *p) |
2139 | { | |
83e1d2cd MG |
2140 | int seq, nid, max_nid = -1, max_group_nid = -1; |
2141 | unsigned long max_faults = 0, max_group_faults = 0; | |
04bb2f94 | 2142 | unsigned long fault_types[2] = { 0, 0 }; |
7e2703e6 RR |
2143 | unsigned long total_faults; |
2144 | u64 runtime, period; | |
7dbd13ed | 2145 | spinlock_t *group_lock = NULL; |
cbee9f88 | 2146 | |
7e5a2c17 JL |
2147 | /* |
2148 | * The p->mm->numa_scan_seq field gets updated without | |
2149 | * exclusive access. Use READ_ONCE() here to ensure | |
2150 | * that the field is read in a single access: | |
2151 | */ | |
316c1608 | 2152 | seq = READ_ONCE(p->mm->numa_scan_seq); |
cbee9f88 PZ |
2153 | if (p->numa_scan_seq == seq) |
2154 | return; | |
2155 | p->numa_scan_seq = seq; | |
598f0ec0 | 2156 | p->numa_scan_period_max = task_scan_max(p); |
cbee9f88 | 2157 | |
7e2703e6 RR |
2158 | total_faults = p->numa_faults_locality[0] + |
2159 | p->numa_faults_locality[1]; | |
2160 | runtime = numa_get_avg_runtime(p, &period); | |
2161 | ||
7dbd13ed MG |
2162 | /* If the task is part of a group prevent parallel updates to group stats */ |
2163 | if (p->numa_group) { | |
2164 | group_lock = &p->numa_group->lock; | |
60e69eed | 2165 | spin_lock_irq(group_lock); |
7dbd13ed MG |
2166 | } |
2167 | ||
688b7585 MG |
2168 | /* Find the node with the highest number of faults */ |
2169 | for_each_online_node(nid) { | |
44dba3d5 IM |
2170 | /* Keep track of the offsets in numa_faults array */ |
2171 | int mem_idx, membuf_idx, cpu_idx, cpubuf_idx; | |
83e1d2cd | 2172 | unsigned long faults = 0, group_faults = 0; |
44dba3d5 | 2173 | int priv; |
745d6147 | 2174 | |
be1e4e76 | 2175 | for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) { |
7e2703e6 | 2176 | long diff, f_diff, f_weight; |
8c8a743c | 2177 | |
44dba3d5 IM |
2178 | mem_idx = task_faults_idx(NUMA_MEM, nid, priv); |
2179 | membuf_idx = task_faults_idx(NUMA_MEMBUF, nid, priv); | |
2180 | cpu_idx = task_faults_idx(NUMA_CPU, nid, priv); | |
2181 | cpubuf_idx = task_faults_idx(NUMA_CPUBUF, nid, priv); | |
745d6147 | 2182 | |
ac8e895b | 2183 | /* Decay existing window, copy faults since last scan */ |
44dba3d5 IM |
2184 | diff = p->numa_faults[membuf_idx] - p->numa_faults[mem_idx] / 2; |
2185 | fault_types[priv] += p->numa_faults[membuf_idx]; | |
2186 | p->numa_faults[membuf_idx] = 0; | |
fb13c7ee | 2187 | |
7e2703e6 RR |
2188 | /* |
2189 | * Normalize the faults_from, so all tasks in a group | |
2190 | * count according to CPU use, instead of by the raw | |
2191 | * number of faults. Tasks with little runtime have | |
2192 | * little over-all impact on throughput, and thus their | |
2193 | * faults are less important. | |
2194 | */ | |
2195 | f_weight = div64_u64(runtime << 16, period + 1); | |
44dba3d5 | 2196 | f_weight = (f_weight * p->numa_faults[cpubuf_idx]) / |
7e2703e6 | 2197 | (total_faults + 1); |
44dba3d5 IM |
2198 | f_diff = f_weight - p->numa_faults[cpu_idx] / 2; |
2199 | p->numa_faults[cpubuf_idx] = 0; | |
50ec8a40 | 2200 | |
44dba3d5 IM |
2201 | p->numa_faults[mem_idx] += diff; |
2202 | p->numa_faults[cpu_idx] += f_diff; | |
2203 | faults += p->numa_faults[mem_idx]; | |
83e1d2cd | 2204 | p->total_numa_faults += diff; |
8c8a743c | 2205 | if (p->numa_group) { |
44dba3d5 IM |
2206 | /* |
2207 | * safe because we can only change our own group | |
2208 | * | |
2209 | * mem_idx represents the offset for a given | |
2210 | * nid and priv in a specific region because it | |
2211 | * is at the beginning of the numa_faults array. | |
2212 | */ | |
2213 | p->numa_group->faults[mem_idx] += diff; | |
2214 | p->numa_group->faults_cpu[mem_idx] += f_diff; | |
989348b5 | 2215 | p->numa_group->total_faults += diff; |
44dba3d5 | 2216 | group_faults += p->numa_group->faults[mem_idx]; |
8c8a743c | 2217 | } |
ac8e895b MG |
2218 | } |
2219 | ||
688b7585 MG |
2220 | if (faults > max_faults) { |
2221 | max_faults = faults; | |
2222 | max_nid = nid; | |
2223 | } | |
83e1d2cd MG |
2224 | |
2225 | if (group_faults > max_group_faults) { | |
2226 | max_group_faults = group_faults; | |
2227 | max_group_nid = nid; | |
2228 | } | |
2229 | } | |
2230 | ||
04bb2f94 RR |
2231 | update_task_scan_period(p, fault_types[0], fault_types[1]); |
2232 | ||
7dbd13ed | 2233 | if (p->numa_group) { |
4142c3eb | 2234 | numa_group_count_active_nodes(p->numa_group); |
60e69eed | 2235 | spin_unlock_irq(group_lock); |
54009416 | 2236 | max_nid = preferred_group_nid(p, max_group_nid); |
688b7585 MG |
2237 | } |
2238 | ||
bb97fc31 RR |
2239 | if (max_faults) { |
2240 | /* Set the new preferred node */ | |
2241 | if (max_nid != p->numa_preferred_nid) | |
2242 | sched_setnuma(p, max_nid); | |
2243 | ||
2244 | if (task_node(p) != p->numa_preferred_nid) | |
2245 | numa_migrate_preferred(p); | |
3a7053b3 | 2246 | } |
cbee9f88 PZ |
2247 | } |
2248 | ||
8c8a743c PZ |
2249 | static inline int get_numa_group(struct numa_group *grp) |
2250 | { | |
2251 | return atomic_inc_not_zero(&grp->refcount); | |
2252 | } | |
2253 | ||
2254 | static inline void put_numa_group(struct numa_group *grp) | |
2255 | { | |
2256 | if (atomic_dec_and_test(&grp->refcount)) | |
2257 | kfree_rcu(grp, rcu); | |
2258 | } | |
2259 | ||
3e6a9418 MG |
2260 | static void task_numa_group(struct task_struct *p, int cpupid, int flags, |
2261 | int *priv) | |
8c8a743c PZ |
2262 | { |
2263 | struct numa_group *grp, *my_grp; | |
2264 | struct task_struct *tsk; | |
2265 | bool join = false; | |
2266 | int cpu = cpupid_to_cpu(cpupid); | |
2267 | int i; | |
2268 | ||
2269 | if (unlikely(!p->numa_group)) { | |
2270 | unsigned int size = sizeof(struct numa_group) + | |
50ec8a40 | 2271 | 4*nr_node_ids*sizeof(unsigned long); |
8c8a743c PZ |
2272 | |
2273 | grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); | |
2274 | if (!grp) | |
2275 | return; | |
2276 | ||
2277 | atomic_set(&grp->refcount, 1); | |
4142c3eb RR |
2278 | grp->active_nodes = 1; |
2279 | grp->max_faults_cpu = 0; | |
8c8a743c | 2280 | spin_lock_init(&grp->lock); |
e29cf08b | 2281 | grp->gid = p->pid; |
50ec8a40 | 2282 | /* Second half of the array tracks nids where faults happen */ |
be1e4e76 RR |
2283 | grp->faults_cpu = grp->faults + NR_NUMA_HINT_FAULT_TYPES * |
2284 | nr_node_ids; | |
8c8a743c | 2285 | |
be1e4e76 | 2286 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) |
44dba3d5 | 2287 | grp->faults[i] = p->numa_faults[i]; |
8c8a743c | 2288 | |
989348b5 | 2289 | grp->total_faults = p->total_numa_faults; |
83e1d2cd | 2290 | |
8c8a743c PZ |
2291 | grp->nr_tasks++; |
2292 | rcu_assign_pointer(p->numa_group, grp); | |
2293 | } | |
2294 | ||
2295 | rcu_read_lock(); | |
316c1608 | 2296 | tsk = READ_ONCE(cpu_rq(cpu)->curr); |
8c8a743c PZ |
2297 | |
2298 | if (!cpupid_match_pid(tsk, cpupid)) | |
3354781a | 2299 | goto no_join; |
8c8a743c PZ |
2300 | |
2301 | grp = rcu_dereference(tsk->numa_group); | |
2302 | if (!grp) | |
3354781a | 2303 | goto no_join; |
8c8a743c PZ |
2304 | |
2305 | my_grp = p->numa_group; | |
2306 | if (grp == my_grp) | |
3354781a | 2307 | goto no_join; |
8c8a743c PZ |
2308 | |
2309 | /* | |
2310 | * Only join the other group if its bigger; if we're the bigger group, | |
2311 | * the other task will join us. | |
2312 | */ | |
2313 | if (my_grp->nr_tasks > grp->nr_tasks) | |
3354781a | 2314 | goto no_join; |
8c8a743c PZ |
2315 | |
2316 | /* | |
2317 | * Tie-break on the grp address. | |
2318 | */ | |
2319 | if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp) | |
3354781a | 2320 | goto no_join; |
8c8a743c | 2321 | |
dabe1d99 RR |
2322 | /* Always join threads in the same process. */ |
2323 | if (tsk->mm == current->mm) | |
2324 | join = true; | |
2325 | ||
2326 | /* Simple filter to avoid false positives due to PID collisions */ | |
2327 | if (flags & TNF_SHARED) | |
2328 | join = true; | |
8c8a743c | 2329 | |
3e6a9418 MG |
2330 | /* Update priv based on whether false sharing was detected */ |
2331 | *priv = !join; | |
2332 | ||
dabe1d99 | 2333 | if (join && !get_numa_group(grp)) |
3354781a | 2334 | goto no_join; |
8c8a743c | 2335 | |
8c8a743c PZ |
2336 | rcu_read_unlock(); |
2337 | ||
2338 | if (!join) | |
2339 | return; | |
2340 | ||
60e69eed MG |
2341 | BUG_ON(irqs_disabled()); |
2342 | double_lock_irq(&my_grp->lock, &grp->lock); | |
989348b5 | 2343 | |
be1e4e76 | 2344 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) { |
44dba3d5 IM |
2345 | my_grp->faults[i] -= p->numa_faults[i]; |
2346 | grp->faults[i] += p->numa_faults[i]; | |
8c8a743c | 2347 | } |
989348b5 MG |
2348 | my_grp->total_faults -= p->total_numa_faults; |
2349 | grp->total_faults += p->total_numa_faults; | |
8c8a743c | 2350 | |
8c8a743c PZ |
2351 | my_grp->nr_tasks--; |
2352 | grp->nr_tasks++; | |
2353 | ||
2354 | spin_unlock(&my_grp->lock); | |
60e69eed | 2355 | spin_unlock_irq(&grp->lock); |
8c8a743c PZ |
2356 | |
2357 | rcu_assign_pointer(p->numa_group, grp); | |
2358 | ||
2359 | put_numa_group(my_grp); | |
3354781a PZ |
2360 | return; |
2361 | ||
2362 | no_join: | |
2363 | rcu_read_unlock(); | |
2364 | return; | |
8c8a743c PZ |
2365 | } |
2366 | ||
30197fa5 JH |
2367 | /* |
2368 | * Get rid of NUMA staticstics associated with a task (either current or dead). | |
2369 | * If @final is set, the task is dead and has reached refcount zero, so we can | |
2370 | * safely free all relevant data structures. Otherwise, there might be | |
2371 | * concurrent reads from places like load balancing and procfs, and we should | |
2372 | * reset the data back to default state without freeing ->numa_faults. | |
2373 | */ | |
2374 | void task_numa_free(struct task_struct *p, bool final) | |
8c8a743c PZ |
2375 | { |
2376 | struct numa_group *grp = p->numa_group; | |
30197fa5 | 2377 | unsigned long *numa_faults = p->numa_faults; |
e9dd685c SR |
2378 | unsigned long flags; |
2379 | int i; | |
8c8a743c | 2380 | |
30197fa5 JH |
2381 | if (!numa_faults) |
2382 | return; | |
2383 | ||
8c8a743c | 2384 | if (grp) { |
e9dd685c | 2385 | spin_lock_irqsave(&grp->lock, flags); |
be1e4e76 | 2386 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) |
44dba3d5 | 2387 | grp->faults[i] -= p->numa_faults[i]; |
989348b5 | 2388 | grp->total_faults -= p->total_numa_faults; |
83e1d2cd | 2389 | |
8c8a743c | 2390 | grp->nr_tasks--; |
e9dd685c | 2391 | spin_unlock_irqrestore(&grp->lock, flags); |
35b123e2 | 2392 | RCU_INIT_POINTER(p->numa_group, NULL); |
8c8a743c PZ |
2393 | put_numa_group(grp); |
2394 | } | |
2395 | ||
30197fa5 JH |
2396 | if (final) { |
2397 | p->numa_faults = NULL; | |
2398 | kfree(numa_faults); | |
2399 | } else { | |
2400 | p->total_numa_faults = 0; | |
2401 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) | |
2402 | numa_faults[i] = 0; | |
2403 | } | |
8c8a743c PZ |
2404 | } |
2405 | ||
cbee9f88 PZ |
2406 | /* |
2407 | * Got a PROT_NONE fault for a page on @node. | |
2408 | */ | |
58b46da3 | 2409 | void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags) |
cbee9f88 PZ |
2410 | { |
2411 | struct task_struct *p = current; | |
6688cc05 | 2412 | bool migrated = flags & TNF_MIGRATED; |
58b46da3 | 2413 | int cpu_node = task_node(current); |
792568ec | 2414 | int local = !!(flags & TNF_FAULT_LOCAL); |
4142c3eb | 2415 | struct numa_group *ng; |
ac8e895b | 2416 | int priv; |
cbee9f88 | 2417 | |
2a595721 | 2418 | if (!static_branch_likely(&sched_numa_balancing)) |
1a687c2e MG |
2419 | return; |
2420 | ||
9ff1d9ff MG |
2421 | /* for example, ksmd faulting in a user's mm */ |
2422 | if (!p->mm) | |
2423 | return; | |
2424 | ||
f809ca9a | 2425 | /* Allocate buffer to track faults on a per-node basis */ |
44dba3d5 IM |
2426 | if (unlikely(!p->numa_faults)) { |
2427 | int size = sizeof(*p->numa_faults) * | |
be1e4e76 | 2428 | NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids; |
f809ca9a | 2429 | |
44dba3d5 IM |
2430 | p->numa_faults = kzalloc(size, GFP_KERNEL|__GFP_NOWARN); |
2431 | if (!p->numa_faults) | |
f809ca9a | 2432 | return; |
745d6147 | 2433 | |
83e1d2cd | 2434 | p->total_numa_faults = 0; |
04bb2f94 | 2435 | memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); |
f809ca9a | 2436 | } |
cbee9f88 | 2437 | |
8c8a743c PZ |
2438 | /* |
2439 | * First accesses are treated as private, otherwise consider accesses | |
2440 | * to be private if the accessing pid has not changed | |
2441 | */ | |
2442 | if (unlikely(last_cpupid == (-1 & LAST_CPUPID_MASK))) { | |
2443 | priv = 1; | |
2444 | } else { | |
2445 | priv = cpupid_match_pid(p, last_cpupid); | |
6688cc05 | 2446 | if (!priv && !(flags & TNF_NO_GROUP)) |
3e6a9418 | 2447 | task_numa_group(p, last_cpupid, flags, &priv); |
8c8a743c PZ |
2448 | } |
2449 | ||
792568ec RR |
2450 | /* |
2451 | * If a workload spans multiple NUMA nodes, a shared fault that | |
2452 | * occurs wholly within the set of nodes that the workload is | |
2453 | * actively using should be counted as local. This allows the | |
2454 | * scan rate to slow down when a workload has settled down. | |
2455 | */ | |
4142c3eb RR |
2456 | ng = p->numa_group; |
2457 | if (!priv && !local && ng && ng->active_nodes > 1 && | |
2458 | numa_is_active_node(cpu_node, ng) && | |
2459 | numa_is_active_node(mem_node, ng)) | |
792568ec RR |
2460 | local = 1; |
2461 | ||
cbee9f88 | 2462 | task_numa_placement(p); |
f809ca9a | 2463 | |
2739d3ee RR |
2464 | /* |
2465 | * Retry task to preferred node migration periodically, in case it | |
2466 | * case it previously failed, or the scheduler moved us. | |
2467 | */ | |
2468 | if (time_after(jiffies, p->numa_migrate_retry)) | |
6b9a7460 MG |
2469 | numa_migrate_preferred(p); |
2470 | ||
b32e86b4 IM |
2471 | if (migrated) |
2472 | p->numa_pages_migrated += pages; | |
074c2381 MG |
2473 | if (flags & TNF_MIGRATE_FAIL) |
2474 | p->numa_faults_locality[2] += pages; | |
b32e86b4 | 2475 | |
44dba3d5 IM |
2476 | p->numa_faults[task_faults_idx(NUMA_MEMBUF, mem_node, priv)] += pages; |
2477 | p->numa_faults[task_faults_idx(NUMA_CPUBUF, cpu_node, priv)] += pages; | |
792568ec | 2478 | p->numa_faults_locality[local] += pages; |
cbee9f88 PZ |
2479 | } |
2480 | ||
6e5fb223 PZ |
2481 | static void reset_ptenuma_scan(struct task_struct *p) |
2482 | { | |
7e5a2c17 JL |
2483 | /* |
2484 | * We only did a read acquisition of the mmap sem, so | |
2485 | * p->mm->numa_scan_seq is written to without exclusive access | |
2486 | * and the update is not guaranteed to be atomic. That's not | |
2487 | * much of an issue though, since this is just used for | |
2488 | * statistical sampling. Use READ_ONCE/WRITE_ONCE, which are not | |
2489 | * expensive, to avoid any form of compiler optimizations: | |
2490 | */ | |
316c1608 | 2491 | WRITE_ONCE(p->mm->numa_scan_seq, READ_ONCE(p->mm->numa_scan_seq) + 1); |
6e5fb223 PZ |
2492 | p->mm->numa_scan_offset = 0; |
2493 | } | |
2494 | ||
cbee9f88 PZ |
2495 | /* |
2496 | * The expensive part of numa migration is done from task_work context. | |
2497 | * Triggered from task_tick_numa(). | |
2498 | */ | |
2499 | void task_numa_work(struct callback_head *work) | |
2500 | { | |
2501 | unsigned long migrate, next_scan, now = jiffies; | |
2502 | struct task_struct *p = current; | |
2503 | struct mm_struct *mm = p->mm; | |
51170840 | 2504 | u64 runtime = p->se.sum_exec_runtime; |
6e5fb223 | 2505 | struct vm_area_struct *vma; |
9f40604c | 2506 | unsigned long start, end; |
598f0ec0 | 2507 | unsigned long nr_pte_updates = 0; |
4620f8c1 | 2508 | long pages, virtpages; |
cbee9f88 | 2509 | |
9148a3a1 | 2510 | SCHED_WARN_ON(p != container_of(work, struct task_struct, numa_work)); |
cbee9f88 PZ |
2511 | |
2512 | work->next = work; /* protect against double add */ | |
2513 | /* | |
2514 | * Who cares about NUMA placement when they're dying. | |
2515 | * | |
2516 | * NOTE: make sure not to dereference p->mm before this check, | |
2517 | * exit_task_work() happens _after_ exit_mm() so we could be called | |
2518 | * without p->mm even though we still had it when we enqueued this | |
2519 | * work. | |
2520 | */ | |
2521 | if (p->flags & PF_EXITING) | |
2522 | return; | |
2523 | ||
930aa174 | 2524 | if (!mm->numa_next_scan) { |
7e8d16b6 MG |
2525 | mm->numa_next_scan = now + |
2526 | msecs_to_jiffies(sysctl_numa_balancing_scan_delay); | |
b8593bfd MG |
2527 | } |
2528 | ||
cbee9f88 PZ |
2529 | /* |
2530 | * Enforce maximal scan/migration frequency.. | |
2531 | */ | |
2532 | migrate = mm->numa_next_scan; | |
2533 | if (time_before(now, migrate)) | |
2534 | return; | |
2535 | ||
598f0ec0 MG |
2536 | if (p->numa_scan_period == 0) { |
2537 | p->numa_scan_period_max = task_scan_max(p); | |
b5dd77c8 | 2538 | p->numa_scan_period = task_scan_start(p); |
598f0ec0 | 2539 | } |
cbee9f88 | 2540 | |
fb003b80 | 2541 | next_scan = now + msecs_to_jiffies(p->numa_scan_period); |
cbee9f88 PZ |
2542 | if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate) |
2543 | return; | |
2544 | ||
19a78d11 PZ |
2545 | /* |
2546 | * Delay this task enough that another task of this mm will likely win | |
2547 | * the next time around. | |
2548 | */ | |
2549 | p->node_stamp += 2 * TICK_NSEC; | |
2550 | ||
9f40604c MG |
2551 | start = mm->numa_scan_offset; |
2552 | pages = sysctl_numa_balancing_scan_size; | |
2553 | pages <<= 20 - PAGE_SHIFT; /* MB in pages */ | |
4620f8c1 | 2554 | virtpages = pages * 8; /* Scan up to this much virtual space */ |
9f40604c MG |
2555 | if (!pages) |
2556 | return; | |
cbee9f88 | 2557 | |
4620f8c1 | 2558 | |
8655d549 VB |
2559 | if (!down_read_trylock(&mm->mmap_sem)) |
2560 | return; | |
9f40604c | 2561 | vma = find_vma(mm, start); |
6e5fb223 PZ |
2562 | if (!vma) { |
2563 | reset_ptenuma_scan(p); | |
9f40604c | 2564 | start = 0; |
6e5fb223 PZ |
2565 | vma = mm->mmap; |
2566 | } | |
9f40604c | 2567 | for (; vma; vma = vma->vm_next) { |
6b79c57b | 2568 | if (!vma_migratable(vma) || !vma_policy_mof(vma) || |
8e76d4ee | 2569 | is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_MIXEDMAP)) { |
6e5fb223 | 2570 | continue; |
6b79c57b | 2571 | } |
6e5fb223 | 2572 | |
4591ce4f MG |
2573 | /* |
2574 | * Shared library pages mapped by multiple processes are not | |
2575 | * migrated as it is expected they are cache replicated. Avoid | |
2576 | * hinting faults in read-only file-backed mappings or the vdso | |
2577 | * as migrating the pages will be of marginal benefit. | |
2578 | */ | |
2579 | if (!vma->vm_mm || | |
2580 | (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ))) | |
2581 | continue; | |
2582 | ||
3c67f474 MG |
2583 | /* |
2584 | * Skip inaccessible VMAs to avoid any confusion between | |
2585 | * PROT_NONE and NUMA hinting ptes | |
2586 | */ | |
2587 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) | |
2588 | continue; | |
4591ce4f | 2589 | |
9f40604c MG |
2590 | do { |
2591 | start = max(start, vma->vm_start); | |
2592 | end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE); | |
2593 | end = min(end, vma->vm_end); | |
4620f8c1 | 2594 | nr_pte_updates = change_prot_numa(vma, start, end); |
598f0ec0 MG |
2595 | |
2596 | /* | |
4620f8c1 RR |
2597 | * Try to scan sysctl_numa_balancing_size worth of |
2598 | * hpages that have at least one present PTE that | |
2599 | * is not already pte-numa. If the VMA contains | |
2600 | * areas that are unused or already full of prot_numa | |
2601 | * PTEs, scan up to virtpages, to skip through those | |
2602 | * areas faster. | |
598f0ec0 MG |
2603 | */ |
2604 | if (nr_pte_updates) | |
2605 | pages -= (end - start) >> PAGE_SHIFT; | |
4620f8c1 | 2606 | virtpages -= (end - start) >> PAGE_SHIFT; |
6e5fb223 | 2607 | |
9f40604c | 2608 | start = end; |
4620f8c1 | 2609 | if (pages <= 0 || virtpages <= 0) |
9f40604c | 2610 | goto out; |
3cf1962c RR |
2611 | |
2612 | cond_resched(); | |
9f40604c | 2613 | } while (end != vma->vm_end); |
cbee9f88 | 2614 | } |
6e5fb223 | 2615 | |
9f40604c | 2616 | out: |
6e5fb223 | 2617 | /* |
c69307d5 PZ |
2618 | * It is possible to reach the end of the VMA list but the last few |
2619 | * VMAs are not guaranteed to the vma_migratable. If they are not, we | |
2620 | * would find the !migratable VMA on the next scan but not reset the | |
2621 | * scanner to the start so check it now. | |
6e5fb223 PZ |
2622 | */ |
2623 | if (vma) | |
9f40604c | 2624 | mm->numa_scan_offset = start; |
6e5fb223 PZ |
2625 | else |
2626 | reset_ptenuma_scan(p); | |
2627 | up_read(&mm->mmap_sem); | |
51170840 RR |
2628 | |
2629 | /* | |
2630 | * Make sure tasks use at least 32x as much time to run other code | |
2631 | * than they used here, to limit NUMA PTE scanning overhead to 3% max. | |
2632 | * Usually update_task_scan_period slows down scanning enough; on an | |
2633 | * overloaded system we need to limit overhead on a per task basis. | |
2634 | */ | |
2635 | if (unlikely(p->se.sum_exec_runtime != runtime)) { | |
2636 | u64 diff = p->se.sum_exec_runtime - runtime; | |
2637 | p->node_stamp += 32 * diff; | |
2638 | } | |
cbee9f88 PZ |
2639 | } |
2640 | ||
2641 | /* | |
2642 | * Drive the periodic memory faults.. | |
2643 | */ | |
2644 | void task_tick_numa(struct rq *rq, struct task_struct *curr) | |
2645 | { | |
2646 | struct callback_head *work = &curr->numa_work; | |
2647 | u64 period, now; | |
2648 | ||
2649 | /* | |
2650 | * We don't care about NUMA placement if we don't have memory. | |
2651 | */ | |
2652 | if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work) | |
2653 | return; | |
2654 | ||
2655 | /* | |
2656 | * Using runtime rather than walltime has the dual advantage that | |
2657 | * we (mostly) drive the selection from busy threads and that the | |
2658 | * task needs to have done some actual work before we bother with | |
2659 | * NUMA placement. | |
2660 | */ | |
2661 | now = curr->se.sum_exec_runtime; | |
2662 | period = (u64)curr->numa_scan_period * NSEC_PER_MSEC; | |
2663 | ||
25b3e5a3 | 2664 | if (now > curr->node_stamp + period) { |
4b96a29b | 2665 | if (!curr->node_stamp) |
b5dd77c8 | 2666 | curr->numa_scan_period = task_scan_start(curr); |
19a78d11 | 2667 | curr->node_stamp += period; |
cbee9f88 PZ |
2668 | |
2669 | if (!time_before(jiffies, curr->mm->numa_next_scan)) { | |
2670 | init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */ | |
2671 | task_work_add(curr, work, true); | |
2672 | } | |
2673 | } | |
2674 | } | |
3fed382b | 2675 | |
cbee9f88 PZ |
2676 | #else |
2677 | static void task_tick_numa(struct rq *rq, struct task_struct *curr) | |
2678 | { | |
2679 | } | |
0ec8aa00 PZ |
2680 | |
2681 | static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p) | |
2682 | { | |
2683 | } | |
2684 | ||
2685 | static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p) | |
2686 | { | |
2687 | } | |
3fed382b | 2688 | |
cbee9f88 PZ |
2689 | #endif /* CONFIG_NUMA_BALANCING */ |
2690 | ||
30cfdcfc DA |
2691 | static void |
2692 | account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2693 | { | |
2694 | update_load_add(&cfs_rq->load, se->load.weight); | |
c09595f6 | 2695 | if (!parent_entity(se)) |
029632fb | 2696 | update_load_add(&rq_of(cfs_rq)->load, se->load.weight); |
367456c7 | 2697 | #ifdef CONFIG_SMP |
0ec8aa00 PZ |
2698 | if (entity_is_task(se)) { |
2699 | struct rq *rq = rq_of(cfs_rq); | |
2700 | ||
2701 | account_numa_enqueue(rq, task_of(se)); | |
2702 | list_add(&se->group_node, &rq->cfs_tasks); | |
2703 | } | |
367456c7 | 2704 | #endif |
30cfdcfc | 2705 | cfs_rq->nr_running++; |
30cfdcfc DA |
2706 | } |
2707 | ||
2708 | static void | |
2709 | account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2710 | { | |
2711 | update_load_sub(&cfs_rq->load, se->load.weight); | |
c09595f6 | 2712 | if (!parent_entity(se)) |
029632fb | 2713 | update_load_sub(&rq_of(cfs_rq)->load, se->load.weight); |
bfdb198c | 2714 | #ifdef CONFIG_SMP |
0ec8aa00 PZ |
2715 | if (entity_is_task(se)) { |
2716 | account_numa_dequeue(rq_of(cfs_rq), task_of(se)); | |
b87f1724 | 2717 | list_del_init(&se->group_node); |
0ec8aa00 | 2718 | } |
bfdb198c | 2719 | #endif |
30cfdcfc | 2720 | cfs_rq->nr_running--; |
30cfdcfc DA |
2721 | } |
2722 | ||
8d5b9025 PZ |
2723 | /* |
2724 | * Signed add and clamp on underflow. | |
2725 | * | |
2726 | * Explicitly do a load-store to ensure the intermediate value never hits | |
2727 | * memory. This allows lockless observations without ever seeing the negative | |
2728 | * values. | |
2729 | */ | |
2730 | #define add_positive(_ptr, _val) do { \ | |
2731 | typeof(_ptr) ptr = (_ptr); \ | |
2732 | typeof(_val) val = (_val); \ | |
2733 | typeof(*ptr) res, var = READ_ONCE(*ptr); \ | |
2734 | \ | |
2735 | res = var + val; \ | |
2736 | \ | |
2737 | if (val < 0 && res > var) \ | |
2738 | res = 0; \ | |
2739 | \ | |
2740 | WRITE_ONCE(*ptr, res); \ | |
2741 | } while (0) | |
2742 | ||
2743 | /* | |
2744 | * Unsigned subtract and clamp on underflow. | |
2745 | * | |
2746 | * Explicitly do a load-store to ensure the intermediate value never hits | |
2747 | * memory. This allows lockless observations without ever seeing the negative | |
2748 | * values. | |
2749 | */ | |
2750 | #define sub_positive(_ptr, _val) do { \ | |
2751 | typeof(_ptr) ptr = (_ptr); \ | |
2752 | typeof(*ptr) val = (_val); \ | |
2753 | typeof(*ptr) res, var = READ_ONCE(*ptr); \ | |
2754 | res = var - val; \ | |
2755 | if (res > var) \ | |
2756 | res = 0; \ | |
2757 | WRITE_ONCE(*ptr, res); \ | |
2758 | } while (0) | |
2759 | ||
834ef3c9 PB |
2760 | /* |
2761 | * Remove and clamp on negative, from a local variable. | |
2762 | * | |
2763 | * A variant of sub_positive(), which does not use explicit load-store | |
2764 | * and is thus optimized for local variable updates. | |
2765 | */ | |
2766 | #define lsub_positive(_ptr, _val) do { \ | |
2767 | typeof(_ptr) ptr = (_ptr); \ | |
2768 | *ptr -= min_t(typeof(*ptr), *ptr, _val); \ | |
2769 | } while (0) | |
2770 | ||
8d5b9025 PZ |
2771 | #ifdef CONFIG_SMP |
2772 | /* | |
1ea6c46a | 2773 | * XXX we want to get rid of these helpers and use the full load resolution. |
8d5b9025 PZ |
2774 | */ |
2775 | static inline long se_weight(struct sched_entity *se) | |
2776 | { | |
2777 | return scale_load_down(se->load.weight); | |
2778 | } | |
2779 | ||
1ea6c46a PZ |
2780 | static inline long se_runnable(struct sched_entity *se) |
2781 | { | |
2782 | return scale_load_down(se->runnable_weight); | |
2783 | } | |
2784 | ||
8d5b9025 PZ |
2785 | static inline void |
2786 | enqueue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2787 | { | |
1ea6c46a PZ |
2788 | cfs_rq->runnable_weight += se->runnable_weight; |
2789 | ||
2790 | cfs_rq->avg.runnable_load_avg += se->avg.runnable_load_avg; | |
2791 | cfs_rq->avg.runnable_load_sum += se_runnable(se) * se->avg.runnable_load_sum; | |
8d5b9025 PZ |
2792 | } |
2793 | ||
2794 | static inline void | |
2795 | dequeue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2796 | { | |
1ea6c46a PZ |
2797 | cfs_rq->runnable_weight -= se->runnable_weight; |
2798 | ||
2799 | sub_positive(&cfs_rq->avg.runnable_load_avg, se->avg.runnable_load_avg); | |
2800 | sub_positive(&cfs_rq->avg.runnable_load_sum, | |
2801 | se_runnable(se) * se->avg.runnable_load_sum); | |
8d5b9025 PZ |
2802 | } |
2803 | ||
2804 | static inline void | |
2805 | enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2806 | { | |
2807 | cfs_rq->avg.load_avg += se->avg.load_avg; | |
2808 | cfs_rq->avg.load_sum += se_weight(se) * se->avg.load_sum; | |
2809 | } | |
2810 | ||
2811 | static inline void | |
2812 | dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2813 | { | |
2814 | sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg); | |
2815 | sub_positive(&cfs_rq->avg.load_sum, se_weight(se) * se->avg.load_sum); | |
2816 | } | |
2817 | #else | |
2818 | static inline void | |
2819 | enqueue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { } | |
2820 | static inline void | |
2821 | dequeue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { } | |
2822 | static inline void | |
2823 | enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { } | |
2824 | static inline void | |
2825 | dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { } | |
2826 | #endif | |
2827 | ||
9059393e | 2828 | static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, |
1ea6c46a | 2829 | unsigned long weight, unsigned long runnable) |
9059393e VG |
2830 | { |
2831 | if (se->on_rq) { | |
2832 | /* commit outstanding execution time */ | |
2833 | if (cfs_rq->curr == se) | |
2834 | update_curr(cfs_rq); | |
2835 | account_entity_dequeue(cfs_rq, se); | |
2836 | dequeue_runnable_load_avg(cfs_rq, se); | |
2837 | } | |
2838 | dequeue_load_avg(cfs_rq, se); | |
2839 | ||
1ea6c46a | 2840 | se->runnable_weight = runnable; |
9059393e VG |
2841 | update_load_set(&se->load, weight); |
2842 | ||
2843 | #ifdef CONFIG_SMP | |
1ea6c46a PZ |
2844 | do { |
2845 | u32 divider = LOAD_AVG_MAX - 1024 + se->avg.period_contrib; | |
2846 | ||
2847 | se->avg.load_avg = div_u64(se_weight(se) * se->avg.load_sum, divider); | |
2848 | se->avg.runnable_load_avg = | |
2849 | div_u64(se_runnable(se) * se->avg.runnable_load_sum, divider); | |
2850 | } while (0); | |
9059393e VG |
2851 | #endif |
2852 | ||
2853 | enqueue_load_avg(cfs_rq, se); | |
2854 | if (se->on_rq) { | |
2855 | account_entity_enqueue(cfs_rq, se); | |
2856 | enqueue_runnable_load_avg(cfs_rq, se); | |
2857 | } | |
2858 | } | |
2859 | ||
2860 | void reweight_task(struct task_struct *p, int prio) | |
2861 | { | |
2862 | struct sched_entity *se = &p->se; | |
2863 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
2864 | struct load_weight *load = &se->load; | |
2865 | unsigned long weight = scale_load(sched_prio_to_weight[prio]); | |
2866 | ||
1ea6c46a | 2867 | reweight_entity(cfs_rq, se, weight, weight); |
9059393e VG |
2868 | load->inv_weight = sched_prio_to_wmult[prio]; |
2869 | } | |
2870 | ||
3ff6dcac YZ |
2871 | #ifdef CONFIG_FAIR_GROUP_SCHED |
2872 | # ifdef CONFIG_SMP | |
cef27403 PZ |
2873 | /* |
2874 | * All this does is approximate the hierarchical proportion which includes that | |
2875 | * global sum we all love to hate. | |
2876 | * | |
2877 | * That is, the weight of a group entity, is the proportional share of the | |
2878 | * group weight based on the group runqueue weights. That is: | |
2879 | * | |
2880 | * tg->weight * grq->load.weight | |
2881 | * ge->load.weight = ----------------------------- (1) | |
2882 | * \Sum grq->load.weight | |
2883 | * | |
2884 | * Now, because computing that sum is prohibitively expensive to compute (been | |
2885 | * there, done that) we approximate it with this average stuff. The average | |
2886 | * moves slower and therefore the approximation is cheaper and more stable. | |
2887 | * | |
2888 | * So instead of the above, we substitute: | |
2889 | * | |
2890 | * grq->load.weight -> grq->avg.load_avg (2) | |
2891 | * | |
2892 | * which yields the following: | |
2893 | * | |
2894 | * tg->weight * grq->avg.load_avg | |
2895 | * ge->load.weight = ------------------------------ (3) | |
2896 | * tg->load_avg | |
2897 | * | |
2898 | * Where: tg->load_avg ~= \Sum grq->avg.load_avg | |
2899 | * | |
2900 | * That is shares_avg, and it is right (given the approximation (2)). | |
2901 | * | |
2902 | * The problem with it is that because the average is slow -- it was designed | |
2903 | * to be exactly that of course -- this leads to transients in boundary | |
2904 | * conditions. In specific, the case where the group was idle and we start the | |
2905 | * one task. It takes time for our CPU's grq->avg.load_avg to build up, | |
2906 | * yielding bad latency etc.. | |
2907 | * | |
2908 | * Now, in that special case (1) reduces to: | |
2909 | * | |
2910 | * tg->weight * grq->load.weight | |
17de4ee0 | 2911 | * ge->load.weight = ----------------------------- = tg->weight (4) |
cef27403 PZ |
2912 | * grp->load.weight |
2913 | * | |
2914 | * That is, the sum collapses because all other CPUs are idle; the UP scenario. | |
2915 | * | |
2916 | * So what we do is modify our approximation (3) to approach (4) in the (near) | |
2917 | * UP case, like: | |
2918 | * | |
2919 | * ge->load.weight = | |
2920 | * | |
2921 | * tg->weight * grq->load.weight | |
2922 | * --------------------------------------------------- (5) | |
2923 | * tg->load_avg - grq->avg.load_avg + grq->load.weight | |
2924 | * | |
17de4ee0 PZ |
2925 | * But because grq->load.weight can drop to 0, resulting in a divide by zero, |
2926 | * we need to use grq->avg.load_avg as its lower bound, which then gives: | |
2927 | * | |
2928 | * | |
2929 | * tg->weight * grq->load.weight | |
2930 | * ge->load.weight = ----------------------------- (6) | |
2931 | * tg_load_avg' | |
2932 | * | |
2933 | * Where: | |
2934 | * | |
2935 | * tg_load_avg' = tg->load_avg - grq->avg.load_avg + | |
2936 | * max(grq->load.weight, grq->avg.load_avg) | |
cef27403 PZ |
2937 | * |
2938 | * And that is shares_weight and is icky. In the (near) UP case it approaches | |
2939 | * (4) while in the normal case it approaches (3). It consistently | |
2940 | * overestimates the ge->load.weight and therefore: | |
2941 | * | |
2942 | * \Sum ge->load.weight >= tg->weight | |
2943 | * | |
2944 | * hence icky! | |
2945 | */ | |
2c8e4dce | 2946 | static long calc_group_shares(struct cfs_rq *cfs_rq) |
cf5f0acf | 2947 | { |
7c80cfc9 PZ |
2948 | long tg_weight, tg_shares, load, shares; |
2949 | struct task_group *tg = cfs_rq->tg; | |
2950 | ||
2951 | tg_shares = READ_ONCE(tg->shares); | |
cf5f0acf | 2952 | |
3d4b60d3 | 2953 | load = max(scale_load_down(cfs_rq->load.weight), cfs_rq->avg.load_avg); |
cf5f0acf | 2954 | |
ea1dc6fc | 2955 | tg_weight = atomic_long_read(&tg->load_avg); |
3ff6dcac | 2956 | |
ea1dc6fc PZ |
2957 | /* Ensure tg_weight >= load */ |
2958 | tg_weight -= cfs_rq->tg_load_avg_contrib; | |
2959 | tg_weight += load; | |
3ff6dcac | 2960 | |
7c80cfc9 | 2961 | shares = (tg_shares * load); |
cf5f0acf PZ |
2962 | if (tg_weight) |
2963 | shares /= tg_weight; | |
3ff6dcac | 2964 | |
b8fd8423 DE |
2965 | /* |
2966 | * MIN_SHARES has to be unscaled here to support per-CPU partitioning | |
2967 | * of a group with small tg->shares value. It is a floor value which is | |
2968 | * assigned as a minimum load.weight to the sched_entity representing | |
2969 | * the group on a CPU. | |
2970 | * | |
2971 | * E.g. on 64-bit for a group with tg->shares of scale_load(15)=15*1024 | |
2972 | * on an 8-core system with 8 tasks each runnable on one CPU shares has | |
2973 | * to be 15*1024*1/8=1920 instead of scale_load(MIN_SHARES)=2*1024. In | |
2974 | * case no task is runnable on a CPU MIN_SHARES=2 should be returned | |
2975 | * instead of 0. | |
2976 | */ | |
7c80cfc9 | 2977 | return clamp_t(long, shares, MIN_SHARES, tg_shares); |
3ff6dcac | 2978 | } |
2c8e4dce JB |
2979 | |
2980 | /* | |
17de4ee0 PZ |
2981 | * This calculates the effective runnable weight for a group entity based on |
2982 | * the group entity weight calculated above. | |
2983 | * | |
2984 | * Because of the above approximation (2), our group entity weight is | |
2985 | * an load_avg based ratio (3). This means that it includes blocked load and | |
2986 | * does not represent the runnable weight. | |
2987 | * | |
2988 | * Approximate the group entity's runnable weight per ratio from the group | |
2989 | * runqueue: | |
2990 | * | |
2991 | * grq->avg.runnable_load_avg | |
2992 | * ge->runnable_weight = ge->load.weight * -------------------------- (7) | |
2993 | * grq->avg.load_avg | |
2994 | * | |
2995 | * However, analogous to above, since the avg numbers are slow, this leads to | |
2996 | * transients in the from-idle case. Instead we use: | |
2997 | * | |
2998 | * ge->runnable_weight = ge->load.weight * | |
2999 | * | |
3000 | * max(grq->avg.runnable_load_avg, grq->runnable_weight) | |
3001 | * ----------------------------------------------------- (8) | |
3002 | * max(grq->avg.load_avg, grq->load.weight) | |
3003 | * | |
3004 | * Where these max() serve both to use the 'instant' values to fix the slow | |
3005 | * from-idle and avoid the /0 on to-idle, similar to (6). | |
2c8e4dce JB |
3006 | */ |
3007 | static long calc_group_runnable(struct cfs_rq *cfs_rq, long shares) | |
3008 | { | |
17de4ee0 PZ |
3009 | long runnable, load_avg; |
3010 | ||
3011 | load_avg = max(cfs_rq->avg.load_avg, | |
3012 | scale_load_down(cfs_rq->load.weight)); | |
3013 | ||
3014 | runnable = max(cfs_rq->avg.runnable_load_avg, | |
3015 | scale_load_down(cfs_rq->runnable_weight)); | |
2c8e4dce JB |
3016 | |
3017 | runnable *= shares; | |
3018 | if (load_avg) | |
3019 | runnable /= load_avg; | |
17de4ee0 | 3020 | |
2c8e4dce JB |
3021 | return clamp_t(long, runnable, MIN_SHARES, shares); |
3022 | } | |
3ff6dcac | 3023 | # endif /* CONFIG_SMP */ |
ea1dc6fc | 3024 | |
82958366 PT |
3025 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq); |
3026 | ||
1ea6c46a PZ |
3027 | /* |
3028 | * Recomputes the group entity based on the current state of its group | |
3029 | * runqueue. | |
3030 | */ | |
3031 | static void update_cfs_group(struct sched_entity *se) | |
2069dd75 | 3032 | { |
1ea6c46a PZ |
3033 | struct cfs_rq *gcfs_rq = group_cfs_rq(se); |
3034 | long shares, runnable; | |
2069dd75 | 3035 | |
1ea6c46a | 3036 | if (!gcfs_rq) |
89ee048f VG |
3037 | return; |
3038 | ||
1ea6c46a | 3039 | if (throttled_hierarchy(gcfs_rq)) |
2069dd75 | 3040 | return; |
89ee048f | 3041 | |
3ff6dcac | 3042 | #ifndef CONFIG_SMP |
1ea6c46a | 3043 | runnable = shares = READ_ONCE(gcfs_rq->tg->shares); |
7c80cfc9 PZ |
3044 | |
3045 | if (likely(se->load.weight == shares)) | |
3ff6dcac | 3046 | return; |
7c80cfc9 | 3047 | #else |
2c8e4dce JB |
3048 | shares = calc_group_shares(gcfs_rq); |
3049 | runnable = calc_group_runnable(gcfs_rq, shares); | |
3ff6dcac | 3050 | #endif |
2069dd75 | 3051 | |
1ea6c46a | 3052 | reweight_entity(cfs_rq_of(se), se, shares, runnable); |
2069dd75 | 3053 | } |
89ee048f | 3054 | |
2069dd75 | 3055 | #else /* CONFIG_FAIR_GROUP_SCHED */ |
1ea6c46a | 3056 | static inline void update_cfs_group(struct sched_entity *se) |
2069dd75 PZ |
3057 | { |
3058 | } | |
3059 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
3060 | ||
a030d738 VK |
3061 | static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq) |
3062 | { | |
43964409 LT |
3063 | struct rq *rq = rq_of(cfs_rq); |
3064 | ||
3065 | if (&rq->cfs == cfs_rq) { | |
a030d738 VK |
3066 | /* |
3067 | * There are a few boundary cases this might miss but it should | |
3068 | * get called often enough that that should (hopefully) not be | |
3069 | * a real problem -- added to that it only calls on the local | |
3070 | * CPU, so if we enqueue remotely we'll miss an update, but | |
3071 | * the next tick/schedule should update. | |
3072 | * | |
3073 | * It will not get called when we go idle, because the idle | |
3074 | * thread is a different class (!fair), nor will the utilization | |
3075 | * number include things like RT tasks. | |
3076 | * | |
3077 | * As is, the util number is not freq-invariant (we'd have to | |
3078 | * implement arch_scale_freq_capacity() for that). | |
3079 | * | |
3080 | * See cpu_util(). | |
3081 | */ | |
43964409 | 3082 | cpufreq_update_util(rq, 0); |
a030d738 VK |
3083 | } |
3084 | } | |
3085 | ||
141965c7 | 3086 | #ifdef CONFIG_SMP |
9d85f21c PT |
3087 | /* |
3088 | * Approximate: | |
3089 | * val * y^n, where y^32 ~= 0.5 (~1 scheduling period) | |
3090 | */ | |
a481db34 | 3091 | static u64 decay_load(u64 val, u64 n) |
9d85f21c | 3092 | { |
5b51f2f8 PT |
3093 | unsigned int local_n; |
3094 | ||
05296e75 | 3095 | if (unlikely(n > LOAD_AVG_PERIOD * 63)) |
5b51f2f8 PT |
3096 | return 0; |
3097 | ||
