Merge branch 'sony' into release
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / sched_fair.c
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 static const struct sched_class fair_sched_class;
77
78 /**************************************************************
79 * CFS operations on generic schedulable entities:
80 */
81
82 static inline struct task_struct *task_of(struct sched_entity *se)
83 {
84 return container_of(se, struct task_struct, se);
85 }
86
87 #ifdef CONFIG_FAIR_GROUP_SCHED
88
89 /* cpu runqueue to which this cfs_rq is attached */
90 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
91 {
92 return cfs_rq->rq;
93 }
94
95 /* An entity is a task if it doesn't "own" a runqueue */
96 #define entity_is_task(se) (!se->my_q)
97
98 /* Walk up scheduling entities hierarchy */
99 #define for_each_sched_entity(se) \
100 for (; se; se = se->parent)
101
102 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
103 {
104 return p->se.cfs_rq;
105 }
106
107 /* runqueue on which this entity is (to be) queued */
108 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
109 {
110 return se->cfs_rq;
111 }
112
113 /* runqueue "owned" by this group */
114 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
115 {
116 return grp->my_q;
117 }
118
119 /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on
120 * another cpu ('this_cpu')
121 */
122 static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
123 {
124 return cfs_rq->tg->cfs_rq[this_cpu];
125 }
126
127 /* Iterate thr' all leaf cfs_rq's on a runqueue */
128 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
129 list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
130
131 /* Do the two (enqueued) entities belong to the same group ? */
132 static inline int
133 is_same_group(struct sched_entity *se, struct sched_entity *pse)
134 {
135 if (se->cfs_rq == pse->cfs_rq)
136 return 1;
137
138 return 0;
139 }
140
141 static inline struct sched_entity *parent_entity(struct sched_entity *se)
142 {
143 return se->parent;
144 }
145
146 /* return depth at which a sched entity is present in the hierarchy */
147 static inline int depth_se(struct sched_entity *se)
148 {
149 int depth = 0;
150
151 for_each_sched_entity(se)
152 depth++;
153
154 return depth;
155 }
156
157 static void
158 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
159 {
160 int se_depth, pse_depth;
161
162 /*
163 * preemption test can be made between sibling entities who are in the
164 * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
165 * both tasks until we find their ancestors who are siblings of common
166 * parent.
167 */
168
169 /* First walk up until both entities are at same depth */
170 se_depth = depth_se(*se);
171 pse_depth = depth_se(*pse);
172
173 while (se_depth > pse_depth) {
174 se_depth--;
175 *se = parent_entity(*se);
176 }
177
178 while (pse_depth > se_depth) {
179 pse_depth--;
180 *pse = parent_entity(*pse);
181 }
182
183 while (!is_same_group(*se, *pse)) {
184 *se = parent_entity(*se);
185 *pse = parent_entity(*pse);
186 }
187 }
188
189 #else /* CONFIG_FAIR_GROUP_SCHED */
190
191 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
192 {
193 return container_of(cfs_rq, struct rq, cfs);
194 }
195
196 #define entity_is_task(se) 1
197
198 #define for_each_sched_entity(se) \
199 for (; se; se = NULL)
200
201 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
202 {
203 return &task_rq(p)->cfs;
204 }
205
206 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
207 {
208 struct task_struct *p = task_of(se);
209 struct rq *rq = task_rq(p);
210
211 return &rq->cfs;
212 }
213
214 /* runqueue "owned" by this group */
215 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
216 {
217 return NULL;
218 }
219
220 static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
221 {
222 return &cpu_rq(this_cpu)->cfs;
223 }
224
225 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
226 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
227
228 static inline int
229 is_same_group(struct sched_entity *se, struct sched_entity *pse)
230 {
231 return 1;
232 }
233
234 static inline struct sched_entity *parent_entity(struct sched_entity *se)
235 {
236 return NULL;
237 }
238
239 static inline void
240 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
