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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> | |
18 | * | |
19 | * Adaptive scheduling granularity, math enhancements by Peter Zijlstra | |
20 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> | |
21 | */ | |
22 | ||
23 | #include <linux/latencytop.h> | |
24 | ||
25 | /* | |
26 | * Targeted preemption latency for CPU-bound tasks: | |
27 | * (default: 20ms * (1 + ilog(ncpus)), units: nanoseconds) | |
28 | * | |
29 | * NOTE: this latency value is not the same as the concept of | |
30 | * 'timeslice length' - timeslices in CFS are of variable length | |
31 | * and have no persistent notion like in traditional, time-slice | |
32 | * based scheduling concepts. | |
33 | * | |
34 | * (to see the precise effective timeslice length of your workload, | |
35 | * run vmstat and monitor the context-switches (cs) field) | |
36 | */ | |
37 | unsigned int sysctl_sched_latency = 20000000ULL; | |
38 | ||
39 | /* | |
40 | * Minimal preemption granularity for CPU-bound tasks: | |
41 | * (default: 4 msec * (1 + ilog(ncpus)), units: nanoseconds) | |
42 | */ | |
43 | unsigned int sysctl_sched_min_granularity = 4000000ULL; | |
44 | ||
45 | /* | |
46 | * is kept at sysctl_sched_latency / sysctl_sched_min_granularity | |
47 | */ | |
48 | static unsigned int sched_nr_latency = 5; | |
49 | ||
50 | /* | |
51 | * After fork, child runs first. (default) If set to 0 then | |
52 | * parent will (try to) run first. | |
53 | */ | |
54 | const_debug unsigned int sysctl_sched_child_runs_first = 1; | |
55 | ||
56 | /* | |
57 | * sys_sched_yield() compat mode | |
58 | * | |
59 | * This option switches the agressive yield implementation of the | |
60 | * old scheduler back on. | |
61 | */ | |
62 | unsigned int __read_mostly sysctl_sched_compat_yield; | |
63 | ||
64 | /* | |
65 | * SCHED_OTHER wake-up granularity. | |
66 | * (default: 5 msec * (1 + ilog(ncpus)), units: nanoseconds) | |
67 | * | |
68 | * This option delays the preemption effects of decoupled workloads | |
69 | * and reduces their over-scheduling. Synchronous workloads will still | |
70 | * have immediate wakeup/sleep latencies. | |
71 | */ | |
72 | unsigned int sysctl_sched_wakeup_granularity = 5000000UL; | |
73 | ||
74 | const_debug unsigned int sysctl_sched_migration_cost = 500000UL; | |
75 | ||
76 | /************************************************************** | |
77 | * CFS operations on generic schedulable entities: | |
78 | */ | |
79 | ||
80 | static inline struct task_struct *task_of(struct sched_entity *se) | |
81 | { | |
82 | return container_of(se, struct task_struct, se); | |
83 | } | |
84 | ||
85 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
86 | ||
87 | /* cpu runqueue to which this cfs_rq is attached */ | |
88 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) | |
89 | { | |
90 | return cfs_rq->rq; | |
91 | } | |
92 | ||
93 | /* An entity is a task if it doesn't "own" a runqueue */ | |
94 | #define entity_is_task(se) (!se->my_q) | |
95 | ||
96 | /* Walk up scheduling entities hierarchy */ | |
97 | #define for_each_sched_entity(se) \ | |
98 | for (; se; se = se->parent) | |
99 | ||
100 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) | |
101 | { | |
102 | return p->se.cfs_rq; | |
103 | } | |
104 | ||
105 | /* runqueue on which this entity is (to be) queued */ | |
106 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) | |
107 | { | |
108 | return se->cfs_rq; | |
109 | } | |
110 | ||
111 | /* runqueue "owned" by this group */ | |
112 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
113 | { | |
114 | return grp->my_q; | |
115 | } | |
116 | ||
117 | /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on | |
118 | * another cpu ('this_cpu') | |
119 | */ | |
120 | static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu) | |
121 | { | |
122 | return cfs_rq->tg->cfs_rq[this_cpu]; | |
123 | } | |
124 | ||
125 | /* Iterate thr' all leaf cfs_rq's on a runqueue */ | |
126 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ | |
127 | list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) | |
128 | ||
129 | /* Do the two (enqueued) entities belong to the same group ? */ | |
130 | static inline int | |
131 | is_same_group(struct sched_entity *se, struct sched_entity *pse) | |
132 | { | |
133 | if (se->cfs_rq == pse->cfs_rq) | |
134 | return 1; | |
135 | ||
136 | return 0; | |
137 | } | |
138 | ||
139 | static inline struct sched_entity *parent_entity(struct sched_entity *se) | |
140 | { | |
141 | return se->parent; | |
142 | } | |
143 | ||
144 | #else /* CONFIG_FAIR_GROUP_SCHED */ | |
145 | ||
146 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) | |
147 | { | |
148 | return container_of(cfs_rq, struct rq, cfs); | |
149 | } | |
150 | ||
151 | #define entity_is_task(se) 1 | |
152 | ||
153 | #define for_each_sched_entity(se) \ | |
154 | for (; se; se = NULL) | |
155 | ||
156 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) | |
157 | { | |
158 | return &task_rq(p)->cfs; | |
159 | } | |
160 | ||
161 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) | |
162 | { | |
163 | struct task_struct *p = task_of(se); | |
164 | struct rq *rq = task_rq(p); | |
165 | ||
166 | return &rq->cfs; | |
167 | } | |
168 | ||
169 | /* runqueue "owned" by this group */ | |
170 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
171 | { | |
172 | return NULL; | |
173 | } | |
174 | ||
175 | static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu) | |
176 | { | |
177 | return &cpu_rq(this_cpu)->cfs; | |
178 | } | |
179 | ||
180 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ | |
181 | for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) | |
182 | ||
183 | static inline int | |
184 | is_same_group(struct sched_entity *se, struct sched_entity *pse) | |
185 | { | |
186 | return 1; | |
187 | } | |
188 | ||
189 | static inline struct sched_entity *parent_entity(struct sched_entity *se) | |
190 | { | |
191 | return NULL; | |
192 | } | |
193 | ||
194 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
195 | ||
196 | ||
197 | /************************************************************** | |
198 | * Scheduling class tree data structure manipulation methods: | |
199 | */ | |
200 | ||
201 | static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime) | |
202 | { | |
203 | s64 delta = (s64)(vruntime - min_vruntime); | |
204 | if (delta > 0) | |
205 | min_vruntime = vruntime; | |
206 | ||
207 | return min_vruntime; | |
208 | } | |
209 | ||
210 | static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime) | |
211 | { | |
212 | s64 delta = (s64)(vruntime - min_vruntime); | |
213 | if (delta < 0) | |
214 | min_vruntime = vruntime; | |
215 | ||
216 | return min_vruntime; | |
217 | } | |
218 | ||
219 | static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
220 | { | |
221 | return se->vruntime - cfs_rq->min_vruntime; | |
222 | } | |
223 | ||
224 | /* | |