3098 | /* after bounds checking we can collapse to 32-bit */ | |
3099 | local_n = n; | |
3100 | ||
3101 | /* | |
3102 | * As y^PERIOD = 1/2, we can combine | |
9c58c79a ZZ |
3103 | * y^n = 1/2^(n/PERIOD) * y^(n%PERIOD) |
3104 | * With a look-up table which covers y^n (n<PERIOD) | |
5b51f2f8 PT |
3105 | * |
3106 | * To achieve constant time decay_load. | |
3107 | */ | |
3108 | if (unlikely(local_n >= LOAD_AVG_PERIOD)) { | |
3109 | val >>= local_n / LOAD_AVG_PERIOD; | |
3110 | local_n %= LOAD_AVG_PERIOD; | |
9d85f21c PT |
3111 | } |
3112 | ||
9d89c257 YD |
3113 | val = mul_u64_u32_shr(val, runnable_avg_yN_inv[local_n], 32); |
3114 | return val; | |
5b51f2f8 PT |
3115 | } |
3116 | ||
05296e75 | 3117 | static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3) |
5b51f2f8 | 3118 | { |
05296e75 | 3119 | u32 c1, c2, c3 = d3; /* y^0 == 1 */ |
5b51f2f8 | 3120 | |
a481db34 | 3121 | /* |
3841cdc3 | 3122 | * c1 = d1 y^p |
a481db34 | 3123 | */ |
05296e75 | 3124 | c1 = decay_load((u64)d1, periods); |
a481db34 | 3125 | |
a481db34 | 3126 | /* |
3841cdc3 | 3127 | * p-1 |
05296e75 PZ |
3128 | * c2 = 1024 \Sum y^n |
3129 | * n=1 | |
a481db34 | 3130 | * |
05296e75 PZ |
3131 | * inf inf |
3132 | * = 1024 ( \Sum y^n - \Sum y^n - y^0 ) | |
3841cdc3 | 3133 | * n=0 n=p |
a481db34 | 3134 | */ |
05296e75 | 3135 | c2 = LOAD_AVG_MAX - decay_load(LOAD_AVG_MAX, periods) - 1024; |
a481db34 YD |
3136 | |
3137 | return c1 + c2 + c3; | |
9d85f21c PT |
3138 | } |
3139 | ||
54a21385 | 3140 | #define cap_scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT) |
e0f5f3af | 3141 | |
a481db34 YD |
3142 | /* |
3143 | * Accumulate the three separate parts of the sum; d1 the remainder | |
3144 | * of the last (incomplete) period, d2 the span of full periods and d3 | |
3145 | * the remainder of the (incomplete) current period. | |
3146 | * | |
3147 | * d1 d2 d3 | |
3148 | * ^ ^ ^ | |
3149 | * | | | | |
3150 | * |<->|<----------------->|<--->| | |
3151 | * ... |---x---|------| ... |------|-----x (now) | |
3152 | * | |
3841cdc3 PZ |
3153 | * p-1 |
3154 | * u' = (u + d1) y^p + 1024 \Sum y^n + d3 y^0 | |
3155 | * n=1 | |
a481db34 | 3156 | * |
3841cdc3 | 3157 | * = u y^p + (Step 1) |
a481db34 | 3158 | * |
3841cdc3 PZ |
3159 | * p-1 |
3160 | * d1 y^p + 1024 \Sum y^n + d3 y^0 (Step 2) | |
3161 | * n=1 | |
a481db34 YD |
3162 | */ |
3163 | static __always_inline u32 | |
3164 | accumulate_sum(u64 delta, int cpu, struct sched_avg *sa, | |
1ea6c46a | 3165 | unsigned long load, unsigned long runnable, int running) |
a481db34 YD |
3166 | { |
3167 | unsigned long scale_freq, scale_cpu; | |
05296e75 | 3168 | u32 contrib = (u32)delta; /* p == 0 -> delta < 1024 */ |
a481db34 | 3169 | u64 periods; |
a481db34 YD |
3170 | |
3171 | scale_freq = arch_scale_freq_capacity(NULL, cpu); | |
3172 | scale_cpu = arch_scale_cpu_capacity(NULL, cpu); | |
3173 | ||
3174 | delta += sa->period_contrib; | |
3175 | periods = delta / 1024; /* A period is 1024us (~1ms) */ | |
3176 | ||
3177 | /* | |
3178 | * Step 1: decay old *_sum if we crossed period boundaries. | |
3179 | */ | |
3180 | if (periods) { | |
3181 | sa->load_sum = decay_load(sa->load_sum, periods); | |
1ea6c46a PZ |
3182 | sa->runnable_load_sum = |
3183 | decay_load(sa->runnable_load_sum, periods); | |
a481db34 | 3184 | sa->util_sum = decay_load((u64)(sa->util_sum), periods); |
a481db34 | 3185 | |
05296e75 PZ |
3186 | /* |
3187 | * Step 2 | |
3188 | */ | |
3189 | delta %= 1024; | |
3190 | contrib = __accumulate_pelt_segments(periods, | |
3191 | 1024 - sa->period_contrib, delta); | |
3192 | } | |
a481db34 YD |
3193 | sa->period_contrib = delta; |
3194 | ||
3195 | contrib = cap_scale(contrib, scale_freq); | |
1ea6c46a PZ |
3196 | if (load) |
3197 | sa->load_sum += load * contrib; | |
3198 | if (runnable) | |
3199 | sa->runnable_load_sum += runnable * contrib; | |
a481db34 YD |
3200 | if (running) |
3201 | sa->util_sum += contrib * scale_cpu; | |
3202 | ||
3203 | return periods; | |
3204 | } | |
3205 | ||
9d85f21c PT |
3206 | /* |
3207 | * We can represent the historical contribution to runnable average as the | |
3208 | * coefficients of a geometric series. To do this we sub-divide our runnable | |
3209 | * history into segments of approximately 1ms (1024us); label the segment that | |
3210 | * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g. | |
3211 | * | |
3212 | * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ... | |
3213 | * p0 p1 p2 | |
3214 | * (now) (~1ms ago) (~2ms ago) | |
3215 | * | |
3216 | * Let u_i denote the fraction of p_i that the entity was runnable. | |
3217 | * | |
3218 | * We then designate the fractions u_i as our co-efficients, yielding the | |
3219 | * following representation of historical load: | |
3220 | * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ... | |
3221 | * | |
3222 | * We choose y based on the with of a reasonably scheduling period, fixing: | |
3223 | * y^32 = 0.5 | |
3224 | * | |
3225 | * This means that the contribution to load ~32ms ago (u_32) will be weighted | |
3226 | * approximately half as much as the contribution to load within the last ms | |
3227 | * (u_0). | |
3228 | * | |
3229 | * When a period "rolls over" and we have new u_0`, multiplying the previous | |
3230 | * sum again by y is sufficient to update: | |
3231 | * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... ) | |
3232 | * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}] | |
3233 | */ | |
9d89c257 | 3234 | static __always_inline int |
c7b50216 | 3235 | ___update_load_sum(u64 now, int cpu, struct sched_avg *sa, |
1ea6c46a | 3236 | unsigned long load, unsigned long runnable, int running) |
9d85f21c | 3237 | { |
a481db34 | 3238 | u64 delta; |
9d85f21c | 3239 | |
9d89c257 | 3240 | delta = now - sa->last_update_time; |
9d85f21c PT |
3241 | /* |
3242 | * This should only happen when time goes backwards, which it | |
3243 | * unfortunately does during sched clock init when we swap over to TSC. | |
3244 | */ | |
3245 | if ((s64)delta < 0) { | |
9d89c257 | 3246 | sa->last_update_time = now; |
9d85f21c PT |
3247 | return 0; |
3248 | } | |
3249 | ||
3250 | /* | |
3251 | * Use 1024ns as the unit of measurement since it's a reasonable | |
3252 | * approximation of 1us and fast to compute. | |
3253 | */ | |
3254 | delta >>= 10; | |
3255 | if (!delta) | |
3256 | return 0; | |
bb0bd044 PZ |
3257 | |
3258 | sa->last_update_time += delta << 10; | |
9d85f21c | 3259 | |
f235a54f VG |
3260 | /* |
3261 | * running is a subset of runnable (weight) so running can't be set if | |
3262 | * runnable is clear. But there are some corner cases where the current | |
3263 | * se has been already dequeued but cfs_rq->curr still points to it. | |
3264 | * This means that weight will be 0 but not running for a sched_entity | |
3265 | * but also for a cfs_rq if the latter becomes idle. As an example, | |
3266 | * this happens during idle_balance() which calls | |
3267 | * update_blocked_averages() | |
3268 | */ | |
1ea6c46a PZ |
3269 | if (!load) |
3270 | runnable = running = 0; | |
f235a54f | 3271 | |
a481db34 YD |
3272 | /* |
3273 | * Now we know we crossed measurement unit boundaries. The *_avg | |
3274 | * accrues by two steps: | |
3275 | * | |
3276 | * Step 1: accumulate *_sum since last_update_time. If we haven't | |
3277 | * crossed period boundaries, finish. | |
3278 | */ | |
1ea6c46a | 3279 | if (!accumulate_sum(delta, cpu, sa, load, runnable, running)) |
a481db34 | 3280 | return 0; |
9ee474f5 | 3281 | |
c7b50216 PZ |
3282 | return 1; |
3283 | } | |
3284 | ||
3285 | static __always_inline void | |
1ea6c46a | 3286 | ___update_load_avg(struct sched_avg *sa, unsigned long load, unsigned long runnable) |
c7b50216 PZ |
3287 | { |
3288 | u32 divider = LOAD_AVG_MAX - 1024 + sa->period_contrib; | |
3289 | ||
a481db34 YD |
3290 | /* |
3291 | * Step 2: update *_avg. | |
3292 | */ | |
1ea6c46a PZ |
3293 | sa->load_avg = div_u64(load * sa->load_sum, divider); |
3294 | sa->runnable_load_avg = div_u64(runnable * sa->runnable_load_sum, divider); | |
c7b50216 PZ |
3295 | sa->util_avg = sa->util_sum / divider; |
3296 | } | |
aff3e498 | 3297 | |
c7b50216 PZ |
3298 | /* |
3299 | * sched_entity: | |
3300 | * | |
1ea6c46a PZ |
3301 | * task: |
3302 | * se_runnable() == se_weight() | |
3303 | * | |
3304 | * group: [ see update_cfs_group() ] | |
3305 | * se_weight() = tg->weight * grq->load_avg / tg->load_avg | |
3306 | * se_runnable() = se_weight(se) * grq->runnable_load_avg / grq->load_avg | |
3307 | * | |
c7b50216 PZ |
3308 | * load_sum := runnable_sum |
3309 | * load_avg = se_weight(se) * runnable_avg | |
3310 | * | |
1ea6c46a PZ |
3311 | * runnable_load_sum := runnable_sum |
3312 | * runnable_load_avg = se_runnable(se) * runnable_avg | |
3313 | * | |
3314 | * XXX collapse load_sum and runnable_load_sum | |
3315 | * | |
c7b50216 PZ |
3316 | * cfq_rs: |
3317 | * | |
3318 | * load_sum = \Sum se_weight(se) * se->avg.load_sum | |
3319 | * load_avg = \Sum se->avg.load_avg | |
1ea6c46a PZ |
3320 | * |
3321 | * runnable_load_sum = \Sum se_runnable(se) * se->avg.runnable_load_sum | |
3322 | * runnable_load_avg = \Sum se->avg.runable_load_avg | |
c7b50216 PZ |
3323 | */ |
3324 | ||
0ccb977f PZ |
3325 | static int |
3326 | __update_load_avg_blocked_se(u64 now, int cpu, struct sched_entity *se) | |
3327 | { | |
1ea6c46a PZ |
3328 | if (entity_is_task(se)) |
3329 | se->runnable_weight = se->load.weight; | |
3330 | ||
3331 | if (___update_load_sum(now, cpu, &se->avg, 0, 0, 0)) { | |
3332 | ___update_load_avg(&se->avg, se_weight(se), se_runnable(se)); | |
c7b50216 PZ |
3333 | return 1; |
3334 | } | |
3335 | ||
3336 | return 0; | |
0ccb977f PZ |
3337 | } |
3338 | ||
3339 | static int | |
3340 | __update_load_avg_se(u64 now, int cpu, struct cfs_rq *cfs_rq, struct sched_entity *se) | |
3341 | { | |
1ea6c46a PZ |
3342 | if (entity_is_task(se)) |
3343 | se->runnable_weight = se->load.weight; | |
3344 | ||
3345 | if (___update_load_sum(now, cpu, &se->avg, !!se->on_rq, !!se->on_rq, | |
3346 | cfs_rq->curr == se)) { | |
c7b50216 | 3347 | |
1ea6c46a | 3348 | ___update_load_avg(&se->avg, se_weight(se), se_runnable(se)); |
c7b50216 PZ |
3349 | return 1; |
3350 | } | |
3351 | ||
3352 | return 0; | |
0ccb977f PZ |
3353 | } |
3354 | ||
3355 | static int | |
3356 | __update_load_avg_cfs_rq(u64 now, int cpu, struct cfs_rq *cfs_rq) | |
3357 | { | |
c7b50216 PZ |
3358 | if (___update_load_sum(now, cpu, &cfs_rq->avg, |
3359 | scale_load_down(cfs_rq->load.weight), | |
1ea6c46a PZ |
3360 | scale_load_down(cfs_rq->runnable_weight), |
3361 | cfs_rq->curr != NULL)) { | |
3362 | ||
3363 | ___update_load_avg(&cfs_rq->avg, 1, 1); | |
c7b50216 PZ |
3364 | return 1; |
3365 | } | |
3366 | ||
3367 | return 0; | |
0ccb977f PZ |
3368 | } |
3369 | ||
c566e8e9 | 3370 | #ifdef CONFIG_FAIR_GROUP_SCHED |
7c3edd2c PZ |
3371 | /** |
3372 | * update_tg_load_avg - update the tg's load avg | |
3373 | * @cfs_rq: the cfs_rq whose avg changed | |
3374 | * @force: update regardless of how small the difference | |
3375 | * | |
3376 | * This function 'ensures': tg->load_avg := \Sum tg->cfs_rq[]->avg.load. | |
3377 | * However, because tg->load_avg is a global value there are performance | |
3378 | * considerations. | |
3379 | * | |
3380 | * In order to avoid having to look at the other cfs_rq's, we use a | |
3381 | * differential update where we store the last value we propagated. This in | |
3382 | * turn allows skipping updates if the differential is 'small'. | |
3383 | * | |
815abf5a | 3384 | * Updating tg's load_avg is necessary before update_cfs_share(). |
bb17f655 | 3385 | */ |
9d89c257 | 3386 | static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force) |
bb17f655 | 3387 | { |
9d89c257 | 3388 | long delta = cfs_rq->avg.load_avg - cfs_rq->tg_load_avg_contrib; |
bb17f655 | 3389 | |
aa0b7ae0 WL |
3390 | /* |
3391 | * No need to update load_avg for root_task_group as it is not used. | |
3392 | */ | |
3393 | if (cfs_rq->tg == &root_task_group) | |
3394 | return; | |
3395 | ||
9d89c257 YD |
3396 | if (force || abs(delta) > cfs_rq->tg_load_avg_contrib / 64) { |
3397 | atomic_long_add(delta, &cfs_rq->tg->load_avg); | |
3398 | cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg; | |
bb17f655 | 3399 | } |
8165e145 | 3400 | } |
f5f9739d | 3401 | |
ad936d86 BP |
3402 | /* |
3403 | * Called within set_task_rq() right before setting a task's cpu. The | |
3404 | * caller only guarantees p->pi_lock is held; no other assumptions, | |
3405 | * including the state of rq->lock, should be made. | |
3406 | */ | |
3407 | void set_task_rq_fair(struct sched_entity *se, | |
3408 | struct cfs_rq *prev, struct cfs_rq *next) | |
3409 | { | |
0ccb977f PZ |
3410 | u64 p_last_update_time; |
3411 | u64 n_last_update_time; | |
3412 | ||
ad936d86 BP |
3413 | if (!sched_feat(ATTACH_AGE_LOAD)) |
3414 | return; | |
3415 | ||
3416 | /* | |
3417 | * We are supposed to update the task to "current" time, then its up to | |
3418 | * date and ready to go to new CPU/cfs_rq. But we have difficulty in | |
3419 | * getting what current time is, so simply throw away the out-of-date | |
3420 | * time. This will result in the wakee task is less decayed, but giving | |
3421 | * the wakee more load sounds not bad. | |
3422 | */ | |
0ccb977f PZ |
3423 | if (!(se->avg.last_update_time && prev)) |
3424 | return; | |
ad936d86 BP |
3425 | |
3426 | #ifndef CONFIG_64BIT | |
0ccb977f | 3427 | { |
ad936d86 BP |
3428 | u64 p_last_update_time_copy; |
3429 | u64 n_last_update_time_copy; | |
3430 | ||
3431 | do { | |
3432 | p_last_update_time_copy = prev->load_last_update_time_copy; | |
3433 | n_last_update_time_copy = next->load_last_update_time_copy; | |
3434 | ||
3435 | smp_rmb(); | |
3436 | ||
3437 | p_last_update_time = prev->avg.last_update_time; | |
3438 | n_last_update_time = next->avg.last_update_time; | |
3439 | ||
3440 | } while (p_last_update_time != p_last_update_time_copy || | |
3441 | n_last_update_time != n_last_update_time_copy); | |
0ccb977f | 3442 | } |
ad936d86 | 3443 | #else |
0ccb977f PZ |
3444 | p_last_update_time = prev->avg.last_update_time; |
3445 | n_last_update_time = next->avg.last_update_time; | |
ad936d86 | 3446 | #endif |
0ccb977f PZ |
3447 | __update_load_avg_blocked_se(p_last_update_time, cpu_of(rq_of(prev)), se); |
3448 | se->avg.last_update_time = n_last_update_time; | |
ad936d86 | 3449 | } |
09a43ace | 3450 | |
0e2d2aaa PZ |
3451 | |
3452 | /* | |
3453 | * When on migration a sched_entity joins/leaves the PELT hierarchy, we need to | |
3454 | * propagate its contribution. The key to this propagation is the invariant | |
3455 | * that for each group: | |
3456 | * | |
3457 | * ge->avg == grq->avg (1) | |
3458 | * | |
3459 | * _IFF_ we look at the pure running and runnable sums. Because they | |
3460 | * represent the very same entity, just at different points in the hierarchy. | |
3461 | * | |
a4c3c049 VG |
3462 | * Per the above update_tg_cfs_util() is trivial and simply copies the running |
3463 | * sum over (but still wrong, because the group entity and group rq do not have | |
3464 | * their PELT windows aligned). | |
0e2d2aaa PZ |
3465 | * |
3466 | * However, update_tg_cfs_runnable() is more complex. So we have: | |
3467 | * | |
3468 | * ge->avg.load_avg = ge->load.weight * ge->avg.runnable_avg (2) | |
3469 | * | |
3470 | * And since, like util, the runnable part should be directly transferable, | |
3471 | * the following would _appear_ to be the straight forward approach: | |
3472 | * | |
a4c3c049 | 3473 | * grq->avg.load_avg = grq->load.weight * grq->avg.runnable_avg (3) |
0e2d2aaa PZ |
3474 | * |
3475 | * And per (1) we have: | |
3476 | * | |
a4c3c049 | 3477 | * ge->avg.runnable_avg == grq->avg.runnable_avg |
0e2d2aaa PZ |
3478 | * |
3479 | * Which gives: | |
3480 | * | |
3481 | * ge->load.weight * grq->avg.load_avg | |
3482 | * ge->avg.load_avg = ----------------------------------- (4) | |
3483 | * grq->load.weight | |
3484 | * | |
3485 | * Except that is wrong! | |
3486 | * | |
3487 | * Because while for entities historical weight is not important and we | |
3488 | * really only care about our future and therefore can consider a pure | |
3489 | * runnable sum, runqueues can NOT do this. | |
3490 | * | |
3491 | * We specifically want runqueues to have a load_avg that includes | |
3492 | * historical weights. Those represent the blocked load, the load we expect | |
3493 | * to (shortly) return to us. This only works by keeping the weights as | |
3494 | * integral part of the sum. We therefore cannot decompose as per (3). | |
3495 | * | |
a4c3c049 VG |
3496 | * Another reason this doesn't work is that runnable isn't a 0-sum entity. |
3497 | * Imagine a rq with 2 tasks that each are runnable 2/3 of the time. Then the | |
3498 | * rq itself is runnable anywhere between 2/3 and 1 depending on how the | |
3499 | * runnable section of these tasks overlap (or not). If they were to perfectly | |
3500 | * align the rq as a whole would be runnable 2/3 of the time. If however we | |
3501 | * always have at least 1 runnable task, the rq as a whole is always runnable. | |
0e2d2aaa | 3502 | * |
a4c3c049 | 3503 | * So we'll have to approximate.. :/ |
0e2d2aaa | 3504 | * |
a4c3c049 | 3505 | * Given the constraint: |
0e2d2aaa | 3506 | * |
a4c3c049 | 3507 | * ge->avg.running_sum <= ge->avg.runnable_sum <= LOAD_AVG_MAX |
0e2d2aaa | 3508 | * |
a4c3c049 VG |
3509 | * We can construct a rule that adds runnable to a rq by assuming minimal |
3510 | * overlap. | |
0e2d2aaa | 3511 | * |
a4c3c049 | 3512 | * On removal, we'll assume each task is equally runnable; which yields: |
0e2d2aaa | 3513 | * |
a4c3c049 | 3514 | * grq->avg.runnable_sum = grq->avg.load_sum / grq->load.weight |
0e2d2aaa | 3515 | * |
a4c3c049 | 3516 | * XXX: only do this for the part of runnable > running ? |
0e2d2aaa | 3517 | * |
0e2d2aaa PZ |
3518 | */ |
3519 | ||
09a43ace | 3520 | static inline void |
0e2d2aaa | 3521 | update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq) |
09a43ace | 3522 | { |
09a43ace VG |
3523 | long delta = gcfs_rq->avg.util_avg - se->avg.util_avg; |
3524 | ||
3525 | /* Nothing to update */ | |
3526 | if (!delta) | |
3527 | return; | |
3528 | ||
a4c3c049 VG |
3529 | /* |
3530 | * The relation between sum and avg is: | |
3531 | * | |
3532 | * LOAD_AVG_MAX - 1024 + sa->period_contrib | |
3533 | * | |
3534 | * however, the PELT windows are not aligned between grq and gse. | |
3535 | */ | |
3536 | ||
09a43ace VG |
3537 | /* Set new sched_entity's utilization */ |
3538 | se->avg.util_avg = gcfs_rq->avg.util_avg; | |
3539 | se->avg.util_sum = se->avg.util_avg * LOAD_AVG_MAX; | |
3540 | ||
3541 | /* Update parent cfs_rq utilization */ | |
3542 | add_positive(&cfs_rq->avg.util_avg, delta); | |
3543 | cfs_rq->avg.util_sum = cfs_rq->avg.util_avg * LOAD_AVG_MAX; | |
3544 | } | |
3545 | ||
09a43ace | 3546 | static inline void |
0e2d2aaa | 3547 | update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq) |
09a43ace | 3548 | { |
a4c3c049 VG |
3549 | long delta_avg, running_sum, runnable_sum = gcfs_rq->prop_runnable_sum; |
3550 | unsigned long runnable_load_avg, load_avg; | |
3551 | u64 runnable_load_sum, load_sum = 0; | |
3552 | s64 delta_sum; | |
09a43ace | 3553 | |
0e2d2aaa PZ |
3554 | if (!runnable_sum) |
3555 | return; | |
09a43ace | 3556 | |
0e2d2aaa | 3557 | gcfs_rq->prop_runnable_sum = 0; |
09a43ace | 3558 | |
a4c3c049 VG |
3559 | if (runnable_sum >= 0) { |
3560 | /* | |
3561 | * Add runnable; clip at LOAD_AVG_MAX. Reflects that until | |
3562 | * the CPU is saturated running == runnable. | |
3563 | */ | |
3564 | runnable_sum += se->avg.load_sum; | |
3565 | runnable_sum = min(runnable_sum, (long)LOAD_AVG_MAX); | |
3566 | } else { | |
3567 | /* | |
3568 | * Estimate the new unweighted runnable_sum of the gcfs_rq by | |
3569 | * assuming all tasks are equally runnable. | |
3570 | */ | |
3571 | if (scale_load_down(gcfs_rq->load.weight)) { | |
3572 | load_sum = div_s64(gcfs_rq->avg.load_sum, | |
3573 | scale_load_down(gcfs_rq->load.weight)); | |
3574 | } | |
3575 | ||
3576 | /* But make sure to not inflate se's runnable */ | |
3577 | runnable_sum = min(se->avg.load_sum, load_sum); | |
3578 | } | |
3579 | ||
3580 | /* | |
3581 | * runnable_sum can't be lower than running_sum | |
3582 | * As running sum is scale with cpu capacity wehreas the runnable sum | |
3583 | * is not we rescale running_sum 1st | |
3584 | */ | |
3585 | running_sum = se->avg.util_sum / | |
3586 | arch_scale_cpu_capacity(NULL, cpu_of(rq_of(cfs_rq))); | |
3587 | runnable_sum = max(runnable_sum, running_sum); | |
3588 | ||
0e2d2aaa PZ |
3589 | load_sum = (s64)se_weight(se) * runnable_sum; |
3590 | load_avg = div_s64(load_sum, LOAD_AVG_MAX); | |
09a43ace | 3591 | |
a4c3c049 VG |
3592 | delta_sum = load_sum - (s64)se_weight(se) * se->avg.load_sum; |
3593 | delta_avg = load_avg - se->avg.load_avg; | |
09a43ace | 3594 | |
a4c3c049 VG |
3595 | se->avg.load_sum = runnable_sum; |
3596 | se->avg.load_avg = load_avg; | |
3597 | add_positive(&cfs_rq->avg.load_avg, delta_avg); | |
3598 | add_positive(&cfs_rq->avg.load_sum, delta_sum); | |
09a43ace | 3599 | |
1ea6c46a PZ |
3600 | runnable_load_sum = (s64)se_runnable(se) * runnable_sum; |
3601 | runnable_load_avg = div_s64(runnable_load_sum, LOAD_AVG_MAX); | |
a4c3c049 VG |
3602 | delta_sum = runnable_load_sum - se_weight(se) * se->avg.runnable_load_sum; |
3603 | delta_avg = runnable_load_avg - se->avg.runnable_load_avg; | |
1ea6c46a | 3604 | |
a4c3c049 VG |
3605 | se->avg.runnable_load_sum = runnable_sum; |
3606 | se->avg.runnable_load_avg = runnable_load_avg; | |
1ea6c46a | 3607 | |
09a43ace | 3608 | if (se->on_rq) { |
a4c3c049 VG |
3609 | add_positive(&cfs_rq->avg.runnable_load_avg, delta_avg); |
3610 | add_positive(&cfs_rq->avg.runnable_load_sum, delta_sum); | |
09a43ace VG |
3611 | } |
3612 | } | |
3613 | ||
0e2d2aaa | 3614 | static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum) |
09a43ace | 3615 | { |
0e2d2aaa PZ |
3616 | cfs_rq->propagate = 1; |
3617 | cfs_rq->prop_runnable_sum += runnable_sum; | |
09a43ace VG |
3618 | } |
3619 | ||
3620 | /* Update task and its cfs_rq load average */ | |
3621 | static inline int propagate_entity_load_avg(struct sched_entity *se) | |
3622 | { | |
0e2d2aaa | 3623 | struct cfs_rq *cfs_rq, *gcfs_rq; |
09a43ace VG |
3624 | |
3625 | if (entity_is_task(se)) | |
3626 | return 0; | |
3627 | ||
0e2d2aaa PZ |
3628 | gcfs_rq = group_cfs_rq(se); |
3629 | if (!gcfs_rq->propagate) | |
09a43ace VG |
3630 | return 0; |
3631 | ||
0e2d2aaa PZ |
3632 | gcfs_rq->propagate = 0; |
3633 | ||
09a43ace VG |
3634 | cfs_rq = cfs_rq_of(se); |
3635 | ||
0e2d2aaa | 3636 | add_tg_cfs_propagate(cfs_rq, gcfs_rq->prop_runnable_sum); |
09a43ace | 3637 | |
0e2d2aaa PZ |
3638 | update_tg_cfs_util(cfs_rq, se, gcfs_rq); |
3639 | update_tg_cfs_runnable(cfs_rq, se, gcfs_rq); | |
09a43ace VG |
3640 | |
3641 | return 1; | |
3642 | } | |
3643 | ||
bc427898 VG |
3644 | /* |
3645 | * Check if we need to update the load and the utilization of a blocked | |
3646 | * group_entity: | |
3647 | */ | |
3648 | static inline bool skip_blocked_update(struct sched_entity *se) | |
3649 | { | |
3650 | struct cfs_rq *gcfs_rq = group_cfs_rq(se); | |
3651 | ||
3652 | /* | |
3653 | * If sched_entity still have not zero load or utilization, we have to | |
3654 | * decay it: | |
3655 | */ | |
3656 | if (se->avg.load_avg || se->avg.util_avg) | |
3657 | return false; | |
3658 | ||
3659 | /* | |
3660 | * If there is a pending propagation, we have to update the load and | |
3661 | * the utilization of the sched_entity: | |
3662 | */ | |
0e2d2aaa | 3663 | if (gcfs_rq->propagate) |
bc427898 VG |
3664 | return false; |
3665 | ||
3666 | /* | |
3667 | * Otherwise, the load and the utilization of the sched_entity is | |
3668 | * already zero and there is no pending propagation, so it will be a | |
3669 | * waste of time to try to decay it: | |
3670 | */ | |
3671 | return true; | |
3672 | } | |
3673 | ||
6e83125c | 3674 | #else /* CONFIG_FAIR_GROUP_SCHED */ |
09a43ace | 3675 | |
9d89c257 | 3676 | static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force) {} |
09a43ace VG |
3677 | |
3678 | static inline int propagate_entity_load_avg(struct sched_entity *se) | |
3679 | { | |
3680 | return 0; | |
3681 | } | |
3682 | ||
0e2d2aaa | 3683 | static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum) {} |
09a43ace | 3684 | |
6e83125c | 3685 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
c566e8e9 | 3686 | |
3d30544f PZ |
3687 | /** |
3688 | * update_cfs_rq_load_avg - update the cfs_rq's load/util averages | |
3689 | * @now: current time, as per cfs_rq_clock_task() | |
3690 | * @cfs_rq: cfs_rq to update | |
3d30544f PZ |
3691 | * |
3692 | * The cfs_rq avg is the direct sum of all its entities (blocked and runnable) | |
3693 | * avg. The immediate corollary is that all (fair) tasks must be attached, see | |
3694 | * post_init_entity_util_avg(). | |
3695 | * | |
3696 | * cfs_rq->avg is used for task_h_load() and update_cfs_share() for example. | |
3697 | * | |
7c3edd2c PZ |
3698 | * Returns true if the load decayed or we removed load. |
3699 | * | |
3700 | * Since both these conditions indicate a changed cfs_rq->avg.load we should | |
3701 | * call update_tg_load_avg() when this function returns true. | |
3d30544f | 3702 | */ |
a2c6c91f | 3703 | static inline int |
3a123bbb | 3704 | update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) |
2dac754e | 3705 | { |
0e2d2aaa | 3706 | unsigned long removed_load = 0, removed_util = 0, removed_runnable_sum = 0; |
9d89c257 | 3707 | struct sched_avg *sa = &cfs_rq->avg; |
2a2f5d4e | 3708 | int decayed = 0; |
2dac754e | 3709 | |
2a2f5d4e PZ |
3710 | if (cfs_rq->removed.nr) { |
3711 | unsigned long r; | |
9a2dd585 | 3712 | u32 divider = LOAD_AVG_MAX - 1024 + sa->period_contrib; |
2a2f5d4e PZ |
3713 | |
3714 | raw_spin_lock(&cfs_rq->removed.lock); | |
3715 | swap(cfs_rq->removed.util_avg, removed_util); | |
3716 | swap(cfs_rq->removed.load_avg, removed_load); | |
0e2d2aaa | 3717 | swap(cfs_rq->removed.runnable_sum, removed_runnable_sum); |
2a2f5d4e PZ |
3718 | cfs_rq->removed.nr = 0; |
3719 | raw_spin_unlock(&cfs_rq->removed.lock); | |
3720 | ||
2a2f5d4e | 3721 | r = removed_load; |
89741892 | 3722 | sub_positive(&sa->load_avg, r); |
9a2dd585 | 3723 | sub_positive(&sa->load_sum, r * divider); |
2dac754e | 3724 | |
2a2f5d4e | 3725 | r = removed_util; |
89741892 | 3726 | sub_positive(&sa->util_avg, r); |
9a2dd585 | 3727 | sub_positive(&sa->util_sum, r * divider); |
2a2f5d4e | 3728 | |
0e2d2aaa | 3729 | add_tg_cfs_propagate(cfs_rq, -(long)removed_runnable_sum); |
2a2f5d4e PZ |
3730 | |
3731 | decayed = 1; | |
9d89c257 | 3732 | } |
36ee28e4 | 3733 | |
2a2f5d4e | 3734 | decayed |= __update_load_avg_cfs_rq(now, cpu_of(rq_of(cfs_rq)), cfs_rq); |
36ee28e4 | 3735 | |
9d89c257 YD |
3736 | #ifndef CONFIG_64BIT |
3737 | smp_wmb(); | |
3738 | cfs_rq->load_last_update_time_copy = sa->last_update_time; | |
3739 | #endif | |
36ee28e4 | 3740 | |
2a2f5d4e | 3741 | if (decayed) |
a2c6c91f | 3742 | cfs_rq_util_change(cfs_rq); |
21e96f88 | 3743 | |
2a2f5d4e | 3744 | return decayed; |
21e96f88 SM |
3745 | } |
3746 | ||
3d30544f PZ |
3747 | /** |
3748 | * attach_entity_load_avg - attach this entity to its cfs_rq load avg | |
3749 | * @cfs_rq: cfs_rq to attach to | |
3750 | * @se: sched_entity to attach | |
3751 | * | |
3752 | * Must call update_cfs_rq_load_avg() before this, since we rely on | |
3753 | * cfs_rq->avg.last_update_time being current. | |
3754 | */ | |
a05e8c51 BP |
3755 | static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) |
3756 | { | |
f207934f PZ |
3757 | u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib; |
3758 | ||
3759 | /* | |
3760 | * When we attach the @se to the @cfs_rq, we must align the decay | |
3761 | * window because without that, really weird and wonderful things can | |
3762 | * happen. | |
3763 | * | |
3764 | * XXX illustrate | |
3765 | */ | |
a05e8c51 | 3766 | se->avg.last_update_time = cfs_rq->avg.last_update_time; |
f207934f PZ |
3767 | se->avg.period_contrib = cfs_rq->avg.period_contrib; |
3768 | ||
3769 | /* | |
3770 | * Hell(o) Nasty stuff.. we need to recompute _sum based on the new | |
3771 | * period_contrib. This isn't strictly correct, but since we're | |
3772 | * entirely outside of the PELT hierarchy, nobody cares if we truncate | |
3773 | * _sum a little. | |
3774 | */ | |
3775 | se->avg.util_sum = se->avg.util_avg * divider; | |
3776 | ||
3777 | se->avg.load_sum = divider; | |
3778 | if (se_weight(se)) { | |
3779 | se->avg.load_sum = | |
3780 | div_u64(se->avg.load_avg * se->avg.load_sum, se_weight(se)); | |
3781 | } | |
3782 | ||
3783 | se->avg.runnable_load_sum = se->avg.load_sum; | |
3784 | ||
8d5b9025 | 3785 | enqueue_load_avg(cfs_rq, se); |
a05e8c51 BP |
3786 | cfs_rq->avg.util_avg += se->avg.util_avg; |
3787 | cfs_rq->avg.util_sum += se->avg.util_sum; | |
0e2d2aaa PZ |
3788 | |
3789 | add_tg_cfs_propagate(cfs_rq, se->avg.load_sum); | |
a2c6c91f SM |
3790 | |
3791 | cfs_rq_util_change(cfs_rq); | |
a05e8c51 BP |
3792 | } |
3793 | ||
3d30544f PZ |
3794 | /** |
3795 | * detach_entity_load_avg - detach this entity from its cfs_rq load avg | |
3796 | * @cfs_rq: cfs_rq to detach from | |
3797 | * @se: sched_entity to detach | |
3798 | * | |
3799 | * Must call update_cfs_rq_load_avg() before this, since we rely on | |
3800 | * cfs_rq->avg.last_update_time being current. | |
3801 | */ | |
a05e8c51 BP |
3802 | static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) |
3803 | { | |
8d5b9025 | 3804 | dequeue_load_avg(cfs_rq, se); |
89741892 PZ |
3805 | sub_positive(&cfs_rq->avg.util_avg, se->avg.util_avg); |
3806 | sub_positive(&cfs_rq->avg.util_sum, se->avg.util_sum); | |
0e2d2aaa PZ |
3807 | |
3808 | add_tg_cfs_propagate(cfs_rq, -se->avg.load_sum); | |
a2c6c91f SM |
3809 | |
3810 | cfs_rq_util_change(cfs_rq); | |
a05e8c51 BP |
3811 | } |
3812 | ||
b382a531 PZ |
3813 | /* |
3814 | * Optional action to be done while updating the load average | |
3815 | */ | |
3816 | #define UPDATE_TG 0x1 | |
3817 | #define SKIP_AGE_LOAD 0x2 | |
3818 | #define DO_ATTACH 0x4 | |
3819 | ||
3820 | /* Update task and its cfs_rq load average */ | |
3821 | static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) | |
3822 | { | |
3823 | u64 now = cfs_rq_clock_task(cfs_rq); | |
3824 | struct rq *rq = rq_of(cfs_rq); | |
3825 | int cpu = cpu_of(rq); | |
3826 | int decayed; | |
3827 | ||
3828 | /* | |
3829 | * Track task load average for carrying it to new CPU after migrated, and | |
3830 | * track group sched_entity load average for task_h_load calc in migration | |
3831 | */ | |
3832 | if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD)) | |
3833 | __update_load_avg_se(now, cpu, cfs_rq, se); | |
3834 | ||
3835 | decayed = update_cfs_rq_load_avg(now, cfs_rq); | |
3836 | decayed |= propagate_entity_load_avg(se); | |
3837 | ||
3838 | if (!se->avg.last_update_time && (flags & DO_ATTACH)) { | |
3839 | ||
3840 | attach_entity_load_avg(cfs_rq, se); | |
3841 | update_tg_load_avg(cfs_rq, 0); | |
3842 | ||
3843 | } else if (decayed && (flags & UPDATE_TG)) | |
3844 | update_tg_load_avg(cfs_rq, 0); | |
3845 | } | |
3846 | ||
9d89c257 | 3847 | #ifndef CONFIG_64BIT |
0905f04e YD |
3848 | static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq) |
3849 | { | |
9d89c257 | 3850 | u64 last_update_time_copy; |
0905f04e | 3851 | u64 last_update_time; |
9ee474f5 | 3852 | |
9d89c257 YD |
3853 | do { |
3854 | last_update_time_copy = cfs_rq->load_last_update_time_copy; | |
3855 | smp_rmb(); | |
3856 | last_update_time = cfs_rq->avg.last_update_time; | |
3857 | } while (last_update_time != last_update_time_copy); | |
0905f04e YD |
3858 | |
3859 | return last_update_time; | |
3860 | } | |
9d89c257 | 3861 | #else |
0905f04e YD |
3862 | static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq) |
3863 | { | |
3864 | return cfs_rq->avg.last_update_time; | |
3865 | } | |
9d89c257 YD |
3866 | #endif |
3867 | ||
104cb16d MR |
3868 | /* |
3869 | * Synchronize entity load avg of dequeued entity without locking | |
3870 | * the previous rq. | |
3871 | */ | |
3872 | void sync_entity_load_avg(struct sched_entity *se) | |
3873 | { | |
3874 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
3875 | u64 last_update_time; | |
3876 | ||
3877 | last_update_time = cfs_rq_last_update_time(cfs_rq); | |
0ccb977f | 3878 | __update_load_avg_blocked_se(last_update_time, cpu_of(rq_of(cfs_rq)), se); |
104cb16d MR |
3879 | } |
3880 | ||
0905f04e YD |
3881 | /* |
3882 | * Task first catches up with cfs_rq, and then subtract | |
3883 | * itself from the cfs_rq (task must be off the queue now). | |
3884 | */ | |
3885 | void remove_entity_load_avg(struct sched_entity *se) | |
3886 | { | |
3887 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
2a2f5d4e | 3888 | unsigned long flags; |
0905f04e YD |
3889 | |
3890 | /* | |
7dc603c9 PZ |
3891 | * tasks cannot exit without having gone through wake_up_new_task() -> |
3892 | * post_init_entity_util_avg() which will have added things to the | |
3893 | * cfs_rq, so we can remove unconditionally. | |
3894 | * | |
3895 | * Similarly for groups, they will have passed through | |
3896 | * post_init_entity_util_avg() before unregister_sched_fair_group() | |
3897 | * calls this. | |
0905f04e | 3898 | */ |
0905f04e | 3899 | |
104cb16d | 3900 | sync_entity_load_avg(se); |
2a2f5d4e PZ |
3901 | |
3902 | raw_spin_lock_irqsave(&cfs_rq->removed.lock, flags); | |
3903 | ++cfs_rq->removed.nr; | |
3904 | cfs_rq->removed.util_avg += se->avg.util_avg; | |
3905 | cfs_rq->removed.load_avg += se->avg.load_avg; | |
0e2d2aaa | 3906 | cfs_rq->removed.runnable_sum += se->avg.load_sum; /* == runnable_sum */ |
2a2f5d4e | 3907 | raw_spin_unlock_irqrestore(&cfs_rq->removed.lock, flags); |
2dac754e | 3908 | } |
642dbc39 | 3909 | |
7ea241af YD |
3910 | static inline unsigned long cfs_rq_runnable_load_avg(struct cfs_rq *cfs_rq) |
3911 | { | |
1ea6c46a | 3912 | return cfs_rq->avg.runnable_load_avg; |
7ea241af YD |
3913 | } |
3914 | ||
3915 | static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq) | |
3916 | { | |
3917 | return cfs_rq->avg.load_avg; | |
3918 | } | |
3919 | ||
46f69fa3 | 3920 | static int idle_balance(struct rq *this_rq, struct rq_flags *rf); |
6e83125c | 3921 | |
38033c37 PZ |
3922 | #else /* CONFIG_SMP */ |
3923 | ||
01011473 | 3924 | static inline int |
3a123bbb | 3925 | update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) |
01011473 PZ |
3926 | { |
3927 | return 0; | |
3928 | } | |
3929 | ||
d31b1a66 VG |
3930 | #define UPDATE_TG 0x0 |
3931 | #define SKIP_AGE_LOAD 0x0 | |
b382a531 | 3932 | #define DO_ATTACH 0x0 |
d31b1a66 | 3933 | |
88c0616e | 3934 | static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int not_used1) |
536bd00c | 3935 | { |
88c0616e | 3936 | cfs_rq_util_change(cfs_rq); |
536bd00c RW |
3937 | } |
3938 | ||
9d89c257 | 3939 | static inline void remove_entity_load_avg(struct sched_entity *se) {} |
6e83125c | 3940 | |
a05e8c51 BP |
3941 | static inline void |
3942 | attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {} | |
3943 | static inline void | |
3944 | detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {} | |
3945 | ||
46f69fa3 | 3946 | static inline int idle_balance(struct rq *rq, struct rq_flags *rf) |
6e83125c PZ |
3947 | { |
3948 | return 0; | |
3949 | } | |
3950 | ||
38033c37 | 3951 | #endif /* CONFIG_SMP */ |
9d85f21c | 3952 | |
ddc97297 PZ |
3953 | static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se) |
3954 | { | |
3955 | #ifdef CONFIG_SCHED_DEBUG | |
3956 | s64 d = se->vruntime - cfs_rq->min_vruntime; | |
3957 | ||
3958 | if (d < 0) | |
3959 | d = -d; | |
3960 | ||
3961 | if (d > 3*sysctl_sched_latency) | |
ae92882e | 3962 | schedstat_inc(cfs_rq->nr_spread_over); |
ddc97297 PZ |
3963 | #endif |
3964 | } | |
3965 | ||
aeb73b04 PZ |
3966 | static void |
3967 | place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) | |
3968 | { | |
1af5f730 | 3969 | u64 vruntime = cfs_rq->min_vruntime; |
94dfb5e7 | 3970 | |
2cb8600e PZ |
3971 | /* |
3972 | * The 'current' period is already promised to the current tasks, | |
3973 | * however the extra weight of the new task will slow them down a | |
3974 | * little, place the new task so that it fits in the slot that | |
3975 | * stays open at the end. | |
3976 | */ | |
94dfb5e7 | 3977 | if (initial && sched_feat(START_DEBIT)) |
f9c0b095 | 3978 | vruntime += sched_vslice(cfs_rq, se); |
aeb73b04 | 3979 | |
a2e7a7eb | 3980 | /* sleeps up to a single latency don't count. */ |
5ca9880c | 3981 | if (!initial) { |
a2e7a7eb | 3982 | unsigned long thresh = sysctl_sched_latency; |
a7be37ac | 3983 | |
a2e7a7eb MG |
3984 | /* |
3985 | * Halve their sleep time's effect, to allow | |
3986 | * for a gentler effect of sleepers: | |
3987 | */ | |
3988 | if (sched_feat(GENTLE_FAIR_SLEEPERS)) | |
3989 | thresh >>= 1; | |
51e0304c | 3990 | |
a2e7a7eb | 3991 | vruntime -= thresh; |
aeb73b04 PZ |
3992 | } |
3993 | ||
b5d9d734 | 3994 | /* ensure we never gain time by being placed backwards. */ |
16c8f1c7 | 3995 | se->vruntime = max_vruntime(se->vruntime, vruntime); |
aeb73b04 PZ |
3996 | } |
3997 | ||
d3d9dc33 PT |
3998 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq); |
3999 | ||
cb251765 MG |
4000 | static inline void check_schedstat_required(void) |
4001 | { | |
4002 | #ifdef CONFIG_SCHEDSTATS | |
4003 | if (schedstat_enabled()) | |
4004 | return; | |
4005 | ||
4006 | /* Force schedstat enabled if a dependent tracepoint is active */ | |
4007 | if (trace_sched_stat_wait_enabled() || | |
4008 | trace_sched_stat_sleep_enabled() || | |
4009 | trace_sched_stat_iowait_enabled() || | |
4010 | trace_sched_stat_blocked_enabled() || | |
4011 | trace_sched_stat_runtime_enabled()) { | |
eda8dca5 | 4012 | printk_deferred_once("Scheduler tracepoints stat_sleep, stat_iowait, " |
cb251765 | 4013 | "stat_blocked and stat_runtime require the " |
f67abed5 | 4014 | "kernel parameter schedstats=enable or " |
cb251765 MG |
4015 | "kernel.sched_schedstats=1\n"); |
4016 | } | |
4017 | #endif | |
4018 | } | |
4019 | ||
b5179ac7 PZ |
4020 | |
4021 | /* | |
4022 | * MIGRATION | |
4023 | * | |
4024 | * dequeue | |
4025 | * update_curr() | |
4026 | * update_min_vruntime() | |
4027 | * vruntime -= min_vruntime | |
4028 | * | |
4029 | * enqueue | |
4030 | * update_curr() | |
4031 | * update_min_vruntime() | |
4032 | * vruntime += min_vruntime | |
4033 | * | |
4034 | * this way the vruntime transition between RQs is done when both | |
4035 | * min_vruntime are up-to-date. | |
4036 | * | |
4037 | * WAKEUP (remote) | |
4038 | * | |
59efa0ba | 4039 | * ->migrate_task_rq_fair() (p->state == TASK_WAKING) |
b5179ac7 PZ |
4040 | * vruntime -= min_vruntime |
4041 | * | |
4042 | * enqueue | |
4043 | * update_curr() | |
4044 | * update_min_vruntime() | |
4045 | * vruntime += min_vruntime | |
4046 | * | |
4047 | * this way we don't have the most up-to-date min_vruntime on the originating | |
4048 | * CPU and an up-to-date min_vruntime on the destination CPU. | |
4049 | */ | |
4050 | ||
bf0f6f24 | 4051 | static void |
88ec22d3 | 4052 | enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 4053 | { |
2f950354 PZ |
4054 | bool renorm = !(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_MIGRATED); |
4055 | bool curr = cfs_rq->curr == se; | |
4056 | ||
88ec22d3 | 4057 | /* |
2f950354 PZ |
4058 | * If we're the current task, we must renormalise before calling |