241 {
242 }
243
244 #endif /* CONFIG_FAIR_GROUP_SCHED */
245
246
247 /**************************************************************
248 * Scheduling class tree data structure manipulation methods:
249 */
250
251 static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime)
252 {
253 s64 delta = (s64)(vruntime - min_vruntime);
254 if (delta > 0)
255 min_vruntime = vruntime;
256
257 return min_vruntime;
258 }
259
260 static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
261 {
262 s64 delta = (s64)(vruntime - min_vruntime);
263 if (delta < 0)
264 min_vruntime = vruntime;
265
266 return min_vruntime;
267 }
268
269 static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
270 {
271 return se->vruntime - cfs_rq->min_vruntime;
272 }
273
274 static void update_min_vruntime(struct cfs_rq *cfs_rq)
275 {
276 u64 vruntime = cfs_rq->min_vruntime;
277
278 if (cfs_rq->curr)
279 vruntime = cfs_rq->curr->vruntime;
280
281 if (cfs_rq->rb_leftmost) {
282 struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost,
283 struct sched_entity,
284 run_node);
285
286 if (vruntime == cfs_rq->min_vruntime)
287 vruntime = se->vruntime;
288 else
289 vruntime = min_vruntime(vruntime, se->vruntime);
290 }
291
292 cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
293 }
294
295 /*
296 * Enqueue an entity into the rb-tree:
297 */
298 static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
299 {
300 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
301 struct rb_node *parent = NULL;
302 struct sched_entity *entry;
303 s64 key = entity_key(cfs_rq, se);
304 int leftmost = 1;
305
306 /*
307 * Find the right place in the rbtree:
308 */
309 while (*link) {
310 parent = *link;
311 entry = rb_entry(parent, struct sched_entity, run_node);
312 /*
313 * We dont care about collisions. Nodes with
314 * the same key stay together.
315 */
316 if (key < entity_key(cfs_rq, entry)) {
317 link = &parent->rb_left;
318 } else {
319 link = &parent->rb_right;
320 leftmost = 0;
321 }
322 }
323
324 /*
325 * Maintain a cache of leftmost tree entries (it is frequently
326 * used):
327 */
328 if (leftmost)
329 cfs_rq->rb_leftmost = &se->run_node;
330
331 rb_link_node(&se->run_node, parent, link);
332 rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
333 }
334
335 static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
336 {
337 if (cfs_rq->rb_leftmost == &se->run_node) {
338 struct rb_node *next_node;
339
340 next_node = rb_next(&se->run_node);
341 cfs_rq->rb_leftmost = next_node;
342 }
343
344 rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
345 }
346
347 static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
348 {
349 struct rb_node *left = cfs_rq->rb_leftmost;
350
351 if (!left)
352 return NULL;
353
354 return rb_entry(left, struct sched_entity, run_node);
355 }
356
357 static struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
358 {
359 struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
360
361 if (!last)
362 return NULL;
363
364 return rb_entry(last, struct sched_entity, run_node);
365 }
366
367 /**************************************************************
368 * Scheduling class statistics methods:
369 */
370
371 #ifdef CONFIG_SCHED_DEBUG
372 int sched_nr_latency_handler(struct ctl_table *table, int write,
373 struct file *filp, void __user *buffer, size_t *lenp,
374 loff_t *ppos)
375 {
376 int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
377
378 if (ret || !write)
379 return ret;
380
381 sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
382 sysctl_sched_min_granularity);
383
384 return 0;
385 }
386 #endif
387
388 /*
389 * delta *= P[w / rw]
390 */
391 static inline unsigned long
392 calc_delta_weight(unsigned long delta, struct sched_entity *se)
393 {
394 for_each_sched_entity(se) {
395 delta = calc_delta_mine(delta,
396 se->load.weight, &cfs_rq_of(se)->load);
397 }
398
399 return delta;
400 }
401
402 /*
403 * delta /= w
404 */
405 static inline unsigned long
406 calc_delta_fair(unsigned long delta, struct sched_entity *se)
407 {
408 if (unlikely(se->load.weight != NICE_0_LOAD))
409 delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load);
410
411 return delta;
412 }
413
414 /*
415 * The idea is to set a period in which each task runs once.
