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bf0f6f24 IM |
1 | /* |
2 | * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH) | |
3 | * | |
4 | * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
5 | * | |
6 | * Interactivity improvements by Mike Galbraith | |
7 | * (C) 2007 Mike Galbraith <efault@gmx.de> | |
8 | * | |
9 | * Various enhancements by Dmitry Adamushko. | |
10 | * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com> | |
11 | * | |
12 | * Group scheduling enhancements by Srivatsa Vaddagiri | |
13 | * Copyright IBM Corporation, 2007 | |
14 | * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> | |
15 | * | |
16 | * Scaled math optimizations by Thomas Gleixner | |
17 | * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de> | |
21805085 PZ |
18 | * |
19 | * Adaptive scheduling granularity, math enhancements by Peter Zijlstra | |
20 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> | |
bf0f6f24 IM |
21 | */ |
22 | ||
9745512c | 23 | #include <linux/latencytop.h> |
1983a922 | 24 | #include <linux/sched.h> |
3436ae12 | 25 | #include <linux/cpumask.h> |
83a0a96a | 26 | #include <linux/cpuidle.h> |
029632fb PZ |
27 | #include <linux/slab.h> |
28 | #include <linux/profile.h> | |
29 | #include <linux/interrupt.h> | |
cbee9f88 | 30 | #include <linux/mempolicy.h> |
e14808b4 | 31 | #include <linux/migrate.h> |
cbee9f88 | 32 | #include <linux/task_work.h> |
029632fb PZ |
33 | |
34 | #include <trace/events/sched.h> | |
35 | ||
36 | #include "sched.h" | |
9745512c | 37 | |
bf0f6f24 | 38 | /* |
21805085 | 39 | * Targeted preemption latency for CPU-bound tasks: |
864616ee | 40 | * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds) |
bf0f6f24 | 41 | * |
21805085 | 42 | * NOTE: this latency value is not the same as the concept of |
d274a4ce IM |
43 | * 'timeslice length' - timeslices in CFS are of variable length |
44 | * and have no persistent notion like in traditional, time-slice | |
45 | * based scheduling concepts. | |
bf0f6f24 | 46 | * |
d274a4ce IM |
47 | * (to see the precise effective timeslice length of your workload, |
48 | * run vmstat and monitor the context-switches (cs) field) | |
bf0f6f24 | 49 | */ |
21406928 MG |
50 | unsigned int sysctl_sched_latency = 6000000ULL; |
51 | unsigned int normalized_sysctl_sched_latency = 6000000ULL; | |
2bd8e6d4 | 52 | |
1983a922 CE |
53 | /* |
54 | * The initial- and re-scaling of tunables is configurable | |
55 | * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus)) | |
56 | * | |
57 | * Options are: | |
58 | * SCHED_TUNABLESCALING_NONE - unscaled, always *1 | |
59 | * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus) | |
60 | * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus | |
61 | */ | |
62 | enum sched_tunable_scaling sysctl_sched_tunable_scaling | |
63 | = SCHED_TUNABLESCALING_LOG; | |
64 | ||
2bd8e6d4 | 65 | /* |
b2be5e96 | 66 | * Minimal preemption granularity for CPU-bound tasks: |
864616ee | 67 | * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds) |
2bd8e6d4 | 68 | */ |
0bf377bb IM |
69 | unsigned int sysctl_sched_min_granularity = 750000ULL; |
70 | unsigned int normalized_sysctl_sched_min_granularity = 750000ULL; | |
21805085 PZ |
71 | |
72 | /* | |
b2be5e96 PZ |
73 | * is kept at sysctl_sched_latency / sysctl_sched_min_granularity |
74 | */ | |
0bf377bb | 75 | static unsigned int sched_nr_latency = 8; |
b2be5e96 PZ |
76 | |
77 | /* | |
2bba22c5 | 78 | * After fork, child runs first. If set to 0 (default) then |
b2be5e96 | 79 | * parent will (try to) run first. |
21805085 | 80 | */ |
2bba22c5 | 81 | unsigned int sysctl_sched_child_runs_first __read_mostly; |
bf0f6f24 | 82 | |
bf0f6f24 IM |
83 | /* |
84 | * SCHED_OTHER wake-up granularity. | |
172e082a | 85 | * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds) |
bf0f6f24 IM |
86 | * |
87 | * This option delays the preemption effects of decoupled workloads | |
88 | * and reduces their over-scheduling. Synchronous workloads will still | |
89 | * have immediate wakeup/sleep latencies. | |
90 | */ | |
172e082a | 91 | unsigned int sysctl_sched_wakeup_granularity = 1000000UL; |
0bcdcf28 | 92 | unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL; |
bf0f6f24 | 93 | |
da84d961 IM |
94 | const_debug unsigned int sysctl_sched_migration_cost = 500000UL; |
95 | ||
a7a4f8a7 PT |
96 | /* |
97 | * The exponential sliding window over which load is averaged for shares | |
98 | * distribution. | |
99 | * (default: 10msec) | |
100 | */ | |
101 | unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL; | |
102 | ||
ec12cb7f PT |
103 | #ifdef CONFIG_CFS_BANDWIDTH |
104 | /* | |
105 | * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool | |
106 | * each time a cfs_rq requests quota. | |
107 | * | |
108 | * Note: in the case that the slice exceeds the runtime remaining (either due | |
109 | * to consumption or the quota being specified to be smaller than the slice) | |
110 | * we will always only issue the remaining available time. | |
111 | * | |
112 | * default: 5 msec, units: microseconds | |
113 | */ | |
114 | unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL; | |
115 | #endif | |
116 | ||
8527632d PG |
117 | static inline void update_load_add(struct load_weight *lw, unsigned long inc) |
118 | { | |
119 | lw->weight += inc; | |
120 | lw->inv_weight = 0; | |
121 | } | |
122 | ||
123 | static inline void update_load_sub(struct load_weight *lw, unsigned long dec) | |
124 | { | |
125 | lw->weight -= dec; | |
126 | lw->inv_weight = 0; | |
127 | } | |
128 | ||
129 | static inline void update_load_set(struct load_weight *lw, unsigned long w) | |
130 | { | |
131 | lw->weight = w; | |
132 | lw->inv_weight = 0; | |
133 | } | |
134 | ||
029632fb PZ |
135 | /* |
136 | * Increase the granularity value when there are more CPUs, | |
137 | * because with more CPUs the 'effective latency' as visible | |
138 | * to users decreases. But the relationship is not linear, | |
139 | * so pick a second-best guess by going with the log2 of the | |
140 | * number of CPUs. | |
141 | * | |
142 | * This idea comes from the SD scheduler of Con Kolivas: | |
143 | */ | |
144 | static int get_update_sysctl_factor(void) | |
145 | { | |
146 | unsigned int cpus = min_t(int, num_online_cpus(), 8); | |
147 | unsigned int factor; | |
148 | ||
149 | switch (sysctl_sched_tunable_scaling) { | |
150 | case SCHED_TUNABLESCALING_NONE: | |
151 | factor = 1; | |
152 | break; | |
153 | case SCHED_TUNABLESCALING_LINEAR: | |
154 | factor = cpus; | |
155 | break; | |
156 | case SCHED_TUNABLESCALING_LOG: | |
157 | default: | |
158 | factor = 1 + ilog2(cpus); | |
159 | break; | |
160 | } | |
161 | ||
162 | return factor; | |
163 | } | |
164 | ||
165 | static void update_sysctl(void) | |
166 | { | |
167 | unsigned int factor = get_update_sysctl_factor(); | |
168 | ||
169 | #define SET_SYSCTL(name) \ | |
170 | (sysctl_##name = (factor) * normalized_sysctl_##name) | |
171 | SET_SYSCTL(sched_min_granularity); | |
172 | SET_SYSCTL(sched_latency); | |
173 | SET_SYSCTL(sched_wakeup_granularity); | |
174 | #undef SET_SYSCTL | |
175 | } | |
176 | ||
177 | void sched_init_granularity(void) | |
178 | { | |
179 | update_sysctl(); | |
180 | } | |
181 | ||
9dbdb155 | 182 | #define WMULT_CONST (~0U) |
029632fb PZ |
183 | #define WMULT_SHIFT 32 |
184 | ||
9dbdb155 PZ |
185 | static void __update_inv_weight(struct load_weight *lw) |
186 | { | |
187 | unsigned long w; | |
188 | ||
189 | if (likely(lw->inv_weight)) | |
190 | return; | |
191 | ||
192 | w = scale_load_down(lw->weight); | |
193 | ||
194 | if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST)) | |
195 | lw->inv_weight = 1; | |
196 | else if (unlikely(!w)) | |
197 | lw->inv_weight = WMULT_CONST; | |
198 | else | |
199 | lw->inv_weight = WMULT_CONST / w; | |
200 | } | |
029632fb PZ |
201 | |
202 | /* | |
9dbdb155 PZ |
203 | * delta_exec * weight / lw.weight |
204 | * OR | |
205 | * (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT | |
206 | * | |
207 | * Either weight := NICE_0_LOAD and lw \e prio_to_wmult[], in which case | |
208 | * we're guaranteed shift stays positive because inv_weight is guaranteed to | |
209 | * fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22. | |
210 | * | |
211 | * Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus | |
212 | * weight/lw.weight <= 1, and therefore our shift will also be positive. | |
029632fb | 213 | */ |
9dbdb155 | 214 | static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight *lw) |
029632fb | 215 | { |
9dbdb155 PZ |
216 | u64 fact = scale_load_down(weight); |
217 | int shift = WMULT_SHIFT; | |
029632fb | 218 | |
9dbdb155 | 219 | __update_inv_weight(lw); |
029632fb | 220 | |
9dbdb155 PZ |
221 | if (unlikely(fact >> 32)) { |
222 | while (fact >> 32) { | |
223 | fact >>= 1; | |
224 | shift--; | |
225 | } | |
029632fb PZ |
226 | } |
227 | ||
9dbdb155 PZ |
228 | /* hint to use a 32x32->64 mul */ |
229 | fact = (u64)(u32)fact * lw->inv_weight; | |
029632fb | 230 | |
9dbdb155 PZ |
231 | while (fact >> 32) { |
232 | fact >>= 1; | |
233 | shift--; | |
234 | } | |
029632fb | 235 | |
9dbdb155 | 236 | return mul_u64_u32_shr(delta_exec, fact, shift); |
029632fb PZ |
237 | } |
238 | ||
239 | ||
240 | const struct sched_class fair_sched_class; | |
a4c2f00f | 241 | |
bf0f6f24 IM |
242 | /************************************************************** |
243 | * CFS operations on generic schedulable entities: | |
244 | */ | |
245 | ||
62160e3f | 246 | #ifdef CONFIG_FAIR_GROUP_SCHED |
bf0f6f24 | 247 | |
62160e3f | 248 | /* cpu runqueue to which this cfs_rq is attached */ |
bf0f6f24 IM |
249 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
250 | { | |
62160e3f | 251 | return cfs_rq->rq; |
bf0f6f24 IM |
252 | } |
253 | ||
62160e3f IM |
254 | /* An entity is a task if it doesn't "own" a runqueue */ |
255 | #define entity_is_task(se) (!se->my_q) | |
bf0f6f24 | 256 | |
8f48894f PZ |
257 | static inline struct task_struct *task_of(struct sched_entity *se) |
258 | { | |
259 | #ifdef CONFIG_SCHED_DEBUG | |
260 | WARN_ON_ONCE(!entity_is_task(se)); | |
261 | #endif | |
262 | return container_of(se, struct task_struct, se); | |
263 | } | |
264 | ||
b758149c PZ |
265 | /* Walk up scheduling entities hierarchy */ |
266 | #define for_each_sched_entity(se) \ | |
267 | for (; se; se = se->parent) | |
268 | ||
269 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) | |
270 | { | |
271 | return p->se.cfs_rq; | |
272 | } | |
273 | ||
274 | /* runqueue on which this entity is (to be) queued */ | |
275 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) | |
276 | { | |
277 | return se->cfs_rq; | |
278 | } | |
279 | ||
280 | /* runqueue "owned" by this group */ | |
281 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
282 | { | |
283 | return grp->my_q; | |
284 | } | |
285 | ||
aff3e498 PT |
286 | static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, |
287 | int force_update); | |
9ee474f5 | 288 | |
3d4b47b4 PZ |
289 | static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
290 | { | |
291 | if (!cfs_rq->on_list) { | |
67e86250 PT |
292 | /* |
293 | * Ensure we either appear before our parent (if already | |
294 | * enqueued) or force our parent to appear after us when it is | |
295 | * enqueued. The fact that we always enqueue bottom-up | |
296 | * reduces this to two cases. | |
297 | */ | |
298 | if (cfs_rq->tg->parent && | |
299 | cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) { | |
300 | list_add_rcu(&cfs_rq->leaf_cfs_rq_list, | |
301 | &rq_of(cfs_rq)->leaf_cfs_rq_list); | |
302 | } else { | |
303 | list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list, | |
3d4b47b4 | 304 | &rq_of(cfs_rq)->leaf_cfs_rq_list); |
67e86250 | 305 | } |
3d4b47b4 PZ |
306 | |
307 | cfs_rq->on_list = 1; | |
9ee474f5 | 308 | /* We should have no load, but we need to update last_decay. */ |
aff3e498 | 309 | update_cfs_rq_blocked_load(cfs_rq, 0); |
3d4b47b4 PZ |
310 | } |
311 | } | |
312 | ||
313 | static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) | |
314 | { | |
315 | if (cfs_rq->on_list) { | |
316 | list_del_rcu(&cfs_rq->leaf_cfs_rq_list); | |
317 | cfs_rq->on_list = 0; | |
318 | } | |
319 | } | |
320 | ||
b758149c PZ |
321 | /* Iterate thr' all leaf cfs_rq's on a runqueue */ |
322 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ | |
323 | list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) | |
324 | ||
325 | /* Do the two (enqueued) entities belong to the same group ? */ | |
fed14d45 | 326 | static inline struct cfs_rq * |
b758149c PZ |
327 | is_same_group(struct sched_entity *se, struct sched_entity *pse) |
328 | { | |
329 | if (se->cfs_rq == pse->cfs_rq) | |
fed14d45 | 330 | return se->cfs_rq; |
b758149c | 331 | |
fed14d45 | 332 | return NULL; |
b758149c PZ |
333 | } |
334 | ||
335 | static inline struct sched_entity *parent_entity(struct sched_entity *se) | |
336 | { | |
337 | return se->parent; | |
338 | } | |
339 | ||
464b7527 PZ |
340 | static void |
341 | find_matching_se(struct sched_entity **se, struct sched_entity **pse) | |
342 | { | |
343 | int se_depth, pse_depth; | |
344 | ||
345 | /* | |
346 | * preemption test can be made between sibling entities who are in the | |
347 | * same cfs_rq i.e who have a common parent. Walk up the hierarchy of | |
348 | * both tasks until we find their ancestors who are siblings of common | |
349 | * parent. | |
350 | */ | |
351 | ||
352 | /* First walk up until both entities are at same depth */ | |
fed14d45 PZ |
353 | se_depth = (*se)->depth; |
354 | pse_depth = (*pse)->depth; | |
464b7527 PZ |
355 | |
356 | while (se_depth > pse_depth) { | |
357 | se_depth--; | |
358 | *se = parent_entity(*se); | |
359 | } | |
360 | ||
361 | while (pse_depth > se_depth) { | |
362 | pse_depth--; | |
363 | *pse = parent_entity(*pse); | |
364 | } | |
365 | ||
366 | while (!is_same_group(*se, *pse)) { | |
367 | *se = parent_entity(*se); | |
368 | *pse = parent_entity(*pse); | |
369 | } | |
370 | } | |
371 | ||
8f48894f PZ |
372 | #else /* !CONFIG_FAIR_GROUP_SCHED */ |
373 | ||
374 | static inline struct task_struct *task_of(struct sched_entity *se) | |
375 | { | |
376 | return container_of(se, struct task_struct, se); | |
377 | } | |
bf0f6f24 | 378 | |
62160e3f IM |
379 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
380 | { | |
381 | return container_of(cfs_rq, struct rq, cfs); | |
bf0f6f24 IM |
382 | } |
383 | ||
384 | #define entity_is_task(se) 1 | |
385 | ||
b758149c PZ |
386 | #define for_each_sched_entity(se) \ |
387 | for (; se; se = NULL) | |
bf0f6f24 | 388 | |
b758149c | 389 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) |
bf0f6f24 | 390 | { |
b758149c | 391 | return &task_rq(p)->cfs; |
bf0f6f24 IM |
392 | } |
393 | ||
b758149c PZ |
394 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) |
395 | { | |
396 | struct task_struct *p = task_of(se); | |
397 | struct rq *rq = task_rq(p); | |
398 | ||
399 | return &rq->cfs; | |
400 | } | |
401 | ||
402 | /* runqueue "owned" by this group */ | |
403 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
404 | { | |
405 | return NULL; | |
406 | } | |
407 | ||
3d4b47b4 PZ |
408 | static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
409 | { | |
410 | } | |
411 | ||
412 | static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) | |
413 | { | |
414 | } | |
415 | ||
b758149c PZ |
416 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
417 | for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) | |
418 | ||
b758149c PZ |
419 | static inline struct sched_entity *parent_entity(struct sched_entity *se) |
420 | { | |
421 | return NULL; | |
422 | } | |
423 | ||
464b7527 PZ |
424 | static inline void |
425 | find_matching_se(struct sched_entity **se, struct sched_entity **pse) | |
426 | { | |
427 | } | |
428 | ||
b758149c PZ |
429 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
430 | ||
6c16a6dc | 431 | static __always_inline |
9dbdb155 | 432 | void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec); |
bf0f6f24 IM |
433 | |
434 | /************************************************************** | |
435 | * Scheduling class tree data structure manipulation methods: | |
436 | */ | |
437 | ||
1bf08230 | 438 | static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime) |
02e0431a | 439 | { |
1bf08230 | 440 | s64 delta = (s64)(vruntime - max_vruntime); |
368059a9 | 441 | if (delta > 0) |
1bf08230 | 442 | max_vruntime = vruntime; |
02e0431a | 443 | |
1bf08230 | 444 | return max_vruntime; |
02e0431a PZ |
445 | } |
446 | ||
0702e3eb | 447 | static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime) |
b0ffd246 PZ |
448 | { |
449 | s64 delta = (s64)(vruntime - min_vruntime); | |
450 | if (delta < 0) | |
451 | min_vruntime = vruntime; | |
452 | ||
453 | return min_vruntime; | |
454 | } | |
455 | ||
54fdc581 FC |
456 | static inline int entity_before(struct sched_entity *a, |
457 | struct sched_entity *b) | |
458 | { | |
459 | return (s64)(a->vruntime - b->vruntime) < 0; | |
460 | } | |
461 | ||
1af5f730 PZ |
462 | static void update_min_vruntime(struct cfs_rq *cfs_rq) |
463 | { | |
464 | u64 vruntime = cfs_rq->min_vruntime; | |
465 | ||
466 | if (cfs_rq->curr) | |
467 | vruntime = cfs_rq->curr->vruntime; | |
468 | ||
469 | if (cfs_rq->rb_leftmost) { | |
470 | struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost, | |
471 | struct sched_entity, | |
472 | run_node); | |
473 | ||
e17036da | 474 | if (!cfs_rq->curr) |
1af5f730 PZ |
475 | vruntime = se->vruntime; |
476 | else | |
477 | vruntime = min_vruntime(vruntime, se->vruntime); | |
478 | } | |
479 | ||
1bf08230 | 480 | /* ensure we never gain time by being placed backwards. */ |
1af5f730 | 481 | cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); |
3fe1698b PZ |
482 | #ifndef CONFIG_64BIT |
483 | smp_wmb(); | |
484 | cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; | |
485 | #endif | |
1af5f730 PZ |
486 | } |
487 | ||
bf0f6f24 IM |
488 | /* |
489 | * Enqueue an entity into the rb-tree: | |
490 | */ | |
0702e3eb | 491 | static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 IM |
492 | { |
493 | struct rb_node **link = &cfs_rq->tasks_timeline.rb_node; | |
494 | struct rb_node *parent = NULL; | |
495 | struct sched_entity *entry; | |
bf0f6f24 IM |
496 | int leftmost = 1; |
497 | ||
498 | /* | |
499 | * Find the right place in the rbtree: | |
500 | */ | |
501 | while (*link) { | |
502 | parent = *link; | |
503 | entry = rb_entry(parent, struct sched_entity, run_node); | |
504 | /* | |
505 | * We dont care about collisions. Nodes with | |
506 | * the same key stay together. | |
507 | */ | |
2bd2d6f2 | 508 | if (entity_before(se, entry)) { |
bf0f6f24 IM |
509 | link = &parent->rb_left; |
510 | } else { | |
511 | link = &parent->rb_right; | |
512 | leftmost = 0; | |
513 | } | |
514 | } | |
515 | ||
516 | /* | |
517 | * Maintain a cache of leftmost tree entries (it is frequently | |
518 | * used): | |
519 | */ | |
1af5f730 | 520 | if (leftmost) |
57cb499d | 521 | cfs_rq->rb_leftmost = &se->run_node; |
bf0f6f24 IM |
522 | |
523 | rb_link_node(&se->run_node, parent, link); | |
524 | rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline); | |
bf0f6f24 IM |
525 | } |
526 | ||
0702e3eb | 527 | static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 528 | { |
3fe69747 PZ |
529 | if (cfs_rq->rb_leftmost == &se->run_node) { |
530 | struct rb_node *next_node; | |
3fe69747 PZ |
531 | |
532 | next_node = rb_next(&se->run_node); | |
533 | cfs_rq->rb_leftmost = next_node; | |
3fe69747 | 534 | } |
e9acbff6 | 535 | |
bf0f6f24 | 536 | rb_erase(&se->run_node, &cfs_rq->tasks_timeline); |
bf0f6f24 IM |
537 | } |
538 | ||
029632fb | 539 | struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq) |
bf0f6f24 | 540 | { |
f4b6755f PZ |
541 | struct rb_node *left = cfs_rq->rb_leftmost; |
542 | ||
543 | if (!left) | |
544 | return NULL; | |
545 | ||
546 | return rb_entry(left, struct sched_entity, run_node); | |
bf0f6f24 IM |
547 | } |
548 | ||
ac53db59 RR |
549 | static struct sched_entity *__pick_next_entity(struct sched_entity *se) |
550 | { | |
551 | struct rb_node *next = rb_next(&se->run_node); | |
552 | ||
553 | if (!next) | |
554 | return NULL; | |
555 | ||
556 | return rb_entry(next, struct sched_entity, run_node); | |
557 | } | |
558 | ||
559 | #ifdef CONFIG_SCHED_DEBUG | |
029632fb | 560 | struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) |
aeb73b04 | 561 | { |
7eee3e67 | 562 | struct rb_node *last = rb_last(&cfs_rq->tasks_timeline); |
aeb73b04 | 563 | |
70eee74b BS |
564 | if (!last) |
565 | return NULL; | |
7eee3e67 IM |
566 | |
567 | return rb_entry(last, struct sched_entity, run_node); | |
aeb73b04 PZ |
568 | } |
569 | ||
bf0f6f24 IM |
570 | /************************************************************** |
571 | * Scheduling class statistics methods: | |
572 | */ | |
573 | ||
acb4a848 | 574 | int sched_proc_update_handler(struct ctl_table *table, int write, |
8d65af78 | 575 | void __user *buffer, size_t *lenp, |
b2be5e96 PZ |
576 | loff_t *ppos) |
577 | { | |
8d65af78 | 578 | int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
acb4a848 | 579 | int factor = get_update_sysctl_factor(); |
b2be5e96 PZ |
580 | |
581 | if (ret || !write) | |
582 | return ret; | |
583 | ||
584 | sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency, | |
585 | sysctl_sched_min_granularity); | |
586 | ||
acb4a848 CE |
587 | #define WRT_SYSCTL(name) \ |
588 | (normalized_sysctl_##name = sysctl_##name / (factor)) | |
589 | WRT_SYSCTL(sched_min_granularity); | |
590 | WRT_SYSCTL(sched_latency); | |
591 | WRT_SYSCTL(sched_wakeup_granularity); | |
acb4a848 CE |
592 | #undef WRT_SYSCTL |
593 | ||
b2be5e96 PZ |
594 | return 0; |
595 | } | |
596 | #endif | |
647e7cac | 597 | |
a7be37ac | 598 | /* |
f9c0b095 | 599 | * delta /= w |
a7be37ac | 600 | */ |
9dbdb155 | 601 | static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se) |
a7be37ac | 602 | { |
f9c0b095 | 603 | if (unlikely(se->load.weight != NICE_0_LOAD)) |
9dbdb155 | 604 | delta = __calc_delta(delta, NICE_0_LOAD, &se->load); |
a7be37ac PZ |
605 | |
606 | return delta; | |
607 | } | |
608 | ||
647e7cac IM |
609 | /* |
610 | * The idea is to set a period in which each task runs once. | |
611 | * | |
532b1858 | 612 | * When there are too many tasks (sched_nr_latency) we have to stretch |
647e7cac IM |
613 | * this period because otherwise the slices get too small. |
614 | * | |
615 | * p = (nr <= nl) ? l : l*nr/nl | |
616 | */ | |
4d78e7b6 PZ |
617 | static u64 __sched_period(unsigned long nr_running) |
618 | { | |
619 | u64 period = sysctl_sched_latency; | |
b2be5e96 | 620 | unsigned long nr_latency = sched_nr_latency; |
4d78e7b6 PZ |
621 | |
622 | if (unlikely(nr_running > nr_latency)) { | |
4bf0b771 | 623 | period = sysctl_sched_min_granularity; |
4d78e7b6 | 624 | period *= nr_running; |
4d78e7b6 PZ |
625 | } |
626 | ||
627 | return period; | |
628 | } | |
629 | ||
647e7cac IM |
630 | /* |
631 | * We calculate the wall-time slice from the period by taking a part | |
632 | * proportional to the weight. | |
633 | * | |
f9c0b095 | 634 | * s = p*P[w/rw] |
647e7cac | 635 | */ |
6d0f0ebd | 636 | static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
21805085 | 637 | { |
0a582440 | 638 | u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq); |
f9c0b095 | 639 | |
0a582440 | 640 | for_each_sched_entity(se) { |
6272d68c | 641 | struct load_weight *load; |
3104bf03 | 642 | struct load_weight lw; |
6272d68c LM |
643 | |
644 | cfs_rq = cfs_rq_of(se); | |
645 | load = &cfs_rq->load; | |
f9c0b095 | 646 | |
0a582440 | 647 | if (unlikely(!se->on_rq)) { |
3104bf03 | 648 | lw = cfs_rq->load; |
0a582440 MG |
649 | |
650 | update_load_add(&lw, se->load.weight); | |
651 | load = &lw; | |
652 | } | |
9dbdb155 | 653 | slice = __calc_delta(slice, se->load.weight, load); |
0a582440 MG |
654 | } |
655 | return slice; | |
bf0f6f24 IM |
656 | } |
657 | ||
647e7cac | 658 | /* |
660cc00f | 659 | * We calculate the vruntime slice of a to-be-inserted task. |
647e7cac | 660 | * |
f9c0b095 | 661 | * vs = s/w |
647e7cac | 662 | */ |
f9c0b095 | 663 | static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
67e9fb2a | 664 | { |
f9c0b095 | 665 | return calc_delta_fair(sched_slice(cfs_rq, se), se); |
a7be37ac PZ |
666 | } |
667 | ||
a75cdaa9 | 668 | #ifdef CONFIG_SMP |
ba7e5a27 | 669 | static int select_idle_sibling(struct task_struct *p, int cpu); |
fb13c7ee MG |
670 | static unsigned long task_h_load(struct task_struct *p); |
671 | ||
a75cdaa9 | 672 | static inline void __update_task_entity_contrib(struct sched_entity *se); |
36ee28e4 | 673 | static inline void __update_task_entity_utilization(struct sched_entity *se); |
a75cdaa9 AS |
674 | |
675 | /* Give new task start runnable values to heavy its load in infant time */ | |
676 | void init_task_runnable_average(struct task_struct *p) | |
677 | { | |
678 | u32 slice; | |
679 | ||
a75cdaa9 | 680 | slice = sched_slice(task_cfs_rq(p), &p->se) >> 10; |
36ee28e4 VG |
681 | p->se.avg.runnable_avg_sum = p->se.avg.running_avg_sum = slice; |
682 | p->se.avg.avg_period = slice; | |
a75cdaa9 | 683 | __update_task_entity_contrib(&p->se); |
36ee28e4 | 684 | __update_task_entity_utilization(&p->se); |
a75cdaa9 AS |
685 | } |
686 | #else | |
687 | void init_task_runnable_average(struct task_struct *p) | |
688 | { | |
689 | } | |
690 | #endif | |
691 | ||
bf0f6f24 | 692 | /* |
9dbdb155 | 693 | * Update the current task's runtime statistics. |
bf0f6f24 | 694 | */ |
b7cc0896 | 695 | static void update_curr(struct cfs_rq *cfs_rq) |
bf0f6f24 | 696 | { |
429d43bc | 697 | struct sched_entity *curr = cfs_rq->curr; |
78becc27 | 698 | u64 now = rq_clock_task(rq_of(cfs_rq)); |
9dbdb155 | 699 | u64 delta_exec; |
bf0f6f24 IM |
700 | |
701 | if (unlikely(!curr)) | |
702 | return; | |
703 | ||
9dbdb155 PZ |
704 | delta_exec = now - curr->exec_start; |
705 | if (unlikely((s64)delta_exec <= 0)) | |
34f28ecd | 706 | return; |
bf0f6f24 | 707 | |
8ebc91d9 | 708 | curr->exec_start = now; |
d842de87 | 709 | |
9dbdb155 PZ |
710 | schedstat_set(curr->statistics.exec_max, |
711 | max(delta_exec, curr->statistics.exec_max)); | |
712 | ||
713 | curr->sum_exec_runtime += delta_exec; | |
714 | schedstat_add(cfs_rq, exec_clock, delta_exec); | |
715 | ||
716 | curr->vruntime += calc_delta_fair(delta_exec, curr); | |
717 | update_min_vruntime(cfs_rq); | |
718 | ||
d842de87 SV |
719 | if (entity_is_task(curr)) { |
720 | struct task_struct *curtask = task_of(curr); | |
721 | ||
f977bb49 | 722 | trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); |
d842de87 | 723 | cpuacct_charge(curtask, delta_exec); |
f06febc9 | 724 | account_group_exec_runtime(curtask, delta_exec); |
d842de87 | 725 | } |
ec12cb7f PT |
726 | |
727 | account_cfs_rq_runtime(cfs_rq, delta_exec); | |
bf0f6f24 IM |
728 | } |
729 | ||
6e998916 SG |
730 | static void update_curr_fair(struct rq *rq) |
731 | { | |
732 | update_curr(cfs_rq_of(&rq->curr->se)); | |
733 | } | |
734 | ||
bf0f6f24 | 735 | static inline void |
5870db5b | 736 | update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 737 | { |
78becc27 | 738 | schedstat_set(se->statistics.wait_start, rq_clock(rq_of(cfs_rq))); |
bf0f6f24 IM |
739 | } |
740 | ||
bf0f6f24 IM |
741 | /* |
742 | * Task is being enqueued - update stats: | |
743 | */ | |
d2417e5a | 744 | static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 745 | { |
bf0f6f24 IM |
746 | /* |
747 | * Are we enqueueing a waiting task? (for current tasks | |
748 | * a dequeue/enqueue event is a NOP) | |
749 | */ | |
429d43bc | 750 | if (se != cfs_rq->curr) |
5870db5b | 751 | update_stats_wait_start(cfs_rq, se); |
bf0f6f24 IM |
752 | } |
753 | ||
bf0f6f24 | 754 | static void |
9ef0a961 | 755 | update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 756 | { |
41acab88 | 757 | schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max, |
78becc27 | 758 | rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start)); |
41acab88 LDM |
759 | schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1); |
760 | schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum + | |
78becc27 | 761 | rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start); |
768d0c27 PZ |
762 | #ifdef CONFIG_SCHEDSTATS |
763 | if (entity_is_task(se)) { | |
764 | trace_sched_stat_wait(task_of(se), | |
78becc27 | 765 | rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start); |
768d0c27 PZ |
766 | } |
767 | #endif | |
41acab88 | 768 | schedstat_set(se->statistics.wait_start, 0); |
bf0f6f24 IM |
769 | } |
770 | ||
771 | static inline void | |
19b6a2e3 | 772 | update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 773 | { |
bf0f6f24 IM |
774 | /* |
775 | * Mark the end of the wait period if dequeueing a | |
776 | * waiting task: | |
777 | */ | |
429d43bc | 778 | if (se != cfs_rq->curr) |
9ef0a961 | 779 | update_stats_wait_end(cfs_rq, se); |
bf0f6f24 IM |
780 | } |
781 | ||
782 | /* | |
783 | * We are picking a new current task - update its stats: | |
784 | */ | |
785 | static inline void | |
79303e9e | 786 | update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 IM |
787 | { |
788 | /* | |
789 | * We are starting a new run period: | |
790 | */ | |
78becc27 | 791 | se->exec_start = rq_clock_task(rq_of(cfs_rq)); |
bf0f6f24 IM |
792 | } |
793 | ||
bf0f6f24 IM |
794 | /************************************************** |
795 | * Scheduling class queueing methods: | |
796 | */ | |
797 | ||
cbee9f88 PZ |
798 | #ifdef CONFIG_NUMA_BALANCING |
799 | /* | |
598f0ec0 MG |
800 | * Approximate time to scan a full NUMA task in ms. The task scan period is |
801 | * calculated based on the tasks virtual memory size and | |
802 | * numa_balancing_scan_size. | |
cbee9f88 | 803 | */ |
598f0ec0 MG |
804 | unsigned int sysctl_numa_balancing_scan_period_min = 1000; |
805 | unsigned int sysctl_numa_balancing_scan_period_max = 60000; | |
6e5fb223 PZ |
806 | |
807 | /* Portion of address space to scan in MB */ | |
808 | unsigned int sysctl_numa_balancing_scan_size = 256; | |
cbee9f88 | 809 | |
4b96a29b PZ |
810 | /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */ |
811 | unsigned int sysctl_numa_balancing_scan_delay = 1000; | |
812 | ||
598f0ec0 MG |
813 | static unsigned int task_nr_scan_windows(struct task_struct *p) |
814 | { | |
815 | unsigned long rss = 0; | |
816 | unsigned long nr_scan_pages; | |
817 | ||
818 | /* | |
819 | * Calculations based on RSS as non-present and empty pages are skipped | |
820 | * by the PTE scanner and NUMA hinting faults should be trapped based | |
821 | * on resident pages | |
822 | */ | |
823 | nr_scan_pages = sysctl_numa_balancing_scan_size << (20 - PAGE_SHIFT); | |
824 | rss = get_mm_rss(p->mm); | |
825 | if (!rss) | |
826 | rss = nr_scan_pages; | |
827 | ||
828 | rss = round_up(rss, nr_scan_pages); | |
829 | return rss / nr_scan_pages; | |
830 | } | |
831 | ||
832 | /* For sanitys sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */ | |
833 | #define MAX_SCAN_WINDOW 2560 | |
834 | ||
835 | static unsigned int task_scan_min(struct task_struct *p) | |
836 | { | |
64192658 | 837 | unsigned int scan_size = ACCESS_ONCE(sysctl_numa_balancing_scan_size); |
598f0ec0 MG |
838 | unsigned int scan, floor; |
839 | unsigned int windows = 1; | |
840 | ||
64192658 KT |
841 | if (scan_size < MAX_SCAN_WINDOW) |
842 | windows = MAX_SCAN_WINDOW / scan_size; | |
598f0ec0 MG |
843 | floor = 1000 / windows; |
844 | ||
845 | scan = sysctl_numa_balancing_scan_period_min / task_nr_scan_windows(p); | |
846 | return max_t(unsigned int, floor, scan); | |
847 | } | |
848 | ||
849 | static unsigned int task_scan_max(struct task_struct *p) | |
850 | { | |
851 | unsigned int smin = task_scan_min(p); | |
852 | unsigned int smax; | |
853 | ||
854 | /* Watch for min being lower than max due to floor calculations */ | |
855 | smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p); | |
856 | return max(smin, smax); | |
857 | } | |
858 | ||
0ec8aa00 PZ |
859 | static void account_numa_enqueue(struct rq *rq, struct task_struct *p) |
860 | { | |
861 | rq->nr_numa_running += (p->numa_preferred_nid != -1); | |
862 | rq->nr_preferred_running += (p->numa_preferred_nid == task_node(p)); | |
863 | } | |
864 | ||
865 | static void account_numa_dequeue(struct rq *rq, struct task_struct *p) | |
866 | { | |
867 | rq->nr_numa_running -= (p->numa_preferred_nid != -1); | |
868 | rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p)); | |
869 | } | |
870 | ||
8c8a743c PZ |
871 | struct numa_group { |
872 | atomic_t refcount; | |
873 | ||
874 | spinlock_t lock; /* nr_tasks, tasks */ | |
875 | int nr_tasks; | |
e29cf08b | 876 | pid_t gid; |
8c8a743c PZ |
877 | |
878 | struct rcu_head rcu; | |
20e07dea | 879 | nodemask_t active_nodes; |
989348b5 | 880 | unsigned long total_faults; |
7e2703e6 RR |
881 | /* |
882 | * Faults_cpu is used to decide whether memory should move | |
883 | * towards the CPU. As a consequence, these stats are weighted | |
884 | * more by CPU use than by memory faults. | |
885 | */ | |
50ec8a40 | 886 | unsigned long *faults_cpu; |
989348b5 | 887 | unsigned long faults[0]; |
8c8a743c PZ |
888 | }; |
889 | ||
be1e4e76 RR |
890 | /* Shared or private faults. */ |
891 | #define NR_NUMA_HINT_FAULT_TYPES 2 | |
892 | ||
893 | /* Memory and CPU locality */ | |
894 | #define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2) | |
895 | ||
896 | /* Averaged statistics, and temporary buffers. */ | |
897 | #define NR_NUMA_HINT_FAULT_BUCKETS (NR_NUMA_HINT_FAULT_STATS * 2) | |
898 | ||
e29cf08b MG |
899 | pid_t task_numa_group_id(struct task_struct *p) |
900 | { | |
901 | return p->numa_group ? p->numa_group->gid : 0; | |
902 | } | |
903 | ||
44dba3d5 IM |
904 | /* |
905 | * The averaged statistics, shared & private, memory & cpu, | |
906 | * occupy the first half of the array. The second half of the | |
907 | * array is for current counters, which are averaged into the | |
908 | * first set by task_numa_placement. | |
909 | */ | |
910 | static inline int task_faults_idx(enum numa_faults_stats s, int nid, int priv) | |
ac8e895b | 911 | { |
44dba3d5 | 912 | return NR_NUMA_HINT_FAULT_TYPES * (s * nr_node_ids + nid) + priv; |
ac8e895b MG |
913 | } |
914 | ||
915 | static inline unsigned long task_faults(struct task_struct *p, int nid) | |
916 | { | |
44dba3d5 | 917 | if (!p->numa_faults) |
ac8e895b MG |
918 | return 0; |
919 | ||
44dba3d5 IM |
920 | return p->numa_faults[task_faults_idx(NUMA_MEM, nid, 0)] + |
921 | p->numa_faults[task_faults_idx(NUMA_MEM, nid, 1)]; | |
ac8e895b MG |
922 | } |
923 | ||
83e1d2cd MG |
924 | static inline unsigned long group_faults(struct task_struct *p, int nid) |
925 | { | |
926 | if (!p->numa_group) | |
927 | return 0; | |
928 | ||
44dba3d5 IM |
929 | return p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 0)] + |
930 | p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 1)]; | |
83e1d2cd MG |
931 | } |
932 | ||
20e07dea RR |
933 | static inline unsigned long group_faults_cpu(struct numa_group *group, int nid) |
934 | { | |
44dba3d5 IM |
935 | return group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 0)] + |
936 | group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 1)]; | |
20e07dea RR |
937 | } |
938 | ||
6c6b1193 RR |
939 | /* Handle placement on systems where not all nodes are directly connected. */ |
940 | static unsigned long score_nearby_nodes(struct task_struct *p, int nid, | |
941 | int maxdist, bool task) | |
942 | { | |
943 | unsigned long score = 0; | |
944 | int node; | |
945 | ||
946 | /* | |
947 | * All nodes are directly connected, and the same distance | |
948 | * from each other. No need for fancy placement algorithms. | |
949 | */ | |
950 | if (sched_numa_topology_type == NUMA_DIRECT) | |
951 | return 0; | |
952 | ||
953 | /* | |
954 | * This code is called for each node, introducing N^2 complexity, | |
955 | * which should be ok given the number of nodes rarely exceeds 8. | |
956 | */ | |
957 | for_each_online_node(node) { | |
958 | unsigned long faults; | |
959 | int dist = node_distance(nid, node); | |
960 | ||
961 | /* | |
962 | * The furthest away nodes in the system are not interesting | |
963 | * for placement; nid was already counted. | |
964 | */ | |
965 | if (dist == sched_max_numa_distance || node == nid) | |
966 | continue; | |
967 | ||
968 | /* | |
969 | * On systems with a backplane NUMA topology, compare groups | |
970 | * of nodes, and move tasks towards the group with the most | |
971 | * memory accesses. When comparing two nodes at distance | |
972 | * "hoplimit", only nodes closer by than "hoplimit" are part | |
973 | * of each group. Skip other nodes. | |
974 | */ | |
975 | if (sched_numa_topology_type == NUMA_BACKPLANE && | |
976 | dist > maxdist) | |
977 | continue; | |
978 | ||
979 | /* Add up the faults from nearby nodes. */ | |
980 | if (task) | |
981 | faults = task_faults(p, node); | |
982 | else | |
983 | faults = group_faults(p, node); | |
984 | ||
985 | /* | |
986 | * On systems with a glueless mesh NUMA topology, there are | |
987 | * no fixed "groups of nodes". Instead, nodes that are not | |
988 | * directly connected bounce traffic through intermediate | |
989 | * nodes; a numa_group can occupy any set of nodes. | |
990 | * The further away a node is, the less the faults count. | |
991 | * This seems to result in good task placement. | |
992 | */ | |
993 | if (sched_numa_topology_type == NUMA_GLUELESS_MESH) { | |
994 | faults *= (sched_max_numa_distance - dist); | |
995 | faults /= (sched_max_numa_distance - LOCAL_DISTANCE); | |
996 | } | |
997 | ||
998 | score += faults; | |
999 | } | |
1000 | ||
1001 | return score; | |
1002 | } | |
1003 | ||
83e1d2cd MG |
1004 | /* |
1005 | * These return the fraction of accesses done by a particular task, or | |
1006 | * task group, on a particular numa node. The group weight is given a | |
1007 | * larger multiplier, in order to group tasks together that are almost | |
1008 | * evenly spread out between numa nodes. | |
1009 | */ | |
7bd95320 RR |
1010 | static inline unsigned long task_weight(struct task_struct *p, int nid, |
1011 | int dist) | |
83e1d2cd | 1012 | { |
7bd95320 | 1013 | unsigned long faults, total_faults; |
83e1d2cd | 1014 | |
44dba3d5 | 1015 | if (!p->numa_faults) |
83e1d2cd MG |
1016 | return 0; |
1017 | ||
1018 | total_faults = p->total_numa_faults; | |
1019 | ||
1020 | if (!total_faults) | |
1021 | return 0; | |
1022 | ||
7bd95320 | 1023 | faults = task_faults(p, nid); |
6c6b1193 RR |
1024 | faults += score_nearby_nodes(p, nid, dist, true); |
1025 | ||
7bd95320 | 1026 | return 1000 * faults / total_faults; |
83e1d2cd MG |
1027 | } |
1028 | ||
7bd95320 RR |
1029 | static inline unsigned long group_weight(struct task_struct *p, int nid, |
1030 | int dist) | |
83e1d2cd | 1031 | { |
7bd95320 RR |
1032 | unsigned long faults, total_faults; |
1033 | ||
1034 | if (!p->numa_group) | |
1035 | return 0; | |
1036 | ||
1037 | total_faults = p->numa_group->total_faults; | |
1038 | ||
1039 | if (!total_faults) | |
83e1d2cd MG |
1040 | return 0; |
1041 | ||
7bd95320 | 1042 | faults = group_faults(p, nid); |
6c6b1193 RR |
1043 | faults += score_nearby_nodes(p, nid, dist, false); |
1044 | ||
7bd95320 | 1045 | return 1000 * faults / total_faults; |
83e1d2cd MG |
1046 | } |
1047 | ||
10f39042 RR |
1048 | bool should_numa_migrate_memory(struct task_struct *p, struct page * page, |
1049 | int src_nid, int dst_cpu) | |
1050 | { | |
1051 | struct numa_group *ng = p->numa_group; | |
1052 | int dst_nid = cpu_to_node(dst_cpu); | |
1053 | int last_cpupid, this_cpupid; | |
1054 | ||
1055 | this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid); | |
1056 | ||
1057 | /* | |
1058 | * Multi-stage node selection is used in conjunction with a periodic | |
1059 | * migration fault to build a temporal task<->page relation. By using | |
1060 | * a two-stage filter we remove short/unlikely relations. | |
1061 | * | |
1062 | * Using P(p) ~ n_p / n_t as per frequentist probability, we can equate | |
1063 | * a task's usage of a particular page (n_p) per total usage of this | |
1064 | * page (n_t) (in a given time-span) to a probability. | |
1065 | * | |
1066 | * Our periodic faults will sample this probability and getting the | |
1067 | * same result twice in a row, given these samples are fully | |
1068 | * independent, is then given by P(n)^2, provided our sample period | |
1069 | * is sufficiently short compared to the usage pattern. | |
1070 | * | |
1071 | * This quadric squishes small probabilities, making it less likely we | |
1072 | * act on an unlikely task<->page relation. | |
1073 | */ | |
1074 | last_cpupid = page_cpupid_xchg_last(page, this_cpupid); | |
1075 | if (!cpupid_pid_unset(last_cpupid) && | |
1076 | cpupid_to_nid(last_cpupid) != dst_nid) | |
1077 | return false; | |
1078 | ||
1079 | /* Always allow migrate on private faults */ | |
1080 | if (cpupid_match_pid(p, last_cpupid)) | |
1081 | return true; | |
1082 | ||