225 | * Enqueue an entity into the rb-tree: | |
226 | */ | |
227 | static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
228 | { | |
229 | struct rb_node **link = &cfs_rq->tasks_timeline.rb_node; | |
230 | struct rb_node *parent = NULL; | |
231 | struct sched_entity *entry; | |
232 | s64 key = entity_key(cfs_rq, se); | |
233 | int leftmost = 1; | |
234 | ||
235 | /* | |
236 | * Find the right place in the rbtree: | |
237 | */ | |
238 | while (*link) { | |
239 | parent = *link; | |
240 | entry = rb_entry(parent, struct sched_entity, run_node); | |
241 | /* | |
242 | * We dont care about collisions. Nodes with | |
243 | * the same key stay together. | |
244 | */ | |
245 | if (key < entity_key(cfs_rq, entry)) { | |
246 | link = &parent->rb_left; | |
247 | } else { | |
248 | link = &parent->rb_right; | |
249 | leftmost = 0; | |
250 | } | |
251 | } | |
252 | ||
253 | /* | |
254 | * Maintain a cache of leftmost tree entries (it is frequently | |
255 | * used): | |
256 | */ | |
257 | if (leftmost) { | |
258 | cfs_rq->rb_leftmost = &se->run_node; | |
259 | /* | |
260 | * maintain cfs_rq->min_vruntime to be a monotonic increasing | |
261 | * value tracking the leftmost vruntime in the tree. | |
262 | */ | |
263 | cfs_rq->min_vruntime = | |
264 | max_vruntime(cfs_rq->min_vruntime, se->vruntime); | |
265 | } | |
266 | ||
267 | rb_link_node(&se->run_node, parent, link); | |
268 | rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline); | |
269 | } | |
270 | ||
271 | static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
272 | { | |
273 | if (cfs_rq->rb_leftmost == &se->run_node) { | |
274 | struct rb_node *next_node; | |
275 | struct sched_entity *next; | |
276 | ||
277 | next_node = rb_next(&se->run_node); | |
278 | cfs_rq->rb_leftmost = next_node; | |
279 | ||
280 | if (next_node) { | |
281 | next = rb_entry(next_node, | |
282 | struct sched_entity, run_node); | |
283 | cfs_rq->min_vruntime = | |
284 | max_vruntime(cfs_rq->min_vruntime, | |
285 | next->vruntime); | |
286 | } | |
287 | } | |
288 | ||
289 | if (cfs_rq->next == se) | |
290 | cfs_rq->next = NULL; | |
291 | ||
292 | rb_erase(&se->run_node, &cfs_rq->tasks_timeline); | |
293 | } | |
294 | ||
295 | static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq) | |
296 | { | |
297 | return cfs_rq->rb_leftmost; | |
298 | } | |
299 | ||
300 | static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq) | |
301 | { | |
302 | return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node); | |
303 | } | |
304 | ||
305 | static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) | |
306 | { | |
307 | struct rb_node *last = rb_last(&cfs_rq->tasks_timeline); | |
308 | ||
309 | if (!last) | |
310 | return NULL; | |
311 | ||
312 | return rb_entry(last, struct sched_entity, run_node); | |
313 | } | |
314 | ||
315 | /************************************************************** | |
316 | * Scheduling class statistics methods: | |
317 | */ | |
318 | ||
319 | #ifdef CONFIG_SCHED_DEBUG | |
320 | int sched_nr_latency_handler(struct ctl_table *table, int write, | |
321 | struct file *filp, void __user *buffer, size_t *lenp, | |
322 | loff_t *ppos) | |
323 | { | |
324 | int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos); | |
325 | ||
326 | if (ret || !write) | |
327 | return ret; | |
328 | ||
329 | sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency, | |
330 | sysctl_sched_min_granularity); | |
331 | ||
332 | return 0; | |
333 | } | |
334 | #endif | |
335 | ||
336 | /* | |
337 | * delta *= w / rw | |
338 | */ | |
339 | static inline unsigned long | |
340 | calc_delta_weight(unsigned long delta, struct sched_entity *se) | |
341 | { | |
342 | for_each_sched_entity(se) { | |
343 | delta = calc_delta_mine(delta, | |
344 | se->load.weight, &cfs_rq_of(se)->load); | |
345 | } | |
346 | ||
347 | return delta; | |
348 | } | |
349 | ||
350 | /* | |
351 | * delta *= rw / w | |
352 | */ | |
353 | static inline unsigned long | |
354 | calc_delta_fair(unsigned long delta, struct sched_entity *se) | |
355 | { | |
356 | for_each_sched_entity(se) { | |
357 | delta = calc_delta_mine(delta, | |
358 | cfs_rq_of(se)->load.weight, &se->load); | |
359 | } | |
360 | ||
361 | return delta; | |
362 | } | |
363 | ||
364 | /* | |
365 | * The idea is to set a period in which each task runs once. | |
366 | * | |
367 | * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch | |
368 | * this period because otherwise the slices get too small. | |
369 | * | |
370 | * p = (nr <= nl) ? l : l*nr/nl | |
371 | */ | |
372 | static u64 __sched_period(unsigned long nr_running) | |
373 | { | |
374 | u64 period = sysctl_sched_latency; | |
375 | unsigned long nr_latency = sched_nr_latency; | |
376 | ||
377 | if (unlikely(nr_running > nr_latency)) { | |
378 | period = sysctl_sched_min_granularity; | |
379 | period *= nr_running; | |
380 | } | |
381 | ||
382 | return period; | |
383 | } | |
384 | ||
385 | /* | |
386 | * We calculate the wall-time slice from the period by taking a part | |
387 | * proportional to the weight. | |
388 | * | |
389 | * s = p*w/rw | |
390 | */ | |
391 | static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
392 | { | |
393 | return calc_delta_weight(__sched_period(cfs_rq->nr_running), se); | |
394 | } | |
395 | ||
396 | /* | |
397 | * We calculate the vruntime slice of a to be inserted task | |
398 | * | |
399 | * vs = s*rw/w = p | |
400 | */ | |
401 | static u64 sched_vslice_add(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
402 | { | |
403 | unsigned long nr_running = cfs_rq->nr_running; | |
404 | ||
405 | if (!se->on_rq) | |
406 | nr_running++; | |
407 | ||
408 | return __sched_period(nr_running); | |
409 | } | |
410 | ||
411 | /* | |
412 | * The goal of calc_delta_asym() is to be asymmetrically around NICE_0_LOAD, in | |
413 | * that it favours >=0 over <0. | |
414 | * | |
415 | * -20 | | |
416 | * | | |
417 | * 0 --------+------- | |
418 | * .' | |
419 | * 19 .' | |
420 | * | |
421 | */ | |
422 | static unsigned long | |
423 | calc_delta_asym(unsigned long delta, struct sched_entity *se) | |
424 | { | |
425 | struct load_weight lw = { | |
426 | .weight = NICE_0_LOAD, | |
427 | .inv_weight = 1UL << (WMULT_SHIFT-NICE_0_SHIFT) | |
428 | }; | |
429 | ||
430 | for_each_sched_entity(se) { | |
431 | struct load_weight *se_lw = &se->load; | |
432 | unsigned long rw = cfs_rq_of(se)->load.weight; | |
433 | ||
434 | #ifdef CONFIG_FAIR_SCHED_GROUP | |
435 | struct cfs_rq *cfs_rq = se->my_q; | |
436 | struct task_group *tg = NULL | |
437 | ||
438 | if (cfs_rq) | |
439 | tg = cfs_rq->tg; | |
440 | ||
441 | if (tg && tg->shares < NICE_0_LOAD) { | |
442 | /* | |
443 | * scale shares to what it would have been had | |
444 | * tg->weight been NICE_0_LOAD: | |
445 | * | |
446 | * weight = 1024 * shares / tg->weight | |
447 | */ | |
448 | lw.weight *= se->load.weight; | |
449 | lw.weight /= tg->shares; | |
450 | ||
451 | lw.inv_weight = 0; | |
452 | ||
453 | se_lw = &lw; | |