416 *
417 * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
418 * this period because otherwise the slices get too small.
419 *
420 * p = (nr <= nl) ? l : l*nr/nl
421 */
422 static u64 __sched_period(unsigned long nr_running)
423 {
424 u64 period = sysctl_sched_latency;
425 unsigned long nr_latency = sched_nr_latency;
426
427 if (unlikely(nr_running > nr_latency)) {
428 period = sysctl_sched_min_granularity;
429 period *= nr_running;
430 }
431
432 return period;
433 }
434
435 /*
436 * We calculate the wall-time slice from the period by taking a part
437 * proportional to the weight.
438 *
439 * s = p*P[w/rw]
440 */
441 static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
442 {
443 unsigned long nr_running = cfs_rq->nr_running;
444
445 if (unlikely(!se->on_rq))
446 nr_running++;
447
448 return calc_delta_weight(__sched_period(nr_running), se);
449 }
450
451 /*
452 * We calculate the vruntime slice of a to be inserted task
453 *
454 * vs = s/w
455 */
456 static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
457 {
458 return calc_delta_fair(sched_slice(cfs_rq, se), se);
459 }
460
461 /*
462 * Update the current task's runtime statistics. Skip current tasks that
463 * are not in our scheduling class.
464 */
465 static inline void
466 __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
467 unsigned long delta_exec)
468 {
469 unsigned long delta_exec_weighted;
470
471 schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
472
473 curr->sum_exec_runtime += delta_exec;
474 schedstat_add(cfs_rq, exec_clock, delta_exec);
475 delta_exec_weighted = calc_delta_fair(delta_exec, curr);
476 curr->vruntime += delta_exec_weighted;
477 update_min_vruntime(cfs_rq);
478 }
479
480 static void update_curr(struct cfs_rq *cfs_rq)
481 {
482 struct sched_entity *curr = cfs_rq->curr;
483 u64 now = rq_of(cfs_rq)->clock;
484 unsigned long delta_exec;
485
486 if (unlikely(!curr))
487 return;
488
489 /*
490 * Get the amount of time the current task was running
491 * since the last time we changed load (this cannot
492 * overflow on 32 bits):
493 */
494 delta_exec = (unsigned long)(now - curr->exec_start);
495
496 __update_curr(cfs_rq, curr, delta_exec);
497 curr->exec_start = now;
498
499 if (entity_is_task(curr)) {
500 struct task_struct *curtask = task_of(curr);
501
502 cpuacct_charge(curtask, delta_exec);
503 account_group_exec_runtime(curtask, delta_exec);
504 }
505 }
506
507 static inline void
508 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
509 {
510 schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
511 }
512
513 /*
514 * Task is being enqueued - update stats:
515 */
516 static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
517 {
518 /*
519 * Are we enqueueing a waiting task? (for current tasks
520 * a dequeue/enqueue event is a NOP)
521 */
522 if (se != cfs_rq->curr)
523 update_stats_wait_start(cfs_rq, se);
524 }
525
526 static void
527 update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
528 {
529 schedstat_set(se->wait_max, max(se->wait_max,
530 rq_of(cfs_rq)->clock - se->wait_start));
531 schedstat_set(se->wait_count, se->wait_count + 1);
532 schedstat_set(se->wait_sum, se->wait_sum +
533 rq_of(cfs_rq)->clock - se->wait_start);
534 schedstat_set(se->wait_start, 0);
535 }
536
537 static inline void
538 update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
539 {
540 /*
541 * Mark the end of the wait period if dequeueing a
542 * waiting task:
543 */
544 if (se != cfs_rq->curr)
545 update_stats_wait_end(cfs_rq, se);
546 }
547
548 /*
549 * We are picking a new current task - update its stats:
550 */
551 static inline void
552 update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
553 {
554 /*
555 * We are starting a new run period:
556 */
557 se->exec_start = rq_of(cfs_rq)->clock;
558 }