4059 | * update_curr(). | |
88ec22d3 | 4060 | */ |
2f950354 | 4061 | if (renorm && curr) |
88ec22d3 PZ |
4062 | se->vruntime += cfs_rq->min_vruntime; |
4063 | ||
2f950354 PZ |
4064 | update_curr(cfs_rq); |
4065 | ||
bf0f6f24 | 4066 | /* |
2f950354 PZ |
4067 | * Otherwise, renormalise after, such that we're placed at the current |
4068 | * moment in time, instead of some random moment in the past. Being | |
4069 | * placed in the past could significantly boost this task to the | |
4070 | * fairness detriment of existing tasks. | |
bf0f6f24 | 4071 | */ |
2f950354 PZ |
4072 | if (renorm && !curr) |
4073 | se->vruntime += cfs_rq->min_vruntime; | |
4074 | ||
89ee048f VG |
4075 | /* |
4076 | * When enqueuing a sched_entity, we must: | |
4077 | * - Update loads to have both entity and cfs_rq synced with now. | |
4078 | * - Add its load to cfs_rq->runnable_avg | |
4079 | * - For group_entity, update its weight to reflect the new share of | |
4080 | * its group cfs_rq | |
4081 | * - Add its new weight to cfs_rq->load.weight | |
4082 | */ | |
b382a531 | 4083 | update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH); |
1ea6c46a | 4084 | update_cfs_group(se); |
b5b3e35f | 4085 | enqueue_runnable_load_avg(cfs_rq, se); |
17bc14b7 | 4086 | account_entity_enqueue(cfs_rq, se); |
bf0f6f24 | 4087 | |
1a3d027c | 4088 | if (flags & ENQUEUE_WAKEUP) |
aeb73b04 | 4089 | place_entity(cfs_rq, se, 0); |
bf0f6f24 | 4090 | |
cb251765 | 4091 | check_schedstat_required(); |
4fa8d299 JP |
4092 | update_stats_enqueue(cfs_rq, se, flags); |
4093 | check_spread(cfs_rq, se); | |
2f950354 | 4094 | if (!curr) |
83b699ed | 4095 | __enqueue_entity(cfs_rq, se); |
2069dd75 | 4096 | se->on_rq = 1; |
3d4b47b4 | 4097 | |
d3d9dc33 | 4098 | if (cfs_rq->nr_running == 1) { |
3d4b47b4 | 4099 | list_add_leaf_cfs_rq(cfs_rq); |
d3d9dc33 PT |
4100 | check_enqueue_throttle(cfs_rq); |
4101 | } | |
bf0f6f24 IM |
4102 | } |
4103 | ||
2c13c919 | 4104 | static void __clear_buddies_last(struct sched_entity *se) |
2002c695 | 4105 | { |
2c13c919 RR |
4106 | for_each_sched_entity(se) { |
4107 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 4108 | if (cfs_rq->last != se) |
2c13c919 | 4109 | break; |
f1044799 PZ |
4110 | |
4111 | cfs_rq->last = NULL; | |
2c13c919 RR |
4112 | } |
4113 | } | |
2002c695 | 4114 | |
2c13c919 RR |
4115 | static void __clear_buddies_next(struct sched_entity *se) |
4116 | { | |
4117 | for_each_sched_entity(se) { | |
4118 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 4119 | if (cfs_rq->next != se) |
2c13c919 | 4120 | break; |
f1044799 PZ |
4121 | |
4122 | cfs_rq->next = NULL; | |
2c13c919 | 4123 | } |
2002c695 PZ |
4124 | } |
4125 | ||
ac53db59 RR |
4126 | static void __clear_buddies_skip(struct sched_entity *se) |
4127 | { | |
4128 | for_each_sched_entity(se) { | |
4129 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 4130 | if (cfs_rq->skip != se) |
ac53db59 | 4131 | break; |
f1044799 PZ |
4132 | |
4133 | cfs_rq->skip = NULL; | |
ac53db59 RR |
4134 | } |
4135 | } | |
4136 | ||
a571bbea PZ |
4137 | static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) |
4138 | { | |
2c13c919 RR |
4139 | if (cfs_rq->last == se) |
4140 | __clear_buddies_last(se); | |
4141 | ||
4142 | if (cfs_rq->next == se) | |
4143 | __clear_buddies_next(se); | |
ac53db59 RR |
4144 | |
4145 | if (cfs_rq->skip == se) | |
4146 | __clear_buddies_skip(se); | |
a571bbea PZ |
4147 | } |
4148 | ||
6c16a6dc | 4149 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
d8b4986d | 4150 | |
bf0f6f24 | 4151 | static void |
371fd7e7 | 4152 | dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 4153 | { |
a2a2d680 DA |
4154 | /* |
4155 | * Update run-time statistics of the 'current'. | |
4156 | */ | |
4157 | update_curr(cfs_rq); | |
89ee048f VG |
4158 | |
4159 | /* | |
4160 | * When dequeuing a sched_entity, we must: | |
4161 | * - Update loads to have both entity and cfs_rq synced with now. | |
4162 | * - Substract its load from the cfs_rq->runnable_avg. | |
4163 | * - Substract its previous weight from cfs_rq->load.weight. | |
4164 | * - For group entity, update its weight to reflect the new share | |
4165 | * of its group cfs_rq. | |
4166 | */ | |
88c0616e | 4167 | update_load_avg(cfs_rq, se, UPDATE_TG); |
b5b3e35f | 4168 | dequeue_runnable_load_avg(cfs_rq, se); |
a2a2d680 | 4169 | |
4fa8d299 | 4170 | update_stats_dequeue(cfs_rq, se, flags); |
67e9fb2a | 4171 | |
2002c695 | 4172 | clear_buddies(cfs_rq, se); |
4793241b | 4173 | |
83b699ed | 4174 | if (se != cfs_rq->curr) |
30cfdcfc | 4175 | __dequeue_entity(cfs_rq, se); |
17bc14b7 | 4176 | se->on_rq = 0; |
30cfdcfc | 4177 | account_entity_dequeue(cfs_rq, se); |
88ec22d3 PZ |
4178 | |
4179 | /* | |
b60205c7 PZ |
4180 | * Normalize after update_curr(); which will also have moved |
4181 | * min_vruntime if @se is the one holding it back. But before doing | |
4182 | * update_min_vruntime() again, which will discount @se's position and | |
4183 | * can move min_vruntime forward still more. | |
88ec22d3 | 4184 | */ |
371fd7e7 | 4185 | if (!(flags & DEQUEUE_SLEEP)) |
88ec22d3 | 4186 | se->vruntime -= cfs_rq->min_vruntime; |
1e876231 | 4187 | |
d8b4986d PT |
4188 | /* return excess runtime on last dequeue */ |
4189 | return_cfs_rq_runtime(cfs_rq); | |
4190 | ||
1ea6c46a | 4191 | update_cfs_group(se); |
b60205c7 PZ |
4192 | |
4193 | /* | |
4194 | * Now advance min_vruntime if @se was the entity holding it back, | |
4195 | * except when: DEQUEUE_SAVE && !DEQUEUE_MOVE, in this case we'll be | |
4196 | * put back on, and if we advance min_vruntime, we'll be placed back | |
4197 | * further than we started -- ie. we'll be penalized. | |
4198 | */ | |
e9232516 | 4199 | if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) != DEQUEUE_SAVE) |
b60205c7 | 4200 | update_min_vruntime(cfs_rq); |
bf0f6f24 IM |
4201 | } |
4202 | ||
4203 | /* | |
4204 | * Preempt the current task with a newly woken task if needed: | |
4205 | */ | |
7c92e54f | 4206 | static void |
2e09bf55 | 4207 | check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
bf0f6f24 | 4208 | { |
11697830 | 4209 | unsigned long ideal_runtime, delta_exec; |
f4cfb33e WX |
4210 | struct sched_entity *se; |
4211 | s64 delta; | |
11697830 | 4212 | |
6d0f0ebd | 4213 | ideal_runtime = sched_slice(cfs_rq, curr); |
11697830 | 4214 | delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; |
a9f3e2b5 | 4215 | if (delta_exec > ideal_runtime) { |
8875125e | 4216 | resched_curr(rq_of(cfs_rq)); |
a9f3e2b5 MG |
4217 | /* |
4218 | * The current task ran long enough, ensure it doesn't get | |
4219 | * re-elected due to buddy favours. | |
4220 | */ | |
4221 | clear_buddies(cfs_rq, curr); | |
f685ceac MG |
4222 | return; |
4223 | } | |
4224 | ||
4225 | /* | |
4226 | * Ensure that a task that missed wakeup preemption by a | |
4227 | * narrow margin doesn't have to wait for a full slice. | |
4228 | * This also mitigates buddy induced latencies under load. | |
4229 | */ | |
f685ceac MG |
4230 | if (delta_exec < sysctl_sched_min_granularity) |
4231 | return; | |
4232 | ||
f4cfb33e WX |
4233 | se = __pick_first_entity(cfs_rq); |
4234 | delta = curr->vruntime - se->vruntime; | |
f685ceac | 4235 | |
f4cfb33e WX |
4236 | if (delta < 0) |
4237 | return; | |
d7d82944 | 4238 | |
f4cfb33e | 4239 | if (delta > ideal_runtime) |
8875125e | 4240 | resched_curr(rq_of(cfs_rq)); |
bf0f6f24 IM |
4241 | } |
4242 | ||
83b699ed | 4243 | static void |
8494f412 | 4244 | set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 4245 | { |
83b699ed SV |
4246 | /* 'current' is not kept within the tree. */ |
4247 | if (se->on_rq) { | |
4248 | /* | |
4249 | * Any task has to be enqueued before it get to execute on | |
4250 | * a CPU. So account for the time it spent waiting on the | |
4251 | * runqueue. | |
4252 | */ | |
4fa8d299 | 4253 | update_stats_wait_end(cfs_rq, se); |
83b699ed | 4254 | __dequeue_entity(cfs_rq, se); |
88c0616e | 4255 | update_load_avg(cfs_rq, se, UPDATE_TG); |
83b699ed SV |
4256 | } |
4257 | ||
79303e9e | 4258 | update_stats_curr_start(cfs_rq, se); |
429d43bc | 4259 | cfs_rq->curr = se; |
4fa8d299 | 4260 | |
eba1ed4b IM |
4261 | /* |
4262 | * Track our maximum slice length, if the CPU's load is at | |
4263 | * least twice that of our own weight (i.e. dont track it | |
4264 | * when there are only lesser-weight tasks around): | |
4265 | */ | |
cb251765 | 4266 | if (schedstat_enabled() && rq_of(cfs_rq)->load.weight >= 2*se->load.weight) { |
4fa8d299 JP |
4267 | schedstat_set(se->statistics.slice_max, |
4268 | max((u64)schedstat_val(se->statistics.slice_max), | |
4269 | se->sum_exec_runtime - se->prev_sum_exec_runtime)); | |
eba1ed4b | 4270 | } |
4fa8d299 | 4271 | |
4a55b450 | 4272 | se->prev_sum_exec_runtime = se->sum_exec_runtime; |
bf0f6f24 IM |
4273 | } |
4274 | ||
3f3a4904 PZ |
4275 | static int |
4276 | wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se); | |
4277 | ||
ac53db59 RR |
4278 | /* |
4279 | * Pick the next process, keeping these things in mind, in this order: | |
4280 | * 1) keep things fair between processes/task groups | |
4281 | * 2) pick the "next" process, since someone really wants that to run | |
4282 | * 3) pick the "last" process, for cache locality | |
4283 | * 4) do not run the "skip" process, if something else is available | |
4284 | */ | |
678d5718 PZ |
4285 | static struct sched_entity * |
4286 | pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) | |
aa2ac252 | 4287 | { |
678d5718 PZ |
4288 | struct sched_entity *left = __pick_first_entity(cfs_rq); |
4289 | struct sched_entity *se; | |
4290 | ||
4291 | /* | |
4292 | * If curr is set we have to see if its left of the leftmost entity | |
4293 | * still in the tree, provided there was anything in the tree at all. | |
4294 | */ | |
4295 | if (!left || (curr && entity_before(curr, left))) | |
4296 | left = curr; | |
4297 | ||
4298 | se = left; /* ideally we run the leftmost entity */ | |
f4b6755f | 4299 | |
ac53db59 RR |
4300 | /* |
4301 | * Avoid running the skip buddy, if running something else can | |
4302 | * be done without getting too unfair. | |
4303 | */ | |
4304 | if (cfs_rq->skip == se) { | |
678d5718 PZ |
4305 | struct sched_entity *second; |
4306 | ||
4307 | if (se == curr) { | |
4308 | second = __pick_first_entity(cfs_rq); | |
4309 | } else { | |
4310 | second = __pick_next_entity(se); | |
4311 | if (!second || (curr && entity_before(curr, second))) | |
4312 | second = curr; | |
4313 | } | |
4314 | ||
ac53db59 RR |
4315 | if (second && wakeup_preempt_entity(second, left) < 1) |
4316 | se = second; | |
4317 | } | |
aa2ac252 | 4318 | |
f685ceac MG |
4319 | /* |
4320 | * Prefer last buddy, try to return the CPU to a preempted task. | |
4321 | */ | |
4322 | if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) | |
4323 | se = cfs_rq->last; | |
4324 | ||
ac53db59 RR |
4325 | /* |
4326 | * Someone really wants this to run. If it's not unfair, run it. | |
4327 | */ | |
4328 | if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) | |
4329 | se = cfs_rq->next; | |
4330 | ||
f685ceac | 4331 | clear_buddies(cfs_rq, se); |
4793241b PZ |
4332 | |
4333 | return se; | |
aa2ac252 PZ |
4334 | } |
4335 | ||
678d5718 | 4336 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
d3d9dc33 | 4337 | |
ab6cde26 | 4338 | static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) |
bf0f6f24 IM |
4339 | { |
4340 | /* | |
4341 | * If still on the runqueue then deactivate_task() | |
4342 | * was not called and update_curr() has to be done: | |
4343 | */ | |
4344 | if (prev->on_rq) | |
b7cc0896 | 4345 | update_curr(cfs_rq); |
bf0f6f24 | 4346 | |
d3d9dc33 PT |
4347 | /* throttle cfs_rqs exceeding runtime */ |
4348 | check_cfs_rq_runtime(cfs_rq); | |
4349 | ||
4fa8d299 | 4350 | check_spread(cfs_rq, prev); |
cb251765 | 4351 | |
30cfdcfc | 4352 | if (prev->on_rq) { |
4fa8d299 | 4353 | update_stats_wait_start(cfs_rq, prev); |
30cfdcfc DA |
4354 | /* Put 'current' back into the tree. */ |
4355 | __enqueue_entity(cfs_rq, prev); | |
9d85f21c | 4356 | /* in !on_rq case, update occurred at dequeue */ |
88c0616e | 4357 | update_load_avg(cfs_rq, prev, 0); |
30cfdcfc | 4358 | } |
429d43bc | 4359 | cfs_rq->curr = NULL; |
bf0f6f24 IM |
4360 | } |
4361 | ||
8f4d37ec PZ |
4362 | static void |
4363 | entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) | |
bf0f6f24 | 4364 | { |
bf0f6f24 | 4365 | /* |
30cfdcfc | 4366 | * Update run-time statistics of the 'current'. |
bf0f6f24 | 4367 | */ |
30cfdcfc | 4368 | update_curr(cfs_rq); |
bf0f6f24 | 4369 | |
9d85f21c PT |
4370 | /* |
4371 | * Ensure that runnable average is periodically updated. | |
4372 | */ | |
88c0616e | 4373 | update_load_avg(cfs_rq, curr, UPDATE_TG); |
1ea6c46a | 4374 | update_cfs_group(curr); |
9d85f21c | 4375 | |
8f4d37ec PZ |
4376 | #ifdef CONFIG_SCHED_HRTICK |
4377 | /* | |
4378 | * queued ticks are scheduled to match the slice, so don't bother | |
4379 | * validating it and just reschedule. | |
4380 | */ | |
983ed7a6 | 4381 | if (queued) { |
8875125e | 4382 | resched_curr(rq_of(cfs_rq)); |
983ed7a6 HH |
4383 | return; |
4384 | } | |
8f4d37ec PZ |
4385 | /* |
4386 | * don't let the period tick interfere with the hrtick preemption | |
4387 | */ | |
4388 | if (!sched_feat(DOUBLE_TICK) && | |
4389 | hrtimer_active(&rq_of(cfs_rq)->hrtick_timer)) | |
4390 | return; | |
4391 | #endif | |
4392 | ||
2c2efaed | 4393 | if (cfs_rq->nr_running > 1) |
2e09bf55 | 4394 | check_preempt_tick(cfs_rq, curr); |
bf0f6f24 IM |
4395 | } |
4396 | ||
ab84d31e PT |
4397 | |
4398 | /************************************************** | |
4399 | * CFS bandwidth control machinery | |
4400 | */ | |
4401 | ||
4402 | #ifdef CONFIG_CFS_BANDWIDTH | |
029632fb PZ |
4403 | |
4404 | #ifdef HAVE_JUMP_LABEL | |
c5905afb | 4405 | static struct static_key __cfs_bandwidth_used; |
029632fb PZ |
4406 | |
4407 | static inline bool cfs_bandwidth_used(void) | |
4408 | { | |
c5905afb | 4409 | return static_key_false(&__cfs_bandwidth_used); |
029632fb PZ |
4410 | } |
4411 | ||
1ee14e6c | 4412 | void cfs_bandwidth_usage_inc(void) |
029632fb | 4413 | { |
ce48c146 | 4414 | static_key_slow_inc_cpuslocked(&__cfs_bandwidth_used); |
1ee14e6c BS |
4415 | } |
4416 | ||
4417 | void cfs_bandwidth_usage_dec(void) | |
4418 | { | |
ce48c146 | 4419 | static_key_slow_dec_cpuslocked(&__cfs_bandwidth_used); |
029632fb PZ |
4420 | } |
4421 | #else /* HAVE_JUMP_LABEL */ | |
4422 | static bool cfs_bandwidth_used(void) | |
4423 | { | |
4424 | return true; | |
4425 | } | |
4426 | ||
1ee14e6c BS |
4427 | void cfs_bandwidth_usage_inc(void) {} |
4428 | void cfs_bandwidth_usage_dec(void) {} | |
029632fb PZ |
4429 | #endif /* HAVE_JUMP_LABEL */ |
4430 | ||
ab84d31e PT |
4431 | /* |
4432 | * default period for cfs group bandwidth. | |
4433 | * default: 0.1s, units: nanoseconds | |
4434 | */ | |
4435 | static inline u64 default_cfs_period(void) | |
4436 | { | |
4437 | return 100000000ULL; | |
4438 | } | |
ec12cb7f PT |
4439 | |
4440 | static inline u64 sched_cfs_bandwidth_slice(void) | |
4441 | { | |
4442 | return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC; | |
4443 | } | |
4444 | ||
a9cf55b2 | 4445 | /* |
e057fc62 QC |
4446 | * Replenish runtime according to assigned quota. We use sched_clock_cpu |
4447 | * directly instead of rq->clock to avoid adding additional synchronization | |
4448 | * around rq->lock. | |
a9cf55b2 PT |
4449 | * |
4450 | * requires cfs_b->lock | |
4451 | */ | |
029632fb | 4452 | void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b) |
a9cf55b2 | 4453 | { |
e057fc62 QC |
4454 | if (cfs_b->quota != RUNTIME_INF) |
4455 | cfs_b->runtime = cfs_b->quota; | |
a9cf55b2 PT |
4456 | } |
4457 | ||
029632fb PZ |
4458 | static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
4459 | { | |
4460 | return &tg->cfs_bandwidth; | |
4461 | } | |
4462 | ||
f1b17280 PT |
4463 | /* rq->task_clock normalized against any time this cfs_rq has spent throttled */ |
4464 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) | |
4465 | { | |
4466 | if (unlikely(cfs_rq->throttle_count)) | |
1a99ae3f | 4467 | return cfs_rq->throttled_clock_task - cfs_rq->throttled_clock_task_time; |
f1b17280 | 4468 | |
78becc27 | 4469 | return rq_clock_task(rq_of(cfs_rq)) - cfs_rq->throttled_clock_task_time; |
f1b17280 PT |
4470 | } |
4471 | ||
85dac906 PT |
4472 | /* returns 0 on failure to allocate runtime */ |
4473 | static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
ec12cb7f PT |
4474 | { |
4475 | struct task_group *tg = cfs_rq->tg; | |
4476 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg); | |
aadd794e | 4477 | u64 amount = 0, min_amount; |
ec12cb7f PT |
4478 | |
4479 | /* note: this is a positive sum as runtime_remaining <= 0 */ | |
4480 | min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining; | |
4481 | ||
4482 | raw_spin_lock(&cfs_b->lock); | |
4483 | if (cfs_b->quota == RUNTIME_INF) | |
4484 | amount = min_amount; | |
58088ad0 | 4485 | else { |
77a4d1a1 | 4486 | start_cfs_bandwidth(cfs_b); |
58088ad0 PT |
4487 | |
4488 | if (cfs_b->runtime > 0) { | |
4489 | amount = min(cfs_b->runtime, min_amount); | |
4490 | cfs_b->runtime -= amount; | |
4491 | cfs_b->idle = 0; | |
4492 | } | |
ec12cb7f PT |
4493 | } |
4494 | raw_spin_unlock(&cfs_b->lock); | |
4495 | ||
4496 | cfs_rq->runtime_remaining += amount; | |
85dac906 PT |
4497 | |
4498 | return cfs_rq->runtime_remaining > 0; | |
ec12cb7f PT |
4499 | } |
4500 | ||
9dbdb155 | 4501 | static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
a9cf55b2 PT |
4502 | { |
4503 | /* dock delta_exec before expiring quota (as it could span periods) */ | |
ec12cb7f | 4504 | cfs_rq->runtime_remaining -= delta_exec; |
a9cf55b2 PT |
4505 | |
4506 | if (likely(cfs_rq->runtime_remaining > 0)) | |
ec12cb7f PT |
4507 | return; |
4508 | ||
62841e21 L |
4509 | if (cfs_rq->throttled) |
4510 | return; | |
85dac906 PT |
4511 | /* |
4512 | * if we're unable to extend our runtime we resched so that the active | |
4513 | * hierarchy can be throttled | |
4514 | */ | |
4515 | if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr)) | |
8875125e | 4516 | resched_curr(rq_of(cfs_rq)); |
ec12cb7f PT |
4517 | } |
4518 | ||
6c16a6dc | 4519 | static __always_inline |
9dbdb155 | 4520 | void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
ec12cb7f | 4521 | { |
56f570e5 | 4522 | if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled) |
ec12cb7f PT |
4523 | return; |
4524 | ||
4525 | __account_cfs_rq_runtime(cfs_rq, delta_exec); | |
4526 | } | |
4527 | ||
85dac906 PT |
4528 | static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) |
4529 | { | |
56f570e5 | 4530 | return cfs_bandwidth_used() && cfs_rq->throttled; |
85dac906 PT |
4531 | } |
4532 | ||
64660c86 PT |
4533 | /* check whether cfs_rq, or any parent, is throttled */ |
4534 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) | |
4535 | { | |
56f570e5 | 4536 | return cfs_bandwidth_used() && cfs_rq->throttle_count; |
64660c86 PT |
4537 | } |
4538 | ||
4539 | /* | |
4540 | * Ensure that neither of the group entities corresponding to src_cpu or | |
4541 | * dest_cpu are members of a throttled hierarchy when performing group | |
4542 | * load-balance operations. | |
4543 | */ | |
4544 | static inline int throttled_lb_pair(struct task_group *tg, | |
4545 | int src_cpu, int dest_cpu) | |
4546 | { | |
4547 | struct cfs_rq *src_cfs_rq, *dest_cfs_rq; | |
4548 | ||
4549 | src_cfs_rq = tg->cfs_rq[src_cpu]; | |
4550 | dest_cfs_rq = tg->cfs_rq[dest_cpu]; | |
4551 | ||
4552 | return throttled_hierarchy(src_cfs_rq) || | |
4553 | throttled_hierarchy(dest_cfs_rq); | |
4554 | } | |
4555 | ||
4556 | /* updated child weight may affect parent so we have to do this bottom up */ | |
4557 | static int tg_unthrottle_up(struct task_group *tg, void *data) | |
4558 | { | |
4559 | struct rq *rq = data; | |
4560 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; | |
4561 | ||
4562 | cfs_rq->throttle_count--; | |
64660c86 | 4563 | if (!cfs_rq->throttle_count) { |
f1b17280 | 4564 | /* adjust cfs_rq_clock_task() */ |
78becc27 | 4565 | cfs_rq->throttled_clock_task_time += rq_clock_task(rq) - |
f1b17280 | 4566 | cfs_rq->throttled_clock_task; |
64660c86 | 4567 | } |
64660c86 PT |
4568 | |
4569 | return 0; | |
4570 | } | |
4571 | ||
4572 | static int tg_throttle_down(struct task_group *tg, void *data) | |
4573 | { | |
4574 | struct rq *rq = data; | |
4575 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; | |
4576 | ||
82958366 PT |
4577 | /* group is entering throttled state, stop time */ |
4578 | if (!cfs_rq->throttle_count) | |
78becc27 | 4579 | cfs_rq->throttled_clock_task = rq_clock_task(rq); |
64660c86 PT |
4580 | cfs_rq->throttle_count++; |
4581 | ||
4582 | return 0; | |
4583 | } | |
4584 | ||
d3d9dc33 | 4585 | static void throttle_cfs_rq(struct cfs_rq *cfs_rq) |
85dac906 PT |
4586 | { |
4587 | struct rq *rq = rq_of(cfs_rq); | |
4588 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
4589 | struct sched_entity *se; | |
4590 | long task_delta, dequeue = 1; | |
77a4d1a1 | 4591 | bool empty; |
85dac906 PT |
4592 | |
4593 | se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; | |
4594 | ||
f1b17280 | 4595 | /* freeze hierarchy runnable averages while throttled */ |
64660c86 PT |
4596 | rcu_read_lock(); |
4597 | walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq); | |
4598 | rcu_read_unlock(); | |
85dac906 PT |
4599 | |
4600 | task_delta = cfs_rq->h_nr_running; | |
4601 | for_each_sched_entity(se) { | |
4602 | struct cfs_rq *qcfs_rq = cfs_rq_of(se); | |
4603 | /* throttled entity or throttle-on-deactivate */ | |
4604 | if (!se->on_rq) | |
4605 | break; | |
4606 | ||
4607 | if (dequeue) | |
4608 | dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP); | |
4609 | qcfs_rq->h_nr_running -= task_delta; | |
4610 | ||
4611 | if (qcfs_rq->load.weight) | |
4612 | dequeue = 0; | |
4613 | } | |
4614 | ||
4615 | if (!se) | |
72465447 | 4616 | sub_nr_running(rq, task_delta); |
85dac906 PT |
4617 | |
4618 | cfs_rq->throttled = 1; | |
78becc27 | 4619 | cfs_rq->throttled_clock = rq_clock(rq); |
85dac906 | 4620 | raw_spin_lock(&cfs_b->lock); |
d49db342 | 4621 | empty = list_empty(&cfs_b->throttled_cfs_rq); |
77a4d1a1 | 4622 | |
c06f04c7 BS |
4623 | /* |
4624 | * Add to the _head_ of the list, so that an already-started | |
3f7aa147 PA |
4625 | * distribute_cfs_runtime will not see us. If disribute_cfs_runtime is |
4626 | * not running add to the tail so that later runqueues don't get starved. | |
c06f04c7 | 4627 | */ |
3f7aa147 PA |
4628 | if (cfs_b->distribute_running) |
4629 | list_add_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq); | |
4630 | else | |
4631 | list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq); | |
77a4d1a1 PZ |
4632 | |
4633 | /* | |
4634 | * If we're the first throttled task, make sure the bandwidth | |
4635 | * timer is running. | |
4636 | */ | |
4637 | if (empty) | |
4638 | start_cfs_bandwidth(cfs_b); | |
4639 | ||
85dac906 PT |
4640 | raw_spin_unlock(&cfs_b->lock); |
4641 | } | |
4642 | ||
029632fb | 4643 | void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) |
671fd9da PT |
4644 | { |
4645 | struct rq *rq = rq_of(cfs_rq); | |
4646 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
4647 | struct sched_entity *se; | |
4648 | int enqueue = 1; | |
4649 | long task_delta; | |
4650 | ||
22b958d8 | 4651 | se = cfs_rq->tg->se[cpu_of(rq)]; |
671fd9da PT |
4652 | |
4653 | cfs_rq->throttled = 0; | |
1a55af2e FW |
4654 | |
4655 | update_rq_clock(rq); | |
4656 | ||
671fd9da | 4657 | raw_spin_lock(&cfs_b->lock); |
78becc27 | 4658 | cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock; |
671fd9da PT |
4659 | list_del_rcu(&cfs_rq->throttled_list); |
4660 | raw_spin_unlock(&cfs_b->lock); | |
4661 | ||
64660c86 PT |
4662 | /* update hierarchical throttle state */ |
4663 | walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq); | |
4664 | ||
671fd9da PT |
4665 | if (!cfs_rq->load.weight) |
4666 | return; | |
4667 | ||
4668 | task_delta = cfs_rq->h_nr_running; | |
4669 | for_each_sched_entity(se) { | |
4670 | if (se->on_rq) | |
4671 | enqueue = 0; | |
4672 | ||
4673 | cfs_rq = cfs_rq_of(se); | |
4674 | if (enqueue) | |
4675 | enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP); | |
4676 | cfs_rq->h_nr_running += task_delta; | |
4677 | ||
4678 | if (cfs_rq_throttled(cfs_rq)) | |
4679 | break; | |
4680 | } | |
4681 | ||
4682 | if (!se) | |
72465447 | 4683 | add_nr_running(rq, task_delta); |
671fd9da PT |
4684 | |
4685 | /* determine whether we need to wake up potentially idle cpu */ | |
4686 | if (rq->curr == rq->idle && rq->cfs.nr_running) | |
8875125e | 4687 | resched_curr(rq); |
671fd9da PT |
4688 | } |
4689 | ||
aadd794e | 4690 | static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, u64 remaining) |
671fd9da PT |
4691 | { |
4692 | struct cfs_rq *cfs_rq; | |
c06f04c7 BS |
4693 | u64 runtime; |
4694 | u64 starting_runtime = remaining; | |
671fd9da PT |
4695 | |
4696 | rcu_read_lock(); | |
4697 | list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq, | |
4698 | throttled_list) { | |
4699 | struct rq *rq = rq_of(cfs_rq); | |
8a8c69c3 | 4700 | struct rq_flags rf; |
671fd9da | 4701 | |
8a8c69c3 | 4702 | rq_lock(rq, &rf); |
671fd9da PT |
4703 | if (!cfs_rq_throttled(cfs_rq)) |
4704 | goto next; | |
4705 | ||
62841e21 L |
4706 | /* By the above check, this should never be true */ |
4707 | SCHED_WARN_ON(cfs_rq->runtime_remaining > 0); | |
4708 | ||
671fd9da PT |
4709 | runtime = -cfs_rq->runtime_remaining + 1; |
4710 | if (runtime > remaining) | |
4711 | runtime = remaining; | |
4712 | remaining -= runtime; | |
4713 | ||
4714 | cfs_rq->runtime_remaining += runtime; | |
671fd9da PT |
4715 | |
4716 | /* we check whether we're throttled above */ | |
4717 | if (cfs_rq->runtime_remaining > 0) | |
4718 | unthrottle_cfs_rq(cfs_rq); | |
4719 | ||
4720 | next: | |
8a8c69c3 | 4721 | rq_unlock(rq, &rf); |
671fd9da PT |
4722 | |
4723 | if (!remaining) | |
4724 | break; | |
4725 | } | |
4726 | rcu_read_unlock(); | |
4727 | ||
c06f04c7 | 4728 | return starting_runtime - remaining; |
671fd9da PT |
4729 | } |
4730 | ||
58088ad0 PT |
4731 | /* |
4732 | * Responsible for refilling a task_group's bandwidth and unthrottling its | |
4733 | * cfs_rqs as appropriate. If there has been no activity within the last | |
4734 | * period the timer is deactivated until scheduling resumes; cfs_b->idle is | |
4735 | * used to track this state. | |
4736 | */ | |
4737 | static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) | |
4738 | { | |
aadd794e | 4739 | u64 runtime; |
51f2176d | 4740 | int throttled; |
58088ad0 | 4741 | |
58088ad0 PT |
4742 | /* no need to continue the timer with no bandwidth constraint */ |
4743 | if (cfs_b->quota == RUNTIME_INF) | |
51f2176d | 4744 | goto out_deactivate; |
58088ad0 | 4745 | |
671fd9da | 4746 | throttled = !list_empty(&cfs_b->throttled_cfs_rq); |
e8da1b18 | 4747 | cfs_b->nr_periods += overrun; |
671fd9da | 4748 | |
51f2176d BS |
4749 | /* |
4750 | * idle depends on !throttled (for the case of a large deficit), and if | |
4751 | * we're going inactive then everything else can be deferred | |
4752 | */ | |
4753 | if (cfs_b->idle && !throttled) | |
4754 | goto out_deactivate; | |
a9cf55b2 PT |
4755 | |
4756 | __refill_cfs_bandwidth_runtime(cfs_b); | |
4757 | ||
671fd9da PT |
4758 | if (!throttled) { |
4759 | /* mark as potentially idle for the upcoming period */ | |
4760 | cfs_b->idle = 1; | |
51f2176d | 4761 | return 0; |
671fd9da PT |
4762 | } |
4763 | ||
e8da1b18 NR |
4764 | /* account preceding periods in which throttling occurred */ |
4765 | cfs_b->nr_throttled += overrun; | |
4766 | ||
671fd9da | 4767 | /* |
c06f04c7 BS |
4768 | * This check is repeated as we are holding onto the new bandwidth while |
4769 | * we unthrottle. This can potentially race with an unthrottled group | |
4770 | * trying to acquire new bandwidth from the global pool. This can result | |
4771 | * in us over-using our runtime if it is all used during this loop, but | |
4772 | * only by limited amounts in that extreme case. | |
671fd9da | 4773 | */ |
3f7aa147 | 4774 | while (throttled && cfs_b->runtime > 0 && !cfs_b->distribute_running) { |
c06f04c7 | 4775 | runtime = cfs_b->runtime; |
3f7aa147 | 4776 | cfs_b->distribute_running = 1; |
671fd9da PT |
4777 | raw_spin_unlock(&cfs_b->lock); |
4778 | /* we can't nest cfs_b->lock while distributing bandwidth */ | |
aadd794e | 4779 | runtime = distribute_cfs_runtime(cfs_b, runtime); |
671fd9da PT |
4780 | raw_spin_lock(&cfs_b->lock); |
4781 | ||
3f7aa147 | 4782 | cfs_b->distribute_running = 0; |
671fd9da | 4783 | throttled = !list_empty(&cfs_b->throttled_cfs_rq); |
c06f04c7 | 4784 | |
834ef3c9 | 4785 | lsub_positive(&cfs_b->runtime, runtime); |
671fd9da | 4786 | } |
58088ad0 | 4787 | |
671fd9da PT |
4788 | /* |
4789 | * While we are ensured activity in the period following an | |
4790 | * unthrottle, this also covers the case in which the new bandwidth is | |
4791 | * insufficient to cover the existing bandwidth deficit. (Forcing the | |
4792 | * timer to remain active while there are any throttled entities.) | |
4793 | */ | |
4794 | cfs_b->idle = 0; | |
58088ad0 | 4795 | |
51f2176d BS |
4796 | return 0; |
4797 | ||
4798 | out_deactivate: | |
51f2176d | 4799 | return 1; |
58088ad0 | 4800 | } |
d3d9dc33 | 4801 | |
d8b4986d PT |
4802 | /* a cfs_rq won't donate quota below this amount */ |
4803 | static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC; | |
4804 | /* minimum remaining period time to redistribute slack quota */ | |
4805 | static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC; | |
4806 | /* how long we wait to gather additional slack before distributing */ | |
4807 | static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC; | |
4808 | ||
db06e78c BS |
4809 | /* |
4810 | * Are we near the end of the current quota period? | |
4811 | * | |
4812 | * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the | |
4961b6e1 | 4813 | * hrtimer base being cleared by hrtimer_start. In the case of |
db06e78c BS |
4814 | * migrate_hrtimers, base is never cleared, so we are fine. |
4815 | */ | |
d8b4986d PT |
4816 | static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) |
4817 | { | |
4818 | struct hrtimer *refresh_timer = &cfs_b->period_timer; | |
4819 | u64 remaining; | |
4820 | ||
4821 | /* if the call-back is running a quota refresh is already occurring */ | |
4822 | if (hrtimer_callback_running(refresh_timer)) | |
4823 | return 1; | |
4824 | ||
4825 | /* is a quota refresh about to occur? */ | |
4826 | remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer)); | |
4827 | if (remaining < min_expire) | |
4828 | return 1; | |
4829 | ||
4830 | return 0; | |
4831 | } | |
4832 | ||
4833 | static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b) | |
4834 | { | |
4835 | u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration; | |
4836 | ||
4837 | /* if there's a quota refresh soon don't bother with slack */ | |
4838 | if (runtime_refresh_within(cfs_b, min_left)) | |
4839 | return; | |
4840 | ||
4cfafd30 PZ |
4841 | hrtimer_start(&cfs_b->slack_timer, |
4842 | ns_to_ktime(cfs_bandwidth_slack_period), | |
4843 | HRTIMER_MODE_REL); | |
d8b4986d PT |
4844 | } |
4845 | ||
4846 | /* we know any runtime found here is valid as update_curr() precedes return */ | |
4847 | static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
4848 | { | |
4849 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
4850 | s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime; | |
4851 | ||
4852 | if (slack_runtime <= 0) | |
4853 | return; | |
4854 | ||
4855 | raw_spin_lock(&cfs_b->lock); | |
aadd794e | 4856 | if (cfs_b->quota != RUNTIME_INF) { |
d8b4986d PT |
4857 | cfs_b->runtime += slack_runtime; |
4858 | ||
4859 | /* we are under rq->lock, defer unthrottling using a timer */ | |
4860 | if (cfs_b->runtime > sched_cfs_bandwidth_slice() && | |
4861 | !list_empty(&cfs_b->throttled_cfs_rq)) | |
4862 | start_cfs_slack_bandwidth(cfs_b); | |
4863 | } | |
4864 | raw_spin_unlock(&cfs_b->lock); | |
4865 | ||
4866 | /* even if it's not valid for return we don't want to try again */ | |
4867 | cfs_rq->runtime_remaining -= slack_runtime; | |
4868 | } | |
4869 | ||
4870 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
4871 | { | |
56f570e5 PT |
4872 | if (!cfs_bandwidth_used()) |
4873 | return; | |
4874 | ||
fccfdc6f | 4875 | if (!cfs_rq->runtime_enabled || cfs_rq->nr_running) |
d8b4986d PT |
4876 | return; |
4877 | ||
4878 | __return_cfs_rq_runtime(cfs_rq); | |
4879 | } | |
4880 | ||
4881 | /* | |
4882 | * This is done with a timer (instead of inline with bandwidth return) since | |
4883 | * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs. | |
4884 | */ | |
4885 | static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b) | |
4886 | { | |
4887 | u64 runtime = 0, slice = sched_cfs_bandwidth_slice(); | |
d8b4986d PT |
4888 | |
4889 | /* confirm we're still not at a refresh boundary */ | |
db06e78c | 4890 | raw_spin_lock(&cfs_b->lock); |
3f7aa147 PA |
4891 | if (cfs_b->distribute_running) { |
4892 | raw_spin_unlock(&cfs_b->lock); | |
4893 | return; | |
4894 | } | |
4895 | ||
db06e78c BS |
4896 | if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) { |
4897 | raw_spin_unlock(&cfs_b->lock); | |
d8b4986d | 4898 | return; |
db06e78c | 4899 | } |
d8b4986d | 4900 | |
c06f04c7 | 4901 | if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) |
d8b4986d | 4902 | runtime = cfs_b->runtime; |
c06f04c7 | 4903 | |
3f7aa147 PA |
4904 | if (runtime) |
4905 | cfs_b->distribute_running = 1; | |
4906 | ||
d8b4986d PT |
4907 | raw_spin_unlock(&cfs_b->lock); |
4908 | ||
4909 | if (!runtime) | |
4910 | return; | |
4911 | ||
aadd794e | 4912 | runtime = distribute_cfs_runtime(cfs_b, runtime); |
d8b4986d PT |
4913 | |
4914 | raw_spin_lock(&cfs_b->lock); | |
aadd794e | 4915 | lsub_positive(&cfs_b->runtime, runtime); |
3f7aa147 | 4916 | cfs_b->distribute_running = 0; |
d8b4986d PT |
4917 | raw_spin_unlock(&cfs_b->lock); |
4918 | } | |
4919 | ||
d3d9dc33 PT |
4920 | /* |
4921 | * When a group wakes up we want to make sure that its quota is not already | |
4922 | * expired/exceeded, otherwise it may be allowed to steal additional ticks of | |
4923 | * runtime as update_curr() throttling can not not trigger until it's on-rq. | |
4924 | */ | |
4925 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq) | |
4926 | { | |
56f570e5 PT |
4927 | if (!cfs_bandwidth_used()) |
4928 | return; | |
4929 | ||
d3d9dc33 PT |
4930 | /* an active group must be handled by the update_curr()->put() path */ |
4931 | if (!cfs_rq->runtime_enabled || cfs_rq->curr) | |
4932 | return; | |
4933 | ||
4934 | /* ensure the group is not already throttled */ | |
4935 | if (cfs_rq_throttled(cfs_rq)) | |
4936 | return; | |
4937 | ||
4938 | /* update runtime allocation */ | |
4939 | account_cfs_rq_runtime(cfs_rq, 0); | |
4940 | if (cfs_rq->runtime_remaining <= 0) | |
4941 | throttle_cfs_rq(cfs_rq); | |
4942 | } | |
4943 | ||
55e16d30 PZ |
4944 | static void sync_throttle(struct task_group *tg, int cpu) |
4945 | { | |
4946 | struct cfs_rq *pcfs_rq, *cfs_rq; | |
4947 | ||
4948 | if (!cfs_bandwidth_used()) | |
4949 | return; | |
4950 | ||
4951 | if (!tg->parent) | |
4952 | return; | |
4953 | ||
4954 | cfs_rq = tg->cfs_rq[cpu]; | |
4955 | pcfs_rq = tg->parent->cfs_rq[cpu]; | |
4956 | ||
4957 | cfs_rq->throttle_count = pcfs_rq->throttle_count; | |
b8922125 | 4958 | cfs_rq->throttled_clock_task = rq_clock_task(cpu_rq(cpu)); |
55e16d30 PZ |
4959 | } |
4960 | ||
d3d9dc33 | 4961 | /* conditionally throttle active cfs_rq's from put_prev_entity() */ |
678d5718 | 4962 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
d3d9dc33 | 4963 | { |
56f570e5 | 4964 | if (!cfs_bandwidth_used()) |
678d5718 | 4965 | return false; |
56f570e5 | 4966 | |
d3d9dc33 | 4967 | if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0)) |
678d5718 | 4968 | return false; |
d3d9dc33 PT |
4969 | |
4970 | /* | |
4971 | * it's possible for a throttled entity to be forced into a running | |
4972 | * state (e.g. set_curr_task), in this case we're finished. | |
4973 | */ | |
4974 | if (cfs_rq_throttled(cfs_rq)) | |
678d5718 | 4975 | return true; |
d3d9dc33 PT |
4976 | |
4977 | throttle_cfs_rq(cfs_rq); | |
678d5718 | 4978 | return true; |
d3d9dc33 | 4979 | } |
029632fb | 4980 | |
029632fb PZ |
4981 | static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer) |
4982 | { | |
4983 | struct cfs_bandwidth *cfs_b = | |
4984 | container_of(timer, struct cfs_bandwidth, slack_timer); | |
77a4d1a1 | 4985 | |
029632fb PZ |
4986 | do_sched_cfs_slack_timer(cfs_b); |
4987 | ||
4988 | return HRTIMER_NORESTART; | |
4989 | } | |
4990 | ||
4c4d4175 PA |
4991 | extern const u64 max_cfs_quota_period; |
4992 | ||
029632fb PZ |
4993 | static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) |
4994 | { | |
4995 | struct cfs_bandwidth *cfs_b = | |
4996 | container_of(timer, struct cfs_bandwidth, period_timer); | |
029632fb PZ |
4997 | int overrun; |
4998 | int idle = 0; | |
4c4d4175 | 4999 | int count = 0; |
029632fb | 5000 | |
51f2176d | 5001 | raw_spin_lock(&cfs_b->lock); |
029632fb | 5002 | for (;;) { |
77a4d1a1 | 5003 | overrun = hrtimer_forward_now(timer, cfs_b->period); |
029632fb PZ |
5004 | if (!overrun) |
5005 | break; | |
5006 | ||
4c4d4175 PA |
5007 | if (++count > 3) { |
5008 | u64 new, old = ktime_to_ns(cfs_b->period); | |
5009 | ||
79972ba6 XZ |
5010 | /* |
5011 | * Grow period by a factor of 2 to avoid losing precision. | |
5012 | * Precision loss in the quota/period ratio can cause __cfs_schedulable | |
5013 | * to fail. | |
5014 | */ | |
5015 | new = old * 2; | |
5016 | if (new < max_cfs_quota_period) { | |
5017 | cfs_b->period = ns_to_ktime(new); | |
5018 | cfs_b->quota *= 2; | |
5019 | ||
5020 | pr_warn_ratelimited( | |
5021 | "cfs_period_timer[cpu%d]: period too short, scaling up (new cfs_period_us = %lld, cfs_quota_us = %lld)\n", | |
5022 | smp_processor_id(), | |
5023 | div_u64(new, NSEC_PER_USEC), | |
5024 | div_u64(cfs_b->quota, NSEC_PER_USEC)); | |
5025 | } else { | |
5026 | pr_warn_ratelimited( | |
5027 | "cfs_period_timer[cpu%d]: period too short, but cannot scale up without losing precision (cfs_period_us = %lld, cfs_quota_us = %lld)\n", | |
5028 | smp_processor_id(), | |
5029 | div_u64(old, NSEC_PER_USEC), | |
5030 | div_u64(cfs_b->quota, NSEC_PER_USEC)); | |
5031 | } | |
4c4d4175 PA |
5032 | |
5033 | /* reset count so we don't come right back in here */ | |
5034 | count = 0; | |
5035 | } | |
5036 | ||
029632fb PZ |
5037 | idle = do_sched_cfs_period_timer(cfs_b, overrun); |
5038 | } | |
4cfafd30 PZ |
5039 | if (idle) |
5040 | cfs_b->period_active = 0; | |
51f2176d | 5041 | raw_spin_unlock(&cfs_b->lock); |
029632fb PZ |
5042 | |
5043 | return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; | |
5044 | } | |
5045 | ||
5046 | void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) | |
5047 | { | |
5048 | raw_spin_lock_init(&cfs_b->lock); | |
5049 | cfs_b->runtime = 0; | |
5050 | cfs_b->quota = RUNTIME_INF; | |
5051 | cfs_b->period = ns_to_ktime(default_cfs_period()); | |
5052 | ||
5053 | INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq); | |
4cfafd30 | 5054 | hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED); |
029632fb PZ |
5055 | cfs_b->period_timer.function = sched_cfs_period_timer; |
5056 | hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