1083 | /* A shared fault, but p->numa_group has not been set up yet. */ | |
1084 | if (!ng) | |
1085 | return true; | |
1086 | ||
1087 | /* | |
1088 | * Do not migrate if the destination is not a node that | |
1089 | * is actively used by this numa group. | |
1090 | */ | |
1091 | if (!node_isset(dst_nid, ng->active_nodes)) | |
1092 | return false; | |
1093 | ||
1094 | /* | |
1095 | * Source is a node that is not actively used by this | |
1096 | * numa group, while the destination is. Migrate. | |
1097 | */ | |
1098 | if (!node_isset(src_nid, ng->active_nodes)) | |
1099 | return true; | |
1100 | ||
1101 | /* | |
1102 | * Both source and destination are nodes in active | |
1103 | * use by this numa group. Maximize memory bandwidth | |
1104 | * by migrating from more heavily used groups, to less | |
1105 | * heavily used ones, spreading the load around. | |
1106 | * Use a 1/4 hysteresis to avoid spurious page movement. | |
1107 | */ | |
1108 | return group_faults(p, dst_nid) < (group_faults(p, src_nid) * 3 / 4); | |
1109 | } | |
1110 | ||
e6628d5b | 1111 | static unsigned long weighted_cpuload(const int cpu); |
58d081b5 MG |
1112 | static unsigned long source_load(int cpu, int type); |
1113 | static unsigned long target_load(int cpu, int type); | |
ced549fa | 1114 | static unsigned long capacity_of(int cpu); |
58d081b5 MG |
1115 | static long effective_load(struct task_group *tg, int cpu, long wl, long wg); |
1116 | ||
fb13c7ee | 1117 | /* Cached statistics for all CPUs within a node */ |
58d081b5 | 1118 | struct numa_stats { |
fb13c7ee | 1119 | unsigned long nr_running; |
58d081b5 | 1120 | unsigned long load; |
fb13c7ee MG |
1121 | |
1122 | /* Total compute capacity of CPUs on a node */ | |
5ef20ca1 | 1123 | unsigned long compute_capacity; |
fb13c7ee MG |
1124 | |
1125 | /* Approximate capacity in terms of runnable tasks on a node */ | |
5ef20ca1 | 1126 | unsigned long task_capacity; |
1b6a7495 | 1127 | int has_free_capacity; |
58d081b5 | 1128 | }; |
e6628d5b | 1129 | |
fb13c7ee MG |
1130 | /* |
1131 | * XXX borrowed from update_sg_lb_stats | |
1132 | */ | |
1133 | static void update_numa_stats(struct numa_stats *ns, int nid) | |
1134 | { | |
83d7f242 RR |
1135 | int smt, cpu, cpus = 0; |
1136 | unsigned long capacity; | |
fb13c7ee MG |
1137 | |
1138 | memset(ns, 0, sizeof(*ns)); | |
1139 | for_each_cpu(cpu, cpumask_of_node(nid)) { | |
1140 | struct rq *rq = cpu_rq(cpu); | |
1141 | ||
1142 | ns->nr_running += rq->nr_running; | |
1143 | ns->load += weighted_cpuload(cpu); | |
ced549fa | 1144 | ns->compute_capacity += capacity_of(cpu); |
5eca82a9 PZ |
1145 | |
1146 | cpus++; | |
fb13c7ee MG |
1147 | } |
1148 | ||
5eca82a9 PZ |
1149 | /* |
1150 | * If we raced with hotplug and there are no CPUs left in our mask | |
1151 | * the @ns structure is NULL'ed and task_numa_compare() will | |
1152 | * not find this node attractive. | |
1153 | * | |
1b6a7495 NP |
1154 | * We'll either bail at !has_free_capacity, or we'll detect a huge |
1155 | * imbalance and bail there. | |
5eca82a9 PZ |
1156 | */ |
1157 | if (!cpus) | |
1158 | return; | |
1159 | ||
83d7f242 RR |
1160 | /* smt := ceil(cpus / capacity), assumes: 1 < smt_power < 2 */ |
1161 | smt = DIV_ROUND_UP(SCHED_CAPACITY_SCALE * cpus, ns->compute_capacity); | |
1162 | capacity = cpus / smt; /* cores */ | |
1163 | ||
1164 | ns->task_capacity = min_t(unsigned, capacity, | |
1165 | DIV_ROUND_CLOSEST(ns->compute_capacity, SCHED_CAPACITY_SCALE)); | |
1b6a7495 | 1166 | ns->has_free_capacity = (ns->nr_running < ns->task_capacity); |
fb13c7ee MG |
1167 | } |
1168 | ||
58d081b5 MG |
1169 | struct task_numa_env { |
1170 | struct task_struct *p; | |
e6628d5b | 1171 | |
58d081b5 MG |
1172 | int src_cpu, src_nid; |
1173 | int dst_cpu, dst_nid; | |
e6628d5b | 1174 | |
58d081b5 | 1175 | struct numa_stats src_stats, dst_stats; |
e6628d5b | 1176 | |
40ea2b42 | 1177 | int imbalance_pct; |
7bd95320 | 1178 | int dist; |
fb13c7ee MG |
1179 | |
1180 | struct task_struct *best_task; | |
1181 | long best_imp; | |
58d081b5 MG |
1182 | int best_cpu; |
1183 | }; | |
1184 | ||
fb13c7ee MG |
1185 | static void task_numa_assign(struct task_numa_env *env, |
1186 | struct task_struct *p, long imp) | |
1187 | { | |
1188 | if (env->best_task) | |
1189 | put_task_struct(env->best_task); | |
1190 | if (p) | |
1191 | get_task_struct(p); | |
1192 | ||
1193 | env->best_task = p; | |
1194 | env->best_imp = imp; | |
1195 | env->best_cpu = env->dst_cpu; | |
1196 | } | |
1197 | ||
28a21745 | 1198 | static bool load_too_imbalanced(long src_load, long dst_load, |
e63da036 RR |
1199 | struct task_numa_env *env) |
1200 | { | |
28a21745 | 1201 | long src_capacity, dst_capacity; |
095bebf6 RR |
1202 | long orig_src_load; |
1203 | long load_a, load_b; | |
1204 | long moved_load; | |
1205 | long imb; | |
28a21745 RR |
1206 | |
1207 | /* | |
1208 | * The load is corrected for the CPU capacity available on each node. | |
1209 | * | |
1210 | * src_load dst_load | |
1211 | * ------------ vs --------- | |
1212 | * src_capacity dst_capacity | |
1213 | */ | |
1214 | src_capacity = env->src_stats.compute_capacity; | |
1215 | dst_capacity = env->dst_stats.compute_capacity; | |
e63da036 RR |
1216 | |
1217 | /* We care about the slope of the imbalance, not the direction. */ | |
095bebf6 RR |
1218 | load_a = dst_load; |
1219 | load_b = src_load; | |
1220 | if (load_a < load_b) | |
1221 | swap(load_a, load_b); | |
e63da036 RR |
1222 | |
1223 | /* Is the difference below the threshold? */ | |
095bebf6 RR |
1224 | imb = load_a * src_capacity * 100 - |
1225 | load_b * dst_capacity * env->imbalance_pct; | |
e63da036 RR |
1226 | if (imb <= 0) |
1227 | return false; | |
1228 | ||
1229 | /* | |
1230 | * The imbalance is above the allowed threshold. | |
095bebf6 RR |
1231 | * Allow a move that brings us closer to a balanced situation, |
1232 | * without moving things past the point of balance. | |
e63da036 | 1233 | */ |
28a21745 | 1234 | orig_src_load = env->src_stats.load; |
28a21745 | 1235 | |
095bebf6 RR |
1236 | /* |
1237 | * In a task swap, there will be one load moving from src to dst, | |
1238 | * and another moving back. This is the net sum of both moves. | |
1239 | * A simple task move will always have a positive value. | |
1240 | * Allow the move if it brings the system closer to a balanced | |
1241 | * situation, without crossing over the balance point. | |
1242 | */ | |
1243 | moved_load = orig_src_load - src_load; | |
e63da036 | 1244 | |
095bebf6 RR |
1245 | if (moved_load > 0) |
1246 | /* Moving src -> dst. Did we overshoot balance? */ | |
1247 | return src_load * dst_capacity < dst_load * src_capacity; | |
1248 | else | |
1249 | /* Moving dst -> src. Did we overshoot balance? */ | |
1250 | return dst_load * src_capacity < src_load * dst_capacity; | |
e63da036 RR |
1251 | } |
1252 | ||
fb13c7ee MG |
1253 | /* |
1254 | * This checks if the overall compute and NUMA accesses of the system would | |
1255 | * be improved if the source tasks was migrated to the target dst_cpu taking | |
1256 | * into account that it might be best if task running on the dst_cpu should | |
1257 | * be exchanged with the source task | |
1258 | */ | |
887c290e RR |
1259 | static void task_numa_compare(struct task_numa_env *env, |
1260 | long taskimp, long groupimp) | |
fb13c7ee MG |
1261 | { |
1262 | struct rq *src_rq = cpu_rq(env->src_cpu); | |
1263 | struct rq *dst_rq = cpu_rq(env->dst_cpu); | |
1264 | struct task_struct *cur; | |
28a21745 | 1265 | long src_load, dst_load; |
fb13c7ee | 1266 | long load; |
1c5d3eb3 | 1267 | long imp = env->p->numa_group ? groupimp : taskimp; |
0132c3e1 | 1268 | long moveimp = imp; |
7bd95320 | 1269 | int dist = env->dist; |
fb13c7ee MG |
1270 | |
1271 | rcu_read_lock(); | |
1effd9f1 KT |
1272 | |
1273 | raw_spin_lock_irq(&dst_rq->lock); | |
1274 | cur = dst_rq->curr; | |
1275 | /* | |
1276 | * No need to move the exiting task, and this ensures that ->curr | |
1277 | * wasn't reaped and thus get_task_struct() in task_numa_assign() | |
1278 | * is safe under RCU read lock. | |
1279 | * Note that rcu_read_lock() itself can't protect from the final | |
1280 | * put_task_struct() after the last schedule(). | |
1281 | */ | |
1282 | if ((cur->flags & PF_EXITING) || is_idle_task(cur)) | |
fb13c7ee | 1283 | cur = NULL; |
1effd9f1 | 1284 | raw_spin_unlock_irq(&dst_rq->lock); |
fb13c7ee | 1285 | |
7af68335 PZ |
1286 | /* |
1287 | * Because we have preemption enabled we can get migrated around and | |
1288 | * end try selecting ourselves (current == env->p) as a swap candidate. | |
1289 | */ | |
1290 | if (cur == env->p) | |
1291 | goto unlock; | |
1292 | ||
fb13c7ee MG |
1293 | /* |
1294 | * "imp" is the fault differential for the source task between the | |
1295 | * source and destination node. Calculate the total differential for | |
1296 | * the source task and potential destination task. The more negative | |
1297 | * the value is, the more rmeote accesses that would be expected to | |
1298 | * be incurred if the tasks were swapped. | |
1299 | */ | |
1300 | if (cur) { | |
1301 | /* Skip this swap candidate if cannot move to the source cpu */ | |
1302 | if (!cpumask_test_cpu(env->src_cpu, tsk_cpus_allowed(cur))) | |
1303 | goto unlock; | |
1304 | ||
887c290e RR |
1305 | /* |
1306 | * If dst and source tasks are in the same NUMA group, or not | |
ca28aa53 | 1307 | * in any group then look only at task weights. |
887c290e | 1308 | */ |
ca28aa53 | 1309 | if (cur->numa_group == env->p->numa_group) { |
7bd95320 RR |
1310 | imp = taskimp + task_weight(cur, env->src_nid, dist) - |
1311 | task_weight(cur, env->dst_nid, dist); | |
ca28aa53 RR |
1312 | /* |
1313 | * Add some hysteresis to prevent swapping the | |
1314 | * tasks within a group over tiny differences. | |
1315 | */ | |
1316 | if (cur->numa_group) | |
1317 | imp -= imp/16; | |
887c290e | 1318 | } else { |
ca28aa53 RR |
1319 | /* |
1320 | * Compare the group weights. If a task is all by | |
1321 | * itself (not part of a group), use the task weight | |
1322 | * instead. | |
1323 | */ | |
ca28aa53 | 1324 | if (cur->numa_group) |
7bd95320 RR |
1325 | imp += group_weight(cur, env->src_nid, dist) - |
1326 | group_weight(cur, env->dst_nid, dist); | |
ca28aa53 | 1327 | else |
7bd95320 RR |
1328 | imp += task_weight(cur, env->src_nid, dist) - |
1329 | task_weight(cur, env->dst_nid, dist); | |
887c290e | 1330 | } |
fb13c7ee MG |
1331 | } |
1332 | ||
0132c3e1 | 1333 | if (imp <= env->best_imp && moveimp <= env->best_imp) |
fb13c7ee MG |
1334 | goto unlock; |
1335 | ||
1336 | if (!cur) { | |
1337 | /* Is there capacity at our destination? */ | |
b932c03c | 1338 | if (env->src_stats.nr_running <= env->src_stats.task_capacity && |
1b6a7495 | 1339 | !env->dst_stats.has_free_capacity) |
fb13c7ee MG |
1340 | goto unlock; |
1341 | ||
1342 | goto balance; | |
1343 | } | |
1344 | ||
1345 | /* Balance doesn't matter much if we're running a task per cpu */ | |
0132c3e1 RR |
1346 | if (imp > env->best_imp && src_rq->nr_running == 1 && |
1347 | dst_rq->nr_running == 1) | |
fb13c7ee MG |
1348 | goto assign; |
1349 | ||
1350 | /* | |
1351 | * In the overloaded case, try and keep the load balanced. | |
1352 | */ | |
1353 | balance: | |
e720fff6 PZ |
1354 | load = task_h_load(env->p); |
1355 | dst_load = env->dst_stats.load + load; | |
1356 | src_load = env->src_stats.load - load; | |
fb13c7ee | 1357 | |
0132c3e1 RR |
1358 | if (moveimp > imp && moveimp > env->best_imp) { |
1359 | /* | |
1360 | * If the improvement from just moving env->p direction is | |
1361 | * better than swapping tasks around, check if a move is | |
1362 | * possible. Store a slightly smaller score than moveimp, | |
1363 | * so an actually idle CPU will win. | |
1364 | */ | |
1365 | if (!load_too_imbalanced(src_load, dst_load, env)) { | |
1366 | imp = moveimp - 1; | |
1367 | cur = NULL; | |
1368 | goto assign; | |
1369 | } | |
1370 | } | |
1371 | ||
1372 | if (imp <= env->best_imp) | |
1373 | goto unlock; | |
1374 | ||
fb13c7ee | 1375 | if (cur) { |
e720fff6 PZ |
1376 | load = task_h_load(cur); |
1377 | dst_load -= load; | |
1378 | src_load += load; | |
fb13c7ee MG |
1379 | } |
1380 | ||
28a21745 | 1381 | if (load_too_imbalanced(src_load, dst_load, env)) |
fb13c7ee MG |
1382 | goto unlock; |
1383 | ||
ba7e5a27 RR |
1384 | /* |
1385 | * One idle CPU per node is evaluated for a task numa move. | |
1386 | * Call select_idle_sibling to maybe find a better one. | |
1387 | */ | |
1388 | if (!cur) | |
1389 | env->dst_cpu = select_idle_sibling(env->p, env->dst_cpu); | |
1390 | ||
fb13c7ee MG |
1391 | assign: |
1392 | task_numa_assign(env, cur, imp); | |
1393 | unlock: | |
1394 | rcu_read_unlock(); | |
1395 | } | |
1396 | ||
887c290e RR |
1397 | static void task_numa_find_cpu(struct task_numa_env *env, |
1398 | long taskimp, long groupimp) | |
2c8a50aa MG |
1399 | { |
1400 | int cpu; | |
1401 | ||
1402 | for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) { | |
1403 | /* Skip this CPU if the source task cannot migrate */ | |
1404 | if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(env->p))) | |
1405 | continue; | |
1406 | ||
1407 | env->dst_cpu = cpu; | |
887c290e | 1408 | task_numa_compare(env, taskimp, groupimp); |
2c8a50aa MG |
1409 | } |
1410 | } | |
1411 | ||
58d081b5 MG |
1412 | static int task_numa_migrate(struct task_struct *p) |
1413 | { | |
58d081b5 MG |
1414 | struct task_numa_env env = { |
1415 | .p = p, | |
fb13c7ee | 1416 | |
58d081b5 | 1417 | .src_cpu = task_cpu(p), |
b32e86b4 | 1418 | .src_nid = task_node(p), |
fb13c7ee MG |
1419 | |
1420 | .imbalance_pct = 112, | |
1421 | ||
1422 | .best_task = NULL, | |
1423 | .best_imp = 0, | |
1424 | .best_cpu = -1 | |
58d081b5 MG |
1425 | }; |
1426 | struct sched_domain *sd; | |
887c290e | 1427 | unsigned long taskweight, groupweight; |
7bd95320 | 1428 | int nid, ret, dist; |
887c290e | 1429 | long taskimp, groupimp; |
e6628d5b | 1430 | |
58d081b5 | 1431 | /* |
fb13c7ee MG |
1432 | * Pick the lowest SD_NUMA domain, as that would have the smallest |
1433 | * imbalance and would be the first to start moving tasks about. | |
1434 | * | |
1435 | * And we want to avoid any moving of tasks about, as that would create | |
1436 | * random movement of tasks -- counter the numa conditions we're trying | |
1437 | * to satisfy here. | |
58d081b5 MG |
1438 | */ |
1439 | rcu_read_lock(); | |
fb13c7ee | 1440 | sd = rcu_dereference(per_cpu(sd_numa, env.src_cpu)); |
46a73e8a RR |
1441 | if (sd) |
1442 | env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2; | |
e6628d5b MG |
1443 | rcu_read_unlock(); |
1444 | ||
46a73e8a RR |
1445 | /* |
1446 | * Cpusets can break the scheduler domain tree into smaller | |
1447 | * balance domains, some of which do not cross NUMA boundaries. | |
1448 | * Tasks that are "trapped" in such domains cannot be migrated | |
1449 | * elsewhere, so there is no point in (re)trying. | |
1450 | */ | |
1451 | if (unlikely(!sd)) { | |
de1b301a | 1452 | p->numa_preferred_nid = task_node(p); |
46a73e8a RR |
1453 | return -EINVAL; |
1454 | } | |
1455 | ||
2c8a50aa | 1456 | env.dst_nid = p->numa_preferred_nid; |
7bd95320 RR |
1457 | dist = env.dist = node_distance(env.src_nid, env.dst_nid); |
1458 | taskweight = task_weight(p, env.src_nid, dist); | |
1459 | groupweight = group_weight(p, env.src_nid, dist); | |
1460 | update_numa_stats(&env.src_stats, env.src_nid); | |
1461 | taskimp = task_weight(p, env.dst_nid, dist) - taskweight; | |
1462 | groupimp = group_weight(p, env.dst_nid, dist) - groupweight; | |
2c8a50aa | 1463 | update_numa_stats(&env.dst_stats, env.dst_nid); |
58d081b5 | 1464 | |
a43455a1 RR |
1465 | /* Try to find a spot on the preferred nid. */ |
1466 | task_numa_find_cpu(&env, taskimp, groupimp); | |
e1dda8a7 | 1467 | |
9de05d48 RR |
1468 | /* |
1469 | * Look at other nodes in these cases: | |
1470 | * - there is no space available on the preferred_nid | |
1471 | * - the task is part of a numa_group that is interleaved across | |
1472 | * multiple NUMA nodes; in order to better consolidate the group, | |
1473 | * we need to check other locations. | |
1474 | */ | |
1475 | if (env.best_cpu == -1 || (p->numa_group && | |
1476 | nodes_weight(p->numa_group->active_nodes) > 1)) { | |
2c8a50aa MG |
1477 | for_each_online_node(nid) { |
1478 | if (nid == env.src_nid || nid == p->numa_preferred_nid) | |
1479 | continue; | |
58d081b5 | 1480 | |
7bd95320 | 1481 | dist = node_distance(env.src_nid, env.dst_nid); |
6c6b1193 RR |
1482 | if (sched_numa_topology_type == NUMA_BACKPLANE && |
1483 | dist != env.dist) { | |
1484 | taskweight = task_weight(p, env.src_nid, dist); | |
1485 | groupweight = group_weight(p, env.src_nid, dist); | |
1486 | } | |
7bd95320 | 1487 | |
83e1d2cd | 1488 | /* Only consider nodes where both task and groups benefit */ |
7bd95320 RR |
1489 | taskimp = task_weight(p, nid, dist) - taskweight; |
1490 | groupimp = group_weight(p, nid, dist) - groupweight; | |
887c290e | 1491 | if (taskimp < 0 && groupimp < 0) |
fb13c7ee MG |
1492 | continue; |
1493 | ||
7bd95320 | 1494 | env.dist = dist; |
2c8a50aa MG |
1495 | env.dst_nid = nid; |
1496 | update_numa_stats(&env.dst_stats, env.dst_nid); | |
887c290e | 1497 | task_numa_find_cpu(&env, taskimp, groupimp); |
58d081b5 MG |
1498 | } |
1499 | } | |
1500 | ||
68d1b02a RR |
1501 | /* |
1502 | * If the task is part of a workload that spans multiple NUMA nodes, | |
1503 | * and is migrating into one of the workload's active nodes, remember | |
1504 | * this node as the task's preferred numa node, so the workload can | |
1505 | * settle down. | |
1506 | * A task that migrated to a second choice node will be better off | |
1507 | * trying for a better one later. Do not set the preferred node here. | |
1508 | */ | |
db015dae RR |
1509 | if (p->numa_group) { |
1510 | if (env.best_cpu == -1) | |
1511 | nid = env.src_nid; | |
1512 | else | |
1513 | nid = env.dst_nid; | |
1514 | ||
1515 | if (node_isset(nid, p->numa_group->active_nodes)) | |
1516 | sched_setnuma(p, env.dst_nid); | |
1517 | } | |
1518 | ||
1519 | /* No better CPU than the current one was found. */ | |
1520 | if (env.best_cpu == -1) | |
1521 | return -EAGAIN; | |
0ec8aa00 | 1522 | |
04bb2f94 RR |
1523 | /* |
1524 | * Reset the scan period if the task is being rescheduled on an | |
1525 | * alternative node to recheck if the tasks is now properly placed. | |
1526 | */ | |
1527 | p->numa_scan_period = task_scan_min(p); | |
1528 | ||
fb13c7ee | 1529 | if (env.best_task == NULL) { |
286549dc MG |
1530 | ret = migrate_task_to(p, env.best_cpu); |
1531 | if (ret != 0) | |
1532 | trace_sched_stick_numa(p, env.src_cpu, env.best_cpu); | |
fb13c7ee MG |
1533 | return ret; |
1534 | } | |
1535 | ||
1536 | ret = migrate_swap(p, env.best_task); | |
286549dc MG |
1537 | if (ret != 0) |
1538 | trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task)); | |
fb13c7ee MG |
1539 | put_task_struct(env.best_task); |
1540 | return ret; | |
e6628d5b MG |
1541 | } |
1542 | ||
6b9a7460 MG |
1543 | /* Attempt to migrate a task to a CPU on the preferred node. */ |
1544 | static void numa_migrate_preferred(struct task_struct *p) | |
1545 | { | |
5085e2a3 RR |
1546 | unsigned long interval = HZ; |
1547 | ||
2739d3ee | 1548 | /* This task has no NUMA fault statistics yet */ |
44dba3d5 | 1549 | if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults)) |
6b9a7460 MG |
1550 | return; |
1551 | ||
2739d3ee | 1552 | /* Periodically retry migrating the task to the preferred node */ |
5085e2a3 RR |
1553 | interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16); |
1554 | p->numa_migrate_retry = jiffies + interval; | |
2739d3ee RR |
1555 | |
1556 | /* Success if task is already running on preferred CPU */ | |
de1b301a | 1557 | if (task_node(p) == p->numa_preferred_nid) |
6b9a7460 MG |
1558 | return; |
1559 | ||
1560 | /* Otherwise, try migrate to a CPU on the preferred node */ | |
2739d3ee | 1561 | task_numa_migrate(p); |
6b9a7460 MG |
1562 | } |
1563 | ||
20e07dea RR |
1564 | /* |
1565 | * Find the nodes on which the workload is actively running. We do this by | |
1566 | * tracking the nodes from which NUMA hinting faults are triggered. This can | |
1567 | * be different from the set of nodes where the workload's memory is currently | |
1568 | * located. | |
1569 | * | |
1570 | * The bitmask is used to make smarter decisions on when to do NUMA page | |
1571 | * migrations, To prevent flip-flopping, and excessive page migrations, nodes | |
1572 | * are added when they cause over 6/16 of the maximum number of faults, but | |
1573 | * only removed when they drop below 3/16. | |
1574 | */ | |
1575 | static void update_numa_active_node_mask(struct numa_group *numa_group) | |
1576 | { | |
1577 | unsigned long faults, max_faults = 0; | |
1578 | int nid; | |
1579 | ||
1580 | for_each_online_node(nid) { | |
1581 | faults = group_faults_cpu(numa_group, nid); | |
1582 | if (faults > max_faults) | |
1583 | max_faults = faults; | |
1584 | } | |
1585 | ||
1586 | for_each_online_node(nid) { | |
1587 | faults = group_faults_cpu(numa_group, nid); | |
1588 | if (!node_isset(nid, numa_group->active_nodes)) { | |
1589 | if (faults > max_faults * 6 / 16) | |
1590 | node_set(nid, numa_group->active_nodes); | |
1591 | } else if (faults < max_faults * 3 / 16) | |
1592 | node_clear(nid, numa_group->active_nodes); | |
1593 | } | |
1594 | } | |
1595 | ||
04bb2f94 RR |
1596 | /* |
1597 | * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS | |
1598 | * increments. The more local the fault statistics are, the higher the scan | |
a22b4b01 RR |
1599 | * period will be for the next scan window. If local/(local+remote) ratio is |
1600 | * below NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS) | |
1601 | * the scan period will decrease. Aim for 70% local accesses. | |
04bb2f94 RR |
1602 | */ |
1603 | #define NUMA_PERIOD_SLOTS 10 | |
a22b4b01 | 1604 | #define NUMA_PERIOD_THRESHOLD 7 |
04bb2f94 RR |
1605 | |
1606 | /* | |
1607 | * Increase the scan period (slow down scanning) if the majority of | |
1608 | * our memory is already on our local node, or if the majority of | |
1609 | * the page accesses are shared with other processes. | |
1610 | * Otherwise, decrease the scan period. | |
1611 | */ | |
1612 | static void update_task_scan_period(struct task_struct *p, | |
1613 | unsigned long shared, unsigned long private) | |
1614 | { | |
1615 | unsigned int period_slot; | |
1616 | int ratio; | |
1617 | int diff; | |
1618 | ||
1619 | unsigned long remote = p->numa_faults_locality[0]; | |
1620 | unsigned long local = p->numa_faults_locality[1]; | |
1621 | ||
1622 | /* | |
1623 | * If there were no record hinting faults then either the task is | |
1624 | * completely idle or all activity is areas that are not of interest | |
1625 | * to automatic numa balancing. Scan slower | |
1626 | */ | |
1627 | if (local + shared == 0) { | |
1628 | p->numa_scan_period = min(p->numa_scan_period_max, | |
1629 | p->numa_scan_period << 1); | |
1630 | ||
1631 | p->mm->numa_next_scan = jiffies + | |
1632 | msecs_to_jiffies(p->numa_scan_period); | |
1633 | ||
1634 | return; | |
1635 | } | |
1636 | ||
1637 | /* | |
1638 | * Prepare to scale scan period relative to the current period. | |
1639 | * == NUMA_PERIOD_THRESHOLD scan period stays the same | |
1640 | * < NUMA_PERIOD_THRESHOLD scan period decreases (scan faster) | |
1641 | * >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower) | |
1642 | */ | |
1643 | period_slot = DIV_ROUND_UP(p->numa_scan_period, NUMA_PERIOD_SLOTS); | |
1644 | ratio = (local * NUMA_PERIOD_SLOTS) / (local + remote); | |
1645 | if (ratio >= NUMA_PERIOD_THRESHOLD) { | |
1646 | int slot = ratio - NUMA_PERIOD_THRESHOLD; | |
1647 | if (!slot) | |
1648 | slot = 1; | |
1649 | diff = slot * period_slot; | |
1650 | } else { | |
1651 | diff = -(NUMA_PERIOD_THRESHOLD - ratio) * period_slot; | |
1652 | ||
1653 | /* | |
1654 | * Scale scan rate increases based on sharing. There is an | |
1655 | * inverse relationship between the degree of sharing and | |
1656 | * the adjustment made to the scanning period. Broadly | |
1657 | * speaking the intent is that there is little point | |
1658 | * scanning faster if shared accesses dominate as it may | |
1659 | * simply bounce migrations uselessly | |
1660 | */ | |
2847c90e | 1661 | ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + shared + 1)); |
04bb2f94 RR |
1662 | diff = (diff * ratio) / NUMA_PERIOD_SLOTS; |
1663 | } | |
1664 | ||
1665 | p->numa_scan_period = clamp(p->numa_scan_period + diff, | |
1666 | task_scan_min(p), task_scan_max(p)); | |
1667 | memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); | |
1668 | } | |
1669 | ||
7e2703e6 RR |
1670 | /* |
1671 | * Get the fraction of time the task has been running since the last | |
1672 | * NUMA placement cycle. The scheduler keeps similar statistics, but | |
1673 | * decays those on a 32ms period, which is orders of magnitude off | |
1674 | * from the dozens-of-seconds NUMA balancing period. Use the scheduler | |
1675 | * stats only if the task is so new there are no NUMA statistics yet. | |
1676 | */ | |
1677 | static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period) | |
1678 | { | |
1679 | u64 runtime, delta, now; | |
1680 | /* Use the start of this time slice to avoid calculations. */ | |
1681 | now = p->se.exec_start; | |
1682 | runtime = p->se.sum_exec_runtime; | |
1683 | ||
1684 | if (p->last_task_numa_placement) { | |
1685 | delta = runtime - p->last_sum_exec_runtime; | |
1686 | *period = now - p->last_task_numa_placement; | |
1687 | } else { | |
1688 | delta = p->se.avg.runnable_avg_sum; | |
36ee28e4 | 1689 | *period = p->se.avg.avg_period; |
7e2703e6 RR |
1690 | } |
1691 | ||
1692 | p->last_sum_exec_runtime = runtime; | |
1693 | p->last_task_numa_placement = now; | |
1694 | ||
1695 | return delta; | |
1696 | } | |
1697 | ||
54009416 RR |
1698 | /* |
1699 | * Determine the preferred nid for a task in a numa_group. This needs to | |
1700 | * be done in a way that produces consistent results with group_weight, | |
1701 | * otherwise workloads might not converge. | |
1702 | */ | |
1703 | static int preferred_group_nid(struct task_struct *p, int nid) | |
1704 | { | |
1705 | nodemask_t nodes; | |
1706 | int dist; | |
1707 | ||
1708 | /* Direct connections between all NUMA nodes. */ | |
1709 | if (sched_numa_topology_type == NUMA_DIRECT) | |
1710 | return nid; | |
1711 | ||
1712 | /* | |
1713 | * On a system with glueless mesh NUMA topology, group_weight | |
1714 | * scores nodes according to the number of NUMA hinting faults on | |
1715 | * both the node itself, and on nearby nodes. | |
1716 | */ | |
1717 | if (sched_numa_topology_type == NUMA_GLUELESS_MESH) { | |
1718 | unsigned long score, max_score = 0; | |
1719 | int node, max_node = nid; | |
1720 | ||
1721 | dist = sched_max_numa_distance; | |
1722 | ||
1723 | for_each_online_node(node) { | |
1724 | score = group_weight(p, node, dist); | |
1725 | if (score > max_score) { | |
1726 | max_score = score; | |
1727 | max_node = node; | |
1728 | } | |
1729 | } | |
1730 | return max_node; | |
1731 | } | |
1732 | ||
1733 | /* | |
1734 | * Finding the preferred nid in a system with NUMA backplane | |
1735 | * interconnect topology is more involved. The goal is to locate | |
1736 | * tasks from numa_groups near each other in the system, and | |
1737 | * untangle workloads from different sides of the system. This requires | |
1738 | * searching down the hierarchy of node groups, recursively searching | |
1739 | * inside the highest scoring group of nodes. The nodemask tricks | |
1740 | * keep the complexity of the search down. | |
1741 | */ | |
1742 | nodes = node_online_map; | |
1743 | for (dist = sched_max_numa_distance; dist > LOCAL_DISTANCE; dist--) { | |
1744 | unsigned long max_faults = 0; | |
81907478 | 1745 | nodemask_t max_group = NODE_MASK_NONE; |
54009416 RR |
1746 | int a, b; |
1747 | ||
1748 | /* Are there nodes at this distance from each other? */ | |
1749 | if (!find_numa_distance(dist)) | |
1750 | continue; | |
1751 | ||
1752 | for_each_node_mask(a, nodes) { | |
1753 | unsigned long faults = 0; | |
1754 | nodemask_t this_group; | |
1755 | nodes_clear(this_group); | |
1756 | ||
1757 | /* Sum group's NUMA faults; includes a==b case. */ | |
1758 | for_each_node_mask(b, nodes) { | |
1759 | if (node_distance(a, b) < dist) { | |
1760 | faults += group_faults(p, b); | |
1761 | node_set(b, this_group); | |
1762 | node_clear(b, nodes); | |
1763 | } | |
1764 | } | |
1765 | ||
1766 | /* Remember the top group. */ | |
1767 | if (faults > max_faults) { | |
1768 | max_faults = faults; | |
1769 | max_group = this_group; | |
1770 | /* | |
1771 | * subtle: at the smallest distance there is | |
1772 | * just one node left in each "group", the | |
1773 | * winner is the preferred nid. | |
1774 | */ | |
1775 | nid = a; | |
1776 | } | |
1777 | } | |
1778 | /* Next round, evaluate the nodes within max_group. */ | |
890a5409 JB |
1779 | if (!max_faults) |
1780 | break; | |
54009416 RR |
1781 | nodes = max_group; |
1782 | } | |
1783 | return nid; | |
1784 | } | |
1785 | ||
cbee9f88 PZ |
1786 | static void task_numa_placement(struct task_struct *p) |
1787 | { | |
83e1d2cd MG |
1788 | int seq, nid, max_nid = -1, max_group_nid = -1; |
1789 | unsigned long max_faults = 0, max_group_faults = 0; | |
04bb2f94 | 1790 | unsigned long fault_types[2] = { 0, 0 }; |
7e2703e6 RR |
1791 | unsigned long total_faults; |
1792 | u64 runtime, period; | |
7dbd13ed | 1793 | spinlock_t *group_lock = NULL; |
cbee9f88 | 1794 | |
2832bc19 | 1795 | seq = ACCESS_ONCE(p->mm->numa_scan_seq); |
cbee9f88 PZ |
1796 | if (p->numa_scan_seq == seq) |
1797 | return; | |
1798 | p->numa_scan_seq = seq; | |
598f0ec0 | 1799 | p->numa_scan_period_max = task_scan_max(p); |
cbee9f88 | 1800 | |
7e2703e6 RR |
1801 | total_faults = p->numa_faults_locality[0] + |
1802 | p->numa_faults_locality[1]; | |
1803 | runtime = numa_get_avg_runtime(p, &period); | |
1804 | ||
7dbd13ed MG |
1805 | /* If the task is part of a group prevent parallel updates to group stats */ |
1806 | if (p->numa_group) { | |
1807 | group_lock = &p->numa_group->lock; | |
60e69eed | 1808 | spin_lock_irq(group_lock); |
7dbd13ed MG |
1809 | } |
1810 | ||
688b7585 MG |
1811 | /* Find the node with the highest number of faults */ |
1812 | for_each_online_node(nid) { | |
44dba3d5 IM |
1813 | /* Keep track of the offsets in numa_faults array */ |
1814 | int mem_idx, membuf_idx, cpu_idx, cpubuf_idx; | |
83e1d2cd | 1815 | unsigned long faults = 0, group_faults = 0; |
44dba3d5 | 1816 | int priv; |
745d6147 | 1817 | |
be1e4e76 | 1818 | for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) { |
7e2703e6 | 1819 | long diff, f_diff, f_weight; |
8c8a743c | 1820 | |
44dba3d5 IM |
1821 | mem_idx = task_faults_idx(NUMA_MEM, nid, priv); |
1822 | membuf_idx = task_faults_idx(NUMA_MEMBUF, nid, priv); | |
1823 | cpu_idx = task_faults_idx(NUMA_CPU, nid, priv); | |
1824 | cpubuf_idx = task_faults_idx(NUMA_CPUBUF, nid, priv); | |
745d6147 | 1825 | |
ac8e895b | 1826 | /* Decay existing window, copy faults since last scan */ |
44dba3d5 IM |
1827 | diff = p->numa_faults[membuf_idx] - p->numa_faults[mem_idx] / 2; |
1828 | fault_types[priv] += p->numa_faults[membuf_idx]; | |
1829 | p->numa_faults[membuf_idx] = 0; | |
fb13c7ee | 1830 | |
7e2703e6 RR |
1831 | /* |
1832 | * Normalize the faults_from, so all tasks in a group | |
1833 | * count according to CPU use, instead of by the raw | |
1834 | * number of faults. Tasks with little runtime have | |
1835 | * little over-all impact on throughput, and thus their | |
1836 | * faults are less important. | |
1837 | */ | |
1838 | f_weight = div64_u64(runtime << 16, period + 1); | |
44dba3d5 | 1839 | f_weight = (f_weight * p->numa_faults[cpubuf_idx]) / |
7e2703e6 | 1840 | (total_faults + 1); |
44dba3d5 IM |
1841 | f_diff = f_weight - p->numa_faults[cpu_idx] / 2; |
1842 | p->numa_faults[cpubuf_idx] = 0; | |
50ec8a40 | 1843 | |
44dba3d5 IM |
1844 | p->numa_faults[mem_idx] += diff; |
1845 | p->numa_faults[cpu_idx] += f_diff; | |
1846 | faults += p->numa_faults[mem_idx]; | |
83e1d2cd | 1847 | p->total_numa_faults += diff; |
8c8a743c | 1848 | if (p->numa_group) { |
44dba3d5 IM |
1849 | /* |
1850 | * safe because we can only change our own group | |
1851 | * | |
1852 | * mem_idx represents the offset for a given | |
1853 | * nid and priv in a specific region because it | |
1854 | * is at the beginning of the numa_faults array. | |
1855 | */ | |
1856 | p->numa_group->faults[mem_idx] += diff; | |
1857 | p->numa_group->faults_cpu[mem_idx] += f_diff; | |
989348b5 | 1858 | p->numa_group->total_faults += diff; |
44dba3d5 | 1859 | group_faults += p->numa_group->faults[mem_idx]; |
8c8a743c | 1860 | } |
ac8e895b MG |
1861 | } |
1862 | ||
688b7585 MG |
1863 | if (faults > max_faults) { |
1864 | max_faults = faults; | |
1865 | max_nid = nid; | |
1866 | } | |
83e1d2cd MG |
1867 | |
1868 | if (group_faults > max_group_faults) { | |
1869 | max_group_faults = group_faults; | |
1870 | max_group_nid = nid; | |
1871 | } | |
1872 | } | |
1873 | ||
04bb2f94 RR |
1874 | update_task_scan_period(p, fault_types[0], fault_types[1]); |
1875 | ||
7dbd13ed | 1876 | if (p->numa_group) { |
20e07dea | 1877 | update_numa_active_node_mask(p->numa_group); |
60e69eed | 1878 | spin_unlock_irq(group_lock); |
54009416 | 1879 | max_nid = preferred_group_nid(p, max_group_nid); |
688b7585 MG |
1880 | } |
1881 | ||
bb97fc31 RR |
1882 | if (max_faults) { |
1883 | /* Set the new preferred node */ | |
1884 | if (max_nid != p->numa_preferred_nid) | |
1885 | sched_setnuma(p, max_nid); | |
1886 | ||
1887 | if (task_node(p) != p->numa_preferred_nid) | |
1888 | numa_migrate_preferred(p); | |
3a7053b3 | 1889 | } |
cbee9f88 PZ |
1890 | } |
1891 | ||
8c8a743c PZ |
1892 | static inline int get_numa_group(struct numa_group *grp) |
1893 | { | |
1894 | return atomic_inc_not_zero(&grp->refcount); | |
1895 | } | |
1896 | ||
1897 | static inline void put_numa_group(struct numa_group *grp) | |
1898 | { | |
1899 | if (atomic_dec_and_test(&grp->refcount)) | |
1900 | kfree_rcu(grp, rcu); | |
1901 | } | |
1902 | ||
3e6a9418 MG |
1903 | static void task_numa_group(struct task_struct *p, int cpupid, int flags, |
1904 | int *priv) | |
8c8a743c PZ |
1905 | { |
1906 | struct numa_group *grp, *my_grp; | |
1907 | struct task_struct *tsk; | |
1908 | bool join = false; | |
1909 | int cpu = cpupid_to_cpu(cpupid); | |
1910 | int i; | |
1911 | ||
1912 | if (unlikely(!p->numa_group)) { | |
1913 | unsigned int size = sizeof(struct numa_group) + | |
50ec8a40 | 1914 | 4*nr_node_ids*sizeof(unsigned long); |
8c8a743c PZ |
1915 | |
1916 | grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); | |
1917 | if (!grp) | |
1918 | return; | |
1919 | ||
1920 | atomic_set(&grp->refcount, 1); | |
1921 | spin_lock_init(&grp->lock); | |
e29cf08b | 1922 | grp->gid = p->pid; |
50ec8a40 | 1923 | /* Second half of the array tracks nids where faults happen */ |
be1e4e76 RR |
1924 | grp->faults_cpu = grp->faults + NR_NUMA_HINT_FAULT_TYPES * |
1925 | nr_node_ids; | |
8c8a743c | 1926 | |
20e07dea RR |
1927 | node_set(task_node(current), grp->active_nodes); |
1928 | ||
be1e4e76 | 1929 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) |
44dba3d5 | 1930 | grp->faults[i] = p->numa_faults[i]; |
8c8a743c | 1931 | |
989348b5 | 1932 | grp->total_faults = p->total_numa_faults; |
83e1d2cd | 1933 | |
8c8a743c PZ |
1934 | grp->nr_tasks++; |
1935 | rcu_assign_pointer(p->numa_group, grp); | |
1936 | } | |
1937 | ||
1938 | rcu_read_lock(); | |
1939 | tsk = ACCESS_ONCE(cpu_rq(cpu)->curr); | |
1940 | ||
1941 | if (!cpupid_match_pid(tsk, cpupid)) | |
3354781a | 1942 | goto no_join; |
8c8a743c PZ |
1943 | |
1944 | grp = rcu_dereference(tsk->numa_group); | |
1945 | if (!grp) | |
3354781a | 1946 | goto no_join; |
8c8a743c PZ |
1947 | |
1948 | my_grp = p->numa_group; | |
1949 | if (grp == my_grp) | |
3354781a | 1950 | goto no_join; |
8c8a743c PZ |
1951 | |
1952 | /* | |
1953 | * Only join the other group if its bigger; if we're the bigger group, | |
1954 | * the other task will join us. | |
1955 | */ | |
1956 | if (my_grp->nr_tasks > grp->nr_tasks) | |
3354781a | 1957 | goto no_join; |
8c8a743c PZ |
1958 | |
1959 | /* | |
1960 | * Tie-break on the grp address. | |
1961 | */ | |
1962 | if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp) | |
3354781a | 1963 | goto no_join; |
8c8a743c | 1964 | |
dabe1d99 RR |
1965 | /* Always join threads in the same process. */ |
1966 | if (tsk->mm == current->mm) | |
1967 | join = true; | |
1968 | ||
1969 | /* Simple filter to avoid false positives due to PID collisions */ | |
1970 | if (flags & TNF_SHARED) | |
1971 | join = true; | |
8c8a743c | 1972 | |
3e6a9418 MG |
1973 | /* Update priv based on whether false sharing was detected */ |
1974 | *priv = !join; | |
1975 | ||
dabe1d99 | 1976 | if (join && !get_numa_group(grp)) |
3354781a | 1977 | goto no_join; |
8c8a743c | 1978 | |
8c8a743c PZ |
1979 | rcu_read_unlock(); |
1980 | ||
1981 | if (!join) | |
1982 | return; | |
1983 | ||
60e69eed MG |
1984 | BUG_ON(irqs_disabled()); |
1985 | double_lock_irq(&my_grp->lock, &grp->lock); | |
989348b5 | 1986 | |
be1e4e76 | 1987 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) { |
44dba3d5 IM |
1988 | my_grp->faults[i] -= p->numa_faults[i]; |
1989 | grp->faults[i] += p->numa_faults[i]; | |
8c8a743c | 1990 | } |
989348b5 MG |
1991 | my_grp->total_faults -= p->total_numa_faults; |
1992 | grp->total_faults += p->total_numa_faults; | |
8c8a743c | 1993 | |
8c8a743c PZ |
1994 | my_grp->nr_tasks--; |
1995 | grp->nr_tasks++; | |
1996 | ||
1997 | spin_unlock(&my_grp->lock); | |
60e69eed | 1998 | spin_unlock_irq(&grp->lock); |
8c8a743c PZ |
1999 | |
2000 | rcu_assign_pointer(p->numa_group, grp); | |
2001 | ||
2002 | put_numa_group(my_grp); | |
3354781a PZ |
2003 | return; |
2004 | ||
2005 | no_join: | |
2006 | rcu_read_unlock(); | |
2007 | return; | |
8c8a743c PZ |
2008 | } |
2009 | ||
2010 | void task_numa_free(struct task_struct *p) | |
2011 | { | |
2012 | struct numa_group *grp = p->numa_group; | |
44dba3d5 | 2013 | void *numa_faults = p->numa_faults; |
e9dd685c SR |
2014 | unsigned long flags; |
2015 | int i; | |
8c8a743c PZ |
2016 | |
2017 | if (grp) { | |
e9dd685c | 2018 | spin_lock_irqsave(&grp->lock, flags); |
be1e4e76 | 2019 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) |
44dba3d5 | 2020 | grp->faults[i] -= p->numa_faults[i]; |
989348b5 | 2021 | grp->total_faults -= p->total_numa_faults; |
83e1d2cd | 2022 | |
8c8a743c | 2023 | grp->nr_tasks--; |
e9dd685c | 2024 | spin_unlock_irqrestore(&grp->lock, flags); |
35b123e2 | 2025 | RCU_INIT_POINTER(p->numa_group, NULL); |
8c8a743c PZ |
2026 | put_numa_group(grp); |
2027 | } | |
2028 | ||
44dba3d5 | 2029 | p->numa_faults = NULL; |
82727018 | 2030 | kfree(numa_faults); |
8c8a743c PZ |
2031 | } |
2032 | ||
cbee9f88 PZ |
2033 | /* |
2034 | * Got a PROT_NONE fault for a page on @node. | |
2035 | */ | |
58b46da3 | 2036 | void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags) |
cbee9f88 PZ |
2037 | { |
2038 | struct task_struct *p = current; | |
6688cc05 | 2039 | bool migrated = flags & TNF_MIGRATED; |
58b46da3 | 2040 | int cpu_node = task_node(current); |
792568ec | 2041 | int local = !!(flags & TNF_FAULT_LOCAL); |
ac8e895b | 2042 | int priv; |
cbee9f88 | 2043 | |
10e84b97 | 2044 | if (!numabalancing_enabled) |
1a687c2e MG |
2045 | return; |
2046 | ||
9ff1d9ff MG |
2047 | /* for example, ksmd faulting in a user's mm */ |
2048 | if (!p->mm) | |
2049 | return; | |
2050 | ||
f809ca9a | 2051 | /* Allocate buffer to track faults on a per-node basis */ |
44dba3d5 IM |
2052 | if (unlikely(!p->numa_faults)) { |
2053 | int size = sizeof(*p->numa_faults) * | |
be1e4e76 | 2054 | NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids; |
f809ca9a | 2055 | |
44dba3d5 IM |
2056 | p->numa_faults = kzalloc(size, GFP_KERNEL|__GFP_NOWARN); |
2057 | if (!p->numa_faults) | |
f809ca9a | 2058 | return; |
745d6147 | 2059 | |
83e1d2cd | 2060 | p->total_numa_faults = 0; |
04bb2f94 | 2061 | memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); |
f809ca9a | 2062 | } |
cbee9f88 | 2063 | |
8c8a743c PZ |
2064 | /* |
2065 | * First accesses are treated as private, otherwise consider accesses | |
2066 | * to be private if the accessing pid has not changed | |
2067 | */ | |
2068 | if (unlikely(last_cpupid == (-1 & LAST_CPUPID_MASK))) { | |
2069 | priv = 1; | |
2070 | } else { | |
2071 | priv = cpupid_match_pid(p, last_cpupid); | |
6688cc05 | 2072 | if (!priv && !(flags & TNF_NO_GROUP)) |
3e6a9418 | 2073 | task_numa_group(p, last_cpupid, flags, &priv); |
8c8a743c PZ |
2074 | } |
2075 | ||
792568ec RR |
2076 | /* |
2077 | * If a workload spans multiple NUMA nodes, a shared fault that | |
2078 | * occurs wholly within the set of nodes that the workload is | |
2079 | * actively using should be counted as local. This allows the | |
2080 | * scan rate to slow down when a workload has settled down. | |
2081 | */ | |