559
560 /**************************************************
561 * Scheduling class queueing methods:
562 */
563
564 #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
565 static void
566 add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
567 {
568 cfs_rq->task_weight += weight;
569 }
570 #else
571 static inline void
572 add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
573 {
574 }
575 #endif
576
577 static void
578 account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
579 {
580 update_load_add(&cfs_rq->load, se->load.weight);
581 if (!parent_entity(se))
582 inc_cpu_load(rq_of(cfs_rq), se->load.weight);
583 if (entity_is_task(se)) {
584 add_cfs_task_weight(cfs_rq, se->load.weight);
585 list_add(&se->group_node, &cfs_rq->tasks);
586 }
587 cfs_rq->nr_running++;
588 se->on_rq = 1;
589 }
590
591 static void
592 account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
593 {
594 update_load_sub(&cfs_rq->load, se->load.weight);
595 if (!parent_entity(se))
596 dec_cpu_load(rq_of(cfs_rq), se->load.weight);
597 if (entity_is_task(se)) {
598 add_cfs_task_weight(cfs_rq, -se->load.weight);
599 list_del_init(&se->group_node);
600 }
601 cfs_rq->nr_running--;
602 se->on_rq = 0;
603 }
604
605 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
606 {
607 #ifdef CONFIG_SCHEDSTATS
608 if (se->sleep_start) {
609 u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
610 struct task_struct *tsk = task_of(se);
611
612 if ((s64)delta < 0)
613 delta = 0;
614
615 if (unlikely(delta > se->sleep_max))
616 se->sleep_max = delta;
617
618 se->sleep_start = 0;
619 se->sum_sleep_runtime += delta;
620
621 account_scheduler_latency(tsk, delta >> 10, 1);
622 }
623 if (se->block_start) {
624 u64 delta = rq_of(cfs_rq)->clock - se->block_start;
625 struct task_struct *tsk = task_of(se);
626
627 if ((s64)delta < 0)
628 delta = 0;
629
630 if (unlikely(delta > se->block_max))
631 se->block_max = delta;
632
633 se->block_start = 0;
634 se->sum_sleep_runtime += delta;
635
636 /*
637 * Blocking time is in units of nanosecs, so shift by 20 to
638 * get a milliseconds-range estimation of the amount of
639 * time that the task spent sleeping:
640 */
641 if (unlikely(prof_on == SLEEP_PROFILING)) {
642
643 profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
644 delta >> 20);
645 }
646 account_scheduler_latency(tsk, delta >> 10, 0);
647 }
648 #endif
649 }
650
651 static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
652 {
653 #ifdef CONFIG_SCHED_DEBUG
654 s64 d = se->vruntime - cfs_rq->min_vruntime;
655
656 if (d < 0)
657 d = -d;
658
659 if (d > 3*sysctl_sched_latency)
660 schedstat_inc(cfs_rq, nr_spread_over);
661 #endif
662 }
663
664 static void
665 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
666 {
667 u64 vruntime = cfs_rq->min_vruntime;
668
669 /*
670 * The 'current' period is already promised to the current tasks,
671 * however the extra weight of the new task will slow them down a
672 * little, place the new task so that it fits in the slot that
673 * stays open at the end.
674 */
675 if (initial && sched_feat(START_DEBIT))
676 vruntime += sched_vslice(cfs_rq, se);
677
678 if (!initial) {
679 /* sleeps upto a single latency don't count. */
680 if (sched_feat(NEW_FAIR_SLEEPERS)) {
681 unsigned long thresh = sysctl_sched_latency;
682
683 /*
684 * convert the sleeper threshold into virtual time
685 */
686 if (sched_feat(NORMALIZED_SLEEPER))
687 thresh = calc_delta_fair(thresh, se);
688
689 vruntime -= thresh;
690 }
691
692 /* ensure we never gain time by being placed backwards. */
693 vruntime = max_vruntime(se->vruntime, vruntime);
694 }
695
696 se->vruntime = vruntime;
697 }
698
699 static void
700 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
701 {
702 /*
703 * Update run-time statistics of the 'current'.