5057 | cfs_b->slack_timer.function = sched_cfs_slack_timer; | |
3f7aa147 | 5058 | cfs_b->distribute_running = 0; |
029632fb PZ |
5059 | } |
5060 | ||
5061 | static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
5062 | { | |
5063 | cfs_rq->runtime_enabled = 0; | |
5064 | INIT_LIST_HEAD(&cfs_rq->throttled_list); | |
5065 | } | |
5066 | ||
77a4d1a1 | 5067 | void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b) |
029632fb | 5068 | { |
4cfafd30 | 5069 | lockdep_assert_held(&cfs_b->lock); |
029632fb | 5070 | |
4cfafd30 PZ |
5071 | if (!cfs_b->period_active) { |
5072 | cfs_b->period_active = 1; | |
5073 | hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period); | |
5074 | hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED); | |
5075 | } | |
029632fb PZ |
5076 | } |
5077 | ||
5078 | static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) | |
5079 | { | |
7f1a169b TH |
5080 | /* init_cfs_bandwidth() was not called */ |
5081 | if (!cfs_b->throttled_cfs_rq.next) | |
5082 | return; | |
5083 | ||
029632fb PZ |
5084 | hrtimer_cancel(&cfs_b->period_timer); |
5085 | hrtimer_cancel(&cfs_b->slack_timer); | |
5086 | } | |
5087 | ||
502ce005 PZ |
5088 | /* |
5089 | * Both these cpu hotplug callbacks race against unregister_fair_sched_group() | |
5090 | * | |
5091 | * The race is harmless, since modifying bandwidth settings of unhooked group | |
5092 | * bits doesn't do much. | |
5093 | */ | |
5094 | ||
5095 | /* cpu online calback */ | |
0e59bdae KT |
5096 | static void __maybe_unused update_runtime_enabled(struct rq *rq) |
5097 | { | |
502ce005 | 5098 | struct task_group *tg; |
0e59bdae | 5099 | |
502ce005 PZ |
5100 | lockdep_assert_held(&rq->lock); |
5101 | ||
5102 | rcu_read_lock(); | |
5103 | list_for_each_entry_rcu(tg, &task_groups, list) { | |
5104 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; | |
5105 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; | |
0e59bdae KT |
5106 | |
5107 | raw_spin_lock(&cfs_b->lock); | |
5108 | cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; | |
5109 | raw_spin_unlock(&cfs_b->lock); | |
5110 | } | |
502ce005 | 5111 | rcu_read_unlock(); |
0e59bdae KT |
5112 | } |
5113 | ||
502ce005 | 5114 | /* cpu offline callback */ |
38dc3348 | 5115 | static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq) |
029632fb | 5116 | { |
502ce005 PZ |
5117 | struct task_group *tg; |
5118 | ||
5119 | lockdep_assert_held(&rq->lock); | |
5120 | ||
5121 | rcu_read_lock(); | |
5122 | list_for_each_entry_rcu(tg, &task_groups, list) { | |
5123 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; | |
029632fb | 5124 | |
029632fb PZ |
5125 | if (!cfs_rq->runtime_enabled) |
5126 | continue; | |
5127 | ||
5128 | /* | |
5129 | * clock_task is not advancing so we just need to make sure | |
5130 | * there's some valid quota amount | |
5131 | */ | |
51f2176d | 5132 | cfs_rq->runtime_remaining = 1; |
0e59bdae KT |
5133 | /* |
5134 | * Offline rq is schedulable till cpu is completely disabled | |
5135 | * in take_cpu_down(), so we prevent new cfs throttling here. | |
5136 | */ | |
5137 | cfs_rq->runtime_enabled = 0; | |
5138 | ||
029632fb PZ |
5139 | if (cfs_rq_throttled(cfs_rq)) |
5140 | unthrottle_cfs_rq(cfs_rq); | |
5141 | } | |
502ce005 | 5142 | rcu_read_unlock(); |
029632fb PZ |
5143 | } |
5144 | ||
5145 | #else /* CONFIG_CFS_BANDWIDTH */ | |
f1b17280 PT |
5146 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) |
5147 | { | |
78becc27 | 5148 | return rq_clock_task(rq_of(cfs_rq)); |
f1b17280 PT |
5149 | } |
5150 | ||
9dbdb155 | 5151 | static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {} |
678d5718 | 5152 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; } |
d3d9dc33 | 5153 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {} |
55e16d30 | 5154 | static inline void sync_throttle(struct task_group *tg, int cpu) {} |
6c16a6dc | 5155 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} |
85dac906 PT |
5156 | |
5157 | static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) | |
5158 | { | |
5159 | return 0; | |
5160 | } | |
64660c86 PT |
5161 | |
5162 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) | |
5163 | { | |
5164 | return 0; | |
5165 | } | |
5166 | ||
5167 | static inline int throttled_lb_pair(struct task_group *tg, | |
5168 | int src_cpu, int dest_cpu) | |
5169 | { | |
5170 | return 0; | |
5171 | } | |
029632fb PZ |
5172 | |
5173 | void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} | |
5174 | ||
5175 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
5176 | static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} | |
ab84d31e PT |
5177 | #endif |
5178 | ||
029632fb PZ |
5179 | static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
5180 | { | |
5181 | return NULL; | |
5182 | } | |
5183 | static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} | |
0e59bdae | 5184 | static inline void update_runtime_enabled(struct rq *rq) {} |
a4c96ae3 | 5185 | static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {} |
029632fb PZ |
5186 | |
5187 | #endif /* CONFIG_CFS_BANDWIDTH */ | |
5188 | ||
bf0f6f24 IM |
5189 | /************************************************** |
5190 | * CFS operations on tasks: | |
5191 | */ | |
5192 | ||
8f4d37ec PZ |
5193 | #ifdef CONFIG_SCHED_HRTICK |
5194 | static void hrtick_start_fair(struct rq *rq, struct task_struct *p) | |
5195 | { | |
8f4d37ec PZ |
5196 | struct sched_entity *se = &p->se; |
5197 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
5198 | ||
9148a3a1 | 5199 | SCHED_WARN_ON(task_rq(p) != rq); |
8f4d37ec | 5200 | |
8bf46a39 | 5201 | if (rq->cfs.h_nr_running > 1) { |
8f4d37ec PZ |
5202 | u64 slice = sched_slice(cfs_rq, se); |
5203 | u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime; | |
5204 | s64 delta = slice - ran; | |
5205 | ||
5206 | if (delta < 0) { | |
5207 | if (rq->curr == p) | |
8875125e | 5208 | resched_curr(rq); |
8f4d37ec PZ |
5209 | return; |
5210 | } | |
31656519 | 5211 | hrtick_start(rq, delta); |
8f4d37ec PZ |
5212 | } |
5213 | } | |
a4c2f00f PZ |
5214 | |
5215 | /* | |
5216 | * called from enqueue/dequeue and updates the hrtick when the | |
5217 | * current task is from our class and nr_running is low enough | |
5218 | * to matter. | |
5219 | */ | |
5220 | static void hrtick_update(struct rq *rq) | |
5221 | { | |
5222 | struct task_struct *curr = rq->curr; | |
5223 | ||
b39e66ea | 5224 | if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class) |
a4c2f00f PZ |
5225 | return; |
5226 | ||
5227 | if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency) | |
5228 | hrtick_start_fair(rq, curr); | |
5229 | } | |
55e12e5e | 5230 | #else /* !CONFIG_SCHED_HRTICK */ |
8f4d37ec PZ |
5231 | static inline void |
5232 | hrtick_start_fair(struct rq *rq, struct task_struct *p) | |
5233 | { | |
5234 | } | |
a4c2f00f PZ |
5235 | |
5236 | static inline void hrtick_update(struct rq *rq) | |
5237 | { | |
5238 | } | |
8f4d37ec PZ |
5239 | #endif |
5240 | ||
bf0f6f24 IM |
5241 | /* |
5242 | * The enqueue_task method is called before nr_running is | |
5243 | * increased. Here we update the fair scheduling stats and | |
5244 | * then put the task into the rbtree: | |
5245 | */ | |
ea87bb78 | 5246 | static void |
371fd7e7 | 5247 | enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
bf0f6f24 IM |
5248 | { |
5249 | struct cfs_rq *cfs_rq; | |
62fb1851 | 5250 | struct sched_entity *se = &p->se; |
bf0f6f24 | 5251 | |
8c34ab19 RW |
5252 | /* |
5253 | * If in_iowait is set, the code below may not trigger any cpufreq | |
5254 | * utilization updates, so do it here explicitly with the IOWAIT flag | |
5255 | * passed. | |
5256 | */ | |
5257 | if (p->in_iowait) | |
674e7541 | 5258 | cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT); |
8c34ab19 | 5259 | |
bf0f6f24 | 5260 | for_each_sched_entity(se) { |
62fb1851 | 5261 | if (se->on_rq) |
bf0f6f24 IM |
5262 | break; |
5263 | cfs_rq = cfs_rq_of(se); | |
88ec22d3 | 5264 | enqueue_entity(cfs_rq, se, flags); |
85dac906 PT |
5265 | |
5266 | /* | |
5267 | * end evaluation on encountering a throttled cfs_rq | |
5268 | * | |
5269 | * note: in the case of encountering a throttled cfs_rq we will | |
5270 | * post the final h_nr_running increment below. | |
e210bffd | 5271 | */ |
85dac906 PT |
5272 | if (cfs_rq_throttled(cfs_rq)) |
5273 | break; | |
953bfcd1 | 5274 | cfs_rq->h_nr_running++; |
85dac906 | 5275 | |
88ec22d3 | 5276 | flags = ENQUEUE_WAKEUP; |
bf0f6f24 | 5277 | } |
8f4d37ec | 5278 | |
2069dd75 | 5279 | for_each_sched_entity(se) { |
0f317143 | 5280 | cfs_rq = cfs_rq_of(se); |
953bfcd1 | 5281 | cfs_rq->h_nr_running++; |
2069dd75 | 5282 | |
85dac906 PT |
5283 | if (cfs_rq_throttled(cfs_rq)) |
5284 | break; | |
5285 | ||
88c0616e | 5286 | update_load_avg(cfs_rq, se, UPDATE_TG); |
1ea6c46a | 5287 | update_cfs_group(se); |
2069dd75 PZ |
5288 | } |
5289 | ||
cd126afe | 5290 | if (!se) |
72465447 | 5291 | add_nr_running(rq, 1); |
cd126afe | 5292 | |
a653325a PZ |
5293 | assert_list_leaf_cfs_rq(rq); |
5294 | ||
a4c2f00f | 5295 | hrtick_update(rq); |
bf0f6f24 IM |
5296 | } |
5297 | ||
2f36825b VP |
5298 | static void set_next_buddy(struct sched_entity *se); |
5299 | ||
bf0f6f24 IM |
5300 | /* |
5301 | * The dequeue_task method is called before nr_running is | |
5302 | * decreased. We remove the task from the rbtree and | |
5303 | * update the fair scheduling stats: | |
5304 | */ | |
371fd7e7 | 5305 | static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
bf0f6f24 IM |
5306 | { |
5307 | struct cfs_rq *cfs_rq; | |
62fb1851 | 5308 | struct sched_entity *se = &p->se; |
2f36825b | 5309 | int task_sleep = flags & DEQUEUE_SLEEP; |
bf0f6f24 IM |
5310 | |
5311 | for_each_sched_entity(se) { | |
5312 | cfs_rq = cfs_rq_of(se); | |
371fd7e7 | 5313 | dequeue_entity(cfs_rq, se, flags); |
85dac906 PT |
5314 | |
5315 | /* | |
5316 | * end evaluation on encountering a throttled cfs_rq | |
5317 | * | |
5318 | * note: in the case of encountering a throttled cfs_rq we will | |
5319 | * post the final h_nr_running decrement below. | |
5320 | */ | |
5321 | if (cfs_rq_throttled(cfs_rq)) | |
5322 | break; | |
953bfcd1 | 5323 | cfs_rq->h_nr_running--; |
2069dd75 | 5324 | |
bf0f6f24 | 5325 | /* Don't dequeue parent if it has other entities besides us */ |
2f36825b | 5326 | if (cfs_rq->load.weight) { |
754bd598 KK |
5327 | /* Avoid re-evaluating load for this entity: */ |
5328 | se = parent_entity(se); | |
2f36825b VP |
5329 | /* |
5330 | * Bias pick_next to pick a task from this cfs_rq, as | |
5331 | * p is sleeping when it is within its sched_slice. | |
5332 | */ | |
754bd598 KK |
5333 | if (task_sleep && se && !throttled_hierarchy(cfs_rq)) |
5334 | set_next_buddy(se); | |
bf0f6f24 | 5335 | break; |
2f36825b | 5336 | } |
371fd7e7 | 5337 | flags |= DEQUEUE_SLEEP; |
bf0f6f24 | 5338 | } |
8f4d37ec | 5339 | |
2069dd75 | 5340 | for_each_sched_entity(se) { |
0f317143 | 5341 | cfs_rq = cfs_rq_of(se); |
953bfcd1 | 5342 | cfs_rq->h_nr_running--; |
2069dd75 | 5343 | |
85dac906 PT |
5344 | if (cfs_rq_throttled(cfs_rq)) |
5345 | break; | |
5346 | ||
88c0616e | 5347 | update_load_avg(cfs_rq, se, UPDATE_TG); |
1ea6c46a | 5348 | update_cfs_group(se); |
2069dd75 PZ |
5349 | } |
5350 | ||
cd126afe | 5351 | if (!se) |
72465447 | 5352 | sub_nr_running(rq, 1); |
cd126afe | 5353 | |
a4c2f00f | 5354 | hrtick_update(rq); |
bf0f6f24 IM |
5355 | } |
5356 | ||
e7693a36 | 5357 | #ifdef CONFIG_SMP |
10e2f1ac PZ |
5358 | |
5359 | /* Working cpumask for: load_balance, load_balance_newidle. */ | |
5360 | DEFINE_PER_CPU(cpumask_var_t, load_balance_mask); | |
5361 | DEFINE_PER_CPU(cpumask_var_t, select_idle_mask); | |
5362 | ||
9fd81dd5 | 5363 | #ifdef CONFIG_NO_HZ_COMMON |
3289bdb4 PZ |
5364 | /* |
5365 | * per rq 'load' arrray crap; XXX kill this. | |
5366 | */ | |
5367 | ||
5368 | /* | |
d937cdc5 | 5369 | * The exact cpuload calculated at every tick would be: |
3289bdb4 | 5370 | * |
d937cdc5 PZ |
5371 | * load' = (1 - 1/2^i) * load + (1/2^i) * cur_load |
5372 | * | |
5373 | * If a cpu misses updates for n ticks (as it was idle) and update gets | |
5374 | * called on the n+1-th tick when cpu may be busy, then we have: | |
5375 | * | |
5376 | * load_n = (1 - 1/2^i)^n * load_0 | |
5377 | * load_n+1 = (1 - 1/2^i) * load_n + (1/2^i) * cur_load | |
3289bdb4 PZ |
5378 | * |
5379 | * decay_load_missed() below does efficient calculation of | |
3289bdb4 | 5380 | * |
d937cdc5 PZ |
5381 | * load' = (1 - 1/2^i)^n * load |
5382 | * | |
5383 | * Because x^(n+m) := x^n * x^m we can decompose any x^n in power-of-2 factors. | |
5384 | * This allows us to precompute the above in said factors, thereby allowing the | |
5385 | * reduction of an arbitrary n in O(log_2 n) steps. (See also | |
5386 | * fixed_power_int()) | |
3289bdb4 | 5387 | * |
d937cdc5 | 5388 | * The calculation is approximated on a 128 point scale. |
3289bdb4 PZ |
5389 | */ |
5390 | #define DEGRADE_SHIFT 7 | |
d937cdc5 PZ |
5391 | |
5392 | static const u8 degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128}; | |
5393 | static const u8 degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = { | |
5394 | { 0, 0, 0, 0, 0, 0, 0, 0 }, | |
5395 | { 64, 32, 8, 0, 0, 0, 0, 0 }, | |
5396 | { 96, 72, 40, 12, 1, 0, 0, 0 }, | |
5397 | { 112, 98, 75, 43, 15, 1, 0, 0 }, | |
5398 | { 120, 112, 98, 76, 45, 16, 2, 0 } | |
5399 | }; | |
3289bdb4 PZ |
5400 | |
5401 | /* | |
5402 | * Update cpu_load for any missed ticks, due to tickless idle. The backlog | |
5403 | * would be when CPU is idle and so we just decay the old load without | |
5404 | * adding any new load. | |
5405 | */ | |
5406 | static unsigned long | |
5407 | decay_load_missed(unsigned long load, unsigned long missed_updates, int idx) | |
5408 | { | |
5409 | int j = 0; | |
5410 | ||
5411 | if (!missed_updates) | |
5412 | return load; | |
5413 | ||
5414 | if (missed_updates >= degrade_zero_ticks[idx]) | |
5415 | return 0; | |
5416 | ||
5417 | if (idx == 1) | |
5418 | return load >> missed_updates; | |
5419 | ||
5420 | while (missed_updates) { | |
5421 | if (missed_updates % 2) | |
5422 | load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT; | |
5423 | ||
5424 | missed_updates >>= 1; | |
5425 | j++; | |
5426 | } | |
5427 | return load; | |
5428 | } | |
9fd81dd5 | 5429 | #endif /* CONFIG_NO_HZ_COMMON */ |
3289bdb4 | 5430 | |
59543275 | 5431 | /** |
cee1afce | 5432 | * __cpu_load_update - update the rq->cpu_load[] statistics |
59543275 BP |
5433 | * @this_rq: The rq to update statistics for |
5434 | * @this_load: The current load | |
5435 | * @pending_updates: The number of missed updates | |
59543275 | 5436 | * |
3289bdb4 | 5437 | * Update rq->cpu_load[] statistics. This function is usually called every |
59543275 BP |
5438 | * scheduler tick (TICK_NSEC). |
5439 | * | |
5440 | * This function computes a decaying average: | |
5441 | * | |
5442 | * load[i]' = (1 - 1/2^i) * load[i] + (1/2^i) * load | |
5443 | * | |
5444 | * Because of NOHZ it might not get called on every tick which gives need for | |
5445 | * the @pending_updates argument. | |
5446 | * | |
5447 | * load[i]_n = (1 - 1/2^i) * load[i]_n-1 + (1/2^i) * load_n-1 | |
5448 | * = A * load[i]_n-1 + B ; A := (1 - 1/2^i), B := (1/2^i) * load | |
5449 | * = A * (A * load[i]_n-2 + B) + B | |
5450 | * = A * (A * (A * load[i]_n-3 + B) + B) + B | |
5451 | * = A^3 * load[i]_n-3 + (A^2 + A + 1) * B | |
5452 | * = A^n * load[i]_0 + (A^(n-1) + A^(n-2) + ... + 1) * B | |
5453 | * = A^n * load[i]_0 + ((1 - A^n) / (1 - A)) * B | |
5454 | * = (1 - 1/2^i)^n * (load[i]_0 - load) + load | |
5455 | * | |
5456 | * In the above we've assumed load_n := load, which is true for NOHZ_FULL as | |
5457 | * any change in load would have resulted in the tick being turned back on. | |
5458 | * | |
5459 | * For regular NOHZ, this reduces to: | |
5460 | * | |
5461 | * load[i]_n = (1 - 1/2^i)^n * load[i]_0 | |
5462 | * | |
5463 | * see decay_load_misses(). For NOHZ_FULL we get to subtract and add the extra | |
1f41906a | 5464 | * term. |
3289bdb4 | 5465 | */ |
1f41906a FW |
5466 | static void cpu_load_update(struct rq *this_rq, unsigned long this_load, |
5467 | unsigned long pending_updates) | |
3289bdb4 | 5468 | { |
9fd81dd5 | 5469 | unsigned long __maybe_unused tickless_load = this_rq->cpu_load[0]; |
3289bdb4 PZ |
5470 | int i, scale; |
5471 | ||
5472 | this_rq->nr_load_updates++; | |
5473 | ||
5474 | /* Update our load: */ | |
5475 | this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */ | |
5476 | for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) { | |
5477 | unsigned long old_load, new_load; | |
5478 | ||
5479 | /* scale is effectively 1 << i now, and >> i divides by scale */ | |
5480 | ||
7400d3bb | 5481 | old_load = this_rq->cpu_load[i]; |
9fd81dd5 | 5482 | #ifdef CONFIG_NO_HZ_COMMON |
3289bdb4 | 5483 | old_load = decay_load_missed(old_load, pending_updates - 1, i); |
7400d3bb BP |
5484 | if (tickless_load) { |
5485 | old_load -= decay_load_missed(tickless_load, pending_updates - 1, i); | |
5486 | /* | |
5487 | * old_load can never be a negative value because a | |
5488 | * decayed tickless_load cannot be greater than the | |
5489 | * original tickless_load. | |
5490 | */ | |
5491 | old_load += tickless_load; | |
5492 | } | |
9fd81dd5 | 5493 | #endif |
3289bdb4 PZ |
5494 | new_load = this_load; |
5495 | /* | |
5496 | * Round up the averaging division if load is increasing. This | |
5497 | * prevents us from getting stuck on 9 if the load is 10, for | |
5498 | * example. | |
5499 | */ | |
5500 | if (new_load > old_load) | |
5501 | new_load += scale - 1; | |
5502 | ||
5503 | this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i; | |
5504 | } | |
5505 | ||
5506 | sched_avg_update(this_rq); | |
5507 | } | |
5508 | ||
7ea241af | 5509 | /* Used instead of source_load when we know the type == 0 */ |
c7132dd6 | 5510 | static unsigned long weighted_cpuload(struct rq *rq) |
7ea241af | 5511 | { |
c7132dd6 | 5512 | return cfs_rq_runnable_load_avg(&rq->cfs); |
7ea241af YD |
5513 | } |
5514 | ||
3289bdb4 | 5515 | #ifdef CONFIG_NO_HZ_COMMON |
1f41906a FW |
5516 | /* |
5517 | * There is no sane way to deal with nohz on smp when using jiffies because the | |
5518 | * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading | |
5519 | * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}. | |
5520 | * | |
5521 | * Therefore we need to avoid the delta approach from the regular tick when | |
5522 | * possible since that would seriously skew the load calculation. This is why we | |
5523 | * use cpu_load_update_periodic() for CPUs out of nohz. However we'll rely on | |
5524 | * jiffies deltas for updates happening while in nohz mode (idle ticks, idle | |
5525 | * loop exit, nohz_idle_balance, nohz full exit...) | |
5526 | * | |
5527 | * This means we might still be one tick off for nohz periods. | |
5528 | */ | |
5529 | ||
5530 | static void cpu_load_update_nohz(struct rq *this_rq, | |
5531 | unsigned long curr_jiffies, | |
5532 | unsigned long load) | |
be68a682 FW |
5533 | { |
5534 | unsigned long pending_updates; | |
5535 | ||
5536 | pending_updates = curr_jiffies - this_rq->last_load_update_tick; | |
5537 | if (pending_updates) { | |
5538 | this_rq->last_load_update_tick = curr_jiffies; | |
5539 | /* | |
5540 | * In the regular NOHZ case, we were idle, this means load 0. | |
5541 | * In the NOHZ_FULL case, we were non-idle, we should consider | |
5542 | * its weighted load. | |
5543 | */ | |
1f41906a | 5544 | cpu_load_update(this_rq, load, pending_updates); |
be68a682 FW |
5545 | } |
5546 | } | |
5547 | ||
3289bdb4 PZ |
5548 | /* |
5549 | * Called from nohz_idle_balance() to update the load ratings before doing the | |
5550 | * idle balance. | |
5551 | */ | |
cee1afce | 5552 | static void cpu_load_update_idle(struct rq *this_rq) |
3289bdb4 | 5553 | { |
3289bdb4 PZ |
5554 | /* |
5555 | * bail if there's load or we're actually up-to-date. | |
5556 | */ | |
c7132dd6 | 5557 | if (weighted_cpuload(this_rq)) |
3289bdb4 PZ |
5558 | return; |
5559 | ||
1f41906a | 5560 | cpu_load_update_nohz(this_rq, READ_ONCE(jiffies), 0); |
3289bdb4 PZ |
5561 | } |
5562 | ||
5563 | /* | |
1f41906a FW |
5564 | * Record CPU load on nohz entry so we know the tickless load to account |
5565 | * on nohz exit. cpu_load[0] happens then to be updated more frequently | |
5566 | * than other cpu_load[idx] but it should be fine as cpu_load readers | |
5567 | * shouldn't rely into synchronized cpu_load[*] updates. | |
3289bdb4 | 5568 | */ |
1f41906a | 5569 | void cpu_load_update_nohz_start(void) |
3289bdb4 PZ |
5570 | { |
5571 | struct rq *this_rq = this_rq(); | |
1f41906a FW |
5572 | |
5573 | /* | |
5574 | * This is all lockless but should be fine. If weighted_cpuload changes | |
5575 | * concurrently we'll exit nohz. And cpu_load write can race with | |
5576 | * cpu_load_update_idle() but both updater would be writing the same. | |
5577 | */ | |
c7132dd6 | 5578 | this_rq->cpu_load[0] = weighted_cpuload(this_rq); |
1f41906a FW |
5579 | } |
5580 | ||
5581 | /* | |
5582 | * Account the tickless load in the end of a nohz frame. | |
5583 | */ | |
5584 | void cpu_load_update_nohz_stop(void) | |
5585 | { | |
316c1608 | 5586 | unsigned long curr_jiffies = READ_ONCE(jiffies); |
1f41906a FW |
5587 | struct rq *this_rq = this_rq(); |
5588 | unsigned long load; | |
8a8c69c3 | 5589 | struct rq_flags rf; |
3289bdb4 PZ |
5590 | |
5591 | if (curr_jiffies == this_rq->last_load_update_tick) | |
5592 | return; | |
5593 | ||
c7132dd6 | 5594 | load = weighted_cpuload(this_rq); |
8a8c69c3 | 5595 | rq_lock(this_rq, &rf); |
b52fad2d | 5596 | update_rq_clock(this_rq); |
1f41906a | 5597 | cpu_load_update_nohz(this_rq, curr_jiffies, load); |
8a8c69c3 | 5598 | rq_unlock(this_rq, &rf); |
3289bdb4 | 5599 | } |
1f41906a FW |
5600 | #else /* !CONFIG_NO_HZ_COMMON */ |
5601 | static inline void cpu_load_update_nohz(struct rq *this_rq, | |
5602 | unsigned long curr_jiffies, | |
5603 | unsigned long load) { } | |
5604 | #endif /* CONFIG_NO_HZ_COMMON */ | |
5605 | ||
5606 | static void cpu_load_update_periodic(struct rq *this_rq, unsigned long load) | |
5607 | { | |
9fd81dd5 | 5608 | #ifdef CONFIG_NO_HZ_COMMON |
1f41906a FW |
5609 | /* See the mess around cpu_load_update_nohz(). */ |
5610 | this_rq->last_load_update_tick = READ_ONCE(jiffies); | |
9fd81dd5 | 5611 | #endif |
1f41906a FW |
5612 | cpu_load_update(this_rq, load, 1); |
5613 | } | |
3289bdb4 PZ |
5614 | |
5615 | /* | |
5616 | * Called from scheduler_tick() | |
5617 | */ | |
cee1afce | 5618 | void cpu_load_update_active(struct rq *this_rq) |
3289bdb4 | 5619 | { |
c7132dd6 | 5620 | unsigned long load = weighted_cpuload(this_rq); |
1f41906a FW |
5621 | |
5622 | if (tick_nohz_tick_stopped()) | |
5623 | cpu_load_update_nohz(this_rq, READ_ONCE(jiffies), load); | |
5624 | else | |
5625 | cpu_load_update_periodic(this_rq, load); | |
3289bdb4 PZ |
5626 | } |
5627 | ||
029632fb PZ |
5628 | /* |
5629 | * Return a low guess at the load of a migration-source cpu weighted | |
5630 | * according to the scheduling class and "nice" value. | |
5631 | * | |
5632 | * We want to under-estimate the load of migration sources, to | |
5633 | * balance conservatively. | |
5634 | */ | |
5635 | static unsigned long source_load(int cpu, int type) | |
5636 | { | |
5637 | struct rq *rq = cpu_rq(cpu); | |
c7132dd6 | 5638 | unsigned long total = weighted_cpuload(rq); |
029632fb PZ |
5639 | |
5640 | if (type == 0 || !sched_feat(LB_BIAS)) | |
5641 | return total; | |
5642 | ||
5643 | return min(rq->cpu_load[type-1], total); | |
5644 | } | |
5645 | ||
5646 | /* | |
5647 | * Return a high guess at the load of a migration-target cpu weighted | |
5648 | * according to the scheduling class and "nice" value. | |
5649 | */ | |
5650 | static unsigned long target_load(int cpu, int type) | |
5651 | { | |
5652 | struct rq *rq = cpu_rq(cpu); | |
c7132dd6 | 5653 | unsigned long total = weighted_cpuload(rq); |
029632fb PZ |
5654 | |
5655 | if (type == 0 || !sched_feat(LB_BIAS)) | |
5656 | return total; | |
5657 | ||
5658 | return max(rq->cpu_load[type-1], total); | |
5659 | } | |
5660 | ||
ced549fa | 5661 | static unsigned long capacity_of(int cpu) |
029632fb | 5662 | { |
ced549fa | 5663 | return cpu_rq(cpu)->cpu_capacity; |
029632fb PZ |
5664 | } |
5665 | ||
ca6d75e6 VG |
5666 | static unsigned long capacity_orig_of(int cpu) |
5667 | { | |
5668 | return cpu_rq(cpu)->cpu_capacity_orig; | |
5669 | } | |
5670 | ||
029632fb PZ |
5671 | static unsigned long cpu_avg_load_per_task(int cpu) |
5672 | { | |
5673 | struct rq *rq = cpu_rq(cpu); | |
316c1608 | 5674 | unsigned long nr_running = READ_ONCE(rq->cfs.h_nr_running); |
c7132dd6 | 5675 | unsigned long load_avg = weighted_cpuload(rq); |
029632fb PZ |
5676 | |
5677 | if (nr_running) | |
b92486cb | 5678 | return load_avg / nr_running; |
029632fb PZ |
5679 | |
5680 | return 0; | |
5681 | } | |
5682 | ||
c58d25f3 PZ |
5683 | static void record_wakee(struct task_struct *p) |
5684 | { | |
5685 | /* | |
5686 | * Only decay a single time; tasks that have less then 1 wakeup per | |
5687 | * jiffy will not have built up many flips. | |
5688 | */ | |
5689 | if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) { | |
5690 | current->wakee_flips >>= 1; | |
5691 | current->wakee_flip_decay_ts = jiffies; | |
5692 | } | |
5693 | ||
5694 | if (current->last_wakee != p) { | |
5695 | current->last_wakee = p; | |
5696 | current->wakee_flips++; | |
5697 | } | |
5698 | } | |
5699 | ||
63b0e9ed MG |
5700 | /* |
5701 | * Detect M:N waker/wakee relationships via a switching-frequency heuristic. | |
c58d25f3 | 5702 | * |
63b0e9ed | 5703 | * A waker of many should wake a different task than the one last awakened |
c58d25f3 PZ |
5704 | * at a frequency roughly N times higher than one of its wakees. |
5705 | * | |
5706 | * In order to determine whether we should let the load spread vs consolidating | |
5707 | * to shared cache, we look for a minimum 'flip' frequency of llc_size in one | |
5708 | * partner, and a factor of lls_size higher frequency in the other. | |
5709 | * | |
5710 | * With both conditions met, we can be relatively sure that the relationship is | |
5711 | * non-monogamous, with partner count exceeding socket size. | |
5712 | * | |
5713 | * Waker/wakee being client/server, worker/dispatcher, interrupt source or | |
5714 | * whatever is irrelevant, spread criteria is apparent partner count exceeds | |
5715 | * socket size. | |
63b0e9ed | 5716 | */ |
62470419 MW |
5717 | static int wake_wide(struct task_struct *p) |
5718 | { | |
63b0e9ed MG |
5719 | unsigned int master = current->wakee_flips; |
5720 | unsigned int slave = p->wakee_flips; | |
7d9ffa89 | 5721 | int factor = this_cpu_read(sd_llc_size); |
62470419 | 5722 | |
63b0e9ed MG |
5723 | if (master < slave) |
5724 | swap(master, slave); | |
5725 | if (slave < factor || master < slave * factor) | |
5726 | return 0; | |
5727 | return 1; | |
62470419 MW |
5728 | } |
5729 | ||
90001d67 | 5730 | /* |
d153b153 PZ |
5731 | * The purpose of wake_affine() is to quickly determine on which CPU we can run |
5732 | * soonest. For the purpose of speed we only consider the waking and previous | |
5733 | * CPU. | |
90001d67 | 5734 | * |
d153b153 PZ |
5735 | * wake_affine_idle() - only considers 'now', it check if the waking CPU is (or |
5736 | * will be) idle. | |
f2cdd9cc PZ |
5737 | * |
5738 | * wake_affine_weight() - considers the weight to reflect the average | |
5739 | * scheduling latency of the CPUs. This seems to work | |
5740 | * for the overloaded case. | |
90001d67 | 5741 | */ |
90001d67 | 5742 | |
90001d67 | 5743 | static bool |
d153b153 PZ |
5744 | wake_affine_idle(struct sched_domain *sd, struct task_struct *p, |
5745 | int this_cpu, int prev_cpu, int sync) | |
90001d67 | 5746 | { |
d153b153 | 5747 | if (idle_cpu(this_cpu)) |
90001d67 | 5748 | return true; |
90001d67 | 5749 | |
d153b153 PZ |
5750 | if (sync && cpu_rq(this_cpu)->nr_running == 1) |
5751 | return true; | |
90001d67 | 5752 | |
d153b153 | 5753 | return false; |
90001d67 PZ |
5754 | } |
5755 | ||
90001d67 | 5756 | static bool |
f2cdd9cc PZ |
5757 | wake_affine_weight(struct sched_domain *sd, struct task_struct *p, |
5758 | int this_cpu, int prev_cpu, int sync) | |
90001d67 | 5759 | { |
90001d67 PZ |
5760 | s64 this_eff_load, prev_eff_load; |
5761 | unsigned long task_load; | |
5762 | ||
f2cdd9cc PZ |
5763 | this_eff_load = target_load(this_cpu, sd->wake_idx); |
5764 | prev_eff_load = source_load(prev_cpu, sd->wake_idx); | |
90001d67 | 5765 | |
90001d67 PZ |
5766 | if (sync) { |
5767 | unsigned long current_load = task_h_load(current); | |
5768 | ||
f2cdd9cc | 5769 | if (current_load > this_eff_load) |
90001d67 PZ |
5770 | return true; |
5771 | ||
f2cdd9cc | 5772 | this_eff_load -= current_load; |
90001d67 PZ |
5773 | } |
5774 | ||
90001d67 PZ |
5775 | task_load = task_h_load(p); |
5776 | ||
f2cdd9cc PZ |
5777 | this_eff_load += task_load; |
5778 | if (sched_feat(WA_BIAS)) | |
5779 | this_eff_load *= 100; | |
5780 | this_eff_load *= capacity_of(prev_cpu); | |
90001d67 | 5781 | |
f2cdd9cc PZ |
5782 | prev_eff_load -= task_load; |
5783 | if (sched_feat(WA_BIAS)) | |
5784 | prev_eff_load *= 100 + (sd->imbalance_pct - 100) / 2; | |
5785 | prev_eff_load *= capacity_of(this_cpu); | |
90001d67 PZ |
5786 | |
5787 | return this_eff_load <= prev_eff_load; | |
5788 | } | |
5789 | ||
772bd008 MR |
5790 | static int wake_affine(struct sched_domain *sd, struct task_struct *p, |
5791 | int prev_cpu, int sync) | |
098fb9db | 5792 | { |
3fed382b | 5793 | int this_cpu = smp_processor_id(); |
d153b153 | 5794 | bool affine = false; |
098fb9db | 5795 | |
d153b153 PZ |
5796 | if (sched_feat(WA_IDLE) && !affine) |
5797 | affine = wake_affine_idle(sd, p, this_cpu, prev_cpu, sync); | |
90001d67 | 5798 | |
f2cdd9cc PZ |
5799 | if (sched_feat(WA_WEIGHT) && !affine) |
5800 | affine = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync); | |
098fb9db | 5801 | |
ae92882e | 5802 | schedstat_inc(p->se.statistics.nr_wakeups_affine_attempts); |
3fed382b RR |
5803 | if (affine) { |
5804 | schedstat_inc(sd->ttwu_move_affine); | |
5805 | schedstat_inc(p->se.statistics.nr_wakeups_affine); | |
5806 | } | |
098fb9db | 5807 | |
3fed382b | 5808 | return affine; |
098fb9db IM |
5809 | } |
5810 | ||
6a0b19c0 MR |
5811 | static inline int task_util(struct task_struct *p); |
5812 | static int cpu_util_wake(int cpu, struct task_struct *p); | |
5813 | ||
5814 | static unsigned long capacity_spare_wake(int cpu, struct task_struct *p) | |
5815 | { | |
5816 | return capacity_orig_of(cpu) - cpu_util_wake(cpu, p); | |
5817 | } | |
5818 | ||
aaee1203 PZ |
5819 | /* |
5820 | * find_idlest_group finds and returns the least busy CPU group within the | |
5821 | * domain. | |
6fee85cc BJ |
5822 | * |
5823 | * Assumes p is allowed on at least one CPU in sd. | |
aaee1203 PZ |
5824 | */ |
5825 | static struct sched_group * | |
78e7ed53 | 5826 | find_idlest_group(struct sched_domain *sd, struct task_struct *p, |
c44f2a02 | 5827 | int this_cpu, int sd_flag) |
e7693a36 | 5828 | { |
b3bd3de6 | 5829 | struct sched_group *idlest = NULL, *group = sd->groups; |
6a0b19c0 | 5830 | struct sched_group *most_spare_sg = NULL; |
0d10ab95 BJ |
5831 | unsigned long min_runnable_load = ULONG_MAX; |
5832 | unsigned long this_runnable_load = ULONG_MAX; | |
5833 | unsigned long min_avg_load = ULONG_MAX, this_avg_load = ULONG_MAX; | |
6a0b19c0 | 5834 | unsigned long most_spare = 0, this_spare = 0; |
c44f2a02 | 5835 | int load_idx = sd->forkexec_idx; |
6b94780e VG |
5836 | int imbalance_scale = 100 + (sd->imbalance_pct-100)/2; |
5837 | unsigned long imbalance = scale_load_down(NICE_0_LOAD) * | |
5838 | (sd->imbalance_pct-100) / 100; | |
e7693a36 | 5839 | |
c44f2a02 VG |
5840 | if (sd_flag & SD_BALANCE_WAKE) |
5841 | load_idx = sd->wake_idx; | |
5842 | ||
aaee1203 | 5843 | do { |
6b94780e VG |
5844 | unsigned long load, avg_load, runnable_load; |
5845 | unsigned long spare_cap, max_spare_cap; | |
aaee1203 PZ |
5846 | int local_group; |
5847 | int i; | |
e7693a36 | 5848 | |
aaee1203 | 5849 | /* Skip over this group if it has no CPUs allowed */ |
ae4df9d6 | 5850 | if (!cpumask_intersects(sched_group_span(group), |
0c98d344 | 5851 | &p->cpus_allowed)) |
aaee1203 PZ |
5852 | continue; |
5853 | ||
5854 | local_group = cpumask_test_cpu(this_cpu, | |
ae4df9d6 | 5855 | sched_group_span(group)); |
aaee1203 | 5856 | |
6a0b19c0 MR |
5857 | /* |
5858 | * Tally up the load of all CPUs in the group and find | |
5859 | * the group containing the CPU with most spare capacity. | |
5860 | */ | |
aaee1203 | 5861 | avg_load = 0; |
6b94780e | 5862 | runnable_load = 0; |
6a0b19c0 | 5863 | max_spare_cap = 0; |
aaee1203 | 5864 | |
ae4df9d6 | 5865 | for_each_cpu(i, sched_group_span(group)) { |
aaee1203 PZ |
5866 | /* Bias balancing toward cpus of our domain */ |
5867 | if (local_group) | |
5868 | load = source_load(i, load_idx); | |
5869 | else | |
5870 | load = target_load(i, load_idx); | |
5871 | ||
6b94780e VG |
5872 | runnable_load += load; |
5873 | ||
5874 | avg_load += cfs_rq_load_avg(&cpu_rq(i)->cfs); | |
6a0b19c0 MR |
5875 | |
5876 | spare_cap = capacity_spare_wake(i, p); | |
5877 | ||
5878 | if (spare_cap > max_spare_cap) | |
5879 | max_spare_cap = spare_cap; | |
aaee1203 PZ |
5880 | } |
5881 | ||
63b2ca30 | 5882 | /* Adjust by relative CPU capacity of the group */ |
6b94780e VG |
5883 | avg_load = (avg_load * SCHED_CAPACITY_SCALE) / |
5884 | group->sgc->capacity; | |
5885 | runnable_load = (runnable_load * SCHED_CAPACITY_SCALE) / | |
5886 | group->sgc->capacity; | |
aaee1203 PZ |
5887 | |
5888 | if (local_group) { | |
6b94780e VG |
5889 | this_runnable_load = runnable_load; |
5890 | this_avg_load = avg_load; | |
6a0b19c0 MR |
5891 | this_spare = max_spare_cap; |
5892 | } else { | |
6b94780e VG |
5893 | if (min_runnable_load > (runnable_load + imbalance)) { |
5894 | /* | |
5895 | * The runnable load is significantly smaller | |
5896 | * so we can pick this new cpu | |
5897 | */ | |
5898 | min_runnable_load = runnable_load; | |
5899 | min_avg_load = avg_load; | |
5900 | idlest = group; | |
5901 | } else if ((runnable_load < (min_runnable_load + imbalance)) && | |
5902 | (100*min_avg_load > imbalance_scale*avg_load)) { | |
5903 | /* | |
5904 | * The runnable loads are close so take the | |
5905 | * blocked load into account through avg_load. | |
5906 | */ | |
5907 | min_avg_load = avg_load; | |
6a0b19c0 MR |
5908 | idlest = group; |
5909 | } | |
5910 | ||
5911 | if (most_spare < max_spare_cap) { | |
5912 | most_spare = max_spare_cap; | |
5913 | most_spare_sg = group; | |
5914 | } | |
aaee1203 PZ |
5915 | } |
5916 | } while (group = group->next, group != sd->groups); | |
5917 | ||
6a0b19c0 MR |
5918 | /* |
5919 | * The cross-over point between using spare capacity or least load | |
5920 | * is too conservative for high utilization tasks on partially | |
5921 | * utilized systems if we require spare_capacity > task_util(p), | |
5922 | * so we allow for some task stuffing by using | |
5923 | * spare_capacity > task_util(p)/2. | |
f519a3f1 VG |
5924 | * |
5925 | * Spare capacity can't be used for fork because the utilization has | |
5926 | * not been set yet, we must first select a rq to compute the initial | |
5927 | * utilization. | |
6a0b19c0 | 5928 | */ |
f519a3f1 VG |
5929 | if (sd_flag & SD_BALANCE_FORK) |
5930 | goto skip_spare; | |
5931 | ||
6a0b19c0 | 5932 | if (this_spare > task_util(p) / 2 && |
6b94780e | 5933 | imbalance_scale*this_spare > 100*most_spare) |
6a0b19c0 | 5934 | return NULL; |
6b94780e VG |
5935 | |
5936 | if (most_spare > task_util(p) / 2) | |
6a0b19c0 MR |
5937 | return most_spare_sg; |
5938 | ||
f519a3f1 | 5939 | skip_spare: |
6b94780e VG |
5940 | if (!idlest) |
5941 | return NULL; | |
5942 | ||
5943 | if (min_runnable_load > (this_runnable_load + imbalance)) | |
aaee1203 | 5944 | return NULL; |
6b94780e VG |
5945 | |
5946 | if ((this_runnable_load < (min_runnable_load + imbalance)) && | |
5947 | (100*this_avg_load < imbalance_scale*min_avg_load)) | |
5948 | return NULL; | |
5949 | ||
aaee1203 PZ |
5950 | return idlest; |
5951 | } | |
5952 | ||
5953 | /* | |
18bd1b4b | 5954 | * find_idlest_group_cpu - find the idlest cpu among the cpus in group. |
aaee1203 PZ |
5955 | */ |
5956 | static int | |
18bd1b4b | 5957 | find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) |
aaee1203 PZ |
5958 | { |
5959 | unsigned long load, min_load = ULONG_MAX; | |
83a0a96a NP |
5960 | unsigned int min_exit_latency = UINT_MAX; |
5961 | u64 latest_idle_timestamp = 0; | |
5962 | int least_loaded_cpu = this_cpu; | |
5963 | int shallowest_idle_cpu = -1; | |
aaee1203 PZ |
5964 | int i; |
5965 | ||
eaecf41f MR |
5966 | /* Check if we have any choice: */ |
5967 | if (group->group_weight == 1) | |
ae4df9d6 | 5968 | return cpumask_first(sched_group_span(group)); |
eaecf41f | 5969 | |
aaee1203 | 5970 | /* Traverse only the allowed CPUs */ |
ae4df9d6 | 5971 | for_each_cpu_and(i, sched_group_span(group), &p->cpus_allowed) { |
83a0a96a NP |
5972 | if (idle_cpu(i)) { |
5973 | struct rq *rq = cpu_rq(i); | |
5974 | struct cpuidle_state *idle = idle_get_state(rq); | |
5975 | if (idle && idle->exit_latency < min_exit_latency) { | |
5976 | /* | |
5977 | * We give priority to a CPU whose idle state | |
5978 | * has the smallest exit latency irrespective | |
5979 | * of any idle timestamp. | |
5980 | */ | |
5981 | min_exit_latency = idle->exit_latency; | |
5982 | latest_idle_timestamp = rq->idle_stamp; | |
5983 | shallowest_idle_cpu = i; | |
5984 | } else if ((!idle || idle->exit_latency == min_exit_latency) && | |
5985 | rq->idle_stamp > latest_idle_timestamp) { | |
5986 | /* | |
5987 | * If equal or no active idle state, then | |
5988 | * the most recently idled CPU might have | |
5989 | * a warmer cache. | |
5990 | */ | |
5991 | latest_idle_timestamp = rq->idle_stamp; | |
5992 | shallowest_idle_cpu = i; | |
5993 | } | |
9f96742a | 5994 | } else if (shallowest_idle_cpu == -1) { |
c7132dd6 | 5995 | load = weighted_cpuload(cpu_rq(i)); |
83a0a96a NP |
5996 | if (load < min_load || (load == min_load && i == this_cpu)) { |
5997 | min_load = load; | |
5998 | least_loaded_cpu = i; | |
5999 | } | |
e7693a36 GH |
6000 | } |
6001 | } | |
6002 | ||
83a0a96a | 6003 | return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu; |
aaee1203 | 6004 | } |
e7693a36 | 6005 | |
18bd1b4b BJ |
6006 | static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p, |
6007 | int cpu, int prev_cpu, int sd_flag) | |
6008 | { | |
93f50f90 | 6009 | int new_cpu = cpu; |
18bd1b4b | 6010 | |
6fee85cc BJ |
6011 | if (!cpumask_intersects(sched_domain_span(sd), &p->cpus_allowed)) |
6012 | return prev_cpu; | |
6013 | ||
18bd1b4b BJ |
6014 | while (sd) { |
6015 | struct sched_group *group; | |
6016 | struct sched_domain *tmp; | |
6017 | int weight; | |
6018 | ||
6019 | if (!(sd->flags & sd_flag)) { | |
6020 | sd = sd->child; | |
6021 | continue; | |
6022 | } | |
6023 | ||
6024 | group = find_idlest_group(sd, p, cpu, sd_flag); | |
6025 | if (!group) { | |
6026 | sd = sd->child; | |
6027 | continue; | |
6028 | } | |
6029 | ||
6030 | new_cpu = find_idlest_group_cpu(group, p, cpu); | |
e90381ea | 6031 | if (new_cpu == cpu) { |
18bd1b4b BJ |
6032 | /* Now try balancing at a lower domain level of cpu */ |
6033 | sd = sd->child; | |
6034 | continue; | |
6035 | } | |
6036 | ||
6037 | /* Now try balancing at a lower domain level of new_cpu */ | |
6038 | cpu = new_cpu; | |