2082 | if (!priv && !local && p->numa_group && | |
2083 | node_isset(cpu_node, p->numa_group->active_nodes) && | |
2084 | node_isset(mem_node, p->numa_group->active_nodes)) | |
2085 | local = 1; | |
2086 | ||
cbee9f88 | 2087 | task_numa_placement(p); |
f809ca9a | 2088 | |
2739d3ee RR |
2089 | /* |
2090 | * Retry task to preferred node migration periodically, in case it | |
2091 | * case it previously failed, or the scheduler moved us. | |
2092 | */ | |
2093 | if (time_after(jiffies, p->numa_migrate_retry)) | |
6b9a7460 MG |
2094 | numa_migrate_preferred(p); |
2095 | ||
b32e86b4 IM |
2096 | if (migrated) |
2097 | p->numa_pages_migrated += pages; | |
2098 | ||
44dba3d5 IM |
2099 | p->numa_faults[task_faults_idx(NUMA_MEMBUF, mem_node, priv)] += pages; |
2100 | p->numa_faults[task_faults_idx(NUMA_CPUBUF, cpu_node, priv)] += pages; | |
792568ec | 2101 | p->numa_faults_locality[local] += pages; |
cbee9f88 PZ |
2102 | } |
2103 | ||
6e5fb223 PZ |
2104 | static void reset_ptenuma_scan(struct task_struct *p) |
2105 | { | |
2106 | ACCESS_ONCE(p->mm->numa_scan_seq)++; | |
2107 | p->mm->numa_scan_offset = 0; | |
2108 | } | |
2109 | ||
cbee9f88 PZ |
2110 | /* |
2111 | * The expensive part of numa migration is done from task_work context. | |
2112 | * Triggered from task_tick_numa(). | |
2113 | */ | |
2114 | void task_numa_work(struct callback_head *work) | |
2115 | { | |
2116 | unsigned long migrate, next_scan, now = jiffies; | |
2117 | struct task_struct *p = current; | |
2118 | struct mm_struct *mm = p->mm; | |
6e5fb223 | 2119 | struct vm_area_struct *vma; |
9f40604c | 2120 | unsigned long start, end; |
598f0ec0 | 2121 | unsigned long nr_pte_updates = 0; |
9f40604c | 2122 | long pages; |
cbee9f88 PZ |
2123 | |
2124 | WARN_ON_ONCE(p != container_of(work, struct task_struct, numa_work)); | |
2125 | ||
2126 | work->next = work; /* protect against double add */ | |
2127 | /* | |
2128 | * Who cares about NUMA placement when they're dying. | |
2129 | * | |
2130 | * NOTE: make sure not to dereference p->mm before this check, | |
2131 | * exit_task_work() happens _after_ exit_mm() so we could be called | |
2132 | * without p->mm even though we still had it when we enqueued this | |
2133 | * work. | |
2134 | */ | |
2135 | if (p->flags & PF_EXITING) | |
2136 | return; | |
2137 | ||
930aa174 | 2138 | if (!mm->numa_next_scan) { |
7e8d16b6 MG |
2139 | mm->numa_next_scan = now + |
2140 | msecs_to_jiffies(sysctl_numa_balancing_scan_delay); | |
b8593bfd MG |
2141 | } |
2142 | ||
cbee9f88 PZ |
2143 | /* |
2144 | * Enforce maximal scan/migration frequency.. | |
2145 | */ | |
2146 | migrate = mm->numa_next_scan; | |
2147 | if (time_before(now, migrate)) | |
2148 | return; | |
2149 | ||
598f0ec0 MG |
2150 | if (p->numa_scan_period == 0) { |
2151 | p->numa_scan_period_max = task_scan_max(p); | |
2152 | p->numa_scan_period = task_scan_min(p); | |
2153 | } | |
cbee9f88 | 2154 | |
fb003b80 | 2155 | next_scan = now + msecs_to_jiffies(p->numa_scan_period); |
cbee9f88 PZ |
2156 | if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate) |
2157 | return; | |
2158 | ||
19a78d11 PZ |
2159 | /* |
2160 | * Delay this task enough that another task of this mm will likely win | |
2161 | * the next time around. | |
2162 | */ | |
2163 | p->node_stamp += 2 * TICK_NSEC; | |
2164 | ||
9f40604c MG |
2165 | start = mm->numa_scan_offset; |
2166 | pages = sysctl_numa_balancing_scan_size; | |
2167 | pages <<= 20 - PAGE_SHIFT; /* MB in pages */ | |
2168 | if (!pages) | |
2169 | return; | |
cbee9f88 | 2170 | |
6e5fb223 | 2171 | down_read(&mm->mmap_sem); |
9f40604c | 2172 | vma = find_vma(mm, start); |
6e5fb223 PZ |
2173 | if (!vma) { |
2174 | reset_ptenuma_scan(p); | |
9f40604c | 2175 | start = 0; |
6e5fb223 PZ |
2176 | vma = mm->mmap; |
2177 | } | |
9f40604c | 2178 | for (; vma; vma = vma->vm_next) { |
6b6482bb | 2179 | if (!vma_migratable(vma) || !vma_policy_mof(vma)) |
6e5fb223 PZ |
2180 | continue; |
2181 | ||
4591ce4f MG |
2182 | /* |
2183 | * Shared library pages mapped by multiple processes are not | |
2184 | * migrated as it is expected they are cache replicated. Avoid | |
2185 | * hinting faults in read-only file-backed mappings or the vdso | |
2186 | * as migrating the pages will be of marginal benefit. | |
2187 | */ | |
2188 | if (!vma->vm_mm || | |
2189 | (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ))) | |
2190 | continue; | |
2191 | ||
3c67f474 MG |
2192 | /* |
2193 | * Skip inaccessible VMAs to avoid any confusion between | |
2194 | * PROT_NONE and NUMA hinting ptes | |
2195 | */ | |
2196 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) | |
2197 | continue; | |
4591ce4f | 2198 | |
9f40604c MG |
2199 | do { |
2200 | start = max(start, vma->vm_start); | |
2201 | end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE); | |
2202 | end = min(end, vma->vm_end); | |
598f0ec0 MG |
2203 | nr_pte_updates += change_prot_numa(vma, start, end); |
2204 | ||
2205 | /* | |
2206 | * Scan sysctl_numa_balancing_scan_size but ensure that | |
2207 | * at least one PTE is updated so that unused virtual | |
2208 | * address space is quickly skipped. | |
2209 | */ | |
2210 | if (nr_pte_updates) | |
2211 | pages -= (end - start) >> PAGE_SHIFT; | |
6e5fb223 | 2212 | |
9f40604c MG |
2213 | start = end; |
2214 | if (pages <= 0) | |
2215 | goto out; | |
3cf1962c RR |
2216 | |
2217 | cond_resched(); | |
9f40604c | 2218 | } while (end != vma->vm_end); |
cbee9f88 | 2219 | } |
6e5fb223 | 2220 | |
9f40604c | 2221 | out: |
6e5fb223 | 2222 | /* |
c69307d5 PZ |
2223 | * It is possible to reach the end of the VMA list but the last few |
2224 | * VMAs are not guaranteed to the vma_migratable. If they are not, we | |
2225 | * would find the !migratable VMA on the next scan but not reset the | |
2226 | * scanner to the start so check it now. | |
6e5fb223 PZ |
2227 | */ |
2228 | if (vma) | |
9f40604c | 2229 | mm->numa_scan_offset = start; |
6e5fb223 PZ |
2230 | else |
2231 | reset_ptenuma_scan(p); | |
2232 | up_read(&mm->mmap_sem); | |
cbee9f88 PZ |
2233 | } |
2234 | ||
2235 | /* | |
2236 | * Drive the periodic memory faults.. | |
2237 | */ | |
2238 | void task_tick_numa(struct rq *rq, struct task_struct *curr) | |
2239 | { | |
2240 | struct callback_head *work = &curr->numa_work; | |
2241 | u64 period, now; | |
2242 | ||
2243 | /* | |
2244 | * We don't care about NUMA placement if we don't have memory. | |
2245 | */ | |
2246 | if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work) | |
2247 | return; | |
2248 | ||
2249 | /* | |
2250 | * Using runtime rather than walltime has the dual advantage that | |
2251 | * we (mostly) drive the selection from busy threads and that the | |
2252 | * task needs to have done some actual work before we bother with | |
2253 | * NUMA placement. | |
2254 | */ | |
2255 | now = curr->se.sum_exec_runtime; | |
2256 | period = (u64)curr->numa_scan_period * NSEC_PER_MSEC; | |
2257 | ||
2258 | if (now - curr->node_stamp > period) { | |
4b96a29b | 2259 | if (!curr->node_stamp) |
598f0ec0 | 2260 | curr->numa_scan_period = task_scan_min(curr); |
19a78d11 | 2261 | curr->node_stamp += period; |
cbee9f88 PZ |
2262 | |
2263 | if (!time_before(jiffies, curr->mm->numa_next_scan)) { | |
2264 | init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */ | |
2265 | task_work_add(curr, work, true); | |
2266 | } | |
2267 | } | |
2268 | } | |
2269 | #else | |
2270 | static void task_tick_numa(struct rq *rq, struct task_struct *curr) | |
2271 | { | |
2272 | } | |
0ec8aa00 PZ |
2273 | |
2274 | static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p) | |
2275 | { | |
2276 | } | |
2277 | ||
2278 | static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p) | |
2279 | { | |
2280 | } | |
cbee9f88 PZ |
2281 | #endif /* CONFIG_NUMA_BALANCING */ |
2282 | ||
30cfdcfc DA |
2283 | static void |
2284 | account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2285 | { | |
2286 | update_load_add(&cfs_rq->load, se->load.weight); | |
c09595f6 | 2287 | if (!parent_entity(se)) |
029632fb | 2288 | update_load_add(&rq_of(cfs_rq)->load, se->load.weight); |
367456c7 | 2289 | #ifdef CONFIG_SMP |
0ec8aa00 PZ |
2290 | if (entity_is_task(se)) { |
2291 | struct rq *rq = rq_of(cfs_rq); | |
2292 | ||
2293 | account_numa_enqueue(rq, task_of(se)); | |
2294 | list_add(&se->group_node, &rq->cfs_tasks); | |
2295 | } | |
367456c7 | 2296 | #endif |
30cfdcfc | 2297 | cfs_rq->nr_running++; |
30cfdcfc DA |
2298 | } |
2299 | ||
2300 | static void | |
2301 | account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2302 | { | |
2303 | update_load_sub(&cfs_rq->load, se->load.weight); | |
c09595f6 | 2304 | if (!parent_entity(se)) |
029632fb | 2305 | update_load_sub(&rq_of(cfs_rq)->load, se->load.weight); |
0ec8aa00 PZ |
2306 | if (entity_is_task(se)) { |
2307 | account_numa_dequeue(rq_of(cfs_rq), task_of(se)); | |
b87f1724 | 2308 | list_del_init(&se->group_node); |
0ec8aa00 | 2309 | } |
30cfdcfc | 2310 | cfs_rq->nr_running--; |
30cfdcfc DA |
2311 | } |
2312 | ||
3ff6dcac YZ |
2313 | #ifdef CONFIG_FAIR_GROUP_SCHED |
2314 | # ifdef CONFIG_SMP | |
cf5f0acf PZ |
2315 | static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq) |
2316 | { | |
2317 | long tg_weight; | |
2318 | ||
2319 | /* | |
2320 | * Use this CPU's actual weight instead of the last load_contribution | |
2321 | * to gain a more accurate current total weight. See | |
2322 | * update_cfs_rq_load_contribution(). | |
2323 | */ | |
bf5b986e | 2324 | tg_weight = atomic_long_read(&tg->load_avg); |
82958366 | 2325 | tg_weight -= cfs_rq->tg_load_contrib; |
cf5f0acf PZ |
2326 | tg_weight += cfs_rq->load.weight; |
2327 | ||
2328 | return tg_weight; | |
2329 | } | |
2330 | ||
6d5ab293 | 2331 | static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) |
3ff6dcac | 2332 | { |
cf5f0acf | 2333 | long tg_weight, load, shares; |
3ff6dcac | 2334 | |
cf5f0acf | 2335 | tg_weight = calc_tg_weight(tg, cfs_rq); |
6d5ab293 | 2336 | load = cfs_rq->load.weight; |
3ff6dcac | 2337 | |
3ff6dcac | 2338 | shares = (tg->shares * load); |
cf5f0acf PZ |
2339 | if (tg_weight) |
2340 | shares /= tg_weight; | |
3ff6dcac YZ |
2341 | |
2342 | if (shares < MIN_SHARES) | |
2343 | shares = MIN_SHARES; | |
2344 | if (shares > tg->shares) | |
2345 | shares = tg->shares; | |
2346 | ||
2347 | return shares; | |
2348 | } | |
3ff6dcac | 2349 | # else /* CONFIG_SMP */ |
6d5ab293 | 2350 | static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) |
3ff6dcac YZ |
2351 | { |
2352 | return tg->shares; | |
2353 | } | |
3ff6dcac | 2354 | # endif /* CONFIG_SMP */ |
2069dd75 PZ |
2355 | static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, |
2356 | unsigned long weight) | |
2357 | { | |
19e5eebb PT |
2358 | if (se->on_rq) { |
2359 | /* commit outstanding execution time */ | |
2360 | if (cfs_rq->curr == se) | |
2361 | update_curr(cfs_rq); | |
2069dd75 | 2362 | account_entity_dequeue(cfs_rq, se); |
19e5eebb | 2363 | } |
2069dd75 PZ |
2364 | |
2365 | update_load_set(&se->load, weight); | |
2366 | ||
2367 | if (se->on_rq) | |
2368 | account_entity_enqueue(cfs_rq, se); | |
2369 | } | |
2370 | ||
82958366 PT |
2371 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq); |
2372 | ||
6d5ab293 | 2373 | static void update_cfs_shares(struct cfs_rq *cfs_rq) |
2069dd75 PZ |
2374 | { |
2375 | struct task_group *tg; | |
2376 | struct sched_entity *se; | |
3ff6dcac | 2377 | long shares; |
2069dd75 | 2378 | |
2069dd75 PZ |
2379 | tg = cfs_rq->tg; |
2380 | se = tg->se[cpu_of(rq_of(cfs_rq))]; | |
64660c86 | 2381 | if (!se || throttled_hierarchy(cfs_rq)) |
2069dd75 | 2382 | return; |
3ff6dcac YZ |
2383 | #ifndef CONFIG_SMP |
2384 | if (likely(se->load.weight == tg->shares)) | |
2385 | return; | |
2386 | #endif | |
6d5ab293 | 2387 | shares = calc_cfs_shares(cfs_rq, tg); |
2069dd75 PZ |
2388 | |
2389 | reweight_entity(cfs_rq_of(se), se, shares); | |
2390 | } | |
2391 | #else /* CONFIG_FAIR_GROUP_SCHED */ | |
6d5ab293 | 2392 | static inline void update_cfs_shares(struct cfs_rq *cfs_rq) |
2069dd75 PZ |
2393 | { |
2394 | } | |
2395 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
2396 | ||
141965c7 | 2397 | #ifdef CONFIG_SMP |
5b51f2f8 PT |
2398 | /* |
2399 | * We choose a half-life close to 1 scheduling period. | |
2400 | * Note: The tables below are dependent on this value. | |
2401 | */ | |
2402 | #define LOAD_AVG_PERIOD 32 | |
2403 | #define LOAD_AVG_MAX 47742 /* maximum possible load avg */ | |
2404 | #define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_MAX_AVG */ | |
2405 | ||
2406 | /* Precomputed fixed inverse multiplies for multiplication by y^n */ | |
2407 | static const u32 runnable_avg_yN_inv[] = { | |
2408 | 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6, | |
2409 | 0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85, | |
2410 | 0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581, | |
2411 | 0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9, | |
2412 | 0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80, | |
2413 | 0x85aac367, 0x82cd8698, | |
2414 | }; | |
2415 | ||
2416 | /* | |
2417 | * Precomputed \Sum y^k { 1<=k<=n }. These are floor(true_value) to prevent | |
2418 | * over-estimates when re-combining. | |
2419 | */ | |
2420 | static const u32 runnable_avg_yN_sum[] = { | |
2421 | 0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103, | |
2422 | 9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082, | |
2423 | 17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371, | |
2424 | }; | |
2425 | ||
9d85f21c PT |
2426 | /* |
2427 | * Approximate: | |
2428 | * val * y^n, where y^32 ~= 0.5 (~1 scheduling period) | |
2429 | */ | |
2430 | static __always_inline u64 decay_load(u64 val, u64 n) | |
2431 | { | |
5b51f2f8 PT |
2432 | unsigned int local_n; |
2433 | ||
2434 | if (!n) | |
2435 | return val; | |
2436 | else if (unlikely(n > LOAD_AVG_PERIOD * 63)) | |
2437 | return 0; | |
2438 | ||
2439 | /* after bounds checking we can collapse to 32-bit */ | |
2440 | local_n = n; | |
2441 | ||
2442 | /* | |
2443 | * As y^PERIOD = 1/2, we can combine | |
9c58c79a ZZ |
2444 | * y^n = 1/2^(n/PERIOD) * y^(n%PERIOD) |
2445 | * With a look-up table which covers y^n (n<PERIOD) | |
5b51f2f8 PT |
2446 | * |
2447 | * To achieve constant time decay_load. | |
2448 | */ | |
2449 | if (unlikely(local_n >= LOAD_AVG_PERIOD)) { | |
2450 | val >>= local_n / LOAD_AVG_PERIOD; | |
2451 | local_n %= LOAD_AVG_PERIOD; | |
9d85f21c PT |
2452 | } |
2453 | ||
5b51f2f8 PT |
2454 | val *= runnable_avg_yN_inv[local_n]; |
2455 | /* We don't use SRR here since we always want to round down. */ | |
2456 | return val >> 32; | |
2457 | } | |
2458 | ||
2459 | /* | |
2460 | * For updates fully spanning n periods, the contribution to runnable | |
2461 | * average will be: \Sum 1024*y^n | |
2462 | * | |
2463 | * We can compute this reasonably efficiently by combining: | |
2464 | * y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for n <PERIOD} | |
2465 | */ | |
2466 | static u32 __compute_runnable_contrib(u64 n) | |
2467 | { | |
2468 | u32 contrib = 0; | |
2469 | ||
2470 | if (likely(n <= LOAD_AVG_PERIOD)) | |
2471 | return runnable_avg_yN_sum[n]; | |
2472 | else if (unlikely(n >= LOAD_AVG_MAX_N)) | |
2473 | return LOAD_AVG_MAX; | |
2474 | ||
2475 | /* Compute \Sum k^n combining precomputed values for k^i, \Sum k^j */ | |
2476 | do { | |
2477 | contrib /= 2; /* y^LOAD_AVG_PERIOD = 1/2 */ | |
2478 | contrib += runnable_avg_yN_sum[LOAD_AVG_PERIOD]; | |
2479 | ||
2480 | n -= LOAD_AVG_PERIOD; | |
2481 | } while (n > LOAD_AVG_PERIOD); | |
2482 | ||
2483 | contrib = decay_load(contrib, n); | |
2484 | return contrib + runnable_avg_yN_sum[n]; | |
9d85f21c PT |
2485 | } |
2486 | ||
2487 | /* | |
2488 | * We can represent the historical contribution to runnable average as the | |
2489 | * coefficients of a geometric series. To do this we sub-divide our runnable | |
2490 | * history into segments of approximately 1ms (1024us); label the segment that | |
2491 | * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g. | |
2492 | * | |
2493 | * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ... | |
2494 | * p0 p1 p2 | |
2495 | * (now) (~1ms ago) (~2ms ago) | |
2496 | * | |
2497 | * Let u_i denote the fraction of p_i that the entity was runnable. | |
2498 | * | |
2499 | * We then designate the fractions u_i as our co-efficients, yielding the | |
2500 | * following representation of historical load: | |
2501 | * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ... | |
2502 | * | |
2503 | * We choose y based on the with of a reasonably scheduling period, fixing: | |
2504 | * y^32 = 0.5 | |
2505 | * | |
2506 | * This means that the contribution to load ~32ms ago (u_32) will be weighted | |
2507 | * approximately half as much as the contribution to load within the last ms | |
2508 | * (u_0). | |
2509 | * | |
2510 | * When a period "rolls over" and we have new u_0`, multiplying the previous | |
2511 | * sum again by y is sufficient to update: | |
2512 | * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... ) | |
2513 | * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}] | |
2514 | */ | |
0c1dc6b2 | 2515 | static __always_inline int __update_entity_runnable_avg(u64 now, int cpu, |
9d85f21c | 2516 | struct sched_avg *sa, |
36ee28e4 VG |
2517 | int runnable, |
2518 | int running) | |
9d85f21c | 2519 | { |
5b51f2f8 PT |
2520 | u64 delta, periods; |
2521 | u32 runnable_contrib; | |
9d85f21c | 2522 | int delta_w, decayed = 0; |
0c1dc6b2 | 2523 | unsigned long scale_freq = arch_scale_freq_capacity(NULL, cpu); |
9d85f21c PT |
2524 | |
2525 | delta = now - sa->last_runnable_update; | |
2526 | /* | |
2527 | * This should only happen when time goes backwards, which it | |
2528 | * unfortunately does during sched clock init when we swap over to TSC. | |
2529 | */ | |
2530 | if ((s64)delta < 0) { | |
2531 | sa->last_runnable_update = now; | |
2532 | return 0; | |
2533 | } | |
2534 | ||
2535 | /* | |
2536 | * Use 1024ns as the unit of measurement since it's a reasonable | |
2537 | * approximation of 1us and fast to compute. | |
2538 | */ | |
2539 | delta >>= 10; | |
2540 | if (!delta) | |
2541 | return 0; | |
2542 | sa->last_runnable_update = now; | |
2543 | ||
2544 | /* delta_w is the amount already accumulated against our next period */ | |
36ee28e4 | 2545 | delta_w = sa->avg_period % 1024; |
9d85f21c PT |
2546 | if (delta + delta_w >= 1024) { |
2547 | /* period roll-over */ | |
2548 | decayed = 1; | |
2549 | ||
2550 | /* | |
2551 | * Now that we know we're crossing a period boundary, figure | |
2552 | * out how much from delta we need to complete the current | |
2553 | * period and accrue it. | |
2554 | */ | |
2555 | delta_w = 1024 - delta_w; | |
5b51f2f8 PT |
2556 | if (runnable) |
2557 | sa->runnable_avg_sum += delta_w; | |
36ee28e4 | 2558 | if (running) |
0c1dc6b2 MR |
2559 | sa->running_avg_sum += delta_w * scale_freq |
2560 | >> SCHED_CAPACITY_SHIFT; | |
36ee28e4 | 2561 | sa->avg_period += delta_w; |
5b51f2f8 PT |
2562 | |
2563 | delta -= delta_w; | |
2564 | ||
2565 | /* Figure out how many additional periods this update spans */ | |
2566 | periods = delta / 1024; | |
2567 | delta %= 1024; | |
2568 | ||
2569 | sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum, | |
2570 | periods + 1); | |
36ee28e4 VG |
2571 | sa->running_avg_sum = decay_load(sa->running_avg_sum, |
2572 | periods + 1); | |
2573 | sa->avg_period = decay_load(sa->avg_period, | |
5b51f2f8 PT |
2574 | periods + 1); |
2575 | ||
2576 | /* Efficiently calculate \sum (1..n_period) 1024*y^i */ | |
2577 | runnable_contrib = __compute_runnable_contrib(periods); | |
2578 | if (runnable) | |
2579 | sa->runnable_avg_sum += runnable_contrib; | |
36ee28e4 | 2580 | if (running) |
0c1dc6b2 MR |
2581 | sa->running_avg_sum += runnable_contrib * scale_freq |
2582 | >> SCHED_CAPACITY_SHIFT; | |
36ee28e4 | 2583 | sa->avg_period += runnable_contrib; |
9d85f21c PT |
2584 | } |
2585 | ||
2586 | /* Remainder of delta accrued against u_0` */ | |
2587 | if (runnable) | |
2588 | sa->runnable_avg_sum += delta; | |
36ee28e4 | 2589 | if (running) |
0c1dc6b2 MR |
2590 | sa->running_avg_sum += delta * scale_freq |
2591 | >> SCHED_CAPACITY_SHIFT; | |
36ee28e4 | 2592 | sa->avg_period += delta; |
9d85f21c PT |
2593 | |
2594 | return decayed; | |
2595 | } | |
2596 | ||
9ee474f5 | 2597 | /* Synchronize an entity's decay with its parenting cfs_rq.*/ |
aff3e498 | 2598 | static inline u64 __synchronize_entity_decay(struct sched_entity *se) |
9ee474f5 PT |
2599 | { |
2600 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
2601 | u64 decays = atomic64_read(&cfs_rq->decay_counter); | |
2602 | ||
2603 | decays -= se->avg.decay_count; | |
63847600 | 2604 | se->avg.decay_count = 0; |
9ee474f5 | 2605 | if (!decays) |
aff3e498 | 2606 | return 0; |
9ee474f5 PT |
2607 | |
2608 | se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays); | |
36ee28e4 VG |
2609 | se->avg.utilization_avg_contrib = |
2610 | decay_load(se->avg.utilization_avg_contrib, decays); | |
aff3e498 PT |
2611 | |
2612 | return decays; | |
9ee474f5 PT |
2613 | } |
2614 | ||
c566e8e9 PT |
2615 | #ifdef CONFIG_FAIR_GROUP_SCHED |
2616 | static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq, | |
2617 | int force_update) | |
2618 | { | |
2619 | struct task_group *tg = cfs_rq->tg; | |
bf5b986e | 2620 | long tg_contrib; |
c566e8e9 PT |
2621 | |
2622 | tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg; | |
2623 | tg_contrib -= cfs_rq->tg_load_contrib; | |
2624 | ||
8236d907 JL |
2625 | if (!tg_contrib) |
2626 | return; | |
2627 | ||
bf5b986e AS |
2628 | if (force_update || abs(tg_contrib) > cfs_rq->tg_load_contrib / 8) { |
2629 | atomic_long_add(tg_contrib, &tg->load_avg); | |
c566e8e9 PT |
2630 | cfs_rq->tg_load_contrib += tg_contrib; |
2631 | } | |
2632 | } | |
8165e145 | 2633 | |
bb17f655 PT |
2634 | /* |
2635 | * Aggregate cfs_rq runnable averages into an equivalent task_group | |
2636 | * representation for computing load contributions. | |
2637 | */ | |
2638 | static inline void __update_tg_runnable_avg(struct sched_avg *sa, | |
2639 | struct cfs_rq *cfs_rq) | |
2640 | { | |
2641 | struct task_group *tg = cfs_rq->tg; | |
2642 | long contrib; | |
2643 | ||
2644 | /* The fraction of a cpu used by this cfs_rq */ | |
85b088e9 | 2645 | contrib = div_u64((u64)sa->runnable_avg_sum << NICE_0_SHIFT, |
36ee28e4 | 2646 | sa->avg_period + 1); |
bb17f655 PT |
2647 | contrib -= cfs_rq->tg_runnable_contrib; |
2648 | ||
2649 | if (abs(contrib) > cfs_rq->tg_runnable_contrib / 64) { | |
2650 | atomic_add(contrib, &tg->runnable_avg); | |
2651 | cfs_rq->tg_runnable_contrib += contrib; | |
2652 | } | |
2653 | } | |
2654 | ||
8165e145 PT |
2655 | static inline void __update_group_entity_contrib(struct sched_entity *se) |
2656 | { | |
2657 | struct cfs_rq *cfs_rq = group_cfs_rq(se); | |
2658 | struct task_group *tg = cfs_rq->tg; | |
bb17f655 PT |
2659 | int runnable_avg; |
2660 | ||
8165e145 PT |
2661 | u64 contrib; |
2662 | ||
2663 | contrib = cfs_rq->tg_load_contrib * tg->shares; | |
bf5b986e AS |
2664 | se->avg.load_avg_contrib = div_u64(contrib, |
2665 | atomic_long_read(&tg->load_avg) + 1); | |
bb17f655 PT |
2666 | |
2667 | /* | |
2668 | * For group entities we need to compute a correction term in the case | |
2669 | * that they are consuming <1 cpu so that we would contribute the same | |
2670 | * load as a task of equal weight. | |
2671 | * | |
2672 | * Explicitly co-ordinating this measurement would be expensive, but | |
2673 | * fortunately the sum of each cpus contribution forms a usable | |
2674 | * lower-bound on the true value. | |
2675 | * | |
2676 | * Consider the aggregate of 2 contributions. Either they are disjoint | |
2677 | * (and the sum represents true value) or they are disjoint and we are | |
2678 | * understating by the aggregate of their overlap. | |
2679 | * | |
2680 | * Extending this to N cpus, for a given overlap, the maximum amount we | |
2681 | * understand is then n_i(n_i+1)/2 * w_i where n_i is the number of | |
2682 | * cpus that overlap for this interval and w_i is the interval width. | |
2683 | * | |
2684 | * On a small machine; the first term is well-bounded which bounds the | |
2685 | * total error since w_i is a subset of the period. Whereas on a | |
2686 | * larger machine, while this first term can be larger, if w_i is the | |
2687 | * of consequential size guaranteed to see n_i*w_i quickly converge to | |
2688 | * our upper bound of 1-cpu. | |
2689 | */ | |
2690 | runnable_avg = atomic_read(&tg->runnable_avg); | |
2691 | if (runnable_avg < NICE_0_LOAD) { | |
2692 | se->avg.load_avg_contrib *= runnable_avg; | |
2693 | se->avg.load_avg_contrib >>= NICE_0_SHIFT; | |
2694 | } | |
8165e145 | 2695 | } |
f5f9739d DE |
2696 | |
2697 | static inline void update_rq_runnable_avg(struct rq *rq, int runnable) | |
2698 | { | |
0c1dc6b2 MR |
2699 | __update_entity_runnable_avg(rq_clock_task(rq), cpu_of(rq), &rq->avg, |
2700 | runnable, runnable); | |
f5f9739d DE |
2701 | __update_tg_runnable_avg(&rq->avg, &rq->cfs); |
2702 | } | |
6e83125c | 2703 | #else /* CONFIG_FAIR_GROUP_SCHED */ |
c566e8e9 PT |
2704 | static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq, |
2705 | int force_update) {} | |
bb17f655 PT |
2706 | static inline void __update_tg_runnable_avg(struct sched_avg *sa, |
2707 | struct cfs_rq *cfs_rq) {} | |
8165e145 | 2708 | static inline void __update_group_entity_contrib(struct sched_entity *se) {} |
f5f9739d | 2709 | static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {} |
6e83125c | 2710 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
c566e8e9 | 2711 | |
8165e145 PT |
2712 | static inline void __update_task_entity_contrib(struct sched_entity *se) |
2713 | { | |
2714 | u32 contrib; | |
2715 | ||
2716 | /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */ | |
2717 | contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight); | |
36ee28e4 | 2718 | contrib /= (se->avg.avg_period + 1); |
8165e145 PT |
2719 | se->avg.load_avg_contrib = scale_load(contrib); |
2720 | } | |
2721 | ||
2dac754e PT |
2722 | /* Compute the current contribution to load_avg by se, return any delta */ |
2723 | static long __update_entity_load_avg_contrib(struct sched_entity *se) | |
2724 | { | |
2725 | long old_contrib = se->avg.load_avg_contrib; | |
2726 | ||
8165e145 PT |
2727 | if (entity_is_task(se)) { |
2728 | __update_task_entity_contrib(se); | |
2729 | } else { | |
bb17f655 | 2730 | __update_tg_runnable_avg(&se->avg, group_cfs_rq(se)); |
8165e145 PT |
2731 | __update_group_entity_contrib(se); |
2732 | } | |
2dac754e PT |
2733 | |
2734 | return se->avg.load_avg_contrib - old_contrib; | |
2735 | } | |
2736 | ||
36ee28e4 VG |
2737 | |
2738 | static inline void __update_task_entity_utilization(struct sched_entity *se) | |
2739 | { | |
2740 | u32 contrib; | |
2741 | ||
2742 | /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */ | |
2743 | contrib = se->avg.running_avg_sum * scale_load_down(SCHED_LOAD_SCALE); | |
2744 | contrib /= (se->avg.avg_period + 1); | |
2745 | se->avg.utilization_avg_contrib = scale_load(contrib); | |
2746 | } | |
2747 | ||
2748 | static long __update_entity_utilization_avg_contrib(struct sched_entity *se) | |
2749 | { | |
2750 | long old_contrib = se->avg.utilization_avg_contrib; | |
2751 | ||
2752 | if (entity_is_task(se)) | |
2753 | __update_task_entity_utilization(se); | |
21f44866 MR |
2754 | else |
2755 | se->avg.utilization_avg_contrib = | |
2756 | group_cfs_rq(se)->utilization_load_avg; | |
36ee28e4 VG |
2757 | |
2758 | return se->avg.utilization_avg_contrib - old_contrib; | |
2759 | } | |
2760 | ||
9ee474f5 PT |
2761 | static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq, |
2762 | long load_contrib) | |
2763 | { | |
2764 | if (likely(load_contrib < cfs_rq->blocked_load_avg)) | |
2765 | cfs_rq->blocked_load_avg -= load_contrib; | |
2766 | else | |
2767 | cfs_rq->blocked_load_avg = 0; | |
2768 | } | |
2769 | ||
f1b17280 PT |
2770 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq); |
2771 | ||
9d85f21c | 2772 | /* Update a sched_entity's runnable average */ |
9ee474f5 PT |
2773 | static inline void update_entity_load_avg(struct sched_entity *se, |
2774 | int update_cfs_rq) | |
9d85f21c | 2775 | { |
2dac754e | 2776 | struct cfs_rq *cfs_rq = cfs_rq_of(se); |
36ee28e4 | 2777 | long contrib_delta, utilization_delta; |
0c1dc6b2 | 2778 | int cpu = cpu_of(rq_of(cfs_rq)); |
f1b17280 | 2779 | u64 now; |
2dac754e | 2780 | |
f1b17280 PT |
2781 | /* |
2782 | * For a group entity we need to use their owned cfs_rq_clock_task() in | |
2783 | * case they are the parent of a throttled hierarchy. | |
2784 | */ | |
2785 | if (entity_is_task(se)) | |
2786 | now = cfs_rq_clock_task(cfs_rq); | |
2787 | else | |
2788 | now = cfs_rq_clock_task(group_cfs_rq(se)); | |
2789 | ||
0c1dc6b2 | 2790 | if (!__update_entity_runnable_avg(now, cpu, &se->avg, se->on_rq, |
36ee28e4 | 2791 | cfs_rq->curr == se)) |
2dac754e PT |
2792 | return; |
2793 | ||
2794 | contrib_delta = __update_entity_load_avg_contrib(se); | |
36ee28e4 | 2795 | utilization_delta = __update_entity_utilization_avg_contrib(se); |
9ee474f5 PT |
2796 | |
2797 | if (!update_cfs_rq) | |
2798 | return; | |
2799 | ||
36ee28e4 | 2800 | if (se->on_rq) { |
2dac754e | 2801 | cfs_rq->runnable_load_avg += contrib_delta; |
36ee28e4 VG |
2802 | cfs_rq->utilization_load_avg += utilization_delta; |
2803 | } else { | |
9ee474f5 | 2804 | subtract_blocked_load_contrib(cfs_rq, -contrib_delta); |
36ee28e4 | 2805 | } |
9ee474f5 PT |
2806 | } |
2807 | ||
2808 | /* | |
2809 | * Decay the load contributed by all blocked children and account this so that | |
2810 | * their contribution may appropriately discounted when they wake up. | |
2811 | */ | |
aff3e498 | 2812 | static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update) |
9ee474f5 | 2813 | { |
f1b17280 | 2814 | u64 now = cfs_rq_clock_task(cfs_rq) >> 20; |
9ee474f5 PT |
2815 | u64 decays; |
2816 | ||
2817 | decays = now - cfs_rq->last_decay; | |
aff3e498 | 2818 | if (!decays && !force_update) |
9ee474f5 PT |
2819 | return; |
2820 | ||
2509940f AS |
2821 | if (atomic_long_read(&cfs_rq->removed_load)) { |
2822 | unsigned long removed_load; | |
2823 | removed_load = atomic_long_xchg(&cfs_rq->removed_load, 0); | |
aff3e498 PT |
2824 | subtract_blocked_load_contrib(cfs_rq, removed_load); |
2825 | } | |
9ee474f5 | 2826 | |
aff3e498 PT |
2827 | if (decays) { |
2828 | cfs_rq->blocked_load_avg = decay_load(cfs_rq->blocked_load_avg, | |
2829 | decays); | |
2830 | atomic64_add(decays, &cfs_rq->decay_counter); | |
2831 | cfs_rq->last_decay = now; | |
2832 | } | |
c566e8e9 PT |
2833 | |
2834 | __update_cfs_rq_tg_load_contrib(cfs_rq, force_update); | |
9d85f21c | 2835 | } |
18bf2805 | 2836 | |
2dac754e PT |
2837 | /* Add the load generated by se into cfs_rq's child load-average */ |
2838 | static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, | |
9ee474f5 PT |
2839 | struct sched_entity *se, |
2840 | int wakeup) | |
2dac754e | 2841 | { |
aff3e498 PT |
2842 | /* |
2843 | * We track migrations using entity decay_count <= 0, on a wake-up | |
2844 | * migration we use a negative decay count to track the remote decays | |
2845 | * accumulated while sleeping. | |
a75cdaa9 AS |
2846 | * |
2847 | * Newly forked tasks are enqueued with se->avg.decay_count == 0, they | |
2848 | * are seen by enqueue_entity_load_avg() as a migration with an already | |
2849 | * constructed load_avg_contrib. | |
aff3e498 PT |
2850 | */ |
2851 | if (unlikely(se->avg.decay_count <= 0)) { | |
78becc27 | 2852 | se->avg.last_runnable_update = rq_clock_task(rq_of(cfs_rq)); |
aff3e498 PT |
2853 | if (se->avg.decay_count) { |
2854 | /* | |
2855 | * In a wake-up migration we have to approximate the | |
2856 | * time sleeping. This is because we can't synchronize | |
2857 | * clock_task between the two cpus, and it is not | |
2858 | * guaranteed to be read-safe. Instead, we can | |
2859 | * approximate this using our carried decays, which are | |
2860 | * explicitly atomically readable. | |
2861 | */ | |
2862 | se->avg.last_runnable_update -= (-se->avg.decay_count) | |
2863 | << 20; | |
2864 | update_entity_load_avg(se, 0); | |
2865 | /* Indicate that we're now synchronized and on-rq */ | |
2866 | se->avg.decay_count = 0; | |
2867 | } | |
9ee474f5 PT |
2868 | wakeup = 0; |
2869 | } else { | |
9390675a | 2870 | __synchronize_entity_decay(se); |
9ee474f5 PT |
2871 | } |
2872 | ||
aff3e498 PT |
2873 | /* migrated tasks did not contribute to our blocked load */ |
2874 | if (wakeup) { | |
9ee474f5 | 2875 | subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib); |
aff3e498 PT |
2876 | update_entity_load_avg(se, 0); |
2877 | } | |
9ee474f5 | 2878 | |
2dac754e | 2879 | cfs_rq->runnable_load_avg += se->avg.load_avg_contrib; |
36ee28e4 | 2880 | cfs_rq->utilization_load_avg += se->avg.utilization_avg_contrib; |
aff3e498 PT |
2881 | /* we force update consideration on load-balancer moves */ |
2882 | update_cfs_rq_blocked_load(cfs_rq, !wakeup); | |
2dac754e PT |
2883 | } |
2884 | ||
9ee474f5 PT |
2885 | /* |
2886 | * Remove se's load from this cfs_rq child load-average, if the entity is | |
2887 | * transitioning to a blocked state we track its projected decay using | |
2888 | * blocked_load_avg. | |
2889 | */ | |
2dac754e | 2890 | static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq, |
9ee474f5 PT |
2891 | struct sched_entity *se, |
2892 | int sleep) | |
2dac754e | 2893 | { |
9ee474f5 | 2894 | update_entity_load_avg(se, 1); |
aff3e498 PT |
2895 | /* we force update consideration on load-balancer moves */ |
2896 | update_cfs_rq_blocked_load(cfs_rq, !sleep); | |
9ee474f5 | 2897 | |
2dac754e | 2898 | cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib; |
36ee28e4 | 2899 | cfs_rq->utilization_load_avg -= se->avg.utilization_avg_contrib; |
9ee474f5 PT |
2900 | if (sleep) { |
2901 | cfs_rq->blocked_load_avg += se->avg.load_avg_contrib; | |
2902 | se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter); | |
2903 | } /* migrations, e.g. sleep=0 leave decay_count == 0 */ | |
2dac754e | 2904 | } |
642dbc39 VG |
2905 | |
2906 | /* | |
2907 | * Update the rq's load with the elapsed running time before entering | |
2908 | * idle. if the last scheduled task is not a CFS task, idle_enter will | |
2909 | * be the only way to update the runnable statistic. | |
2910 | */ | |
2911 | void idle_enter_fair(struct rq *this_rq) | |
2912 | { | |
2913 | update_rq_runnable_avg(this_rq, 1); | |
2914 | } | |
2915 | ||
2916 | /* | |
2917 | * Update the rq's load with the elapsed idle time before a task is | |
2918 | * scheduled. if the newly scheduled task is not a CFS task, idle_exit will | |
2919 | * be the only way to update the runnable statistic. | |
2920 | */ | |
2921 | void idle_exit_fair(struct rq *this_rq) | |
2922 | { | |
2923 | update_rq_runnable_avg(this_rq, 0); | |
2924 | } | |
2925 | ||
6e83125c PZ |
2926 | static int idle_balance(struct rq *this_rq); |
2927 | ||
38033c37 PZ |
2928 | #else /* CONFIG_SMP */ |
2929 | ||
9ee474f5 PT |
2930 | static inline void update_entity_load_avg(struct sched_entity *se, |
2931 | int update_cfs_rq) {} | |
18bf2805 | 2932 | static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {} |
2dac754e | 2933 | static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, |
9ee474f5 PT |
2934 | struct sched_entity *se, |
2935 | int wakeup) {} | |
2dac754e | 2936 | static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq, |
9ee474f5 PT |
2937 | struct sched_entity *se, |
2938 | int sleep) {} | |
aff3e498 PT |
2939 | static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, |
2940 | int force_update) {} | |
6e83125c PZ |
2941 | |
2942 | static inline int idle_balance(struct rq *rq) | |
2943 | { | |
2944 | return 0; | |
2945 | } | |
2946 | ||
38033c37 | 2947 | #endif /* CONFIG_SMP */ |
9d85f21c | 2948 | |
2396af69 | 2949 | static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 2950 | { |
bf0f6f24 | 2951 | #ifdef CONFIG_SCHEDSTATS |
e414314c PZ |
2952 | struct task_struct *tsk = NULL; |
2953 | ||
2954 | if (entity_is_task(se)) | |
2955 | tsk = task_of(se); | |
2956 | ||
41acab88 | 2957 | if (se->statistics.sleep_start) { |
78becc27 | 2958 | u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.sleep_start; |
bf0f6f24 IM |
2959 | |
2960 | if ((s64)delta < 0) | |
2961 | delta = 0; | |
2962 | ||
41acab88 LDM |
2963 | if (unlikely(delta > se->statistics.sleep_max)) |
2964 | se->statistics.sleep_max = delta; | |
bf0f6f24 | 2965 | |
8c79a045 | 2966 | se->statistics.sleep_start = 0; |
41acab88 | 2967 | se->statistics.sum_sleep_runtime += delta; |
9745512c | 2968 | |
768d0c27 | 2969 | if (tsk) { |
e414314c | 2970 | account_scheduler_latency(tsk, delta >> 10, 1); |
768d0c27 PZ |
2971 | trace_sched_stat_sleep(tsk, delta); |
2972 | } | |
bf0f6f24 | 2973 | } |
41acab88 | 2974 | if (se->statistics.block_start) { |
78becc27 | 2975 | u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.block_start; |
bf0f6f24 IM |
2976 | |
2977 | if ((s64)delta < 0) | |
2978 | delta = 0; | |
2979 | ||
41acab88 LDM |
2980 | if (unlikely(delta > se->statistics.block_max)) |
2981 | se->statistics.block_max = delta; | |
bf0f6f24 | 2982 | |
8c79a045 | 2983 | se->statistics.block_start = 0; |
41acab88 | 2984 | se->statistics.sum_sleep_runtime += delta; |
30084fbd | 2985 | |
e414314c | 2986 | if (tsk) { |
8f0dfc34 | 2987 | if (tsk->in_iowait) { |
41acab88 LDM |
2988 | se->statistics.iowait_sum += delta; |
2989 | se->statistics.iowait_count++; | |
768d0c27 | 2990 | trace_sched_stat_iowait(tsk, delta); |
8f0dfc34 AV |
2991 | } |
2992 | ||
b781a602 AV |
2993 | trace_sched_stat_blocked(tsk, delta); |
2994 | ||
e414314c PZ |
2995 | /* |
2996 | * Blocking time is in units of nanosecs, so shift by | |
2997 | * 20 to get a milliseconds-range estimation of the | |
2998 | * amount of time that the task spent sleeping: | |
2999 | */ | |
3000 | if (unlikely(prof_on == SLEEP_PROFILING)) { | |
3001 | profile_hits(SLEEP_PROFILING, | |
3002 | (void *)get_wchan(tsk), | |
3003 | delta >> 20); | |
3004 | } | |
3005 | account_scheduler_latency(tsk, delta >> 10, 0); | |
30084fbd | 3006 | } |
bf0f6f24 IM |
3007 | } |
3008 | #endif | |
3009 | } | |
3010 | ||
ddc97297 PZ |
3011 | static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se) |
3012 | { | |
3013 | #ifdef CONFIG_SCHED_DEBUG | |
3014 | s64 d = se->vruntime - cfs_rq->min_vruntime; | |
3015 | ||
3016 | if (d < 0) | |
3017 | d = -d; | |
3018 | ||
3019 | if (d > 3*sysctl_sched_latency) | |
3020 | schedstat_inc(cfs_rq, nr_spread_over); | |
3021 | #endif | |
3022 | } | |
3023 | ||
aeb73b04 PZ |
3024 | static void |
3025 | place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) | |
3026 | { | |
1af5f730 | 3027 | u64 vruntime = cfs_rq->min_vruntime; |
94dfb5e7 | 3028 | |
2cb8600e PZ |
3029 | /* |
3030 | * The 'current' period is already promised to the current tasks, | |
3031 | * however the extra weight of the new task will slow them down a | |
3032 | * little, place the new task so that it fits in the slot that | |
3033 | * stays open at the end. | |
3034 | */ | |
94dfb5e7 | 3035 | if (initial && sched_feat(START_DEBIT)) |
f9c0b095 | 3036 | vruntime += sched_vslice(cfs_rq, se); |
aeb73b04 | 3037 | |
a2e7a7eb | 3038 | /* sleeps up to a single latency don't count. */ |
5ca9880c | 3039 | if (!initial) { |
a2e7a7eb | 3040 | unsigned long thresh = sysctl_sched_latency; |
a7be37ac | 3041 | |
a2e7a7eb MG |
3042 | /* |
3043 | * Halve their sleep time's effect, to allow | |
3044 | * for a gentler effect of sleepers: | |
3045 | */ | |
3046 | if (sched_feat(GENTLE_FAIR_SLEEPERS)) | |
3047 | thresh >>= 1; | |
51e0304c | 3048 | |
a2e7a7eb | 3049 | vruntime -= thresh; |
aeb73b04 PZ |
3050 | } |
3051 | ||
b5d9d734 | 3052 | /* ensure we never gain time by being placed backwards. */ |
16c8f1c7 | 3053 | se->vruntime = max_vruntime(se->vruntime, vruntime); |
aeb73b04 PZ |
3054 | } |
3055 | ||
d3d9dc33 PT |
3056 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq); |
3057 | ||
bf0f6f24 | 3058 | static void |
88ec22d3 | 3059 | enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 3060 | { |
88ec22d3 PZ |
3061 | /* |
3062 | * Update the normalized vruntime before updating min_vruntime | |
0fc576d5 | 3063 | * through calling update_curr(). |
88ec22d3 | 3064 | */ |
371fd7e7 | 3065 | if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING)) |
88ec22d3 PZ |
3066 | se->vruntime += cfs_rq->min_vruntime; |
3067 | ||
bf0f6f24 | 3068 | /* |
a2a2d680 | 3069 | * Update run-time statistics of the 'current'. |
bf0f6f24 | 3070 | */ |
b7cc0896 | 3071 | update_curr(cfs_rq); |
f269ae04 | 3072 | enqueue_entity_load_avg(cfs_rq, se, flags & ENQUEUE_WAKEUP); |
17bc14b7 LT |
3073 | account_entity_enqueue(cfs_rq, se); |
3074 | update_cfs_shares(cfs_rq); | |
bf0f6f24 | 3075 | |
88ec22d3 | 3076 | if (flags & ENQUEUE_WAKEUP) { |
aeb73b04 | 3077 | place_entity(cfs_rq, se, 0); |
2396af69 | 3078 | enqueue_sleeper(cfs_rq, se); |
e9acbff6 | 3079 | } |
bf0f6f24 | 3080 | |