454 | rw += lw.weight - se->load.weight; | |
455 | } else | |
456 | #endif | |
457 | ||
458 | if (se->load.weight < NICE_0_LOAD) { | |
459 | se_lw = &lw; | |
460 | rw += NICE_0_LOAD - se->load.weight; | |
461 | } | |
462 | ||
463 | delta = calc_delta_mine(delta, rw, se_lw); | |
464 | } | |
465 | ||
466 | return delta; | |
467 | } | |
468 | ||
469 | /* | |
470 | * Update the current task's runtime statistics. Skip current tasks that | |
471 | * are not in our scheduling class. | |
472 | */ | |
473 | static inline void | |
474 | __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr, | |
475 | unsigned long delta_exec) | |
476 | { | |
477 | unsigned long delta_exec_weighted; | |
478 | ||
479 | schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max)); | |
480 | ||
481 | curr->sum_exec_runtime += delta_exec; | |
482 | schedstat_add(cfs_rq, exec_clock, delta_exec); | |
483 | delta_exec_weighted = calc_delta_fair(delta_exec, curr); | |
484 | curr->vruntime += delta_exec_weighted; | |
485 | } | |
486 | ||
487 | static void update_curr(struct cfs_rq *cfs_rq) | |
488 | { | |
489 | struct sched_entity *curr = cfs_rq->curr; | |
490 | u64 now = rq_of(cfs_rq)->clock; | |
491 | unsigned long delta_exec; | |
492 | ||
493 | if (unlikely(!curr)) | |
494 | return; | |
495 | ||
496 | /* | |
497 | * Get the amount of time the current task was running | |
498 | * since the last time we changed load (this cannot | |
499 | * overflow on 32 bits): | |
500 | */ | |
501 | delta_exec = (unsigned long)(now - curr->exec_start); | |
502 | ||
503 | __update_curr(cfs_rq, curr, delta_exec); | |
504 | curr->exec_start = now; | |
505 | ||
506 | if (entity_is_task(curr)) { | |
507 | struct task_struct *curtask = task_of(curr); | |
508 | ||
509 | cpuacct_charge(curtask, delta_exec); | |
510 | } | |
511 | } | |
512 | ||
513 | static inline void | |
514 | update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
515 | { | |
516 | schedstat_set(se->wait_start, rq_of(cfs_rq)->clock); | |
517 | } | |
518 | ||
519 | /* | |
520 | * Task is being enqueued - update stats: | |
521 | */ | |
522 | static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
523 | { | |
524 | /* | |
525 | * Are we enqueueing a waiting task? (for current tasks | |
526 | * a dequeue/enqueue event is a NOP) | |
527 | */ | |
528 | if (se != cfs_rq->curr) | |
529 | update_stats_wait_start(cfs_rq, se); | |
530 | } | |
531 | ||
532 | static void | |
533 | update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
534 | { | |
535 | schedstat_set(se->wait_max, max(se->wait_max, | |
536 | rq_of(cfs_rq)->clock - se->wait_start)); | |
537 | schedstat_set(se->wait_count, se->wait_count + 1); | |
538 | schedstat_set(se->wait_sum, se->wait_sum + | |
539 | rq_of(cfs_rq)->clock - se->wait_start); | |
540 | schedstat_set(se->wait_start, 0); | |
541 | } | |
542 | ||
543 | static inline void | |
544 | update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
545 | { | |
546 | /* | |
547 | * Mark the end of the wait period if dequeueing a | |
548 | * waiting task: | |
549 | */ | |
550 | if (se != cfs_rq->curr) | |
551 | update_stats_wait_end(cfs_rq, se); | |
552 | } | |
553 | ||
554 | /* | |
555 | * We are picking a new current task - update its stats: | |
556 | */ | |
557 | static inline void | |
558 | update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
559 | { | |
560 | /* | |
561 | * We are starting a new run period: | |
562 | */ | |
563 | se->exec_start = rq_of(cfs_rq)->clock; | |
564 | } | |
565 | ||
566 | /************************************************** | |
567 | * Scheduling class queueing methods: | |
568 | */ | |
569 | ||
570 | #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED | |
571 | static void | |
572 | add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight) | |
573 | { | |
574 | cfs_rq->task_weight += weight; | |
575 | } | |
576 | #else | |
577 | static inline void | |
578 | add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight) | |
579 | { | |
580 | } | |
581 | #endif | |
582 | ||
583 | static void | |
584 | account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
585 | { | |
586 | update_load_add(&cfs_rq->load, se->load.weight); | |
587 | if (!parent_entity(se)) | |
588 | inc_cpu_load(rq_of(cfs_rq), se->load.weight); | |
589 | if (entity_is_task(se)) | |
590 | add_cfs_task_weight(cfs_rq, se->load.weight); | |
591 | cfs_rq->nr_running++; | |
592 | se->on_rq = 1; | |
593 | list_add(&se->group_node, &cfs_rq->tasks); | |
594 | } | |
595 | ||
596 | static void | |
597 | account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
598 | { | |
599 | update_load_sub(&cfs_rq->load, se->load.weight); | |
600 | if (!parent_entity(se)) | |
601 | dec_cpu_load(rq_of(cfs_rq), se->load.weight); | |
602 | if (entity_is_task(se)) | |
603 | add_cfs_task_weight(cfs_rq, -se->load.weight); | |
604 | cfs_rq->nr_running--; | |
605 | se->on_rq = 0; | |
606 | list_del_init(&se->group_node); | |
607 | } | |
608 | ||
609 | static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
610 | { | |
611 | #ifdef CONFIG_SCHEDSTATS | |
612 | if (se->sleep_start) { | |
613 | u64 delta = rq_of(cfs_rq)->clock - se->sleep_start; | |
614 | struct task_struct *tsk = task_of(se); | |
615 | ||
616 | if ((s64)delta < 0) | |
617 | delta = 0; | |
618 | ||
619 | if (unlikely(delta > se->sleep_max)) | |
620 | se->sleep_max = delta; | |
621 | ||
622 | se->sleep_start = 0; | |
623 | se->sum_sleep_runtime += delta; | |
624 | ||
625 | account_scheduler_latency(tsk, delta >> 10, 1); | |
626 | } | |
627 | if (se->block_start) { | |
628 | u64 delta = rq_of(cfs_rq)->clock - se->block_start; | |
629 | struct task_struct *tsk = task_of(se); | |
630 | ||
631 | if ((s64)delta < 0) | |
632 | delta = 0; | |
633 | ||
634 | if (unlikely(delta > se->block_max)) | |
635 | se->block_max = delta; | |
636 | ||
637 | se->block_start = 0; | |
638 | se->sum_sleep_runtime += delta; | |
639 | ||
640 | /* | |
641 | * Blocking time is in units of nanosecs, so shift by 20 to | |
642 | * get a milliseconds-range estimation of the amount of | |
643 | * time that the task spent sleeping: | |
644 | */ | |
645 | if (unlikely(prof_on == SLEEP_PROFILING)) { | |
646 | ||
647 | profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk), | |
648 | delta >> 20); | |
649 | } | |
650 | account_scheduler_latency(tsk, delta >> 10, 0); | |
651 | } | |
652 | #endif | |
653 | } | |
654 | ||
655 | static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
656 | { | |
657 | #ifdef CONFIG_SCHED_DEBUG | |
658 | s64 d = se->vruntime - cfs_rq->min_vruntime; | |
659 | ||
660 | if (d < 0) | |
661 | d = -d; | |
662 | ||
663 | if (d > 3*sysctl_sched_latency) | |
664 | schedstat_inc(cfs_rq, nr_spread_over); | |
665 | #endif | |
666 | } | |
667 | ||
668 | static void | |
669 | place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) | |
670 | { | |
671 | u64 vruntime; | |
672 | ||
673 | if (first_fair(cfs_rq)) { | |