704 */
705 update_curr(cfs_rq);
706 account_entity_enqueue(cfs_rq, se);
707
708 if (wakeup) {
709 place_entity(cfs_rq, se, 0);
710 enqueue_sleeper(cfs_rq, se);
711 }
712
713 update_stats_enqueue(cfs_rq, se);
714 check_spread(cfs_rq, se);
715 if (se != cfs_rq->curr)
716 __enqueue_entity(cfs_rq, se);
717 }
718
719 static void
720 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
721 {
722 /*
723 * Update run-time statistics of the 'current'.
724 */
725 update_curr(cfs_rq);
726
727 update_stats_dequeue(cfs_rq, se);
728 if (sleep) {
729 #ifdef CONFIG_SCHEDSTATS
730 if (entity_is_task(se)) {
731 struct task_struct *tsk = task_of(se);
732
733 if (tsk->state & TASK_INTERRUPTIBLE)
734 se->sleep_start = rq_of(cfs_rq)->clock;
735 if (tsk->state & TASK_UNINTERRUPTIBLE)
736 se->block_start = rq_of(cfs_rq)->clock;
737 }
738 #endif
739 }
740
741 if (cfs_rq->last == se)
742 cfs_rq->last = NULL;
743
744 if (cfs_rq->next == se)
745 cfs_rq->next = NULL;
746
747 if (se != cfs_rq->curr)
748 __dequeue_entity(cfs_rq, se);
749 account_entity_dequeue(cfs_rq, se);
750 update_min_vruntime(cfs_rq);
751 }
752
753 /*
754 * Preempt the current task with a newly woken task if needed:
755 */
756 static void
757 check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
758 {
759 unsigned long ideal_runtime, delta_exec;
760
761 ideal_runtime = sched_slice(cfs_rq, curr);
762 delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
763 if (delta_exec > ideal_runtime)
764 resched_task(rq_of(cfs_rq)->curr);
765 }
766
767 static void
768 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
769 {
770 /* 'current' is not kept within the tree. */
771 if (se->on_rq) {
772 /*
773 * Any task has to be enqueued before it get to execute on
774 * a CPU. So account for the time it spent waiting on the
775 * runqueue.
776 */
777 update_stats_wait_end(cfs_rq, se);
778 __dequeue_entity(cfs_rq, se);
779 }
780
781 update_stats_curr_start(cfs_rq, se);
782 cfs_rq->curr = se;
783 #ifdef CONFIG_SCHEDSTATS
784 /*
785 * Track our maximum slice length, if the CPU's load is at
786 * least twice that of our own weight (i.e. dont track it
787 * when there are only lesser-weight tasks around):
788 */
789 if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
790 se->slice_max = max(se->slice_max,
791 se->sum_exec_runtime - se->prev_sum_exec_runtime);
792 }
793 #endif
794 se->prev_sum_exec_runtime = se->sum_exec_runtime;
795 }
796
797 static int
798 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
799
800 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
801 {
802 struct sched_entity *se = __pick_next_entity(cfs_rq);
803
804 if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, se) < 1)
805 return cfs_rq->next;
806
807 if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, se) < 1)
808 return cfs_rq->last;
809
810 return se;
811 }
812
813 static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
814 {
815 /*
816 * If still on the runqueue then deactivate_task()
817 * was not called and update_curr() has to be done:
818 */
819 if (prev->on_rq)
820 update_curr(cfs_rq);
821
822 check_spread(cfs_rq, prev);
823 if (prev->on_rq) {
824 update_stats_wait_start(cfs_rq, prev);
825 /* Put 'current' back into the tree. */
826 __enqueue_entity(cfs_rq, prev);
827 }
828 cfs_rq->curr = NULL;
829 }
830
831 static void
832 entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
833 {
834 /*
835 * Update run-time statistics of the 'current'.