6039 | weight = sd->span_weight; | |
6040 | sd = NULL; | |
6041 | for_each_domain(cpu, tmp) { | |
6042 | if (weight <= tmp->span_weight) | |
6043 | break; | |
6044 | if (tmp->flags & sd_flag) | |
6045 | sd = tmp; | |
6046 | } | |
6047 | /* while loop will break here if sd == NULL */ | |
6048 | } | |
6049 | ||
6050 | return new_cpu; | |
6051 | } | |
6052 | ||
10e2f1ac | 6053 | #ifdef CONFIG_SCHED_SMT |
53d195f2 | 6054 | DEFINE_STATIC_KEY_FALSE(sched_smt_present); |
67cd6fac | 6055 | EXPORT_SYMBOL_GPL(sched_smt_present); |
10e2f1ac PZ |
6056 | |
6057 | static inline void set_idle_cores(int cpu, int val) | |
6058 | { | |
6059 | struct sched_domain_shared *sds; | |
6060 | ||
6061 | sds = rcu_dereference(per_cpu(sd_llc_shared, cpu)); | |
6062 | if (sds) | |
6063 | WRITE_ONCE(sds->has_idle_cores, val); | |
6064 | } | |
6065 | ||
6066 | static inline bool test_idle_cores(int cpu, bool def) | |
6067 | { | |
6068 | struct sched_domain_shared *sds; | |
6069 | ||
6070 | sds = rcu_dereference(per_cpu(sd_llc_shared, cpu)); | |
6071 | if (sds) | |
6072 | return READ_ONCE(sds->has_idle_cores); | |
6073 | ||
6074 | return def; | |
6075 | } | |
6076 | ||
6077 | /* | |
6078 | * Scans the local SMT mask to see if the entire core is idle, and records this | |
6079 | * information in sd_llc_shared->has_idle_cores. | |
6080 | * | |
6081 | * Since SMT siblings share all cache levels, inspecting this limited remote | |
6082 | * state should be fairly cheap. | |
6083 | */ | |
1b568f0a | 6084 | void __update_idle_core(struct rq *rq) |
10e2f1ac PZ |
6085 | { |
6086 | int core = cpu_of(rq); | |
6087 | int cpu; | |
6088 | ||
6089 | rcu_read_lock(); | |
6090 | if (test_idle_cores(core, true)) | |
6091 | goto unlock; | |
6092 | ||
6093 | for_each_cpu(cpu, cpu_smt_mask(core)) { | |
6094 | if (cpu == core) | |
6095 | continue; | |
6096 | ||
6097 | if (!idle_cpu(cpu)) | |
6098 | goto unlock; | |
6099 | } | |
6100 | ||
6101 | set_idle_cores(core, 1); | |
6102 | unlock: | |
6103 | rcu_read_unlock(); | |
6104 | } | |
6105 | ||
6106 | /* | |
6107 | * Scan the entire LLC domain for idle cores; this dynamically switches off if | |
6108 | * there are no idle cores left in the system; tracked through | |
6109 | * sd_llc->shared->has_idle_cores and enabled through update_idle_core() above. | |
6110 | */ | |
6111 | static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target) | |
6112 | { | |
6113 | struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask); | |
c743f0a5 | 6114 | int core, cpu; |
10e2f1ac | 6115 | |
1b568f0a PZ |
6116 | if (!static_branch_likely(&sched_smt_present)) |
6117 | return -1; | |
6118 | ||
10e2f1ac PZ |
6119 | if (!test_idle_cores(target, false)) |
6120 | return -1; | |
6121 | ||
0c98d344 | 6122 | cpumask_and(cpus, sched_domain_span(sd), &p->cpus_allowed); |
10e2f1ac | 6123 | |
c743f0a5 | 6124 | for_each_cpu_wrap(core, cpus, target) { |
10e2f1ac PZ |
6125 | bool idle = true; |
6126 | ||
6127 | for_each_cpu(cpu, cpu_smt_mask(core)) { | |
6128 | cpumask_clear_cpu(cpu, cpus); | |
6129 | if (!idle_cpu(cpu)) | |
6130 | idle = false; | |
6131 | } | |
6132 | ||
6133 | if (idle) | |
6134 | return core; | |
6135 | } | |
6136 | ||
6137 | /* | |
6138 | * Failed to find an idle core; stop looking for one. | |
6139 | */ | |
6140 | set_idle_cores(target, 0); | |
6141 | ||
6142 | return -1; | |
6143 | } | |
6144 | ||
6145 | /* | |
6146 | * Scan the local SMT mask for idle CPUs. | |
6147 | */ | |
6148 | static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target) | |
6149 | { | |
6150 | int cpu; | |
6151 | ||
1b568f0a PZ |
6152 | if (!static_branch_likely(&sched_smt_present)) |
6153 | return -1; | |
6154 | ||
10e2f1ac | 6155 | for_each_cpu(cpu, cpu_smt_mask(target)) { |
0c98d344 | 6156 | if (!cpumask_test_cpu(cpu, &p->cpus_allowed)) |
10e2f1ac PZ |
6157 | continue; |
6158 | if (idle_cpu(cpu)) | |
6159 | return cpu; | |
6160 | } | |
6161 | ||
6162 | return -1; | |
6163 | } | |
6164 | ||
6165 | #else /* CONFIG_SCHED_SMT */ | |
6166 | ||
6167 | static inline int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target) | |
6168 | { | |
6169 | return -1; | |
6170 | } | |
6171 | ||
6172 | static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target) | |
6173 | { | |
6174 | return -1; | |
6175 | } | |
6176 | ||
6177 | #endif /* CONFIG_SCHED_SMT */ | |
6178 | ||
6179 | /* | |
6180 | * Scan the LLC domain for idle CPUs; this is dynamically regulated by | |
6181 | * comparing the average scan cost (tracked in sd->avg_scan_cost) against the | |
6182 | * average idle time for this rq (as found in rq->avg_idle). | |
a50bde51 | 6183 | */ |
10e2f1ac PZ |
6184 | static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int target) |
6185 | { | |
9cfb38a7 | 6186 | struct sched_domain *this_sd; |
1ad3aaf3 | 6187 | u64 avg_cost, avg_idle; |
10e2f1ac PZ |
6188 | u64 time, cost; |
6189 | s64 delta; | |
1ad3aaf3 | 6190 | int cpu, nr = INT_MAX; |
10e2f1ac | 6191 | |
9cfb38a7 WL |
6192 | this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc)); |
6193 | if (!this_sd) | |
6194 | return -1; | |
6195 | ||
10e2f1ac PZ |
6196 | /* |
6197 | * Due to large variance we need a large fuzz factor; hackbench in | |
6198 | * particularly is sensitive here. | |
6199 | */ | |
1ad3aaf3 PZ |
6200 | avg_idle = this_rq()->avg_idle / 512; |
6201 | avg_cost = this_sd->avg_scan_cost + 1; | |
6202 | ||
6203 | if (sched_feat(SIS_AVG_CPU) && avg_idle < avg_cost) | |
10e2f1ac PZ |
6204 | return -1; |
6205 | ||
1ad3aaf3 PZ |
6206 | if (sched_feat(SIS_PROP)) { |
6207 | u64 span_avg = sd->span_weight * avg_idle; | |
6208 | if (span_avg > 4*avg_cost) | |
6209 | nr = div_u64(span_avg, avg_cost); | |
6210 | else | |
6211 | nr = 4; | |
6212 | } | |
6213 | ||
10e2f1ac PZ |
6214 | time = local_clock(); |
6215 | ||
c743f0a5 | 6216 | for_each_cpu_wrap(cpu, sched_domain_span(sd), target) { |
1ad3aaf3 PZ |
6217 | if (!--nr) |
6218 | return -1; | |
0c98d344 | 6219 | if (!cpumask_test_cpu(cpu, &p->cpus_allowed)) |
10e2f1ac PZ |
6220 | continue; |
6221 | if (idle_cpu(cpu)) | |
6222 | break; | |
6223 | } | |
6224 | ||
6225 | time = local_clock() - time; | |
6226 | cost = this_sd->avg_scan_cost; | |
6227 | delta = (s64)(time - cost) / 8; | |
6228 | this_sd->avg_scan_cost += delta; | |
6229 | ||
6230 | return cpu; | |
6231 | } | |
6232 | ||
6233 | /* | |
6234 | * Try and locate an idle core/thread in the LLC cache domain. | |
a50bde51 | 6235 | */ |
772bd008 | 6236 | static int select_idle_sibling(struct task_struct *p, int prev, int target) |
a50bde51 | 6237 | { |
99bd5e2f | 6238 | struct sched_domain *sd; |
10e2f1ac | 6239 | int i; |
a50bde51 | 6240 | |
e0a79f52 MG |
6241 | if (idle_cpu(target)) |
6242 | return target; | |
99bd5e2f SS |
6243 | |
6244 | /* | |
10e2f1ac | 6245 | * If the previous cpu is cache affine and idle, don't be stupid. |
99bd5e2f | 6246 | */ |
772bd008 MR |
6247 | if (prev != target && cpus_share_cache(prev, target) && idle_cpu(prev)) |
6248 | return prev; | |
a50bde51 | 6249 | |
518cd623 | 6250 | sd = rcu_dereference(per_cpu(sd_llc, target)); |
10e2f1ac PZ |
6251 | if (!sd) |
6252 | return target; | |
772bd008 | 6253 | |
10e2f1ac PZ |
6254 | i = select_idle_core(p, sd, target); |
6255 | if ((unsigned)i < nr_cpumask_bits) | |
6256 | return i; | |
37407ea7 | 6257 | |
10e2f1ac PZ |
6258 | i = select_idle_cpu(p, sd, target); |
6259 | if ((unsigned)i < nr_cpumask_bits) | |
6260 | return i; | |
6261 | ||
6262 | i = select_idle_smt(p, sd, target); | |
6263 | if ((unsigned)i < nr_cpumask_bits) | |
6264 | return i; | |
970e1789 | 6265 | |
a50bde51 PZ |
6266 | return target; |
6267 | } | |
231678b7 | 6268 | |
8bb5b00c | 6269 | /* |
9e91d61d | 6270 | * cpu_util returns the amount of capacity of a CPU that is used by CFS |
8bb5b00c | 6271 | * tasks. The unit of the return value must be the one of capacity so we can |
9e91d61d DE |
6272 | * compare the utilization with the capacity of the CPU that is available for |
6273 | * CFS task (ie cpu_capacity). | |
231678b7 DE |
6274 | * |
6275 | * cfs_rq.avg.util_avg is the sum of running time of runnable tasks plus the | |
6276 | * recent utilization of currently non-runnable tasks on a CPU. It represents | |
6277 | * the amount of utilization of a CPU in the range [0..capacity_orig] where | |
6278 | * capacity_orig is the cpu_capacity available at the highest frequency | |
6279 | * (arch_scale_freq_capacity()). | |
6280 | * The utilization of a CPU converges towards a sum equal to or less than the | |
6281 | * current capacity (capacity_curr <= capacity_orig) of the CPU because it is | |
6282 | * the running time on this CPU scaled by capacity_curr. | |
6283 | * | |
6284 | * Nevertheless, cfs_rq.avg.util_avg can be higher than capacity_curr or even | |
6285 | * higher than capacity_orig because of unfortunate rounding in | |
6286 | * cfs.avg.util_avg or just after migrating tasks and new task wakeups until | |
6287 | * the average stabilizes with the new running time. We need to check that the | |
6288 | * utilization stays within the range of [0..capacity_orig] and cap it if | |
6289 | * necessary. Without utilization capping, a group could be seen as overloaded | |
6290 | * (CPU0 utilization at 121% + CPU1 utilization at 80%) whereas CPU1 has 20% of | |
6291 | * available capacity. We allow utilization to overshoot capacity_curr (but not | |
6292 | * capacity_orig) as it useful for predicting the capacity required after task | |
6293 | * migrations (scheduler-driven DVFS). | |
8bb5b00c | 6294 | */ |
9e91d61d | 6295 | static int cpu_util(int cpu) |
8bb5b00c | 6296 | { |
9e91d61d | 6297 | unsigned long util = cpu_rq(cpu)->cfs.avg.util_avg; |
8bb5b00c VG |
6298 | unsigned long capacity = capacity_orig_of(cpu); |
6299 | ||
231678b7 | 6300 | return (util >= capacity) ? capacity : util; |
8bb5b00c | 6301 | } |
a50bde51 | 6302 | |
3273163c MR |
6303 | static inline int task_util(struct task_struct *p) |
6304 | { | |
6305 | return p->se.avg.util_avg; | |
6306 | } | |
6307 | ||
104cb16d MR |
6308 | /* |
6309 | * cpu_util_wake: Compute cpu utilization with any contributions from | |
6310 | * the waking task p removed. | |
6311 | */ | |
6312 | static int cpu_util_wake(int cpu, struct task_struct *p) | |
6313 | { | |
6314 | unsigned long util, capacity; | |
6315 | ||
6316 | /* Task has no contribution or is new */ | |
6317 | if (cpu != task_cpu(p) || !p->se.avg.last_update_time) | |
6318 | return cpu_util(cpu); | |
6319 | ||
6320 | capacity = capacity_orig_of(cpu); | |
6321 | util = max_t(long, cpu_rq(cpu)->cfs.avg.util_avg - task_util(p), 0); | |
6322 | ||
6323 | return (util >= capacity) ? capacity : util; | |
6324 | } | |
6325 | ||
3273163c MR |
6326 | /* |
6327 | * Disable WAKE_AFFINE in the case where task @p doesn't fit in the | |
6328 | * capacity of either the waking CPU @cpu or the previous CPU @prev_cpu. | |
6329 | * | |
6330 | * In that case WAKE_AFFINE doesn't make sense and we'll let | |
6331 | * BALANCE_WAKE sort things out. | |
6332 | */ | |
6333 | static int wake_cap(struct task_struct *p, int cpu, int prev_cpu) | |
6334 | { | |
6335 | long min_cap, max_cap; | |
6336 | ||
6337 | min_cap = min(capacity_orig_of(prev_cpu), capacity_orig_of(cpu)); | |
6338 | max_cap = cpu_rq(cpu)->rd->max_cpu_capacity; | |
6339 | ||
6340 | /* Minimum capacity is close to max, no need to abort wake_affine */ | |
6341 | if (max_cap - min_cap < max_cap >> 3) | |
6342 | return 0; | |
6343 | ||
104cb16d MR |
6344 | /* Bring task utilization in sync with prev_cpu */ |
6345 | sync_entity_load_avg(&p->se); | |
6346 | ||
3273163c MR |
6347 | return min_cap * 1024 < task_util(p) * capacity_margin; |
6348 | } | |
6349 | ||
aaee1203 | 6350 | /* |
de91b9cb MR |
6351 | * select_task_rq_fair: Select target runqueue for the waking task in domains |
6352 | * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE, | |
6353 | * SD_BALANCE_FORK, or SD_BALANCE_EXEC. | |
aaee1203 | 6354 | * |
de91b9cb MR |
6355 | * Balances load by selecting the idlest cpu in the idlest group, or under |
6356 | * certain conditions an idle sibling cpu if the domain has SD_WAKE_AFFINE set. | |
aaee1203 | 6357 | * |
de91b9cb | 6358 | * Returns the target cpu number. |
aaee1203 PZ |
6359 | * |
6360 | * preempt must be disabled. | |
6361 | */ | |
0017d735 | 6362 | static int |
ac66f547 | 6363 | select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags) |
aaee1203 | 6364 | { |
29cd8bae | 6365 | struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL; |
c88d5910 | 6366 | int cpu = smp_processor_id(); |
63b0e9ed | 6367 | int new_cpu = prev_cpu; |
99bd5e2f | 6368 | int want_affine = 0; |
5158f4e4 | 6369 | int sync = wake_flags & WF_SYNC; |
c88d5910 | 6370 | |
c58d25f3 PZ |
6371 | if (sd_flag & SD_BALANCE_WAKE) { |
6372 | record_wakee(p); | |
3273163c | 6373 | want_affine = !wake_wide(p) && !wake_cap(p, cpu, prev_cpu) |
0c98d344 | 6374 | && cpumask_test_cpu(cpu, &p->cpus_allowed); |
c58d25f3 | 6375 | } |
aaee1203 | 6376 | |
dce840a0 | 6377 | rcu_read_lock(); |
aaee1203 | 6378 | for_each_domain(cpu, tmp) { |
e4f42888 | 6379 | if (!(tmp->flags & SD_LOAD_BALANCE)) |
63b0e9ed | 6380 | break; |
e4f42888 | 6381 | |
fe3bcfe1 | 6382 | /* |
99bd5e2f SS |
6383 | * If both cpu and prev_cpu are part of this domain, |
6384 | * cpu is a valid SD_WAKE_AFFINE target. | |
fe3bcfe1 | 6385 | */ |
99bd5e2f SS |
6386 | if (want_affine && (tmp->flags & SD_WAKE_AFFINE) && |
6387 | cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) { | |
6388 | affine_sd = tmp; | |
29cd8bae | 6389 | break; |
f03542a7 | 6390 | } |
29cd8bae | 6391 | |
f03542a7 | 6392 | if (tmp->flags & sd_flag) |
29cd8bae | 6393 | sd = tmp; |
63b0e9ed MG |
6394 | else if (!want_affine) |
6395 | break; | |
29cd8bae PZ |
6396 | } |
6397 | ||
63b0e9ed MG |
6398 | if (affine_sd) { |
6399 | sd = NULL; /* Prefer wake_affine over balance flags */ | |
7d894e6e RR |
6400 | if (cpu == prev_cpu) |
6401 | goto pick_cpu; | |
6402 | ||
6403 | if (wake_affine(affine_sd, p, prev_cpu, sync)) | |
63b0e9ed | 6404 | new_cpu = cpu; |
8b911acd | 6405 | } |
e7693a36 | 6406 | |
ea16f0ea BJ |
6407 | if (sd && !(sd_flag & SD_BALANCE_FORK)) { |
6408 | /* | |
6409 | * We're going to need the task's util for capacity_spare_wake | |
6410 | * in find_idlest_group. Sync it up to prev_cpu's | |
6411 | * last_update_time. | |
6412 | */ | |
6413 | sync_entity_load_avg(&p->se); | |
6414 | } | |
6415 | ||
63b0e9ed | 6416 | if (!sd) { |
ea16f0ea | 6417 | pick_cpu: |
63b0e9ed | 6418 | if (sd_flag & SD_BALANCE_WAKE) /* XXX always ? */ |
772bd008 | 6419 | new_cpu = select_idle_sibling(p, prev_cpu, new_cpu); |
63b0e9ed | 6420 | |
18bd1b4b BJ |
6421 | } else { |
6422 | new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag); | |
e7693a36 | 6423 | } |
dce840a0 | 6424 | rcu_read_unlock(); |
e7693a36 | 6425 | |
c88d5910 | 6426 | return new_cpu; |
e7693a36 | 6427 | } |
0a74bef8 | 6428 | |
144d8487 PZ |
6429 | static void detach_entity_cfs_rq(struct sched_entity *se); |
6430 | ||
0a74bef8 PT |
6431 | /* |
6432 | * Called immediately before a task is migrated to a new cpu; task_cpu(p) and | |
6433 | * cfs_rq_of(p) references at time of call are still valid and identify the | |
525628c7 | 6434 | * previous cpu. The caller guarantees p->pi_lock or task_rq(p)->lock is held. |
0a74bef8 | 6435 | */ |
5a4fd036 | 6436 | static void migrate_task_rq_fair(struct task_struct *p) |
0a74bef8 | 6437 | { |
59efa0ba PZ |
6438 | /* |
6439 | * As blocked tasks retain absolute vruntime the migration needs to | |
6440 | * deal with this by subtracting the old and adding the new | |
6441 | * min_vruntime -- the latter is done by enqueue_entity() when placing | |
6442 | * the task on the new runqueue. | |
6443 | */ | |
6444 | if (p->state == TASK_WAKING) { | |
6445 | struct sched_entity *se = &p->se; | |
6446 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
6447 | u64 min_vruntime; | |
6448 | ||
6449 | #ifndef CONFIG_64BIT | |
6450 | u64 min_vruntime_copy; | |
6451 | ||
6452 | do { | |
6453 | min_vruntime_copy = cfs_rq->min_vruntime_copy; | |
6454 | smp_rmb(); | |
6455 | min_vruntime = cfs_rq->min_vruntime; | |
6456 | } while (min_vruntime != min_vruntime_copy); | |
6457 | #else | |
6458 | min_vruntime = cfs_rq->min_vruntime; | |
6459 | #endif | |
6460 | ||
6461 | se->vruntime -= min_vruntime; | |
6462 | } | |
6463 | ||
144d8487 PZ |
6464 | if (p->on_rq == TASK_ON_RQ_MIGRATING) { |
6465 | /* | |
6466 | * In case of TASK_ON_RQ_MIGRATING we in fact hold the 'old' | |
6467 | * rq->lock and can modify state directly. | |
6468 | */ | |
6469 | lockdep_assert_held(&task_rq(p)->lock); | |
6470 | detach_entity_cfs_rq(&p->se); | |
6471 | ||
6472 | } else { | |
6473 | /* | |
6474 | * We are supposed to update the task to "current" time, then | |
6475 | * its up to date and ready to go to new CPU/cfs_rq. But we | |
6476 | * have difficulty in getting what current time is, so simply | |
6477 | * throw away the out-of-date time. This will result in the | |
6478 | * wakee task is less decayed, but giving the wakee more load | |
6479 | * sounds not bad. | |
6480 | */ | |
6481 | remove_entity_load_avg(&p->se); | |
6482 | } | |
9d89c257 YD |
6483 | |
6484 | /* Tell new CPU we are migrated */ | |
6485 | p->se.avg.last_update_time = 0; | |
3944a927 BS |
6486 | |
6487 | /* We have migrated, no longer consider this task hot */ | |
9d89c257 | 6488 | p->se.exec_start = 0; |
0a74bef8 | 6489 | } |
12695578 YD |
6490 | |
6491 | static void task_dead_fair(struct task_struct *p) | |
6492 | { | |
6493 | remove_entity_load_avg(&p->se); | |
6494 | } | |
e7693a36 GH |
6495 | #endif /* CONFIG_SMP */ |
6496 | ||
e52fb7c0 PZ |
6497 | static unsigned long |
6498 | wakeup_gran(struct sched_entity *curr, struct sched_entity *se) | |
0bbd3336 PZ |
6499 | { |
6500 | unsigned long gran = sysctl_sched_wakeup_granularity; | |
6501 | ||
6502 | /* | |
e52fb7c0 PZ |
6503 | * Since its curr running now, convert the gran from real-time |
6504 | * to virtual-time in his units. | |
13814d42 MG |
6505 | * |
6506 | * By using 'se' instead of 'curr' we penalize light tasks, so | |
6507 | * they get preempted easier. That is, if 'se' < 'curr' then | |
6508 | * the resulting gran will be larger, therefore penalizing the | |
6509 | * lighter, if otoh 'se' > 'curr' then the resulting gran will | |
6510 | * be smaller, again penalizing the lighter task. | |
6511 | * | |
6512 | * This is especially important for buddies when the leftmost | |
6513 | * task is higher priority than the buddy. | |
0bbd3336 | 6514 | */ |
f4ad9bd2 | 6515 | return calc_delta_fair(gran, se); |
0bbd3336 PZ |
6516 | } |
6517 | ||
464b7527 PZ |
6518 | /* |
6519 | * Should 'se' preempt 'curr'. | |
6520 | * | |
6521 | * |s1 | |
6522 | * |s2 | |
6523 | * |s3 | |
6524 | * g | |
6525 | * |<--->|c | |
6526 | * | |
6527 | * w(c, s1) = -1 | |
6528 | * w(c, s2) = 0 | |
6529 | * w(c, s3) = 1 | |
6530 | * | |
6531 | */ | |
6532 | static int | |
6533 | wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se) | |
6534 | { | |
6535 | s64 gran, vdiff = curr->vruntime - se->vruntime; | |
6536 | ||
6537 | if (vdiff <= 0) | |
6538 | return -1; | |
6539 | ||
e52fb7c0 | 6540 | gran = wakeup_gran(curr, se); |
464b7527 PZ |
6541 | if (vdiff > gran) |
6542 | return 1; | |
6543 | ||
6544 | return 0; | |
6545 | } | |
6546 | ||
02479099 PZ |
6547 | static void set_last_buddy(struct sched_entity *se) |
6548 | { | |
69c80f3e VP |
6549 | if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
6550 | return; | |
6551 | ||
c5ae366e DA |
6552 | for_each_sched_entity(se) { |
6553 | if (SCHED_WARN_ON(!se->on_rq)) | |
6554 | return; | |
69c80f3e | 6555 | cfs_rq_of(se)->last = se; |
c5ae366e | 6556 | } |
02479099 PZ |
6557 | } |
6558 | ||
6559 | static void set_next_buddy(struct sched_entity *se) | |
6560 | { | |
69c80f3e VP |
6561 | if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
6562 | return; | |
6563 | ||
c5ae366e DA |
6564 | for_each_sched_entity(se) { |
6565 | if (SCHED_WARN_ON(!se->on_rq)) | |
6566 | return; | |
69c80f3e | 6567 | cfs_rq_of(se)->next = se; |
c5ae366e | 6568 | } |
02479099 PZ |
6569 | } |
6570 | ||
ac53db59 RR |
6571 | static void set_skip_buddy(struct sched_entity *se) |
6572 | { | |
69c80f3e VP |
6573 | for_each_sched_entity(se) |
6574 | cfs_rq_of(se)->skip = se; | |
ac53db59 RR |
6575 | } |
6576 | ||
bf0f6f24 IM |
6577 | /* |
6578 | * Preempt the current task with a newly woken task if needed: | |
6579 | */ | |
5a9b86f6 | 6580 | static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) |
bf0f6f24 IM |
6581 | { |
6582 | struct task_struct *curr = rq->curr; | |
8651a86c | 6583 | struct sched_entity *se = &curr->se, *pse = &p->se; |
03e89e45 | 6584 | struct cfs_rq *cfs_rq = task_cfs_rq(curr); |
f685ceac | 6585 | int scale = cfs_rq->nr_running >= sched_nr_latency; |
2f36825b | 6586 | int next_buddy_marked = 0; |
bf0f6f24 | 6587 | |
4ae7d5ce IM |
6588 | if (unlikely(se == pse)) |
6589 | return; | |
6590 | ||
5238cdd3 | 6591 | /* |
163122b7 | 6592 | * This is possible from callers such as attach_tasks(), in which we |
5238cdd3 PT |
6593 | * unconditionally check_prempt_curr() after an enqueue (which may have |
6594 | * lead to a throttle). This both saves work and prevents false | |
6595 | * next-buddy nomination below. | |
6596 | */ | |
6597 | if (unlikely(throttled_hierarchy(cfs_rq_of(pse)))) | |
6598 | return; | |
6599 | ||
2f36825b | 6600 | if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) { |
3cb63d52 | 6601 | set_next_buddy(pse); |
2f36825b VP |
6602 | next_buddy_marked = 1; |
6603 | } | |
57fdc26d | 6604 | |
aec0a514 BR |
6605 | /* |
6606 | * We can come here with TIF_NEED_RESCHED already set from new task | |
6607 | * wake up path. | |
5238cdd3 PT |
6608 | * |
6609 | * Note: this also catches the edge-case of curr being in a throttled | |
6610 | * group (e.g. via set_curr_task), since update_curr() (in the | |
6611 | * enqueue of curr) will have resulted in resched being set. This | |
6612 | * prevents us from potentially nominating it as a false LAST_BUDDY | |
6613 | * below. | |
aec0a514 BR |
6614 | */ |
6615 | if (test_tsk_need_resched(curr)) | |
6616 | return; | |
6617 | ||
a2f5c9ab DH |
6618 | /* Idle tasks are by definition preempted by non-idle tasks. */ |
6619 | if (unlikely(curr->policy == SCHED_IDLE) && | |
6620 | likely(p->policy != SCHED_IDLE)) | |
6621 | goto preempt; | |
6622 | ||
91c234b4 | 6623 | /* |
a2f5c9ab DH |
6624 | * Batch and idle tasks do not preempt non-idle tasks (their preemption |
6625 | * is driven by the tick): | |
91c234b4 | 6626 | */ |
8ed92e51 | 6627 | if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION)) |
91c234b4 | 6628 | return; |
bf0f6f24 | 6629 | |
464b7527 | 6630 | find_matching_se(&se, &pse); |
9bbd7374 | 6631 | update_curr(cfs_rq_of(se)); |
002f128b | 6632 | BUG_ON(!pse); |
2f36825b VP |
6633 | if (wakeup_preempt_entity(se, pse) == 1) { |
6634 | /* | |
6635 | * Bias pick_next to pick the sched entity that is | |
6636 | * triggering this preemption. | |
6637 | */ | |
6638 | if (!next_buddy_marked) | |
6639 | set_next_buddy(pse); | |
3a7e73a2 | 6640 | goto preempt; |
2f36825b | 6641 | } |
464b7527 | 6642 | |
3a7e73a2 | 6643 | return; |
a65ac745 | 6644 | |
3a7e73a2 | 6645 | preempt: |
8875125e | 6646 | resched_curr(rq); |
3a7e73a2 PZ |
6647 | /* |
6648 | * Only set the backward buddy when the current task is still | |
6649 | * on the rq. This can happen when a wakeup gets interleaved | |
6650 | * with schedule on the ->pre_schedule() or idle_balance() | |
6651 | * point, either of which can * drop the rq lock. | |
6652 | * | |
6653 | * Also, during early boot the idle thread is in the fair class, | |
6654 | * for obvious reasons its a bad idea to schedule back to it. | |
6655 | */ | |
6656 | if (unlikely(!se->on_rq || curr == rq->idle)) | |
6657 | return; | |
6658 | ||
6659 | if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se)) | |
6660 | set_last_buddy(se); | |
bf0f6f24 IM |
6661 | } |
6662 | ||
606dba2e | 6663 | static struct task_struct * |
d8ac8971 | 6664 | pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) |
bf0f6f24 IM |
6665 | { |
6666 | struct cfs_rq *cfs_rq = &rq->cfs; | |
6667 | struct sched_entity *se; | |
678d5718 | 6668 | struct task_struct *p; |
37e117c0 | 6669 | int new_tasks; |
678d5718 | 6670 | |
6e83125c | 6671 | again: |
678d5718 | 6672 | if (!cfs_rq->nr_running) |
38033c37 | 6673 | goto idle; |
678d5718 | 6674 | |
9674f5ca | 6675 | #ifdef CONFIG_FAIR_GROUP_SCHED |
3f1d2a31 | 6676 | if (prev->sched_class != &fair_sched_class) |
678d5718 PZ |
6677 | goto simple; |
6678 | ||
6679 | /* | |
6680 | * Because of the set_next_buddy() in dequeue_task_fair() it is rather | |
6681 | * likely that a next task is from the same cgroup as the current. | |
6682 | * | |
6683 | * Therefore attempt to avoid putting and setting the entire cgroup | |
6684 | * hierarchy, only change the part that actually changes. | |
6685 | */ | |
6686 | ||
6687 | do { | |
6688 | struct sched_entity *curr = cfs_rq->curr; | |
6689 | ||
6690 | /* | |
6691 | * Since we got here without doing put_prev_entity() we also | |
6692 | * have to consider cfs_rq->curr. If it is still a runnable | |
6693 | * entity, update_curr() will update its vruntime, otherwise | |
6694 | * forget we've ever seen it. | |
6695 | */ | |
54d27365 BS |
6696 | if (curr) { |
6697 | if (curr->on_rq) | |
6698 | update_curr(cfs_rq); | |
6699 | else | |
6700 | curr = NULL; | |
678d5718 | 6701 | |
54d27365 BS |
6702 | /* |
6703 | * This call to check_cfs_rq_runtime() will do the | |
6704 | * throttle and dequeue its entity in the parent(s). | |
9674f5ca | 6705 | * Therefore the nr_running test will indeed |
54d27365 BS |
6706 | * be correct. |
6707 | */ | |
9674f5ca VK |
6708 | if (unlikely(check_cfs_rq_runtime(cfs_rq))) { |
6709 | cfs_rq = &rq->cfs; | |
6710 | ||
6711 | if (!cfs_rq->nr_running) | |
6712 | goto idle; | |
6713 | ||
54d27365 | 6714 | goto simple; |
9674f5ca | 6715 | } |
54d27365 | 6716 | } |
678d5718 PZ |
6717 | |
6718 | se = pick_next_entity(cfs_rq, curr); | |
6719 | cfs_rq = group_cfs_rq(se); | |
6720 | } while (cfs_rq); | |
6721 | ||
6722 | p = task_of(se); | |
6723 | ||
6724 | /* | |
6725 | * Since we haven't yet done put_prev_entity and if the selected task | |
6726 | * is a different task than we started out with, try and touch the | |
6727 | * least amount of cfs_rqs. | |
6728 | */ | |
6729 | if (prev != p) { | |
6730 | struct sched_entity *pse = &prev->se; | |
6731 | ||
6732 | while (!(cfs_rq = is_same_group(se, pse))) { | |
6733 | int se_depth = se->depth; | |
6734 | int pse_depth = pse->depth; | |
6735 | ||
6736 | if (se_depth <= pse_depth) { | |
6737 | put_prev_entity(cfs_rq_of(pse), pse); | |
6738 | pse = parent_entity(pse); | |
6739 | } | |
6740 | if (se_depth >= pse_depth) { | |
6741 | set_next_entity(cfs_rq_of(se), se); | |
6742 | se = parent_entity(se); | |
6743 | } | |
6744 | } | |
6745 | ||
6746 | put_prev_entity(cfs_rq, pse); | |
6747 | set_next_entity(cfs_rq, se); | |
6748 | } | |
6749 | ||
93824900 | 6750 | goto done; |
678d5718 | 6751 | simple: |
678d5718 | 6752 | #endif |
bf0f6f24 | 6753 | |
3f1d2a31 | 6754 | put_prev_task(rq, prev); |
606dba2e | 6755 | |
bf0f6f24 | 6756 | do { |
678d5718 | 6757 | se = pick_next_entity(cfs_rq, NULL); |
f4b6755f | 6758 | set_next_entity(cfs_rq, se); |
bf0f6f24 IM |
6759 | cfs_rq = group_cfs_rq(se); |
6760 | } while (cfs_rq); | |
6761 | ||
8f4d37ec | 6762 | p = task_of(se); |
678d5718 | 6763 | |
93824900 UR |
6764 | done: __maybe_unused |
6765 | #ifdef CONFIG_SMP | |
6766 | /* | |
6767 | * Move the next running task to the front of | |
6768 | * the list, so our cfs_tasks list becomes MRU | |
6769 | * one. | |
6770 | */ | |
6771 | list_move(&p->se.group_node, &rq->cfs_tasks); | |
6772 | #endif | |
6773 | ||
b39e66ea MG |
6774 | if (hrtick_enabled(rq)) |
6775 | hrtick_start_fair(rq, p); | |
8f4d37ec PZ |
6776 | |
6777 | return p; | |
38033c37 PZ |
6778 | |
6779 | idle: | |
46f69fa3 MF |
6780 | new_tasks = idle_balance(rq, rf); |
6781 | ||
37e117c0 PZ |
6782 | /* |
6783 | * Because idle_balance() releases (and re-acquires) rq->lock, it is | |
6784 | * possible for any higher priority task to appear. In that case we | |
6785 | * must re-start the pick_next_entity() loop. | |
6786 | */ | |
e4aa358b | 6787 | if (new_tasks < 0) |
37e117c0 PZ |
6788 | return RETRY_TASK; |
6789 | ||
e4aa358b | 6790 | if (new_tasks > 0) |
38033c37 | 6791 | goto again; |
38033c37 PZ |
6792 | |
6793 | return NULL; | |
bf0f6f24 IM |
6794 | } |
6795 | ||
6796 | /* | |
6797 | * Account for a descheduled task: | |
6798 | */ | |
31ee529c | 6799 | static void put_prev_task_fair(struct rq *rq, struct task_struct *prev) |
bf0f6f24 IM |
6800 | { |
6801 | struct sched_entity *se = &prev->se; | |
6802 | struct cfs_rq *cfs_rq; | |
6803 | ||
6804 | for_each_sched_entity(se) { | |
6805 | cfs_rq = cfs_rq_of(se); | |
ab6cde26 | 6806 | put_prev_entity(cfs_rq, se); |
bf0f6f24 IM |
6807 | } |
6808 | } | |
6809 | ||
ac53db59 RR |
6810 | /* |
6811 | * sched_yield() is very simple | |
6812 | * | |
6813 | * The magic of dealing with the ->skip buddy is in pick_next_entity. | |
6814 | */ | |
6815 | static void yield_task_fair(struct rq *rq) | |
6816 | { | |
6817 | struct task_struct *curr = rq->curr; | |
6818 | struct cfs_rq *cfs_rq = task_cfs_rq(curr); | |
6819 | struct sched_entity *se = &curr->se; | |
6820 | ||
6821 | /* | |
6822 | * Are we the only task in the tree? | |
6823 | */ | |
6824 | if (unlikely(rq->nr_running == 1)) | |
6825 | return; | |
6826 | ||
6827 | clear_buddies(cfs_rq, se); | |
6828 | ||
6829 | if (curr->policy != SCHED_BATCH) { | |
6830 | update_rq_clock(rq); | |
6831 | /* | |
6832 | * Update run-time statistics of the 'current'. | |
6833 | */ | |
6834 | update_curr(cfs_rq); | |
916671c0 MG |
6835 | /* |
6836 | * Tell update_rq_clock() that we've just updated, | |
6837 | * so we don't do microscopic update in schedule() | |
6838 | * and double the fastpath cost. | |
6839 | */ | |
9edfbfed | 6840 | rq_clock_skip_update(rq, true); |
ac53db59 RR |
6841 | } |
6842 | ||
6843 | set_skip_buddy(se); | |
6844 | } | |
6845 | ||
d95f4122 MG |
6846 | static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt) |
6847 | { | |
6848 | struct sched_entity *se = &p->se; | |
6849 | ||
5238cdd3 PT |
6850 | /* throttled hierarchies are not runnable */ |
6851 | if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se))) | |
d95f4122 MG |
6852 | return false; |
6853 | ||
6854 | /* Tell the scheduler that we'd really like pse to run next. */ | |
6855 | set_next_buddy(se); | |
6856 | ||
d95f4122 MG |
6857 | yield_task_fair(rq); |
6858 | ||
6859 | return true; | |
6860 | } | |
6861 | ||
681f3e68 | 6862 | #ifdef CONFIG_SMP |
bf0f6f24 | 6863 | /************************************************** |
e9c84cb8 PZ |
6864 | * Fair scheduling class load-balancing methods. |
6865 | * | |
6866 | * BASICS | |
6867 | * | |
6868 | * The purpose of load-balancing is to achieve the same basic fairness the | |
6869 | * per-cpu scheduler provides, namely provide a proportional amount of compute | |
6870 | * time to each task. This is expressed in the following equation: | |
6871 | * | |
6872 | * W_i,n/P_i == W_j,n/P_j for all i,j (1) | |
6873 | * | |
6874 | * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight | |
6875 | * W_i,0 is defined as: | |
6876 | * | |
6877 | * W_i,0 = \Sum_j w_i,j (2) | |
6878 | * | |
6879 | * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight | |
1c3de5e1 | 6880 | * is derived from the nice value as per sched_prio_to_weight[]. |
e9c84cb8 PZ |
6881 | * |
6882 | * The weight average is an exponential decay average of the instantaneous | |
6883 | * weight: | |
6884 | * | |
6885 | * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3) | |
6886 | * | |
ced549fa | 6887 | * C_i is the compute capacity of cpu i, typically it is the |
e9c84cb8 PZ |
6888 | * fraction of 'recent' time available for SCHED_OTHER task execution. But it |
6889 | * can also include other factors [XXX]. | |
6890 | * | |
6891 | * To achieve this balance we define a measure of imbalance which follows | |
6892 | * directly from (1): | |
6893 | * | |
ced549fa | 6894 | * imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j } (4) |
e9c84cb8 PZ |
6895 | * |
6896 | * We them move tasks around to minimize the imbalance. In the continuous | |
6897 | * function space it is obvious this converges, in the discrete case we get | |
6898 | * a few fun cases generally called infeasible weight scenarios. | |
6899 | * | |
6900 | * [XXX expand on: | |
6901 | * - infeasible weights; | |
6902 | * - local vs global optima in the discrete case. ] | |
6903 | * | |
6904 | * | |
6905 | * SCHED DOMAINS | |
6906 | * | |
6907 | * In order to solve the imbalance equation (4), and avoid the obvious O(n^2) | |
6908 | * for all i,j solution, we create a tree of cpus that follows the hardware | |
6909 | * topology where each level pairs two lower groups (or better). This results | |
6910 | * in O(log n) layers. Furthermore we reduce the number of cpus going up the | |
6911 | * tree to only the first of the previous level and we decrease the frequency | |
6912 | * of load-balance at each level inv. proportional to the number of cpus in | |
6913 | * the groups. | |
6914 | * | |
6915 | * This yields: | |
6916 | * | |
6917 | * log_2 n 1 n | |
6918 | * \Sum { --- * --- * 2^i } = O(n) (5) | |
6919 | * i = 0 2^i 2^i | |
6920 | * `- size of each group | |
6921 | * | | `- number of cpus doing load-balance | |
6922 | * | `- freq | |
6923 | * `- sum over all levels | |
6924 | * | |
6925 | * Coupled with a limit on how many tasks we can migrate every balance pass, | |
6926 | * this makes (5) the runtime complexity of the balancer. | |
6927 | * | |
6928 | * An important property here is that each CPU is still (indirectly) connected | |
6929 | * to every other cpu in at most O(log n) steps: | |
6930 | * | |
6931 | * The adjacency matrix of the resulting graph is given by: | |
6932 | * | |
97a7142f | 6933 | * log_2 n |
e9c84cb8 PZ |
6934 | * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6) |
6935 | * k = 0 | |
6936 | * | |
6937 | * And you'll find that: | |
6938 | * | |
6939 | * A^(log_2 n)_i,j != 0 for all i,j (7) | |
6940 | * | |
6941 | * Showing there's indeed a path between every cpu in at most O(log n) steps. | |
6942 | * The task movement gives a factor of O(m), giving a convergence complexity | |
6943 | * of: | |
6944 | * | |
6945 | * O(nm log n), n := nr_cpus, m := nr_tasks (8) | |
6946 | * | |
6947 | * | |
6948 | * WORK CONSERVING | |
6949 | * | |
6950 | * In order to avoid CPUs going idle while there's still work to do, new idle | |
6951 | * balancing is more aggressive and has the newly idle cpu iterate up the domain | |
6952 | * tree itself instead of relying on other CPUs to bring it work. | |
6953 | * | |
6954 | * This adds some complexity to both (5) and (8) but it reduces the total idle | |
6955 | * time. | |
6956 | * | |
6957 | * [XXX more?] | |
6958 | * | |
6959 | * | |
6960 | * CGROUPS | |
6961 | * | |
6962 | * Cgroups make a horror show out of (2), instead of a simple sum we get: | |
6963 | * | |
6964 | * s_k,i | |
6965 | * W_i,0 = \Sum_j \Prod_k w_k * ----- (9) | |
6966 | * S_k | |
6967 | * | |
6968 | * Where | |
6969 | * | |
6970 | * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10) | |
6971 | * | |
6972 | * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i. | |
6973 | * | |
6974 | * The big problem is S_k, its a global sum needed to compute a local (W_i) | |
6975 | * property. | |
6976 | * | |
6977 | * [XXX write more on how we solve this.. _after_ merging pjt's patches that | |
6978 | * rewrite all of this once again.] | |
97a7142f | 6979 | */ |
bf0f6f24 | 6980 | |
ed387b78 HS |
6981 | static unsigned long __read_mostly max_load_balance_interval = HZ/10; |
6982 | ||
0ec8aa00 PZ |
6983 | enum fbq_type { regular, remote, all }; |
6984 | ||
ddcdf6e7 | 6985 | #define LBF_ALL_PINNED 0x01 |
367456c7 | 6986 | #define LBF_NEED_BREAK 0x02 |
6263322c PZ |
6987 | #define LBF_DST_PINNED 0x04 |
6988 | #define LBF_SOME_PINNED 0x08 | |
ddcdf6e7 PZ |
6989 | |
6990 | struct lb_env { | |
6991 | struct sched_domain *sd; | |
6992 | ||
ddcdf6e7 | 6993 | struct rq *src_rq; |
85c1e7da | 6994 | int src_cpu; |
ddcdf6e7 PZ |
6995 | |
6996 | int dst_cpu; | |
6997 | struct rq *dst_rq; | |
6998 | ||
88b8dac0 SV |
6999 | struct cpumask *dst_grpmask; |
7000 | int new_dst_cpu; | |
ddcdf6e7 | 7001 | enum cpu_idle_type idle; |
bd939f45 | 7002 | long imbalance; |
b9403130 MW |
7003 | /* The set of CPUs under consideration for load-balancing */ |
7004 | struct cpumask *cpus; | |
7005 | ||
ddcdf6e7 | 7006 | unsigned int flags; |
367456c7 PZ |
7007 | |
7008 | unsigned int loop; | |
7009 | unsigned int loop_break; | |
7010 | unsigned int loop_max; | |
0ec8aa00 PZ |
7011 | |
7012 | enum fbq_type fbq_type; | |
163122b7 | 7013 | struct list_head tasks; |
ddcdf6e7 PZ |
7014 | }; |
7015 | ||
029632fb PZ |
7016 | /* |
7017 | * Is this task likely cache-hot: | |
7018 | */ | |
5d5e2b1b | 7019 | static int task_hot(struct task_struct *p, struct lb_env *env) |
029632fb PZ |
7020 | { |
7021 | s64 delta; | |
7022 | ||
e5673f28 KT |
7023 | lockdep_assert_held(&env->src_rq->lock); |
7024 | ||
029632fb PZ |
7025 | if (p->sched_class != &fair_sched_class) |
7026 | return 0; | |
7027 | ||
7028 | if (unlikely(p->policy == SCHED_IDLE)) | |
7029 | return 0; | |
7030 | ||
7031 | /* | |
7032 | * Buddy candidates are cache hot: | |
7033 | */ | |
5d5e2b1b | 7034 | if (sched_feat(CACHE_HOT_BUDDY) && env->dst_rq->nr_running && |
029632fb PZ |
7035 | (&p->se == cfs_rq_of(&p->se)->next || |
7036 | &p->se == cfs_rq_of(&p->se)->last)) | |
7037 | return 1; | |
7038 | ||
7039 | if (sysctl_sched_migration_cost == -1) | |
7040 | return 1; | |
7041 | if (sysctl_sched_migration_cost == 0) | |
7042 | return 0; | |
7043 | ||
5d5e2b1b | 7044 | delta = rq_clock_task(env->src_rq) - p->se.exec_start; |
029632fb PZ |
7045 | |
7046 | return delta < (s64)sysctl_sched_migration_cost; | |
7047 | } | |
7048 | ||
3a7053b3 | 7049 | #ifdef CONFIG_NUMA_BALANCING |
c1ceac62 | 7050 | /* |
2a1ed24c SD |
7051 | * Returns 1, if task migration degrades locality |
7052 | * Returns 0, if task migration improves locality i.e migration preferred. | |
7053 | * Returns -1, if task migration is not affected by locality. | |
c1ceac62 | 7054 | */ |
2a1ed24c | 7055 | static int migrate_degrades_locality(struct task_struct *p, struct lb_env *env) |
3a7053b3 | 7056 | { |
b1ad065e | 7057 | struct numa_group *numa_group = rcu_dereference(p->numa_group); |
c1ceac62 | 7058 | unsigned long src_faults, dst_faults; |
3a7053b3 MG |
7059 | int src_nid, dst_nid; |
7060 | ||
2a595721 | 7061 | if (!static_branch_likely(&sched_numa_balancing)) |
2a1ed24c SD |
7062 | return -1; |
7063 | ||
c3b9bc5b | 7064 | if (!p->numa_faults || !(env->sd->flags & SD_NUMA)) |
2a1ed24c | 7065 | return -1; |
7a0f3083 MG |
7066 | |
7067 | src_nid = cpu_to_node(env->src_cpu); | |
7068 | dst_nid = cpu_to_node(env->dst_cpu); | |
7069 | ||
83e1d2cd | 7070 | if (src_nid == dst_nid) |
2a1ed24c | 7071 | return -1; |
7a0f3083 | 7072 | |
2a1ed24c SD |
7073 | /* Migrating away from the preferred node is always bad. */ |
7074 | if (src_nid == p->numa_preferred_nid) { | |
7075 | if (env->src_rq->nr_running > env->src_rq->nr_preferred_running) | |
7076 | return 1; | |
7077 | else | |
7078 | return -1; | |
7079 | } | |