674 | vruntime = min_vruntime(cfs_rq->min_vruntime, | |
675 | __pick_next_entity(cfs_rq)->vruntime); | |
676 | } else | |
677 | vruntime = cfs_rq->min_vruntime; | |
678 | ||
679 | /* | |
680 | * The 'current' period is already promised to the current tasks, | |
681 | * however the extra weight of the new task will slow them down a | |
682 | * little, place the new task so that it fits in the slot that | |
683 | * stays open at the end. | |
684 | */ | |
685 | if (initial && sched_feat(START_DEBIT)) | |
686 | vruntime += sched_vslice_add(cfs_rq, se); | |
687 | ||
688 | if (!initial) { | |
689 | /* sleeps upto a single latency don't count. */ | |
690 | if (sched_feat(NEW_FAIR_SLEEPERS)) { | |
691 | unsigned long thresh = sysctl_sched_latency; | |
692 | ||
693 | /* | |
694 | * convert the sleeper threshold into virtual time | |
695 | */ | |
696 | if (sched_feat(NORMALIZED_SLEEPER)) | |
697 | thresh = calc_delta_fair(thresh, se); | |
698 | ||
699 | vruntime -= thresh; | |
700 | } | |
701 | ||
702 | /* ensure we never gain time by being placed backwards. */ | |
703 | vruntime = max_vruntime(se->vruntime, vruntime); | |
704 | } | |
705 | ||
706 | se->vruntime = vruntime; | |
707 | } | |
708 | ||
709 | static void | |
710 | enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup) | |
711 | { | |
712 | /* | |
713 | * Update run-time statistics of the 'current'. | |
714 | */ | |
715 | update_curr(cfs_rq); | |
716 | account_entity_enqueue(cfs_rq, se); | |
717 | ||
718 | if (wakeup) { | |
719 | place_entity(cfs_rq, se, 0); | |
720 | enqueue_sleeper(cfs_rq, se); | |
721 | } | |
722 | ||
723 | update_stats_enqueue(cfs_rq, se); | |
724 | check_spread(cfs_rq, se); | |
725 | if (se != cfs_rq->curr) | |
726 | __enqueue_entity(cfs_rq, se); | |
727 | } | |
728 | ||
729 | static void | |
730 | dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep) | |
731 | { | |
732 | /* | |
733 | * Update run-time statistics of the 'current'. | |
734 | */ | |
735 | update_curr(cfs_rq); | |
736 | ||
737 | update_stats_dequeue(cfs_rq, se); | |
738 | if (sleep) { | |
739 | #ifdef CONFIG_SCHEDSTATS | |
740 | if (entity_is_task(se)) { | |
741 | struct task_struct *tsk = task_of(se); | |
742 | ||
743 | if (tsk->state & TASK_INTERRUPTIBLE) | |
744 | se->sleep_start = rq_of(cfs_rq)->clock; | |
745 | if (tsk->state & TASK_UNINTERRUPTIBLE) | |
746 | se->block_start = rq_of(cfs_rq)->clock; | |
747 | } | |
748 | #endif | |
749 | } | |
750 | ||
751 | if (se != cfs_rq->curr) | |
752 | __dequeue_entity(cfs_rq, se); | |
753 | account_entity_dequeue(cfs_rq, se); | |
754 | } | |
755 | ||
756 | /* | |
757 | * Preempt the current task with a newly woken task if needed: | |
758 | */ | |
759 | static void | |
760 | check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) | |
761 | { | |
762 | unsigned long ideal_runtime, delta_exec; | |
763 | ||
764 | ideal_runtime = sched_slice(cfs_rq, curr); | |
765 | delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; | |
766 | if (delta_exec > ideal_runtime) | |
767 | resched_task(rq_of(cfs_rq)->curr); | |
768 | } | |
769 | ||
770 | static void | |
771 | set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
772 | { | |
773 | /* 'current' is not kept within the tree. */ | |
774 | if (se->on_rq) { | |
775 | /* | |
776 | * Any task has to be enqueued before it get to execute on | |
777 | * a CPU. So account for the time it spent waiting on the | |
778 | * runqueue. | |
779 | */ | |
780 | update_stats_wait_end(cfs_rq, se); | |
781 | __dequeue_entity(cfs_rq, se); | |
782 | } | |
783 | ||
784 | update_stats_curr_start(cfs_rq, se); | |
785 | cfs_rq->curr = se; | |
786 | #ifdef CONFIG_SCHEDSTATS | |
787 | /* | |
788 | * Track our maximum slice length, if the CPU's load is at | |
789 | * least twice that of our own weight (i.e. dont track it | |
790 | * when there are only lesser-weight tasks around): | |
791 | */ | |
792 | if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) { | |
793 | se->slice_max = max(se->slice_max, | |
794 | se->sum_exec_runtime - se->prev_sum_exec_runtime); | |
795 | } | |
796 | #endif | |
797 | se->prev_sum_exec_runtime = se->sum_exec_runtime; | |
798 | } | |
799 | ||
800 | static struct sched_entity * | |
801 | pick_next(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
802 | { | |
803 | struct rq *rq = rq_of(cfs_rq); | |
804 | u64 pair_slice = rq->clock - cfs_rq->pair_start; | |
805 | ||
806 | if (!cfs_rq->next || pair_slice > sched_slice(cfs_rq, cfs_rq->next)) { | |
807 | cfs_rq->pair_start = rq->clock; | |
808 | return se; | |
809 | } | |
810 | ||
811 | return cfs_rq->next; | |
812 | } | |
813 | ||
814 | static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) | |
815 | { | |
816 | struct sched_entity *se = NULL; | |
817 | ||
818 | if (first_fair(cfs_rq)) { | |
819 | se = __pick_next_entity(cfs_rq); | |
820 | se = pick_next(cfs_rq, se); | |
821 | set_next_entity(cfs_rq, se); | |
822 | } | |
823 | ||
824 | return se; | |
825 | } | |
826 | ||
827 | static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) | |
828 | { | |
829 | /* | |
830 | * If still on the runqueue then deactivate_task() | |
831 | * was not called and update_curr() has to be done: | |
832 | */ | |
833 | if (prev->on_rq) | |
834 | update_curr(cfs_rq); | |
835 | ||
836 | check_spread(cfs_rq, prev); | |
837 | if (prev->on_rq) { | |
838 | update_stats_wait_start(cfs_rq, prev); | |
839 | /* Put 'current' back into the tree. */ | |
840 | __enqueue_entity(cfs_rq, prev); | |
841 | } | |
842 | cfs_rq->curr = NULL; | |
843 | } | |
844 | ||
845 | static void | |
846 | entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) | |
847 | { | |
848 | /* | |
849 | * Update run-time statistics of the 'current'. | |
850 | */ | |
851 | update_curr(cfs_rq); | |
852 | ||
853 | #ifdef CONFIG_SCHED_HRTICK | |
854 | /* | |
855 | * queued ticks are scheduled to match the slice, so don't bother | |
856 | * validating it and just reschedule. | |
857 | */ | |
858 | if (queued) { | |
859 | resched_task(rq_of(cfs_rq)->curr); | |
860 | return; | |
861 | } | |
862 | /* | |
863 | * don't let the period tick interfere with the hrtick preemption | |
864 | */ | |
865 | if (!sched_feat(DOUBLE_TICK) && | |
866 | hrtimer_active(&rq_of(cfs_rq)->hrtick_timer)) | |
867 | return; | |
868 | #endif | |
869 | ||
870 | if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT)) | |
871 | check_preempt_tick(cfs_rq, curr); | |
872 | } | |
873 | ||
874 | /************************************************** | |
875 | * CFS operations on tasks: | |
876 | */ | |
877 | ||
878 | #ifdef CONFIG_SCHED_HRTICK | |
879 | static void hrtick_start_fair(struct rq *rq, struct task_struct *p) | |
880 | { | |
881 | int requeue = rq->curr == p; | |
882 | struct sched_entity *se = &p->se; | |
883 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
884 | ||
885 | WARN_ON(task_rq(p) != rq); | |
886 | ||
887 | if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) { | |
888 | u64 slice = sched_slice(cfs_rq, se); | |