d2417e5a | 3081 | update_stats_enqueue(cfs_rq, se); |
ddc97297 | 3082 | check_spread(cfs_rq, se); |
83b699ed SV |
3083 | if (se != cfs_rq->curr) |
3084 | __enqueue_entity(cfs_rq, se); | |
2069dd75 | 3085 | se->on_rq = 1; |
3d4b47b4 | 3086 | |
d3d9dc33 | 3087 | if (cfs_rq->nr_running == 1) { |
3d4b47b4 | 3088 | list_add_leaf_cfs_rq(cfs_rq); |
d3d9dc33 PT |
3089 | check_enqueue_throttle(cfs_rq); |
3090 | } | |
bf0f6f24 IM |
3091 | } |
3092 | ||
2c13c919 | 3093 | static void __clear_buddies_last(struct sched_entity *se) |
2002c695 | 3094 | { |
2c13c919 RR |
3095 | for_each_sched_entity(se) { |
3096 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 3097 | if (cfs_rq->last != se) |
2c13c919 | 3098 | break; |
f1044799 PZ |
3099 | |
3100 | cfs_rq->last = NULL; | |
2c13c919 RR |
3101 | } |
3102 | } | |
2002c695 | 3103 | |
2c13c919 RR |
3104 | static void __clear_buddies_next(struct sched_entity *se) |
3105 | { | |
3106 | for_each_sched_entity(se) { | |
3107 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 3108 | if (cfs_rq->next != se) |
2c13c919 | 3109 | break; |
f1044799 PZ |
3110 | |
3111 | cfs_rq->next = NULL; | |
2c13c919 | 3112 | } |
2002c695 PZ |
3113 | } |
3114 | ||
ac53db59 RR |
3115 | static void __clear_buddies_skip(struct sched_entity *se) |
3116 | { | |
3117 | for_each_sched_entity(se) { | |
3118 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 3119 | if (cfs_rq->skip != se) |
ac53db59 | 3120 | break; |
f1044799 PZ |
3121 | |
3122 | cfs_rq->skip = NULL; | |
ac53db59 RR |
3123 | } |
3124 | } | |
3125 | ||
a571bbea PZ |
3126 | static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) |
3127 | { | |
2c13c919 RR |
3128 | if (cfs_rq->last == se) |
3129 | __clear_buddies_last(se); | |
3130 | ||
3131 | if (cfs_rq->next == se) | |
3132 | __clear_buddies_next(se); | |
ac53db59 RR |
3133 | |
3134 | if (cfs_rq->skip == se) | |
3135 | __clear_buddies_skip(se); | |
a571bbea PZ |
3136 | } |
3137 | ||
6c16a6dc | 3138 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
d8b4986d | 3139 | |
bf0f6f24 | 3140 | static void |
371fd7e7 | 3141 | dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 3142 | { |
a2a2d680 DA |
3143 | /* |
3144 | * Update run-time statistics of the 'current'. | |
3145 | */ | |
3146 | update_curr(cfs_rq); | |
17bc14b7 | 3147 | dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP); |
a2a2d680 | 3148 | |
19b6a2e3 | 3149 | update_stats_dequeue(cfs_rq, se); |
371fd7e7 | 3150 | if (flags & DEQUEUE_SLEEP) { |
67e9fb2a | 3151 | #ifdef CONFIG_SCHEDSTATS |
bf0f6f24 IM |
3152 | if (entity_is_task(se)) { |
3153 | struct task_struct *tsk = task_of(se); | |
3154 | ||
3155 | if (tsk->state & TASK_INTERRUPTIBLE) | |
78becc27 | 3156 | se->statistics.sleep_start = rq_clock(rq_of(cfs_rq)); |
bf0f6f24 | 3157 | if (tsk->state & TASK_UNINTERRUPTIBLE) |
78becc27 | 3158 | se->statistics.block_start = rq_clock(rq_of(cfs_rq)); |
bf0f6f24 | 3159 | } |
db36cc7d | 3160 | #endif |
67e9fb2a PZ |
3161 | } |
3162 | ||
2002c695 | 3163 | clear_buddies(cfs_rq, se); |
4793241b | 3164 | |
83b699ed | 3165 | if (se != cfs_rq->curr) |
30cfdcfc | 3166 | __dequeue_entity(cfs_rq, se); |
17bc14b7 | 3167 | se->on_rq = 0; |
30cfdcfc | 3168 | account_entity_dequeue(cfs_rq, se); |
88ec22d3 PZ |
3169 | |
3170 | /* | |
3171 | * Normalize the entity after updating the min_vruntime because the | |
3172 | * update can refer to the ->curr item and we need to reflect this | |
3173 | * movement in our normalized position. | |
3174 | */ | |
371fd7e7 | 3175 | if (!(flags & DEQUEUE_SLEEP)) |
88ec22d3 | 3176 | se->vruntime -= cfs_rq->min_vruntime; |
1e876231 | 3177 | |
d8b4986d PT |
3178 | /* return excess runtime on last dequeue */ |
3179 | return_cfs_rq_runtime(cfs_rq); | |
3180 | ||
1e876231 | 3181 | update_min_vruntime(cfs_rq); |
17bc14b7 | 3182 | update_cfs_shares(cfs_rq); |
bf0f6f24 IM |
3183 | } |
3184 | ||
3185 | /* | |
3186 | * Preempt the current task with a newly woken task if needed: | |
3187 | */ | |
7c92e54f | 3188 | static void |
2e09bf55 | 3189 | check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
bf0f6f24 | 3190 | { |
11697830 | 3191 | unsigned long ideal_runtime, delta_exec; |
f4cfb33e WX |
3192 | struct sched_entity *se; |
3193 | s64 delta; | |
11697830 | 3194 | |
6d0f0ebd | 3195 | ideal_runtime = sched_slice(cfs_rq, curr); |
11697830 | 3196 | delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; |
a9f3e2b5 | 3197 | if (delta_exec > ideal_runtime) { |
8875125e | 3198 | resched_curr(rq_of(cfs_rq)); |
a9f3e2b5 MG |
3199 | /* |
3200 | * The current task ran long enough, ensure it doesn't get | |
3201 | * re-elected due to buddy favours. | |
3202 | */ | |
3203 | clear_buddies(cfs_rq, curr); | |
f685ceac MG |
3204 | return; |
3205 | } | |
3206 | ||
3207 | /* | |
3208 | * Ensure that a task that missed wakeup preemption by a | |
3209 | * narrow margin doesn't have to wait for a full slice. | |
3210 | * This also mitigates buddy induced latencies under load. | |
3211 | */ | |
f685ceac MG |
3212 | if (delta_exec < sysctl_sched_min_granularity) |
3213 | return; | |
3214 | ||
f4cfb33e WX |
3215 | se = __pick_first_entity(cfs_rq); |
3216 | delta = curr->vruntime - se->vruntime; | |
f685ceac | 3217 | |
f4cfb33e WX |
3218 | if (delta < 0) |
3219 | return; | |
d7d82944 | 3220 | |
f4cfb33e | 3221 | if (delta > ideal_runtime) |
8875125e | 3222 | resched_curr(rq_of(cfs_rq)); |
bf0f6f24 IM |
3223 | } |
3224 | ||
83b699ed | 3225 | static void |
8494f412 | 3226 | set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 3227 | { |
83b699ed SV |
3228 | /* 'current' is not kept within the tree. */ |
3229 | if (se->on_rq) { | |
3230 | /* | |
3231 | * Any task has to be enqueued before it get to execute on | |
3232 | * a CPU. So account for the time it spent waiting on the | |
3233 | * runqueue. | |
3234 | */ | |
3235 | update_stats_wait_end(cfs_rq, se); | |
3236 | __dequeue_entity(cfs_rq, se); | |
36ee28e4 | 3237 | update_entity_load_avg(se, 1); |
83b699ed SV |
3238 | } |
3239 | ||
79303e9e | 3240 | update_stats_curr_start(cfs_rq, se); |
429d43bc | 3241 | cfs_rq->curr = se; |
eba1ed4b IM |
3242 | #ifdef CONFIG_SCHEDSTATS |
3243 | /* | |
3244 | * Track our maximum slice length, if the CPU's load is at | |
3245 | * least twice that of our own weight (i.e. dont track it | |
3246 | * when there are only lesser-weight tasks around): | |
3247 | */ | |
495eca49 | 3248 | if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) { |
41acab88 | 3249 | se->statistics.slice_max = max(se->statistics.slice_max, |
eba1ed4b IM |
3250 | se->sum_exec_runtime - se->prev_sum_exec_runtime); |
3251 | } | |
3252 | #endif | |
4a55b450 | 3253 | se->prev_sum_exec_runtime = se->sum_exec_runtime; |
bf0f6f24 IM |
3254 | } |
3255 | ||
3f3a4904 PZ |
3256 | static int |
3257 | wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se); | |
3258 | ||
ac53db59 RR |
3259 | /* |
3260 | * Pick the next process, keeping these things in mind, in this order: | |
3261 | * 1) keep things fair between processes/task groups | |
3262 | * 2) pick the "next" process, since someone really wants that to run | |
3263 | * 3) pick the "last" process, for cache locality | |
3264 | * 4) do not run the "skip" process, if something else is available | |
3265 | */ | |
678d5718 PZ |
3266 | static struct sched_entity * |
3267 | pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) | |
aa2ac252 | 3268 | { |
678d5718 PZ |
3269 | struct sched_entity *left = __pick_first_entity(cfs_rq); |
3270 | struct sched_entity *se; | |
3271 | ||
3272 | /* | |
3273 | * If curr is set we have to see if its left of the leftmost entity | |
3274 | * still in the tree, provided there was anything in the tree at all. | |
3275 | */ | |
3276 | if (!left || (curr && entity_before(curr, left))) | |
3277 | left = curr; | |
3278 | ||
3279 | se = left; /* ideally we run the leftmost entity */ | |
f4b6755f | 3280 | |
ac53db59 RR |
3281 | /* |
3282 | * Avoid running the skip buddy, if running something else can | |
3283 | * be done without getting too unfair. | |
3284 | */ | |
3285 | if (cfs_rq->skip == se) { | |
678d5718 PZ |
3286 | struct sched_entity *second; |
3287 | ||
3288 | if (se == curr) { | |
3289 | second = __pick_first_entity(cfs_rq); | |
3290 | } else { | |
3291 | second = __pick_next_entity(se); | |
3292 | if (!second || (curr && entity_before(curr, second))) | |
3293 | second = curr; | |
3294 | } | |
3295 | ||
ac53db59 RR |
3296 | if (second && wakeup_preempt_entity(second, left) < 1) |
3297 | se = second; | |
3298 | } | |
aa2ac252 | 3299 | |
f685ceac MG |
3300 | /* |
3301 | * Prefer last buddy, try to return the CPU to a preempted task. | |
3302 | */ | |
3303 | if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) | |
3304 | se = cfs_rq->last; | |
3305 | ||
ac53db59 RR |
3306 | /* |
3307 | * Someone really wants this to run. If it's not unfair, run it. | |
3308 | */ | |
3309 | if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) | |
3310 | se = cfs_rq->next; | |
3311 | ||
f685ceac | 3312 | clear_buddies(cfs_rq, se); |
4793241b PZ |
3313 | |
3314 | return se; | |
aa2ac252 PZ |
3315 | } |
3316 | ||
678d5718 | 3317 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
d3d9dc33 | 3318 | |
ab6cde26 | 3319 | static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) |
bf0f6f24 IM |
3320 | { |
3321 | /* | |
3322 | * If still on the runqueue then deactivate_task() | |
3323 | * was not called and update_curr() has to be done: | |
3324 | */ | |
3325 | if (prev->on_rq) | |
b7cc0896 | 3326 | update_curr(cfs_rq); |
bf0f6f24 | 3327 | |
d3d9dc33 PT |
3328 | /* throttle cfs_rqs exceeding runtime */ |
3329 | check_cfs_rq_runtime(cfs_rq); | |
3330 | ||
ddc97297 | 3331 | check_spread(cfs_rq, prev); |
30cfdcfc | 3332 | if (prev->on_rq) { |
5870db5b | 3333 | update_stats_wait_start(cfs_rq, prev); |
30cfdcfc DA |
3334 | /* Put 'current' back into the tree. */ |
3335 | __enqueue_entity(cfs_rq, prev); | |
9d85f21c | 3336 | /* in !on_rq case, update occurred at dequeue */ |
9ee474f5 | 3337 | update_entity_load_avg(prev, 1); |
30cfdcfc | 3338 | } |
429d43bc | 3339 | cfs_rq->curr = NULL; |
bf0f6f24 IM |
3340 | } |
3341 | ||
8f4d37ec PZ |
3342 | static void |
3343 | entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) | |
bf0f6f24 | 3344 | { |
bf0f6f24 | 3345 | /* |
30cfdcfc | 3346 | * Update run-time statistics of the 'current'. |
bf0f6f24 | 3347 | */ |
30cfdcfc | 3348 | update_curr(cfs_rq); |
bf0f6f24 | 3349 | |
9d85f21c PT |
3350 | /* |
3351 | * Ensure that runnable average is periodically updated. | |
3352 | */ | |
9ee474f5 | 3353 | update_entity_load_avg(curr, 1); |
aff3e498 | 3354 | update_cfs_rq_blocked_load(cfs_rq, 1); |
bf0bd948 | 3355 | update_cfs_shares(cfs_rq); |
9d85f21c | 3356 | |
8f4d37ec PZ |
3357 | #ifdef CONFIG_SCHED_HRTICK |
3358 | /* | |
3359 | * queued ticks are scheduled to match the slice, so don't bother | |
3360 | * validating it and just reschedule. | |
3361 | */ | |
983ed7a6 | 3362 | if (queued) { |
8875125e | 3363 | resched_curr(rq_of(cfs_rq)); |
983ed7a6 HH |
3364 | return; |
3365 | } | |
8f4d37ec PZ |
3366 | /* |
3367 | * don't let the period tick interfere with the hrtick preemption | |
3368 | */ | |
3369 | if (!sched_feat(DOUBLE_TICK) && | |
3370 | hrtimer_active(&rq_of(cfs_rq)->hrtick_timer)) | |
3371 | return; | |
3372 | #endif | |
3373 | ||
2c2efaed | 3374 | if (cfs_rq->nr_running > 1) |
2e09bf55 | 3375 | check_preempt_tick(cfs_rq, curr); |
bf0f6f24 IM |
3376 | } |
3377 | ||
ab84d31e PT |
3378 | |
3379 | /************************************************** | |
3380 | * CFS bandwidth control machinery | |
3381 | */ | |
3382 | ||
3383 | #ifdef CONFIG_CFS_BANDWIDTH | |
029632fb PZ |
3384 | |
3385 | #ifdef HAVE_JUMP_LABEL | |
c5905afb | 3386 | static struct static_key __cfs_bandwidth_used; |
029632fb PZ |
3387 | |
3388 | static inline bool cfs_bandwidth_used(void) | |
3389 | { | |
c5905afb | 3390 | return static_key_false(&__cfs_bandwidth_used); |
029632fb PZ |
3391 | } |
3392 | ||
1ee14e6c | 3393 | void cfs_bandwidth_usage_inc(void) |
029632fb | 3394 | { |
1ee14e6c BS |
3395 | static_key_slow_inc(&__cfs_bandwidth_used); |
3396 | } | |
3397 | ||
3398 | void cfs_bandwidth_usage_dec(void) | |
3399 | { | |
3400 | static_key_slow_dec(&__cfs_bandwidth_used); | |
029632fb PZ |
3401 | } |
3402 | #else /* HAVE_JUMP_LABEL */ | |
3403 | static bool cfs_bandwidth_used(void) | |
3404 | { | |
3405 | return true; | |
3406 | } | |
3407 | ||
1ee14e6c BS |
3408 | void cfs_bandwidth_usage_inc(void) {} |
3409 | void cfs_bandwidth_usage_dec(void) {} | |
029632fb PZ |
3410 | #endif /* HAVE_JUMP_LABEL */ |
3411 | ||
ab84d31e PT |
3412 | /* |
3413 | * default period for cfs group bandwidth. | |
3414 | * default: 0.1s, units: nanoseconds | |
3415 | */ | |
3416 | static inline u64 default_cfs_period(void) | |
3417 | { | |
3418 | return 100000000ULL; | |
3419 | } | |
ec12cb7f PT |
3420 | |
3421 | static inline u64 sched_cfs_bandwidth_slice(void) | |
3422 | { | |
3423 | return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC; | |
3424 | } | |
3425 | ||
a9cf55b2 PT |
3426 | /* |
3427 | * Replenish runtime according to assigned quota and update expiration time. | |
3428 | * We use sched_clock_cpu directly instead of rq->clock to avoid adding | |
3429 | * additional synchronization around rq->lock. | |
3430 | * | |
3431 | * requires cfs_b->lock | |
3432 | */ | |
029632fb | 3433 | void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b) |
a9cf55b2 PT |
3434 | { |
3435 | u64 now; | |
3436 | ||
3437 | if (cfs_b->quota == RUNTIME_INF) | |
3438 | return; | |
3439 | ||
3440 | now = sched_clock_cpu(smp_processor_id()); | |
3441 | cfs_b->runtime = cfs_b->quota; | |
3442 | cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period); | |
3443 | } | |
3444 | ||
029632fb PZ |
3445 | static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
3446 | { | |
3447 | return &tg->cfs_bandwidth; | |
3448 | } | |
3449 | ||
f1b17280 PT |
3450 | /* rq->task_clock normalized against any time this cfs_rq has spent throttled */ |
3451 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) | |
3452 | { | |
3453 | if (unlikely(cfs_rq->throttle_count)) | |
3454 | return cfs_rq->throttled_clock_task; | |
3455 | ||
78becc27 | 3456 | return rq_clock_task(rq_of(cfs_rq)) - cfs_rq->throttled_clock_task_time; |
f1b17280 PT |
3457 | } |
3458 | ||
85dac906 PT |
3459 | /* returns 0 on failure to allocate runtime */ |
3460 | static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
ec12cb7f PT |
3461 | { |
3462 | struct task_group *tg = cfs_rq->tg; | |
3463 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg); | |
a9cf55b2 | 3464 | u64 amount = 0, min_amount, expires; |
ec12cb7f PT |
3465 | |
3466 | /* note: this is a positive sum as runtime_remaining <= 0 */ | |
3467 | min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining; | |
3468 | ||
3469 | raw_spin_lock(&cfs_b->lock); | |
3470 | if (cfs_b->quota == RUNTIME_INF) | |
3471 | amount = min_amount; | |
58088ad0 | 3472 | else { |
a9cf55b2 PT |
3473 | /* |
3474 | * If the bandwidth pool has become inactive, then at least one | |
3475 | * period must have elapsed since the last consumption. | |
3476 | * Refresh the global state and ensure bandwidth timer becomes | |
3477 | * active. | |
3478 | */ | |
3479 | if (!cfs_b->timer_active) { | |
3480 | __refill_cfs_bandwidth_runtime(cfs_b); | |
09dc4ab0 | 3481 | __start_cfs_bandwidth(cfs_b, false); |
a9cf55b2 | 3482 | } |
58088ad0 PT |
3483 | |
3484 | if (cfs_b->runtime > 0) { | |
3485 | amount = min(cfs_b->runtime, min_amount); | |
3486 | cfs_b->runtime -= amount; | |
3487 | cfs_b->idle = 0; | |
3488 | } | |
ec12cb7f | 3489 | } |
a9cf55b2 | 3490 | expires = cfs_b->runtime_expires; |
ec12cb7f PT |
3491 | raw_spin_unlock(&cfs_b->lock); |
3492 | ||
3493 | cfs_rq->runtime_remaining += amount; | |
a9cf55b2 PT |
3494 | /* |
3495 | * we may have advanced our local expiration to account for allowed | |
3496 | * spread between our sched_clock and the one on which runtime was | |
3497 | * issued. | |
3498 | */ | |
3499 | if ((s64)(expires - cfs_rq->runtime_expires) > 0) | |
3500 | cfs_rq->runtime_expires = expires; | |
85dac906 PT |
3501 | |
3502 | return cfs_rq->runtime_remaining > 0; | |
ec12cb7f PT |
3503 | } |
3504 | ||
a9cf55b2 PT |
3505 | /* |
3506 | * Note: This depends on the synchronization provided by sched_clock and the | |
3507 | * fact that rq->clock snapshots this value. | |
3508 | */ | |
3509 | static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
ec12cb7f | 3510 | { |
a9cf55b2 | 3511 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
a9cf55b2 PT |
3512 | |
3513 | /* if the deadline is ahead of our clock, nothing to do */ | |
78becc27 | 3514 | if (likely((s64)(rq_clock(rq_of(cfs_rq)) - cfs_rq->runtime_expires) < 0)) |
ec12cb7f PT |
3515 | return; |
3516 | ||
a9cf55b2 PT |
3517 | if (cfs_rq->runtime_remaining < 0) |
3518 | return; | |
3519 | ||
3520 | /* | |
3521 | * If the local deadline has passed we have to consider the | |
3522 | * possibility that our sched_clock is 'fast' and the global deadline | |
3523 | * has not truly expired. | |
3524 | * | |
3525 | * Fortunately we can check determine whether this the case by checking | |
51f2176d BS |
3526 | * whether the global deadline has advanced. It is valid to compare |
3527 | * cfs_b->runtime_expires without any locks since we only care about | |
3528 | * exact equality, so a partial write will still work. | |
a9cf55b2 PT |
3529 | */ |
3530 | ||
51f2176d | 3531 | if (cfs_rq->runtime_expires != cfs_b->runtime_expires) { |
a9cf55b2 PT |
3532 | /* extend local deadline, drift is bounded above by 2 ticks */ |
3533 | cfs_rq->runtime_expires += TICK_NSEC; | |
3534 | } else { | |
3535 | /* global deadline is ahead, expiration has passed */ | |
3536 | cfs_rq->runtime_remaining = 0; | |
3537 | } | |
3538 | } | |
3539 | ||
9dbdb155 | 3540 | static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
a9cf55b2 PT |
3541 | { |
3542 | /* dock delta_exec before expiring quota (as it could span periods) */ | |
ec12cb7f | 3543 | cfs_rq->runtime_remaining -= delta_exec; |
a9cf55b2 PT |
3544 | expire_cfs_rq_runtime(cfs_rq); |
3545 | ||
3546 | if (likely(cfs_rq->runtime_remaining > 0)) | |
ec12cb7f PT |
3547 | return; |
3548 | ||
85dac906 PT |
3549 | /* |
3550 | * if we're unable to extend our runtime we resched so that the active | |
3551 | * hierarchy can be throttled | |
3552 | */ | |
3553 | if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr)) | |
8875125e | 3554 | resched_curr(rq_of(cfs_rq)); |
ec12cb7f PT |
3555 | } |
3556 | ||
6c16a6dc | 3557 | static __always_inline |
9dbdb155 | 3558 | void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
ec12cb7f | 3559 | { |
56f570e5 | 3560 | if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled) |
ec12cb7f PT |
3561 | return; |
3562 | ||
3563 | __account_cfs_rq_runtime(cfs_rq, delta_exec); | |
3564 | } | |
3565 | ||
85dac906 PT |
3566 | static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) |
3567 | { | |
56f570e5 | 3568 | return cfs_bandwidth_used() && cfs_rq->throttled; |
85dac906 PT |
3569 | } |
3570 | ||
64660c86 PT |
3571 | /* check whether cfs_rq, or any parent, is throttled */ |
3572 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) | |
3573 | { | |
56f570e5 | 3574 | return cfs_bandwidth_used() && cfs_rq->throttle_count; |
64660c86 PT |
3575 | } |
3576 | ||
3577 | /* | |
3578 | * Ensure that neither of the group entities corresponding to src_cpu or | |
3579 | * dest_cpu are members of a throttled hierarchy when performing group | |
3580 | * load-balance operations. | |
3581 | */ | |
3582 | static inline int throttled_lb_pair(struct task_group *tg, | |
3583 | int src_cpu, int dest_cpu) | |
3584 | { | |
3585 | struct cfs_rq *src_cfs_rq, *dest_cfs_rq; | |
3586 | ||
3587 | src_cfs_rq = tg->cfs_rq[src_cpu]; | |
3588 | dest_cfs_rq = tg->cfs_rq[dest_cpu]; | |
3589 | ||
3590 | return throttled_hierarchy(src_cfs_rq) || | |
3591 | throttled_hierarchy(dest_cfs_rq); | |
3592 | } | |
3593 | ||
3594 | /* updated child weight may affect parent so we have to do this bottom up */ | |
3595 | static int tg_unthrottle_up(struct task_group *tg, void *data) | |
3596 | { | |
3597 | struct rq *rq = data; | |
3598 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; | |
3599 | ||
3600 | cfs_rq->throttle_count--; | |
3601 | #ifdef CONFIG_SMP | |
3602 | if (!cfs_rq->throttle_count) { | |
f1b17280 | 3603 | /* adjust cfs_rq_clock_task() */ |
78becc27 | 3604 | cfs_rq->throttled_clock_task_time += rq_clock_task(rq) - |
f1b17280 | 3605 | cfs_rq->throttled_clock_task; |
64660c86 PT |
3606 | } |
3607 | #endif | |
3608 | ||
3609 | return 0; | |
3610 | } | |
3611 | ||
3612 | static int tg_throttle_down(struct task_group *tg, void *data) | |
3613 | { | |
3614 | struct rq *rq = data; | |
3615 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; | |
3616 | ||
82958366 PT |
3617 | /* group is entering throttled state, stop time */ |
3618 | if (!cfs_rq->throttle_count) | |
78becc27 | 3619 | cfs_rq->throttled_clock_task = rq_clock_task(rq); |
64660c86 PT |
3620 | cfs_rq->throttle_count++; |
3621 | ||
3622 | return 0; | |
3623 | } | |
3624 | ||
d3d9dc33 | 3625 | static void throttle_cfs_rq(struct cfs_rq *cfs_rq) |
85dac906 PT |
3626 | { |
3627 | struct rq *rq = rq_of(cfs_rq); | |
3628 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
3629 | struct sched_entity *se; | |
3630 | long task_delta, dequeue = 1; | |
3631 | ||
3632 | se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; | |
3633 | ||
f1b17280 | 3634 | /* freeze hierarchy runnable averages while throttled */ |
64660c86 PT |
3635 | rcu_read_lock(); |
3636 | walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq); | |
3637 | rcu_read_unlock(); | |
85dac906 PT |
3638 | |
3639 | task_delta = cfs_rq->h_nr_running; | |
3640 | for_each_sched_entity(se) { | |
3641 | struct cfs_rq *qcfs_rq = cfs_rq_of(se); | |
3642 | /* throttled entity or throttle-on-deactivate */ | |
3643 | if (!se->on_rq) | |
3644 | break; | |
3645 | ||
3646 | if (dequeue) | |
3647 | dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP); | |
3648 | qcfs_rq->h_nr_running -= task_delta; | |
3649 | ||
3650 | if (qcfs_rq->load.weight) | |
3651 | dequeue = 0; | |
3652 | } | |
3653 | ||
3654 | if (!se) | |
72465447 | 3655 | sub_nr_running(rq, task_delta); |
85dac906 PT |
3656 | |
3657 | cfs_rq->throttled = 1; | |
78becc27 | 3658 | cfs_rq->throttled_clock = rq_clock(rq); |
85dac906 | 3659 | raw_spin_lock(&cfs_b->lock); |
c06f04c7 BS |
3660 | /* |
3661 | * Add to the _head_ of the list, so that an already-started | |
3662 | * distribute_cfs_runtime will not see us | |
3663 | */ | |
3664 | list_add_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq); | |
f9f9ffc2 | 3665 | if (!cfs_b->timer_active) |
09dc4ab0 | 3666 | __start_cfs_bandwidth(cfs_b, false); |
85dac906 PT |
3667 | raw_spin_unlock(&cfs_b->lock); |
3668 | } | |
3669 | ||
029632fb | 3670 | void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) |
671fd9da PT |
3671 | { |
3672 | struct rq *rq = rq_of(cfs_rq); | |
3673 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
3674 | struct sched_entity *se; | |
3675 | int enqueue = 1; | |
3676 | long task_delta; | |
3677 | ||
22b958d8 | 3678 | se = cfs_rq->tg->se[cpu_of(rq)]; |
671fd9da PT |
3679 | |
3680 | cfs_rq->throttled = 0; | |
1a55af2e FW |
3681 | |
3682 | update_rq_clock(rq); | |
3683 | ||
671fd9da | 3684 | raw_spin_lock(&cfs_b->lock); |
78becc27 | 3685 | cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock; |
671fd9da PT |
3686 | list_del_rcu(&cfs_rq->throttled_list); |
3687 | raw_spin_unlock(&cfs_b->lock); | |
3688 | ||
64660c86 PT |
3689 | /* update hierarchical throttle state */ |
3690 | walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq); | |
3691 | ||
671fd9da PT |
3692 | if (!cfs_rq->load.weight) |
3693 | return; | |
3694 | ||
3695 | task_delta = cfs_rq->h_nr_running; | |
3696 | for_each_sched_entity(se) { | |
3697 | if (se->on_rq) | |
3698 | enqueue = 0; | |
3699 | ||
3700 | cfs_rq = cfs_rq_of(se); | |
3701 | if (enqueue) | |
3702 | enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP); | |
3703 | cfs_rq->h_nr_running += task_delta; | |
3704 | ||
3705 | if (cfs_rq_throttled(cfs_rq)) | |
3706 | break; | |
3707 | } | |
3708 | ||
3709 | if (!se) | |
72465447 | 3710 | add_nr_running(rq, task_delta); |
671fd9da PT |
3711 | |
3712 | /* determine whether we need to wake up potentially idle cpu */ | |
3713 | if (rq->curr == rq->idle && rq->cfs.nr_running) | |
8875125e | 3714 | resched_curr(rq); |
671fd9da PT |
3715 | } |
3716 | ||
3717 | static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, | |
3718 | u64 remaining, u64 expires) | |
3719 | { | |
3720 | struct cfs_rq *cfs_rq; | |
c06f04c7 BS |
3721 | u64 runtime; |
3722 | u64 starting_runtime = remaining; | |
671fd9da PT |
3723 | |
3724 | rcu_read_lock(); | |
3725 | list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq, | |
3726 | throttled_list) { | |
3727 | struct rq *rq = rq_of(cfs_rq); | |
3728 | ||
3729 | raw_spin_lock(&rq->lock); | |
3730 | if (!cfs_rq_throttled(cfs_rq)) | |
3731 | goto next; | |
3732 | ||
3733 | runtime = -cfs_rq->runtime_remaining + 1; | |
3734 | if (runtime > remaining) | |
3735 | runtime = remaining; | |
3736 | remaining -= runtime; | |
3737 | ||
3738 | cfs_rq->runtime_remaining += runtime; | |
3739 | cfs_rq->runtime_expires = expires; | |
3740 | ||
3741 | /* we check whether we're throttled above */ | |
3742 | if (cfs_rq->runtime_remaining > 0) | |
3743 | unthrottle_cfs_rq(cfs_rq); | |
3744 | ||
3745 | next: | |
3746 | raw_spin_unlock(&rq->lock); | |
3747 | ||
3748 | if (!remaining) | |
3749 | break; | |
3750 | } | |
3751 | rcu_read_unlock(); | |
3752 | ||
c06f04c7 | 3753 | return starting_runtime - remaining; |
671fd9da PT |
3754 | } |
3755 | ||
58088ad0 PT |
3756 | /* |
3757 | * Responsible for refilling a task_group's bandwidth and unthrottling its | |
3758 | * cfs_rqs as appropriate. If there has been no activity within the last | |
3759 | * period the timer is deactivated until scheduling resumes; cfs_b->idle is | |
3760 | * used to track this state. | |
3761 | */ | |
3762 | static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) | |
3763 | { | |
671fd9da | 3764 | u64 runtime, runtime_expires; |
51f2176d | 3765 | int throttled; |
58088ad0 | 3766 | |
58088ad0 PT |
3767 | /* no need to continue the timer with no bandwidth constraint */ |
3768 | if (cfs_b->quota == RUNTIME_INF) | |
51f2176d | 3769 | goto out_deactivate; |
58088ad0 | 3770 | |
671fd9da | 3771 | throttled = !list_empty(&cfs_b->throttled_cfs_rq); |
e8da1b18 | 3772 | cfs_b->nr_periods += overrun; |
671fd9da | 3773 | |
51f2176d BS |
3774 | /* |
3775 | * idle depends on !throttled (for the case of a large deficit), and if | |
3776 | * we're going inactive then everything else can be deferred | |
3777 | */ | |
3778 | if (cfs_b->idle && !throttled) | |
3779 | goto out_deactivate; | |
a9cf55b2 | 3780 | |
927b54fc BS |
3781 | /* |
3782 | * if we have relooped after returning idle once, we need to update our | |
3783 | * status as actually running, so that other cpus doing | |
3784 | * __start_cfs_bandwidth will stop trying to cancel us. | |
3785 | */ | |
3786 | cfs_b->timer_active = 1; | |
3787 | ||
a9cf55b2 PT |
3788 | __refill_cfs_bandwidth_runtime(cfs_b); |
3789 | ||
671fd9da PT |
3790 | if (!throttled) { |
3791 | /* mark as potentially idle for the upcoming period */ | |
3792 | cfs_b->idle = 1; | |
51f2176d | 3793 | return 0; |
671fd9da PT |
3794 | } |
3795 | ||
e8da1b18 NR |
3796 | /* account preceding periods in which throttling occurred */ |
3797 | cfs_b->nr_throttled += overrun; | |
3798 | ||
671fd9da | 3799 | runtime_expires = cfs_b->runtime_expires; |
671fd9da PT |
3800 | |
3801 | /* | |
c06f04c7 BS |
3802 | * This check is repeated as we are holding onto the new bandwidth while |
3803 | * we unthrottle. This can potentially race with an unthrottled group | |
3804 | * trying to acquire new bandwidth from the global pool. This can result | |
3805 | * in us over-using our runtime if it is all used during this loop, but | |
3806 | * only by limited amounts in that extreme case. | |
671fd9da | 3807 | */ |
c06f04c7 BS |
3808 | while (throttled && cfs_b->runtime > 0) { |
3809 | runtime = cfs_b->runtime; | |
671fd9da PT |
3810 | raw_spin_unlock(&cfs_b->lock); |
3811 | /* we can't nest cfs_b->lock while distributing bandwidth */ | |
3812 | runtime = distribute_cfs_runtime(cfs_b, runtime, | |
3813 | runtime_expires); | |
3814 | raw_spin_lock(&cfs_b->lock); | |
3815 | ||
3816 | throttled = !list_empty(&cfs_b->throttled_cfs_rq); | |
c06f04c7 BS |
3817 | |
3818 | cfs_b->runtime -= min(runtime, cfs_b->runtime); | |
671fd9da | 3819 | } |
58088ad0 | 3820 | |
671fd9da PT |
3821 | /* |
3822 | * While we are ensured activity in the period following an | |
3823 | * unthrottle, this also covers the case in which the new bandwidth is | |
3824 | * insufficient to cover the existing bandwidth deficit. (Forcing the | |
3825 | * timer to remain active while there are any throttled entities.) | |
3826 | */ | |
3827 | cfs_b->idle = 0; | |
58088ad0 | 3828 | |
51f2176d BS |
3829 | return 0; |
3830 | ||
3831 | out_deactivate: | |
3832 | cfs_b->timer_active = 0; | |
3833 | return 1; | |
58088ad0 | 3834 | } |
d3d9dc33 | 3835 | |
d8b4986d PT |
3836 | /* a cfs_rq won't donate quota below this amount */ |
3837 | static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC; | |
3838 | /* minimum remaining period time to redistribute slack quota */ | |
3839 | static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC; | |
3840 | /* how long we wait to gather additional slack before distributing */ | |
3841 | static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC; | |
3842 | ||
db06e78c BS |
3843 | /* |
3844 | * Are we near the end of the current quota period? | |
3845 | * | |
3846 | * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the | |
3847 | * hrtimer base being cleared by __hrtimer_start_range_ns. In the case of | |
3848 | * migrate_hrtimers, base is never cleared, so we are fine. | |
3849 | */ | |
d8b4986d PT |
3850 | static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) |
3851 | { | |
3852 | struct hrtimer *refresh_timer = &cfs_b->period_timer; | |
3853 | u64 remaining; | |
3854 | ||
3855 | /* if the call-back is running a quota refresh is already occurring */ | |
3856 | if (hrtimer_callback_running(refresh_timer)) | |
3857 | return 1; | |
3858 | ||
3859 | /* is a quota refresh about to occur? */ | |
3860 | remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer)); | |
3861 | if (remaining < min_expire) | |
3862 | return 1; | |
3863 | ||
3864 | return 0; | |
3865 | } | |
3866 | ||
3867 | static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b) | |
3868 | { | |
3869 | u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration; | |
3870 | ||
3871 | /* if there's a quota refresh soon don't bother with slack */ | |
3872 | if (runtime_refresh_within(cfs_b, min_left)) | |
3873 | return; | |
3874 | ||
3875 | start_bandwidth_timer(&cfs_b->slack_timer, | |
3876 | ns_to_ktime(cfs_bandwidth_slack_period)); | |
3877 | } | |
3878 | ||
3879 | /* we know any runtime found here is valid as update_curr() precedes return */ | |
3880 | static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
3881 | { | |
3882 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
3883 | s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime; | |
3884 | ||
3885 | if (slack_runtime <= 0) | |
3886 | return; | |
3887 | ||
3888 | raw_spin_lock(&cfs_b->lock); | |
3889 | if (cfs_b->quota != RUNTIME_INF && | |
3890 | cfs_rq->runtime_expires == cfs_b->runtime_expires) { | |
3891 | cfs_b->runtime += slack_runtime; | |
3892 | ||
3893 | /* we are under rq->lock, defer unthrottling using a timer */ | |
3894 | if (cfs_b->runtime > sched_cfs_bandwidth_slice() && | |
3895 | !list_empty(&cfs_b->throttled_cfs_rq)) | |
3896 | start_cfs_slack_bandwidth(cfs_b); | |
3897 | } | |
3898 | raw_spin_unlock(&cfs_b->lock); | |
3899 | ||
3900 | /* even if it's not valid for return we don't want to try again */ | |
3901 | cfs_rq->runtime_remaining -= slack_runtime; | |
3902 | } | |
3903 | ||
3904 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
3905 | { | |
56f570e5 PT |
3906 | if (!cfs_bandwidth_used()) |
3907 | return; | |
3908 | ||
fccfdc6f | 3909 | if (!cfs_rq->runtime_enabled || cfs_rq->nr_running) |
d8b4986d PT |
3910 | return; |
3911 | ||
3912 | __return_cfs_rq_runtime(cfs_rq); | |
3913 | } | |
3914 | ||
3915 | /* | |
3916 | * This is done with a timer (instead of inline with bandwidth return) since | |
3917 | * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs. | |
3918 | */ | |
3919 | static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b) | |
3920 | { | |
3921 | u64 runtime = 0, slice = sched_cfs_bandwidth_slice(); | |
3922 | u64 expires; | |
3923 | ||
3924 | /* confirm we're still not at a refresh boundary */ | |
db06e78c BS |
3925 | raw_spin_lock(&cfs_b->lock); |
3926 | if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) { | |
3927 | raw_spin_unlock(&cfs_b->lock); | |
d8b4986d | 3928 | return; |
db06e78c | 3929 | } |
d8b4986d | 3930 | |
c06f04c7 | 3931 | if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) |
d8b4986d | 3932 | runtime = cfs_b->runtime; |
c06f04c7 | 3933 | |
d8b4986d PT |
3934 | expires = cfs_b->runtime_expires; |
3935 | raw_spin_unlock(&cfs_b->lock); | |
3936 | ||
3937 | if (!runtime) | |
3938 | return; | |
3939 | ||
3940 | runtime = distribute_cfs_runtime(cfs_b, runtime, expires); | |
3941 | ||
3942 | raw_spin_lock(&cfs_b->lock); | |
3943 | if (expires == cfs_b->runtime_expires) | |
c06f04c7 | 3944 | cfs_b->runtime -= min(runtime, cfs_b->runtime); |
d8b4986d PT |
3945 | raw_spin_unlock(&cfs_b->lock); |
3946 | } | |
3947 | ||
d3d9dc33 PT |
3948 | /* |
3949 | * When a group wakes up we want to make sure that its quota is not already | |
3950 | * expired/exceeded, otherwise it may be allowed to steal additional ticks of | |
3951 | * runtime as update_curr() throttling can not not trigger until it's on-rq. | |
3952 | */ | |
3953 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq) | |
3954 | { | |
56f570e5 PT |
3955 | if (!cfs_bandwidth_used()) |
3956 | return; | |
3957 | ||
d3d9dc33 PT |
3958 | /* an active group must be handled by the update_curr()->put() path */ |
3959 | if (!cfs_rq->runtime_enabled || cfs_rq->curr) | |
3960 | return; | |
3961 | ||
3962 | /* ensure the group is not already throttled */ | |
3963 | if (cfs_rq_throttled(cfs_rq)) | |
3964 | return; | |
3965 | ||
3966 | /* update runtime allocation */ | |
3967 | account_cfs_rq_runtime(cfs_rq, 0); | |
3968 | if (cfs_rq->runtime_remaining <= 0) | |
3969 | throttle_cfs_rq(cfs_rq); | |
3970 | } | |
3971 | ||
3972 | /* conditionally throttle active cfs_rq's from put_prev_entity() */ | |
678d5718 | 3973 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
d3d9dc33 | 3974 | { |
56f570e5 | 3975 | if (!cfs_bandwidth_used()) |
678d5718 | 3976 | return false; |
56f570e5 | 3977 | |
d3d9dc33 | 3978 | if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0)) |
678d5718 | 3979 | return false; |
d3d9dc33 PT |
3980 | |
3981 | /* | |
3982 | * it's possible for a throttled entity to be forced into a running | |
3983 | * state (e.g. set_curr_task), in this case we're finished. | |
3984 | */ | |
3985 | if (cfs_rq_throttled(cfs_rq)) | |
678d5718 | 3986 | return true; |
d3d9dc33 PT |
3987 | |
3988 | throttle_cfs_rq(cfs_rq); | |
678d5718 | 3989 | return true; |
d3d9dc33 | 3990 | } |
029632fb | 3991 | |
029632fb PZ |
3992 | static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer) |
3993 | { | |
3994 | struct cfs_bandwidth *cfs_b = | |
3995 | container_of(timer, struct cfs_bandwidth, slack_timer); | |
3996 | do_sched_cfs_slack_timer(cfs_b); | |
3997 | ||
3998 | return HRTIMER_NORESTART; | |
3999 | } | |
4000 | ||
4001 | static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) | |
4002 | { | |
4003 | struct cfs_bandwidth *cfs_b = | |
4004 | container_of(timer, struct cfs_bandwidth, period_timer); | |
4005 | ktime_t now; | |
4006 | int overrun; | |
4007 | int idle = 0; | |
4008 | ||
51f2176d | 4009 | raw_spin_lock(&cfs_b->lock); |
029632fb PZ |
4010 | for (;;) { |
4011 | now = hrtimer_cb_get_time(timer); | |
4012 | overrun = hrtimer_forward(timer, now, cfs_b->period); | |
4013 | ||
4014 | if (!overrun) | |
4015 | break; | |
4016 | ||
4017 | idle = do_sched_cfs_period_timer(cfs_b, overrun); | |
4018 | } | |
51f2176d | 4019 | raw_spin_unlock(&cfs_b->lock); |
029632fb PZ |
4020 | |
4021 | return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; | |
4022 | } | |
4023 | ||
4024 | void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) | |
4025 | { | |
4026 | raw_spin_lock_init(&cfs_b->lock); | |
4027 | cfs_b->runtime = 0; | |
4028 | cfs_b->quota = RUNTIME_INF; | |
4029 | cfs_b->period = ns_to_ktime(default_cfs_period()); | |
4030 | ||
4031 | INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq); | |
4032 | hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
4033 | cfs_b->period_timer.function = sched_cfs_period_timer; | |
4034 | hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
4035 | cfs_b->slack_timer.function = sched_cfs_slack_timer; | |
4036 | } | |
4037 | ||
4038 | static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
4039 | { | |
4040 | cfs_rq->runtime_enabled = 0; | |
4041 | INIT_LIST_HEAD(&cfs_rq->throttled_list); | |
4042 | } | |
4043 | ||
4044 | /* requires cfs_b->lock, may release to reprogram timer */ | |
09dc4ab0 | 4045 | void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b, bool force) |
029632fb PZ |
4046 | { |
4047 | /* | |
4048 | * The timer may be active because we're trying to set a new bandwidth | |
4049 | * period or because we're racing with the tear-down path | |
4050 | * (timer_active==0 becomes visible before the hrtimer call-back | |
4051 | * terminates). In either case we ensure that it's re-programmed | |
4052 | */ | |
927b54fc BS |
4053 | while (unlikely(hrtimer_active(&cfs_b->period_timer)) && |
4054 | hrtimer_try_to_cancel(&cfs_b->period_timer) < 0) { | |
4055 | /* bounce the lock to allow do_sched_cfs_period_timer to run */ | |
029632fb | 4056 | raw_spin_unlock(&cfs_b->lock); |
927b54fc | 4057 | cpu_relax(); |
029632fb PZ |
4058 | raw_spin_lock(&cfs_b->lock); |
4059 | /* if someone else restarted the timer then we're done */ | |
09dc4ab0 | 4060 | if (!force && cfs_b->timer_active) |
029632fb PZ |
4061 | return; |
4062 | } | |
4063 | ||
4064 | cfs_b->timer_active = 1; | |
4065 | start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period); | |
4066 | } | |
4067 | ||
4068 | static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) | |
4069 | { | |
7f1a169b TH |
4070 | /* init_cfs_bandwidth() was not called */ |
4071 | if (!cfs_b->throttled_cfs_rq.next) | |
4072 | return; | |
4073 | ||
029632fb PZ |
4074 | hrtimer_cancel(&cfs_b->period_timer); |
4075 | hrtimer_cancel(&cfs_b->slack_timer); | |
4076 | } | |
4077 | ||
0e59bdae KT |
4078 | static void __maybe_unused update_runtime_enabled(struct rq *rq) |
4079 | { | |
4080 | struct cfs_rq *cfs_rq; | |
4081 | ||
4082 | for_each_leaf_cfs_rq(rq, cfs_rq) { | |
4083 | struct cfs_bandwidth *cfs_b = &cfs_rq->tg->cfs_bandwidth; | |
4084 | ||
4085 | raw_spin_lock(&cfs_b->lock); | |
4086 | cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; | |
4087 | raw_spin_unlock(&cfs_b->lock); | |
4088 | } | |
4089 | } | |
4090 | ||
38dc3348 | 4091 | static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq) |
029632fb PZ |
4092 | { |
4093 | struct cfs_rq *cfs_rq; | |
4094 | ||
4095 | for_each_leaf_cfs_rq(rq, cfs_rq) { | |
029632fb PZ |
4096 | if (!cfs_rq->runtime_enabled) |
4097 | continue; | |
4098 | ||
4099 | /* | |
4100 | * clock_task is not advancing so we just need to make sure | |
4101 | * there's some valid quota amount | |
4102 | */ | |
51f2176d | 4103 | cfs_rq->runtime_remaining = 1; |
0e59bdae KT |
4104 | /* |
4105 | * Offline rq is schedulable till cpu is completely disabled | |
4106 | * in take_cpu_down(), so we prevent new cfs throttling here. | |
4107 | */ | |
4108 | cfs_rq->runtime_enabled = 0; | |
4109 | ||
029632fb PZ |
4110 | if (cfs_rq_throttled(cfs_rq)) |
4111 | unthrottle_cfs_rq(cfs_rq); | |
4112 | } | |
4113 | } | |
4114 | ||
4115 | #else /* CONFIG_CFS_BANDWIDTH */ | |
f1b17280 PT |
4116 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) |
4117 | { | |
78becc27 | 4118 | return rq_clock_task(rq_of(cfs_rq)); |
f1b17280 PT |
4119 | } |
4120 | ||
9dbdb155 | 4121 | static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {} |
678d5718 | 4122 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; } |
d3d9dc33 | 4123 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {} |
6c16a6dc | 4124 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} |
85dac906 PT |
4125 | |
4126 | static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) | |