b1ad065e | 7080 | |
c1ceac62 RR |
7081 | /* Encourage migration to the preferred node. */ |
7082 | if (dst_nid == p->numa_preferred_nid) | |
2a1ed24c | 7083 | return 0; |
b1ad065e | 7084 | |
739294fb RR |
7085 | /* Leaving a core idle is often worse than degrading locality. */ |
7086 | if (env->idle != CPU_NOT_IDLE) | |
7087 | return -1; | |
7088 | ||
c1ceac62 RR |
7089 | if (numa_group) { |
7090 | src_faults = group_faults(p, src_nid); | |
7091 | dst_faults = group_faults(p, dst_nid); | |
7092 | } else { | |
7093 | src_faults = task_faults(p, src_nid); | |
7094 | dst_faults = task_faults(p, dst_nid); | |
b1ad065e RR |
7095 | } |
7096 | ||
c1ceac62 | 7097 | return dst_faults < src_faults; |
7a0f3083 MG |
7098 | } |
7099 | ||
3a7053b3 | 7100 | #else |
2a1ed24c | 7101 | static inline int migrate_degrades_locality(struct task_struct *p, |
3a7053b3 MG |
7102 | struct lb_env *env) |
7103 | { | |
2a1ed24c | 7104 | return -1; |
7a0f3083 | 7105 | } |
3a7053b3 MG |
7106 | #endif |
7107 | ||
1e3c88bd PZ |
7108 | /* |
7109 | * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? | |
7110 | */ | |
7111 | static | |
8e45cb54 | 7112 | int can_migrate_task(struct task_struct *p, struct lb_env *env) |
1e3c88bd | 7113 | { |
2a1ed24c | 7114 | int tsk_cache_hot; |
e5673f28 KT |
7115 | |
7116 | lockdep_assert_held(&env->src_rq->lock); | |
7117 | ||
1e3c88bd PZ |
7118 | /* |
7119 | * We do not migrate tasks that are: | |
d3198084 | 7120 | * 1) throttled_lb_pair, or |
1e3c88bd | 7121 | * 2) cannot be migrated to this CPU due to cpus_allowed, or |
d3198084 JK |
7122 | * 3) running (obviously), or |
7123 | * 4) are cache-hot on their current CPU. | |
1e3c88bd | 7124 | */ |
d3198084 JK |
7125 | if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu)) |
7126 | return 0; | |
7127 | ||
0c98d344 | 7128 | if (!cpumask_test_cpu(env->dst_cpu, &p->cpus_allowed)) { |
e02e60c1 | 7129 | int cpu; |
88b8dac0 | 7130 | |
ae92882e | 7131 | schedstat_inc(p->se.statistics.nr_failed_migrations_affine); |
88b8dac0 | 7132 | |
6263322c PZ |
7133 | env->flags |= LBF_SOME_PINNED; |
7134 | ||
88b8dac0 SV |
7135 | /* |
7136 | * Remember if this task can be migrated to any other cpu in | |
7137 | * our sched_group. We may want to revisit it if we couldn't | |
7138 | * meet load balance goals by pulling other tasks on src_cpu. | |
7139 | * | |
65a4433a JH |
7140 | * Avoid computing new_dst_cpu for NEWLY_IDLE or if we have |
7141 | * already computed one in current iteration. | |
88b8dac0 | 7142 | */ |
65a4433a | 7143 | if (env->idle == CPU_NEWLY_IDLE || (env->flags & LBF_DST_PINNED)) |
88b8dac0 SV |
7144 | return 0; |
7145 | ||
e02e60c1 JK |
7146 | /* Prevent to re-select dst_cpu via env's cpus */ |
7147 | for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) { | |
0c98d344 | 7148 | if (cpumask_test_cpu(cpu, &p->cpus_allowed)) { |
6263322c | 7149 | env->flags |= LBF_DST_PINNED; |
e02e60c1 JK |
7150 | env->new_dst_cpu = cpu; |
7151 | break; | |
7152 | } | |
88b8dac0 | 7153 | } |
e02e60c1 | 7154 | |
1e3c88bd PZ |
7155 | return 0; |
7156 | } | |
88b8dac0 SV |
7157 | |
7158 | /* Record that we found atleast one task that could run on dst_cpu */ | |
8e45cb54 | 7159 | env->flags &= ~LBF_ALL_PINNED; |
1e3c88bd | 7160 | |
ddcdf6e7 | 7161 | if (task_running(env->src_rq, p)) { |
ae92882e | 7162 | schedstat_inc(p->se.statistics.nr_failed_migrations_running); |
1e3c88bd PZ |
7163 | return 0; |
7164 | } | |
7165 | ||
7166 | /* | |
7167 | * Aggressive migration if: | |
3a7053b3 MG |
7168 | * 1) destination numa is preferred |
7169 | * 2) task is cache cold, or | |
7170 | * 3) too many balance attempts have failed. | |
1e3c88bd | 7171 | */ |
2a1ed24c SD |
7172 | tsk_cache_hot = migrate_degrades_locality(p, env); |
7173 | if (tsk_cache_hot == -1) | |
7174 | tsk_cache_hot = task_hot(p, env); | |
3a7053b3 | 7175 | |
2a1ed24c | 7176 | if (tsk_cache_hot <= 0 || |
7a96c231 | 7177 | env->sd->nr_balance_failed > env->sd->cache_nice_tries) { |
2a1ed24c | 7178 | if (tsk_cache_hot == 1) { |
ae92882e JP |
7179 | schedstat_inc(env->sd->lb_hot_gained[env->idle]); |
7180 | schedstat_inc(p->se.statistics.nr_forced_migrations); | |
3a7053b3 | 7181 | } |
1e3c88bd PZ |
7182 | return 1; |
7183 | } | |
7184 | ||
ae92882e | 7185 | schedstat_inc(p->se.statistics.nr_failed_migrations_hot); |
4e2dcb73 | 7186 | return 0; |
1e3c88bd PZ |
7187 | } |
7188 | ||
897c395f | 7189 | /* |
163122b7 KT |
7190 | * detach_task() -- detach the task for the migration specified in env |
7191 | */ | |
7192 | static void detach_task(struct task_struct *p, struct lb_env *env) | |
7193 | { | |
7194 | lockdep_assert_held(&env->src_rq->lock); | |
7195 | ||
163122b7 | 7196 | p->on_rq = TASK_ON_RQ_MIGRATING; |
5704ac0a | 7197 | deactivate_task(env->src_rq, p, DEQUEUE_NOCLOCK); |
163122b7 KT |
7198 | set_task_cpu(p, env->dst_cpu); |
7199 | } | |
7200 | ||
897c395f | 7201 | /* |
e5673f28 | 7202 | * detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as |
897c395f | 7203 | * part of active balancing operations within "domain". |
897c395f | 7204 | * |
e5673f28 | 7205 | * Returns a task if successful and NULL otherwise. |
897c395f | 7206 | */ |
e5673f28 | 7207 | static struct task_struct *detach_one_task(struct lb_env *env) |
897c395f | 7208 | { |
93824900 | 7209 | struct task_struct *p; |
897c395f | 7210 | |
e5673f28 KT |
7211 | lockdep_assert_held(&env->src_rq->lock); |
7212 | ||
93824900 UR |
7213 | list_for_each_entry_reverse(p, |
7214 | &env->src_rq->cfs_tasks, se.group_node) { | |
367456c7 PZ |
7215 | if (!can_migrate_task(p, env)) |
7216 | continue; | |
897c395f | 7217 | |
163122b7 | 7218 | detach_task(p, env); |
e5673f28 | 7219 | |
367456c7 | 7220 | /* |
e5673f28 | 7221 | * Right now, this is only the second place where |
163122b7 | 7222 | * lb_gained[env->idle] is updated (other is detach_tasks) |
e5673f28 | 7223 | * so we can safely collect stats here rather than |
163122b7 | 7224 | * inside detach_tasks(). |
367456c7 | 7225 | */ |
ae92882e | 7226 | schedstat_inc(env->sd->lb_gained[env->idle]); |
e5673f28 | 7227 | return p; |
897c395f | 7228 | } |
e5673f28 | 7229 | return NULL; |
897c395f PZ |
7230 | } |
7231 | ||
eb95308e PZ |
7232 | static const unsigned int sched_nr_migrate_break = 32; |
7233 | ||
5d6523eb | 7234 | /* |
163122b7 KT |
7235 | * detach_tasks() -- tries to detach up to imbalance weighted load from |
7236 | * busiest_rq, as part of a balancing operation within domain "sd". | |
5d6523eb | 7237 | * |
163122b7 | 7238 | * Returns number of detached tasks if successful and 0 otherwise. |
5d6523eb | 7239 | */ |
163122b7 | 7240 | static int detach_tasks(struct lb_env *env) |
1e3c88bd | 7241 | { |
5d6523eb PZ |
7242 | struct list_head *tasks = &env->src_rq->cfs_tasks; |
7243 | struct task_struct *p; | |
367456c7 | 7244 | unsigned long load; |
163122b7 KT |
7245 | int detached = 0; |
7246 | ||
7247 | lockdep_assert_held(&env->src_rq->lock); | |
1e3c88bd | 7248 | |
bd939f45 | 7249 | if (env->imbalance <= 0) |
5d6523eb | 7250 | return 0; |
1e3c88bd | 7251 | |
5d6523eb | 7252 | while (!list_empty(tasks)) { |
985d3a4c YD |
7253 | /* |
7254 | * We don't want to steal all, otherwise we may be treated likewise, | |
7255 | * which could at worst lead to a livelock crash. | |
7256 | */ | |
7257 | if (env->idle != CPU_NOT_IDLE && env->src_rq->nr_running <= 1) | |
7258 | break; | |
7259 | ||
93824900 | 7260 | p = list_last_entry(tasks, struct task_struct, se.group_node); |
1e3c88bd | 7261 | |
367456c7 PZ |
7262 | env->loop++; |
7263 | /* We've more or less seen every task there is, call it quits */ | |
5d6523eb | 7264 | if (env->loop > env->loop_max) |
367456c7 | 7265 | break; |
5d6523eb PZ |
7266 | |
7267 | /* take a breather every nr_migrate tasks */ | |
367456c7 | 7268 | if (env->loop > env->loop_break) { |
eb95308e | 7269 | env->loop_break += sched_nr_migrate_break; |
8e45cb54 | 7270 | env->flags |= LBF_NEED_BREAK; |
ee00e66f | 7271 | break; |
a195f004 | 7272 | } |
1e3c88bd | 7273 | |
d3198084 | 7274 | if (!can_migrate_task(p, env)) |
367456c7 PZ |
7275 | goto next; |
7276 | ||
7277 | load = task_h_load(p); | |
5d6523eb | 7278 | |
eb95308e | 7279 | if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed) |
367456c7 PZ |
7280 | goto next; |
7281 | ||
bd939f45 | 7282 | if ((load / 2) > env->imbalance) |
367456c7 | 7283 | goto next; |
1e3c88bd | 7284 | |
163122b7 KT |
7285 | detach_task(p, env); |
7286 | list_add(&p->se.group_node, &env->tasks); | |
7287 | ||
7288 | detached++; | |
bd939f45 | 7289 | env->imbalance -= load; |
1e3c88bd PZ |
7290 | |
7291 | #ifdef CONFIG_PREEMPT | |
ee00e66f PZ |
7292 | /* |
7293 | * NEWIDLE balancing is a source of latency, so preemptible | |
163122b7 | 7294 | * kernels will stop after the first task is detached to minimize |
ee00e66f PZ |
7295 | * the critical section. |
7296 | */ | |
5d6523eb | 7297 | if (env->idle == CPU_NEWLY_IDLE) |
ee00e66f | 7298 | break; |
1e3c88bd PZ |
7299 | #endif |
7300 | ||
ee00e66f PZ |
7301 | /* |
7302 | * We only want to steal up to the prescribed amount of | |
7303 | * weighted load. | |
7304 | */ | |
bd939f45 | 7305 | if (env->imbalance <= 0) |
ee00e66f | 7306 | break; |
367456c7 PZ |
7307 | |
7308 | continue; | |
7309 | next: | |
93824900 | 7310 | list_move(&p->se.group_node, tasks); |
1e3c88bd | 7311 | } |
5d6523eb | 7312 | |
1e3c88bd | 7313 | /* |
163122b7 KT |
7314 | * Right now, this is one of only two places we collect this stat |
7315 | * so we can safely collect detach_one_task() stats here rather | |
7316 | * than inside detach_one_task(). | |
1e3c88bd | 7317 | */ |
ae92882e | 7318 | schedstat_add(env->sd->lb_gained[env->idle], detached); |
1e3c88bd | 7319 | |
163122b7 KT |
7320 | return detached; |
7321 | } | |
7322 | ||
7323 | /* | |
7324 | * attach_task() -- attach the task detached by detach_task() to its new rq. | |
7325 | */ | |
7326 | static void attach_task(struct rq *rq, struct task_struct *p) | |
7327 | { | |
7328 | lockdep_assert_held(&rq->lock); | |
7329 | ||
7330 | BUG_ON(task_rq(p) != rq); | |
5704ac0a | 7331 | activate_task(rq, p, ENQUEUE_NOCLOCK); |
3ea94de1 | 7332 | p->on_rq = TASK_ON_RQ_QUEUED; |
163122b7 KT |
7333 | check_preempt_curr(rq, p, 0); |
7334 | } | |
7335 | ||
7336 | /* | |
7337 | * attach_one_task() -- attaches the task returned from detach_one_task() to | |
7338 | * its new rq. | |
7339 | */ | |
7340 | static void attach_one_task(struct rq *rq, struct task_struct *p) | |
7341 | { | |
8a8c69c3 PZ |
7342 | struct rq_flags rf; |
7343 | ||
7344 | rq_lock(rq, &rf); | |
5704ac0a | 7345 | update_rq_clock(rq); |
163122b7 | 7346 | attach_task(rq, p); |
8a8c69c3 | 7347 | rq_unlock(rq, &rf); |
163122b7 KT |
7348 | } |
7349 | ||
7350 | /* | |
7351 | * attach_tasks() -- attaches all tasks detached by detach_tasks() to their | |
7352 | * new rq. | |
7353 | */ | |
7354 | static void attach_tasks(struct lb_env *env) | |
7355 | { | |
7356 | struct list_head *tasks = &env->tasks; | |
7357 | struct task_struct *p; | |
8a8c69c3 | 7358 | struct rq_flags rf; |
163122b7 | 7359 | |
8a8c69c3 | 7360 | rq_lock(env->dst_rq, &rf); |
5704ac0a | 7361 | update_rq_clock(env->dst_rq); |
163122b7 KT |
7362 | |
7363 | while (!list_empty(tasks)) { | |
7364 | p = list_first_entry(tasks, struct task_struct, se.group_node); | |
7365 | list_del_init(&p->se.group_node); | |
1e3c88bd | 7366 | |
163122b7 KT |
7367 | attach_task(env->dst_rq, p); |
7368 | } | |
7369 | ||
8a8c69c3 | 7370 | rq_unlock(env->dst_rq, &rf); |
1e3c88bd PZ |
7371 | } |
7372 | ||
230059de | 7373 | #ifdef CONFIG_FAIR_GROUP_SCHED |
a9e7f654 | 7374 | |
48a16753 | 7375 | static void update_blocked_averages(int cpu) |
9e3081ca | 7376 | { |
9e3081ca | 7377 | struct rq *rq = cpu_rq(cpu); |
cf740dd8 | 7378 | struct cfs_rq *cfs_rq; |
8a8c69c3 | 7379 | struct rq_flags rf; |
9e3081ca | 7380 | |
8a8c69c3 | 7381 | rq_lock_irqsave(rq, &rf); |
48a16753 | 7382 | update_rq_clock(rq); |
9d89c257 | 7383 | |
9763b67f PZ |
7384 | /* |
7385 | * Iterates the task_group tree in a bottom up fashion, see | |
7386 | * list_add_leaf_cfs_rq() for details. | |
7387 | */ | |
cf740dd8 | 7388 | for_each_leaf_cfs_rq(rq, cfs_rq) { |
bc427898 VG |
7389 | struct sched_entity *se; |
7390 | ||
9d89c257 YD |
7391 | /* throttled entities do not contribute to load */ |
7392 | if (throttled_hierarchy(cfs_rq)) | |
7393 | continue; | |
48a16753 | 7394 | |
3a123bbb | 7395 | if (update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq)) |
9d89c257 | 7396 | update_tg_load_avg(cfs_rq, 0); |
4e516076 | 7397 | |
bc427898 VG |
7398 | /* Propagate pending load changes to the parent, if any: */ |
7399 | se = cfs_rq->tg->se[cpu]; | |
7400 | if (se && !skip_blocked_update(se)) | |
88c0616e | 7401 | update_load_avg(cfs_rq_of(se), se, 0); |
9d89c257 | 7402 | } |
8a8c69c3 | 7403 | rq_unlock_irqrestore(rq, &rf); |
9e3081ca PZ |
7404 | } |
7405 | ||
9763b67f | 7406 | /* |
68520796 | 7407 | * Compute the hierarchical load factor for cfs_rq and all its ascendants. |
9763b67f PZ |
7408 | * This needs to be done in a top-down fashion because the load of a child |
7409 | * group is a fraction of its parents load. | |
7410 | */ | |
68520796 | 7411 | static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq) |
9763b67f | 7412 | { |
68520796 VD |
7413 | struct rq *rq = rq_of(cfs_rq); |
7414 | struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)]; | |
a35b6466 | 7415 | unsigned long now = jiffies; |
68520796 | 7416 | unsigned long load; |
a35b6466 | 7417 | |
68520796 | 7418 | if (cfs_rq->last_h_load_update == now) |
a35b6466 PZ |
7419 | return; |
7420 | ||
cbeb7c02 | 7421 | WRITE_ONCE(cfs_rq->h_load_next, NULL); |
68520796 VD |
7422 | for_each_sched_entity(se) { |
7423 | cfs_rq = cfs_rq_of(se); | |
cbeb7c02 | 7424 | WRITE_ONCE(cfs_rq->h_load_next, se); |
68520796 VD |
7425 | if (cfs_rq->last_h_load_update == now) |
7426 | break; | |
7427 | } | |
a35b6466 | 7428 | |
68520796 | 7429 | if (!se) { |
7ea241af | 7430 | cfs_rq->h_load = cfs_rq_load_avg(cfs_rq); |
68520796 VD |
7431 | cfs_rq->last_h_load_update = now; |
7432 | } | |
7433 | ||
cbeb7c02 | 7434 | while ((se = READ_ONCE(cfs_rq->h_load_next)) != NULL) { |
68520796 | 7435 | load = cfs_rq->h_load; |
7ea241af YD |
7436 | load = div64_ul(load * se->avg.load_avg, |
7437 | cfs_rq_load_avg(cfs_rq) + 1); | |
68520796 VD |
7438 | cfs_rq = group_cfs_rq(se); |
7439 | cfs_rq->h_load = load; | |
7440 | cfs_rq->last_h_load_update = now; | |
7441 | } | |
9763b67f PZ |
7442 | } |
7443 | ||
367456c7 | 7444 | static unsigned long task_h_load(struct task_struct *p) |
230059de | 7445 | { |
367456c7 | 7446 | struct cfs_rq *cfs_rq = task_cfs_rq(p); |
230059de | 7447 | |
68520796 | 7448 | update_cfs_rq_h_load(cfs_rq); |
9d89c257 | 7449 | return div64_ul(p->se.avg.load_avg * cfs_rq->h_load, |
7ea241af | 7450 | cfs_rq_load_avg(cfs_rq) + 1); |
230059de PZ |
7451 | } |
7452 | #else | |
48a16753 | 7453 | static inline void update_blocked_averages(int cpu) |
9e3081ca | 7454 | { |
6c1d47c0 VG |
7455 | struct rq *rq = cpu_rq(cpu); |
7456 | struct cfs_rq *cfs_rq = &rq->cfs; | |
8a8c69c3 | 7457 | struct rq_flags rf; |
6c1d47c0 | 7458 | |
8a8c69c3 | 7459 | rq_lock_irqsave(rq, &rf); |
6c1d47c0 | 7460 | update_rq_clock(rq); |
3a123bbb | 7461 | update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq); |
8a8c69c3 | 7462 | rq_unlock_irqrestore(rq, &rf); |
9e3081ca PZ |
7463 | } |
7464 | ||
367456c7 | 7465 | static unsigned long task_h_load(struct task_struct *p) |
1e3c88bd | 7466 | { |
9d89c257 | 7467 | return p->se.avg.load_avg; |
1e3c88bd | 7468 | } |
230059de | 7469 | #endif |
1e3c88bd | 7470 | |
1e3c88bd | 7471 | /********** Helpers for find_busiest_group ************************/ |
caeb178c RR |
7472 | |
7473 | enum group_type { | |
7474 | group_other = 0, | |
7475 | group_imbalanced, | |
7476 | group_overloaded, | |
7477 | }; | |
7478 | ||
1e3c88bd PZ |
7479 | /* |
7480 | * sg_lb_stats - stats of a sched_group required for load_balancing | |
7481 | */ | |
7482 | struct sg_lb_stats { | |
7483 | unsigned long avg_load; /*Avg load across the CPUs of the group */ | |
7484 | unsigned long group_load; /* Total load over the CPUs of the group */ | |
1e3c88bd | 7485 | unsigned long sum_weighted_load; /* Weighted load of group's tasks */ |
56cf515b | 7486 | unsigned long load_per_task; |
63b2ca30 | 7487 | unsigned long group_capacity; |
9e91d61d | 7488 | unsigned long group_util; /* Total utilization of the group */ |
147c5fc2 | 7489 | unsigned int sum_nr_running; /* Nr tasks running in the group */ |
147c5fc2 PZ |
7490 | unsigned int idle_cpus; |
7491 | unsigned int group_weight; | |
caeb178c | 7492 | enum group_type group_type; |
ea67821b | 7493 | int group_no_capacity; |
0ec8aa00 PZ |
7494 | #ifdef CONFIG_NUMA_BALANCING |
7495 | unsigned int nr_numa_running; | |
7496 | unsigned int nr_preferred_running; | |
7497 | #endif | |
1e3c88bd PZ |
7498 | }; |
7499 | ||
56cf515b JK |
7500 | /* |
7501 | * sd_lb_stats - Structure to store the statistics of a sched_domain | |
7502 | * during load balancing. | |
7503 | */ | |
7504 | struct sd_lb_stats { | |
7505 | struct sched_group *busiest; /* Busiest group in this sd */ | |
7506 | struct sched_group *local; /* Local group in this sd */ | |
90001d67 | 7507 | unsigned long total_running; |
56cf515b | 7508 | unsigned long total_load; /* Total load of all groups in sd */ |
63b2ca30 | 7509 | unsigned long total_capacity; /* Total capacity of all groups in sd */ |
56cf515b JK |
7510 | unsigned long avg_load; /* Average load across all groups in sd */ |
7511 | ||
56cf515b | 7512 | struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */ |
147c5fc2 | 7513 | struct sg_lb_stats local_stat; /* Statistics of the local group */ |
56cf515b JK |
7514 | }; |
7515 | ||
147c5fc2 PZ |
7516 | static inline void init_sd_lb_stats(struct sd_lb_stats *sds) |
7517 | { | |
7518 | /* | |
7519 | * Skimp on the clearing to avoid duplicate work. We can avoid clearing | |
7520 | * local_stat because update_sg_lb_stats() does a full clear/assignment. | |
7521 | * We must however clear busiest_stat::avg_load because | |
7522 | * update_sd_pick_busiest() reads this before assignment. | |
7523 | */ | |
7524 | *sds = (struct sd_lb_stats){ | |
7525 | .busiest = NULL, | |
7526 | .local = NULL, | |
90001d67 | 7527 | .total_running = 0UL, |
147c5fc2 | 7528 | .total_load = 0UL, |
63b2ca30 | 7529 | .total_capacity = 0UL, |
147c5fc2 PZ |
7530 | .busiest_stat = { |
7531 | .avg_load = 0UL, | |
caeb178c RR |
7532 | .sum_nr_running = 0, |
7533 | .group_type = group_other, | |
147c5fc2 PZ |
7534 | }, |
7535 | }; | |
7536 | } | |
7537 | ||
1e3c88bd PZ |
7538 | /** |
7539 | * get_sd_load_idx - Obtain the load index for a given sched domain. | |
7540 | * @sd: The sched_domain whose load_idx is to be obtained. | |
ed1b7732 | 7541 | * @idle: The idle status of the CPU for whose sd load_idx is obtained. |
e69f6186 YB |
7542 | * |
7543 | * Return: The load index. | |
1e3c88bd PZ |
7544 | */ |
7545 | static inline int get_sd_load_idx(struct sched_domain *sd, | |
7546 | enum cpu_idle_type idle) | |
7547 | { | |
7548 | int load_idx; | |
7549 | ||
7550 | switch (idle) { | |
7551 | case CPU_NOT_IDLE: | |
7552 | load_idx = sd->busy_idx; | |
7553 | break; | |
7554 | ||
7555 | case CPU_NEWLY_IDLE: | |
7556 | load_idx = sd->newidle_idx; | |
7557 | break; | |
7558 | default: | |
7559 | load_idx = sd->idle_idx; | |
7560 | break; | |
7561 | } | |
7562 | ||
7563 | return load_idx; | |
7564 | } | |
7565 | ||
ced549fa | 7566 | static unsigned long scale_rt_capacity(int cpu) |
1e3c88bd PZ |
7567 | { |
7568 | struct rq *rq = cpu_rq(cpu); | |
b5b4860d | 7569 | u64 total, used, age_stamp, avg; |
cadefd3d | 7570 | s64 delta; |
1e3c88bd | 7571 | |
b654f7de PZ |
7572 | /* |
7573 | * Since we're reading these variables without serialization make sure | |
7574 | * we read them once before doing sanity checks on them. | |
7575 | */ | |
316c1608 JL |
7576 | age_stamp = READ_ONCE(rq->age_stamp); |
7577 | avg = READ_ONCE(rq->rt_avg); | |
cebde6d6 | 7578 | delta = __rq_clock_broken(rq) - age_stamp; |
b654f7de | 7579 | |
cadefd3d PZ |
7580 | if (unlikely(delta < 0)) |
7581 | delta = 0; | |
7582 | ||
7583 | total = sched_avg_period() + delta; | |
aa483808 | 7584 | |
b5b4860d | 7585 | used = div_u64(avg, total); |
1e3c88bd | 7586 | |
b5b4860d VG |
7587 | if (likely(used < SCHED_CAPACITY_SCALE)) |
7588 | return SCHED_CAPACITY_SCALE - used; | |
1e3c88bd | 7589 | |
b5b4860d | 7590 | return 1; |
1e3c88bd PZ |
7591 | } |
7592 | ||
ced549fa | 7593 | static void update_cpu_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd | 7594 | { |
8cd5601c | 7595 | unsigned long capacity = arch_scale_cpu_capacity(sd, cpu); |
1e3c88bd PZ |
7596 | struct sched_group *sdg = sd->groups; |
7597 | ||
ca6d75e6 | 7598 | cpu_rq(cpu)->cpu_capacity_orig = capacity; |
9d5efe05 | 7599 | |
ced549fa | 7600 | capacity *= scale_rt_capacity(cpu); |
ca8ce3d0 | 7601 | capacity >>= SCHED_CAPACITY_SHIFT; |
1e3c88bd | 7602 | |
ced549fa NP |
7603 | if (!capacity) |
7604 | capacity = 1; | |
1e3c88bd | 7605 | |
ced549fa NP |
7606 | cpu_rq(cpu)->cpu_capacity = capacity; |
7607 | sdg->sgc->capacity = capacity; | |
bf475ce0 | 7608 | sdg->sgc->min_capacity = capacity; |
1e3c88bd PZ |
7609 | } |
7610 | ||
63b2ca30 | 7611 | void update_group_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd PZ |
7612 | { |
7613 | struct sched_domain *child = sd->child; | |
7614 | struct sched_group *group, *sdg = sd->groups; | |
bf475ce0 | 7615 | unsigned long capacity, min_capacity; |
4ec4412e VG |
7616 | unsigned long interval; |
7617 | ||
7618 | interval = msecs_to_jiffies(sd->balance_interval); | |
7619 | interval = clamp(interval, 1UL, max_load_balance_interval); | |
63b2ca30 | 7620 | sdg->sgc->next_update = jiffies + interval; |
1e3c88bd PZ |
7621 | |
7622 | if (!child) { | |
ced549fa | 7623 | update_cpu_capacity(sd, cpu); |
1e3c88bd PZ |
7624 | return; |
7625 | } | |
7626 | ||
dc7ff76e | 7627 | capacity = 0; |
bf475ce0 | 7628 | min_capacity = ULONG_MAX; |
1e3c88bd | 7629 | |
74a5ce20 PZ |
7630 | if (child->flags & SD_OVERLAP) { |
7631 | /* | |
7632 | * SD_OVERLAP domains cannot assume that child groups | |
7633 | * span the current group. | |
7634 | */ | |
7635 | ||
ae4df9d6 | 7636 | for_each_cpu(cpu, sched_group_span(sdg)) { |
63b2ca30 | 7637 | struct sched_group_capacity *sgc; |
9abf24d4 | 7638 | struct rq *rq = cpu_rq(cpu); |
863bffc8 | 7639 | |
9abf24d4 | 7640 | /* |
63b2ca30 | 7641 | * build_sched_domains() -> init_sched_groups_capacity() |
9abf24d4 SD |
7642 | * gets here before we've attached the domains to the |
7643 | * runqueues. | |
7644 | * | |
ced549fa NP |
7645 | * Use capacity_of(), which is set irrespective of domains |
7646 | * in update_cpu_capacity(). | |
9abf24d4 | 7647 | * |
dc7ff76e | 7648 | * This avoids capacity from being 0 and |
9abf24d4 | 7649 | * causing divide-by-zero issues on boot. |
9abf24d4 SD |
7650 | */ |
7651 | if (unlikely(!rq->sd)) { | |
ced549fa | 7652 | capacity += capacity_of(cpu); |
bf475ce0 MR |
7653 | } else { |
7654 | sgc = rq->sd->groups->sgc; | |
7655 | capacity += sgc->capacity; | |
9abf24d4 | 7656 | } |
863bffc8 | 7657 | |
bf475ce0 | 7658 | min_capacity = min(capacity, min_capacity); |
863bffc8 | 7659 | } |
74a5ce20 PZ |
7660 | } else { |
7661 | /* | |
7662 | * !SD_OVERLAP domains can assume that child groups | |
7663 | * span the current group. | |
97a7142f | 7664 | */ |
74a5ce20 PZ |
7665 | |
7666 | group = child->groups; | |
7667 | do { | |
bf475ce0 MR |
7668 | struct sched_group_capacity *sgc = group->sgc; |
7669 | ||
7670 | capacity += sgc->capacity; | |
7671 | min_capacity = min(sgc->min_capacity, min_capacity); | |
74a5ce20 PZ |
7672 | group = group->next; |
7673 | } while (group != child->groups); | |
7674 | } | |
1e3c88bd | 7675 | |
63b2ca30 | 7676 | sdg->sgc->capacity = capacity; |
bf475ce0 | 7677 | sdg->sgc->min_capacity = min_capacity; |
1e3c88bd PZ |
7678 | } |
7679 | ||
9d5efe05 | 7680 | /* |
ea67821b VG |
7681 | * Check whether the capacity of the rq has been noticeably reduced by side |
7682 | * activity. The imbalance_pct is used for the threshold. | |
7683 | * Return true is the capacity is reduced | |
9d5efe05 SV |
7684 | */ |
7685 | static inline int | |
ea67821b | 7686 | check_cpu_capacity(struct rq *rq, struct sched_domain *sd) |
9d5efe05 | 7687 | { |
ea67821b VG |
7688 | return ((rq->cpu_capacity * sd->imbalance_pct) < |
7689 | (rq->cpu_capacity_orig * 100)); | |
9d5efe05 SV |
7690 | } |
7691 | ||
30ce5dab PZ |
7692 | /* |
7693 | * Group imbalance indicates (and tries to solve) the problem where balancing | |
0c98d344 | 7694 | * groups is inadequate due to ->cpus_allowed constraints. |
30ce5dab PZ |
7695 | * |
7696 | * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a | |
7697 | * cpumask covering 1 cpu of the first group and 3 cpus of the second group. | |
7698 | * Something like: | |
7699 | * | |
2b4d5b25 IM |
7700 | * { 0 1 2 3 } { 4 5 6 7 } |
7701 | * * * * * | |
30ce5dab PZ |
7702 | * |
7703 | * If we were to balance group-wise we'd place two tasks in the first group and | |
7704 | * two tasks in the second group. Clearly this is undesired as it will overload | |
7705 | * cpu 3 and leave one of the cpus in the second group unused. | |
7706 | * | |
7707 | * The current solution to this issue is detecting the skew in the first group | |
6263322c PZ |
7708 | * by noticing the lower domain failed to reach balance and had difficulty |
7709 | * moving tasks due to affinity constraints. | |
30ce5dab PZ |
7710 | * |
7711 | * When this is so detected; this group becomes a candidate for busiest; see | |
ed1b7732 | 7712 | * update_sd_pick_busiest(). And calculate_imbalance() and |
6263322c | 7713 | * find_busiest_group() avoid some of the usual balance conditions to allow it |
30ce5dab PZ |
7714 | * to create an effective group imbalance. |
7715 | * | |
7716 | * This is a somewhat tricky proposition since the next run might not find the | |
7717 | * group imbalance and decide the groups need to be balanced again. A most | |
7718 | * subtle and fragile situation. | |
7719 | */ | |
7720 | ||
6263322c | 7721 | static inline int sg_imbalanced(struct sched_group *group) |
30ce5dab | 7722 | { |
63b2ca30 | 7723 | return group->sgc->imbalance; |
30ce5dab PZ |
7724 | } |
7725 | ||
b37d9316 | 7726 | /* |
ea67821b VG |
7727 | * group_has_capacity returns true if the group has spare capacity that could |
7728 | * be used by some tasks. | |
7729 | * We consider that a group has spare capacity if the * number of task is | |
9e91d61d DE |
7730 | * smaller than the number of CPUs or if the utilization is lower than the |
7731 | * available capacity for CFS tasks. | |
ea67821b VG |
7732 | * For the latter, we use a threshold to stabilize the state, to take into |
7733 | * account the variance of the tasks' load and to return true if the available | |
7734 | * capacity in meaningful for the load balancer. | |
7735 | * As an example, an available capacity of 1% can appear but it doesn't make | |
7736 | * any benefit for the load balance. | |
b37d9316 | 7737 | */ |
ea67821b VG |
7738 | static inline bool |
7739 | group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs) | |
b37d9316 | 7740 | { |
ea67821b VG |
7741 | if (sgs->sum_nr_running < sgs->group_weight) |
7742 | return true; | |
c61037e9 | 7743 | |
ea67821b | 7744 | if ((sgs->group_capacity * 100) > |
9e91d61d | 7745 | (sgs->group_util * env->sd->imbalance_pct)) |
ea67821b | 7746 | return true; |
b37d9316 | 7747 | |
ea67821b VG |
7748 | return false; |
7749 | } | |
7750 | ||
7751 | /* | |
7752 | * group_is_overloaded returns true if the group has more tasks than it can | |
7753 | * handle. | |
7754 | * group_is_overloaded is not equals to !group_has_capacity because a group | |
7755 | * with the exact right number of tasks, has no more spare capacity but is not | |
7756 | * overloaded so both group_has_capacity and group_is_overloaded return | |
7757 | * false. | |
7758 | */ | |
7759 | static inline bool | |
7760 | group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs) | |
7761 | { | |
7762 | if (sgs->sum_nr_running <= sgs->group_weight) | |
7763 | return false; | |
b37d9316 | 7764 | |
ea67821b | 7765 | if ((sgs->group_capacity * 100) < |
9e91d61d | 7766 | (sgs->group_util * env->sd->imbalance_pct)) |
ea67821b | 7767 | return true; |
b37d9316 | 7768 | |
ea67821b | 7769 | return false; |
b37d9316 PZ |
7770 | } |
7771 | ||
9e0994c0 MR |
7772 | /* |
7773 | * group_smaller_cpu_capacity: Returns true if sched_group sg has smaller | |
7774 | * per-CPU capacity than sched_group ref. | |
7775 | */ | |
7776 | static inline bool | |
7777 | group_smaller_cpu_capacity(struct sched_group *sg, struct sched_group *ref) | |
7778 | { | |
7779 | return sg->sgc->min_capacity * capacity_margin < | |
7780 | ref->sgc->min_capacity * 1024; | |
7781 | } | |
7782 | ||
79a89f92 LY |
7783 | static inline enum |
7784 | group_type group_classify(struct sched_group *group, | |
7785 | struct sg_lb_stats *sgs) | |
caeb178c | 7786 | { |
ea67821b | 7787 | if (sgs->group_no_capacity) |
caeb178c RR |
7788 | return group_overloaded; |
7789 | ||
7790 | if (sg_imbalanced(group)) | |
7791 | return group_imbalanced; | |
7792 | ||
7793 | return group_other; | |
7794 | } | |
7795 | ||
1e3c88bd PZ |
7796 | /** |
7797 | * update_sg_lb_stats - Update sched_group's statistics for load balancing. | |
cd96891d | 7798 | * @env: The load balancing environment. |
1e3c88bd | 7799 | * @group: sched_group whose statistics are to be updated. |
1e3c88bd | 7800 | * @load_idx: Load index of sched_domain of this_cpu for load calc. |
1e3c88bd | 7801 | * @local_group: Does group contain this_cpu. |
1e3c88bd | 7802 | * @sgs: variable to hold the statistics for this group. |
cd3bd4e6 | 7803 | * @overload: Indicate more than one runnable task for any CPU. |
1e3c88bd | 7804 | */ |
bd939f45 PZ |
7805 | static inline void update_sg_lb_stats(struct lb_env *env, |
7806 | struct sched_group *group, int load_idx, | |
4486edd1 TC |
7807 | int local_group, struct sg_lb_stats *sgs, |
7808 | bool *overload) | |
1e3c88bd | 7809 | { |
30ce5dab | 7810 | unsigned long load; |
a426f99c | 7811 | int i, nr_running; |
1e3c88bd | 7812 | |
b72ff13c PZ |
7813 | memset(sgs, 0, sizeof(*sgs)); |
7814 | ||
ae4df9d6 | 7815 | for_each_cpu_and(i, sched_group_span(group), env->cpus) { |
1e3c88bd PZ |
7816 | struct rq *rq = cpu_rq(i); |
7817 | ||
1e3c88bd | 7818 | /* Bias balancing toward cpus of our domain */ |
6263322c | 7819 | if (local_group) |
04f733b4 | 7820 | load = target_load(i, load_idx); |
6263322c | 7821 | else |
1e3c88bd | 7822 | load = source_load(i, load_idx); |
1e3c88bd PZ |
7823 | |
7824 | sgs->group_load += load; | |
9e91d61d | 7825 | sgs->group_util += cpu_util(i); |
65fdac08 | 7826 | sgs->sum_nr_running += rq->cfs.h_nr_running; |
4486edd1 | 7827 | |
a426f99c WL |
7828 | nr_running = rq->nr_running; |
7829 | if (nr_running > 1) | |
4486edd1 TC |
7830 | *overload = true; |
7831 | ||
0ec8aa00 PZ |
7832 | #ifdef CONFIG_NUMA_BALANCING |
7833 | sgs->nr_numa_running += rq->nr_numa_running; | |
7834 | sgs->nr_preferred_running += rq->nr_preferred_running; | |
7835 | #endif | |
c7132dd6 | 7836 | sgs->sum_weighted_load += weighted_cpuload(rq); |
a426f99c WL |
7837 | /* |
7838 | * No need to call idle_cpu() if nr_running is not 0 | |
7839 | */ | |
7840 | if (!nr_running && idle_cpu(i)) | |
aae6d3dd | 7841 | sgs->idle_cpus++; |
1e3c88bd PZ |
7842 | } |
7843 | ||
63b2ca30 NP |
7844 | /* Adjust by relative CPU capacity of the group */ |
7845 | sgs->group_capacity = group->sgc->capacity; | |
ca8ce3d0 | 7846 | sgs->avg_load = (sgs->group_load*SCHED_CAPACITY_SCALE) / sgs->group_capacity; |
1e3c88bd | 7847 | |
dd5feea1 | 7848 | if (sgs->sum_nr_running) |
38d0f770 | 7849 | sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; |
1e3c88bd | 7850 | |
aae6d3dd | 7851 | sgs->group_weight = group->group_weight; |
b37d9316 | 7852 | |
ea67821b | 7853 | sgs->group_no_capacity = group_is_overloaded(env, sgs); |
79a89f92 | 7854 | sgs->group_type = group_classify(group, sgs); |
1e3c88bd PZ |
7855 | } |
7856 | ||
532cb4c4 MN |
7857 | /** |
7858 | * update_sd_pick_busiest - return 1 on busiest group | |
cd96891d | 7859 | * @env: The load balancing environment. |
532cb4c4 MN |
7860 | * @sds: sched_domain statistics |
7861 | * @sg: sched_group candidate to be checked for being the busiest | |
b6b12294 | 7862 | * @sgs: sched_group statistics |
532cb4c4 MN |
7863 | * |
7864 | * Determine if @sg is a busier group than the previously selected | |
7865 | * busiest group. | |
e69f6186 YB |
7866 | * |
7867 | * Return: %true if @sg is a busier group than the previously selected | |
7868 | * busiest group. %false otherwise. | |
532cb4c4 | 7869 | */ |
bd939f45 | 7870 | static bool update_sd_pick_busiest(struct lb_env *env, |
532cb4c4 MN |
7871 | struct sd_lb_stats *sds, |
7872 | struct sched_group *sg, | |
bd939f45 | 7873 | struct sg_lb_stats *sgs) |
532cb4c4 | 7874 | { |
caeb178c | 7875 | struct sg_lb_stats *busiest = &sds->busiest_stat; |
532cb4c4 | 7876 | |
caeb178c | 7877 | if (sgs->group_type > busiest->group_type) |
532cb4c4 MN |
7878 | return true; |
7879 | ||
caeb178c RR |
7880 | if (sgs->group_type < busiest->group_type) |
7881 | return false; | |
7882 | ||
7883 | if (sgs->avg_load <= busiest->avg_load) | |
7884 | return false; | |
7885 | ||
9e0994c0 MR |
7886 | if (!(env->sd->flags & SD_ASYM_CPUCAPACITY)) |
7887 | goto asym_packing; | |
7888 | ||
7889 | /* | |
7890 | * Candidate sg has no more than one task per CPU and | |
7891 | * has higher per-CPU capacity. Migrating tasks to less | |
7892 | * capable CPUs may harm throughput. Maximize throughput, | |
7893 | * power/energy consequences are not considered. | |
7894 | */ | |
7895 | if (sgs->sum_nr_running <= sgs->group_weight && | |
7896 | group_smaller_cpu_capacity(sds->local, sg)) | |
7897 | return false; | |
7898 | ||
7899 | asym_packing: | |
caeb178c RR |
7900 | /* This is the busiest node in its class. */ |
7901 | if (!(env->sd->flags & SD_ASYM_PACKING)) | |
532cb4c4 MN |
7902 | return true; |
7903 | ||
1f621e02 SD |
7904 | /* No ASYM_PACKING if target cpu is already busy */ |
7905 | if (env->idle == CPU_NOT_IDLE) | |
7906 | return true; | |
532cb4c4 | 7907 | /* |
afe06efd TC |
7908 | * ASYM_PACKING needs to move all the work to the highest |
7909 | * prority CPUs in the group, therefore mark all groups | |
7910 | * of lower priority than ourself as busy. | |
532cb4c4 | 7911 | */ |
afe06efd TC |
7912 | if (sgs->sum_nr_running && |
7913 | sched_asym_prefer(env->dst_cpu, sg->asym_prefer_cpu)) { | |
532cb4c4 MN |
7914 | if (!sds->busiest) |
7915 | return true; | |
7916 | ||
afe06efd TC |
7917 | /* Prefer to move from lowest priority cpu's work */ |
7918 | if (sched_asym_prefer(sds->busiest->asym_prefer_cpu, | |
7919 | sg->asym_prefer_cpu)) | |
532cb4c4 MN |
7920 | return true; |
7921 | } | |
7922 | ||
7923 | return false; | |
7924 | } | |
7925 | ||
0ec8aa00 PZ |
7926 | #ifdef CONFIG_NUMA_BALANCING |
7927 | static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) | |
7928 | { | |
7929 | if (sgs->sum_nr_running > sgs->nr_numa_running) | |
7930 | return regular; | |
7931 | if (sgs->sum_nr_running > sgs->nr_preferred_running) | |
7932 | return remote; | |
7933 | return all; | |
7934 | } | |
7935 | ||
7936 | static inline enum fbq_type fbq_classify_rq(struct rq *rq) | |
7937 | { | |
7938 | if (rq->nr_running > rq->nr_numa_running) | |
7939 | return regular; | |
7940 | if (rq->nr_running > rq->nr_preferred_running) | |
7941 | return remote; | |
7942 | return all; | |
7943 | } | |
7944 | #else | |
7945 | static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) | |
7946 | { | |
7947 | return all; | |
7948 | } | |
7949 | ||
7950 | static inline enum fbq_type fbq_classify_rq(struct rq *rq) | |
7951 | { | |
7952 | return regular; | |
7953 | } | |
7954 | #endif /* CONFIG_NUMA_BALANCING */ | |
7955 | ||
1e3c88bd | 7956 | /** |
461819ac | 7957 | * update_sd_lb_stats - Update sched_domain's statistics for load balancing. |
cd96891d | 7958 | * @env: The load balancing environment. |
1e3c88bd PZ |
7959 | * @sds: variable to hold the statistics for this sched_domain. |
7960 | */ | |
0ec8aa00 | 7961 | static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds) |
1e3c88bd | 7962 | { |
bd939f45 PZ |
7963 | struct sched_domain *child = env->sd->child; |
7964 | struct sched_group *sg = env->sd->groups; | |
05b40e05 | 7965 | struct sg_lb_stats *local = &sds->local_stat; |
56cf515b | 7966 | struct sg_lb_stats tmp_sgs; |
1e3c88bd | 7967 | int load_idx, prefer_sibling = 0; |
4486edd1 | 7968 | bool overload = false; |
1e3c88bd PZ |
7969 | |
7970 | if (child && child->flags & SD_PREFER_SIBLING) | |
7971 | prefer_sibling = 1; | |
7972 | ||
bd939f45 | 7973 | load_idx = get_sd_load_idx(env->sd, env->idle); |
1e3c88bd PZ |
7974 | |
7975 | do { | |
56cf515b | 7976 | struct sg_lb_stats *sgs = &tmp_sgs; |
1e3c88bd PZ |
7977 | int local_group; |
7978 | ||
ae4df9d6 | 7979 | local_group = cpumask_test_cpu(env->dst_cpu, sched_group_span(sg)); |
56cf515b JK |
7980 | if (local_group) { |
7981 | sds->local = sg; | |
05b40e05 | 7982 | sgs = local; |
b72ff13c PZ |
7983 | |
7984 | if (env->idle != CPU_NEWLY_IDLE || | |
63b2ca30 NP |
7985 | time_after_eq(jiffies, sg->sgc->next_update)) |
7986 | update_group_capacity(env->sd, env->dst_cpu); | |
56cf515b | 7987 | } |
1e3c88bd | 7988 | |
4486edd1 TC |
7989 | update_sg_lb_stats(env, sg, load_idx, local_group, sgs, |
7990 | &overload); | |
1e3c88bd | 7991 | |
b72ff13c PZ |
7992 | if (local_group) |
7993 | goto next_group; | |
7994 | ||
1e3c88bd PZ |
7995 | /* |
7996 | * In case the child domain prefers tasks go to siblings | |
ea67821b | 7997 | * first, lower the sg capacity so that we'll try |
75dd321d NR |
7998 | * and move all the excess tasks away. We lower the capacity |
7999 | * of a group only if the local group has the capacity to fit | |
ea67821b VG |
8000 | * these excess tasks. The extra check prevents the case where |
8001 | * you always pull from the heaviest group when it is already | |
8002 | * under-utilized (possible with a large weight task outweighs | |
8003 | * the tasks on the system). | |
1e3c88bd | 8004 | */ |
b72ff13c | 8005 | if (prefer_sibling && sds->local && |
05b40e05 SD |
8006 | group_has_capacity(env, local) && |
8007 | (sgs->sum_nr_running > local->sum_nr_running + 1)) { | |
ea67821b | 8008 | sgs->group_no_capacity = 1; |
79a89f92 | 8009 | sgs->group_type = group_classify(sg, sgs); |
cb0b9f24 | 8010 | } |
1e3c88bd | 8011 | |
b72ff13c | 8012 | if (update_sd_pick_busiest(env, sds, sg, sgs)) { |
532cb4c4 | 8013 | sds->busiest = sg; |
56cf515b | 8014 | sds->busiest_stat = *sgs; |
1e3c88bd PZ |
8015 | } |
8016 | ||
b72ff13c PZ |
8017 | next_group: |
8018 | /* Now, start updating sd_lb_stats */ | |
90001d67 | 8019 | sds->total_running += sgs->sum_nr_running; |
b72ff13c | 8020 | sds->total_load += sgs->group_load; |
63b2ca30 | 8021 | sds->total_capacity += sgs->group_capacity; |
b72ff13c | 8022 | |
532cb4c4 | 8023 | sg = sg->next; |
bd939f45 | 8024 | } while (sg != env->sd->groups); |
0ec8aa00 PZ |
8025 | |
8026 | if (env->sd->flags & SD_NUMA) | |
8027 | env->fbq_type = fbq_classify_group(&sds->busiest_stat); | |
4486edd1 TC |
8028 | |
8029 | if (!env->sd->parent) { | |
8030 | /* update overload indicator if we are at root domain */ | |
8031 | if (env->dst_rq->rd->overload != overload) | |