889 | u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime; | |
890 | s64 delta = slice - ran; | |
891 | ||
892 | if (delta < 0) { | |
893 | if (rq->curr == p) | |
894 | resched_task(p); | |
895 | return; | |
896 | } | |
897 | ||
898 | /* | |
899 | * Don't schedule slices shorter than 10000ns, that just | |
900 | * doesn't make sense. Rely on vruntime for fairness. | |
901 | */ | |
902 | if (!requeue) | |
903 | delta = max(10000LL, delta); | |
904 | ||
905 | hrtick_start(rq, delta, requeue); | |
906 | } | |
907 | } | |
908 | #else /* !CONFIG_SCHED_HRTICK */ | |
909 | static inline void | |
910 | hrtick_start_fair(struct rq *rq, struct task_struct *p) | |
911 | { | |
912 | } | |
913 | #endif | |
914 | ||
915 | /* | |
916 | * The enqueue_task method is called before nr_running is | |
917 | * increased. Here we update the fair scheduling stats and | |
918 | * then put the task into the rbtree: | |
919 | */ | |
920 | static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup) | |
921 | { | |
922 | struct cfs_rq *cfs_rq; | |
923 | struct sched_entity *se = &p->se; | |
924 | ||
925 | for_each_sched_entity(se) { | |
926 | if (se->on_rq) | |
927 | break; | |
928 | cfs_rq = cfs_rq_of(se); | |
929 | enqueue_entity(cfs_rq, se, wakeup); | |
930 | wakeup = 1; | |
931 | } | |
932 | ||
933 | hrtick_start_fair(rq, rq->curr); | |
934 | } | |
935 | ||
936 | /* | |
937 | * The dequeue_task method is called before nr_running is | |
938 | * decreased. We remove the task from the rbtree and | |
939 | * update the fair scheduling stats: | |
940 | */ | |
941 | static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep) | |
942 | { | |
943 | struct cfs_rq *cfs_rq; | |
944 | struct sched_entity *se = &p->se; | |
945 | ||
946 | for_each_sched_entity(se) { | |
947 | cfs_rq = cfs_rq_of(se); | |
948 | dequeue_entity(cfs_rq, se, sleep); | |
949 | /* Don't dequeue parent if it has other entities besides us */ | |
950 | if (cfs_rq->load.weight) | |
951 | break; | |
952 | sleep = 1; | |
953 | } | |
954 | ||
955 | hrtick_start_fair(rq, rq->curr); | |
956 | } | |
957 | ||
958 | /* | |
959 | * sched_yield() support is very simple - we dequeue and enqueue. | |
960 | * | |
961 | * If compat_yield is turned on then we requeue to the end of the tree. | |
962 | */ | |
963 | static void yield_task_fair(struct rq *rq) | |
964 | { | |
965 | struct task_struct *curr = rq->curr; | |
966 | struct cfs_rq *cfs_rq = task_cfs_rq(curr); | |
967 | struct sched_entity *rightmost, *se = &curr->se; | |
968 | ||
969 | /* | |
970 | * Are we the only task in the tree? | |
971 | */ | |
972 | if (unlikely(cfs_rq->nr_running == 1)) | |
973 | return; | |
974 | ||
975 | if (likely(!sysctl_sched_compat_yield) && curr->policy != SCHED_BATCH) { | |
976 | update_rq_clock(rq); | |
977 | /* | |
978 | * Update run-time statistics of the 'current'. | |
979 | */ | |
980 | update_curr(cfs_rq); | |
981 | ||
982 | return; | |
983 | } | |
984 | /* | |
985 | * Find the rightmost entry in the rbtree: | |
986 | */ | |
987 | rightmost = __pick_last_entity(cfs_rq); | |
988 | /* | |
989 | * Already in the rightmost position? | |
990 | */ | |
991 | if (unlikely(!rightmost || rightmost->vruntime < se->vruntime)) | |
992 | return; | |
993 | ||
994 | /* | |
995 | * Minimally necessary key value to be last in the tree: | |
996 | * Upon rescheduling, sched_class::put_prev_task() will place | |
997 | * 'current' within the tree based on its new key value. | |
998 | */ | |
999 | se->vruntime = rightmost->vruntime + 1; | |
1000 | } | |
1001 | ||
1002 | /* | |
1003 | * wake_idle() will wake a task on an idle cpu if task->cpu is | |
1004 | * not idle and an idle cpu is available. The span of cpus to | |
1005 | * search starts with cpus closest then further out as needed, | |
1006 | * so we always favor a closer, idle cpu. | |
1007 | * | |
1008 | * Returns the CPU we should wake onto. | |
1009 | */ | |
1010 | #if defined(ARCH_HAS_SCHED_WAKE_IDLE) | |
1011 | static int wake_idle(int cpu, struct task_struct *p) | |
1012 | { | |
1013 | cpumask_t tmp; | |
1014 | struct sched_domain *sd; | |
1015 | int i; | |
1016 | ||
1017 | /* | |
1018 | * If it is idle, then it is the best cpu to run this task. | |
1019 | * | |
1020 | * This cpu is also the best, if it has more than one task already. | |
1021 | * Siblings must be also busy(in most cases) as they didn't already | |
1022 | * pickup the extra load from this cpu and hence we need not check | |
1023 | * sibling runqueue info. This will avoid the checks and cache miss | |
1024 | * penalities associated with that. | |
1025 | */ | |
1026 | if (idle_cpu(cpu) || cpu_rq(cpu)->cfs.nr_running > 1) | |
1027 | return cpu; | |
1028 | ||
1029 | for_each_domain(cpu, sd) { | |
1030 | if ((sd->flags & SD_WAKE_IDLE) | |
1031 | || ((sd->flags & SD_WAKE_IDLE_FAR) | |
1032 | && !task_hot(p, task_rq(p)->clock, sd))) { | |
1033 | cpus_and(tmp, sd->span, p->cpus_allowed); | |
1034 | for_each_cpu_mask(i, tmp) { | |
1035 | if (idle_cpu(i)) { | |
1036 | if (i != task_cpu(p)) { | |
1037 | schedstat_inc(p, | |
1038 | se.nr_wakeups_idle); | |
1039 | } | |
1040 | return i; | |
1041 | } | |
1042 | } | |
1043 | } else { | |
1044 | break; | |
1045 | } | |
1046 | } | |
1047 | return cpu; | |
1048 | } | |
1049 | #else /* !ARCH_HAS_SCHED_WAKE_IDLE*/ | |
1050 | static inline int wake_idle(int cpu, struct task_struct *p) | |
1051 | { | |
1052 | return cpu; | |
1053 | } | |
1054 | #endif | |
1055 | ||
1056 | #ifdef CONFIG_SMP | |
1057 | ||
1058 | static const struct sched_class fair_sched_class; | |
1059 | ||
1060 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
1061 | /* | |
1062 | * effective_load() calculates the load change as seen from the root_task_group | |
1063 | * | |
1064 | * Adding load to a group doesn't make a group heavier, but can cause movement | |
1065 | * of group shares between cpus. Assuming the shares were perfectly aligned one | |
1066 | * can calculate the shift in shares. | |
1067 | * | |
1068 | * The problem is that perfectly aligning the shares is rather expensive, hence | |
1069 | * we try to avoid doing that too often - see update_shares(), which ratelimits | |
1070 | * this change. | |
1071 | * | |
1072 | * We compensate this by not only taking the current delta into account, but | |
1073 | * also considering the delta between when the shares were last adjusted and | |
1074 | * now. | |
1075 | * | |
1076 | * We still saw a performance dip, some tracing learned us that between | |
1077 | * cgroup:/ and cgroup:/foo balancing the number of affine wakeups increased | |
1078 | * significantly. Therefore try to bias the error in direction of failing | |
1079 | * the affine wakeup. | |
1080 | * | |
1081 | */ | |
1082 | static long effective_load(struct task_group *tg, int cpu, | |
1083 | long wl, long wg) | |
1084 | { | |
1085 | struct sched_entity *se = tg->se[cpu]; | |
1086 | long more_w; | |
1087 | ||
1088 | if (!tg->parent) | |
1089 | return wl; | |