4127 | { | |
4128 | return 0; | |
4129 | } | |
64660c86 PT |
4130 | |
4131 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) | |
4132 | { | |
4133 | return 0; | |
4134 | } | |
4135 | ||
4136 | static inline int throttled_lb_pair(struct task_group *tg, | |
4137 | int src_cpu, int dest_cpu) | |
4138 | { | |
4139 | return 0; | |
4140 | } | |
029632fb PZ |
4141 | |
4142 | void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} | |
4143 | ||
4144 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
4145 | static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} | |
ab84d31e PT |
4146 | #endif |
4147 | ||
029632fb PZ |
4148 | static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
4149 | { | |
4150 | return NULL; | |
4151 | } | |
4152 | static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} | |
0e59bdae | 4153 | static inline void update_runtime_enabled(struct rq *rq) {} |
a4c96ae3 | 4154 | static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {} |
029632fb PZ |
4155 | |
4156 | #endif /* CONFIG_CFS_BANDWIDTH */ | |
4157 | ||
bf0f6f24 IM |
4158 | /************************************************** |
4159 | * CFS operations on tasks: | |
4160 | */ | |
4161 | ||
8f4d37ec PZ |
4162 | #ifdef CONFIG_SCHED_HRTICK |
4163 | static void hrtick_start_fair(struct rq *rq, struct task_struct *p) | |
4164 | { | |
8f4d37ec PZ |
4165 | struct sched_entity *se = &p->se; |
4166 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
4167 | ||
4168 | WARN_ON(task_rq(p) != rq); | |
4169 | ||
b39e66ea | 4170 | if (cfs_rq->nr_running > 1) { |
8f4d37ec PZ |
4171 | u64 slice = sched_slice(cfs_rq, se); |
4172 | u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime; | |
4173 | s64 delta = slice - ran; | |
4174 | ||
4175 | if (delta < 0) { | |
4176 | if (rq->curr == p) | |
8875125e | 4177 | resched_curr(rq); |
8f4d37ec PZ |
4178 | return; |
4179 | } | |
31656519 | 4180 | hrtick_start(rq, delta); |
8f4d37ec PZ |
4181 | } |
4182 | } | |
a4c2f00f PZ |
4183 | |
4184 | /* | |
4185 | * called from enqueue/dequeue and updates the hrtick when the | |
4186 | * current task is from our class and nr_running is low enough | |
4187 | * to matter. | |
4188 | */ | |
4189 | static void hrtick_update(struct rq *rq) | |
4190 | { | |
4191 | struct task_struct *curr = rq->curr; | |
4192 | ||
b39e66ea | 4193 | if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class) |
a4c2f00f PZ |
4194 | return; |
4195 | ||
4196 | if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency) | |
4197 | hrtick_start_fair(rq, curr); | |
4198 | } | |
55e12e5e | 4199 | #else /* !CONFIG_SCHED_HRTICK */ |
8f4d37ec PZ |
4200 | static inline void |
4201 | hrtick_start_fair(struct rq *rq, struct task_struct *p) | |
4202 | { | |
4203 | } | |
a4c2f00f PZ |
4204 | |
4205 | static inline void hrtick_update(struct rq *rq) | |
4206 | { | |
4207 | } | |
8f4d37ec PZ |
4208 | #endif |
4209 | ||
bf0f6f24 IM |
4210 | /* |
4211 | * The enqueue_task method is called before nr_running is | |
4212 | * increased. Here we update the fair scheduling stats and | |
4213 | * then put the task into the rbtree: | |
4214 | */ | |
ea87bb78 | 4215 | static void |
371fd7e7 | 4216 | enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
bf0f6f24 IM |
4217 | { |
4218 | struct cfs_rq *cfs_rq; | |
62fb1851 | 4219 | struct sched_entity *se = &p->se; |
bf0f6f24 IM |
4220 | |
4221 | for_each_sched_entity(se) { | |
62fb1851 | 4222 | if (se->on_rq) |
bf0f6f24 IM |
4223 | break; |
4224 | cfs_rq = cfs_rq_of(se); | |
88ec22d3 | 4225 | enqueue_entity(cfs_rq, se, flags); |
85dac906 PT |
4226 | |
4227 | /* | |
4228 | * end evaluation on encountering a throttled cfs_rq | |
4229 | * | |
4230 | * note: in the case of encountering a throttled cfs_rq we will | |
4231 | * post the final h_nr_running increment below. | |
4232 | */ | |
4233 | if (cfs_rq_throttled(cfs_rq)) | |
4234 | break; | |
953bfcd1 | 4235 | cfs_rq->h_nr_running++; |
85dac906 | 4236 | |
88ec22d3 | 4237 | flags = ENQUEUE_WAKEUP; |
bf0f6f24 | 4238 | } |
8f4d37ec | 4239 | |
2069dd75 | 4240 | for_each_sched_entity(se) { |
0f317143 | 4241 | cfs_rq = cfs_rq_of(se); |
953bfcd1 | 4242 | cfs_rq->h_nr_running++; |
2069dd75 | 4243 | |
85dac906 PT |
4244 | if (cfs_rq_throttled(cfs_rq)) |
4245 | break; | |
4246 | ||
17bc14b7 | 4247 | update_cfs_shares(cfs_rq); |
9ee474f5 | 4248 | update_entity_load_avg(se, 1); |
2069dd75 PZ |
4249 | } |
4250 | ||
18bf2805 BS |
4251 | if (!se) { |
4252 | update_rq_runnable_avg(rq, rq->nr_running); | |
72465447 | 4253 | add_nr_running(rq, 1); |
18bf2805 | 4254 | } |
a4c2f00f | 4255 | hrtick_update(rq); |
bf0f6f24 IM |
4256 | } |
4257 | ||
2f36825b VP |
4258 | static void set_next_buddy(struct sched_entity *se); |
4259 | ||
bf0f6f24 IM |
4260 | /* |
4261 | * The dequeue_task method is called before nr_running is | |
4262 | * decreased. We remove the task from the rbtree and | |
4263 | * update the fair scheduling stats: | |
4264 | */ | |
371fd7e7 | 4265 | static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
bf0f6f24 IM |
4266 | { |
4267 | struct cfs_rq *cfs_rq; | |
62fb1851 | 4268 | struct sched_entity *se = &p->se; |
2f36825b | 4269 | int task_sleep = flags & DEQUEUE_SLEEP; |
bf0f6f24 IM |
4270 | |
4271 | for_each_sched_entity(se) { | |
4272 | cfs_rq = cfs_rq_of(se); | |
371fd7e7 | 4273 | dequeue_entity(cfs_rq, se, flags); |
85dac906 PT |
4274 | |
4275 | /* | |
4276 | * end evaluation on encountering a throttled cfs_rq | |
4277 | * | |
4278 | * note: in the case of encountering a throttled cfs_rq we will | |
4279 | * post the final h_nr_running decrement below. | |
4280 | */ | |
4281 | if (cfs_rq_throttled(cfs_rq)) | |
4282 | break; | |
953bfcd1 | 4283 | cfs_rq->h_nr_running--; |
2069dd75 | 4284 | |
bf0f6f24 | 4285 | /* Don't dequeue parent if it has other entities besides us */ |
2f36825b VP |
4286 | if (cfs_rq->load.weight) { |
4287 | /* | |
4288 | * Bias pick_next to pick a task from this cfs_rq, as | |
4289 | * p is sleeping when it is within its sched_slice. | |
4290 | */ | |
4291 | if (task_sleep && parent_entity(se)) | |
4292 | set_next_buddy(parent_entity(se)); | |
9598c82d PT |
4293 | |
4294 | /* avoid re-evaluating load for this entity */ | |
4295 | se = parent_entity(se); | |
bf0f6f24 | 4296 | break; |
2f36825b | 4297 | } |
371fd7e7 | 4298 | flags |= DEQUEUE_SLEEP; |
bf0f6f24 | 4299 | } |
8f4d37ec | 4300 | |
2069dd75 | 4301 | for_each_sched_entity(se) { |
0f317143 | 4302 | cfs_rq = cfs_rq_of(se); |
953bfcd1 | 4303 | cfs_rq->h_nr_running--; |
2069dd75 | 4304 | |
85dac906 PT |
4305 | if (cfs_rq_throttled(cfs_rq)) |
4306 | break; | |
4307 | ||
17bc14b7 | 4308 | update_cfs_shares(cfs_rq); |
9ee474f5 | 4309 | update_entity_load_avg(se, 1); |
2069dd75 PZ |
4310 | } |
4311 | ||
18bf2805 | 4312 | if (!se) { |
72465447 | 4313 | sub_nr_running(rq, 1); |
18bf2805 BS |
4314 | update_rq_runnable_avg(rq, 1); |
4315 | } | |
a4c2f00f | 4316 | hrtick_update(rq); |
bf0f6f24 IM |
4317 | } |
4318 | ||
e7693a36 | 4319 | #ifdef CONFIG_SMP |
029632fb PZ |
4320 | /* Used instead of source_load when we know the type == 0 */ |
4321 | static unsigned long weighted_cpuload(const int cpu) | |
4322 | { | |
b92486cb | 4323 | return cpu_rq(cpu)->cfs.runnable_load_avg; |
029632fb PZ |
4324 | } |
4325 | ||
4326 | /* | |
4327 | * Return a low guess at the load of a migration-source cpu weighted | |
4328 | * according to the scheduling class and "nice" value. | |
4329 | * | |
4330 | * We want to under-estimate the load of migration sources, to | |
4331 | * balance conservatively. | |
4332 | */ | |
4333 | static unsigned long source_load(int cpu, int type) | |
4334 | { | |
4335 | struct rq *rq = cpu_rq(cpu); | |
4336 | unsigned long total = weighted_cpuload(cpu); | |
4337 | ||
4338 | if (type == 0 || !sched_feat(LB_BIAS)) | |
4339 | return total; | |
4340 | ||
4341 | return min(rq->cpu_load[type-1], total); | |
4342 | } | |
4343 | ||
4344 | /* | |
4345 | * Return a high guess at the load of a migration-target cpu weighted | |
4346 | * according to the scheduling class and "nice" value. | |
4347 | */ | |
4348 | static unsigned long target_load(int cpu, int type) | |
4349 | { | |
4350 | struct rq *rq = cpu_rq(cpu); | |
4351 | unsigned long total = weighted_cpuload(cpu); | |
4352 | ||
4353 | if (type == 0 || !sched_feat(LB_BIAS)) | |
4354 | return total; | |
4355 | ||
4356 | return max(rq->cpu_load[type-1], total); | |
4357 | } | |
4358 | ||
ced549fa | 4359 | static unsigned long capacity_of(int cpu) |
029632fb | 4360 | { |
ced549fa | 4361 | return cpu_rq(cpu)->cpu_capacity; |
029632fb PZ |
4362 | } |
4363 | ||
ca6d75e6 VG |
4364 | static unsigned long capacity_orig_of(int cpu) |
4365 | { | |
4366 | return cpu_rq(cpu)->cpu_capacity_orig; | |
4367 | } | |
4368 | ||
029632fb PZ |
4369 | static unsigned long cpu_avg_load_per_task(int cpu) |
4370 | { | |
4371 | struct rq *rq = cpu_rq(cpu); | |
65fdac08 | 4372 | unsigned long nr_running = ACCESS_ONCE(rq->cfs.h_nr_running); |
b92486cb | 4373 | unsigned long load_avg = rq->cfs.runnable_load_avg; |
029632fb PZ |
4374 | |
4375 | if (nr_running) | |
b92486cb | 4376 | return load_avg / nr_running; |
029632fb PZ |
4377 | |
4378 | return 0; | |
4379 | } | |
4380 | ||
62470419 MW |
4381 | static void record_wakee(struct task_struct *p) |
4382 | { | |
4383 | /* | |
4384 | * Rough decay (wiping) for cost saving, don't worry | |
4385 | * about the boundary, really active task won't care | |
4386 | * about the loss. | |
4387 | */ | |
2538d960 | 4388 | if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) { |
096aa338 | 4389 | current->wakee_flips >>= 1; |
62470419 MW |
4390 | current->wakee_flip_decay_ts = jiffies; |
4391 | } | |
4392 | ||
4393 | if (current->last_wakee != p) { | |
4394 | current->last_wakee = p; | |
4395 | current->wakee_flips++; | |
4396 | } | |
4397 | } | |
098fb9db | 4398 | |
74f8e4b2 | 4399 | static void task_waking_fair(struct task_struct *p) |
88ec22d3 PZ |
4400 | { |
4401 | struct sched_entity *se = &p->se; | |
4402 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
3fe1698b PZ |
4403 | u64 min_vruntime; |
4404 | ||
4405 | #ifndef CONFIG_64BIT | |
4406 | u64 min_vruntime_copy; | |
88ec22d3 | 4407 | |
3fe1698b PZ |
4408 | do { |
4409 | min_vruntime_copy = cfs_rq->min_vruntime_copy; | |
4410 | smp_rmb(); | |
4411 | min_vruntime = cfs_rq->min_vruntime; | |
4412 | } while (min_vruntime != min_vruntime_copy); | |
4413 | #else | |
4414 | min_vruntime = cfs_rq->min_vruntime; | |
4415 | #endif | |
88ec22d3 | 4416 | |
3fe1698b | 4417 | se->vruntime -= min_vruntime; |
62470419 | 4418 | record_wakee(p); |
88ec22d3 PZ |
4419 | } |
4420 | ||
bb3469ac | 4421 | #ifdef CONFIG_FAIR_GROUP_SCHED |
f5bfb7d9 PZ |
4422 | /* |
4423 | * effective_load() calculates the load change as seen from the root_task_group | |
4424 | * | |
4425 | * Adding load to a group doesn't make a group heavier, but can cause movement | |
4426 | * of group shares between cpus. Assuming the shares were perfectly aligned one | |
4427 | * can calculate the shift in shares. | |
cf5f0acf PZ |
4428 | * |
4429 | * Calculate the effective load difference if @wl is added (subtracted) to @tg | |
4430 | * on this @cpu and results in a total addition (subtraction) of @wg to the | |
4431 | * total group weight. | |
4432 | * | |
4433 | * Given a runqueue weight distribution (rw_i) we can compute a shares | |
4434 | * distribution (s_i) using: | |
4435 | * | |
4436 | * s_i = rw_i / \Sum rw_j (1) | |
4437 | * | |
4438 | * Suppose we have 4 CPUs and our @tg is a direct child of the root group and | |
4439 | * has 7 equal weight tasks, distributed as below (rw_i), with the resulting | |
4440 | * shares distribution (s_i): | |
4441 | * | |
4442 | * rw_i = { 2, 4, 1, 0 } | |
4443 | * s_i = { 2/7, 4/7, 1/7, 0 } | |
4444 | * | |
4445 | * As per wake_affine() we're interested in the load of two CPUs (the CPU the | |
4446 | * task used to run on and the CPU the waker is running on), we need to | |
4447 | * compute the effect of waking a task on either CPU and, in case of a sync | |
4448 | * wakeup, compute the effect of the current task going to sleep. | |
4449 | * | |
4450 | * So for a change of @wl to the local @cpu with an overall group weight change | |
4451 | * of @wl we can compute the new shares distribution (s'_i) using: | |
4452 | * | |
4453 | * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2) | |
4454 | * | |
4455 | * Suppose we're interested in CPUs 0 and 1, and want to compute the load | |
4456 | * differences in waking a task to CPU 0. The additional task changes the | |
4457 | * weight and shares distributions like: | |
4458 | * | |
4459 | * rw'_i = { 3, 4, 1, 0 } | |
4460 | * s'_i = { 3/8, 4/8, 1/8, 0 } | |
4461 | * | |
4462 | * We can then compute the difference in effective weight by using: | |
4463 | * | |
4464 | * dw_i = S * (s'_i - s_i) (3) | |
4465 | * | |
4466 | * Where 'S' is the group weight as seen by its parent. | |
4467 | * | |
4468 | * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7) | |
4469 | * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 - | |
4470 | * 4/7) times the weight of the group. | |
f5bfb7d9 | 4471 | */ |
2069dd75 | 4472 | static long effective_load(struct task_group *tg, int cpu, long wl, long wg) |
bb3469ac | 4473 | { |
4be9daaa | 4474 | struct sched_entity *se = tg->se[cpu]; |
f1d239f7 | 4475 | |
9722c2da | 4476 | if (!tg->parent) /* the trivial, non-cgroup case */ |
f1d239f7 PZ |
4477 | return wl; |
4478 | ||
4be9daaa | 4479 | for_each_sched_entity(se) { |
cf5f0acf | 4480 | long w, W; |
4be9daaa | 4481 | |
977dda7c | 4482 | tg = se->my_q->tg; |
bb3469ac | 4483 | |
cf5f0acf PZ |
4484 | /* |
4485 | * W = @wg + \Sum rw_j | |
4486 | */ | |
4487 | W = wg + calc_tg_weight(tg, se->my_q); | |
4be9daaa | 4488 | |
cf5f0acf PZ |
4489 | /* |
4490 | * w = rw_i + @wl | |
4491 | */ | |
4492 | w = se->my_q->load.weight + wl; | |
940959e9 | 4493 | |
cf5f0acf PZ |
4494 | /* |
4495 | * wl = S * s'_i; see (2) | |
4496 | */ | |
4497 | if (W > 0 && w < W) | |
32a8df4e | 4498 | wl = (w * (long)tg->shares) / W; |
977dda7c PT |
4499 | else |
4500 | wl = tg->shares; | |
940959e9 | 4501 | |
cf5f0acf PZ |
4502 | /* |
4503 | * Per the above, wl is the new se->load.weight value; since | |
4504 | * those are clipped to [MIN_SHARES, ...) do so now. See | |
4505 | * calc_cfs_shares(). | |
4506 | */ | |
977dda7c PT |
4507 | if (wl < MIN_SHARES) |
4508 | wl = MIN_SHARES; | |
cf5f0acf PZ |
4509 | |
4510 | /* | |
4511 | * wl = dw_i = S * (s'_i - s_i); see (3) | |
4512 | */ | |
977dda7c | 4513 | wl -= se->load.weight; |
cf5f0acf PZ |
4514 | |
4515 | /* | |
4516 | * Recursively apply this logic to all parent groups to compute | |
4517 | * the final effective load change on the root group. Since | |
4518 | * only the @tg group gets extra weight, all parent groups can | |
4519 | * only redistribute existing shares. @wl is the shift in shares | |
4520 | * resulting from this level per the above. | |
4521 | */ | |
4be9daaa | 4522 | wg = 0; |
4be9daaa | 4523 | } |
bb3469ac | 4524 | |
4be9daaa | 4525 | return wl; |
bb3469ac PZ |
4526 | } |
4527 | #else | |
4be9daaa | 4528 | |
58d081b5 | 4529 | static long effective_load(struct task_group *tg, int cpu, long wl, long wg) |
4be9daaa | 4530 | { |
83378269 | 4531 | return wl; |
bb3469ac | 4532 | } |
4be9daaa | 4533 | |
bb3469ac PZ |
4534 | #endif |
4535 | ||
62470419 MW |
4536 | static int wake_wide(struct task_struct *p) |
4537 | { | |
7d9ffa89 | 4538 | int factor = this_cpu_read(sd_llc_size); |
62470419 MW |
4539 | |
4540 | /* | |
4541 | * Yeah, it's the switching-frequency, could means many wakee or | |
4542 | * rapidly switch, use factor here will just help to automatically | |
4543 | * adjust the loose-degree, so bigger node will lead to more pull. | |
4544 | */ | |
4545 | if (p->wakee_flips > factor) { | |
4546 | /* | |
4547 | * wakee is somewhat hot, it needs certain amount of cpu | |
4548 | * resource, so if waker is far more hot, prefer to leave | |
4549 | * it alone. | |
4550 | */ | |
4551 | if (current->wakee_flips > (factor * p->wakee_flips)) | |
4552 | return 1; | |
4553 | } | |
4554 | ||
4555 | return 0; | |
4556 | } | |
4557 | ||
c88d5910 | 4558 | static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) |
098fb9db | 4559 | { |
e37b6a7b | 4560 | s64 this_load, load; |
bd61c98f | 4561 | s64 this_eff_load, prev_eff_load; |
c88d5910 | 4562 | int idx, this_cpu, prev_cpu; |
c88d5910 | 4563 | struct task_group *tg; |
83378269 | 4564 | unsigned long weight; |
b3137bc8 | 4565 | int balanced; |
098fb9db | 4566 | |
62470419 MW |
4567 | /* |
4568 | * If we wake multiple tasks be careful to not bounce | |
4569 | * ourselves around too much. | |
4570 | */ | |
4571 | if (wake_wide(p)) | |
4572 | return 0; | |
4573 | ||
c88d5910 PZ |
4574 | idx = sd->wake_idx; |
4575 | this_cpu = smp_processor_id(); | |
4576 | prev_cpu = task_cpu(p); | |
4577 | load = source_load(prev_cpu, idx); | |
4578 | this_load = target_load(this_cpu, idx); | |
098fb9db | 4579 | |
b3137bc8 MG |
4580 | /* |
4581 | * If sync wakeup then subtract the (maximum possible) | |
4582 | * effect of the currently running task from the load | |
4583 | * of the current CPU: | |
4584 | */ | |
83378269 PZ |
4585 | if (sync) { |
4586 | tg = task_group(current); | |
4587 | weight = current->se.load.weight; | |
4588 | ||
c88d5910 | 4589 | this_load += effective_load(tg, this_cpu, -weight, -weight); |
83378269 PZ |
4590 | load += effective_load(tg, prev_cpu, 0, -weight); |
4591 | } | |
b3137bc8 | 4592 | |
83378269 PZ |
4593 | tg = task_group(p); |
4594 | weight = p->se.load.weight; | |
b3137bc8 | 4595 | |
71a29aa7 PZ |
4596 | /* |
4597 | * In low-load situations, where prev_cpu is idle and this_cpu is idle | |
c88d5910 PZ |
4598 | * due to the sync cause above having dropped this_load to 0, we'll |
4599 | * always have an imbalance, but there's really nothing you can do | |
4600 | * about that, so that's good too. | |
71a29aa7 PZ |
4601 | * |
4602 | * Otherwise check if either cpus are near enough in load to allow this | |
4603 | * task to be woken on this_cpu. | |
4604 | */ | |
bd61c98f VG |
4605 | this_eff_load = 100; |
4606 | this_eff_load *= capacity_of(prev_cpu); | |
e51fd5e2 | 4607 | |
bd61c98f VG |
4608 | prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2; |
4609 | prev_eff_load *= capacity_of(this_cpu); | |
e51fd5e2 | 4610 | |
bd61c98f | 4611 | if (this_load > 0) { |
e51fd5e2 PZ |
4612 | this_eff_load *= this_load + |
4613 | effective_load(tg, this_cpu, weight, weight); | |
4614 | ||
e51fd5e2 | 4615 | prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight); |
bd61c98f | 4616 | } |
e51fd5e2 | 4617 | |
bd61c98f | 4618 | balanced = this_eff_load <= prev_eff_load; |
098fb9db | 4619 | |
41acab88 | 4620 | schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts); |
098fb9db | 4621 | |
05bfb65f VG |
4622 | if (!balanced) |
4623 | return 0; | |
098fb9db | 4624 | |
05bfb65f VG |
4625 | schedstat_inc(sd, ttwu_move_affine); |
4626 | schedstat_inc(p, se.statistics.nr_wakeups_affine); | |
4627 | ||
4628 | return 1; | |
098fb9db IM |
4629 | } |
4630 | ||
aaee1203 PZ |
4631 | /* |
4632 | * find_idlest_group finds and returns the least busy CPU group within the | |
4633 | * domain. | |
4634 | */ | |
4635 | static struct sched_group * | |
78e7ed53 | 4636 | find_idlest_group(struct sched_domain *sd, struct task_struct *p, |
c44f2a02 | 4637 | int this_cpu, int sd_flag) |
e7693a36 | 4638 | { |
b3bd3de6 | 4639 | struct sched_group *idlest = NULL, *group = sd->groups; |
aaee1203 | 4640 | unsigned long min_load = ULONG_MAX, this_load = 0; |
c44f2a02 | 4641 | int load_idx = sd->forkexec_idx; |
aaee1203 | 4642 | int imbalance = 100 + (sd->imbalance_pct-100)/2; |
e7693a36 | 4643 | |
c44f2a02 VG |
4644 | if (sd_flag & SD_BALANCE_WAKE) |
4645 | load_idx = sd->wake_idx; | |
4646 | ||
aaee1203 PZ |
4647 | do { |
4648 | unsigned long load, avg_load; | |
4649 | int local_group; | |
4650 | int i; | |
e7693a36 | 4651 | |
aaee1203 PZ |
4652 | /* Skip over this group if it has no CPUs allowed */ |
4653 | if (!cpumask_intersects(sched_group_cpus(group), | |
fa17b507 | 4654 | tsk_cpus_allowed(p))) |
aaee1203 PZ |
4655 | continue; |
4656 | ||
4657 | local_group = cpumask_test_cpu(this_cpu, | |
4658 | sched_group_cpus(group)); | |
4659 | ||
4660 | /* Tally up the load of all CPUs in the group */ | |
4661 | avg_load = 0; | |
4662 | ||
4663 | for_each_cpu(i, sched_group_cpus(group)) { | |
4664 | /* Bias balancing toward cpus of our domain */ | |
4665 | if (local_group) | |
4666 | load = source_load(i, load_idx); | |
4667 | else | |
4668 | load = target_load(i, load_idx); | |
4669 | ||
4670 | avg_load += load; | |
4671 | } | |
4672 | ||
63b2ca30 | 4673 | /* Adjust by relative CPU capacity of the group */ |
ca8ce3d0 | 4674 | avg_load = (avg_load * SCHED_CAPACITY_SCALE) / group->sgc->capacity; |
aaee1203 PZ |
4675 | |
4676 | if (local_group) { | |
4677 | this_load = avg_load; | |
aaee1203 PZ |
4678 | } else if (avg_load < min_load) { |
4679 | min_load = avg_load; | |
4680 | idlest = group; | |
4681 | } | |
4682 | } while (group = group->next, group != sd->groups); | |
4683 | ||
4684 | if (!idlest || 100*this_load < imbalance*min_load) | |
4685 | return NULL; | |
4686 | return idlest; | |
4687 | } | |
4688 | ||
4689 | /* | |
4690 | * find_idlest_cpu - find the idlest cpu among the cpus in group. | |
4691 | */ | |
4692 | static int | |
4693 | find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) | |
4694 | { | |
4695 | unsigned long load, min_load = ULONG_MAX; | |
83a0a96a NP |
4696 | unsigned int min_exit_latency = UINT_MAX; |
4697 | u64 latest_idle_timestamp = 0; | |
4698 | int least_loaded_cpu = this_cpu; | |
4699 | int shallowest_idle_cpu = -1; | |
aaee1203 PZ |
4700 | int i; |
4701 | ||
4702 | /* Traverse only the allowed CPUs */ | |
fa17b507 | 4703 | for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) { |
83a0a96a NP |
4704 | if (idle_cpu(i)) { |
4705 | struct rq *rq = cpu_rq(i); | |
4706 | struct cpuidle_state *idle = idle_get_state(rq); | |
4707 | if (idle && idle->exit_latency < min_exit_latency) { | |
4708 | /* | |
4709 | * We give priority to a CPU whose idle state | |
4710 | * has the smallest exit latency irrespective | |
4711 | * of any idle timestamp. | |
4712 | */ | |
4713 | min_exit_latency = idle->exit_latency; | |
4714 | latest_idle_timestamp = rq->idle_stamp; | |
4715 | shallowest_idle_cpu = i; | |
4716 | } else if ((!idle || idle->exit_latency == min_exit_latency) && | |
4717 | rq->idle_stamp > latest_idle_timestamp) { | |
4718 | /* | |
4719 | * If equal or no active idle state, then | |
4720 | * the most recently idled CPU might have | |
4721 | * a warmer cache. | |
4722 | */ | |
4723 | latest_idle_timestamp = rq->idle_stamp; | |
4724 | shallowest_idle_cpu = i; | |
4725 | } | |
9f96742a | 4726 | } else if (shallowest_idle_cpu == -1) { |
83a0a96a NP |
4727 | load = weighted_cpuload(i); |
4728 | if (load < min_load || (load == min_load && i == this_cpu)) { | |
4729 | min_load = load; | |
4730 | least_loaded_cpu = i; | |
4731 | } | |
e7693a36 GH |
4732 | } |
4733 | } | |
4734 | ||
83a0a96a | 4735 | return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu; |
aaee1203 | 4736 | } |
e7693a36 | 4737 | |
a50bde51 PZ |
4738 | /* |
4739 | * Try and locate an idle CPU in the sched_domain. | |
4740 | */ | |
99bd5e2f | 4741 | static int select_idle_sibling(struct task_struct *p, int target) |
a50bde51 | 4742 | { |
99bd5e2f | 4743 | struct sched_domain *sd; |
37407ea7 | 4744 | struct sched_group *sg; |
e0a79f52 | 4745 | int i = task_cpu(p); |
a50bde51 | 4746 | |
e0a79f52 MG |
4747 | if (idle_cpu(target)) |
4748 | return target; | |
99bd5e2f SS |
4749 | |
4750 | /* | |
e0a79f52 | 4751 | * If the prevous cpu is cache affine and idle, don't be stupid. |
99bd5e2f | 4752 | */ |
e0a79f52 MG |
4753 | if (i != target && cpus_share_cache(i, target) && idle_cpu(i)) |
4754 | return i; | |
a50bde51 PZ |
4755 | |
4756 | /* | |
37407ea7 | 4757 | * Otherwise, iterate the domains and find an elegible idle cpu. |
a50bde51 | 4758 | */ |
518cd623 | 4759 | sd = rcu_dereference(per_cpu(sd_llc, target)); |
970e1789 | 4760 | for_each_lower_domain(sd) { |
37407ea7 LT |
4761 | sg = sd->groups; |
4762 | do { | |
4763 | if (!cpumask_intersects(sched_group_cpus(sg), | |
4764 | tsk_cpus_allowed(p))) | |
4765 | goto next; | |
4766 | ||
4767 | for_each_cpu(i, sched_group_cpus(sg)) { | |
e0a79f52 | 4768 | if (i == target || !idle_cpu(i)) |
37407ea7 LT |
4769 | goto next; |
4770 | } | |
970e1789 | 4771 | |
37407ea7 LT |
4772 | target = cpumask_first_and(sched_group_cpus(sg), |
4773 | tsk_cpus_allowed(p)); | |
4774 | goto done; | |
4775 | next: | |
4776 | sg = sg->next; | |
4777 | } while (sg != sd->groups); | |
4778 | } | |
4779 | done: | |
a50bde51 PZ |
4780 | return target; |
4781 | } | |
8bb5b00c VG |
4782 | /* |
4783 | * get_cpu_usage returns the amount of capacity of a CPU that is used by CFS | |
4784 | * tasks. The unit of the return value must be the one of capacity so we can | |
4785 | * compare the usage with the capacity of the CPU that is available for CFS | |
4786 | * task (ie cpu_capacity). | |
4787 | * cfs.utilization_load_avg is the sum of running time of runnable tasks on a | |
4788 | * CPU. It represents the amount of utilization of a CPU in the range | |
4789 | * [0..SCHED_LOAD_SCALE]. The usage of a CPU can't be higher than the full | |
4790 | * capacity of the CPU because it's about the running time on this CPU. | |
4791 | * Nevertheless, cfs.utilization_load_avg can be higher than SCHED_LOAD_SCALE | |
4792 | * because of unfortunate rounding in avg_period and running_load_avg or just | |
4793 | * after migrating tasks until the average stabilizes with the new running | |
4794 | * time. So we need to check that the usage stays into the range | |
4795 | * [0..cpu_capacity_orig] and cap if necessary. | |
4796 | * Without capping the usage, a group could be seen as overloaded (CPU0 usage | |
4797 | * at 121% + CPU1 usage at 80%) whereas CPU1 has 20% of available capacity | |
4798 | */ | |
4799 | static int get_cpu_usage(int cpu) | |
4800 | { | |
4801 | unsigned long usage = cpu_rq(cpu)->cfs.utilization_load_avg; | |
4802 | unsigned long capacity = capacity_orig_of(cpu); | |
4803 | ||
4804 | if (usage >= SCHED_LOAD_SCALE) | |
4805 | return capacity; | |
4806 | ||
4807 | return (usage * capacity) >> SCHED_LOAD_SHIFT; | |
4808 | } | |
a50bde51 | 4809 | |
aaee1203 | 4810 | /* |
de91b9cb MR |
4811 | * select_task_rq_fair: Select target runqueue for the waking task in domains |
4812 | * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE, | |
4813 | * SD_BALANCE_FORK, or SD_BALANCE_EXEC. | |
aaee1203 | 4814 | * |
de91b9cb MR |
4815 | * Balances load by selecting the idlest cpu in the idlest group, or under |
4816 | * certain conditions an idle sibling cpu if the domain has SD_WAKE_AFFINE set. | |
aaee1203 | 4817 | * |
de91b9cb | 4818 | * Returns the target cpu number. |
aaee1203 PZ |
4819 | * |
4820 | * preempt must be disabled. | |
4821 | */ | |
0017d735 | 4822 | static int |
ac66f547 | 4823 | select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags) |
aaee1203 | 4824 | { |
29cd8bae | 4825 | struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL; |
c88d5910 | 4826 | int cpu = smp_processor_id(); |
c88d5910 | 4827 | int new_cpu = cpu; |
99bd5e2f | 4828 | int want_affine = 0; |
5158f4e4 | 4829 | int sync = wake_flags & WF_SYNC; |
c88d5910 | 4830 | |
a8edd075 KT |
4831 | if (sd_flag & SD_BALANCE_WAKE) |
4832 | want_affine = cpumask_test_cpu(cpu, tsk_cpus_allowed(p)); | |
aaee1203 | 4833 | |
dce840a0 | 4834 | rcu_read_lock(); |
aaee1203 | 4835 | for_each_domain(cpu, tmp) { |
e4f42888 PZ |
4836 | if (!(tmp->flags & SD_LOAD_BALANCE)) |
4837 | continue; | |
4838 | ||
fe3bcfe1 | 4839 | /* |
99bd5e2f SS |
4840 | * If both cpu and prev_cpu are part of this domain, |
4841 | * cpu is a valid SD_WAKE_AFFINE target. | |
fe3bcfe1 | 4842 | */ |
99bd5e2f SS |
4843 | if (want_affine && (tmp->flags & SD_WAKE_AFFINE) && |
4844 | cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) { | |
4845 | affine_sd = tmp; | |
29cd8bae | 4846 | break; |
f03542a7 | 4847 | } |
29cd8bae | 4848 | |
f03542a7 | 4849 | if (tmp->flags & sd_flag) |
29cd8bae PZ |
4850 | sd = tmp; |
4851 | } | |
4852 | ||
8bf21433 RR |
4853 | if (affine_sd && cpu != prev_cpu && wake_affine(affine_sd, p, sync)) |
4854 | prev_cpu = cpu; | |
dce840a0 | 4855 | |
8bf21433 | 4856 | if (sd_flag & SD_BALANCE_WAKE) { |
dce840a0 PZ |
4857 | new_cpu = select_idle_sibling(p, prev_cpu); |
4858 | goto unlock; | |
8b911acd | 4859 | } |
e7693a36 | 4860 | |
aaee1203 PZ |
4861 | while (sd) { |
4862 | struct sched_group *group; | |
c88d5910 | 4863 | int weight; |
098fb9db | 4864 | |
0763a660 | 4865 | if (!(sd->flags & sd_flag)) { |
aaee1203 PZ |
4866 | sd = sd->child; |
4867 | continue; | |
4868 | } | |
098fb9db | 4869 | |
c44f2a02 | 4870 | group = find_idlest_group(sd, p, cpu, sd_flag); |
aaee1203 PZ |
4871 | if (!group) { |
4872 | sd = sd->child; | |
4873 | continue; | |
4874 | } | |
4ae7d5ce | 4875 | |
d7c33c49 | 4876 | new_cpu = find_idlest_cpu(group, p, cpu); |
aaee1203 PZ |
4877 | if (new_cpu == -1 || new_cpu == cpu) { |
4878 | /* Now try balancing at a lower domain level of cpu */ | |
4879 | sd = sd->child; | |
4880 | continue; | |
e7693a36 | 4881 | } |
aaee1203 PZ |
4882 | |
4883 | /* Now try balancing at a lower domain level of new_cpu */ | |
4884 | cpu = new_cpu; | |
669c55e9 | 4885 | weight = sd->span_weight; |
aaee1203 PZ |
4886 | sd = NULL; |
4887 | for_each_domain(cpu, tmp) { | |
669c55e9 | 4888 | if (weight <= tmp->span_weight) |
aaee1203 | 4889 | break; |
0763a660 | 4890 | if (tmp->flags & sd_flag) |
aaee1203 PZ |
4891 | sd = tmp; |
4892 | } | |
4893 | /* while loop will break here if sd == NULL */ | |
e7693a36 | 4894 | } |
dce840a0 PZ |
4895 | unlock: |
4896 | rcu_read_unlock(); | |
e7693a36 | 4897 | |
c88d5910 | 4898 | return new_cpu; |
e7693a36 | 4899 | } |
0a74bef8 PT |
4900 | |
4901 | /* | |
4902 | * Called immediately before a task is migrated to a new cpu; task_cpu(p) and | |
4903 | * cfs_rq_of(p) references at time of call are still valid and identify the | |
4904 | * previous cpu. However, the caller only guarantees p->pi_lock is held; no | |
4905 | * other assumptions, including the state of rq->lock, should be made. | |
4906 | */ | |
4907 | static void | |
4908 | migrate_task_rq_fair(struct task_struct *p, int next_cpu) | |
4909 | { | |
aff3e498 PT |
4910 | struct sched_entity *se = &p->se; |
4911 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
4912 | ||
4913 | /* | |
4914 | * Load tracking: accumulate removed load so that it can be processed | |
4915 | * when we next update owning cfs_rq under rq->lock. Tasks contribute | |
4916 | * to blocked load iff they have a positive decay-count. It can never | |
4917 | * be negative here since on-rq tasks have decay-count == 0. | |
4918 | */ | |
4919 | if (se->avg.decay_count) { | |
4920 | se->avg.decay_count = -__synchronize_entity_decay(se); | |
2509940f AS |
4921 | atomic_long_add(se->avg.load_avg_contrib, |
4922 | &cfs_rq->removed_load); | |
aff3e498 | 4923 | } |
3944a927 BS |
4924 | |
4925 | /* We have migrated, no longer consider this task hot */ | |
4926 | se->exec_start = 0; | |
0a74bef8 | 4927 | } |
e7693a36 GH |
4928 | #endif /* CONFIG_SMP */ |
4929 | ||
e52fb7c0 PZ |
4930 | static unsigned long |
4931 | wakeup_gran(struct sched_entity *curr, struct sched_entity *se) | |
0bbd3336 PZ |
4932 | { |
4933 | unsigned long gran = sysctl_sched_wakeup_granularity; | |
4934 | ||
4935 | /* | |
e52fb7c0 PZ |
4936 | * Since its curr running now, convert the gran from real-time |
4937 | * to virtual-time in his units. | |
13814d42 MG |
4938 | * |
4939 | * By using 'se' instead of 'curr' we penalize light tasks, so | |
4940 | * they get preempted easier. That is, if 'se' < 'curr' then | |
4941 | * the resulting gran will be larger, therefore penalizing the | |
4942 | * lighter, if otoh 'se' > 'curr' then the resulting gran will | |
4943 | * be smaller, again penalizing the lighter task. | |
4944 | * | |
4945 | * This is especially important for buddies when the leftmost | |
4946 | * task is higher priority than the buddy. | |
0bbd3336 | 4947 | */ |
f4ad9bd2 | 4948 | return calc_delta_fair(gran, se); |
0bbd3336 PZ |
4949 | } |
4950 | ||
464b7527 PZ |
4951 | /* |
4952 | * Should 'se' preempt 'curr'. | |
4953 | * | |
4954 | * |s1 | |
4955 | * |s2 | |
4956 | * |s3 | |
4957 | * g | |
4958 | * |<--->|c | |
4959 | * | |
4960 | * w(c, s1) = -1 | |
4961 | * w(c, s2) = 0 | |
4962 | * w(c, s3) = 1 | |
4963 | * | |
4964 | */ | |
4965 | static int | |
4966 | wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se) | |
4967 | { | |
4968 | s64 gran, vdiff = curr->vruntime - se->vruntime; | |
4969 | ||
4970 | if (vdiff <= 0) | |
4971 | return -1; | |
4972 | ||
e52fb7c0 | 4973 | gran = wakeup_gran(curr, se); |
464b7527 PZ |
4974 | if (vdiff > gran) |
4975 | return 1; | |
4976 | ||
4977 | return 0; | |
4978 | } | |
4979 | ||
02479099 PZ |
4980 | static void set_last_buddy(struct sched_entity *se) |
4981 | { | |
69c80f3e VP |
4982 | if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
4983 | return; | |
4984 | ||
4985 | for_each_sched_entity(se) | |
4986 | cfs_rq_of(se)->last = se; | |
02479099 PZ |
4987 | } |
4988 | ||
4989 | static void set_next_buddy(struct sched_entity *se) | |
4990 | { | |
69c80f3e VP |
4991 | if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
4992 | return; | |
4993 | ||
4994 | for_each_sched_entity(se) | |
4995 | cfs_rq_of(se)->next = se; | |
02479099 PZ |
4996 | } |
4997 | ||
ac53db59 RR |
4998 | static void set_skip_buddy(struct sched_entity *se) |
4999 | { | |
69c80f3e VP |
5000 | for_each_sched_entity(se) |
5001 | cfs_rq_of(se)->skip = se; | |
ac53db59 RR |
5002 | } |
5003 | ||
bf0f6f24 IM |
5004 | /* |
5005 | * Preempt the current task with a newly woken task if needed: | |
5006 | */ | |
5a9b86f6 | 5007 | static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) |
bf0f6f24 IM |
5008 | { |
5009 | struct task_struct *curr = rq->curr; | |
8651a86c | 5010 | struct sched_entity *se = &curr->se, *pse = &p->se; |
03e89e45 | 5011 | struct cfs_rq *cfs_rq = task_cfs_rq(curr); |
f685ceac | 5012 | int scale = cfs_rq->nr_running >= sched_nr_latency; |
2f36825b | 5013 | int next_buddy_marked = 0; |
bf0f6f24 | 5014 | |
4ae7d5ce IM |
5015 | if (unlikely(se == pse)) |
5016 | return; | |
5017 | ||
5238cdd3 | 5018 | /* |
163122b7 | 5019 | * This is possible from callers such as attach_tasks(), in which we |
5238cdd3 PT |
5020 | * unconditionally check_prempt_curr() after an enqueue (which may have |
5021 | * lead to a throttle). This both saves work and prevents false | |
5022 | * next-buddy nomination below. | |
5023 | */ | |
5024 | if (unlikely(throttled_hierarchy(cfs_rq_of(pse)))) | |
5025 | return; | |
5026 | ||
2f36825b | 5027 | if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) { |
3cb63d52 | 5028 | set_next_buddy(pse); |
2f36825b VP |
5029 | next_buddy_marked = 1; |
5030 | } | |
57fdc26d | 5031 | |
aec0a514 BR |
5032 | /* |
5033 | * We can come here with TIF_NEED_RESCHED already set from new task | |
5034 | * wake up path. | |
5238cdd3 PT |
5035 | * |
5036 | * Note: this also catches the edge-case of curr being in a throttled | |
5037 | * group (e.g. via set_curr_task), since update_curr() (in the | |
5038 | * enqueue of curr) will have resulted in resched being set. This | |
5039 | * prevents us from potentially nominating it as a false LAST_BUDDY | |
5040 | * below. | |
aec0a514 BR |
5041 | */ |
5042 | if (test_tsk_need_resched(curr)) | |
5043 | return; | |
5044 | ||
a2f5c9ab DH |
5045 | /* Idle tasks are by definition preempted by non-idle tasks. */ |
5046 | if (unlikely(curr->policy == SCHED_IDLE) && | |
5047 | likely(p->policy != SCHED_IDLE)) | |
5048 | goto preempt; | |
5049 | ||
91c234b4 | 5050 | /* |
a2f5c9ab DH |
5051 | * Batch and idle tasks do not preempt non-idle tasks (their preemption |
5052 | * is driven by the tick): | |
91c234b4 | 5053 | */ |
8ed92e51 | 5054 | if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION)) |
91c234b4 | 5055 | return; |
bf0f6f24 | 5056 | |
464b7527 | 5057 | find_matching_se(&se, &pse); |
9bbd7374 | 5058 | update_curr(cfs_rq_of(se)); |
002f128b | 5059 | BUG_ON(!pse); |
2f36825b VP |
5060 | if (wakeup_preempt_entity(se, pse) == 1) { |
5061 | /* | |
5062 | * Bias pick_next to pick the sched entity that is | |
5063 | * triggering this preemption. | |
5064 | */ | |
5065 | if (!next_buddy_marked) | |
5066 | set_next_buddy(pse); | |
3a7e73a2 | 5067 | goto preempt; |
2f36825b | 5068 | } |
464b7527 | 5069 | |
3a7e73a2 | 5070 | return; |
a65ac745 | 5071 | |
3a7e73a2 | 5072 | preempt: |
8875125e | 5073 | resched_curr(rq); |
3a7e73a2 PZ |
5074 | /* |
5075 | * Only set the backward buddy when the current task is still | |
5076 | * on the rq. This can happen when a wakeup gets interleaved | |
5077 | * with schedule on the ->pre_schedule() or idle_balance() | |
5078 | * point, either of which can * drop the rq lock. | |
5079 | * | |
5080 | * Also, during early boot the idle thread is in the fair class, | |
5081 | * for obvious reasons its a bad idea to schedule back to it. | |
5082 | */ | |
5083 | if (unlikely(!se->on_rq || curr == rq->idle)) | |
5084 | return; | |
5085 | ||
5086 | if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se)) | |
5087 | set_last_buddy(se); | |
bf0f6f24 IM |
5088 | } |
5089 | ||
606dba2e PZ |
5090 | static struct task_struct * |
5091 | pick_next_task_fair(struct rq *rq, struct task_struct *prev) | |
bf0f6f24 IM |
5092 | { |
5093 | struct cfs_rq *cfs_rq = &rq->cfs; | |
5094 | struct sched_entity *se; | |
678d5718 | 5095 | struct task_struct *p; |
37e117c0 | 5096 | int new_tasks; |
678d5718 | 5097 | |
6e83125c | 5098 | again: |
678d5718 PZ |
5099 | #ifdef CONFIG_FAIR_GROUP_SCHED |
5100 | if (!cfs_rq->nr_running) | |
38033c37 | 5101 | goto idle; |
678d5718 | 5102 | |
3f1d2a31 | 5103 | if (prev->sched_class != &fair_sched_class) |
678d5718 PZ |
5104 | goto simple; |
5105 | ||
5106 | /* | |
5107 | * Because of the set_next_buddy() in dequeue_task_fair() it is rather | |
5108 | * likely that a next task is from the same cgroup as the current. | |
5109 | * | |
5110 | * Therefore attempt to avoid putting and setting the entire cgroup | |
5111 | * hierarchy, only change the part that actually changes. | |
5112 | */ | |
5113 | ||
5114 | do { | |
5115 | struct sched_entity *curr = cfs_rq->curr; | |
5116 | ||
5117 | /* | |
5118 | * Since we got here without doing put_prev_entity() we also | |
5119 | * have to consider cfs_rq->curr. If it is still a runnable | |
5120 | * entity, update_curr() will update its vruntime, otherwise | |
5121 | * forget we've ever seen it. | |
5122 | */ | |
5123 | if (curr && curr->on_rq) | |
5124 | update_curr(cfs_rq); | |
5125 | else | |
5126 | curr = NULL; | |
5127 | ||
5128 | /* | |
5129 | * This call to check_cfs_rq_runtime() will do the throttle and | |
5130 | * dequeue its entity in the parent(s). Therefore the 'simple' | |
5131 | * nr_running test will indeed be correct. | |
5132 | */ | |
5133 | if (unlikely(check_cfs_rq_runtime(cfs_rq))) | |
5134 | goto simple; | |
5135 | ||
5136 | se = pick_next_entity(cfs_rq, curr); | |
5137 | cfs_rq = group_cfs_rq(se); | |
5138 | } while (cfs_rq); | |
5139 | ||
5140 | p = task_of(se); | |
5141 | ||
5142 | /* | |
5143 | * Since we haven't yet done put_prev_entity and if the selected task | |
5144 | * is a different task than we started out with, try and touch the | |
5145 | * least amount of cfs_rqs. | |
5146 | */ | |
5147 | if (prev != p) { | |
5148 | struct sched_entity *pse = &prev->se; | |
5149 | ||
5150 | while (!(cfs_rq = is_same_group(se, pse))) { | |
5151 | int se_depth = se->depth; | |
5152 | int pse_depth = pse->depth; | |
5153 | ||
5154 | if (se_depth <= pse_depth) { | |
5155 | put_prev_entity(cfs_rq_of(pse), pse); | |
5156 | pse = parent_entity(pse); | |
5157 | } | |
5158 | if (se_depth >= pse_depth) { | |
5159 | set_next_entity(cfs_rq_of(se), se); | |
5160 | se = parent_entity(se); | |
5161 | } | |
5162 | } | |
5163 | ||
5164 | put_prev_entity(cfs_rq, pse); | |
5165 | set_next_entity(cfs_rq, se); | |
5166 | } | |
5167 | ||
5168 | if (hrtick_enabled(rq)) | |
5169 | hrtick_start_fair(rq, p); | |
5170 | ||
5171 | return p; | |
5172 | simple: | |
5173 | cfs_rq = &rq->cfs; | |
5174 | #endif | |
bf0f6f24 | 5175 | |
36ace27e | 5176 | if (!cfs_rq->nr_running) |
38033c37 | 5177 | goto idle; |
bf0f6f24 | 5178 | |
3f1d2a31 | 5179 | put_prev_task(rq, prev); |
606dba2e | 5180 | |
bf0f6f24 | 5181 | do { |
678d5718 | 5182 | se = pick_next_entity(cfs_rq, NULL); |
f4b6755f | 5183 | set_next_entity(cfs_rq, se); |
bf0f6f24 IM |
5184 | cfs_rq = group_cfs_rq(se); |
5185 | } while (cfs_rq); | |
5186 | ||
8f4d37ec | 5187 | p = task_of(se); |
678d5718 | 5188 | |
b39e66ea MG |
5189 | if (hrtick_enabled(rq)) |
5190 | hrtick_start_fair(rq, p); | |
8f4d37ec PZ |