8032 | env->dst_rq->rd->overload = overload; | |
8033 | } | |
532cb4c4 MN |
8034 | } |
8035 | ||
532cb4c4 MN |
8036 | /** |
8037 | * check_asym_packing - Check to see if the group is packed into the | |
0ba42a59 | 8038 | * sched domain. |
532cb4c4 MN |
8039 | * |
8040 | * This is primarily intended to used at the sibling level. Some | |
8041 | * cores like POWER7 prefer to use lower numbered SMT threads. In the | |
8042 | * case of POWER7, it can move to lower SMT modes only when higher | |
8043 | * threads are idle. When in lower SMT modes, the threads will | |
8044 | * perform better since they share less core resources. Hence when we | |
8045 | * have idle threads, we want them to be the higher ones. | |
8046 | * | |
8047 | * This packing function is run on idle threads. It checks to see if | |
8048 | * the busiest CPU in this domain (core in the P7 case) has a higher | |
8049 | * CPU number than the packing function is being run on. Here we are | |
8050 | * assuming lower CPU number will be equivalent to lower a SMT thread | |
8051 | * number. | |
8052 | * | |
e69f6186 | 8053 | * Return: 1 when packing is required and a task should be moved to |
46123355 | 8054 | * this CPU. The amount of the imbalance is returned in env->imbalance. |
b6b12294 | 8055 | * |
cd96891d | 8056 | * @env: The load balancing environment. |
532cb4c4 | 8057 | * @sds: Statistics of the sched_domain which is to be packed |
532cb4c4 | 8058 | */ |
bd939f45 | 8059 | static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds) |
532cb4c4 MN |
8060 | { |
8061 | int busiest_cpu; | |
8062 | ||
bd939f45 | 8063 | if (!(env->sd->flags & SD_ASYM_PACKING)) |
532cb4c4 MN |
8064 | return 0; |
8065 | ||
1f621e02 SD |
8066 | if (env->idle == CPU_NOT_IDLE) |
8067 | return 0; | |
8068 | ||
532cb4c4 MN |
8069 | if (!sds->busiest) |
8070 | return 0; | |
8071 | ||
afe06efd TC |
8072 | busiest_cpu = sds->busiest->asym_prefer_cpu; |
8073 | if (sched_asym_prefer(busiest_cpu, env->dst_cpu)) | |
532cb4c4 MN |
8074 | return 0; |
8075 | ||
bd939f45 | 8076 | env->imbalance = DIV_ROUND_CLOSEST( |
63b2ca30 | 8077 | sds->busiest_stat.avg_load * sds->busiest_stat.group_capacity, |
ca8ce3d0 | 8078 | SCHED_CAPACITY_SCALE); |
bd939f45 | 8079 | |
532cb4c4 | 8080 | return 1; |
1e3c88bd PZ |
8081 | } |
8082 | ||
8083 | /** | |
8084 | * fix_small_imbalance - Calculate the minor imbalance that exists | |
8085 | * amongst the groups of a sched_domain, during | |
8086 | * load balancing. | |
cd96891d | 8087 | * @env: The load balancing environment. |
1e3c88bd | 8088 | * @sds: Statistics of the sched_domain whose imbalance is to be calculated. |
1e3c88bd | 8089 | */ |
bd939f45 PZ |
8090 | static inline |
8091 | void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds) | |
1e3c88bd | 8092 | { |
63b2ca30 | 8093 | unsigned long tmp, capa_now = 0, capa_move = 0; |
1e3c88bd | 8094 | unsigned int imbn = 2; |
dd5feea1 | 8095 | unsigned long scaled_busy_load_per_task; |
56cf515b | 8096 | struct sg_lb_stats *local, *busiest; |
1e3c88bd | 8097 | |
56cf515b JK |
8098 | local = &sds->local_stat; |
8099 | busiest = &sds->busiest_stat; | |
1e3c88bd | 8100 | |
56cf515b JK |
8101 | if (!local->sum_nr_running) |
8102 | local->load_per_task = cpu_avg_load_per_task(env->dst_cpu); | |
8103 | else if (busiest->load_per_task > local->load_per_task) | |
8104 | imbn = 1; | |
dd5feea1 | 8105 | |
56cf515b | 8106 | scaled_busy_load_per_task = |
ca8ce3d0 | 8107 | (busiest->load_per_task * SCHED_CAPACITY_SCALE) / |
63b2ca30 | 8108 | busiest->group_capacity; |
56cf515b | 8109 | |
3029ede3 VD |
8110 | if (busiest->avg_load + scaled_busy_load_per_task >= |
8111 | local->avg_load + (scaled_busy_load_per_task * imbn)) { | |
56cf515b | 8112 | env->imbalance = busiest->load_per_task; |
1e3c88bd PZ |
8113 | return; |
8114 | } | |
8115 | ||
8116 | /* | |
8117 | * OK, we don't have enough imbalance to justify moving tasks, | |
ced549fa | 8118 | * however we may be able to increase total CPU capacity used by |
1e3c88bd PZ |
8119 | * moving them. |
8120 | */ | |
8121 | ||
63b2ca30 | 8122 | capa_now += busiest->group_capacity * |
56cf515b | 8123 | min(busiest->load_per_task, busiest->avg_load); |
63b2ca30 | 8124 | capa_now += local->group_capacity * |
56cf515b | 8125 | min(local->load_per_task, local->avg_load); |
ca8ce3d0 | 8126 | capa_now /= SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
8127 | |
8128 | /* Amount of load we'd subtract */ | |
a2cd4260 | 8129 | if (busiest->avg_load > scaled_busy_load_per_task) { |
63b2ca30 | 8130 | capa_move += busiest->group_capacity * |
56cf515b | 8131 | min(busiest->load_per_task, |
a2cd4260 | 8132 | busiest->avg_load - scaled_busy_load_per_task); |
56cf515b | 8133 | } |
1e3c88bd PZ |
8134 | |
8135 | /* Amount of load we'd add */ | |
63b2ca30 | 8136 | if (busiest->avg_load * busiest->group_capacity < |
ca8ce3d0 | 8137 | busiest->load_per_task * SCHED_CAPACITY_SCALE) { |
63b2ca30 NP |
8138 | tmp = (busiest->avg_load * busiest->group_capacity) / |
8139 | local->group_capacity; | |
56cf515b | 8140 | } else { |
ca8ce3d0 | 8141 | tmp = (busiest->load_per_task * SCHED_CAPACITY_SCALE) / |
63b2ca30 | 8142 | local->group_capacity; |
56cf515b | 8143 | } |
63b2ca30 | 8144 | capa_move += local->group_capacity * |
3ae11c90 | 8145 | min(local->load_per_task, local->avg_load + tmp); |
ca8ce3d0 | 8146 | capa_move /= SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
8147 | |
8148 | /* Move if we gain throughput */ | |
63b2ca30 | 8149 | if (capa_move > capa_now) |
56cf515b | 8150 | env->imbalance = busiest->load_per_task; |
1e3c88bd PZ |
8151 | } |
8152 | ||
8153 | /** | |
8154 | * calculate_imbalance - Calculate the amount of imbalance present within the | |
8155 | * groups of a given sched_domain during load balance. | |
bd939f45 | 8156 | * @env: load balance environment |
1e3c88bd | 8157 | * @sds: statistics of the sched_domain whose imbalance is to be calculated. |
1e3c88bd | 8158 | */ |
bd939f45 | 8159 | static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds) |
1e3c88bd | 8160 | { |
dd5feea1 | 8161 | unsigned long max_pull, load_above_capacity = ~0UL; |
56cf515b JK |
8162 | struct sg_lb_stats *local, *busiest; |
8163 | ||
8164 | local = &sds->local_stat; | |
56cf515b | 8165 | busiest = &sds->busiest_stat; |
dd5feea1 | 8166 | |
caeb178c | 8167 | if (busiest->group_type == group_imbalanced) { |
30ce5dab PZ |
8168 | /* |
8169 | * In the group_imb case we cannot rely on group-wide averages | |
8170 | * to ensure cpu-load equilibrium, look at wider averages. XXX | |
8171 | */ | |
56cf515b JK |
8172 | busiest->load_per_task = |
8173 | min(busiest->load_per_task, sds->avg_load); | |
dd5feea1 SS |
8174 | } |
8175 | ||
1e3c88bd | 8176 | /* |
885e542c DE |
8177 | * Avg load of busiest sg can be less and avg load of local sg can |
8178 | * be greater than avg load across all sgs of sd because avg load | |
8179 | * factors in sg capacity and sgs with smaller group_type are | |
8180 | * skipped when updating the busiest sg: | |
1e3c88bd | 8181 | */ |
b1885550 VD |
8182 | if (busiest->avg_load <= sds->avg_load || |
8183 | local->avg_load >= sds->avg_load) { | |
bd939f45 PZ |
8184 | env->imbalance = 0; |
8185 | return fix_small_imbalance(env, sds); | |
1e3c88bd PZ |
8186 | } |
8187 | ||
9a5d9ba6 PZ |
8188 | /* |
8189 | * If there aren't any idle cpus, avoid creating some. | |
8190 | */ | |
8191 | if (busiest->group_type == group_overloaded && | |
8192 | local->group_type == group_overloaded) { | |
1be0eb2a | 8193 | load_above_capacity = busiest->sum_nr_running * SCHED_CAPACITY_SCALE; |
cfa10334 | 8194 | if (load_above_capacity > busiest->group_capacity) { |
ea67821b | 8195 | load_above_capacity -= busiest->group_capacity; |
26656215 | 8196 | load_above_capacity *= scale_load_down(NICE_0_LOAD); |
cfa10334 MR |
8197 | load_above_capacity /= busiest->group_capacity; |
8198 | } else | |
ea67821b | 8199 | load_above_capacity = ~0UL; |
dd5feea1 SS |
8200 | } |
8201 | ||
8202 | /* | |
8203 | * We're trying to get all the cpus to the average_load, so we don't | |
8204 | * want to push ourselves above the average load, nor do we wish to | |
8205 | * reduce the max loaded cpu below the average load. At the same time, | |
0a9b23ce DE |
8206 | * we also don't want to reduce the group load below the group |
8207 | * capacity. Thus we look for the minimum possible imbalance. | |
dd5feea1 | 8208 | */ |
30ce5dab | 8209 | max_pull = min(busiest->avg_load - sds->avg_load, load_above_capacity); |
1e3c88bd PZ |
8210 | |
8211 | /* How much load to actually move to equalise the imbalance */ | |
56cf515b | 8212 | env->imbalance = min( |
63b2ca30 NP |
8213 | max_pull * busiest->group_capacity, |
8214 | (sds->avg_load - local->avg_load) * local->group_capacity | |
ca8ce3d0 | 8215 | ) / SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
8216 | |
8217 | /* | |
8218 | * if *imbalance is less than the average load per runnable task | |
25985edc | 8219 | * there is no guarantee that any tasks will be moved so we'll have |
1e3c88bd PZ |
8220 | * a think about bumping its value to force at least one task to be |
8221 | * moved | |
8222 | */ | |
56cf515b | 8223 | if (env->imbalance < busiest->load_per_task) |
bd939f45 | 8224 | return fix_small_imbalance(env, sds); |
1e3c88bd | 8225 | } |
fab47622 | 8226 | |
1e3c88bd PZ |
8227 | /******* find_busiest_group() helpers end here *********************/ |
8228 | ||
8229 | /** | |
8230 | * find_busiest_group - Returns the busiest group within the sched_domain | |
0a9b23ce | 8231 | * if there is an imbalance. |
1e3c88bd PZ |
8232 | * |
8233 | * Also calculates the amount of weighted load which should be moved | |
8234 | * to restore balance. | |
8235 | * | |
cd96891d | 8236 | * @env: The load balancing environment. |
1e3c88bd | 8237 | * |
e69f6186 | 8238 | * Return: - The busiest group if imbalance exists. |
1e3c88bd | 8239 | */ |
56cf515b | 8240 | static struct sched_group *find_busiest_group(struct lb_env *env) |
1e3c88bd | 8241 | { |
56cf515b | 8242 | struct sg_lb_stats *local, *busiest; |
1e3c88bd PZ |
8243 | struct sd_lb_stats sds; |
8244 | ||
147c5fc2 | 8245 | init_sd_lb_stats(&sds); |
1e3c88bd PZ |
8246 | |
8247 | /* | |
8248 | * Compute the various statistics relavent for load balancing at | |
8249 | * this level. | |
8250 | */ | |
23f0d209 | 8251 | update_sd_lb_stats(env, &sds); |
56cf515b JK |
8252 | local = &sds.local_stat; |
8253 | busiest = &sds.busiest_stat; | |
1e3c88bd | 8254 | |
ea67821b | 8255 | /* ASYM feature bypasses nice load balance check */ |
1f621e02 | 8256 | if (check_asym_packing(env, &sds)) |
532cb4c4 MN |
8257 | return sds.busiest; |
8258 | ||
cc57aa8f | 8259 | /* There is no busy sibling group to pull tasks from */ |
56cf515b | 8260 | if (!sds.busiest || busiest->sum_nr_running == 0) |
1e3c88bd PZ |
8261 | goto out_balanced; |
8262 | ||
90001d67 | 8263 | /* XXX broken for overlapping NUMA groups */ |
ca8ce3d0 NP |
8264 | sds.avg_load = (SCHED_CAPACITY_SCALE * sds.total_load) |
8265 | / sds.total_capacity; | |
b0432d8f | 8266 | |
866ab43e PZ |
8267 | /* |
8268 | * If the busiest group is imbalanced the below checks don't | |
30ce5dab | 8269 | * work because they assume all things are equal, which typically |
866ab43e PZ |
8270 | * isn't true due to cpus_allowed constraints and the like. |
8271 | */ | |
caeb178c | 8272 | if (busiest->group_type == group_imbalanced) |
866ab43e PZ |
8273 | goto force_balance; |
8274 | ||
583ffd99 BJ |
8275 | /* |
8276 | * When dst_cpu is idle, prevent SMP nice and/or asymmetric group | |
8277 | * capacities from resulting in underutilization due to avg_load. | |
8278 | */ | |
8279 | if (env->idle != CPU_NOT_IDLE && group_has_capacity(env, local) && | |
ea67821b | 8280 | busiest->group_no_capacity) |
fab47622 NR |
8281 | goto force_balance; |
8282 | ||
cc57aa8f | 8283 | /* |
9c58c79a | 8284 | * If the local group is busier than the selected busiest group |
cc57aa8f PZ |
8285 | * don't try and pull any tasks. |
8286 | */ | |
56cf515b | 8287 | if (local->avg_load >= busiest->avg_load) |
1e3c88bd PZ |
8288 | goto out_balanced; |
8289 | ||
cc57aa8f PZ |
8290 | /* |
8291 | * Don't pull any tasks if this group is already above the domain | |
8292 | * average load. | |
8293 | */ | |
56cf515b | 8294 | if (local->avg_load >= sds.avg_load) |
1e3c88bd PZ |
8295 | goto out_balanced; |
8296 | ||
bd939f45 | 8297 | if (env->idle == CPU_IDLE) { |
aae6d3dd | 8298 | /* |
43f4d666 VG |
8299 | * This cpu is idle. If the busiest group is not overloaded |
8300 | * and there is no imbalance between this and busiest group | |
8301 | * wrt idle cpus, it is balanced. The imbalance becomes | |
8302 | * significant if the diff is greater than 1 otherwise we | |
8303 | * might end up to just move the imbalance on another group | |
aae6d3dd | 8304 | */ |
43f4d666 VG |
8305 | if ((busiest->group_type != group_overloaded) && |
8306 | (local->idle_cpus <= (busiest->idle_cpus + 1))) | |
aae6d3dd | 8307 | goto out_balanced; |
c186fafe PZ |
8308 | } else { |
8309 | /* | |
8310 | * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use | |
8311 | * imbalance_pct to be conservative. | |
8312 | */ | |
56cf515b JK |
8313 | if (100 * busiest->avg_load <= |
8314 | env->sd->imbalance_pct * local->avg_load) | |
c186fafe | 8315 | goto out_balanced; |
aae6d3dd | 8316 | } |
1e3c88bd | 8317 | |
fab47622 | 8318 | force_balance: |
1e3c88bd | 8319 | /* Looks like there is an imbalance. Compute it */ |
bd939f45 | 8320 | calculate_imbalance(env, &sds); |
1e3c88bd PZ |
8321 | return sds.busiest; |
8322 | ||
8323 | out_balanced: | |
bd939f45 | 8324 | env->imbalance = 0; |
1e3c88bd PZ |
8325 | return NULL; |
8326 | } | |
8327 | ||
8328 | /* | |
8329 | * find_busiest_queue - find the busiest runqueue among the cpus in group. | |
8330 | */ | |
bd939f45 | 8331 | static struct rq *find_busiest_queue(struct lb_env *env, |
b9403130 | 8332 | struct sched_group *group) |
1e3c88bd PZ |
8333 | { |
8334 | struct rq *busiest = NULL, *rq; | |
ced549fa | 8335 | unsigned long busiest_load = 0, busiest_capacity = 1; |
1e3c88bd PZ |
8336 | int i; |
8337 | ||
ae4df9d6 | 8338 | for_each_cpu_and(i, sched_group_span(group), env->cpus) { |
ea67821b | 8339 | unsigned long capacity, wl; |
0ec8aa00 PZ |
8340 | enum fbq_type rt; |
8341 | ||
8342 | rq = cpu_rq(i); | |
8343 | rt = fbq_classify_rq(rq); | |
1e3c88bd | 8344 | |
0ec8aa00 PZ |
8345 | /* |
8346 | * We classify groups/runqueues into three groups: | |
8347 | * - regular: there are !numa tasks | |
8348 | * - remote: there are numa tasks that run on the 'wrong' node | |
8349 | * - all: there is no distinction | |
8350 | * | |
8351 | * In order to avoid migrating ideally placed numa tasks, | |
8352 | * ignore those when there's better options. | |
8353 | * | |
8354 | * If we ignore the actual busiest queue to migrate another | |
8355 | * task, the next balance pass can still reduce the busiest | |
8356 | * queue by moving tasks around inside the node. | |
8357 | * | |
8358 | * If we cannot move enough load due to this classification | |
8359 | * the next pass will adjust the group classification and | |
8360 | * allow migration of more tasks. | |
8361 | * | |
8362 | * Both cases only affect the total convergence complexity. | |
8363 | */ | |
8364 | if (rt > env->fbq_type) | |
8365 | continue; | |
8366 | ||
ced549fa | 8367 | capacity = capacity_of(i); |
9d5efe05 | 8368 | |
c7132dd6 | 8369 | wl = weighted_cpuload(rq); |
1e3c88bd | 8370 | |
6e40f5bb TG |
8371 | /* |
8372 | * When comparing with imbalance, use weighted_cpuload() | |
ced549fa | 8373 | * which is not scaled with the cpu capacity. |
6e40f5bb | 8374 | */ |
ea67821b VG |
8375 | |
8376 | if (rq->nr_running == 1 && wl > env->imbalance && | |
8377 | !check_cpu_capacity(rq, env->sd)) | |
1e3c88bd PZ |
8378 | continue; |
8379 | ||
6e40f5bb TG |
8380 | /* |
8381 | * For the load comparisons with the other cpu's, consider | |
ced549fa NP |
8382 | * the weighted_cpuload() scaled with the cpu capacity, so |
8383 | * that the load can be moved away from the cpu that is | |
8384 | * potentially running at a lower capacity. | |
95a79b80 | 8385 | * |
ced549fa | 8386 | * Thus we're looking for max(wl_i / capacity_i), crosswise |
95a79b80 | 8387 | * multiplication to rid ourselves of the division works out |
ced549fa NP |
8388 | * to: wl_i * capacity_j > wl_j * capacity_i; where j is |
8389 | * our previous maximum. | |
6e40f5bb | 8390 | */ |
ced549fa | 8391 | if (wl * busiest_capacity > busiest_load * capacity) { |
95a79b80 | 8392 | busiest_load = wl; |
ced549fa | 8393 | busiest_capacity = capacity; |
1e3c88bd PZ |
8394 | busiest = rq; |
8395 | } | |
8396 | } | |
8397 | ||
8398 | return busiest; | |
8399 | } | |
8400 | ||
8401 | /* | |
8402 | * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but | |
8403 | * so long as it is large enough. | |
8404 | */ | |
8405 | #define MAX_PINNED_INTERVAL 512 | |
8406 | ||
bd939f45 | 8407 | static int need_active_balance(struct lb_env *env) |
1af3ed3d | 8408 | { |
bd939f45 PZ |
8409 | struct sched_domain *sd = env->sd; |
8410 | ||
8411 | if (env->idle == CPU_NEWLY_IDLE) { | |
532cb4c4 MN |
8412 | |
8413 | /* | |
8414 | * ASYM_PACKING needs to force migrate tasks from busy but | |
afe06efd TC |
8415 | * lower priority CPUs in order to pack all tasks in the |
8416 | * highest priority CPUs. | |
532cb4c4 | 8417 | */ |
afe06efd TC |
8418 | if ((sd->flags & SD_ASYM_PACKING) && |
8419 | sched_asym_prefer(env->dst_cpu, env->src_cpu)) | |
532cb4c4 | 8420 | return 1; |
1af3ed3d PZ |
8421 | } |
8422 | ||
1aaf90a4 VG |
8423 | /* |
8424 | * The dst_cpu is idle and the src_cpu CPU has only 1 CFS task. | |
8425 | * It's worth migrating the task if the src_cpu's capacity is reduced | |
8426 | * because of other sched_class or IRQs if more capacity stays | |
8427 | * available on dst_cpu. | |
8428 | */ | |
8429 | if ((env->idle != CPU_NOT_IDLE) && | |
8430 | (env->src_rq->cfs.h_nr_running == 1)) { | |
8431 | if ((check_cpu_capacity(env->src_rq, sd)) && | |
8432 | (capacity_of(env->src_cpu)*sd->imbalance_pct < capacity_of(env->dst_cpu)*100)) | |
8433 | return 1; | |
8434 | } | |
8435 | ||
1af3ed3d PZ |
8436 | return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2); |
8437 | } | |
8438 | ||
969c7921 TH |
8439 | static int active_load_balance_cpu_stop(void *data); |
8440 | ||
23f0d209 JK |
8441 | static int should_we_balance(struct lb_env *env) |
8442 | { | |
8443 | struct sched_group *sg = env->sd->groups; | |
23f0d209 JK |
8444 | int cpu, balance_cpu = -1; |
8445 | ||
024c9d2f PZ |
8446 | /* |
8447 | * Ensure the balancing environment is consistent; can happen | |
8448 | * when the softirq triggers 'during' hotplug. | |
8449 | */ | |
8450 | if (!cpumask_test_cpu(env->dst_cpu, env->cpus)) | |
8451 | return 0; | |
8452 | ||
23f0d209 JK |
8453 | /* |
8454 | * In the newly idle case, we will allow all the cpu's | |
8455 | * to do the newly idle load balance. | |
8456 | */ | |
8457 | if (env->idle == CPU_NEWLY_IDLE) | |
8458 | return 1; | |
8459 | ||
23f0d209 | 8460 | /* Try to find first idle cpu */ |
e5c14b1f | 8461 | for_each_cpu_and(cpu, group_balance_mask(sg), env->cpus) { |
af218122 | 8462 | if (!idle_cpu(cpu)) |
23f0d209 JK |
8463 | continue; |
8464 | ||
8465 | balance_cpu = cpu; | |
8466 | break; | |
8467 | } | |
8468 | ||
8469 | if (balance_cpu == -1) | |
8470 | balance_cpu = group_balance_cpu(sg); | |
8471 | ||
8472 | /* | |
8473 | * First idle cpu or the first cpu(busiest) in this sched group | |
8474 | * is eligible for doing load balancing at this and above domains. | |
8475 | */ | |
b0cff9d8 | 8476 | return balance_cpu == env->dst_cpu; |
23f0d209 JK |
8477 | } |
8478 | ||
1e3c88bd PZ |
8479 | /* |
8480 | * Check this_cpu to ensure it is balanced within domain. Attempt to move | |
8481 | * tasks if there is an imbalance. | |
8482 | */ | |
8483 | static int load_balance(int this_cpu, struct rq *this_rq, | |
8484 | struct sched_domain *sd, enum cpu_idle_type idle, | |
23f0d209 | 8485 | int *continue_balancing) |
1e3c88bd | 8486 | { |
88b8dac0 | 8487 | int ld_moved, cur_ld_moved, active_balance = 0; |
6263322c | 8488 | struct sched_domain *sd_parent = sd->parent; |
1e3c88bd | 8489 | struct sched_group *group; |
1e3c88bd | 8490 | struct rq *busiest; |
8a8c69c3 | 8491 | struct rq_flags rf; |
4ba29684 | 8492 | struct cpumask *cpus = this_cpu_cpumask_var_ptr(load_balance_mask); |
1e3c88bd | 8493 | |
8e45cb54 PZ |
8494 | struct lb_env env = { |
8495 | .sd = sd, | |
ddcdf6e7 PZ |
8496 | .dst_cpu = this_cpu, |
8497 | .dst_rq = this_rq, | |
ae4df9d6 | 8498 | .dst_grpmask = sched_group_span(sd->groups), |
8e45cb54 | 8499 | .idle = idle, |
eb95308e | 8500 | .loop_break = sched_nr_migrate_break, |
b9403130 | 8501 | .cpus = cpus, |
0ec8aa00 | 8502 | .fbq_type = all, |
163122b7 | 8503 | .tasks = LIST_HEAD_INIT(env.tasks), |
8e45cb54 PZ |
8504 | }; |
8505 | ||
65a4433a | 8506 | cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask); |
1e3c88bd | 8507 | |
ae92882e | 8508 | schedstat_inc(sd->lb_count[idle]); |
1e3c88bd PZ |
8509 | |
8510 | redo: | |
23f0d209 JK |
8511 | if (!should_we_balance(&env)) { |
8512 | *continue_balancing = 0; | |
1e3c88bd | 8513 | goto out_balanced; |
23f0d209 | 8514 | } |
1e3c88bd | 8515 | |
23f0d209 | 8516 | group = find_busiest_group(&env); |
1e3c88bd | 8517 | if (!group) { |
ae92882e | 8518 | schedstat_inc(sd->lb_nobusyg[idle]); |
1e3c88bd PZ |
8519 | goto out_balanced; |
8520 | } | |
8521 | ||
b9403130 | 8522 | busiest = find_busiest_queue(&env, group); |
1e3c88bd | 8523 | if (!busiest) { |
ae92882e | 8524 | schedstat_inc(sd->lb_nobusyq[idle]); |
1e3c88bd PZ |
8525 | goto out_balanced; |
8526 | } | |
8527 | ||
78feefc5 | 8528 | BUG_ON(busiest == env.dst_rq); |
1e3c88bd | 8529 | |
ae92882e | 8530 | schedstat_add(sd->lb_imbalance[idle], env.imbalance); |
1e3c88bd | 8531 | |
1aaf90a4 VG |
8532 | env.src_cpu = busiest->cpu; |
8533 | env.src_rq = busiest; | |
8534 | ||
1e3c88bd PZ |
8535 | ld_moved = 0; |
8536 | if (busiest->nr_running > 1) { | |
8537 | /* | |
8538 | * Attempt to move tasks. If find_busiest_group has found | |
8539 | * an imbalance but busiest->nr_running <= 1, the group is | |
8540 | * still unbalanced. ld_moved simply stays zero, so it is | |
8541 | * correctly treated as an imbalance. | |
8542 | */ | |
8e45cb54 | 8543 | env.flags |= LBF_ALL_PINNED; |
c82513e5 | 8544 | env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running); |
8e45cb54 | 8545 | |
5d6523eb | 8546 | more_balance: |
8a8c69c3 | 8547 | rq_lock_irqsave(busiest, &rf); |
3bed5e21 | 8548 | update_rq_clock(busiest); |
88b8dac0 SV |
8549 | |
8550 | /* | |
8551 | * cur_ld_moved - load moved in current iteration | |
8552 | * ld_moved - cumulative load moved across iterations | |
8553 | */ | |
163122b7 | 8554 | cur_ld_moved = detach_tasks(&env); |
1e3c88bd PZ |
8555 | |
8556 | /* | |
163122b7 KT |
8557 | * We've detached some tasks from busiest_rq. Every |
8558 | * task is masked "TASK_ON_RQ_MIGRATING", so we can safely | |
8559 | * unlock busiest->lock, and we are able to be sure | |
8560 | * that nobody can manipulate the tasks in parallel. | |
8561 | * See task_rq_lock() family for the details. | |
1e3c88bd | 8562 | */ |
163122b7 | 8563 | |
8a8c69c3 | 8564 | rq_unlock(busiest, &rf); |
163122b7 KT |
8565 | |
8566 | if (cur_ld_moved) { | |
8567 | attach_tasks(&env); | |
8568 | ld_moved += cur_ld_moved; | |
8569 | } | |
8570 | ||
8a8c69c3 | 8571 | local_irq_restore(rf.flags); |
88b8dac0 | 8572 | |
f1cd0858 JK |
8573 | if (env.flags & LBF_NEED_BREAK) { |
8574 | env.flags &= ~LBF_NEED_BREAK; | |
8575 | goto more_balance; | |
8576 | } | |
8577 | ||
88b8dac0 SV |
8578 | /* |
8579 | * Revisit (affine) tasks on src_cpu that couldn't be moved to | |
8580 | * us and move them to an alternate dst_cpu in our sched_group | |
8581 | * where they can run. The upper limit on how many times we | |
8582 | * iterate on same src_cpu is dependent on number of cpus in our | |
8583 | * sched_group. | |
8584 | * | |
8585 | * This changes load balance semantics a bit on who can move | |
8586 | * load to a given_cpu. In addition to the given_cpu itself | |
8587 | * (or a ilb_cpu acting on its behalf where given_cpu is | |
8588 | * nohz-idle), we now have balance_cpu in a position to move | |
8589 | * load to given_cpu. In rare situations, this may cause | |
8590 | * conflicts (balance_cpu and given_cpu/ilb_cpu deciding | |
8591 | * _independently_ and at _same_ time to move some load to | |
8592 | * given_cpu) causing exceess load to be moved to given_cpu. | |
8593 | * This however should not happen so much in practice and | |
8594 | * moreover subsequent load balance cycles should correct the | |
8595 | * excess load moved. | |
8596 | */ | |
6263322c | 8597 | if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) { |
88b8dac0 | 8598 | |
7aff2e3a VD |
8599 | /* Prevent to re-select dst_cpu via env's cpus */ |
8600 | cpumask_clear_cpu(env.dst_cpu, env.cpus); | |
8601 | ||
78feefc5 | 8602 | env.dst_rq = cpu_rq(env.new_dst_cpu); |
88b8dac0 | 8603 | env.dst_cpu = env.new_dst_cpu; |
6263322c | 8604 | env.flags &= ~LBF_DST_PINNED; |
88b8dac0 SV |
8605 | env.loop = 0; |
8606 | env.loop_break = sched_nr_migrate_break; | |
e02e60c1 | 8607 | |
88b8dac0 SV |
8608 | /* |
8609 | * Go back to "more_balance" rather than "redo" since we | |
8610 | * need to continue with same src_cpu. | |
8611 | */ | |
8612 | goto more_balance; | |
8613 | } | |
1e3c88bd | 8614 | |
6263322c PZ |
8615 | /* |
8616 | * We failed to reach balance because of affinity. | |
8617 | */ | |
8618 | if (sd_parent) { | |
63b2ca30 | 8619 | int *group_imbalance = &sd_parent->groups->sgc->imbalance; |
6263322c | 8620 | |
afdeee05 | 8621 | if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) |
6263322c | 8622 | *group_imbalance = 1; |
6263322c PZ |
8623 | } |
8624 | ||
1e3c88bd | 8625 | /* All tasks on this runqueue were pinned by CPU affinity */ |
8e45cb54 | 8626 | if (unlikely(env.flags & LBF_ALL_PINNED)) { |
1e3c88bd | 8627 | cpumask_clear_cpu(cpu_of(busiest), cpus); |
65a4433a JH |
8628 | /* |
8629 | * Attempting to continue load balancing at the current | |
8630 | * sched_domain level only makes sense if there are | |
8631 | * active CPUs remaining as possible busiest CPUs to | |
8632 | * pull load from which are not contained within the | |
8633 | * destination group that is receiving any migrated | |
8634 | * load. | |
8635 | */ | |
8636 | if (!cpumask_subset(cpus, env.dst_grpmask)) { | |
bbf18b19 PN |
8637 | env.loop = 0; |
8638 | env.loop_break = sched_nr_migrate_break; | |
1e3c88bd | 8639 | goto redo; |
bbf18b19 | 8640 | } |
afdeee05 | 8641 | goto out_all_pinned; |
1e3c88bd PZ |
8642 | } |
8643 | } | |
8644 | ||
8645 | if (!ld_moved) { | |
ae92882e | 8646 | schedstat_inc(sd->lb_failed[idle]); |
58b26c4c VP |
8647 | /* |
8648 | * Increment the failure counter only on periodic balance. | |
8649 | * We do not want newidle balance, which can be very | |
8650 | * frequent, pollute the failure counter causing | |
8651 | * excessive cache_hot migrations and active balances. | |
8652 | */ | |
8653 | if (idle != CPU_NEWLY_IDLE) | |
8654 | sd->nr_balance_failed++; | |
1e3c88bd | 8655 | |
bd939f45 | 8656 | if (need_active_balance(&env)) { |
8a8c69c3 PZ |
8657 | unsigned long flags; |
8658 | ||
1e3c88bd PZ |
8659 | raw_spin_lock_irqsave(&busiest->lock, flags); |
8660 | ||
969c7921 TH |
8661 | /* don't kick the active_load_balance_cpu_stop, |
8662 | * if the curr task on busiest cpu can't be | |
8663 | * moved to this_cpu | |
1e3c88bd | 8664 | */ |
0c98d344 | 8665 | if (!cpumask_test_cpu(this_cpu, &busiest->curr->cpus_allowed)) { |
1e3c88bd PZ |
8666 | raw_spin_unlock_irqrestore(&busiest->lock, |
8667 | flags); | |
8e45cb54 | 8668 | env.flags |= LBF_ALL_PINNED; |
1e3c88bd PZ |
8669 | goto out_one_pinned; |
8670 | } | |
8671 | ||
969c7921 TH |
8672 | /* |
8673 | * ->active_balance synchronizes accesses to | |
8674 | * ->active_balance_work. Once set, it's cleared | |
8675 | * only after active load balance is finished. | |
8676 | */ | |
1e3c88bd PZ |
8677 | if (!busiest->active_balance) { |
8678 | busiest->active_balance = 1; | |
8679 | busiest->push_cpu = this_cpu; | |
8680 | active_balance = 1; | |
8681 | } | |
8682 | raw_spin_unlock_irqrestore(&busiest->lock, flags); | |
969c7921 | 8683 | |
bd939f45 | 8684 | if (active_balance) { |
969c7921 TH |
8685 | stop_one_cpu_nowait(cpu_of(busiest), |
8686 | active_load_balance_cpu_stop, busiest, | |
8687 | &busiest->active_balance_work); | |
bd939f45 | 8688 | } |
1e3c88bd | 8689 | |
d02c0711 | 8690 | /* We've kicked active balancing, force task migration. */ |
1e3c88bd PZ |
8691 | sd->nr_balance_failed = sd->cache_nice_tries+1; |
8692 | } | |
8693 | } else | |
8694 | sd->nr_balance_failed = 0; | |
8695 | ||
8696 | if (likely(!active_balance)) { | |
8697 | /* We were unbalanced, so reset the balancing interval */ | |
8698 | sd->balance_interval = sd->min_interval; | |
8699 | } else { | |
8700 | /* | |
8701 | * If we've begun active balancing, start to back off. This | |
8702 | * case may not be covered by the all_pinned logic if there | |
8703 | * is only 1 task on the busy runqueue (because we don't call | |
163122b7 | 8704 | * detach_tasks). |
1e3c88bd PZ |
8705 | */ |
8706 | if (sd->balance_interval < sd->max_interval) | |
8707 | sd->balance_interval *= 2; | |
8708 | } | |
8709 | ||
1e3c88bd PZ |
8710 | goto out; |
8711 | ||
8712 | out_balanced: | |
afdeee05 VG |
8713 | /* |
8714 | * We reach balance although we may have faced some affinity | |
e285924d VG |
8715 | * constraints. Clear the imbalance flag only if other tasks got |
8716 | * a chance to move and fix the imbalance. | |
afdeee05 | 8717 | */ |
e285924d | 8718 | if (sd_parent && !(env.flags & LBF_ALL_PINNED)) { |
afdeee05 VG |
8719 | int *group_imbalance = &sd_parent->groups->sgc->imbalance; |
8720 | ||
8721 | if (*group_imbalance) | |
8722 | *group_imbalance = 0; | |
8723 | } | |
8724 | ||
8725 | out_all_pinned: | |
8726 | /* | |
8727 | * We reach balance because all tasks are pinned at this level so | |
8728 | * we can't migrate them. Let the imbalance flag set so parent level | |
8729 | * can try to migrate them. | |
8730 | */ | |
ae92882e | 8731 | schedstat_inc(sd->lb_balanced[idle]); |
1e3c88bd PZ |
8732 | |
8733 | sd->nr_balance_failed = 0; | |
8734 | ||
8735 | out_one_pinned: | |
6255133d VS |
8736 | ld_moved = 0; |
8737 | ||
8738 | /* | |
8739 | * idle_balance() disregards balance intervals, so we could repeatedly | |
8740 | * reach this code, which would lead to balance_interval skyrocketting | |
8741 | * in a short amount of time. Skip the balance_interval increase logic | |
8742 | * to avoid that. | |
8743 | */ | |
8744 | if (env.idle == CPU_NEWLY_IDLE) | |
8745 | goto out; | |
8746 | ||
1e3c88bd | 8747 | /* tune up the balancing interval */ |
8e45cb54 | 8748 | if (((env.flags & LBF_ALL_PINNED) && |
5b54b56b | 8749 | sd->balance_interval < MAX_PINNED_INTERVAL) || |
1e3c88bd PZ |
8750 | (sd->balance_interval < sd->max_interval)) |
8751 | sd->balance_interval *= 2; | |
1e3c88bd | 8752 | out: |
1e3c88bd PZ |
8753 | return ld_moved; |
8754 | } | |
8755 | ||
52a08ef1 JL |
8756 | static inline unsigned long |
8757 | get_sd_balance_interval(struct sched_domain *sd, int cpu_busy) | |
8758 | { | |
8759 | unsigned long interval = sd->balance_interval; | |
8760 | ||
8761 | if (cpu_busy) | |
8762 | interval *= sd->busy_factor; | |
8763 | ||
8764 | /* scale ms to jiffies */ | |
8765 | interval = msecs_to_jiffies(interval); | |
8766 | interval = clamp(interval, 1UL, max_load_balance_interval); | |
8767 | ||
8768 | return interval; | |
8769 | } | |
8770 | ||
8771 | static inline void | |
31851a98 | 8772 | update_next_balance(struct sched_domain *sd, unsigned long *next_balance) |
52a08ef1 JL |
8773 | { |
8774 | unsigned long interval, next; | |
8775 | ||
31851a98 LY |
8776 | /* used by idle balance, so cpu_busy = 0 */ |
8777 | interval = get_sd_balance_interval(sd, 0); | |
52a08ef1 JL |
8778 | next = sd->last_balance + interval; |
8779 | ||
8780 | if (time_after(*next_balance, next)) | |
8781 | *next_balance = next; | |
8782 | } | |
8783 | ||
1e3c88bd PZ |
8784 | /* |
8785 | * idle_balance is called by schedule() if this_cpu is about to become | |
8786 | * idle. Attempts to pull tasks from other CPUs. | |
8787 | */ | |
46f69fa3 | 8788 | static int idle_balance(struct rq *this_rq, struct rq_flags *rf) |
1e3c88bd | 8789 | { |
52a08ef1 JL |
8790 | unsigned long next_balance = jiffies + HZ; |
8791 | int this_cpu = this_rq->cpu; | |
1e3c88bd PZ |
8792 | struct sched_domain *sd; |
8793 | int pulled_task = 0; | |
9bd721c5 | 8794 | u64 curr_cost = 0; |
1e3c88bd | 8795 | |
6e83125c PZ |
8796 | /* |
8797 | * We must set idle_stamp _before_ calling idle_balance(), such that we | |
8798 | * measure the duration of idle_balance() as idle time. | |
8799 | */ | |
8800 | this_rq->idle_stamp = rq_clock(this_rq); | |
8801 | ||
2800486e PZ |
8802 | /* |
8803 | * Do not pull tasks towards !active CPUs... | |
8804 | */ | |
8805 | if (!cpu_active(this_cpu)) | |
8806 | return 0; | |
8807 | ||
46f69fa3 MF |
8808 | /* |
8809 | * This is OK, because current is on_cpu, which avoids it being picked | |
8810 | * for load-balance and preemption/IRQs are still disabled avoiding | |
8811 | * further scheduler activity on it and we're being very careful to | |
8812 | * re-start the picking loop. | |
8813 | */ | |
8814 | rq_unpin_lock(this_rq, rf); | |
8815 | ||
4486edd1 TC |
8816 | if (this_rq->avg_idle < sysctl_sched_migration_cost || |
8817 | !this_rq->rd->overload) { | |
52a08ef1 JL |
8818 | rcu_read_lock(); |
8819 | sd = rcu_dereference_check_sched_domain(this_rq->sd); | |
8820 | if (sd) | |
31851a98 | 8821 | update_next_balance(sd, &next_balance); |
52a08ef1 JL |
8822 | rcu_read_unlock(); |
8823 | ||
6e83125c | 8824 | goto out; |
52a08ef1 | 8825 | } |
1e3c88bd | 8826 | |
f492e12e PZ |
8827 | raw_spin_unlock(&this_rq->lock); |
8828 | ||
48a16753 | 8829 | update_blocked_averages(this_cpu); |
dce840a0 | 8830 | rcu_read_lock(); |
1e3c88bd | 8831 | for_each_domain(this_cpu, sd) { |
23f0d209 | 8832 | int continue_balancing = 1; |
9bd721c5 | 8833 | u64 t0, domain_cost; |
1e3c88bd PZ |
8834 | |
8835 | if (!(sd->flags & SD_LOAD_BALANCE)) | |
8836 | continue; | |
8837 | ||
52a08ef1 | 8838 | if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) { |
31851a98 | 8839 | update_next_balance(sd, &next_balance); |
9bd721c5 | 8840 | break; |
52a08ef1 | 8841 | } |
9bd721c5 | 8842 | |
f492e12e | 8843 | if (sd->flags & SD_BALANCE_NEWIDLE) { |
9bd721c5 JL |
8844 | t0 = sched_clock_cpu(this_cpu); |
8845 | ||
f492e12e | 8846 | pulled_task = load_balance(this_cpu, this_rq, |
23f0d209 JK |
8847 | sd, CPU_NEWLY_IDLE, |
8848 | &continue_balancing); | |
9bd721c5 JL |
8849 | |
8850 | domain_cost = sched_clock_cpu(this_cpu) - t0; | |
8851 | if (domain_cost > sd->max_newidle_lb_cost) | |
8852 | sd->max_newidle_lb_cost = domain_cost; | |
8853 | ||
8854 | curr_cost += domain_cost; | |
f492e12e | 8855 | } |
1e3c88bd | 8856 | |
31851a98 | 8857 | update_next_balance(sd, &next_balance); |
39a4d9ca JL |
8858 | |
8859 | /* | |
8860 | * Stop searching for tasks to pull if there are | |
8861 | * now runnable tasks on this rq. | |
8862 | */ | |
8863 | if (pulled_task || this_rq->nr_running > 0) | |
1e3c88bd | 8864 | break; |
1e3c88bd | 8865 | } |
dce840a0 | 8866 | rcu_read_unlock(); |
f492e12e PZ |
8867 | |
8868 | raw_spin_lock(&this_rq->lock); | |
8869 | ||
0e5b5337 JL |
8870 | if (curr_cost > this_rq->max_idle_balance_cost) |
8871 | this_rq->max_idle_balance_cost = curr_cost; | |
8872 | ||
e5fc6611 | 8873 | /* |
0e5b5337 JL |
8874 | * While browsing the domains, we released the rq lock, a task could |
8875 | * have been enqueued in the meantime. Since we're not going idle, | |
8876 | * pretend we pulled a task. | |
e5fc6611 | 8877 | */ |
0e5b5337 | 8878 | if (this_rq->cfs.h_nr_running && !pulled_task) |
6e83125c | 8879 | pulled_task = 1; |
e5fc6611 | 8880 | |
52a08ef1 JL |
8881 | out: |
8882 | /* Move the next balance forward */ | |
8883 | if (time_after(this_rq->next_balance, next_balance)) | |
1e3c88bd | 8884 | this_rq->next_balance = next_balance; |
9bd721c5 | 8885 | |
e4aa358b | 8886 | /* Is there a task of a high priority class? */ |
46383648 | 8887 | if (this_rq->nr_running != this_rq->cfs.h_nr_running) |
e4aa358b KT |
8888 | pulled_task = -1; |
8889 | ||
38c6ade2 | 8890 | if (pulled_task) |
6e83125c PZ |
8891 | this_rq->idle_stamp = 0; |
8892 | ||
46f69fa3 MF |
8893 | rq_repin_lock(this_rq, rf); |
8894 | ||
3c4017c1 | 8895 | return pulled_task; |
1e3c88bd PZ |
8896 | } |
8897 | ||
8898 | /* | |
969c7921 TH |
8899 | * active_load_balance_cpu_stop is run by cpu stopper. It pushes |
8900 | * running tasks off the busiest CPU onto idle CPUs. It requires at | |
8901 | * least 1 task to be running on each physical CPU where possible, and | |
8902 | * avoids physical / logical imbalances. | |
1e3c88bd | 8903 | */ |
969c7921 | 8904 | static int active_load_balance_cpu_stop(void *data) |
1e3c88bd | 8905 | { |
969c7921 TH |
8906 | struct rq *busiest_rq = data; |
8907 | int busiest_cpu = cpu_of(busiest_rq); | |
1e3c88bd | 8908 | int target_cpu = busiest_rq->push_cpu; |
969c7921 | 8909 | struct rq *target_rq = cpu_rq(target_cpu); |
1e3c88bd | 8910 | struct sched_domain *sd; |
e5673f28 | 8911 | struct task_struct *p = NULL; |
8a8c69c3 | 8912 | struct rq_flags rf; |
969c7921 | 8913 | |
8a8c69c3 | 8914 | rq_lock_irq(busiest_rq, &rf); |
edd8e41d PZ |
8915 | /* |
8916 | * Between queueing the stop-work and running it is a hole in which | |
8917 | * CPUs can become inactive. We should not move tasks from or to | |
8918 | * inactive CPUs. | |
8919 | */ | |
8920 | if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu)) | |
8921 | goto out_unlock; | |
969c7921 TH |
8922 | |
8923 | /* make sure the requested cpu hasn't gone down in the meantime */ | |
8924 | if (unlikely(busiest_cpu != smp_processor_id() || | |
8925 | !busiest_rq->active_balance)) | |
8926 | goto out_unlock; | |
1e3c88bd PZ |
8927 | |
8928 | /* Is there any task to move? */ | |
8929 | if (busiest_rq->nr_running <= 1) | |
969c7921 | 8930 | goto out_unlock; |
1e3c88bd PZ |
8931 | |
8932 | /* | |
8933 | * This condition is "impossible", if it occurs | |
8934 | * we need to fix it. Originally reported by | |
8935 | * Bjorn Helgaas on a 128-cpu setup. | |
8936 | */ | |
8937 | BUG_ON(busiest_rq == target_rq); | |
8938 | ||
1e3c88bd | 8939 | /* Search for an sd spanning us and the target CPU. */ |
dce840a0 | 8940 | rcu_read_lock(); |
1e3c88bd PZ |
8941 | for_each_domain(target_cpu, sd) { |
8942 | if ((sd->flags & SD_LOAD_BALANCE) && | |
8943 | cpumask_test_cpu(busiest_cpu, sched_domain_span(sd))) | |
8944 | break; | |
8945 | } | |
8946 | ||
8947 | if (likely(sd)) { | |
8e45cb54 PZ |
8948 | struct lb_env env = { |
8949 | .sd = sd, | |
ddcdf6e7 PZ |
8950 | .dst_cpu = target_cpu, |
8951 | .dst_rq = target_rq, | |
8952 | .src_cpu = busiest_rq->cpu, | |
8953 | .src_rq = busiest_rq, | |
8e45cb54 | 8954 | .idle = CPU_IDLE, |
65a4433a JH |
8955 | /* |
8956 | * can_migrate_task() doesn't need to compute new_dst_cpu | |
8957 | * for active balancing. Since we have CPU_IDLE, but no | |
8958 | * @dst_grpmask we need to make that test go away with lying | |
8959 | * about DST_PINNED. | |
8960 | */ | |
8961 | .flags = LBF_DST_PINNED, | |
8e45cb54 PZ |
8962 | }; |