1090 | ||
1091 | /* | |
1092 | * By not taking the decrease of shares on the other cpu into | |
1093 | * account our error leans towards reducing the affine wakeups. | |
1094 | */ | |
1095 | if (!wl && sched_feat(ASYM_EFF_LOAD)) | |
1096 | return wl; | |
1097 | ||
1098 | /* | |
1099 | * Instead of using this increment, also add the difference | |
1100 | * between when the shares were last updated and now. | |
1101 | */ | |
1102 | more_w = se->my_q->load.weight - se->my_q->rq_weight; | |
1103 | wl += more_w; | |
1104 | wg += more_w; | |
1105 | ||
1106 | for_each_sched_entity(se) { | |
1107 | #define D(n) (likely(n) ? (n) : 1) | |
1108 | ||
1109 | long S, rw, s, a, b; | |
1110 | ||
1111 | S = se->my_q->tg->shares; | |
1112 | s = se->my_q->shares; | |
1113 | rw = se->my_q->rq_weight; | |
1114 | ||
1115 | a = S*(rw + wl); | |
1116 | b = S*rw + s*wg; | |
1117 | ||
1118 | wl = s*(a-b)/D(b); | |
1119 | /* | |
1120 | * Assume the group is already running and will | |
1121 | * thus already be accounted for in the weight. | |
1122 | * | |
1123 | * That is, moving shares between CPUs, does not | |
1124 | * alter the group weight. | |
1125 | */ | |
1126 | wg = 0; | |
1127 | #undef D | |
1128 | } | |
1129 | ||
1130 | return wl; | |
1131 | } | |
1132 | ||
1133 | #else | |
1134 | ||
1135 | static inline unsigned long effective_load(struct task_group *tg, int cpu, | |
1136 | unsigned long wl, unsigned long wg) | |
1137 | { | |
1138 | return wl; | |
1139 | } | |
1140 | ||
1141 | #endif | |
1142 | ||
1143 | static int | |
1144 | wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq, | |
1145 | struct task_struct *p, int prev_cpu, int this_cpu, int sync, | |
1146 | int idx, unsigned long load, unsigned long this_load, | |
1147 | unsigned int imbalance) | |
1148 | { | |
1149 | struct task_struct *curr = this_rq->curr; | |
1150 | struct task_group *tg; | |
1151 | unsigned long tl = this_load; | |
1152 | unsigned long tl_per_task; | |
1153 | unsigned long weight; | |
1154 | int balanced; | |
1155 | ||
1156 | if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS)) | |
1157 | return 0; | |
1158 | ||
1159 | /* | |
1160 | * If sync wakeup then subtract the (maximum possible) | |
1161 | * effect of the currently running task from the load | |
1162 | * of the current CPU: | |
1163 | */ | |
1164 | if (sync) { | |
1165 | tg = task_group(current); | |
1166 | weight = current->se.load.weight; | |
1167 | ||
1168 | tl += effective_load(tg, this_cpu, -weight, -weight); | |
1169 | load += effective_load(tg, prev_cpu, 0, -weight); | |
1170 | } | |
1171 | ||
1172 | tg = task_group(p); | |
1173 | weight = p->se.load.weight; | |
1174 | ||
1175 | balanced = 100*(tl + effective_load(tg, this_cpu, weight, weight)) <= | |
1176 | imbalance*(load + effective_load(tg, prev_cpu, 0, weight)); | |
1177 | ||
1178 | /* | |
1179 | * If the currently running task will sleep within | |
1180 | * a reasonable amount of time then attract this newly | |
1181 | * woken task: | |
1182 | */ | |
1183 | if (sync && balanced) { | |
1184 | if (curr->se.avg_overlap < sysctl_sched_migration_cost && | |
1185 | p->se.avg_overlap < sysctl_sched_migration_cost) | |
1186 | return 1; | |
1187 | } | |
1188 | ||
1189 | schedstat_inc(p, se.nr_wakeups_affine_attempts); | |
1190 | tl_per_task = cpu_avg_load_per_task(this_cpu); | |
1191 | ||
1192 | if ((tl <= load && tl + target_load(prev_cpu, idx) <= tl_per_task) || | |
1193 | balanced) { | |
1194 | /* | |
1195 | * This domain has SD_WAKE_AFFINE and | |
1196 | * p is cache cold in this domain, and | |
1197 | * there is no bad imbalance. | |
1198 | */ | |
1199 | schedstat_inc(this_sd, ttwu_move_affine); | |
1200 | schedstat_inc(p, se.nr_wakeups_affine); | |
1201 | ||
1202 | return 1; | |
1203 | } | |
1204 | return 0; | |
1205 | } | |
1206 | ||
1207 | static int select_task_rq_fair(struct task_struct *p, int sync) | |
1208 | { | |
1209 | struct sched_domain *sd, *this_sd = NULL; | |
1210 | int prev_cpu, this_cpu, new_cpu; | |
1211 | unsigned long load, this_load; | |
1212 | struct rq *rq, *this_rq; | |
1213 | unsigned int imbalance; | |
1214 | int idx; | |
1215 | ||
1216 | prev_cpu = task_cpu(p); | |
1217 | rq = task_rq(p); | |
1218 | this_cpu = smp_processor_id(); | |
1219 | this_rq = cpu_rq(this_cpu); | |
1220 | new_cpu = prev_cpu; | |
1221 | ||
1222 | /* | |
1223 | * 'this_sd' is the first domain that both | |
1224 | * this_cpu and prev_cpu are present in: | |
1225 | */ | |
1226 | for_each_domain(this_cpu, sd) { | |
1227 | if (cpu_isset(prev_cpu, sd->span)) { | |
1228 | this_sd = sd; | |
1229 | break; | |
1230 | } | |
1231 | } | |
1232 | ||
1233 | if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed))) | |
1234 | goto out; | |
1235 | ||
1236 | /* | |
1237 | * Check for affine wakeup and passive balancing possibilities. | |
1238 | */ | |
1239 | if (!this_sd) | |
1240 | goto out; | |
1241 | ||
1242 | idx = this_sd->wake_idx; | |
1243 | ||
1244 | imbalance = 100 + (this_sd->imbalance_pct - 100) / 2; | |
1245 | ||
1246 | load = source_load(prev_cpu, idx); | |
1247 | this_load = target_load(this_cpu, idx); | |
1248 | ||
1249 | if (wake_affine(rq, this_sd, this_rq, p, prev_cpu, this_cpu, sync, idx, | |
1250 | load, this_load, imbalance)) | |
1251 | return this_cpu; | |
1252 | ||
1253 | if (prev_cpu == this_cpu) | |
1254 | goto out; | |
1255 | ||
1256 | /* | |
1257 | * Start passive balancing when half the imbalance_pct | |
1258 | * limit is reached. | |
1259 | */ | |
1260 | if (this_sd->flags & SD_WAKE_BALANCE) { | |
1261 | if (imbalance*this_load <= 100*load) { | |
1262 | schedstat_inc(this_sd, ttwu_move_balance); | |
1263 | schedstat_inc(p, se.nr_wakeups_passive); | |
1264 | return this_cpu; | |
1265 | } | |
1266 | } | |
1267 | ||
1268 | out: | |
1269 | return wake_idle(new_cpu, p); | |
1270 | } | |
1271 | #endif /* CONFIG_SMP */ | |
1272 | ||
1273 | static unsigned long wakeup_gran(struct sched_entity *se) | |
1274 | { | |
1275 | unsigned long gran = sysctl_sched_wakeup_granularity; | |
1276 | ||
1277 | /* | |
1278 | * More easily preempt - nice tasks, while not making it harder for | |
1279 | * + nice tasks. | |
1280 | */ | |
1281 | if (sched_feat(ASYM_GRAN)) | |
1282 | gran = calc_delta_asym(sysctl_sched_wakeup_granularity, se); | |
1283 | else | |
1284 | gran = calc_delta_fair(sysctl_sched_wakeup_granularity, se); | |
1285 | ||
1286 | return gran; | |
1287 | } | |
1288 | ||
1289 | /* | |
1290 | * Should 'se' preempt 'curr'. | |
1291 | * | |
1292 | * |s1 | |
1293 | * |s2 | |
1294 | * |s3 | |
1295 | * g | |
1296 | * |<--->|c | |
1297 | * | |
1298 | * w(c, s1) = -1 | |
1299 | * w(c, s2) = 0 | |
1300 | * w(c, s3) = 1 | |
1301 | * | |
1302 | */ | |
1303 | static int | |
1304 | wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se) | |
1305 | { | |
1306 | s64 gran, vdiff = curr->vruntime - se->vruntime; | |
1307 | ||
1308 | if (vdiff < 0) | |
1309 | return -1; | |
1310 | ||
1311 | gran = wakeup_gran(curr); | |