5191 | |
5192 | return p; | |
38033c37 PZ |
5193 | |
5194 | idle: | |
e4aa358b | 5195 | new_tasks = idle_balance(rq); |
37e117c0 PZ |
5196 | /* |
5197 | * Because idle_balance() releases (and re-acquires) rq->lock, it is | |
5198 | * possible for any higher priority task to appear. In that case we | |
5199 | * must re-start the pick_next_entity() loop. | |
5200 | */ | |
e4aa358b | 5201 | if (new_tasks < 0) |
37e117c0 PZ |
5202 | return RETRY_TASK; |
5203 | ||
e4aa358b | 5204 | if (new_tasks > 0) |
38033c37 | 5205 | goto again; |
38033c37 PZ |
5206 | |
5207 | return NULL; | |
bf0f6f24 IM |
5208 | } |
5209 | ||
5210 | /* | |
5211 | * Account for a descheduled task: | |
5212 | */ | |
31ee529c | 5213 | static void put_prev_task_fair(struct rq *rq, struct task_struct *prev) |
bf0f6f24 IM |
5214 | { |
5215 | struct sched_entity *se = &prev->se; | |
5216 | struct cfs_rq *cfs_rq; | |
5217 | ||
5218 | for_each_sched_entity(se) { | |
5219 | cfs_rq = cfs_rq_of(se); | |
ab6cde26 | 5220 | put_prev_entity(cfs_rq, se); |
bf0f6f24 IM |
5221 | } |
5222 | } | |
5223 | ||
ac53db59 RR |
5224 | /* |
5225 | * sched_yield() is very simple | |
5226 | * | |
5227 | * The magic of dealing with the ->skip buddy is in pick_next_entity. | |
5228 | */ | |
5229 | static void yield_task_fair(struct rq *rq) | |
5230 | { | |
5231 | struct task_struct *curr = rq->curr; | |
5232 | struct cfs_rq *cfs_rq = task_cfs_rq(curr); | |
5233 | struct sched_entity *se = &curr->se; | |
5234 | ||
5235 | /* | |
5236 | * Are we the only task in the tree? | |
5237 | */ | |
5238 | if (unlikely(rq->nr_running == 1)) | |
5239 | return; | |
5240 | ||
5241 | clear_buddies(cfs_rq, se); | |
5242 | ||
5243 | if (curr->policy != SCHED_BATCH) { | |
5244 | update_rq_clock(rq); | |
5245 | /* | |
5246 | * Update run-time statistics of the 'current'. | |
5247 | */ | |
5248 | update_curr(cfs_rq); | |
916671c0 MG |
5249 | /* |
5250 | * Tell update_rq_clock() that we've just updated, | |
5251 | * so we don't do microscopic update in schedule() | |
5252 | * and double the fastpath cost. | |
5253 | */ | |
9edfbfed | 5254 | rq_clock_skip_update(rq, true); |
ac53db59 RR |
5255 | } |
5256 | ||
5257 | set_skip_buddy(se); | |
5258 | } | |
5259 | ||
d95f4122 MG |
5260 | static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt) |
5261 | { | |
5262 | struct sched_entity *se = &p->se; | |
5263 | ||
5238cdd3 PT |
5264 | /* throttled hierarchies are not runnable */ |
5265 | if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se))) | |
d95f4122 MG |
5266 | return false; |
5267 | ||
5268 | /* Tell the scheduler that we'd really like pse to run next. */ | |
5269 | set_next_buddy(se); | |
5270 | ||
d95f4122 MG |
5271 | yield_task_fair(rq); |
5272 | ||
5273 | return true; | |
5274 | } | |
5275 | ||
681f3e68 | 5276 | #ifdef CONFIG_SMP |
bf0f6f24 | 5277 | /************************************************** |
e9c84cb8 PZ |
5278 | * Fair scheduling class load-balancing methods. |
5279 | * | |
5280 | * BASICS | |
5281 | * | |
5282 | * The purpose of load-balancing is to achieve the same basic fairness the | |
5283 | * per-cpu scheduler provides, namely provide a proportional amount of compute | |
5284 | * time to each task. This is expressed in the following equation: | |
5285 | * | |
5286 | * W_i,n/P_i == W_j,n/P_j for all i,j (1) | |
5287 | * | |
5288 | * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight | |
5289 | * W_i,0 is defined as: | |
5290 | * | |
5291 | * W_i,0 = \Sum_j w_i,j (2) | |
5292 | * | |
5293 | * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight | |
5294 | * is derived from the nice value as per prio_to_weight[]. | |
5295 | * | |
5296 | * The weight average is an exponential decay average of the instantaneous | |
5297 | * weight: | |
5298 | * | |
5299 | * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3) | |
5300 | * | |
ced549fa | 5301 | * C_i is the compute capacity of cpu i, typically it is the |
e9c84cb8 PZ |
5302 | * fraction of 'recent' time available for SCHED_OTHER task execution. But it |
5303 | * can also include other factors [XXX]. | |
5304 | * | |
5305 | * To achieve this balance we define a measure of imbalance which follows | |
5306 | * directly from (1): | |
5307 | * | |
ced549fa | 5308 | * imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j } (4) |
e9c84cb8 PZ |
5309 | * |
5310 | * We them move tasks around to minimize the imbalance. In the continuous | |
5311 | * function space it is obvious this converges, in the discrete case we get | |
5312 | * a few fun cases generally called infeasible weight scenarios. | |
5313 | * | |
5314 | * [XXX expand on: | |
5315 | * - infeasible weights; | |
5316 | * - local vs global optima in the discrete case. ] | |
5317 | * | |
5318 | * | |
5319 | * SCHED DOMAINS | |
5320 | * | |
5321 | * In order to solve the imbalance equation (4), and avoid the obvious O(n^2) | |
5322 | * for all i,j solution, we create a tree of cpus that follows the hardware | |
5323 | * topology where each level pairs two lower groups (or better). This results | |
5324 | * in O(log n) layers. Furthermore we reduce the number of cpus going up the | |
5325 | * tree to only the first of the previous level and we decrease the frequency | |
5326 | * of load-balance at each level inv. proportional to the number of cpus in | |
5327 | * the groups. | |
5328 | * | |
5329 | * This yields: | |
5330 | * | |
5331 | * log_2 n 1 n | |
5332 | * \Sum { --- * --- * 2^i } = O(n) (5) | |
5333 | * i = 0 2^i 2^i | |
5334 | * `- size of each group | |
5335 | * | | `- number of cpus doing load-balance | |
5336 | * | `- freq | |
5337 | * `- sum over all levels | |
5338 | * | |
5339 | * Coupled with a limit on how many tasks we can migrate every balance pass, | |
5340 | * this makes (5) the runtime complexity of the balancer. | |
5341 | * | |
5342 | * An important property here is that each CPU is still (indirectly) connected | |
5343 | * to every other cpu in at most O(log n) steps: | |
5344 | * | |
5345 | * The adjacency matrix of the resulting graph is given by: | |
5346 | * | |
5347 | * log_2 n | |
5348 | * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6) | |
5349 | * k = 0 | |
5350 | * | |
5351 | * And you'll find that: | |
5352 | * | |
5353 | * A^(log_2 n)_i,j != 0 for all i,j (7) | |
5354 | * | |
5355 | * Showing there's indeed a path between every cpu in at most O(log n) steps. | |
5356 | * The task movement gives a factor of O(m), giving a convergence complexity | |
5357 | * of: | |
5358 | * | |
5359 | * O(nm log n), n := nr_cpus, m := nr_tasks (8) | |
5360 | * | |
5361 | * | |
5362 | * WORK CONSERVING | |
5363 | * | |
5364 | * In order to avoid CPUs going idle while there's still work to do, new idle | |
5365 | * balancing is more aggressive and has the newly idle cpu iterate up the domain | |
5366 | * tree itself instead of relying on other CPUs to bring it work. | |
5367 | * | |
5368 | * This adds some complexity to both (5) and (8) but it reduces the total idle | |
5369 | * time. | |
5370 | * | |
5371 | * [XXX more?] | |
5372 | * | |
5373 | * | |
5374 | * CGROUPS | |
5375 | * | |
5376 | * Cgroups make a horror show out of (2), instead of a simple sum we get: | |
5377 | * | |
5378 | * s_k,i | |
5379 | * W_i,0 = \Sum_j \Prod_k w_k * ----- (9) | |
5380 | * S_k | |
5381 | * | |
5382 | * Where | |
5383 | * | |
5384 | * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10) | |
5385 | * | |
5386 | * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i. | |
5387 | * | |
5388 | * The big problem is S_k, its a global sum needed to compute a local (W_i) | |
5389 | * property. | |
5390 | * | |
5391 | * [XXX write more on how we solve this.. _after_ merging pjt's patches that | |
5392 | * rewrite all of this once again.] | |
5393 | */ | |
bf0f6f24 | 5394 | |
ed387b78 HS |
5395 | static unsigned long __read_mostly max_load_balance_interval = HZ/10; |
5396 | ||
0ec8aa00 PZ |
5397 | enum fbq_type { regular, remote, all }; |
5398 | ||
ddcdf6e7 | 5399 | #define LBF_ALL_PINNED 0x01 |
367456c7 | 5400 | #define LBF_NEED_BREAK 0x02 |
6263322c PZ |
5401 | #define LBF_DST_PINNED 0x04 |
5402 | #define LBF_SOME_PINNED 0x08 | |
ddcdf6e7 PZ |
5403 | |
5404 | struct lb_env { | |
5405 | struct sched_domain *sd; | |
5406 | ||
ddcdf6e7 | 5407 | struct rq *src_rq; |
85c1e7da | 5408 | int src_cpu; |
ddcdf6e7 PZ |
5409 | |
5410 | int dst_cpu; | |
5411 | struct rq *dst_rq; | |
5412 | ||
88b8dac0 SV |
5413 | struct cpumask *dst_grpmask; |
5414 | int new_dst_cpu; | |
ddcdf6e7 | 5415 | enum cpu_idle_type idle; |
bd939f45 | 5416 | long imbalance; |
b9403130 MW |
5417 | /* The set of CPUs under consideration for load-balancing */ |
5418 | struct cpumask *cpus; | |
5419 | ||
ddcdf6e7 | 5420 | unsigned int flags; |
367456c7 PZ |
5421 | |
5422 | unsigned int loop; | |
5423 | unsigned int loop_break; | |
5424 | unsigned int loop_max; | |
0ec8aa00 PZ |
5425 | |
5426 | enum fbq_type fbq_type; | |
163122b7 | 5427 | struct list_head tasks; |
ddcdf6e7 PZ |
5428 | }; |
5429 | ||
029632fb PZ |
5430 | /* |
5431 | * Is this task likely cache-hot: | |
5432 | */ | |
5d5e2b1b | 5433 | static int task_hot(struct task_struct *p, struct lb_env *env) |
029632fb PZ |
5434 | { |
5435 | s64 delta; | |
5436 | ||
e5673f28 KT |
5437 | lockdep_assert_held(&env->src_rq->lock); |
5438 | ||
029632fb PZ |
5439 | if (p->sched_class != &fair_sched_class) |
5440 | return 0; | |
5441 | ||
5442 | if (unlikely(p->policy == SCHED_IDLE)) | |
5443 | return 0; | |
5444 | ||
5445 | /* | |
5446 | * Buddy candidates are cache hot: | |
5447 | */ | |
5d5e2b1b | 5448 | if (sched_feat(CACHE_HOT_BUDDY) && env->dst_rq->nr_running && |
029632fb PZ |
5449 | (&p->se == cfs_rq_of(&p->se)->next || |
5450 | &p->se == cfs_rq_of(&p->se)->last)) | |
5451 | return 1; | |
5452 | ||
5453 | if (sysctl_sched_migration_cost == -1) | |
5454 | return 1; | |
5455 | if (sysctl_sched_migration_cost == 0) | |
5456 | return 0; | |
5457 | ||
5d5e2b1b | 5458 | delta = rq_clock_task(env->src_rq) - p->se.exec_start; |
029632fb PZ |
5459 | |
5460 | return delta < (s64)sysctl_sched_migration_cost; | |
5461 | } | |
5462 | ||
3a7053b3 MG |
5463 | #ifdef CONFIG_NUMA_BALANCING |
5464 | /* Returns true if the destination node has incurred more faults */ | |
5465 | static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env) | |
5466 | { | |
b1ad065e | 5467 | struct numa_group *numa_group = rcu_dereference(p->numa_group); |
3a7053b3 MG |
5468 | int src_nid, dst_nid; |
5469 | ||
44dba3d5 | 5470 | if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults || |
3a7053b3 MG |
5471 | !(env->sd->flags & SD_NUMA)) { |
5472 | return false; | |
5473 | } | |
5474 | ||
5475 | src_nid = cpu_to_node(env->src_cpu); | |
5476 | dst_nid = cpu_to_node(env->dst_cpu); | |
5477 | ||
83e1d2cd | 5478 | if (src_nid == dst_nid) |
3a7053b3 MG |
5479 | return false; |
5480 | ||
b1ad065e RR |
5481 | if (numa_group) { |
5482 | /* Task is already in the group's interleave set. */ | |
5483 | if (node_isset(src_nid, numa_group->active_nodes)) | |
5484 | return false; | |
83e1d2cd | 5485 | |
b1ad065e RR |
5486 | /* Task is moving into the group's interleave set. */ |
5487 | if (node_isset(dst_nid, numa_group->active_nodes)) | |
5488 | return true; | |
83e1d2cd | 5489 | |
b1ad065e RR |
5490 | return group_faults(p, dst_nid) > group_faults(p, src_nid); |
5491 | } | |
5492 | ||
5493 | /* Encourage migration to the preferred node. */ | |
5494 | if (dst_nid == p->numa_preferred_nid) | |
3a7053b3 MG |
5495 | return true; |
5496 | ||
b1ad065e | 5497 | return task_faults(p, dst_nid) > task_faults(p, src_nid); |
3a7053b3 | 5498 | } |
7a0f3083 MG |
5499 | |
5500 | ||
5501 | static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env) | |
5502 | { | |
b1ad065e | 5503 | struct numa_group *numa_group = rcu_dereference(p->numa_group); |
7a0f3083 MG |
5504 | int src_nid, dst_nid; |
5505 | ||
5506 | if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER)) | |
5507 | return false; | |
5508 | ||
44dba3d5 | 5509 | if (!p->numa_faults || !(env->sd->flags & SD_NUMA)) |
7a0f3083 MG |
5510 | return false; |
5511 | ||
5512 | src_nid = cpu_to_node(env->src_cpu); | |
5513 | dst_nid = cpu_to_node(env->dst_cpu); | |
5514 | ||
83e1d2cd | 5515 | if (src_nid == dst_nid) |
7a0f3083 MG |
5516 | return false; |
5517 | ||
b1ad065e RR |
5518 | if (numa_group) { |
5519 | /* Task is moving within/into the group's interleave set. */ | |
5520 | if (node_isset(dst_nid, numa_group->active_nodes)) | |
5521 | return false; | |
5522 | ||
5523 | /* Task is moving out of the group's interleave set. */ | |
5524 | if (node_isset(src_nid, numa_group->active_nodes)) | |
5525 | return true; | |
5526 | ||
5527 | return group_faults(p, dst_nid) < group_faults(p, src_nid); | |
5528 | } | |
5529 | ||
83e1d2cd MG |
5530 | /* Migrating away from the preferred node is always bad. */ |
5531 | if (src_nid == p->numa_preferred_nid) | |
5532 | return true; | |
5533 | ||
b1ad065e | 5534 | return task_faults(p, dst_nid) < task_faults(p, src_nid); |
7a0f3083 MG |
5535 | } |
5536 | ||
3a7053b3 MG |
5537 | #else |
5538 | static inline bool migrate_improves_locality(struct task_struct *p, | |
5539 | struct lb_env *env) | |
5540 | { | |
5541 | return false; | |
5542 | } | |
7a0f3083 MG |
5543 | |
5544 | static inline bool migrate_degrades_locality(struct task_struct *p, | |
5545 | struct lb_env *env) | |
5546 | { | |
5547 | return false; | |
5548 | } | |
3a7053b3 MG |
5549 | #endif |
5550 | ||
1e3c88bd PZ |
5551 | /* |
5552 | * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? | |
5553 | */ | |
5554 | static | |
8e45cb54 | 5555 | int can_migrate_task(struct task_struct *p, struct lb_env *env) |
1e3c88bd PZ |
5556 | { |
5557 | int tsk_cache_hot = 0; | |
e5673f28 KT |
5558 | |
5559 | lockdep_assert_held(&env->src_rq->lock); | |
5560 | ||
1e3c88bd PZ |
5561 | /* |
5562 | * We do not migrate tasks that are: | |
d3198084 | 5563 | * 1) throttled_lb_pair, or |
1e3c88bd | 5564 | * 2) cannot be migrated to this CPU due to cpus_allowed, or |
d3198084 JK |
5565 | * 3) running (obviously), or |
5566 | * 4) are cache-hot on their current CPU. | |
1e3c88bd | 5567 | */ |
d3198084 JK |
5568 | if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu)) |
5569 | return 0; | |
5570 | ||
ddcdf6e7 | 5571 | if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) { |
e02e60c1 | 5572 | int cpu; |
88b8dac0 | 5573 | |
41acab88 | 5574 | schedstat_inc(p, se.statistics.nr_failed_migrations_affine); |
88b8dac0 | 5575 | |
6263322c PZ |
5576 | env->flags |= LBF_SOME_PINNED; |
5577 | ||
88b8dac0 SV |
5578 | /* |
5579 | * Remember if this task can be migrated to any other cpu in | |
5580 | * our sched_group. We may want to revisit it if we couldn't | |
5581 | * meet load balance goals by pulling other tasks on src_cpu. | |
5582 | * | |
5583 | * Also avoid computing new_dst_cpu if we have already computed | |
5584 | * one in current iteration. | |
5585 | */ | |
6263322c | 5586 | if (!env->dst_grpmask || (env->flags & LBF_DST_PINNED)) |
88b8dac0 SV |
5587 | return 0; |
5588 | ||
e02e60c1 JK |
5589 | /* Prevent to re-select dst_cpu via env's cpus */ |
5590 | for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) { | |
5591 | if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) { | |
6263322c | 5592 | env->flags |= LBF_DST_PINNED; |
e02e60c1 JK |
5593 | env->new_dst_cpu = cpu; |
5594 | break; | |
5595 | } | |
88b8dac0 | 5596 | } |
e02e60c1 | 5597 | |
1e3c88bd PZ |
5598 | return 0; |
5599 | } | |
88b8dac0 SV |
5600 | |
5601 | /* Record that we found atleast one task that could run on dst_cpu */ | |
8e45cb54 | 5602 | env->flags &= ~LBF_ALL_PINNED; |
1e3c88bd | 5603 | |
ddcdf6e7 | 5604 | if (task_running(env->src_rq, p)) { |
41acab88 | 5605 | schedstat_inc(p, se.statistics.nr_failed_migrations_running); |
1e3c88bd PZ |
5606 | return 0; |
5607 | } | |
5608 | ||
5609 | /* | |
5610 | * Aggressive migration if: | |
3a7053b3 MG |
5611 | * 1) destination numa is preferred |
5612 | * 2) task is cache cold, or | |
5613 | * 3) too many balance attempts have failed. | |
1e3c88bd | 5614 | */ |
5d5e2b1b | 5615 | tsk_cache_hot = task_hot(p, env); |
7a0f3083 MG |
5616 | if (!tsk_cache_hot) |
5617 | tsk_cache_hot = migrate_degrades_locality(p, env); | |
3a7053b3 | 5618 | |
7a96c231 KT |
5619 | if (migrate_improves_locality(p, env) || !tsk_cache_hot || |
5620 | env->sd->nr_balance_failed > env->sd->cache_nice_tries) { | |
3a7053b3 MG |
5621 | if (tsk_cache_hot) { |
5622 | schedstat_inc(env->sd, lb_hot_gained[env->idle]); | |
5623 | schedstat_inc(p, se.statistics.nr_forced_migrations); | |
5624 | } | |
1e3c88bd PZ |
5625 | return 1; |
5626 | } | |
5627 | ||
4e2dcb73 ZH |
5628 | schedstat_inc(p, se.statistics.nr_failed_migrations_hot); |
5629 | return 0; | |
1e3c88bd PZ |
5630 | } |
5631 | ||
897c395f | 5632 | /* |
163122b7 KT |
5633 | * detach_task() -- detach the task for the migration specified in env |
5634 | */ | |
5635 | static void detach_task(struct task_struct *p, struct lb_env *env) | |
5636 | { | |
5637 | lockdep_assert_held(&env->src_rq->lock); | |
5638 | ||
5639 | deactivate_task(env->src_rq, p, 0); | |
5640 | p->on_rq = TASK_ON_RQ_MIGRATING; | |
5641 | set_task_cpu(p, env->dst_cpu); | |
5642 | } | |
5643 | ||
897c395f | 5644 | /* |
e5673f28 | 5645 | * detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as |
897c395f | 5646 | * part of active balancing operations within "domain". |
897c395f | 5647 | * |
e5673f28 | 5648 | * Returns a task if successful and NULL otherwise. |
897c395f | 5649 | */ |
e5673f28 | 5650 | static struct task_struct *detach_one_task(struct lb_env *env) |
897c395f PZ |
5651 | { |
5652 | struct task_struct *p, *n; | |
897c395f | 5653 | |
e5673f28 KT |
5654 | lockdep_assert_held(&env->src_rq->lock); |
5655 | ||
367456c7 | 5656 | list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) { |
367456c7 PZ |
5657 | if (!can_migrate_task(p, env)) |
5658 | continue; | |
897c395f | 5659 | |
163122b7 | 5660 | detach_task(p, env); |
e5673f28 | 5661 | |
367456c7 | 5662 | /* |
e5673f28 | 5663 | * Right now, this is only the second place where |
163122b7 | 5664 | * lb_gained[env->idle] is updated (other is detach_tasks) |
e5673f28 | 5665 | * so we can safely collect stats here rather than |
163122b7 | 5666 | * inside detach_tasks(). |
367456c7 PZ |
5667 | */ |
5668 | schedstat_inc(env->sd, lb_gained[env->idle]); | |
e5673f28 | 5669 | return p; |
897c395f | 5670 | } |
e5673f28 | 5671 | return NULL; |
897c395f PZ |
5672 | } |
5673 | ||
eb95308e PZ |
5674 | static const unsigned int sched_nr_migrate_break = 32; |
5675 | ||
5d6523eb | 5676 | /* |
163122b7 KT |
5677 | * detach_tasks() -- tries to detach up to imbalance weighted load from |
5678 | * busiest_rq, as part of a balancing operation within domain "sd". | |
5d6523eb | 5679 | * |
163122b7 | 5680 | * Returns number of detached tasks if successful and 0 otherwise. |
5d6523eb | 5681 | */ |
163122b7 | 5682 | static int detach_tasks(struct lb_env *env) |
1e3c88bd | 5683 | { |
5d6523eb PZ |
5684 | struct list_head *tasks = &env->src_rq->cfs_tasks; |
5685 | struct task_struct *p; | |
367456c7 | 5686 | unsigned long load; |
163122b7 KT |
5687 | int detached = 0; |
5688 | ||
5689 | lockdep_assert_held(&env->src_rq->lock); | |
1e3c88bd | 5690 | |
bd939f45 | 5691 | if (env->imbalance <= 0) |
5d6523eb | 5692 | return 0; |
1e3c88bd | 5693 | |
5d6523eb PZ |
5694 | while (!list_empty(tasks)) { |
5695 | p = list_first_entry(tasks, struct task_struct, se.group_node); | |
1e3c88bd | 5696 | |
367456c7 PZ |
5697 | env->loop++; |
5698 | /* We've more or less seen every task there is, call it quits */ | |
5d6523eb | 5699 | if (env->loop > env->loop_max) |
367456c7 | 5700 | break; |
5d6523eb PZ |
5701 | |
5702 | /* take a breather every nr_migrate tasks */ | |
367456c7 | 5703 | if (env->loop > env->loop_break) { |
eb95308e | 5704 | env->loop_break += sched_nr_migrate_break; |
8e45cb54 | 5705 | env->flags |= LBF_NEED_BREAK; |
ee00e66f | 5706 | break; |
a195f004 | 5707 | } |
1e3c88bd | 5708 | |
d3198084 | 5709 | if (!can_migrate_task(p, env)) |
367456c7 PZ |
5710 | goto next; |
5711 | ||
5712 | load = task_h_load(p); | |
5d6523eb | 5713 | |
eb95308e | 5714 | if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed) |
367456c7 PZ |
5715 | goto next; |
5716 | ||
bd939f45 | 5717 | if ((load / 2) > env->imbalance) |
367456c7 | 5718 | goto next; |
1e3c88bd | 5719 | |
163122b7 KT |
5720 | detach_task(p, env); |
5721 | list_add(&p->se.group_node, &env->tasks); | |
5722 | ||
5723 | detached++; | |
bd939f45 | 5724 | env->imbalance -= load; |
1e3c88bd PZ |
5725 | |
5726 | #ifdef CONFIG_PREEMPT | |
ee00e66f PZ |
5727 | /* |
5728 | * NEWIDLE balancing is a source of latency, so preemptible | |
163122b7 | 5729 | * kernels will stop after the first task is detached to minimize |
ee00e66f PZ |
5730 | * the critical section. |
5731 | */ | |
5d6523eb | 5732 | if (env->idle == CPU_NEWLY_IDLE) |
ee00e66f | 5733 | break; |
1e3c88bd PZ |
5734 | #endif |
5735 | ||
ee00e66f PZ |
5736 | /* |
5737 | * We only want to steal up to the prescribed amount of | |
5738 | * weighted load. | |
5739 | */ | |
bd939f45 | 5740 | if (env->imbalance <= 0) |
ee00e66f | 5741 | break; |
367456c7 PZ |
5742 | |
5743 | continue; | |
5744 | next: | |
5d6523eb | 5745 | list_move_tail(&p->se.group_node, tasks); |
1e3c88bd | 5746 | } |
5d6523eb | 5747 | |
1e3c88bd | 5748 | /* |
163122b7 KT |
5749 | * Right now, this is one of only two places we collect this stat |
5750 | * so we can safely collect detach_one_task() stats here rather | |
5751 | * than inside detach_one_task(). | |
1e3c88bd | 5752 | */ |
163122b7 | 5753 | schedstat_add(env->sd, lb_gained[env->idle], detached); |
1e3c88bd | 5754 | |
163122b7 KT |
5755 | return detached; |
5756 | } | |
5757 | ||
5758 | /* | |
5759 | * attach_task() -- attach the task detached by detach_task() to its new rq. | |
5760 | */ | |
5761 | static void attach_task(struct rq *rq, struct task_struct *p) | |
5762 | { | |
5763 | lockdep_assert_held(&rq->lock); | |
5764 | ||
5765 | BUG_ON(task_rq(p) != rq); | |
5766 | p->on_rq = TASK_ON_RQ_QUEUED; | |
5767 | activate_task(rq, p, 0); | |
5768 | check_preempt_curr(rq, p, 0); | |
5769 | } | |
5770 | ||
5771 | /* | |
5772 | * attach_one_task() -- attaches the task returned from detach_one_task() to | |
5773 | * its new rq. | |
5774 | */ | |
5775 | static void attach_one_task(struct rq *rq, struct task_struct *p) | |
5776 | { | |
5777 | raw_spin_lock(&rq->lock); | |
5778 | attach_task(rq, p); | |
5779 | raw_spin_unlock(&rq->lock); | |
5780 | } | |
5781 | ||
5782 | /* | |
5783 | * attach_tasks() -- attaches all tasks detached by detach_tasks() to their | |
5784 | * new rq. | |
5785 | */ | |
5786 | static void attach_tasks(struct lb_env *env) | |
5787 | { | |
5788 | struct list_head *tasks = &env->tasks; | |
5789 | struct task_struct *p; | |
5790 | ||
5791 | raw_spin_lock(&env->dst_rq->lock); | |
5792 | ||
5793 | while (!list_empty(tasks)) { | |
5794 | p = list_first_entry(tasks, struct task_struct, se.group_node); | |
5795 | list_del_init(&p->se.group_node); | |
1e3c88bd | 5796 | |
163122b7 KT |
5797 | attach_task(env->dst_rq, p); |
5798 | } | |
5799 | ||
5800 | raw_spin_unlock(&env->dst_rq->lock); | |
1e3c88bd PZ |
5801 | } |
5802 | ||
230059de | 5803 | #ifdef CONFIG_FAIR_GROUP_SCHED |
9e3081ca PZ |
5804 | /* |
5805 | * update tg->load_weight by folding this cpu's load_avg | |
5806 | */ | |
48a16753 | 5807 | static void __update_blocked_averages_cpu(struct task_group *tg, int cpu) |
9e3081ca | 5808 | { |
48a16753 PT |
5809 | struct sched_entity *se = tg->se[cpu]; |
5810 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu]; | |
9e3081ca | 5811 | |
48a16753 PT |
5812 | /* throttled entities do not contribute to load */ |
5813 | if (throttled_hierarchy(cfs_rq)) | |
5814 | return; | |
9e3081ca | 5815 | |
aff3e498 | 5816 | update_cfs_rq_blocked_load(cfs_rq, 1); |
9e3081ca | 5817 | |
82958366 PT |
5818 | if (se) { |
5819 | update_entity_load_avg(se, 1); | |
5820 | /* | |
5821 | * We pivot on our runnable average having decayed to zero for | |
5822 | * list removal. This generally implies that all our children | |
5823 | * have also been removed (modulo rounding error or bandwidth | |
5824 | * control); however, such cases are rare and we can fix these | |
5825 | * at enqueue. | |
5826 | * | |
5827 | * TODO: fix up out-of-order children on enqueue. | |
5828 | */ | |
5829 | if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running) | |
5830 | list_del_leaf_cfs_rq(cfs_rq); | |
5831 | } else { | |
48a16753 | 5832 | struct rq *rq = rq_of(cfs_rq); |
82958366 PT |
5833 | update_rq_runnable_avg(rq, rq->nr_running); |
5834 | } | |
9e3081ca PZ |
5835 | } |
5836 | ||
48a16753 | 5837 | static void update_blocked_averages(int cpu) |
9e3081ca | 5838 | { |
9e3081ca | 5839 | struct rq *rq = cpu_rq(cpu); |
48a16753 PT |
5840 | struct cfs_rq *cfs_rq; |
5841 | unsigned long flags; | |
9e3081ca | 5842 | |
48a16753 PT |
5843 | raw_spin_lock_irqsave(&rq->lock, flags); |
5844 | update_rq_clock(rq); | |
9763b67f PZ |
5845 | /* |
5846 | * Iterates the task_group tree in a bottom up fashion, see | |
5847 | * list_add_leaf_cfs_rq() for details. | |
5848 | */ | |
64660c86 | 5849 | for_each_leaf_cfs_rq(rq, cfs_rq) { |
48a16753 PT |
5850 | /* |
5851 | * Note: We may want to consider periodically releasing | |
5852 | * rq->lock about these updates so that creating many task | |
5853 | * groups does not result in continually extending hold time. | |
5854 | */ | |
5855 | __update_blocked_averages_cpu(cfs_rq->tg, rq->cpu); | |
64660c86 | 5856 | } |
48a16753 PT |
5857 | |
5858 | raw_spin_unlock_irqrestore(&rq->lock, flags); | |
9e3081ca PZ |
5859 | } |
5860 | ||
9763b67f | 5861 | /* |
68520796 | 5862 | * Compute the hierarchical load factor for cfs_rq and all its ascendants. |
9763b67f PZ |
5863 | * This needs to be done in a top-down fashion because the load of a child |
5864 | * group is a fraction of its parents load. | |
5865 | */ | |
68520796 | 5866 | static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq) |
9763b67f | 5867 | { |
68520796 VD |
5868 | struct rq *rq = rq_of(cfs_rq); |
5869 | struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)]; | |
a35b6466 | 5870 | unsigned long now = jiffies; |
68520796 | 5871 | unsigned long load; |
a35b6466 | 5872 | |
68520796 | 5873 | if (cfs_rq->last_h_load_update == now) |
a35b6466 PZ |
5874 | return; |
5875 | ||
68520796 VD |
5876 | cfs_rq->h_load_next = NULL; |
5877 | for_each_sched_entity(se) { | |
5878 | cfs_rq = cfs_rq_of(se); | |
5879 | cfs_rq->h_load_next = se; | |
5880 | if (cfs_rq->last_h_load_update == now) | |
5881 | break; | |
5882 | } | |
a35b6466 | 5883 | |
68520796 | 5884 | if (!se) { |
7e3115ef | 5885 | cfs_rq->h_load = cfs_rq->runnable_load_avg; |
68520796 VD |
5886 | cfs_rq->last_h_load_update = now; |
5887 | } | |
5888 | ||
5889 | while ((se = cfs_rq->h_load_next) != NULL) { | |
5890 | load = cfs_rq->h_load; | |
5891 | load = div64_ul(load * se->avg.load_avg_contrib, | |
5892 | cfs_rq->runnable_load_avg + 1); | |
5893 | cfs_rq = group_cfs_rq(se); | |
5894 | cfs_rq->h_load = load; | |
5895 | cfs_rq->last_h_load_update = now; | |
5896 | } | |
9763b67f PZ |
5897 | } |
5898 | ||
367456c7 | 5899 | static unsigned long task_h_load(struct task_struct *p) |
230059de | 5900 | { |
367456c7 | 5901 | struct cfs_rq *cfs_rq = task_cfs_rq(p); |
230059de | 5902 | |
68520796 | 5903 | update_cfs_rq_h_load(cfs_rq); |
a003a25b AS |
5904 | return div64_ul(p->se.avg.load_avg_contrib * cfs_rq->h_load, |
5905 | cfs_rq->runnable_load_avg + 1); | |
230059de PZ |
5906 | } |
5907 | #else | |
48a16753 | 5908 | static inline void update_blocked_averages(int cpu) |
9e3081ca PZ |
5909 | { |
5910 | } | |
5911 | ||
367456c7 | 5912 | static unsigned long task_h_load(struct task_struct *p) |
1e3c88bd | 5913 | { |
a003a25b | 5914 | return p->se.avg.load_avg_contrib; |
1e3c88bd | 5915 | } |
230059de | 5916 | #endif |
1e3c88bd | 5917 | |
1e3c88bd | 5918 | /********** Helpers for find_busiest_group ************************/ |
caeb178c RR |
5919 | |
5920 | enum group_type { | |
5921 | group_other = 0, | |
5922 | group_imbalanced, | |
5923 | group_overloaded, | |
5924 | }; | |
5925 | ||
1e3c88bd PZ |
5926 | /* |
5927 | * sg_lb_stats - stats of a sched_group required for load_balancing | |
5928 | */ | |
5929 | struct sg_lb_stats { | |
5930 | unsigned long avg_load; /*Avg load across the CPUs of the group */ | |
5931 | unsigned long group_load; /* Total load over the CPUs of the group */ | |
1e3c88bd | 5932 | unsigned long sum_weighted_load; /* Weighted load of group's tasks */ |
56cf515b | 5933 | unsigned long load_per_task; |
63b2ca30 | 5934 | unsigned long group_capacity; |
8bb5b00c | 5935 | unsigned long group_usage; /* Total usage of the group */ |
147c5fc2 | 5936 | unsigned int sum_nr_running; /* Nr tasks running in the group */ |
147c5fc2 PZ |
5937 | unsigned int idle_cpus; |
5938 | unsigned int group_weight; | |
caeb178c | 5939 | enum group_type group_type; |
ea67821b | 5940 | int group_no_capacity; |
0ec8aa00 PZ |
5941 | #ifdef CONFIG_NUMA_BALANCING |
5942 | unsigned int nr_numa_running; | |
5943 | unsigned int nr_preferred_running; | |
5944 | #endif | |
1e3c88bd PZ |
5945 | }; |
5946 | ||
56cf515b JK |
5947 | /* |
5948 | * sd_lb_stats - Structure to store the statistics of a sched_domain | |
5949 | * during load balancing. | |
5950 | */ | |
5951 | struct sd_lb_stats { | |
5952 | struct sched_group *busiest; /* Busiest group in this sd */ | |
5953 | struct sched_group *local; /* Local group in this sd */ | |
5954 | unsigned long total_load; /* Total load of all groups in sd */ | |
63b2ca30 | 5955 | unsigned long total_capacity; /* Total capacity of all groups in sd */ |
56cf515b JK |
5956 | unsigned long avg_load; /* Average load across all groups in sd */ |
5957 | ||
56cf515b | 5958 | struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */ |
147c5fc2 | 5959 | struct sg_lb_stats local_stat; /* Statistics of the local group */ |
56cf515b JK |
5960 | }; |
5961 | ||
147c5fc2 PZ |
5962 | static inline void init_sd_lb_stats(struct sd_lb_stats *sds) |
5963 | { | |
5964 | /* | |
5965 | * Skimp on the clearing to avoid duplicate work. We can avoid clearing | |
5966 | * local_stat because update_sg_lb_stats() does a full clear/assignment. | |
5967 | * We must however clear busiest_stat::avg_load because | |
5968 | * update_sd_pick_busiest() reads this before assignment. | |
5969 | */ | |
5970 | *sds = (struct sd_lb_stats){ | |
5971 | .busiest = NULL, | |
5972 | .local = NULL, | |
5973 | .total_load = 0UL, | |
63b2ca30 | 5974 | .total_capacity = 0UL, |
147c5fc2 PZ |
5975 | .busiest_stat = { |
5976 | .avg_load = 0UL, | |
caeb178c RR |
5977 | .sum_nr_running = 0, |
5978 | .group_type = group_other, | |
147c5fc2 PZ |
5979 | }, |
5980 | }; | |
5981 | } | |
5982 | ||
1e3c88bd PZ |
5983 | /** |
5984 | * get_sd_load_idx - Obtain the load index for a given sched domain. | |
5985 | * @sd: The sched_domain whose load_idx is to be obtained. | |
ed1b7732 | 5986 | * @idle: The idle status of the CPU for whose sd load_idx is obtained. |
e69f6186 YB |
5987 | * |
5988 | * Return: The load index. | |
1e3c88bd PZ |
5989 | */ |
5990 | static inline int get_sd_load_idx(struct sched_domain *sd, | |
5991 | enum cpu_idle_type idle) | |
5992 | { | |
5993 | int load_idx; | |
5994 | ||
5995 | switch (idle) { | |
5996 | case CPU_NOT_IDLE: | |
5997 | load_idx = sd->busy_idx; | |
5998 | break; | |
5999 | ||
6000 | case CPU_NEWLY_IDLE: | |
6001 | load_idx = sd->newidle_idx; | |
6002 | break; | |
6003 | default: | |
6004 | load_idx = sd->idle_idx; | |
6005 | break; | |
6006 | } | |
6007 | ||
6008 | return load_idx; | |
6009 | } | |
6010 | ||
26bc3c50 | 6011 | static unsigned long default_scale_cpu_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd | 6012 | { |
26bc3c50 VG |
6013 | if ((sd->flags & SD_SHARE_CPUCAPACITY) && (sd->span_weight > 1)) |
6014 | return sd->smt_gain / sd->span_weight; | |
1e3c88bd | 6015 | |
26bc3c50 | 6016 | return SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
6017 | } |
6018 | ||
26bc3c50 | 6019 | unsigned long __weak arch_scale_cpu_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd | 6020 | { |
26bc3c50 | 6021 | return default_scale_cpu_capacity(sd, cpu); |
1e3c88bd PZ |
6022 | } |
6023 | ||
ced549fa | 6024 | static unsigned long scale_rt_capacity(int cpu) |
1e3c88bd PZ |
6025 | { |
6026 | struct rq *rq = cpu_rq(cpu); | |
b5b4860d | 6027 | u64 total, used, age_stamp, avg; |
cadefd3d | 6028 | s64 delta; |
1e3c88bd | 6029 | |
b654f7de PZ |
6030 | /* |
6031 | * Since we're reading these variables without serialization make sure | |
6032 | * we read them once before doing sanity checks on them. | |
6033 | */ | |
6034 | age_stamp = ACCESS_ONCE(rq->age_stamp); | |
6035 | avg = ACCESS_ONCE(rq->rt_avg); | |
cebde6d6 | 6036 | delta = __rq_clock_broken(rq) - age_stamp; |
b654f7de | 6037 | |
cadefd3d PZ |
6038 | if (unlikely(delta < 0)) |
6039 | delta = 0; | |
6040 | ||
6041 | total = sched_avg_period() + delta; | |
aa483808 | 6042 | |
b5b4860d | 6043 | used = div_u64(avg, total); |
1e3c88bd | 6044 | |
b5b4860d VG |
6045 | if (likely(used < SCHED_CAPACITY_SCALE)) |
6046 | return SCHED_CAPACITY_SCALE - used; | |
1e3c88bd | 6047 | |
b5b4860d | 6048 | return 1; |
1e3c88bd PZ |
6049 | } |
6050 | ||
ced549fa | 6051 | static void update_cpu_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd | 6052 | { |
ca8ce3d0 | 6053 | unsigned long capacity = SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
6054 | struct sched_group *sdg = sd->groups; |
6055 | ||
26bc3c50 VG |
6056 | if (sched_feat(ARCH_CAPACITY)) |
6057 | capacity *= arch_scale_cpu_capacity(sd, cpu); | |
6058 | else | |
6059 | capacity *= default_scale_cpu_capacity(sd, cpu); | |
1e3c88bd | 6060 | |
26bc3c50 | 6061 | capacity >>= SCHED_CAPACITY_SHIFT; |
1e3c88bd | 6062 | |
ca6d75e6 | 6063 | cpu_rq(cpu)->cpu_capacity_orig = capacity; |
9d5efe05 | 6064 | |
ced549fa | 6065 | capacity *= scale_rt_capacity(cpu); |
ca8ce3d0 | 6066 | capacity >>= SCHED_CAPACITY_SHIFT; |
1e3c88bd | 6067 | |
ced549fa NP |
6068 | if (!capacity) |
6069 | capacity = 1; | |
1e3c88bd | 6070 | |
ced549fa NP |
6071 | cpu_rq(cpu)->cpu_capacity = capacity; |
6072 | sdg->sgc->capacity = capacity; | |
1e3c88bd PZ |
6073 | } |
6074 | ||
63b2ca30 | 6075 | void update_group_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd PZ |
6076 | { |
6077 | struct sched_domain *child = sd->child; | |
6078 | struct sched_group *group, *sdg = sd->groups; | |
dc7ff76e | 6079 | unsigned long capacity; |
4ec4412e VG |
6080 | unsigned long interval; |
6081 | ||
6082 | interval = msecs_to_jiffies(sd->balance_interval); | |
6083 | interval = clamp(interval, 1UL, max_load_balance_interval); | |
63b2ca30 | 6084 | sdg->sgc->next_update = jiffies + interval; |
1e3c88bd PZ |
6085 | |
6086 | if (!child) { | |
ced549fa | 6087 | update_cpu_capacity(sd, cpu); |
1e3c88bd PZ |
6088 | return; |
6089 | } | |
6090 | ||
dc7ff76e | 6091 | capacity = 0; |
1e3c88bd | 6092 | |
74a5ce20 PZ |
6093 | if (child->flags & SD_OVERLAP) { |
6094 | /* | |
6095 | * SD_OVERLAP domains cannot assume that child groups | |
6096 | * span the current group. | |
6097 | */ | |
6098 | ||
863bffc8 | 6099 | for_each_cpu(cpu, sched_group_cpus(sdg)) { |
63b2ca30 | 6100 | struct sched_group_capacity *sgc; |
9abf24d4 | 6101 | struct rq *rq = cpu_rq(cpu); |
863bffc8 | 6102 | |
9abf24d4 | 6103 | /* |
63b2ca30 | 6104 | * build_sched_domains() -> init_sched_groups_capacity() |
9abf24d4 SD |
6105 | * gets here before we've attached the domains to the |
6106 | * runqueues. | |
6107 | * | |
ced549fa NP |
6108 | * Use capacity_of(), which is set irrespective of domains |
6109 | * in update_cpu_capacity(). | |
9abf24d4 | 6110 | * |
dc7ff76e | 6111 | * This avoids capacity from being 0 and |
9abf24d4 | 6112 | * causing divide-by-zero issues on boot. |
9abf24d4 SD |
6113 | */ |
6114 | if (unlikely(!rq->sd)) { | |
ced549fa | 6115 | capacity += capacity_of(cpu); |
9abf24d4 SD |
6116 | continue; |
6117 | } | |
863bffc8 | 6118 | |
63b2ca30 | 6119 | sgc = rq->sd->groups->sgc; |
63b2ca30 | 6120 | capacity += sgc->capacity; |
863bffc8 | 6121 | } |
74a5ce20 PZ |
6122 | } else { |
6123 | /* | |
6124 | * !SD_OVERLAP domains can assume that child groups | |
6125 | * span the current group. | |
6126 | */ | |
6127 | ||
6128 | group = child->groups; | |
6129 | do { | |
63b2ca30 | 6130 | capacity += group->sgc->capacity; |
74a5ce20 PZ |
6131 | group = group->next; |
6132 | } while (group != child->groups); | |
6133 | } | |
1e3c88bd | 6134 | |
63b2ca30 | 6135 | sdg->sgc->capacity = capacity; |
1e3c88bd PZ |
6136 | } |
6137 | ||
9d5efe05 | 6138 | /* |
ea67821b VG |
6139 | * Check whether the capacity of the rq has been noticeably reduced by side |
6140 | * activity. The imbalance_pct is used for the threshold. | |
6141 | * Return true is the capacity is reduced | |
9d5efe05 SV |
6142 | */ |
6143 | static inline int | |
ea67821b | 6144 | check_cpu_capacity(struct rq *rq, struct sched_domain *sd) |
9d5efe05 | 6145 | { |
ea67821b VG |
6146 | return ((rq->cpu_capacity * sd->imbalance_pct) < |
6147 | (rq->cpu_capacity_orig * 100)); | |
9d5efe05 SV |
6148 | } |
6149 | ||
30ce5dab PZ |
6150 | /* |
6151 | * Group imbalance indicates (and tries to solve) the problem where balancing | |
6152 | * groups is inadequate due to tsk_cpus_allowed() constraints. | |
6153 | * | |
6154 | * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a | |
6155 | * cpumask covering 1 cpu of the first group and 3 cpus of the second group. | |
6156 | * Something like: | |
6157 | * | |
6158 | * { 0 1 2 3 } { 4 5 6 7 } | |
6159 | * * * * * | |
6160 | * | |
6161 | * If we were to balance group-wise we'd place two tasks in the first group and | |
6162 | * two tasks in the second group. Clearly this is undesired as it will overload | |
6163 | * cpu 3 and leave one of the cpus in the second group unused. | |
6164 | * | |
6165 | * The current solution to this issue is detecting the skew in the first group | |
6263322c PZ |
6166 | * by noticing the lower domain failed to reach balance and had difficulty |
6167 | * moving tasks due to affinity constraints. | |
30ce5dab PZ |
6168 | * |
6169 | * When this is so detected; this group becomes a candidate for busiest; see | |
ed1b7732 | 6170 | * update_sd_pick_busiest(). And calculate_imbalance() and |
6263322c | 6171 | * find_busiest_group() avoid some of the usual balance conditions to allow it |
30ce5dab PZ |
6172 | * to create an effective group imbalance. |
6173 | * | |
6174 | * This is a somewhat tricky proposition since the next run might not find the | |
6175 | * group imbalance and decide the groups need to be balanced again. A most | |
6176 | * subtle and fragile situation. | |
6177 | */ | |
6178 | ||
6263322c | 6179 | static inline int sg_imbalanced(struct sched_group *group) |
30ce5dab | 6180 | { |
63b2ca30 | 6181 | return group->sgc->imbalance; |
30ce5dab PZ |
6182 | } |
6183 | ||
b37d9316 | 6184 | /* |
ea67821b VG |
6185 | * group_has_capacity returns true if the group has spare capacity that could |
6186 | * be used by some tasks. | |
6187 | * We consider that a group has spare capacity if the * number of task is | |
6188 | * smaller than the number of CPUs or if the usage is lower than the available | |
6189 | * capacity for CFS tasks. | |
6190 | * For the latter, we use a threshold to stabilize the state, to take into | |
6191 | * account the variance of the tasks' load and to return true if the available | |
6192 | * capacity in meaningful for the load balancer. | |
6193 | * As an example, an available capacity of 1% can appear but it doesn't make | |
6194 | * any benefit for the load balance. | |
b37d9316 | 6195 | */ |
ea67821b VG |
6196 | static inline bool |
6197 | group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs) | |
b37d9316 | 6198 | { |
ea67821b VG |
6199 | if (sgs->sum_nr_running < sgs->group_weight) |
6200 | return true; | |
c61037e9 | 6201 | |
ea67821b VG |
6202 | if ((sgs->group_capacity * 100) > |
6203 | (sgs->group_usage * env->sd->imbalance_pct)) | |
6204 | return true; | |
b37d9316 | 6205 | |
ea67821b VG |
6206 | return false; |
6207 | } | |
6208 | ||
6209 | /* | |
6210 | * group_is_overloaded returns true if the group has more tasks than it can | |
6211 | * handle. | |
6212 | * group_is_overloaded is not equals to !group_has_capacity because a group | |
6213 | * with the exact right number of tasks, has no more spare capacity but is not | |
6214 | * overloaded so both group_has_capacity and group_is_overloaded return | |
6215 | * false. | |
6216 | */ | |
6217 | static inline bool | |
6218 | group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs) | |
6219 | { | |
6220 | if (sgs->sum_nr_running <= sgs->group_weight) | |
6221 | return false; | |
b37d9316 | 6222 | |
ea67821b VG |
6223 | if ((sgs->group_capacity * 100) < |
6224 | (sgs->group_usage * env->sd->imbalance_pct)) | |