8963 | ||
ae92882e | 8964 | schedstat_inc(sd->alb_count); |
3bed5e21 | 8965 | update_rq_clock(busiest_rq); |
1e3c88bd | 8966 | |
e5673f28 | 8967 | p = detach_one_task(&env); |
d02c0711 | 8968 | if (p) { |
ae92882e | 8969 | schedstat_inc(sd->alb_pushed); |
d02c0711 SD |
8970 | /* Active balancing done, reset the failure counter. */ |
8971 | sd->nr_balance_failed = 0; | |
8972 | } else { | |
ae92882e | 8973 | schedstat_inc(sd->alb_failed); |
d02c0711 | 8974 | } |
1e3c88bd | 8975 | } |
dce840a0 | 8976 | rcu_read_unlock(); |
969c7921 TH |
8977 | out_unlock: |
8978 | busiest_rq->active_balance = 0; | |
8a8c69c3 | 8979 | rq_unlock(busiest_rq, &rf); |
e5673f28 KT |
8980 | |
8981 | if (p) | |
8982 | attach_one_task(target_rq, p); | |
8983 | ||
8984 | local_irq_enable(); | |
8985 | ||
969c7921 | 8986 | return 0; |
1e3c88bd PZ |
8987 | } |
8988 | ||
d987fc7f MG |
8989 | static inline int on_null_domain(struct rq *rq) |
8990 | { | |
8991 | return unlikely(!rcu_dereference_sched(rq->sd)); | |
8992 | } | |
8993 | ||
3451d024 | 8994 | #ifdef CONFIG_NO_HZ_COMMON |
83cd4fe2 VP |
8995 | /* |
8996 | * idle load balancing details | |
83cd4fe2 VP |
8997 | * - When one of the busy CPUs notice that there may be an idle rebalancing |
8998 | * needed, they will kick the idle load balancer, which then does idle | |
8999 | * load balancing for all the idle CPUs. | |
2036ed18 NP |
9000 | * - HK_FLAG_MISC CPUs are used for this task, because HK_FLAG_SCHED not set |
9001 | * anywhere yet. | |
83cd4fe2 | 9002 | */ |
1e3c88bd | 9003 | static struct { |
83cd4fe2 | 9004 | cpumask_var_t idle_cpus_mask; |
0b005cf5 | 9005 | atomic_t nr_cpus; |
83cd4fe2 VP |
9006 | unsigned long next_balance; /* in jiffy units */ |
9007 | } nohz ____cacheline_aligned; | |
1e3c88bd | 9008 | |
3dd0337d | 9009 | static inline int find_new_ilb(void) |
1e3c88bd | 9010 | { |
2036ed18 | 9011 | int ilb; |
1e3c88bd | 9012 | |
2036ed18 NP |
9013 | for_each_cpu_and(ilb, nohz.idle_cpus_mask, |
9014 | housekeeping_cpumask(HK_FLAG_MISC)) { | |
9015 | if (idle_cpu(ilb)) | |
9016 | return ilb; | |
9017 | } | |
786d6dc7 SS |
9018 | |
9019 | return nr_cpu_ids; | |
1e3c88bd | 9020 | } |
1e3c88bd | 9021 | |
83cd4fe2 | 9022 | /* |
2036ed18 NP |
9023 | * Kick a CPU to do the nohz balancing, if it is time for it. We pick any |
9024 | * idle CPU in the HK_FLAG_MISC housekeeping set (if there is one). | |
83cd4fe2 | 9025 | */ |
0aeeeeba | 9026 | static void nohz_balancer_kick(void) |
83cd4fe2 VP |
9027 | { |
9028 | int ilb_cpu; | |
9029 | ||
9030 | nohz.next_balance++; | |
9031 | ||
3dd0337d | 9032 | ilb_cpu = find_new_ilb(); |
83cd4fe2 | 9033 | |
0b005cf5 SS |
9034 | if (ilb_cpu >= nr_cpu_ids) |
9035 | return; | |
83cd4fe2 | 9036 | |
cd490c5b | 9037 | if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu))) |
1c792db7 SS |
9038 | return; |
9039 | /* | |
9040 | * Use smp_send_reschedule() instead of resched_cpu(). | |
9041 | * This way we generate a sched IPI on the target cpu which | |
9042 | * is idle. And the softirq performing nohz idle load balance | |
9043 | * will be run before returning from the IPI. | |
9044 | */ | |
9045 | smp_send_reschedule(ilb_cpu); | |
83cd4fe2 VP |
9046 | return; |
9047 | } | |
9048 | ||
20a5c8cc | 9049 | void nohz_balance_exit_idle(unsigned int cpu) |
71325960 SS |
9050 | { |
9051 | if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) { | |
d987fc7f MG |
9052 | /* |
9053 | * Completely isolated CPUs don't ever set, so we must test. | |
9054 | */ | |
9055 | if (likely(cpumask_test_cpu(cpu, nohz.idle_cpus_mask))) { | |
9056 | cpumask_clear_cpu(cpu, nohz.idle_cpus_mask); | |
9057 | atomic_dec(&nohz.nr_cpus); | |
9058 | } | |
71325960 SS |
9059 | clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); |
9060 | } | |
9061 | } | |
9062 | ||
69e1e811 SS |
9063 | static inline void set_cpu_sd_state_busy(void) |
9064 | { | |
9065 | struct sched_domain *sd; | |
37dc6b50 | 9066 | int cpu = smp_processor_id(); |
69e1e811 | 9067 | |
69e1e811 | 9068 | rcu_read_lock(); |
0e369d75 | 9069 | sd = rcu_dereference(per_cpu(sd_llc, cpu)); |
25f55d9d VG |
9070 | |
9071 | if (!sd || !sd->nohz_idle) | |
9072 | goto unlock; | |
9073 | sd->nohz_idle = 0; | |
9074 | ||
0e369d75 | 9075 | atomic_inc(&sd->shared->nr_busy_cpus); |
25f55d9d | 9076 | unlock: |
69e1e811 SS |
9077 | rcu_read_unlock(); |
9078 | } | |
9079 | ||
9080 | void set_cpu_sd_state_idle(void) | |
9081 | { | |
9082 | struct sched_domain *sd; | |
37dc6b50 | 9083 | int cpu = smp_processor_id(); |
69e1e811 | 9084 | |
69e1e811 | 9085 | rcu_read_lock(); |
0e369d75 | 9086 | sd = rcu_dereference(per_cpu(sd_llc, cpu)); |
25f55d9d VG |
9087 | |
9088 | if (!sd || sd->nohz_idle) | |
9089 | goto unlock; | |
9090 | sd->nohz_idle = 1; | |
9091 | ||
0e369d75 | 9092 | atomic_dec(&sd->shared->nr_busy_cpus); |
25f55d9d | 9093 | unlock: |
69e1e811 SS |
9094 | rcu_read_unlock(); |
9095 | } | |
9096 | ||
1e3c88bd | 9097 | /* |
c1cc017c | 9098 | * This routine will record that the cpu is going idle with tick stopped. |
0b005cf5 | 9099 | * This info will be used in performing idle load balancing in the future. |
1e3c88bd | 9100 | */ |
c1cc017c | 9101 | void nohz_balance_enter_idle(int cpu) |
1e3c88bd | 9102 | { |
71325960 SS |
9103 | /* |
9104 | * If this cpu is going down, then nothing needs to be done. | |
9105 | */ | |
9106 | if (!cpu_active(cpu)) | |
9107 | return; | |
9108 | ||
387bc8b5 | 9109 | /* Spare idle load balancing on CPUs that don't want to be disturbed: */ |
de201559 | 9110 | if (!housekeeping_cpu(cpu, HK_FLAG_SCHED)) |
387bc8b5 FW |
9111 | return; |
9112 | ||
c1cc017c AS |
9113 | if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu))) |
9114 | return; | |
1e3c88bd | 9115 | |
d987fc7f MG |
9116 | /* |
9117 | * If we're a completely isolated CPU, we don't play. | |
9118 | */ | |
9119 | if (on_null_domain(cpu_rq(cpu))) | |
9120 | return; | |
9121 | ||
c1cc017c AS |
9122 | cpumask_set_cpu(cpu, nohz.idle_cpus_mask); |
9123 | atomic_inc(&nohz.nr_cpus); | |
9124 | set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); | |
1e3c88bd PZ |
9125 | } |
9126 | #endif | |
9127 | ||
9128 | static DEFINE_SPINLOCK(balancing); | |
9129 | ||
49c022e6 PZ |
9130 | /* |
9131 | * Scale the max load_balance interval with the number of CPUs in the system. | |
9132 | * This trades load-balance latency on larger machines for less cross talk. | |
9133 | */ | |
029632fb | 9134 | void update_max_interval(void) |
49c022e6 PZ |
9135 | { |
9136 | max_load_balance_interval = HZ*num_online_cpus()/10; | |
9137 | } | |
9138 | ||
1e3c88bd PZ |
9139 | /* |
9140 | * It checks each scheduling domain to see if it is due to be balanced, | |
9141 | * and initiates a balancing operation if so. | |
9142 | * | |
b9b0853a | 9143 | * Balancing parameters are set up in init_sched_domains. |
1e3c88bd | 9144 | */ |
f7ed0a89 | 9145 | static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) |
1e3c88bd | 9146 | { |
23f0d209 | 9147 | int continue_balancing = 1; |
f7ed0a89 | 9148 | int cpu = rq->cpu; |
1e3c88bd | 9149 | unsigned long interval; |
04f733b4 | 9150 | struct sched_domain *sd; |
1e3c88bd PZ |
9151 | /* Earliest time when we have to do rebalance again */ |
9152 | unsigned long next_balance = jiffies + 60*HZ; | |
9153 | int update_next_balance = 0; | |
f48627e6 JL |
9154 | int need_serialize, need_decay = 0; |
9155 | u64 max_cost = 0; | |
1e3c88bd | 9156 | |
48a16753 | 9157 | update_blocked_averages(cpu); |
2069dd75 | 9158 | |
dce840a0 | 9159 | rcu_read_lock(); |
1e3c88bd | 9160 | for_each_domain(cpu, sd) { |
f48627e6 JL |
9161 | /* |
9162 | * Decay the newidle max times here because this is a regular | |
9163 | * visit to all the domains. Decay ~1% per second. | |
9164 | */ | |
9165 | if (time_after(jiffies, sd->next_decay_max_lb_cost)) { | |
9166 | sd->max_newidle_lb_cost = | |
9167 | (sd->max_newidle_lb_cost * 253) / 256; | |
9168 | sd->next_decay_max_lb_cost = jiffies + HZ; | |
9169 | need_decay = 1; | |
9170 | } | |
9171 | max_cost += sd->max_newidle_lb_cost; | |
9172 | ||
1e3c88bd PZ |
9173 | if (!(sd->flags & SD_LOAD_BALANCE)) |
9174 | continue; | |
9175 | ||
f48627e6 JL |
9176 | /* |
9177 | * Stop the load balance at this level. There is another | |
9178 | * CPU in our sched group which is doing load balancing more | |
9179 | * actively. | |
9180 | */ | |
9181 | if (!continue_balancing) { | |
9182 | if (need_decay) | |
9183 | continue; | |
9184 | break; | |
9185 | } | |
9186 | ||
52a08ef1 | 9187 | interval = get_sd_balance_interval(sd, idle != CPU_IDLE); |
1e3c88bd PZ |
9188 | |
9189 | need_serialize = sd->flags & SD_SERIALIZE; | |
1e3c88bd PZ |
9190 | if (need_serialize) { |
9191 | if (!spin_trylock(&balancing)) | |
9192 | goto out; | |
9193 | } | |
9194 | ||
9195 | if (time_after_eq(jiffies, sd->last_balance + interval)) { | |
23f0d209 | 9196 | if (load_balance(cpu, rq, sd, idle, &continue_balancing)) { |
1e3c88bd | 9197 | /* |
6263322c | 9198 | * The LBF_DST_PINNED logic could have changed |
de5eb2dd JK |
9199 | * env->dst_cpu, so we can't know our idle |
9200 | * state even if we migrated tasks. Update it. | |
1e3c88bd | 9201 | */ |
de5eb2dd | 9202 | idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE; |
1e3c88bd PZ |
9203 | } |
9204 | sd->last_balance = jiffies; | |
52a08ef1 | 9205 | interval = get_sd_balance_interval(sd, idle != CPU_IDLE); |
1e3c88bd PZ |
9206 | } |
9207 | if (need_serialize) | |
9208 | spin_unlock(&balancing); | |
9209 | out: | |
9210 | if (time_after(next_balance, sd->last_balance + interval)) { | |
9211 | next_balance = sd->last_balance + interval; | |
9212 | update_next_balance = 1; | |
9213 | } | |
f48627e6 JL |
9214 | } |
9215 | if (need_decay) { | |
1e3c88bd | 9216 | /* |
f48627e6 JL |
9217 | * Ensure the rq-wide value also decays but keep it at a |
9218 | * reasonable floor to avoid funnies with rq->avg_idle. | |
1e3c88bd | 9219 | */ |
f48627e6 JL |
9220 | rq->max_idle_balance_cost = |
9221 | max((u64)sysctl_sched_migration_cost, max_cost); | |
1e3c88bd | 9222 | } |
dce840a0 | 9223 | rcu_read_unlock(); |
1e3c88bd PZ |
9224 | |
9225 | /* | |
9226 | * next_balance will be updated only when there is a need. | |
9227 | * When the cpu is attached to null domain for ex, it will not be | |
9228 | * updated. | |
9229 | */ | |
c5afb6a8 | 9230 | if (likely(update_next_balance)) { |
1e3c88bd | 9231 | rq->next_balance = next_balance; |
c5afb6a8 VG |
9232 | |
9233 | #ifdef CONFIG_NO_HZ_COMMON | |
9234 | /* | |
9235 | * If this CPU has been elected to perform the nohz idle | |
9236 | * balance. Other idle CPUs have already rebalanced with | |
9237 | * nohz_idle_balance() and nohz.next_balance has been | |
9238 | * updated accordingly. This CPU is now running the idle load | |
9239 | * balance for itself and we need to update the | |
9240 | * nohz.next_balance accordingly. | |
9241 | */ | |
9242 | if ((idle == CPU_IDLE) && time_after(nohz.next_balance, rq->next_balance)) | |
9243 | nohz.next_balance = rq->next_balance; | |
9244 | #endif | |
9245 | } | |
1e3c88bd PZ |
9246 | } |
9247 | ||
3451d024 | 9248 | #ifdef CONFIG_NO_HZ_COMMON |
1e3c88bd | 9249 | /* |
3451d024 | 9250 | * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the |
1e3c88bd PZ |
9251 | * rebalancing for all the cpus for whom scheduler ticks are stopped. |
9252 | */ | |
208cb16b | 9253 | static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) |
83cd4fe2 | 9254 | { |
208cb16b | 9255 | int this_cpu = this_rq->cpu; |
83cd4fe2 VP |
9256 | struct rq *rq; |
9257 | int balance_cpu; | |
c5afb6a8 VG |
9258 | /* Earliest time when we have to do rebalance again */ |
9259 | unsigned long next_balance = jiffies + 60*HZ; | |
9260 | int update_next_balance = 0; | |
83cd4fe2 | 9261 | |
1c792db7 SS |
9262 | if (idle != CPU_IDLE || |
9263 | !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu))) | |
9264 | goto end; | |
83cd4fe2 VP |
9265 | |
9266 | for_each_cpu(balance_cpu, nohz.idle_cpus_mask) { | |
8a6d42d1 | 9267 | if (balance_cpu == this_cpu || !idle_cpu(balance_cpu)) |
83cd4fe2 VP |
9268 | continue; |
9269 | ||
9270 | /* | |
9271 | * If this cpu gets work to do, stop the load balancing | |
9272 | * work being done for other cpus. Next load | |
9273 | * balancing owner will pick it up. | |
9274 | */ | |
1c792db7 | 9275 | if (need_resched()) |
83cd4fe2 | 9276 | break; |
83cd4fe2 | 9277 | |
5ed4f1d9 VG |
9278 | rq = cpu_rq(balance_cpu); |
9279 | ||
ed61bbc6 TC |
9280 | /* |
9281 | * If time for next balance is due, | |
9282 | * do the balance. | |
9283 | */ | |
9284 | if (time_after_eq(jiffies, rq->next_balance)) { | |
8a8c69c3 PZ |
9285 | struct rq_flags rf; |
9286 | ||
9287 | rq_lock_irq(rq, &rf); | |
ed61bbc6 | 9288 | update_rq_clock(rq); |
cee1afce | 9289 | cpu_load_update_idle(rq); |
8a8c69c3 PZ |
9290 | rq_unlock_irq(rq, &rf); |
9291 | ||
ed61bbc6 TC |
9292 | rebalance_domains(rq, CPU_IDLE); |
9293 | } | |
83cd4fe2 | 9294 | |
c5afb6a8 VG |
9295 | if (time_after(next_balance, rq->next_balance)) { |
9296 | next_balance = rq->next_balance; | |
9297 | update_next_balance = 1; | |
9298 | } | |
83cd4fe2 | 9299 | } |
c5afb6a8 VG |
9300 | |
9301 | /* | |
9302 | * next_balance will be updated only when there is a need. | |
9303 | * When the CPU is attached to null domain for ex, it will not be | |
9304 | * updated. | |
9305 | */ | |
9306 | if (likely(update_next_balance)) | |
9307 | nohz.next_balance = next_balance; | |
1c792db7 SS |
9308 | end: |
9309 | clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)); | |
83cd4fe2 VP |
9310 | } |
9311 | ||
9312 | /* | |
0b005cf5 | 9313 | * Current heuristic for kicking the idle load balancer in the presence |
1aaf90a4 | 9314 | * of an idle cpu in the system. |
0b005cf5 | 9315 | * - This rq has more than one task. |
1aaf90a4 VG |
9316 | * - This rq has at least one CFS task and the capacity of the CPU is |
9317 | * significantly reduced because of RT tasks or IRQs. | |
9318 | * - At parent of LLC scheduler domain level, this cpu's scheduler group has | |
9319 | * multiple busy cpu. | |
0b005cf5 SS |
9320 | * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler |
9321 | * domain span are idle. | |
83cd4fe2 | 9322 | */ |
1aaf90a4 | 9323 | static inline bool nohz_kick_needed(struct rq *rq) |
83cd4fe2 VP |
9324 | { |
9325 | unsigned long now = jiffies; | |
0e369d75 | 9326 | struct sched_domain_shared *sds; |
0b005cf5 | 9327 | struct sched_domain *sd; |
afe06efd | 9328 | int nr_busy, i, cpu = rq->cpu; |
1aaf90a4 | 9329 | bool kick = false; |
83cd4fe2 | 9330 | |
4a725627 | 9331 | if (unlikely(rq->idle_balance)) |
1aaf90a4 | 9332 | return false; |
83cd4fe2 | 9333 | |
1c792db7 SS |
9334 | /* |
9335 | * We may be recently in ticked or tickless idle mode. At the first | |
9336 | * busy tick after returning from idle, we will update the busy stats. | |
9337 | */ | |
69e1e811 | 9338 | set_cpu_sd_state_busy(); |
c1cc017c | 9339 | nohz_balance_exit_idle(cpu); |
0b005cf5 SS |
9340 | |
9341 | /* | |
9342 | * None are in tickless mode and hence no need for NOHZ idle load | |
9343 | * balancing. | |
9344 | */ | |
9345 | if (likely(!atomic_read(&nohz.nr_cpus))) | |
1aaf90a4 | 9346 | return false; |
1c792db7 SS |
9347 | |
9348 | if (time_before(now, nohz.next_balance)) | |
1aaf90a4 | 9349 | return false; |
83cd4fe2 | 9350 | |
0b005cf5 | 9351 | if (rq->nr_running >= 2) |
1aaf90a4 | 9352 | return true; |
83cd4fe2 | 9353 | |
067491b7 | 9354 | rcu_read_lock(); |
0e369d75 PZ |
9355 | sds = rcu_dereference(per_cpu(sd_llc_shared, cpu)); |
9356 | if (sds) { | |
9357 | /* | |
9358 | * XXX: write a coherent comment on why we do this. | |
9359 | * See also: http://lkml.kernel.org/r/20111202010832.602203411@sbsiddha-desk.sc.intel.com | |
9360 | */ | |
9361 | nr_busy = atomic_read(&sds->nr_busy_cpus); | |
1aaf90a4 VG |
9362 | if (nr_busy > 1) { |
9363 | kick = true; | |
9364 | goto unlock; | |
9365 | } | |
9366 | ||
83cd4fe2 | 9367 | } |
37dc6b50 | 9368 | |
1aaf90a4 VG |
9369 | sd = rcu_dereference(rq->sd); |
9370 | if (sd) { | |
9371 | if ((rq->cfs.h_nr_running >= 1) && | |
9372 | check_cpu_capacity(rq, sd)) { | |
9373 | kick = true; | |
9374 | goto unlock; | |
9375 | } | |
9376 | } | |
37dc6b50 | 9377 | |
1aaf90a4 | 9378 | sd = rcu_dereference(per_cpu(sd_asym, cpu)); |
afe06efd TC |
9379 | if (sd) { |
9380 | for_each_cpu(i, sched_domain_span(sd)) { | |
9381 | if (i == cpu || | |
9382 | !cpumask_test_cpu(i, nohz.idle_cpus_mask)) | |
9383 | continue; | |
067491b7 | 9384 | |
afe06efd TC |
9385 | if (sched_asym_prefer(i, cpu)) { |
9386 | kick = true; | |
9387 | goto unlock; | |
9388 | } | |
9389 | } | |
9390 | } | |
1aaf90a4 | 9391 | unlock: |
067491b7 | 9392 | rcu_read_unlock(); |
1aaf90a4 | 9393 | return kick; |
83cd4fe2 VP |
9394 | } |
9395 | #else | |
208cb16b | 9396 | static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { } |
83cd4fe2 VP |
9397 | #endif |
9398 | ||
9399 | /* | |
9400 | * run_rebalance_domains is triggered when needed from the scheduler tick. | |
9401 | * Also triggered for nohz idle balancing (with nohz_balancing_kick set). | |
9402 | */ | |
0766f788 | 9403 | static __latent_entropy void run_rebalance_domains(struct softirq_action *h) |
1e3c88bd | 9404 | { |
208cb16b | 9405 | struct rq *this_rq = this_rq(); |
6eb57e0d | 9406 | enum cpu_idle_type idle = this_rq->idle_balance ? |
1e3c88bd PZ |
9407 | CPU_IDLE : CPU_NOT_IDLE; |
9408 | ||
1e3c88bd | 9409 | /* |
83cd4fe2 | 9410 | * If this cpu has a pending nohz_balance_kick, then do the |
1e3c88bd | 9411 | * balancing on behalf of the other idle cpus whose ticks are |
d4573c3e PM |
9412 | * stopped. Do nohz_idle_balance *before* rebalance_domains to |
9413 | * give the idle cpus a chance to load balance. Else we may | |
9414 | * load balance only within the local sched_domain hierarchy | |
9415 | * and abort nohz_idle_balance altogether if we pull some load. | |
1e3c88bd | 9416 | */ |
208cb16b | 9417 | nohz_idle_balance(this_rq, idle); |
d4573c3e | 9418 | rebalance_domains(this_rq, idle); |
1e3c88bd PZ |
9419 | } |
9420 | ||
1e3c88bd PZ |
9421 | /* |
9422 | * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing. | |
1e3c88bd | 9423 | */ |
7caff66f | 9424 | void trigger_load_balance(struct rq *rq) |
1e3c88bd | 9425 | { |
1e3c88bd | 9426 | /* Don't need to rebalance while attached to NULL domain */ |
c726099e DL |
9427 | if (unlikely(on_null_domain(rq))) |
9428 | return; | |
9429 | ||
9430 | if (time_after_eq(jiffies, rq->next_balance)) | |
1e3c88bd | 9431 | raise_softirq(SCHED_SOFTIRQ); |
3451d024 | 9432 | #ifdef CONFIG_NO_HZ_COMMON |
c726099e | 9433 | if (nohz_kick_needed(rq)) |
0aeeeeba | 9434 | nohz_balancer_kick(); |
83cd4fe2 | 9435 | #endif |
1e3c88bd PZ |
9436 | } |
9437 | ||
0bcdcf28 CE |
9438 | static void rq_online_fair(struct rq *rq) |
9439 | { | |
9440 | update_sysctl(); | |
0e59bdae KT |
9441 | |
9442 | update_runtime_enabled(rq); | |
0bcdcf28 CE |
9443 | } |
9444 | ||
9445 | static void rq_offline_fair(struct rq *rq) | |
9446 | { | |
9447 | update_sysctl(); | |
a4c96ae3 PB |
9448 | |
9449 | /* Ensure any throttled groups are reachable by pick_next_task */ | |
9450 | unthrottle_offline_cfs_rqs(rq); | |
0bcdcf28 CE |
9451 | } |
9452 | ||
55e12e5e | 9453 | #endif /* CONFIG_SMP */ |
e1d1484f | 9454 | |
bf0f6f24 IM |
9455 | /* |
9456 | * scheduler tick hitting a task of our scheduling class: | |
9457 | */ | |
8f4d37ec | 9458 | static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) |
bf0f6f24 IM |
9459 | { |
9460 | struct cfs_rq *cfs_rq; | |
9461 | struct sched_entity *se = &curr->se; | |
9462 | ||
9463 | for_each_sched_entity(se) { | |
9464 | cfs_rq = cfs_rq_of(se); | |
8f4d37ec | 9465 | entity_tick(cfs_rq, se, queued); |
bf0f6f24 | 9466 | } |
18bf2805 | 9467 | |
b52da86e | 9468 | if (static_branch_unlikely(&sched_numa_balancing)) |
cbee9f88 | 9469 | task_tick_numa(rq, curr); |
bf0f6f24 IM |
9470 | } |
9471 | ||
9472 | /* | |
cd29fe6f PZ |
9473 | * called on fork with the child task as argument from the parent's context |
9474 | * - child not yet on the tasklist | |
9475 | * - preemption disabled | |
bf0f6f24 | 9476 | */ |
cd29fe6f | 9477 | static void task_fork_fair(struct task_struct *p) |
bf0f6f24 | 9478 | { |
4fc420c9 DN |
9479 | struct cfs_rq *cfs_rq; |
9480 | struct sched_entity *se = &p->se, *curr; | |
cd29fe6f | 9481 | struct rq *rq = this_rq(); |
8a8c69c3 | 9482 | struct rq_flags rf; |
bf0f6f24 | 9483 | |
8a8c69c3 | 9484 | rq_lock(rq, &rf); |
861d034e PZ |
9485 | update_rq_clock(rq); |
9486 | ||
4fc420c9 DN |
9487 | cfs_rq = task_cfs_rq(current); |
9488 | curr = cfs_rq->curr; | |
e210bffd PZ |
9489 | if (curr) { |
9490 | update_curr(cfs_rq); | |
b5d9d734 | 9491 | se->vruntime = curr->vruntime; |
e210bffd | 9492 | } |
aeb73b04 | 9493 | place_entity(cfs_rq, se, 1); |
4d78e7b6 | 9494 | |
cd29fe6f | 9495 | if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) { |
87fefa38 | 9496 | /* |
edcb60a3 IM |
9497 | * Upon rescheduling, sched_class::put_prev_task() will place |
9498 | * 'current' within the tree based on its new key value. | |
9499 | */ | |
4d78e7b6 | 9500 | swap(curr->vruntime, se->vruntime); |
8875125e | 9501 | resched_curr(rq); |
4d78e7b6 | 9502 | } |
bf0f6f24 | 9503 | |
88ec22d3 | 9504 | se->vruntime -= cfs_rq->min_vruntime; |
8a8c69c3 | 9505 | rq_unlock(rq, &rf); |
bf0f6f24 IM |
9506 | } |
9507 | ||
cb469845 SR |
9508 | /* |
9509 | * Priority of the task has changed. Check to see if we preempt | |
9510 | * the current task. | |
9511 | */ | |
da7a735e PZ |
9512 | static void |
9513 | prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio) | |
cb469845 | 9514 | { |
da0c1e65 | 9515 | if (!task_on_rq_queued(p)) |
da7a735e PZ |
9516 | return; |
9517 | ||
cb469845 SR |
9518 | /* |
9519 | * Reschedule if we are currently running on this runqueue and | |
9520 | * our priority decreased, or if we are not currently running on | |
9521 | * this runqueue and our priority is higher than the current's | |
9522 | */ | |
da7a735e | 9523 | if (rq->curr == p) { |
cb469845 | 9524 | if (p->prio > oldprio) |
8875125e | 9525 | resched_curr(rq); |
cb469845 | 9526 | } else |
15afe09b | 9527 | check_preempt_curr(rq, p, 0); |
cb469845 SR |
9528 | } |
9529 | ||
daa59407 | 9530 | static inline bool vruntime_normalized(struct task_struct *p) |
da7a735e PZ |
9531 | { |
9532 | struct sched_entity *se = &p->se; | |
da7a735e PZ |
9533 | |
9534 | /* | |
daa59407 BP |
9535 | * In both the TASK_ON_RQ_QUEUED and TASK_ON_RQ_MIGRATING cases, |
9536 | * the dequeue_entity(.flags=0) will already have normalized the | |
9537 | * vruntime. | |
9538 | */ | |
9539 | if (p->on_rq) | |
9540 | return true; | |
9541 | ||
9542 | /* | |
9543 | * When !on_rq, vruntime of the task has usually NOT been normalized. | |
9544 | * But there are some cases where it has already been normalized: | |
da7a735e | 9545 | * |
daa59407 BP |
9546 | * - A forked child which is waiting for being woken up by |
9547 | * wake_up_new_task(). | |
9548 | * - A task which has been woken up by try_to_wake_up() and | |
9549 | * waiting for actually being woken up by sched_ttwu_pending(). | |
da7a735e | 9550 | */ |
878b3587 SM |
9551 | if (!se->sum_exec_runtime || |
9552 | (p->state == TASK_WAKING && p->sched_remote_wakeup)) | |
daa59407 BP |
9553 | return true; |
9554 | ||
9555 | return false; | |
9556 | } | |
9557 | ||
09a43ace VG |
9558 | #ifdef CONFIG_FAIR_GROUP_SCHED |
9559 | /* | |
9560 | * Propagate the changes of the sched_entity across the tg tree to make it | |
9561 | * visible to the root | |
9562 | */ | |
9563 | static void propagate_entity_cfs_rq(struct sched_entity *se) | |
9564 | { | |
9565 | struct cfs_rq *cfs_rq; | |
9566 | ||
9567 | /* Start to propagate at parent */ | |
9568 | se = se->parent; | |
9569 | ||
9570 | for_each_sched_entity(se) { | |
9571 | cfs_rq = cfs_rq_of(se); | |
9572 | ||
9573 | if (cfs_rq_throttled(cfs_rq)) | |
9574 | break; | |
9575 | ||
88c0616e | 9576 | update_load_avg(cfs_rq, se, UPDATE_TG); |
09a43ace VG |
9577 | } |
9578 | } | |
9579 | #else | |
9580 | static void propagate_entity_cfs_rq(struct sched_entity *se) { } | |
9581 | #endif | |
9582 | ||
df217913 | 9583 | static void detach_entity_cfs_rq(struct sched_entity *se) |
daa59407 | 9584 | { |
daa59407 BP |
9585 | struct cfs_rq *cfs_rq = cfs_rq_of(se); |
9586 | ||
9d89c257 | 9587 | /* Catch up with the cfs_rq and remove our load when we leave */ |
88c0616e | 9588 | update_load_avg(cfs_rq, se, 0); |
a05e8c51 | 9589 | detach_entity_load_avg(cfs_rq, se); |
7c3edd2c | 9590 | update_tg_load_avg(cfs_rq, false); |
09a43ace | 9591 | propagate_entity_cfs_rq(se); |
da7a735e PZ |
9592 | } |
9593 | ||
df217913 | 9594 | static void attach_entity_cfs_rq(struct sched_entity *se) |
cb469845 | 9595 | { |
daa59407 | 9596 | struct cfs_rq *cfs_rq = cfs_rq_of(se); |
7855a35a BP |
9597 | |
9598 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
eb7a59b2 M |
9599 | /* |
9600 | * Since the real-depth could have been changed (only FAIR | |
9601 | * class maintain depth value), reset depth properly. | |
9602 | */ | |
9603 | se->depth = se->parent ? se->parent->depth + 1 : 0; | |
9604 | #endif | |
7855a35a | 9605 | |
df217913 | 9606 | /* Synchronize entity with its cfs_rq */ |
88c0616e | 9607 | update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD); |
daa59407 | 9608 | attach_entity_load_avg(cfs_rq, se); |
7c3edd2c | 9609 | update_tg_load_avg(cfs_rq, false); |
09a43ace | 9610 | propagate_entity_cfs_rq(se); |
df217913 VG |
9611 | } |
9612 | ||
9613 | static void detach_task_cfs_rq(struct task_struct *p) | |
9614 | { | |
9615 | struct sched_entity *se = &p->se; | |
9616 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
9617 | ||
9618 | if (!vruntime_normalized(p)) { | |
9619 | /* | |
9620 | * Fix up our vruntime so that the current sleep doesn't | |
9621 | * cause 'unlimited' sleep bonus. | |
9622 | */ | |
9623 | place_entity(cfs_rq, se, 0); | |
9624 | se->vruntime -= cfs_rq->min_vruntime; | |
9625 | } | |
9626 | ||
9627 | detach_entity_cfs_rq(se); | |
9628 | } | |
9629 | ||
9630 | static void attach_task_cfs_rq(struct task_struct *p) | |
9631 | { | |
9632 | struct sched_entity *se = &p->se; | |
9633 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
9634 | ||
9635 | attach_entity_cfs_rq(se); | |
daa59407 BP |
9636 | |
9637 | if (!vruntime_normalized(p)) | |
9638 | se->vruntime += cfs_rq->min_vruntime; | |
9639 | } | |
6efdb105 | 9640 | |
daa59407 BP |
9641 | static void switched_from_fair(struct rq *rq, struct task_struct *p) |
9642 | { | |
9643 | detach_task_cfs_rq(p); | |
9644 | } | |
9645 | ||
9646 | static void switched_to_fair(struct rq *rq, struct task_struct *p) | |
9647 | { | |
9648 | attach_task_cfs_rq(p); | |
7855a35a | 9649 | |
daa59407 | 9650 | if (task_on_rq_queued(p)) { |
7855a35a | 9651 | /* |
daa59407 BP |
9652 | * We were most likely switched from sched_rt, so |
9653 | * kick off the schedule if running, otherwise just see | |
9654 | * if we can still preempt the current task. | |
7855a35a | 9655 | */ |
daa59407 BP |
9656 | if (rq->curr == p) |
9657 | resched_curr(rq); | |
9658 | else | |
9659 | check_preempt_curr(rq, p, 0); | |
7855a35a | 9660 | } |
cb469845 SR |
9661 | } |
9662 | ||
83b699ed SV |
9663 | /* Account for a task changing its policy or group. |
9664 | * | |
9665 | * This routine is mostly called to set cfs_rq->curr field when a task | |
9666 | * migrates between groups/classes. | |
9667 | */ | |
9668 | static void set_curr_task_fair(struct rq *rq) | |
9669 | { | |
9670 | struct sched_entity *se = &rq->curr->se; | |
9671 | ||
ec12cb7f PT |
9672 | for_each_sched_entity(se) { |
9673 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
9674 | ||
9675 | set_next_entity(cfs_rq, se); | |
9676 | /* ensure bandwidth has been allocated on our new cfs_rq */ | |
9677 | account_cfs_rq_runtime(cfs_rq, 0); | |
9678 | } | |
83b699ed SV |
9679 | } |
9680 | ||
029632fb PZ |
9681 | void init_cfs_rq(struct cfs_rq *cfs_rq) |
9682 | { | |
bfb06889 | 9683 | cfs_rq->tasks_timeline = RB_ROOT_CACHED; |
029632fb PZ |
9684 | cfs_rq->min_vruntime = (u64)(-(1LL << 20)); |
9685 | #ifndef CONFIG_64BIT | |
9686 | cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; | |
9687 | #endif | |
141965c7 | 9688 | #ifdef CONFIG_SMP |
2a2f5d4e | 9689 | raw_spin_lock_init(&cfs_rq->removed.lock); |
9ee474f5 | 9690 | #endif |
029632fb PZ |
9691 | } |
9692 | ||
810b3817 | 9693 | #ifdef CONFIG_FAIR_GROUP_SCHED |
ea86cb4b VG |
9694 | static void task_set_group_fair(struct task_struct *p) |
9695 | { | |
9696 | struct sched_entity *se = &p->se; | |
9697 | ||
9698 | set_task_rq(p, task_cpu(p)); | |
9699 | se->depth = se->parent ? se->parent->depth + 1 : 0; | |
9700 | } | |
9701 | ||
bc54da21 | 9702 | static void task_move_group_fair(struct task_struct *p) |
810b3817 | 9703 | { |
daa59407 | 9704 | detach_task_cfs_rq(p); |
b2b5ce02 | 9705 | set_task_rq(p, task_cpu(p)); |
6efdb105 BP |
9706 | |
9707 | #ifdef CONFIG_SMP | |
9708 | /* Tell se's cfs_rq has been changed -- migrated */ | |
9709 | p->se.avg.last_update_time = 0; | |
9710 | #endif | |
daa59407 | 9711 | attach_task_cfs_rq(p); |
810b3817 | 9712 | } |
029632fb | 9713 | |
ea86cb4b VG |
9714 | static void task_change_group_fair(struct task_struct *p, int type) |
9715 | { | |
9716 | switch (type) { | |
9717 | case TASK_SET_GROUP: | |
9718 | task_set_group_fair(p); | |
9719 | break; | |
9720 | ||
9721 | case TASK_MOVE_GROUP: | |
9722 | task_move_group_fair(p); | |
9723 | break; | |
9724 | } | |
9725 | } | |
9726 | ||
029632fb PZ |
9727 | void free_fair_sched_group(struct task_group *tg) |
9728 | { | |
9729 | int i; | |
9730 | ||
9731 | destroy_cfs_bandwidth(tg_cfs_bandwidth(tg)); | |
9732 | ||
9733 | for_each_possible_cpu(i) { | |
9734 | if (tg->cfs_rq) | |
9735 | kfree(tg->cfs_rq[i]); | |
6fe1f348 | 9736 | if (tg->se) |
029632fb PZ |
9737 | kfree(tg->se[i]); |
9738 | } | |
9739 | ||
9740 | kfree(tg->cfs_rq); | |
9741 | kfree(tg->se); | |
9742 | } | |
9743 | ||
9744 | int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) | |
9745 | { | |
029632fb | 9746 | struct sched_entity *se; |
b7fa30c9 | 9747 | struct cfs_rq *cfs_rq; |
029632fb PZ |
9748 | int i; |
9749 | ||
9750 | tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL); | |
9751 | if (!tg->cfs_rq) | |
9752 | goto err; | |
9753 | tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL); | |
9754 | if (!tg->se) | |
9755 | goto err; | |
9756 | ||
9757 | tg->shares = NICE_0_LOAD; | |
9758 | ||
9759 | init_cfs_bandwidth(tg_cfs_bandwidth(tg)); | |
9760 | ||
9761 | for_each_possible_cpu(i) { | |
9762 | cfs_rq = kzalloc_node(sizeof(struct cfs_rq), | |
9763 | GFP_KERNEL, cpu_to_node(i)); | |
9764 | if (!cfs_rq) | |
9765 | goto err; | |
9766 | ||
9767 | se = kzalloc_node(sizeof(struct sched_entity), | |
9768 | GFP_KERNEL, cpu_to_node(i)); | |
9769 | if (!se) | |
9770 | goto err_free_rq; | |
9771 | ||
9772 | init_cfs_rq(cfs_rq); | |
9773 | init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]); | |
540247fb | 9774 | init_entity_runnable_average(se); |
029632fb PZ |
9775 | } |
9776 | ||
9777 | return 1; | |
9778 | ||
9779 | err_free_rq: | |
9780 | kfree(cfs_rq); | |
9781 | err: | |
9782 | return 0; | |
9783 | } | |
9784 | ||
8663e24d PZ |
9785 | void online_fair_sched_group(struct task_group *tg) |
9786 | { | |
9787 | struct sched_entity *se; | |
a7396a6c | 9788 | struct rq_flags rf; |
8663e24d PZ |
9789 | struct rq *rq; |
9790 | int i; | |
9791 | ||
9792 | for_each_possible_cpu(i) { | |
9793 | rq = cpu_rq(i); | |
9794 | se = tg->se[i]; | |
a7396a6c | 9795 | rq_lock_irq(rq, &rf); |
4126bad6 | 9796 | update_rq_clock(rq); |
d0326691 | 9797 | attach_entity_cfs_rq(se); |
55e16d30 | 9798 | sync_throttle(tg, i); |
a7396a6c | 9799 | rq_unlock_irq(rq, &rf); |
8663e24d PZ |
9800 | } |
9801 | } | |
9802 | ||
6fe1f348 | 9803 | void unregister_fair_sched_group(struct task_group *tg) |
029632fb | 9804 | { |
029632fb | 9805 | unsigned long flags; |
6fe1f348 PZ |
9806 | struct rq *rq; |
9807 | int cpu; | |
029632fb | 9808 | |
6fe1f348 PZ |
9809 | for_each_possible_cpu(cpu) { |
9810 | if (tg->se[cpu]) | |
9811 | remove_entity_load_avg(tg->se[cpu]); | |
029632fb | 9812 | |
6fe1f348 PZ |
9813 | /* |
9814 | * Only empty task groups can be destroyed; so we can speculatively | |
9815 | * check on_list without danger of it being re-added. | |
9816 | */ | |
9817 | if (!tg->cfs_rq[cpu]->on_list) | |
9818 | continue; | |
9819 | ||
9820 | rq = cpu_rq(cpu); | |
9821 | ||
9822 | raw_spin_lock_irqsave(&rq->lock, flags); | |
9823 | list_del_leaf_cfs_rq(tg->cfs_rq[cpu]); | |
9824 | raw_spin_unlock_irqrestore(&rq->lock, flags); | |
9825 | } | |
029632fb PZ |
9826 | } |
9827 | ||
9828 | void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, | |
9829 | struct sched_entity *se, int cpu, | |
9830 | struct sched_entity *parent) | |
9831 | { | |
9832 | struct rq *rq = cpu_rq(cpu); | |
9833 | ||
9834 | cfs_rq->tg = tg; | |
9835 | cfs_rq->rq = rq; | |
029632fb PZ |
9836 | init_cfs_rq_runtime(cfs_rq); |
9837 | ||
9838 | tg->cfs_rq[cpu] = cfs_rq; | |
9839 | tg->se[cpu] = se; | |
9840 | ||
9841 | /* se could be NULL for root_task_group */ | |
9842 | if (!se) | |
9843 | return; | |
9844 | ||
fed14d45 | 9845 | if (!parent) { |
029632fb | 9846 | se->cfs_rq = &rq->cfs; |
fed14d45 PZ |
9847 | se->depth = 0; |
9848 | } else { | |
029632fb | 9849 | se->cfs_rq = parent->my_q; |
fed14d45 PZ |
9850 | se->depth = parent->depth + 1; |
9851 | } | |
029632fb PZ |
9852 | |
9853 | se->my_q = cfs_rq; | |
0ac9b1c2 PT |
9854 | /* guarantee group entities always have weight */ |
9855 | update_load_set(&se->load, NICE_0_LOAD); | |
029632fb PZ |
9856 | se->parent = parent; |
9857 | } | |
9858 | ||
9859 | static DEFINE_MUTEX(shares_mutex); | |
9860 | ||
9861 | int sched_group_set_shares(struct task_group *tg, unsigned long shares) | |
9862 | { | |
9863 | int i; | |
029632fb PZ |
9864 | |
9865 | /* | |
9866 | * We can't change the weight of the root cgroup. | |
9867 | */ | |
9868 | if (!tg->se[0]) | |
9869 | return -EINVAL; | |
9870 | ||
9871 | shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES)); | |
9872 | ||
9873 | mutex_lock(&shares_mutex); | |
9874 | if (tg->shares == shares) | |
9875 | goto done; | |
9876 | ||
9877 | tg->shares = shares; | |
9878 | for_each_possible_cpu(i) { | |
9879 | struct rq *rq = cpu_rq(i); | |
8a8c69c3 PZ |
9880 | struct sched_entity *se = tg->se[i]; |
9881 | struct rq_flags rf; | |
029632fb | 9882 | |
029632fb | 9883 | /* Propagate contribution to hierarchy */ |
8a8c69c3 | 9884 | rq_lock_irqsave(rq, &rf); |
71b1da46 | 9885 | update_rq_clock(rq); |
89ee048f | 9886 | for_each_sched_entity(se) { |
88c0616e | 9887 | update_load_avg(cfs_rq_of(se), se, UPDATE_TG); |
1ea6c46a | 9888 | update_cfs_group(se); |
89ee048f | 9889 | } |
8a8c69c3 | 9890 | rq_unlock_irqrestore(rq, &rf); |
029632fb PZ |
9891 | } |
9892 | ||
9893 | done: | |
9894 | mutex_unlock(&shares_mutex); | |
9895 | return 0; | |
9896 | } | |
9897 | #else /* CONFIG_FAIR_GROUP_SCHED */ | |
9898 | ||
9899 | void free_fair_sched_group(struct task_group *tg) { } | |
9900 | ||
9901 | int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) | |
9902 | { | |
9903 | return 1; | |
9904 | } | |
9905 | ||
8663e24d PZ |
9906 | void online_fair_sched_group(struct task_group *tg) { } |
9907 | ||
6fe1f348 | 9908 | void unregister_fair_sched_group(struct task_group *tg) { } |
029632fb PZ |
9909 | |
9910 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
9911 | ||
810b3817 | 9912 | |
6d686f45 | 9913 | static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task) |
0d721cea PW |
9914 | { |
9915 | struct sched_entity *se = &task->se; | |
0d721cea PW |
9916 | unsigned int rr_interval = 0; |
9917 | ||
9918 | /* | |
9919 | * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise | |
9920 | * idle runqueue: | |
9921 | */ | |
0d721cea | 9922 | if (rq->cfs.load.weight) |
a59f4e07 | 9923 | rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se)); |
0d721cea PW |
9924 | |
9925 | return rr_interval; | |
9926 | } | |
9927 | ||
bf0f6f24 IM |
9928 | /* |
9929 | * All the scheduling class methods: | |
9930 | */ | |
029632fb | 9931 | const struct sched_class fair_sched_class = { |
5522d5d5 | 9932 | .next = &idle_sched_class, |
bf0f6f24 IM |
9933 | .enqueue_task = enqueue_task_fair, |
9934 | .dequeue_task = dequeue_task_fair, | |
9935 | .yield_task = yield_task_fair, | |
d95f4122 | 9936 | .yield_to_task = yield_to_task_fair, |
bf0f6f24 | 9937 | |
2e09bf55 | 9938 | .check_preempt_curr = check_preempt_wakeup, |
bf0f6f24 IM |
9939 | |
9940 | .pick_next_task = pick_next_task_fair, | |
9941 | .put_prev_task = put_prev_task_fair, | |
9942 | ||
681f3e68 | 9943 | #ifdef CONFIG_SMP |
4ce72a2c | 9944 | .select_task_rq = select_task_rq_fair, |
0a74bef8 | 9945 | .migrate_task_rq = migrate_task_rq_fair, |
141965c7 | 9946 | |
0bcdcf28 CE |
9947 | .rq_online = rq_online_fair, |
9948 | .rq_offline = rq_offline_fair, | |
88ec22d3 | 9949 | |
12695578 | 9950 | .task_dead = task_dead_fair, |
c5b28038 | 9951 | .set_cpus_allowed = set_cpus_allowed_common, |
681f3e68 | 9952 | #endif |
bf0f6f24 | 9953 | |
83b699ed | 9954 | .set_curr_task = set_curr_task_fair, |
bf0f6f24 | 9955 | .task_tick = task_tick_fair, |
cd29fe6f | 9956 | .task_fork = task_fork_fair, |
cb469845 SR |
9957 | |
9958 | .prio_changed = prio_changed_fair, | |
da7a735e | 9959 | .switched_from = switched_from_fair, |
cb469845 | 9960 | .switched_to = switched_to_fair, |
810b3817 | 9961 | |
0d721cea PW |
9962 | .get_rr_interval = get_rr_interval_fair, |
9963 | ||
6e998916 SG |
9964 | .update_curr = update_curr_fair, |
9965 | ||
810b3817 | 9966 | #ifdef CONFIG_FAIR_GROUP_SCHED |
ea86cb4b | 9967 | .task_change_group = task_change_group_fair, |
810b3817 | 9968 | #endif |
bf0f6f24 IM |
9969 | }; |
9970 | ||
9971 | #ifdef CONFIG_SCHED_DEBUG | |
029632fb | 9972 | void print_cfs_stats(struct seq_file *m, int cpu) |
bf0f6f24 | 9973 | { |
cf740dd8 | 9974 | struct cfs_rq *cfs_rq; |
bf0f6f24 | 9975 | |
5973e5b9 | 9976 | rcu_read_lock(); |
cf740dd8 | 9977 | for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) |
5cef9eca | 9978 | print_cfs_rq(m, cpu, cfs_rq); |
5973e5b9 | 9979 | rcu_read_unlock(); |
bf0f6f24 | 9980 | } |
397f2378 SD |
9981 | |
9982 | #ifdef CONFIG_NUMA_BALANCING | |
9983 | void show_numa_stats(struct task_struct *p, struct seq_file *m) | |
9984 | { | |
9985 | int node; | |
9986 | unsigned long tsf = 0, tpf = 0, gsf = 0, gpf = 0; | |
9987 | ||
9988 | for_each_online_node(node) { | |
9989 | if (p->numa_faults) { | |
9990 | tsf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 0)]; | |
9991 | tpf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 1)]; | |
9992 | } | |
9993 | if (p->numa_group) { | |
9994 | gsf = p->numa_group->faults[task_faults_idx(NUMA_MEM, node, 0)], | |
9995 | gpf = p->numa_group->faults[task_faults_idx(NUMA_MEM, node, 1)]; | |
9996 | } | |
9997 | print_numa_stats(m, node, tsf, tpf, gsf, gpf); | |
9998 | } | |
9999 | } | |
10000 | #endif /* CONFIG_NUMA_BALANCING */ | |
10001 | #endif /* CONFIG_SCHED_DEBUG */ | |
029632fb PZ |
10002 | |
10003 | __init void init_sched_fair_class(void) | |
10004 | { | |
10005 | #ifdef CONFIG_SMP | |
10006 | open_softirq(SCHED_SOFTIRQ, run_rebalance_domains); | |
10007 | ||
3451d024 | 10008 | #ifdef CONFIG_NO_HZ_COMMON |
554cecaf | 10009 | nohz.next_balance = jiffies; |
029632fb | 10010 | zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); |
029632fb PZ |
10011 | #endif |
10012 | #endif /* SMP */ | |
10013 | ||
10014 | } |