1312 | if (vdiff > gran) | |
1313 | return 1; | |
1314 | ||
1315 | return 0; | |
1316 | } | |
1317 | ||
1318 | /* return depth at which a sched entity is present in the hierarchy */ | |
1319 | static inline int depth_se(struct sched_entity *se) | |
1320 | { | |
1321 | int depth = 0; | |
1322 | ||
1323 | for_each_sched_entity(se) | |
1324 | depth++; | |
1325 | ||
1326 | return depth; | |
1327 | } | |
1328 | ||
1329 | /* | |
1330 | * Preempt the current task with a newly woken task if needed: | |
1331 | */ | |
1332 | static void check_preempt_wakeup(struct rq *rq, struct task_struct *p) | |
1333 | { | |
1334 | struct task_struct *curr = rq->curr; | |
1335 | struct cfs_rq *cfs_rq = task_cfs_rq(curr); | |
1336 | struct sched_entity *se = &curr->se, *pse = &p->se; | |
1337 | int se_depth, pse_depth; | |
1338 | ||
1339 | if (unlikely(rt_prio(p->prio))) { | |
1340 | update_rq_clock(rq); | |
1341 | update_curr(cfs_rq); | |
1342 | resched_task(curr); | |
1343 | return; | |
1344 | } | |
1345 | ||
1346 | if (unlikely(se == pse)) | |
1347 | return; | |
1348 | ||
1349 | cfs_rq_of(pse)->next = pse; | |
1350 | ||
1351 | /* | |
1352 | * Batch tasks do not preempt (their preemption is driven by | |
1353 | * the tick): | |
1354 | */ | |
1355 | if (unlikely(p->policy == SCHED_BATCH)) | |
1356 | return; | |
1357 | ||
1358 | if (!sched_feat(WAKEUP_PREEMPT)) | |
1359 | return; | |
1360 | ||
1361 | /* | |
1362 | * preemption test can be made between sibling entities who are in the | |
1363 | * same cfs_rq i.e who have a common parent. Walk up the hierarchy of | |
1364 | * both tasks until we find their ancestors who are siblings of common | |
1365 | * parent. | |
1366 | */ | |
1367 | ||
1368 | /* First walk up until both entities are at same depth */ | |
1369 | se_depth = depth_se(se); | |
1370 | pse_depth = depth_se(pse); | |
1371 | ||
1372 | while (se_depth > pse_depth) { | |
1373 | se_depth--; | |
1374 | se = parent_entity(se); | |
1375 | } | |
1376 | ||
1377 | while (pse_depth > se_depth) { | |
1378 | pse_depth--; | |
1379 | pse = parent_entity(pse); | |
1380 | } | |
1381 | ||
1382 | while (!is_same_group(se, pse)) { | |
1383 | se = parent_entity(se); | |
1384 | pse = parent_entity(pse); | |
1385 | } | |
1386 | ||
1387 | if (wakeup_preempt_entity(se, pse) == 1) | |
1388 | resched_task(curr); | |
1389 | } | |
1390 | ||
1391 | static struct task_struct *pick_next_task_fair(struct rq *rq) | |
1392 | { | |
1393 | struct task_struct *p; | |
1394 | struct cfs_rq *cfs_rq = &rq->cfs; | |
1395 | struct sched_entity *se; | |
1396 | ||
1397 | if (unlikely(!cfs_rq->nr_running)) | |
1398 | return NULL; | |
1399 | ||
1400 | do { | |
1401 | se = pick_next_entity(cfs_rq); | |
1402 | cfs_rq = group_cfs_rq(se); | |
1403 | } while (cfs_rq); | |
1404 | ||
1405 | p = task_of(se); | |
1406 | hrtick_start_fair(rq, p); | |
1407 | ||
1408 | return p; | |
1409 | } | |
1410 | ||
1411 | /* | |
1412 | * Account for a descheduled task: | |
1413 | */ | |
1414 | static void put_prev_task_fair(struct rq *rq, struct task_struct *prev) | |
1415 | { | |
1416 | struct sched_entity *se = &prev->se; | |
1417 | struct cfs_rq *cfs_rq; | |
1418 | ||
1419 | for_each_sched_entity(se) { | |
1420 | cfs_rq = cfs_rq_of(se); | |
1421 | put_prev_entity(cfs_rq, se); | |
1422 | } | |
1423 | } | |
1424 | ||
1425 | #ifdef CONFIG_SMP | |
1426 | /************************************************** | |
1427 | * Fair scheduling class load-balancing methods: | |
1428 | */ | |
1429 | ||
1430 | /* | |
1431 | * Load-balancing iterator. Note: while the runqueue stays locked | |
1432 | * during the whole iteration, the current task might be | |
1433 | * dequeued so the iterator has to be dequeue-safe. Here we | |
1434 | * achieve that by always pre-iterating before returning | |
1435 | * the current task: | |
1436 | */ | |
1437 | static struct task_struct * | |
1438 | __load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next) | |
1439 | { | |
1440 | struct task_struct *p = NULL; | |
1441 | struct sched_entity *se; | |
1442 | ||
1443 | while (next != &cfs_rq->tasks) { | |
1444 | se = list_entry(next, struct sched_entity, group_node); | |
1445 | next = next->next; | |
1446 | ||
1447 | /* Skip over entities that are not tasks */ | |
1448 | if (entity_is_task(se)) { | |
1449 | p = task_of(se); | |
1450 | break; | |
1451 | } | |
1452 | } | |
1453 | ||
1454 | cfs_rq->balance_iterator = next; | |
1455 | return p; | |
1456 | } | |
1457 | ||
1458 | static struct task_struct *load_balance_start_fair(void *arg) | |
1459 | { | |
1460 | struct cfs_rq *cfs_rq = arg; | |
1461 | ||
1462 | return __load_balance_iterator(cfs_rq, cfs_rq->tasks.next); | |
1463 | } | |
1464 | ||
1465 | static struct task_struct *load_balance_next_fair(void *arg) | |
1466 | { | |
1467 | struct cfs_rq *cfs_rq = arg; | |
1468 | ||
1469 | return __load_balance_iterator(cfs_rq, cfs_rq->balance_iterator); | |
1470 | } | |
1471 | ||
1472 | static unsigned long | |
1473 | __load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, | |
1474 | unsigned long max_load_move, struct sched_domain *sd, | |
1475 | enum cpu_idle_type idle, int *all_pinned, int *this_best_prio, | |
1476 | struct cfs_rq *cfs_rq) | |
1477 | { | |
1478 | struct rq_iterator cfs_rq_iterator; | |
1479 | ||
1480 | cfs_rq_iterator.start = load_balance_start_fair; | |
1481 | cfs_rq_iterator.next = load_balance_next_fair; | |
1482 | cfs_rq_iterator.arg = cfs_rq; | |
1483 | ||
1484 | return balance_tasks(this_rq, this_cpu, busiest, | |
1485 | max_load_move, sd, idle, all_pinned, | |
1486 | this_best_prio, &cfs_rq_iterator); | |
1487 | } | |
1488 | ||
1489 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
1490 | static unsigned long | |
1491 | load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, | |
1492 | unsigned long max_load_move, | |
1493 | struct sched_domain *sd, enum cpu_idle_type idle, | |
1494 | int *all_pinned, int *this_best_prio) | |
1495 | { | |
1496 | long rem_load_move = max_load_move; | |
1497 | int busiest_cpu = cpu_of(busiest); | |
1498 | struct task_group *tg; | |
1499 | ||
1500 | rcu_read_lock(); | |
1501 | update_h_load(busiest_cpu); | |
1502 | ||
1503 | list_for_each_entry(tg, &task_groups, list) { | |
1504 | struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu]; | |
1505 | unsigned long busiest_h_load = busiest_cfs_rq->h_load; | |
1506 | unsigned long busiest_weight = busiest_cfs_rq->load.weight; | |
1507 | u64 rem_load, moved_load; | |
1508 | ||
1509 | /* | |
1510 | * empty group | |
1511 | */ | |
1512 | if (!busiest_cfs_rq->task_weight) | |
1513 | continue; | |
1514 | ||
1515 | rem_load = (u64)rem_load_move * busiest_weight; | |
1516 | rem_load = div_u64(rem_load, busiest_h_load + 1); | |
1517 | ||
1518 | moved_load = __load_balance_fair(this_rq, this_cpu, busiest, | |
1519 | rem_load, sd, idle, all_pinned, this_best_prio, | |
1520 | tg->cfs_rq[busiest_cpu]); | |
1521 | ||
1522 | if (!moved_load) | |
1523 | continue; | |
1524 | ||