6225 | return true; | |
b37d9316 | 6226 | |
ea67821b | 6227 | return false; |
b37d9316 PZ |
6228 | } |
6229 | ||
ea67821b VG |
6230 | static enum group_type group_classify(struct lb_env *env, |
6231 | struct sched_group *group, | |
6232 | struct sg_lb_stats *sgs) | |
caeb178c | 6233 | { |
ea67821b | 6234 | if (sgs->group_no_capacity) |
caeb178c RR |
6235 | return group_overloaded; |
6236 | ||
6237 | if (sg_imbalanced(group)) | |
6238 | return group_imbalanced; | |
6239 | ||
6240 | return group_other; | |
6241 | } | |
6242 | ||
1e3c88bd PZ |
6243 | /** |
6244 | * update_sg_lb_stats - Update sched_group's statistics for load balancing. | |
cd96891d | 6245 | * @env: The load balancing environment. |
1e3c88bd | 6246 | * @group: sched_group whose statistics are to be updated. |
1e3c88bd | 6247 | * @load_idx: Load index of sched_domain of this_cpu for load calc. |
1e3c88bd | 6248 | * @local_group: Does group contain this_cpu. |
1e3c88bd | 6249 | * @sgs: variable to hold the statistics for this group. |
cd3bd4e6 | 6250 | * @overload: Indicate more than one runnable task for any CPU. |
1e3c88bd | 6251 | */ |
bd939f45 PZ |
6252 | static inline void update_sg_lb_stats(struct lb_env *env, |
6253 | struct sched_group *group, int load_idx, | |
4486edd1 TC |
6254 | int local_group, struct sg_lb_stats *sgs, |
6255 | bool *overload) | |
1e3c88bd | 6256 | { |
30ce5dab | 6257 | unsigned long load; |
bd939f45 | 6258 | int i; |
1e3c88bd | 6259 | |
b72ff13c PZ |
6260 | memset(sgs, 0, sizeof(*sgs)); |
6261 | ||
b9403130 | 6262 | for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { |
1e3c88bd PZ |
6263 | struct rq *rq = cpu_rq(i); |
6264 | ||
1e3c88bd | 6265 | /* Bias balancing toward cpus of our domain */ |
6263322c | 6266 | if (local_group) |
04f733b4 | 6267 | load = target_load(i, load_idx); |
6263322c | 6268 | else |
1e3c88bd | 6269 | load = source_load(i, load_idx); |
1e3c88bd PZ |
6270 | |
6271 | sgs->group_load += load; | |
8bb5b00c | 6272 | sgs->group_usage += get_cpu_usage(i); |
65fdac08 | 6273 | sgs->sum_nr_running += rq->cfs.h_nr_running; |
4486edd1 TC |
6274 | |
6275 | if (rq->nr_running > 1) | |
6276 | *overload = true; | |
6277 | ||
0ec8aa00 PZ |
6278 | #ifdef CONFIG_NUMA_BALANCING |
6279 | sgs->nr_numa_running += rq->nr_numa_running; | |
6280 | sgs->nr_preferred_running += rq->nr_preferred_running; | |
6281 | #endif | |
1e3c88bd | 6282 | sgs->sum_weighted_load += weighted_cpuload(i); |
aae6d3dd SS |
6283 | if (idle_cpu(i)) |
6284 | sgs->idle_cpus++; | |
1e3c88bd PZ |
6285 | } |
6286 | ||
63b2ca30 NP |
6287 | /* Adjust by relative CPU capacity of the group */ |
6288 | sgs->group_capacity = group->sgc->capacity; | |
ca8ce3d0 | 6289 | sgs->avg_load = (sgs->group_load*SCHED_CAPACITY_SCALE) / sgs->group_capacity; |
1e3c88bd | 6290 | |
dd5feea1 | 6291 | if (sgs->sum_nr_running) |
38d0f770 | 6292 | sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; |
1e3c88bd | 6293 | |
aae6d3dd | 6294 | sgs->group_weight = group->group_weight; |
b37d9316 | 6295 | |
ea67821b VG |
6296 | sgs->group_no_capacity = group_is_overloaded(env, sgs); |
6297 | sgs->group_type = group_classify(env, group, sgs); | |
1e3c88bd PZ |
6298 | } |
6299 | ||
532cb4c4 MN |
6300 | /** |
6301 | * update_sd_pick_busiest - return 1 on busiest group | |
cd96891d | 6302 | * @env: The load balancing environment. |
532cb4c4 MN |
6303 | * @sds: sched_domain statistics |
6304 | * @sg: sched_group candidate to be checked for being the busiest | |
b6b12294 | 6305 | * @sgs: sched_group statistics |
532cb4c4 MN |
6306 | * |
6307 | * Determine if @sg is a busier group than the previously selected | |
6308 | * busiest group. | |
e69f6186 YB |
6309 | * |
6310 | * Return: %true if @sg is a busier group than the previously selected | |
6311 | * busiest group. %false otherwise. | |
532cb4c4 | 6312 | */ |
bd939f45 | 6313 | static bool update_sd_pick_busiest(struct lb_env *env, |
532cb4c4 MN |
6314 | struct sd_lb_stats *sds, |
6315 | struct sched_group *sg, | |
bd939f45 | 6316 | struct sg_lb_stats *sgs) |
532cb4c4 | 6317 | { |
caeb178c | 6318 | struct sg_lb_stats *busiest = &sds->busiest_stat; |
532cb4c4 | 6319 | |
caeb178c | 6320 | if (sgs->group_type > busiest->group_type) |
532cb4c4 MN |
6321 | return true; |
6322 | ||
caeb178c RR |
6323 | if (sgs->group_type < busiest->group_type) |
6324 | return false; | |
6325 | ||
6326 | if (sgs->avg_load <= busiest->avg_load) | |
6327 | return false; | |
6328 | ||
6329 | /* This is the busiest node in its class. */ | |
6330 | if (!(env->sd->flags & SD_ASYM_PACKING)) | |
532cb4c4 MN |
6331 | return true; |
6332 | ||
6333 | /* | |
6334 | * ASYM_PACKING needs to move all the work to the lowest | |
6335 | * numbered CPUs in the group, therefore mark all groups | |
6336 | * higher than ourself as busy. | |
6337 | */ | |
caeb178c | 6338 | if (sgs->sum_nr_running && env->dst_cpu < group_first_cpu(sg)) { |
532cb4c4 MN |
6339 | if (!sds->busiest) |
6340 | return true; | |
6341 | ||
6342 | if (group_first_cpu(sds->busiest) > group_first_cpu(sg)) | |
6343 | return true; | |
6344 | } | |
6345 | ||
6346 | return false; | |
6347 | } | |
6348 | ||
0ec8aa00 PZ |
6349 | #ifdef CONFIG_NUMA_BALANCING |
6350 | static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) | |
6351 | { | |
6352 | if (sgs->sum_nr_running > sgs->nr_numa_running) | |
6353 | return regular; | |
6354 | if (sgs->sum_nr_running > sgs->nr_preferred_running) | |
6355 | return remote; | |
6356 | return all; | |
6357 | } | |
6358 | ||
6359 | static inline enum fbq_type fbq_classify_rq(struct rq *rq) | |
6360 | { | |
6361 | if (rq->nr_running > rq->nr_numa_running) | |
6362 | return regular; | |
6363 | if (rq->nr_running > rq->nr_preferred_running) | |
6364 | return remote; | |
6365 | return all; | |
6366 | } | |
6367 | #else | |
6368 | static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) | |
6369 | { | |
6370 | return all; | |
6371 | } | |
6372 | ||
6373 | static inline enum fbq_type fbq_classify_rq(struct rq *rq) | |
6374 | { | |
6375 | return regular; | |
6376 | } | |
6377 | #endif /* CONFIG_NUMA_BALANCING */ | |
6378 | ||
1e3c88bd | 6379 | /** |
461819ac | 6380 | * update_sd_lb_stats - Update sched_domain's statistics for load balancing. |
cd96891d | 6381 | * @env: The load balancing environment. |
1e3c88bd PZ |
6382 | * @sds: variable to hold the statistics for this sched_domain. |
6383 | */ | |
0ec8aa00 | 6384 | static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds) |
1e3c88bd | 6385 | { |
bd939f45 PZ |
6386 | struct sched_domain *child = env->sd->child; |
6387 | struct sched_group *sg = env->sd->groups; | |
56cf515b | 6388 | struct sg_lb_stats tmp_sgs; |
1e3c88bd | 6389 | int load_idx, prefer_sibling = 0; |
4486edd1 | 6390 | bool overload = false; |
1e3c88bd PZ |
6391 | |
6392 | if (child && child->flags & SD_PREFER_SIBLING) | |
6393 | prefer_sibling = 1; | |
6394 | ||
bd939f45 | 6395 | load_idx = get_sd_load_idx(env->sd, env->idle); |
1e3c88bd PZ |
6396 | |
6397 | do { | |
56cf515b | 6398 | struct sg_lb_stats *sgs = &tmp_sgs; |
1e3c88bd PZ |
6399 | int local_group; |
6400 | ||
bd939f45 | 6401 | local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg)); |
56cf515b JK |
6402 | if (local_group) { |
6403 | sds->local = sg; | |
6404 | sgs = &sds->local_stat; | |
b72ff13c PZ |
6405 | |
6406 | if (env->idle != CPU_NEWLY_IDLE || | |
63b2ca30 NP |
6407 | time_after_eq(jiffies, sg->sgc->next_update)) |
6408 | update_group_capacity(env->sd, env->dst_cpu); | |
56cf515b | 6409 | } |
1e3c88bd | 6410 | |
4486edd1 TC |
6411 | update_sg_lb_stats(env, sg, load_idx, local_group, sgs, |
6412 | &overload); | |
1e3c88bd | 6413 | |
b72ff13c PZ |
6414 | if (local_group) |
6415 | goto next_group; | |
6416 | ||
1e3c88bd PZ |
6417 | /* |
6418 | * In case the child domain prefers tasks go to siblings | |
ea67821b | 6419 | * first, lower the sg capacity so that we'll try |
75dd321d NR |
6420 | * and move all the excess tasks away. We lower the capacity |
6421 | * of a group only if the local group has the capacity to fit | |
ea67821b VG |
6422 | * these excess tasks. The extra check prevents the case where |
6423 | * you always pull from the heaviest group when it is already | |
6424 | * under-utilized (possible with a large weight task outweighs | |
6425 | * the tasks on the system). | |
1e3c88bd | 6426 | */ |
b72ff13c | 6427 | if (prefer_sibling && sds->local && |
ea67821b VG |
6428 | group_has_capacity(env, &sds->local_stat) && |
6429 | (sgs->sum_nr_running > 1)) { | |
6430 | sgs->group_no_capacity = 1; | |
6431 | sgs->group_type = group_overloaded; | |
cb0b9f24 | 6432 | } |
1e3c88bd | 6433 | |
b72ff13c | 6434 | if (update_sd_pick_busiest(env, sds, sg, sgs)) { |
532cb4c4 | 6435 | sds->busiest = sg; |
56cf515b | 6436 | sds->busiest_stat = *sgs; |
1e3c88bd PZ |
6437 | } |
6438 | ||
b72ff13c PZ |
6439 | next_group: |
6440 | /* Now, start updating sd_lb_stats */ | |
6441 | sds->total_load += sgs->group_load; | |
63b2ca30 | 6442 | sds->total_capacity += sgs->group_capacity; |
b72ff13c | 6443 | |
532cb4c4 | 6444 | sg = sg->next; |
bd939f45 | 6445 | } while (sg != env->sd->groups); |
0ec8aa00 PZ |
6446 | |
6447 | if (env->sd->flags & SD_NUMA) | |
6448 | env->fbq_type = fbq_classify_group(&sds->busiest_stat); | |
4486edd1 TC |
6449 | |
6450 | if (!env->sd->parent) { | |
6451 | /* update overload indicator if we are at root domain */ | |
6452 | if (env->dst_rq->rd->overload != overload) | |
6453 | env->dst_rq->rd->overload = overload; | |
6454 | } | |
6455 | ||
532cb4c4 MN |
6456 | } |
6457 | ||
532cb4c4 MN |
6458 | /** |
6459 | * check_asym_packing - Check to see if the group is packed into the | |
6460 | * sched doman. | |
6461 | * | |
6462 | * This is primarily intended to used at the sibling level. Some | |
6463 | * cores like POWER7 prefer to use lower numbered SMT threads. In the | |
6464 | * case of POWER7, it can move to lower SMT modes only when higher | |
6465 | * threads are idle. When in lower SMT modes, the threads will | |
6466 | * perform better since they share less core resources. Hence when we | |
6467 | * have idle threads, we want them to be the higher ones. | |
6468 | * | |
6469 | * This packing function is run on idle threads. It checks to see if | |
6470 | * the busiest CPU in this domain (core in the P7 case) has a higher | |
6471 | * CPU number than the packing function is being run on. Here we are | |
6472 | * assuming lower CPU number will be equivalent to lower a SMT thread | |
6473 | * number. | |
6474 | * | |
e69f6186 | 6475 | * Return: 1 when packing is required and a task should be moved to |
b6b12294 MN |
6476 | * this CPU. The amount of the imbalance is returned in *imbalance. |
6477 | * | |
cd96891d | 6478 | * @env: The load balancing environment. |
532cb4c4 | 6479 | * @sds: Statistics of the sched_domain which is to be packed |
532cb4c4 | 6480 | */ |
bd939f45 | 6481 | static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds) |
532cb4c4 MN |
6482 | { |
6483 | int busiest_cpu; | |
6484 | ||
bd939f45 | 6485 | if (!(env->sd->flags & SD_ASYM_PACKING)) |
532cb4c4 MN |
6486 | return 0; |
6487 | ||
6488 | if (!sds->busiest) | |
6489 | return 0; | |
6490 | ||
6491 | busiest_cpu = group_first_cpu(sds->busiest); | |
bd939f45 | 6492 | if (env->dst_cpu > busiest_cpu) |
532cb4c4 MN |
6493 | return 0; |
6494 | ||
bd939f45 | 6495 | env->imbalance = DIV_ROUND_CLOSEST( |
63b2ca30 | 6496 | sds->busiest_stat.avg_load * sds->busiest_stat.group_capacity, |
ca8ce3d0 | 6497 | SCHED_CAPACITY_SCALE); |
bd939f45 | 6498 | |
532cb4c4 | 6499 | return 1; |
1e3c88bd PZ |
6500 | } |
6501 | ||
6502 | /** | |
6503 | * fix_small_imbalance - Calculate the minor imbalance that exists | |
6504 | * amongst the groups of a sched_domain, during | |
6505 | * load balancing. | |
cd96891d | 6506 | * @env: The load balancing environment. |
1e3c88bd | 6507 | * @sds: Statistics of the sched_domain whose imbalance is to be calculated. |
1e3c88bd | 6508 | */ |
bd939f45 PZ |
6509 | static inline |
6510 | void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds) | |
1e3c88bd | 6511 | { |
63b2ca30 | 6512 | unsigned long tmp, capa_now = 0, capa_move = 0; |
1e3c88bd | 6513 | unsigned int imbn = 2; |
dd5feea1 | 6514 | unsigned long scaled_busy_load_per_task; |
56cf515b | 6515 | struct sg_lb_stats *local, *busiest; |
1e3c88bd | 6516 | |
56cf515b JK |
6517 | local = &sds->local_stat; |
6518 | busiest = &sds->busiest_stat; | |
1e3c88bd | 6519 | |
56cf515b JK |
6520 | if (!local->sum_nr_running) |
6521 | local->load_per_task = cpu_avg_load_per_task(env->dst_cpu); | |
6522 | else if (busiest->load_per_task > local->load_per_task) | |
6523 | imbn = 1; | |
dd5feea1 | 6524 | |
56cf515b | 6525 | scaled_busy_load_per_task = |
ca8ce3d0 | 6526 | (busiest->load_per_task * SCHED_CAPACITY_SCALE) / |
63b2ca30 | 6527 | busiest->group_capacity; |
56cf515b | 6528 | |
3029ede3 VD |
6529 | if (busiest->avg_load + scaled_busy_load_per_task >= |
6530 | local->avg_load + (scaled_busy_load_per_task * imbn)) { | |
56cf515b | 6531 | env->imbalance = busiest->load_per_task; |
1e3c88bd PZ |
6532 | return; |
6533 | } | |
6534 | ||
6535 | /* | |
6536 | * OK, we don't have enough imbalance to justify moving tasks, | |
ced549fa | 6537 | * however we may be able to increase total CPU capacity used by |
1e3c88bd PZ |
6538 | * moving them. |
6539 | */ | |
6540 | ||
63b2ca30 | 6541 | capa_now += busiest->group_capacity * |
56cf515b | 6542 | min(busiest->load_per_task, busiest->avg_load); |
63b2ca30 | 6543 | capa_now += local->group_capacity * |
56cf515b | 6544 | min(local->load_per_task, local->avg_load); |
ca8ce3d0 | 6545 | capa_now /= SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
6546 | |
6547 | /* Amount of load we'd subtract */ | |
a2cd4260 | 6548 | if (busiest->avg_load > scaled_busy_load_per_task) { |
63b2ca30 | 6549 | capa_move += busiest->group_capacity * |
56cf515b | 6550 | min(busiest->load_per_task, |
a2cd4260 | 6551 | busiest->avg_load - scaled_busy_load_per_task); |
56cf515b | 6552 | } |
1e3c88bd PZ |
6553 | |
6554 | /* Amount of load we'd add */ | |
63b2ca30 | 6555 | if (busiest->avg_load * busiest->group_capacity < |
ca8ce3d0 | 6556 | busiest->load_per_task * SCHED_CAPACITY_SCALE) { |
63b2ca30 NP |
6557 | tmp = (busiest->avg_load * busiest->group_capacity) / |
6558 | local->group_capacity; | |
56cf515b | 6559 | } else { |
ca8ce3d0 | 6560 | tmp = (busiest->load_per_task * SCHED_CAPACITY_SCALE) / |
63b2ca30 | 6561 | local->group_capacity; |
56cf515b | 6562 | } |
63b2ca30 | 6563 | capa_move += local->group_capacity * |
3ae11c90 | 6564 | min(local->load_per_task, local->avg_load + tmp); |
ca8ce3d0 | 6565 | capa_move /= SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
6566 | |
6567 | /* Move if we gain throughput */ | |
63b2ca30 | 6568 | if (capa_move > capa_now) |
56cf515b | 6569 | env->imbalance = busiest->load_per_task; |
1e3c88bd PZ |
6570 | } |
6571 | ||
6572 | /** | |
6573 | * calculate_imbalance - Calculate the amount of imbalance present within the | |
6574 | * groups of a given sched_domain during load balance. | |
bd939f45 | 6575 | * @env: load balance environment |
1e3c88bd | 6576 | * @sds: statistics of the sched_domain whose imbalance is to be calculated. |
1e3c88bd | 6577 | */ |
bd939f45 | 6578 | static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds) |
1e3c88bd | 6579 | { |
dd5feea1 | 6580 | unsigned long max_pull, load_above_capacity = ~0UL; |
56cf515b JK |
6581 | struct sg_lb_stats *local, *busiest; |
6582 | ||
6583 | local = &sds->local_stat; | |
56cf515b | 6584 | busiest = &sds->busiest_stat; |
dd5feea1 | 6585 | |
caeb178c | 6586 | if (busiest->group_type == group_imbalanced) { |
30ce5dab PZ |
6587 | /* |
6588 | * In the group_imb case we cannot rely on group-wide averages | |
6589 | * to ensure cpu-load equilibrium, look at wider averages. XXX | |
6590 | */ | |
56cf515b JK |
6591 | busiest->load_per_task = |
6592 | min(busiest->load_per_task, sds->avg_load); | |
dd5feea1 SS |
6593 | } |
6594 | ||
1e3c88bd PZ |
6595 | /* |
6596 | * In the presence of smp nice balancing, certain scenarios can have | |
6597 | * max load less than avg load(as we skip the groups at or below | |
ced549fa | 6598 | * its cpu_capacity, while calculating max_load..) |
1e3c88bd | 6599 | */ |
b1885550 VD |
6600 | if (busiest->avg_load <= sds->avg_load || |
6601 | local->avg_load >= sds->avg_load) { | |
bd939f45 PZ |
6602 | env->imbalance = 0; |
6603 | return fix_small_imbalance(env, sds); | |
1e3c88bd PZ |
6604 | } |
6605 | ||
9a5d9ba6 PZ |
6606 | /* |
6607 | * If there aren't any idle cpus, avoid creating some. | |
6608 | */ | |
6609 | if (busiest->group_type == group_overloaded && | |
6610 | local->group_type == group_overloaded) { | |
ea67821b VG |
6611 | load_above_capacity = busiest->sum_nr_running * |
6612 | SCHED_LOAD_SCALE; | |
6613 | if (load_above_capacity > busiest->group_capacity) | |
6614 | load_above_capacity -= busiest->group_capacity; | |
6615 | else | |
6616 | load_above_capacity = ~0UL; | |
dd5feea1 SS |
6617 | } |
6618 | ||
6619 | /* | |
6620 | * We're trying to get all the cpus to the average_load, so we don't | |
6621 | * want to push ourselves above the average load, nor do we wish to | |
6622 | * reduce the max loaded cpu below the average load. At the same time, | |
6623 | * we also don't want to reduce the group load below the group capacity | |
6624 | * (so that we can implement power-savings policies etc). Thus we look | |
6625 | * for the minimum possible imbalance. | |
dd5feea1 | 6626 | */ |
30ce5dab | 6627 | max_pull = min(busiest->avg_load - sds->avg_load, load_above_capacity); |
1e3c88bd PZ |
6628 | |
6629 | /* How much load to actually move to equalise the imbalance */ | |
56cf515b | 6630 | env->imbalance = min( |
63b2ca30 NP |
6631 | max_pull * busiest->group_capacity, |
6632 | (sds->avg_load - local->avg_load) * local->group_capacity | |
ca8ce3d0 | 6633 | ) / SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
6634 | |
6635 | /* | |
6636 | * if *imbalance is less than the average load per runnable task | |
25985edc | 6637 | * there is no guarantee that any tasks will be moved so we'll have |
1e3c88bd PZ |
6638 | * a think about bumping its value to force at least one task to be |
6639 | * moved | |
6640 | */ | |
56cf515b | 6641 | if (env->imbalance < busiest->load_per_task) |
bd939f45 | 6642 | return fix_small_imbalance(env, sds); |
1e3c88bd | 6643 | } |
fab47622 | 6644 | |
1e3c88bd PZ |
6645 | /******* find_busiest_group() helpers end here *********************/ |
6646 | ||
6647 | /** | |
6648 | * find_busiest_group - Returns the busiest group within the sched_domain | |
6649 | * if there is an imbalance. If there isn't an imbalance, and | |
6650 | * the user has opted for power-savings, it returns a group whose | |
6651 | * CPUs can be put to idle by rebalancing those tasks elsewhere, if | |
6652 | * such a group exists. | |
6653 | * | |
6654 | * Also calculates the amount of weighted load which should be moved | |
6655 | * to restore balance. | |
6656 | * | |
cd96891d | 6657 | * @env: The load balancing environment. |
1e3c88bd | 6658 | * |
e69f6186 | 6659 | * Return: - The busiest group if imbalance exists. |
1e3c88bd PZ |
6660 | * - If no imbalance and user has opted for power-savings balance, |
6661 | * return the least loaded group whose CPUs can be | |
6662 | * put to idle by rebalancing its tasks onto our group. | |
6663 | */ | |
56cf515b | 6664 | static struct sched_group *find_busiest_group(struct lb_env *env) |
1e3c88bd | 6665 | { |
56cf515b | 6666 | struct sg_lb_stats *local, *busiest; |
1e3c88bd PZ |
6667 | struct sd_lb_stats sds; |
6668 | ||
147c5fc2 | 6669 | init_sd_lb_stats(&sds); |
1e3c88bd PZ |
6670 | |
6671 | /* | |
6672 | * Compute the various statistics relavent for load balancing at | |
6673 | * this level. | |
6674 | */ | |
23f0d209 | 6675 | update_sd_lb_stats(env, &sds); |
56cf515b JK |
6676 | local = &sds.local_stat; |
6677 | busiest = &sds.busiest_stat; | |
1e3c88bd | 6678 | |
ea67821b | 6679 | /* ASYM feature bypasses nice load balance check */ |
bd939f45 PZ |
6680 | if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) && |
6681 | check_asym_packing(env, &sds)) | |
532cb4c4 MN |
6682 | return sds.busiest; |
6683 | ||
cc57aa8f | 6684 | /* There is no busy sibling group to pull tasks from */ |
56cf515b | 6685 | if (!sds.busiest || busiest->sum_nr_running == 0) |
1e3c88bd PZ |
6686 | goto out_balanced; |
6687 | ||
ca8ce3d0 NP |
6688 | sds.avg_load = (SCHED_CAPACITY_SCALE * sds.total_load) |
6689 | / sds.total_capacity; | |
b0432d8f | 6690 | |
866ab43e PZ |
6691 | /* |
6692 | * If the busiest group is imbalanced the below checks don't | |
30ce5dab | 6693 | * work because they assume all things are equal, which typically |
866ab43e PZ |
6694 | * isn't true due to cpus_allowed constraints and the like. |
6695 | */ | |
caeb178c | 6696 | if (busiest->group_type == group_imbalanced) |
866ab43e PZ |
6697 | goto force_balance; |
6698 | ||
cc57aa8f | 6699 | /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */ |
ea67821b VG |
6700 | if (env->idle == CPU_NEWLY_IDLE && group_has_capacity(env, local) && |
6701 | busiest->group_no_capacity) | |
fab47622 NR |
6702 | goto force_balance; |
6703 | ||
cc57aa8f | 6704 | /* |
9c58c79a | 6705 | * If the local group is busier than the selected busiest group |
cc57aa8f PZ |
6706 | * don't try and pull any tasks. |
6707 | */ | |
56cf515b | 6708 | if (local->avg_load >= busiest->avg_load) |
1e3c88bd PZ |
6709 | goto out_balanced; |
6710 | ||
cc57aa8f PZ |
6711 | /* |
6712 | * Don't pull any tasks if this group is already above the domain | |
6713 | * average load. | |
6714 | */ | |
56cf515b | 6715 | if (local->avg_load >= sds.avg_load) |
1e3c88bd PZ |
6716 | goto out_balanced; |
6717 | ||
bd939f45 | 6718 | if (env->idle == CPU_IDLE) { |
aae6d3dd | 6719 | /* |
43f4d666 VG |
6720 | * This cpu is idle. If the busiest group is not overloaded |
6721 | * and there is no imbalance between this and busiest group | |
6722 | * wrt idle cpus, it is balanced. The imbalance becomes | |
6723 | * significant if the diff is greater than 1 otherwise we | |
6724 | * might end up to just move the imbalance on another group | |
aae6d3dd | 6725 | */ |
43f4d666 VG |
6726 | if ((busiest->group_type != group_overloaded) && |
6727 | (local->idle_cpus <= (busiest->idle_cpus + 1))) | |
aae6d3dd | 6728 | goto out_balanced; |
c186fafe PZ |
6729 | } else { |
6730 | /* | |
6731 | * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use | |
6732 | * imbalance_pct to be conservative. | |
6733 | */ | |
56cf515b JK |
6734 | if (100 * busiest->avg_load <= |
6735 | env->sd->imbalance_pct * local->avg_load) | |
c186fafe | 6736 | goto out_balanced; |
aae6d3dd | 6737 | } |
1e3c88bd | 6738 | |
fab47622 | 6739 | force_balance: |
1e3c88bd | 6740 | /* Looks like there is an imbalance. Compute it */ |
bd939f45 | 6741 | calculate_imbalance(env, &sds); |
1e3c88bd PZ |
6742 | return sds.busiest; |
6743 | ||
6744 | out_balanced: | |
bd939f45 | 6745 | env->imbalance = 0; |
1e3c88bd PZ |
6746 | return NULL; |
6747 | } | |
6748 | ||
6749 | /* | |
6750 | * find_busiest_queue - find the busiest runqueue among the cpus in group. | |
6751 | */ | |
bd939f45 | 6752 | static struct rq *find_busiest_queue(struct lb_env *env, |
b9403130 | 6753 | struct sched_group *group) |
1e3c88bd PZ |
6754 | { |
6755 | struct rq *busiest = NULL, *rq; | |
ced549fa | 6756 | unsigned long busiest_load = 0, busiest_capacity = 1; |
1e3c88bd PZ |
6757 | int i; |
6758 | ||
6906a408 | 6759 | for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { |
ea67821b | 6760 | unsigned long capacity, wl; |
0ec8aa00 PZ |
6761 | enum fbq_type rt; |
6762 | ||
6763 | rq = cpu_rq(i); | |
6764 | rt = fbq_classify_rq(rq); | |
1e3c88bd | 6765 | |
0ec8aa00 PZ |
6766 | /* |
6767 | * We classify groups/runqueues into three groups: | |
6768 | * - regular: there are !numa tasks | |
6769 | * - remote: there are numa tasks that run on the 'wrong' node | |
6770 | * - all: there is no distinction | |
6771 | * | |
6772 | * In order to avoid migrating ideally placed numa tasks, | |
6773 | * ignore those when there's better options. | |
6774 | * | |
6775 | * If we ignore the actual busiest queue to migrate another | |
6776 | * task, the next balance pass can still reduce the busiest | |
6777 | * queue by moving tasks around inside the node. | |
6778 | * | |
6779 | * If we cannot move enough load due to this classification | |
6780 | * the next pass will adjust the group classification and | |
6781 | * allow migration of more tasks. | |
6782 | * | |
6783 | * Both cases only affect the total convergence complexity. | |
6784 | */ | |
6785 | if (rt > env->fbq_type) | |
6786 | continue; | |
6787 | ||
ced549fa | 6788 | capacity = capacity_of(i); |
9d5efe05 | 6789 | |
6e40f5bb | 6790 | wl = weighted_cpuload(i); |
1e3c88bd | 6791 | |
6e40f5bb TG |
6792 | /* |
6793 | * When comparing with imbalance, use weighted_cpuload() | |
ced549fa | 6794 | * which is not scaled with the cpu capacity. |
6e40f5bb | 6795 | */ |
ea67821b VG |
6796 | |
6797 | if (rq->nr_running == 1 && wl > env->imbalance && | |
6798 | !check_cpu_capacity(rq, env->sd)) | |
1e3c88bd PZ |
6799 | continue; |
6800 | ||
6e40f5bb TG |
6801 | /* |
6802 | * For the load comparisons with the other cpu's, consider | |
ced549fa NP |
6803 | * the weighted_cpuload() scaled with the cpu capacity, so |
6804 | * that the load can be moved away from the cpu that is | |
6805 | * potentially running at a lower capacity. | |
95a79b80 | 6806 | * |
ced549fa | 6807 | * Thus we're looking for max(wl_i / capacity_i), crosswise |
95a79b80 | 6808 | * multiplication to rid ourselves of the division works out |
ced549fa NP |
6809 | * to: wl_i * capacity_j > wl_j * capacity_i; where j is |
6810 | * our previous maximum. | |
6e40f5bb | 6811 | */ |
ced549fa | 6812 | if (wl * busiest_capacity > busiest_load * capacity) { |
95a79b80 | 6813 | busiest_load = wl; |
ced549fa | 6814 | busiest_capacity = capacity; |
1e3c88bd PZ |
6815 | busiest = rq; |
6816 | } | |
6817 | } | |
6818 | ||
6819 | return busiest; | |
6820 | } | |
6821 | ||
6822 | /* | |
6823 | * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but | |
6824 | * so long as it is large enough. | |
6825 | */ | |
6826 | #define MAX_PINNED_INTERVAL 512 | |
6827 | ||
6828 | /* Working cpumask for load_balance and load_balance_newidle. */ | |
e6252c3e | 6829 | DEFINE_PER_CPU(cpumask_var_t, load_balance_mask); |
1e3c88bd | 6830 | |
bd939f45 | 6831 | static int need_active_balance(struct lb_env *env) |
1af3ed3d | 6832 | { |
bd939f45 PZ |
6833 | struct sched_domain *sd = env->sd; |
6834 | ||
6835 | if (env->idle == CPU_NEWLY_IDLE) { | |
532cb4c4 MN |
6836 | |
6837 | /* | |
6838 | * ASYM_PACKING needs to force migrate tasks from busy but | |
6839 | * higher numbered CPUs in order to pack all tasks in the | |
6840 | * lowest numbered CPUs. | |
6841 | */ | |
bd939f45 | 6842 | if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu) |
532cb4c4 | 6843 | return 1; |
1af3ed3d PZ |
6844 | } |
6845 | ||
1aaf90a4 VG |
6846 | /* |
6847 | * The dst_cpu is idle and the src_cpu CPU has only 1 CFS task. | |
6848 | * It's worth migrating the task if the src_cpu's capacity is reduced | |
6849 | * because of other sched_class or IRQs if more capacity stays | |
6850 | * available on dst_cpu. | |
6851 | */ | |
6852 | if ((env->idle != CPU_NOT_IDLE) && | |
6853 | (env->src_rq->cfs.h_nr_running == 1)) { | |
6854 | if ((check_cpu_capacity(env->src_rq, sd)) && | |
6855 | (capacity_of(env->src_cpu)*sd->imbalance_pct < capacity_of(env->dst_cpu)*100)) | |
6856 | return 1; | |
6857 | } | |
6858 | ||
1af3ed3d PZ |
6859 | return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2); |
6860 | } | |
6861 | ||
969c7921 TH |
6862 | static int active_load_balance_cpu_stop(void *data); |
6863 | ||
23f0d209 JK |
6864 | static int should_we_balance(struct lb_env *env) |
6865 | { | |
6866 | struct sched_group *sg = env->sd->groups; | |
6867 | struct cpumask *sg_cpus, *sg_mask; | |
6868 | int cpu, balance_cpu = -1; | |
6869 | ||
6870 | /* | |
6871 | * In the newly idle case, we will allow all the cpu's | |
6872 | * to do the newly idle load balance. | |
6873 | */ | |
6874 | if (env->idle == CPU_NEWLY_IDLE) | |
6875 | return 1; | |
6876 | ||
6877 | sg_cpus = sched_group_cpus(sg); | |
6878 | sg_mask = sched_group_mask(sg); | |
6879 | /* Try to find first idle cpu */ | |
6880 | for_each_cpu_and(cpu, sg_cpus, env->cpus) { | |
6881 | if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu)) | |
6882 | continue; | |
6883 | ||
6884 | balance_cpu = cpu; | |
6885 | break; | |
6886 | } | |
6887 | ||
6888 | if (balance_cpu == -1) | |
6889 | balance_cpu = group_balance_cpu(sg); | |
6890 | ||
6891 | /* | |
6892 | * First idle cpu or the first cpu(busiest) in this sched group | |
6893 | * is eligible for doing load balancing at this and above domains. | |
6894 | */ | |
b0cff9d8 | 6895 | return balance_cpu == env->dst_cpu; |
23f0d209 JK |
6896 | } |
6897 | ||
1e3c88bd PZ |
6898 | /* |
6899 | * Check this_cpu to ensure it is balanced within domain. Attempt to move | |
6900 | * tasks if there is an imbalance. | |
6901 | */ | |
6902 | static int load_balance(int this_cpu, struct rq *this_rq, | |
6903 | struct sched_domain *sd, enum cpu_idle_type idle, | |
23f0d209 | 6904 | int *continue_balancing) |
1e3c88bd | 6905 | { |
88b8dac0 | 6906 | int ld_moved, cur_ld_moved, active_balance = 0; |
6263322c | 6907 | struct sched_domain *sd_parent = sd->parent; |
1e3c88bd | 6908 | struct sched_group *group; |
1e3c88bd PZ |
6909 | struct rq *busiest; |
6910 | unsigned long flags; | |
4ba29684 | 6911 | struct cpumask *cpus = this_cpu_cpumask_var_ptr(load_balance_mask); |
1e3c88bd | 6912 | |
8e45cb54 PZ |
6913 | struct lb_env env = { |
6914 | .sd = sd, | |
ddcdf6e7 PZ |
6915 | .dst_cpu = this_cpu, |
6916 | .dst_rq = this_rq, | |
88b8dac0 | 6917 | .dst_grpmask = sched_group_cpus(sd->groups), |
8e45cb54 | 6918 | .idle = idle, |
eb95308e | 6919 | .loop_break = sched_nr_migrate_break, |
b9403130 | 6920 | .cpus = cpus, |
0ec8aa00 | 6921 | .fbq_type = all, |
163122b7 | 6922 | .tasks = LIST_HEAD_INIT(env.tasks), |
8e45cb54 PZ |
6923 | }; |
6924 | ||
cfc03118 JK |
6925 | /* |
6926 | * For NEWLY_IDLE load_balancing, we don't need to consider | |
6927 | * other cpus in our group | |
6928 | */ | |
e02e60c1 | 6929 | if (idle == CPU_NEWLY_IDLE) |
cfc03118 | 6930 | env.dst_grpmask = NULL; |
cfc03118 | 6931 | |
1e3c88bd PZ |
6932 | cpumask_copy(cpus, cpu_active_mask); |
6933 | ||
1e3c88bd PZ |
6934 | schedstat_inc(sd, lb_count[idle]); |
6935 | ||
6936 | redo: | |
23f0d209 JK |
6937 | if (!should_we_balance(&env)) { |
6938 | *continue_balancing = 0; | |
1e3c88bd | 6939 | goto out_balanced; |
23f0d209 | 6940 | } |
1e3c88bd | 6941 | |
23f0d209 | 6942 | group = find_busiest_group(&env); |
1e3c88bd PZ |
6943 | if (!group) { |
6944 | schedstat_inc(sd, lb_nobusyg[idle]); | |
6945 | goto out_balanced; | |
6946 | } | |
6947 | ||
b9403130 | 6948 | busiest = find_busiest_queue(&env, group); |
1e3c88bd PZ |
6949 | if (!busiest) { |
6950 | schedstat_inc(sd, lb_nobusyq[idle]); | |
6951 | goto out_balanced; | |
6952 | } | |
6953 | ||
78feefc5 | 6954 | BUG_ON(busiest == env.dst_rq); |
1e3c88bd | 6955 | |
bd939f45 | 6956 | schedstat_add(sd, lb_imbalance[idle], env.imbalance); |
1e3c88bd | 6957 | |
1aaf90a4 VG |
6958 | env.src_cpu = busiest->cpu; |
6959 | env.src_rq = busiest; | |
6960 | ||
1e3c88bd PZ |
6961 | ld_moved = 0; |
6962 | if (busiest->nr_running > 1) { | |
6963 | /* | |
6964 | * Attempt to move tasks. If find_busiest_group has found | |
6965 | * an imbalance but busiest->nr_running <= 1, the group is | |
6966 | * still unbalanced. ld_moved simply stays zero, so it is | |
6967 | * correctly treated as an imbalance. | |
6968 | */ | |
8e45cb54 | 6969 | env.flags |= LBF_ALL_PINNED; |
c82513e5 | 6970 | env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running); |
8e45cb54 | 6971 | |
5d6523eb | 6972 | more_balance: |
163122b7 | 6973 | raw_spin_lock_irqsave(&busiest->lock, flags); |
88b8dac0 SV |
6974 | |
6975 | /* | |
6976 | * cur_ld_moved - load moved in current iteration | |
6977 | * ld_moved - cumulative load moved across iterations | |
6978 | */ | |
163122b7 | 6979 | cur_ld_moved = detach_tasks(&env); |
1e3c88bd PZ |
6980 | |
6981 | /* | |
163122b7 KT |
6982 | * We've detached some tasks from busiest_rq. Every |
6983 | * task is masked "TASK_ON_RQ_MIGRATING", so we can safely | |
6984 | * unlock busiest->lock, and we are able to be sure | |
6985 | * that nobody can manipulate the tasks in parallel. | |
6986 | * See task_rq_lock() family for the details. | |
1e3c88bd | 6987 | */ |
163122b7 KT |
6988 | |
6989 | raw_spin_unlock(&busiest->lock); | |
6990 | ||
6991 | if (cur_ld_moved) { | |
6992 | attach_tasks(&env); | |
6993 | ld_moved += cur_ld_moved; | |
6994 | } | |
6995 | ||
1e3c88bd | 6996 | local_irq_restore(flags); |
88b8dac0 | 6997 | |
f1cd0858 JK |
6998 | if (env.flags & LBF_NEED_BREAK) { |
6999 | env.flags &= ~LBF_NEED_BREAK; | |
7000 | goto more_balance; | |
7001 | } | |
7002 | ||
88b8dac0 SV |
7003 | /* |
7004 | * Revisit (affine) tasks on src_cpu that couldn't be moved to | |
7005 | * us and move them to an alternate dst_cpu in our sched_group | |
7006 | * where they can run. The upper limit on how many times we | |
7007 | * iterate on same src_cpu is dependent on number of cpus in our | |
7008 | * sched_group. | |
7009 | * | |
7010 | * This changes load balance semantics a bit on who can move | |
7011 | * load to a given_cpu. In addition to the given_cpu itself | |
7012 | * (or a ilb_cpu acting on its behalf where given_cpu is | |
7013 | * nohz-idle), we now have balance_cpu in a position to move | |
7014 | * load to given_cpu. In rare situations, this may cause | |
7015 | * conflicts (balance_cpu and given_cpu/ilb_cpu deciding | |
7016 | * _independently_ and at _same_ time to move some load to | |
7017 | * given_cpu) causing exceess load to be moved to given_cpu. | |
7018 | * This however should not happen so much in practice and | |
7019 | * moreover subsequent load balance cycles should correct the | |
7020 | * excess load moved. | |
7021 | */ | |
6263322c | 7022 | if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) { |
88b8dac0 | 7023 | |
7aff2e3a VD |
7024 | /* Prevent to re-select dst_cpu via env's cpus */ |
7025 | cpumask_clear_cpu(env.dst_cpu, env.cpus); | |
7026 | ||
78feefc5 | 7027 | env.dst_rq = cpu_rq(env.new_dst_cpu); |
88b8dac0 | 7028 | env.dst_cpu = env.new_dst_cpu; |
6263322c | 7029 | env.flags &= ~LBF_DST_PINNED; |
88b8dac0 SV |
7030 | env.loop = 0; |
7031 | env.loop_break = sched_nr_migrate_break; | |
e02e60c1 | 7032 | |
88b8dac0 SV |
7033 | /* |
7034 | * Go back to "more_balance" rather than "redo" since we | |
7035 | * need to continue with same src_cpu. | |
7036 | */ | |
7037 | goto more_balance; | |
7038 | } | |
1e3c88bd | 7039 | |
6263322c PZ |
7040 | /* |
7041 | * We failed to reach balance because of affinity. | |
7042 | */ | |
7043 | if (sd_parent) { | |
63b2ca30 | 7044 | int *group_imbalance = &sd_parent->groups->sgc->imbalance; |
6263322c | 7045 | |
afdeee05 | 7046 | if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) |
6263322c | 7047 | *group_imbalance = 1; |
6263322c PZ |
7048 | } |
7049 | ||
1e3c88bd | 7050 | /* All tasks on this runqueue were pinned by CPU affinity */ |
8e45cb54 | 7051 | if (unlikely(env.flags & LBF_ALL_PINNED)) { |
1e3c88bd | 7052 | cpumask_clear_cpu(cpu_of(busiest), cpus); |
bbf18b19 PN |
7053 | if (!cpumask_empty(cpus)) { |
7054 | env.loop = 0; | |
7055 | env.loop_break = sched_nr_migrate_break; | |
1e3c88bd | 7056 | goto redo; |
bbf18b19 | 7057 | } |
afdeee05 | 7058 | goto out_all_pinned; |
1e3c88bd PZ |
7059 | } |
7060 | } | |
7061 | ||
7062 | if (!ld_moved) { | |
7063 | schedstat_inc(sd, lb_failed[idle]); | |
58b26c4c VP |
7064 | /* |
7065 | * Increment the failure counter only on periodic balance. | |
7066 | * We do not want newidle balance, which can be very | |
7067 | * frequent, pollute the failure counter causing | |
7068 | * excessive cache_hot migrations and active balances. | |
7069 | */ | |
7070 | if (idle != CPU_NEWLY_IDLE) | |
7071 | sd->nr_balance_failed++; | |
1e3c88bd | 7072 | |
bd939f45 | 7073 | if (need_active_balance(&env)) { |
1e3c88bd PZ |
7074 | raw_spin_lock_irqsave(&busiest->lock, flags); |
7075 | ||
969c7921 TH |
7076 | /* don't kick the active_load_balance_cpu_stop, |
7077 | * if the curr task on busiest cpu can't be | |
7078 | * moved to this_cpu | |
1e3c88bd PZ |
7079 | */ |
7080 | if (!cpumask_test_cpu(this_cpu, | |
fa17b507 | 7081 | tsk_cpus_allowed(busiest->curr))) { |
1e3c88bd PZ |
7082 | raw_spin_unlock_irqrestore(&busiest->lock, |
7083 | flags); | |
8e45cb54 | 7084 | env.flags |= LBF_ALL_PINNED; |
1e3c88bd PZ |
7085 | goto out_one_pinned; |
7086 | } | |
7087 | ||
969c7921 TH |
7088 | /* |
7089 | * ->active_balance synchronizes accesses to | |
7090 | * ->active_balance_work. Once set, it's cleared | |
7091 | * only after active load balance is finished. | |
7092 | */ | |
1e3c88bd PZ |
7093 | if (!busiest->active_balance) { |
7094 | busiest->active_balance = 1; | |
7095 | busiest->push_cpu = this_cpu; | |
7096 | active_balance = 1; | |
7097 | } | |
7098 | raw_spin_unlock_irqrestore(&busiest->lock, flags); | |
969c7921 | 7099 | |
bd939f45 | 7100 | if (active_balance) { |
969c7921 TH |
7101 | stop_one_cpu_nowait(cpu_of(busiest), |
7102 | active_load_balance_cpu_stop, busiest, | |
7103 | &busiest->active_balance_work); | |
bd939f45 | 7104 | } |
1e3c88bd PZ |
7105 | |
7106 | /* | |
7107 | * We've kicked active balancing, reset the failure | |
7108 | * counter. | |
7109 | */ | |
7110 | sd->nr_balance_failed = sd->cache_nice_tries+1; | |
7111 | } | |
7112 | } else | |
7113 | sd->nr_balance_failed = 0; | |
7114 | ||
7115 | if (likely(!active_balance)) { | |
7116 | /* We were unbalanced, so reset the balancing interval */ | |
7117 | sd->balance_interval = sd->min_interval; | |
7118 | } else { | |
7119 | /* | |
7120 | * If we've begun active balancing, start to back off. This | |
7121 | * case may not be covered by the all_pinned logic if there | |
7122 | * is only 1 task on the busy runqueue (because we don't call | |
163122b7 | 7123 | * detach_tasks). |
1e3c88bd PZ |
7124 | */ |
7125 | if (sd->balance_interval < sd->max_interval) | |
7126 | sd->balance_interval *= 2; | |
7127 | } | |
7128 | ||
1e3c88bd PZ |
7129 | goto out; |
7130 | ||
7131 | out_balanced: | |
afdeee05 VG |
7132 | /* |
7133 | * We reach balance although we may have faced some affinity | |
7134 | * constraints. Clear the imbalance flag if it was set. | |
7135 | */ | |
7136 | if (sd_parent) { | |
7137 | int *group_imbalance = &sd_parent->groups->sgc->imbalance; | |
7138 | ||
7139 | if (*group_imbalance) | |
7140 | *group_imbalance = 0; | |
7141 | } | |
7142 | ||
7143 | out_all_pinned: | |
7144 | /* | |
7145 | * We reach balance because all tasks are pinned at this level so | |
7146 | * we can't migrate them. Let the imbalance flag set so parent level | |
7147 | * can try to migrate them. | |
7148 | */ | |
1e3c88bd PZ |
7149 | schedstat_inc(sd, lb_balanced[idle]); |
7150 | ||
7151 | sd->nr_balance_failed = 0; | |
7152 | ||
7153 | out_one_pinned: | |
7154 | /* tune up the balancing interval */ | |
8e45cb54 | 7155 | if (((env.flags & LBF_ALL_PINNED) && |
5b54b56b | 7156 | sd->balance_interval < MAX_PINNED_INTERVAL) || |
1e3c88bd PZ |
7157 | (sd->balance_interval < sd->max_interval)) |
7158 | sd->balance_interval *= 2; | |
7159 | ||
46e49b38 | 7160 | ld_moved = 0; |
1e3c88bd | 7161 | out: |
1e3c88bd PZ |
7162 | return ld_moved; |
7163 | } | |
7164 | ||
52a08ef1 JL |
7165 | static inline unsigned long |
7166 | get_sd_balance_interval(struct sched_domain *sd, int cpu_busy) | |
7167 | { | |
7168 | unsigned long interval = sd->balance_interval; | |
7169 | ||
7170 | if (cpu_busy) | |
7171 | interval *= sd->busy_factor; | |
7172 | ||
7173 | /* scale ms to jiffies */ | |
7174 | interval = msecs_to_jiffies(interval); | |
7175 | interval = clamp(interval, 1UL, max_load_balance_interval); | |
7176 | ||
7177 | return interval; | |
7178 | } | |
7179 | ||
7180 | static inline void | |
7181 | update_next_balance(struct sched_domain *sd, int cpu_busy, unsigned long *next_balance) | |
7182 | { | |
7183 | unsigned long interval, next; | |
7184 | ||
7185 | interval = get_sd_balance_interval(sd, cpu_busy); | |
7186 | next = sd->last_balance + interval; | |
7187 | ||
7188 | if (time_after(*next_balance, next)) | |
7189 | *next_balance = next; | |
7190 | } | |
7191 | ||
1e3c88bd PZ |
7192 | /* |
7193 | * idle_balance is called by schedule() if this_cpu is about to become | |
7194 | * idle. Attempts to pull tasks from other CPUs. | |
7195 | */ | |
6e83125c | 7196 | static int idle_balance(struct rq *this_rq) |
1e3c88bd | 7197 | { |
52a08ef1 JL |
7198 | unsigned long next_balance = jiffies + HZ; |
7199 | int this_cpu = this_rq->cpu; | |
1e3c88bd PZ |
7200 | struct sched_domain *sd; |
7201 | int pulled_task = 0; | |
9bd721c5 | 7202 | u64 curr_cost = 0; |
1e3c88bd | 7203 | |
6e83125c | 7204 | idle_enter_fair(this_rq); |
0e5b5337 | 7205 | |
6e83125c PZ |
7206 | /* |
7207 | * We must set idle_stamp _before_ calling idle_balance(), such that we | |
7208 | * measure the duration of idle_balance() as idle time. | |
7209 | */ | |
7210 | this_rq->idle_stamp = rq_clock(this_rq); | |
7211 | ||
4486edd1 TC |
7212 | if (this_rq->avg_idle < sysctl_sched_migration_cost || |
7213 | !this_rq->rd->overload) { | |
52a08ef1 JL |
7214 | rcu_read_lock(); |
7215 | sd = rcu_dereference_check_sched_domain(this_rq->sd); | |
7216 | if (sd) | |
7217 | update_next_balance(sd, 0, &next_balance); | |
7218 | rcu_read_unlock(); | |
7219 | ||
6e83125c | 7220 | goto out; |
52a08ef1 | 7221 | } |
1e3c88bd | 7222 | |
f492e12e PZ |
7223 | /* |
7224 | * Drop the rq->lock, but keep IRQ/preempt disabled. | |
7225 | */ | |
7226 | raw_spin_unlock(&this_rq->lock); | |
7227 | ||
48a16753 | 7228 | update_blocked_averages(this_cpu); |
dce840a0 | 7229 | rcu_read_lock(); |
1e3c88bd | 7230 | for_each_domain(this_cpu, sd) { |
23f0d209 | 7231 | int continue_balancing = 1; |
9bd721c5 | 7232 | u64 t0, domain_cost; |
1e3c88bd PZ |
7233 | |
7234 | if (!(sd->flags & SD_LOAD_BALANCE)) | |
7235 | continue; | |
7236 | ||
52a08ef1 JL |
7237 | if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) { |
7238 | update_next_balance(sd, 0, &next_balance); | |
9bd721c5 | 7239 | break; |
52a08ef1 | 7240 | } |
9bd721c5 | 7241 | |
f492e12e | 7242 | if (sd->flags & SD_BALANCE_NEWIDLE) { |
9bd721c5 JL |
7243 | t0 = sched_clock_cpu(this_cpu); |
7244 | ||
f492e12e | 7245 | pulled_task = load_balance(this_cpu, this_rq, |
23f0d209 JK |
7246 | sd, CPU_NEWLY_IDLE, |
7247 | &continue_balancing); | |
9bd721c5 JL |
7248 | |
7249 | domain_cost = sched_clock_cpu(this_cpu) - t0; | |
7250 | if (domain_cost > sd->max_newidle_lb_cost) | |
7251 | sd->max_newidle_lb_cost = domain_cost; | |
7252 | ||
7253 | curr_cost += domain_cost; | |
f492e12e | 7254 | } |
1e3c88bd | 7255 | |
52a08ef1 | 7256 | update_next_balance(sd, 0, &next_balance); |
39a4d9ca JL |
7257 | |
7258 | /* | |
7259 | * Stop searching for tasks to pull if there are | |
7260 | * now runnable tasks on this rq. | |
7261 | */ | |
7262 | if (pulled_task || this_rq->nr_running > 0) | |
1e3c88bd | 7263 | break; |
1e3c88bd | 7264 | } |
dce840a0 | 7265 | rcu_read_unlock(); |
f492e12e PZ |
7266 | |
7267 | raw_spin_lock(&this_rq->lock); | |
7268 | ||
0e5b5337 JL |
7269 | if (curr_cost > this_rq->max_idle_balance_cost) |
7270 | this_rq->max_idle_balance_cost = curr_cost; | |
7271 | ||
e5fc6611 | 7272 | /* |
0e5b5337 JL |
7273 | * While browsing the domains, we released the rq lock, a task could |
7274 | * have been enqueued in the meantime. Since we're not going idle, | |
7275 | * pretend we pulled a task. | |
e5fc6611 | 7276 | */ |
0e5b5337 | 7277 | if (this_rq->cfs.h_nr_running && !pulled_task) |
6e83125c | 7278 | pulled_task = 1; |
e5fc6611 | 7279 | |
52a08ef1 JL |
7280 | out: |
7281 | /* Move the next balance forward */ | |
7282 | if (time_after(this_rq->next_balance, next_balance)) | |
1e3c88bd | 7283 | this_rq->next_balance = next_balance; |
9bd721c5 | 7284 | |
e4aa358b | 7285 | /* Is there a task of a high priority class? */ |
46383648 | 7286 | if (this_rq->nr_running != this_rq->cfs.h_nr_running) |
e4aa358b KT |
7287 | pulled_task = -1; |
7288 | ||
7289 | if (pulled_task) { | |
7290 | idle_exit_fair(this_rq); | |
6e83125c | 7291 | this_rq->idle_stamp = 0; |
e4aa358b | 7292 | } |
6e83125c | 7293 | |
3c4017c1 | 7294 | return pulled_task; |
1e3c88bd PZ |
7295 | } |
7296 | ||
7297 | /* | |
969c7921 TH |
7298 | * active_load_balance_cpu_stop is run by cpu stopper. It pushes |
7299 | * running tasks off the busiest CPU onto idle CPUs. It requires at | |
7300 | * least 1 task to be running on each physical CPU where possible, and | |
7301 | * avoids physical / logical imbalances. | |
1e3c88bd | 7302 | */ |
969c7921 | 7303 | static int active_load_balance_cpu_stop(void *data) |
1e3c88bd | 7304 | { |
969c7921 TH |
7305 | struct rq *busiest_rq = data; |
7306 | int busiest_cpu = cpu_of(busiest_rq); | |
1e3c88bd | 7307 | int target_cpu = busiest_rq->push_cpu; |
969c7921 | 7308 | struct rq *target_rq = cpu_rq(target_cpu); |
1e3c88bd | 7309 | struct sched_domain *sd; |
e5673f28 | 7310 | struct task_struct *p = NULL; |
969c7921 TH |
7311 | |
7312 | raw_spin_lock_irq(&busiest_rq->lock); | |
7313 | ||
7314 | /* make sure the requested cpu hasn't gone down in the meantime */ | |
7315 | if (unlikely(busiest_cpu != smp_processor_id() || | |
7316 | !busiest_rq->active_balance)) | |
7317 | goto out_unlock; | |
1e3c88bd PZ |
7318 | |
7319 | /* Is there any task to move? */ | |
7320 | if (busiest_rq->nr_running <= 1) | |
969c7921 | 7321 | goto out_unlock; |
1e3c88bd PZ |
7322 | |
7323 | /* | |
7324 | * This condition is "impossible", if it occurs | |
7325 | * we need to fix it. Originally reported by | |
7326 | * Bjorn Helgaas on a 128-cpu setup. | |
7327 | */ | |
7328 | BUG_ON(busiest_rq == target_rq); | |
7329 | ||
1e3c88bd | 7330 | /* Search for an sd spanning us and the target CPU. */ |
dce840a0 | 7331 | rcu_read_lock(); |
1e3c88bd PZ |
7332 | for_each_domain(target_cpu, sd) { |
7333 | if ((sd->flags & SD_LOAD_BALANCE) && | |
7334 | cpumask_test_cpu(busiest_cpu, sched_domain_span(sd))) | |
7335 | break; | |
7336 | } | |
7337 | ||
7338 | if (likely(sd)) { | |
8e45cb54 PZ |
7339 | struct lb_env env = { |
7340 | .sd = sd, | |
ddcdf6e7 PZ |
7341 | .dst_cpu = target_cpu, |
7342 | .dst_rq = target_rq, | |
7343 | .src_cpu = busiest_rq->cpu, | |
7344 | .src_rq = busiest_rq, | |
8e45cb54 PZ |
7345 | .idle = CPU_IDLE, |
7346 | }; | |
7347 | ||
1e3c88bd PZ |
7348 | schedstat_inc(sd, alb_count); |
7349 | ||
e5673f28 KT |
7350 | p = detach_one_task(&env); |
7351 | if (p) | |
1e3c88bd PZ |
7352 | schedstat_inc(sd, alb_pushed); |
7353 | else | |
7354 | schedstat_inc(sd, alb_failed); | |
7355 | } | |
dce840a0 | 7356 | rcu_read_unlock(); |
969c7921 TH |
7357 | out_unlock: |
7358 | busiest_rq->active_balance = 0; | |
e5673f28 KT |
7359 | raw_spin_unlock(&busiest_rq->lock); |
7360 | ||
7361 | if (p) | |
7362 | attach_one_task(target_rq, p); | |
7363 | ||
7364 | local_irq_enable(); | |
7365 | ||
969c7921 | 7366 | return 0; |
1e3c88bd PZ |
7367 | } |
7368 | ||
d987fc7f MG |
7369 | static inline int on_null_domain(struct rq *rq) |
7370 | { | |
7371 | return unlikely(!rcu_dereference_sched(rq->sd)); | |
7372 | } | |
7373 | ||
3451d024 | 7374 | #ifdef CONFIG_NO_HZ_COMMON |
83cd4fe2 VP |
7375 | /* |
7376 | * idle load balancing details | |
83cd4fe2 VP |
7377 | * - When one of the busy CPUs notice that there may be an idle rebalancing |
7378 | * needed, they will kick the idle load balancer, which then does idle | |
7379 | * load balancing for all the idle CPUs. | |
7380 | */ | |
1e3c88bd | 7381 | static struct { |
83cd4fe2 | 7382 | cpumask_var_t idle_cpus_mask; |
0b005cf5 | 7383 | atomic_t nr_cpus; |
83cd4fe2 VP |
7384 | unsigned long next_balance; /* in jiffy units */ |
7385 | } nohz ____cacheline_aligned; | |
1e3c88bd | 7386 | |
3dd0337d | 7387 | static inline int find_new_ilb(void) |
1e3c88bd | 7388 | { |
0b005cf5 | 7389 | int ilb = cpumask_first(nohz.idle_cpus_mask); |
1e3c88bd | 7390 | |
786d6dc7 SS |
7391 | if (ilb < nr_cpu_ids && idle_cpu(ilb)) |
7392 | return ilb; | |
7393 | ||
7394 | return nr_cpu_ids; | |
1e3c88bd | 7395 | } |
1e3c88bd | 7396 | |
83cd4fe2 VP |
7397 | /* |
7398 | * Kick a CPU to do the nohz balancing, if it is time for it. We pick the | |
7399 | * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle | |
7400 | * CPU (if there is one). | |
7401 | */ | |
0aeeeeba | 7402 | static void nohz_balancer_kick(void) |
83cd4fe2 VP |
7403 | { |
7404 | int ilb_cpu; | |
7405 | ||
7406 | nohz.next_balance++; | |
7407 | ||
3dd0337d | 7408 | ilb_cpu = find_new_ilb(); |
83cd4fe2 | 7409 | |
0b005cf5 SS |
7410 | if (ilb_cpu >= nr_cpu_ids) |
7411 | return; | |
83cd4fe2 | 7412 | |
cd490c5b | 7413 | if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu))) |
1c792db7 SS |
7414 | return; |
7415 | /* | |
7416 | * Use smp_send_reschedule() instead of resched_cpu(). | |
7417 | * This way we generate a sched IPI on the target cpu which | |
7418 | * is idle. And the softirq performing nohz idle load balance | |
7419 | * will be run before returning from the IPI. | |
7420 | */ | |
7421 | smp_send_reschedule(ilb_cpu); | |
83cd4fe2 VP |
7422 | return; |
7423 | } | |
7424 | ||
c1cc017c | 7425 | static inline void nohz_balance_exit_idle(int cpu) |
71325960 SS |
7426 | { |
7427 | if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) { | |
d987fc7f MG |
7428 | /* |
7429 | * Completely isolated CPUs don't ever set, so we must test. | |
7430 | */ | |
7431 | if (likely(cpumask_test_cpu(cpu, nohz.idle_cpus_mask))) { | |
7432 | cpumask_clear_cpu(cpu, nohz.idle_cpus_mask); | |
7433 | atomic_dec(&nohz.nr_cpus); | |
7434 | } | |
71325960 SS |
7435 | clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); |
7436 | } | |
7437 | } | |
7438 | ||
69e1e811 SS |
7439 | static inline void set_cpu_sd_state_busy(void) |
7440 | { | |
7441 | struct sched_domain *sd; | |
37dc6b50 | 7442 | int cpu = smp_processor_id(); |
69e1e811 | 7443 | |
69e1e811 | 7444 | rcu_read_lock(); |
37dc6b50 | 7445 | sd = rcu_dereference(per_cpu(sd_busy, cpu)); |
25f55d9d VG |
7446 | |
7447 | if (!sd || !sd->nohz_idle) | |
7448 | goto unlock; | |
7449 | sd->nohz_idle = 0; | |
7450 | ||
63b2ca30 | 7451 | atomic_inc(&sd->groups->sgc->nr_busy_cpus); |
25f55d9d | 7452 | unlock: |
69e1e811 SS |
7453 | rcu_read_unlock(); |
7454 | } | |
7455 | ||
7456 | void set_cpu_sd_state_idle(void) | |
7457 | { | |
7458 | struct sched_domain *sd; | |
37dc6b50 | 7459 | int cpu = smp_processor_id(); |
69e1e811 | 7460 | |
69e1e811 | 7461 | rcu_read_lock(); |
37dc6b50 | 7462 | sd = rcu_dereference(per_cpu(sd_busy, cpu)); |
25f55d9d VG |
7463 | |
7464 | if (!sd || sd->nohz_idle) | |
7465 | goto unlock; | |
7466 | sd->nohz_idle = 1; | |
7467 | ||
63b2ca30 | 7468 | atomic_dec(&sd->groups->sgc->nr_busy_cpus); |
25f55d9d | 7469 | unlock: |
69e1e811 SS |
7470 | rcu_read_unlock(); |
7471 | } | |
7472 | ||
1e3c88bd | 7473 | /* |
c1cc017c | 7474 | * This routine will record that the cpu is going idle with tick stopped. |
0b005cf5 | 7475 | * This info will be used in performing idle load balancing in the future. |
1e3c88bd | 7476 | */ |
c1cc017c | 7477 | void nohz_balance_enter_idle(int cpu) |
1e3c88bd | 7478 | { |
71325960 SS |
7479 | /* |
7480 | * If this cpu is going down, then nothing needs to be done. | |
7481 | */ | |
7482 | if (!cpu_active(cpu)) | |
7483 | return; | |
7484 | ||
c1cc017c AS |
7485 | if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu))) |
7486 | return; | |
1e3c88bd | 7487 | |
d987fc7f MG |
7488 | /* |
7489 | * If we're a completely isolated CPU, we don't play. | |
7490 | */ | |
7491 | if (on_null_domain(cpu_rq(cpu))) | |
7492 | return; | |
7493 | ||
c1cc017c AS |
7494 | cpumask_set_cpu(cpu, nohz.idle_cpus_mask); |
7495 | atomic_inc(&nohz.nr_cpus); | |
7496 | set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); | |
1e3c88bd | 7497 | } |
71325960 | 7498 | |
0db0628d | 7499 | static int sched_ilb_notifier(struct notifier_block *nfb, |
71325960 SS |
7500 | unsigned long action, void *hcpu) |
7501 | { | |
7502 | switch (action & ~CPU_TASKS_FROZEN) { | |
7503 | case CPU_DYING: | |
c1cc017c | 7504 | nohz_balance_exit_idle(smp_processor_id()); |
71325960 SS |
7505 | return NOTIFY_OK; |
7506 | default: | |
7507 | return NOTIFY_DONE; | |
7508 | } | |
7509 | } | |
1e3c88bd PZ |
7510 | #endif |
7511 | ||
7512 | static DEFINE_SPINLOCK(balancing); | |
7513 | ||
49c022e6 PZ |
7514 | /* |
7515 | * Scale the max load_balance interval with the number of CPUs in the system. | |
7516 | * This trades load-balance latency on larger machines for less cross talk. | |
7517 | */ | |
029632fb | 7518 | void update_max_interval(void) |
49c022e6 PZ |
7519 | { |
7520 | max_load_balance_interval = HZ*num_online_cpus()/10; | |
7521 | } | |
7522 | ||
1e3c88bd PZ |
7523 | /* |
7524 | * It checks each scheduling domain to see if it is due to be balanced, | |
7525 | * and initiates a balancing operation if so. | |
7526 | * | |
b9b0853a | 7527 | * Balancing parameters are set up in init_sched_domains. |
1e3c88bd | 7528 | */ |
f7ed0a89 | 7529 | static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) |
1e3c88bd | 7530 | { |
23f0d209 | 7531 | int continue_balancing = 1; |
f7ed0a89 | 7532 | int cpu = rq->cpu; |
1e3c88bd | 7533 | unsigned long interval; |
04f733b4 | 7534 | struct sched_domain *sd; |
1e3c88bd PZ |
7535 | /* Earliest time when we have to do rebalance again */ |
7536 | unsigned long next_balance = jiffies + 60*HZ; | |
7537 | int update_next_balance = 0; | |
f48627e6 JL |
7538 | int need_serialize, need_decay = 0; |
7539 | u64 max_cost = 0; | |
1e3c88bd | 7540 | |
48a16753 | 7541 | update_blocked_averages(cpu); |
2069dd75 | 7542 | |
dce840a0 | 7543 | rcu_read_lock(); |
1e3c88bd | 7544 | for_each_domain(cpu, sd) { |
f48627e6 JL |
7545 | /* |
7546 | * Decay the newidle max times here because this is a regular | |
7547 | * visit to all the domains. Decay ~1% per second. | |
7548 | */ | |
7549 | if (time_after(jiffies, sd->next_decay_max_lb_cost)) { | |
7550 | sd->max_newidle_lb_cost = | |
7551 | (sd->max_newidle_lb_cost * 253) / 256; | |
7552 | sd->next_decay_max_lb_cost = jiffies + HZ; | |
7553 | need_decay = 1; | |
7554 | } | |
7555 | max_cost += sd->max_newidle_lb_cost; | |
7556 | ||
1e3c88bd PZ |
7557 | if (!(sd->flags & SD_LOAD_BALANCE)) |
7558 | continue; | |
7559 | ||
f48627e6 JL |
7560 | /* |
7561 | * Stop the load balance at this level. There is another | |
7562 | * CPU in our sched group which is doing load balancing more | |
7563 | * actively. | |
7564 | */ | |
7565 | if (!continue_balancing) { | |
7566 | if (need_decay) | |
7567 | continue; | |
7568 | break; | |
7569 | } | |
7570 | ||
52a08ef1 | 7571 | interval = get_sd_balance_interval(sd, idle != CPU_IDLE); |
1e3c88bd PZ |
7572 | |
7573 | need_serialize = sd->flags & SD_SERIALIZE; | |
1e3c88bd PZ |
7574 | if (need_serialize) { |
7575 | if (!spin_trylock(&balancing)) | |
7576 | goto out; | |
7577 | } | |
7578 | ||
7579 | if (time_after_eq(jiffies, sd->last_balance + interval)) { | |
23f0d209 | 7580 | if (load_balance(cpu, rq, sd, idle, &continue_balancing)) { |
1e3c88bd | 7581 | /* |
6263322c | 7582 | * The LBF_DST_PINNED logic could have changed |
de5eb2dd JK |
7583 | * env->dst_cpu, so we can't know our idle |
7584 | * state even if we migrated tasks. Update it. | |
1e3c88bd | 7585 | */ |
de5eb2dd | 7586 | idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE; |
1e3c88bd PZ |
7587 | } |
7588 | sd->last_balance = jiffies; | |
52a08ef1 | 7589 | interval = get_sd_balance_interval(sd, idle != CPU_IDLE); |
1e3c88bd PZ |
7590 | } |
7591 | if (need_serialize) | |
7592 | spin_unlock(&balancing); | |
7593 | out: | |
7594 | if (time_after(next_balance, sd->last_balance + interval)) { | |
7595 | next_balance = sd->last_balance + interval; | |
7596 | update_next_balance = 1; | |
7597 | } | |
f48627e6 JL |
7598 | } |
7599 | if (need_decay) { | |
1e3c88bd | 7600 | /* |
f48627e6 JL |
7601 | * Ensure the rq-wide value also decays but keep it at a |
7602 | * reasonable floor to avoid funnies with rq->avg_idle. | |
1e3c88bd | 7603 | */ |
f48627e6 JL |
7604 | rq->max_idle_balance_cost = |
7605 | max((u64)sysctl_sched_migration_cost, max_cost); | |
1e3c88bd | 7606 | } |
dce840a0 | 7607 | rcu_read_unlock(); |
1e3c88bd PZ |
7608 | |
7609 | /* | |
7610 | * next_balance will be updated only when there is a need. | |
7611 | * When the cpu is attached to null domain for ex, it will not be | |
7612 | * updated. | |
7613 | */ | |
7614 | if (likely(update_next_balance)) | |
7615 | rq->next_balance = next_balance; | |
7616 | } | |
7617 | ||
3451d024 | 7618 | #ifdef CONFIG_NO_HZ_COMMON |
1e3c88bd | 7619 | /* |
3451d024 | 7620 | * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the |
1e3c88bd PZ |
7621 | * rebalancing for all the cpus for whom scheduler ticks are stopped. |
7622 | */ | |
208cb16b | 7623 | static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) |
83cd4fe2 | 7624 | { |
208cb16b | 7625 | int this_cpu = this_rq->cpu; |
83cd4fe2 VP |
7626 | struct rq *rq; |
7627 | int balance_cpu; | |
7628 | ||
1c792db7 SS |
7629 | if (idle != CPU_IDLE || |
7630 | !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu))) | |
7631 | goto end; | |
83cd4fe2 VP |
7632 | |
7633 | for_each_cpu(balance_cpu, nohz.idle_cpus_mask) { | |
8a6d42d1 | 7634 | if (balance_cpu == this_cpu || !idle_cpu(balance_cpu)) |
83cd4fe2 VP |
7635 | continue; |
7636 | ||
7637 | /* | |
7638 | * If this cpu gets work to do, stop the load balancing | |
7639 | * work being done for other cpus. Next load | |
7640 | * balancing owner will pick it up. | |
7641 | */ | |
1c792db7 | 7642 | if (need_resched()) |
83cd4fe2 | 7643 | break; |
83cd4fe2 | 7644 | |
5ed4f1d9 VG |
7645 | rq = cpu_rq(balance_cpu); |
7646 | ||
ed61bbc6 TC |
7647 | /* |
7648 | * If time for next balance is due, | |
7649 | * do the balance. | |
7650 | */ | |
7651 | if (time_after_eq(jiffies, rq->next_balance)) { | |
7652 | raw_spin_lock_irq(&rq->lock); | |
7653 | update_rq_clock(rq); | |
7654 | update_idle_cpu_load(rq); | |
7655 | raw_spin_unlock_irq(&rq->lock); | |
7656 | rebalance_domains(rq, CPU_IDLE); | |
7657 | } | |
83cd4fe2 | 7658 | |
83cd4fe2 VP |
7659 | if (time_after(this_rq->next_balance, rq->next_balance)) |
7660 | this_rq->next_balance = rq->next_balance; | |
7661 | } | |
7662 | nohz.next_balance = this_rq->next_balance; | |
1c792db7 SS |
7663 | end: |
7664 | clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)); | |
83cd4fe2 VP |
7665 | } |
7666 | ||
7667 | /* | |
0b005cf5 | 7668 | * Current heuristic for kicking the idle load balancer in the presence |
1aaf90a4 | 7669 | * of an idle cpu in the system. |
0b005cf5 | 7670 | * - This rq has more than one task. |
1aaf90a4 VG |
7671 | * - This rq has at least one CFS task and the capacity of the CPU is |
7672 | * significantly reduced because of RT tasks or IRQs. | |
7673 | * - At parent of LLC scheduler domain level, this cpu's scheduler group has | |
7674 | * multiple busy cpu. | |
0b005cf5 SS |
7675 | * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler |
7676 | * domain span are idle. | |
83cd4fe2 | 7677 | */ |
1aaf90a4 | 7678 | static inline bool nohz_kick_needed(struct rq *rq) |
83cd4fe2 VP |
7679 | { |
7680 | unsigned long now = jiffies; | |
0b005cf5 | 7681 | struct sched_domain *sd; |
63b2ca30 | 7682 | struct sched_group_capacity *sgc; |
4a725627 | 7683 | int nr_busy, cpu = rq->cpu; |
1aaf90a4 | 7684 | bool kick = false; |
83cd4fe2 | 7685 | |
4a725627 | 7686 | if (unlikely(rq->idle_balance)) |
1aaf90a4 | 7687 | return false; |
83cd4fe2 | 7688 | |
1c792db7 SS |
7689 | /* |
7690 | * We may be recently in ticked or tickless idle mode. At the first | |
7691 | * busy tick after returning from idle, we will update the busy stats. | |
7692 | */ | |
69e1e811 | 7693 | set_cpu_sd_state_busy(); |
c1cc017c | 7694 | nohz_balance_exit_idle(cpu); |
0b005cf5 SS |
7695 | |
7696 | /* | |
7697 | * None are in tickless mode and hence no need for NOHZ idle load | |
7698 | * balancing. | |
7699 | */ | |
7700 | if (likely(!atomic_read(&nohz.nr_cpus))) | |
1aaf90a4 | 7701 | return false; |
1c792db7 SS |
7702 | |
7703 | if (time_before(now, nohz.next_balance)) | |
1aaf90a4 | 7704 | return false; |
83cd4fe2 | 7705 | |
0b005cf5 | 7706 | if (rq->nr_running >= 2) |
1aaf90a4 | 7707 | return true; |
83cd4fe2 | 7708 | |
067491b7 | 7709 | rcu_read_lock(); |
37dc6b50 | 7710 | sd = rcu_dereference(per_cpu(sd_busy, cpu)); |
37dc6b50 | 7711 | if (sd) { |
63b2ca30 NP |
7712 | sgc = sd->groups->sgc; |
7713 | nr_busy = atomic_read(&sgc->nr_busy_cpus); | |
0b005cf5 | 7714 | |
1aaf90a4 VG |
7715 | if (nr_busy > 1) { |
7716 | kick = true; | |
7717 | goto unlock; | |
7718 | } | |
7719 | ||
83cd4fe2 | 7720 | } |
37dc6b50 | 7721 | |
1aaf90a4 VG |
7722 | sd = rcu_dereference(rq->sd); |
7723 | if (sd) { | |
7724 | if ((rq->cfs.h_nr_running >= 1) && | |
7725 | check_cpu_capacity(rq, sd)) { | |
7726 | kick = true; | |
7727 | goto unlock; | |
7728 | } | |
7729 | } | |
37dc6b50 | 7730 | |
1aaf90a4 | 7731 | sd = rcu_dereference(per_cpu(sd_asym, cpu)); |
37dc6b50 | 7732 | if (sd && (cpumask_first_and(nohz.idle_cpus_mask, |
1aaf90a4 VG |
7733 | sched_domain_span(sd)) < cpu)) { |
7734 | kick = true; | |
7735 | goto unlock; | |
7736 | } | |
067491b7 | 7737 | |
1aaf90a4 | 7738 | unlock: |
067491b7 | 7739 | rcu_read_unlock(); |
1aaf90a4 | 7740 | return kick; |
83cd4fe2 VP |
7741 | } |
7742 | #else | |
208cb16b | 7743 | static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { } |
83cd4fe2 VP |
7744 | #endif |
7745 | ||
7746 | /* | |
7747 | * run_rebalance_domains is triggered when needed from the scheduler tick. | |
7748 | * Also triggered for nohz idle balancing (with nohz_balancing_kick set). | |
7749 | */ | |
1e3c88bd PZ |
7750 | static void run_rebalance_domains(struct softirq_action *h) |
7751 | { | |
208cb16b | 7752 | struct rq *this_rq = this_rq(); |
6eb57e0d | 7753 | enum cpu_idle_type idle = this_rq->idle_balance ? |
1e3c88bd PZ |
7754 | CPU_IDLE : CPU_NOT_IDLE; |
7755 | ||
f7ed0a89 | 7756 | rebalance_domains(this_rq, idle); |
1e3c88bd | 7757 | |
1e3c88bd | 7758 | /* |
83cd4fe2 | 7759 | * If this cpu has a pending nohz_balance_kick, then do the |
1e3c88bd PZ |
7760 | * balancing on behalf of the other idle cpus whose ticks are |
7761 | * stopped. | |
7762 | */ | |
208cb16b | 7763 | nohz_idle_balance(this_rq, idle); |
1e3c88bd PZ |
7764 | } |
7765 | ||
1e3c88bd PZ |
7766 | /* |
7767 | * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing. | |
1e3c88bd | 7768 | */ |
7caff66f | 7769 | void trigger_load_balance(struct rq *rq) |
1e3c88bd | 7770 | { |
1e3c88bd | 7771 | /* Don't need to rebalance while attached to NULL domain */ |
c726099e DL |
7772 | if (unlikely(on_null_domain(rq))) |
7773 | return; | |
7774 | ||
7775 | if (time_after_eq(jiffies, rq->next_balance)) | |
1e3c88bd | 7776 | raise_softirq(SCHED_SOFTIRQ); |
3451d024 | 7777 | #ifdef CONFIG_NO_HZ_COMMON |
c726099e | 7778 | if (nohz_kick_needed(rq)) |
0aeeeeba | 7779 | nohz_balancer_kick(); |
83cd4fe2 | 7780 | #endif |
1e3c88bd PZ |
7781 | } |
7782 | ||
0bcdcf28 CE |
7783 | static void rq_online_fair(struct rq *rq) |
7784 | { | |
7785 | update_sysctl(); | |
0e59bdae KT |
7786 | |
7787 | update_runtime_enabled(rq); | |
0bcdcf28 CE |
7788 | } |
7789 | ||
7790 | static void rq_offline_fair(struct rq *rq) | |
7791 | { | |
7792 | update_sysctl(); | |
a4c96ae3 PB |
7793 | |
7794 | /* Ensure any throttled groups are reachable by pick_next_task */ | |
7795 | unthrottle_offline_cfs_rqs(rq); | |
0bcdcf28 CE |
7796 | } |
7797 | ||
55e12e5e | 7798 | #endif /* CONFIG_SMP */ |
e1d1484f | 7799 | |
bf0f6f24 IM |
7800 | /* |
7801 | * scheduler tick hitting a task of our scheduling class: | |
7802 | */ | |
8f4d37ec | 7803 | static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) |
bf0f6f24 IM |
7804 | { |
7805 | struct cfs_rq *cfs_rq; | |
7806 | struct sched_entity *se = &curr->se; | |
7807 | ||
7808 | for_each_sched_entity(se) { | |
7809 | cfs_rq = cfs_rq_of(se); | |
8f4d37ec | 7810 | entity_tick(cfs_rq, se, queued); |
bf0f6f24 | 7811 | } |
18bf2805 | 7812 | |
10e84b97 | 7813 | if (numabalancing_enabled) |
cbee9f88 | 7814 | task_tick_numa(rq, curr); |
3d59eebc | 7815 | |
18bf2805 | 7816 | update_rq_runnable_avg(rq, 1); |
bf0f6f24 IM |
7817 | } |
7818 | ||
7819 | /* | |
cd29fe6f PZ |
7820 | * called on fork with the child task as argument from the parent's context |
7821 | * - child not yet on the tasklist | |
7822 | * - preemption disabled | |
bf0f6f24 | 7823 | */ |
cd29fe6f | 7824 | static void task_fork_fair(struct task_struct *p) |
bf0f6f24 | 7825 | { |
4fc420c9 DN |
7826 | struct cfs_rq *cfs_rq; |
7827 | struct sched_entity *se = &p->se, *curr; | |
00bf7bfc | 7828 | int this_cpu = smp_processor_id(); |
cd29fe6f PZ |
7829 | struct rq *rq = this_rq(); |
7830 | unsigned long flags; | |
7831 | ||
05fa785c | 7832 | raw_spin_lock_irqsave(&rq->lock, flags); |
bf0f6f24 | 7833 | |
861d034e PZ |
7834 | update_rq_clock(rq); |
7835 | ||
4fc420c9 DN |
7836 | cfs_rq = task_cfs_rq(current); |
7837 | curr = cfs_rq->curr; | |
7838 | ||
6c9a27f5 DN |
7839 | /* |
7840 | * Not only the cpu but also the task_group of the parent might have | |
7841 | * been changed after parent->se.parent,cfs_rq were copied to | |
7842 | * child->se.parent,cfs_rq. So call __set_task_cpu() to make those | |
7843 | * of child point to valid ones. | |
7844 | */ | |
7845 | rcu_read_lock(); | |
7846 | __set_task_cpu(p, this_cpu); | |
7847 | rcu_read_unlock(); | |
bf0f6f24 | 7848 | |
7109c442 | 7849 | update_curr(cfs_rq); |
cd29fe6f | 7850 | |
b5d9d734 MG |
7851 | if (curr) |
7852 | se->vruntime = curr->vruntime; | |
aeb73b04 | 7853 | place_entity(cfs_rq, se, 1); |
4d78e7b6 | 7854 | |
cd29fe6f | 7855 | if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) { |
87fefa38 | 7856 | /* |
edcb60a3 IM |
7857 | * Upon rescheduling, sched_class::put_prev_task() will place |
7858 | * 'current' within the tree based on its new key value. | |
7859 | */ | |
4d78e7b6 | 7860 | swap(curr->vruntime, se->vruntime); |
8875125e | 7861 | resched_curr(rq); |
4d78e7b6 | 7862 | } |
bf0f6f24 | 7863 | |
88ec22d3 PZ |
7864 | se->vruntime -= cfs_rq->min_vruntime; |
7865 | ||
05fa785c | 7866 | raw_spin_unlock_irqrestore(&rq->lock, flags); |
bf0f6f24 IM |
7867 | } |
7868 | ||
cb469845 SR |
7869 | /* |
7870 | * Priority of the task has changed. Check to see if we preempt | |
7871 | * the current task. | |
7872 | */ | |
da7a735e PZ |
7873 | static void |
7874 | prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio) | |
cb469845 | 7875 | { |
da0c1e65 | 7876 | if (!task_on_rq_queued(p)) |
da7a735e PZ |
7877 | return; |
7878 | ||
cb469845 SR |
7879 | /* |
7880 | * Reschedule if we are currently running on this runqueue and | |
7881 | * our priority decreased, or if we are not currently running on | |
7882 | * this runqueue and our priority is higher than the current's | |
7883 | */ | |
da7a735e | 7884 | if (rq->curr == p) { |
cb469845 | 7885 | if (p->prio > oldprio) |
8875125e | 7886 | resched_curr(rq); |
cb469845 | 7887 | } else |
15afe09b | 7888 | check_preempt_curr(rq, p, 0); |
cb469845 SR |
7889 | } |
7890 | ||
da7a735e PZ |
7891 | static void switched_from_fair(struct rq *rq, struct task_struct *p) |
7892 | { | |
7893 | struct sched_entity *se = &p->se; | |
7894 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
7895 | ||
7896 | /* | |
791c9e02 | 7897 | * Ensure the task's vruntime is normalized, so that when it's |
da7a735e PZ |
7898 | * switched back to the fair class the enqueue_entity(.flags=0) will |
7899 | * do the right thing. | |
7900 | * | |
da0c1e65 KT |
7901 | * If it's queued, then the dequeue_entity(.flags=0) will already |
7902 | * have normalized the vruntime, if it's !queued, then only when | |
da7a735e PZ |
7903 | * the task is sleeping will it still have non-normalized vruntime. |
7904 | */ | |
da0c1e65 | 7905 | if (!task_on_rq_queued(p) && p->state != TASK_RUNNING) { |
da7a735e PZ |
7906 | /* |
7907 | * Fix up our vruntime so that the current sleep doesn't | |
7908 | * cause 'unlimited' sleep bonus. | |
7909 | */ | |
7910 | place_entity(cfs_rq, se, 0); | |
7911 | se->vruntime -= cfs_rq->min_vruntime; | |
7912 | } | |
9ee474f5 | 7913 | |
141965c7 | 7914 | #ifdef CONFIG_SMP |
9ee474f5 PT |
7915 | /* |
7916 | * Remove our load from contribution when we leave sched_fair | |
7917 | * and ensure we don't carry in an old decay_count if we | |
7918 | * switch back. | |
7919 | */ | |
87e3c8ae KT |
7920 | if (se->avg.decay_count) { |
7921 | __synchronize_entity_decay(se); | |
7922 | subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib); | |
9ee474f5 PT |
7923 | } |
7924 | #endif | |
da7a735e PZ |
7925 | } |
7926 | ||
cb469845 SR |
7927 | /* |
7928 | * We switched to the sched_fair class. | |
7929 | */ | |
da7a735e | 7930 | static void switched_to_fair(struct rq *rq, struct task_struct *p) |
cb469845 | 7931 | { |
eb7a59b2 | 7932 | #ifdef CONFIG_FAIR_GROUP_SCHED |
f36c019c | 7933 | struct sched_entity *se = &p->se; |
eb7a59b2 M |
7934 | /* |
7935 | * Since the real-depth could have been changed (only FAIR | |
7936 | * class maintain depth value), reset depth properly. | |
7937 | */ | |
7938 | se->depth = se->parent ? se->parent->depth + 1 : 0; | |
7939 | #endif | |
da0c1e65 | 7940 | if (!task_on_rq_queued(p)) |
da7a735e PZ |
7941 | return; |
7942 | ||
cb469845 SR |
7943 | /* |
7944 | * We were most likely switched from sched_rt, so | |
7945 | * kick off the schedule if running, otherwise just see | |
7946 | * if we can still preempt the current task. | |
7947 | */ | |
da7a735e | 7948 | if (rq->curr == p) |
8875125e | 7949 | resched_curr(rq); |
cb469845 | 7950 | else |
15afe09b | 7951 | check_preempt_curr(rq, p, 0); |
cb469845 SR |
7952 | } |
7953 | ||
83b699ed SV |
7954 | /* Account for a task changing its policy or group. |
7955 | * | |
7956 | * This routine is mostly called to set cfs_rq->curr field when a task | |
7957 | * migrates between groups/classes. | |
7958 | */ | |
7959 | static void set_curr_task_fair(struct rq *rq) | |
7960 | { | |
7961 | struct sched_entity *se = &rq->curr->se; | |
7962 | ||
ec12cb7f PT |
7963 | for_each_sched_entity(se) { |
7964 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
7965 | ||
7966 | set_next_entity(cfs_rq, se); | |
7967 | /* ensure bandwidth has been allocated on our new cfs_rq */ | |
7968 | account_cfs_rq_runtime(cfs_rq, 0); | |
7969 | } | |
83b699ed SV |
7970 | } |
7971 | ||
029632fb PZ |
7972 | void init_cfs_rq(struct cfs_rq *cfs_rq) |
7973 | { | |
7974 | cfs_rq->tasks_timeline = RB_ROOT; | |
029632fb PZ |
7975 | cfs_rq->min_vruntime = (u64)(-(1LL << 20)); |
7976 | #ifndef CONFIG_64BIT | |
7977 | cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; | |
7978 | #endif | |
141965c7 | 7979 | #ifdef CONFIG_SMP |
9ee474f5 | 7980 | atomic64_set(&cfs_rq->decay_counter, 1); |
2509940f | 7981 | atomic_long_set(&cfs_rq->removed_load, 0); |
9ee474f5 | 7982 | #endif |
029632fb PZ |
7983 | } |
7984 | ||
810b3817 | 7985 | #ifdef CONFIG_FAIR_GROUP_SCHED |
da0c1e65 | 7986 | static void task_move_group_fair(struct task_struct *p, int queued) |
810b3817 | 7987 | { |
fed14d45 | 7988 | struct sched_entity *se = &p->se; |
aff3e498 | 7989 | struct cfs_rq *cfs_rq; |
fed14d45 | 7990 | |
b2b5ce02 PZ |
7991 | /* |
7992 | * If the task was not on the rq at the time of this cgroup movement | |
7993 | * it must have been asleep, sleeping tasks keep their ->vruntime | |
7994 | * absolute on their old rq until wakeup (needed for the fair sleeper | |
7995 | * bonus in place_entity()). | |
7996 | * | |
7997 | * If it was on the rq, we've just 'preempted' it, which does convert | |
7998 | * ->vruntime to a relative base. | |
7999 | * | |
8000 | * Make sure both cases convert their relative position when migrating | |
8001 | * to another cgroup's rq. This does somewhat interfere with the | |
8002 | * fair sleeper stuff for the first placement, but who cares. | |
8003 | */ | |
7ceff013 | 8004 | /* |
da0c1e65 | 8005 | * When !queued, vruntime of the task has usually NOT been normalized. |
7ceff013 DN |
8006 | * But there are some cases where it has already been normalized: |
8007 | * | |
8008 | * - Moving a forked child which is waiting for being woken up by | |
8009 | * wake_up_new_task(). | |
62af3783 DN |
8010 | * - Moving a task which has been woken up by try_to_wake_up() and |
8011 | * waiting for actually being woken up by sched_ttwu_pending(). | |
7ceff013 DN |
8012 | * |
8013 | * To prevent boost or penalty in the new cfs_rq caused by delta | |
8014 | * min_vruntime between the two cfs_rqs, we skip vruntime adjustment. | |
8015 | */ | |
da0c1e65 KT |
8016 | if (!queued && (!se->sum_exec_runtime || p->state == TASK_WAKING)) |
8017 | queued = 1; | |
7ceff013 | 8018 | |
da0c1e65 | 8019 | if (!queued) |
fed14d45 | 8020 | se->vruntime -= cfs_rq_of(se)->min_vruntime; |
b2b5ce02 | 8021 | set_task_rq(p, task_cpu(p)); |
fed14d45 | 8022 | se->depth = se->parent ? se->parent->depth + 1 : 0; |
da0c1e65 | 8023 | if (!queued) { |
fed14d45 PZ |
8024 | cfs_rq = cfs_rq_of(se); |
8025 | se->vruntime += cfs_rq->min_vruntime; | |
aff3e498 PT |
8026 | #ifdef CONFIG_SMP |
8027 | /* | |
8028 | * migrate_task_rq_fair() will have removed our previous | |
8029 | * contribution, but we must synchronize for ongoing future | |
8030 | * decay. | |
8031 | */ | |
fed14d45 PZ |
8032 | se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter); |
8033 | cfs_rq->blocked_load_avg += se->avg.load_avg_contrib; | |
aff3e498 PT |
8034 | #endif |
8035 | } | |
810b3817 | 8036 | } |
029632fb PZ |
8037 | |
8038 | void free_fair_sched_group(struct task_group *tg) | |
8039 | { | |
8040 | int i; | |
8041 | ||
8042 | destroy_cfs_bandwidth(tg_cfs_bandwidth(tg)); | |
8043 | ||
8044 | for_each_possible_cpu(i) { | |
8045 | if (tg->cfs_rq) | |
8046 | kfree(tg->cfs_rq[i]); | |
8047 | if (tg->se) | |
8048 | kfree(tg->se[i]); | |
8049 | } | |
8050 | ||
8051 | kfree(tg->cfs_rq); | |
8052 | kfree(tg->se); | |
8053 | } | |
8054 | ||
8055 | int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) | |
8056 | { | |
8057 | struct cfs_rq *cfs_rq; | |
8058 | struct sched_entity *se; | |
8059 | int i; | |
8060 | ||
8061 | tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL); | |
8062 | if (!tg->cfs_rq) | |
8063 | goto err; | |
8064 | tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL); | |
8065 | if (!tg->se) | |
8066 | goto err; | |
8067 | ||
8068 | tg->shares = NICE_0_LOAD; | |
8069 | ||
8070 | init_cfs_bandwidth(tg_cfs_bandwidth(tg)); | |
8071 | ||
8072 | for_each_possible_cpu(i) { | |
8073 | cfs_rq = kzalloc_node(sizeof(struct cfs_rq), | |
8074 | GFP_KERNEL, cpu_to_node(i)); | |
8075 | if (!cfs_rq) | |
8076 | goto err; | |
8077 | ||
8078 | se = kzalloc_node(sizeof(struct sched_entity), | |
8079 | GFP_KERNEL, cpu_to_node(i)); | |
8080 | if (!se) | |
8081 | goto err_free_rq; | |
8082 | ||
8083 | init_cfs_rq(cfs_rq); | |
8084 | init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]); | |
8085 | } | |
8086 | ||
8087 | return 1; | |
8088 | ||
8089 | err_free_rq: | |
8090 | kfree(cfs_rq); | |
8091 | err: | |
8092 | return 0; | |
8093 | } | |
8094 | ||
8095 | void unregister_fair_sched_group(struct task_group *tg, int cpu) | |
8096 | { | |
8097 | struct rq *rq = cpu_rq(cpu); | |
8098 | unsigned long flags; | |
8099 | ||
8100 | /* | |
8101 | * Only empty task groups can be destroyed; so we can speculatively | |
8102 | * check on_list without danger of it being re-added. | |
8103 | */ | |
8104 | if (!tg->cfs_rq[cpu]->on_list) | |
8105 | return; | |
8106 | ||
8107 | raw_spin_lock_irqsave(&rq->lock, flags); | |
8108 | list_del_leaf_cfs_rq(tg->cfs_rq[cpu]); | |
8109 | raw_spin_unlock_irqrestore(&rq->lock, flags); | |
8110 | } | |
8111 | ||
8112 | void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, | |
8113 | struct sched_entity *se, int cpu, | |
8114 | struct sched_entity *parent) | |
8115 | { | |
8116 | struct rq *rq = cpu_rq(cpu); | |
8117 | ||
8118 | cfs_rq->tg = tg; | |
8119 | cfs_rq->rq = rq; | |
029632fb PZ |
8120 | init_cfs_rq_runtime(cfs_rq); |
8121 | ||
8122 | tg->cfs_rq[cpu] = cfs_rq; | |
8123 | tg->se[cpu] = se; | |
8124 | ||
8125 | /* se could be NULL for root_task_group */ | |
8126 | if (!se) | |
8127 | return; | |
8128 | ||
fed14d45 | 8129 | if (!parent) { |
029632fb | 8130 | se->cfs_rq = &rq->cfs; |
fed14d45 PZ |
8131 | se->depth = 0; |
8132 | } else { | |
029632fb | 8133 | se->cfs_rq = parent->my_q; |
fed14d45 PZ |
8134 | se->depth = parent->depth + 1; |
8135 | } | |
029632fb PZ |
8136 | |
8137 | se->my_q = cfs_rq; | |
0ac9b1c2 PT |
8138 | /* guarantee group entities always have weight */ |
8139 | update_load_set(&se->load, NICE_0_LOAD); | |
029632fb PZ |
8140 | se->parent = parent; |
8141 | } | |
8142 | ||
8143 | static DEFINE_MUTEX(shares_mutex); | |
8144 | ||
8145 | int sched_group_set_shares(struct task_group *tg, unsigned long shares) | |
8146 | { | |
8147 | int i; | |
8148 | unsigned long flags; | |
8149 | ||
8150 | /* | |
8151 | * We can't change the weight of the root cgroup. | |
8152 | */ | |
8153 | if (!tg->se[0]) | |
8154 | return -EINVAL; | |
8155 | ||
8156 | shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES)); | |
8157 | ||
8158 | mutex_lock(&shares_mutex); | |
8159 | if (tg->shares == shares) | |
8160 | goto done; | |
8161 | ||
8162 | tg->shares = shares; | |
8163 | for_each_possible_cpu(i) { | |
8164 | struct rq *rq = cpu_rq(i); | |
8165 | struct sched_entity *se; | |
8166 | ||
8167 | se = tg->se[i]; | |
8168 | /* Propagate contribution to hierarchy */ | |
8169 | raw_spin_lock_irqsave(&rq->lock, flags); | |
71b1da46 FW |
8170 | |
8171 | /* Possible calls to update_curr() need rq clock */ | |
8172 | update_rq_clock(rq); | |
17bc14b7 | 8173 | for_each_sched_entity(se) |
029632fb PZ |
8174 | update_cfs_shares(group_cfs_rq(se)); |
8175 | raw_spin_unlock_irqrestore(&rq->lock, flags); | |
8176 | } | |
8177 | ||
8178 | done: | |
8179 | mutex_unlock(&shares_mutex); | |
8180 | return 0; | |
8181 | } | |
8182 | #else /* CONFIG_FAIR_GROUP_SCHED */ | |
8183 | ||
8184 | void free_fair_sched_group(struct task_group *tg) { } | |
8185 | ||
8186 | int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) | |
8187 | { | |
8188 | return 1; | |
8189 | } | |
8190 | ||
8191 | void unregister_fair_sched_group(struct task_group *tg, int cpu) { } | |
8192 | ||
8193 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
8194 | ||
810b3817 | 8195 | |
6d686f45 | 8196 | static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task) |
0d721cea PW |
8197 | { |
8198 | struct sched_entity *se = &task->se; | |
0d721cea PW |
8199 | unsigned int rr_interval = 0; |
8200 | ||
8201 | /* | |
8202 | * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise | |
8203 | * idle runqueue: | |
8204 | */ | |
0d721cea | 8205 | if (rq->cfs.load.weight) |
a59f4e07 | 8206 | rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se)); |
0d721cea PW |
8207 | |
8208 | return rr_interval; | |
8209 | } | |
8210 | ||
bf0f6f24 IM |
8211 | /* |
8212 | * All the scheduling class methods: | |
8213 | */ | |
029632fb | 8214 | const struct sched_class fair_sched_class = { |
5522d5d5 | 8215 | .next = &idle_sched_class, |
bf0f6f24 IM |
8216 | .enqueue_task = enqueue_task_fair, |
8217 | .dequeue_task = dequeue_task_fair, | |
8218 | .yield_task = yield_task_fair, | |
d95f4122 | 8219 | .yield_to_task = yield_to_task_fair, |
bf0f6f24 | 8220 | |
2e09bf55 | 8221 | .check_preempt_curr = check_preempt_wakeup, |
bf0f6f24 IM |
8222 | |
8223 | .pick_next_task = pick_next_task_fair, | |
8224 | .put_prev_task = put_prev_task_fair, | |
8225 | ||
681f3e68 | 8226 | #ifdef CONFIG_SMP |
4ce72a2c | 8227 | .select_task_rq = select_task_rq_fair, |
0a74bef8 | 8228 | .migrate_task_rq = migrate_task_rq_fair, |
141965c7 | 8229 | |
0bcdcf28 CE |
8230 | .rq_online = rq_online_fair, |
8231 | .rq_offline = rq_offline_fair, | |
88ec22d3 PZ |
8232 | |
8233 | .task_waking = task_waking_fair, | |
681f3e68 | 8234 | #endif |
bf0f6f24 | 8235 | |
83b699ed | 8236 | .set_curr_task = set_curr_task_fair, |
bf0f6f24 | 8237 | .task_tick = task_tick_fair, |
cd29fe6f | 8238 | .task_fork = task_fork_fair, |
cb469845 SR |
8239 | |
8240 | .prio_changed = prio_changed_fair, | |
da7a735e | 8241 | .switched_from = switched_from_fair, |
cb469845 | 8242 | .switched_to = switched_to_fair, |
810b3817 | 8243 | |
0d721cea PW |
8244 | .get_rr_interval = get_rr_interval_fair, |
8245 | ||
6e998916 SG |
8246 | .update_curr = update_curr_fair, |
8247 | ||
810b3817 | 8248 | #ifdef CONFIG_FAIR_GROUP_SCHED |
b2b5ce02 | 8249 | .task_move_group = task_move_group_fair, |
810b3817 | 8250 | #endif |
bf0f6f24 IM |
8251 | }; |
8252 | ||
8253 | #ifdef CONFIG_SCHED_DEBUG | |
029632fb | 8254 | void print_cfs_stats(struct seq_file *m, int cpu) |
bf0f6f24 | 8255 | { |
bf0f6f24 IM |
8256 | struct cfs_rq *cfs_rq; |
8257 | ||
5973e5b9 | 8258 | rcu_read_lock(); |
c3b64f1e | 8259 | for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) |
5cef9eca | 8260 | print_cfs_rq(m, cpu, cfs_rq); |
5973e5b9 | 8261 | rcu_read_unlock(); |
bf0f6f24 IM |
8262 | } |
8263 | #endif | |
029632fb PZ |
8264 | |
8265 | __init void init_sched_fair_class(void) | |
8266 | { | |
8267 | #ifdef CONFIG_SMP | |
8268 | open_softirq(SCHED_SOFTIRQ, run_rebalance_domains); | |
8269 | ||
3451d024 | 8270 | #ifdef CONFIG_NO_HZ_COMMON |
554cecaf | 8271 | nohz.next_balance = jiffies; |
029632fb | 8272 | zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); |
71325960 | 8273 | cpu_notifier(sched_ilb_notifier, 0); |
029632fb PZ |
8274 | #endif |
8275 | #endif /* SMP */ | |
8276 | ||
8277 | } |