1525 | moved_load *= busiest_h_load; | |
1526 | moved_load = div_u64(moved_load, busiest_weight + 1); | |
1527 | ||
1528 | rem_load_move -= moved_load; | |
1529 | if (rem_load_move < 0) | |
1530 | break; | |
1531 | } | |
1532 | rcu_read_unlock(); | |
1533 | ||
1534 | return max_load_move - rem_load_move; | |
1535 | } | |
1536 | #else | |
1537 | static unsigned long | |
1538 | load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, | |
1539 | unsigned long max_load_move, | |
1540 | struct sched_domain *sd, enum cpu_idle_type idle, | |
1541 | int *all_pinned, int *this_best_prio) | |
1542 | { | |
1543 | return __load_balance_fair(this_rq, this_cpu, busiest, | |
1544 | max_load_move, sd, idle, all_pinned, | |
1545 | this_best_prio, &busiest->cfs); | |
1546 | } | |
1547 | #endif | |
1548 | ||
1549 | static int | |
1550 | move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, | |
1551 | struct sched_domain *sd, enum cpu_idle_type idle) | |
1552 | { | |
1553 | struct cfs_rq *busy_cfs_rq; | |
1554 | struct rq_iterator cfs_rq_iterator; | |
1555 | ||
1556 | cfs_rq_iterator.start = load_balance_start_fair; | |
1557 | cfs_rq_iterator.next = load_balance_next_fair; | |
1558 | ||
1559 | for_each_leaf_cfs_rq(busiest, busy_cfs_rq) { | |
1560 | /* | |
1561 | * pass busy_cfs_rq argument into | |
1562 | * load_balance_[start|next]_fair iterators | |
1563 | */ | |
1564 | cfs_rq_iterator.arg = busy_cfs_rq; | |
1565 | if (iter_move_one_task(this_rq, this_cpu, busiest, sd, idle, | |
1566 | &cfs_rq_iterator)) | |
1567 | return 1; | |
1568 | } | |
1569 | ||
1570 | return 0; | |
1571 | } | |
1572 | #endif /* CONFIG_SMP */ | |
1573 | ||
1574 | /* | |
1575 | * scheduler tick hitting a task of our scheduling class: | |
1576 | */ | |
1577 | static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) | |
1578 | { | |
1579 | struct cfs_rq *cfs_rq; | |
1580 | struct sched_entity *se = &curr->se; | |
1581 | ||
1582 | for_each_sched_entity(se) { | |
1583 | cfs_rq = cfs_rq_of(se); | |
1584 | entity_tick(cfs_rq, se, queued); | |
1585 | } | |
1586 | } | |
1587 | ||
1588 | #define swap(a, b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0) | |
1589 | ||
1590 | /* | |
1591 | * Share the fairness runtime between parent and child, thus the | |
1592 | * total amount of pressure for CPU stays equal - new tasks | |
1593 | * get a chance to run but frequent forkers are not allowed to | |
1594 | * monopolize the CPU. Note: the parent runqueue is locked, | |
1595 | * the child is not running yet. | |
1596 | */ | |
1597 | static void task_new_fair(struct rq *rq, struct task_struct *p) | |
1598 | { | |
1599 | struct cfs_rq *cfs_rq = task_cfs_rq(p); | |
1600 | struct sched_entity *se = &p->se, *curr = cfs_rq->curr; | |
1601 | int this_cpu = smp_processor_id(); | |
1602 | ||
1603 | sched_info_queued(p); | |
1604 | ||
1605 | update_curr(cfs_rq); | |
1606 | place_entity(cfs_rq, se, 1); | |
1607 | ||
1608 | /* 'curr' will be NULL if the child belongs to a different group */ | |
1609 | if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) && | |
1610 | curr && curr->vruntime < se->vruntime) { | |
1611 | /* | |
1612 | * Upon rescheduling, sched_class::put_prev_task() will place | |
1613 | * 'current' within the tree based on its new key value. | |
1614 | */ | |
1615 | swap(curr->vruntime, se->vruntime); | |
1616 | } | |
1617 | ||
1618 | enqueue_task_fair(rq, p, 0); | |
1619 | resched_task(rq->curr); | |
1620 | } | |
1621 | ||
1622 | /* | |
1623 | * Priority of the task has changed. Check to see if we preempt | |
1624 | * the current task. | |
1625 | */ | |
1626 | static void prio_changed_fair(struct rq *rq, struct task_struct *p, | |
1627 | int oldprio, int running) | |
1628 | { | |
1629 | /* | |
1630 | * Reschedule if we are currently running on this runqueue and | |
1631 | * our priority decreased, or if we are not currently running on | |
1632 | * this runqueue and our priority is higher than the current's | |
1633 | */ | |
1634 | if (running) { | |
1635 | if (p->prio > oldprio) | |
1636 | resched_task(rq->curr); | |
1637 | } else | |
1638 | check_preempt_curr(rq, p); | |
1639 | } | |
1640 | ||
1641 | /* | |
1642 | * We switched to the sched_fair class. | |
1643 | */ | |
1644 | static void switched_to_fair(struct rq *rq, struct task_struct *p, | |
1645 | int running) | |
1646 | { | |
1647 | /* | |
1648 | * We were most likely switched from sched_rt, so | |
1649 | * kick off the schedule if running, otherwise just see | |
1650 | * if we can still preempt the current task. | |
1651 | */ | |
1652 | if (running) | |
1653 | resched_task(rq->curr); | |
1654 | else | |
1655 | check_preempt_curr(rq, p); | |
1656 | } | |
1657 | ||
1658 | /* Account for a task changing its policy or group. | |
1659 | * | |
1660 | * This routine is mostly called to set cfs_rq->curr field when a task | |
1661 | * migrates between groups/classes. | |
1662 | */ | |
1663 | static void set_curr_task_fair(struct rq *rq) | |
1664 | { | |
1665 | struct sched_entity *se = &rq->curr->se; | |
1666 | ||
1667 | for_each_sched_entity(se) | |
1668 | set_next_entity(cfs_rq_of(se), se); | |
1669 | } | |
1670 | ||
1671 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
1672 | static void moved_group_fair(struct task_struct *p) | |
1673 | { | |
1674 | struct cfs_rq *cfs_rq = task_cfs_rq(p); | |
1675 | ||
1676 | update_curr(cfs_rq); | |
1677 | place_entity(cfs_rq, &p->se, 1); | |
1678 | } | |
1679 | #endif | |
1680 | ||
1681 | /* | |
1682 | * All the scheduling class methods: | |
1683 | */ | |
1684 | static const struct sched_class fair_sched_class = { | |
1685 | .next = &idle_sched_class, | |
1686 | .enqueue_task = enqueue_task_fair, | |
1687 | .dequeue_task = dequeue_task_fair, | |
1688 | .yield_task = yield_task_fair, | |
1689 | #ifdef CONFIG_SMP | |
1690 | .select_task_rq = select_task_rq_fair, | |
1691 | #endif /* CONFIG_SMP */ | |
1692 | ||
1693 | .check_preempt_curr = check_preempt_wakeup, | |
1694 | ||
1695 | .pick_next_task = pick_next_task_fair, | |
1696 | .put_prev_task = put_prev_task_fair, | |
1697 | ||
1698 | #ifdef CONFIG_SMP | |
1699 | .load_balance = load_balance_fair, | |
1700 | .move_one_task = move_one_task_fair, | |
1701 | #endif | |
1702 | ||
1703 | .set_curr_task = set_curr_task_fair, | |
1704 | .task_tick = task_tick_fair, | |
1705 | .task_new = task_new_fair, | |
1706 | ||
1707 | .prio_changed = prio_changed_fair, | |
1708 | .switched_to = switched_to_fair, | |
1709 | ||
1710 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
1711 | .moved_group = moved_group_fair, | |
1712 | #endif | |
1713 | }; | |
1714 | ||
1715 | #ifdef CONFIG_SCHED_DEBUG | |
1716 | static void print_cfs_stats(struct seq_file *m, int cpu) | |
1717 | { | |
1718 | struct cfs_rq *cfs_rq; | |
1719 | ||
1720 | rcu_read_lock(); | |
1721 | for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) | |
1722 | print_cfs_rq(m, cpu, cfs_rq); | |
1723 | rcu_read_unlock(); | |
1724 | } | |
1725 | #endif |