836 */
837 update_curr(cfs_rq);
838
839 #ifdef CONFIG_SCHED_HRTICK
840 /*
841 * queued ticks are scheduled to match the slice, so don't bother
842 * validating it and just reschedule.
843 */
844 if (queued) {
845 resched_task(rq_of(cfs_rq)->curr);
846 return;
847 }
848 /*
849 * don't let the period tick interfere with the hrtick preemption
850 */
851 if (!sched_feat(DOUBLE_TICK) &&
852 hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
853 return;
854 #endif
855
856 if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
857 check_preempt_tick(cfs_rq, curr);
858 }
859
860 /**************************************************
861 * CFS operations on tasks:
862 */
863
864 #ifdef CONFIG_SCHED_HRTICK
865 static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
866 {
867 struct sched_entity *se = &p->se;
868 struct cfs_rq *cfs_rq = cfs_rq_of(se);
869
870 WARN_ON(task_rq(p) != rq);
871
872 if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) {
873 u64 slice = sched_slice(cfs_rq, se);
874 u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
875 s64 delta = slice - ran;
876
877 if (delta < 0) {
878 if (rq->curr == p)
879 resched_task(p);
880 return;
881 }
882
883 /*
884 * Don't schedule slices shorter than 10000ns, that just
885 * doesn't make sense. Rely on vruntime for fairness.
886 */
887 if (rq->curr != p)
888 delta = max_t(s64, 10000LL, delta);
889
890 hrtick_start(rq, delta);
891 }
892 }
893
894 /*
895 * called from enqueue/dequeue and updates the hrtick when the
896 * current task is from our class and nr_running is low enough
897 * to matter.
898 */
899 static void hrtick_update(struct rq *rq)
900 {
901 struct task_struct *curr = rq->curr;
902
903 if (curr->sched_class != &fair_sched_class)
904 return;
905
906 if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
907 hrtick_start_fair(rq, curr);
908 }
909 #else /* !CONFIG_SCHED_HRTICK */
910 static inline void
911 hrtick_start_fair(struct rq *rq, struct task_struct *p)
912 {
913 }
914
915 static inline void hrtick_update(struct rq *rq)
916 {
917 }
918 #endif
919
920 /*
921 * The enqueue_task method is called before nr_running is
922 * increased. Here we update the fair scheduling stats and
923 * then put the task into the rbtree:
924 */
925 static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
926 {
927 struct cfs_rq *cfs_rq;
928 struct sched_entity *se = &p->se;
929
930 for_each_sched_entity(se) {
931 if (se->on_rq)
932 break;
933 cfs_rq = cfs_rq_of(se);
934 enqueue_entity(cfs_rq, se, wakeup);
935 wakeup = 1;
936 }
937
938 hrtick_update(rq);
939 }
940
941 /*
942 * The dequeue_task method is called before nr_running is
943 * decreased. We remove the task from the rbtree and
944 * update the fair scheduling stats:
945 */
946 static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
947 {
948 struct cfs_rq *cfs_rq;
949 struct sched_entity *se = &p->se;
950
951 for_each_sched_entity(se) {
952 cfs_rq = cfs_rq_of(se);
953 dequeue_entity(cfs_rq, se, sleep);
954 /* Don't dequeue parent if it has other entities besides us */
955 if (cfs_rq->load.weight)
956 break;
957 sleep = 1;
958 }
959
960 hrtick_update(rq);
961 }
962
963 /*
964 * sched_yield() support is very simple - we dequeue and enqueue.
965 *
966 * If compat_yield is turned on then we requeue to the end of the tree.
967 */
968 static void yield_task_fair(struct rq *rq)
969 {
970 struct task_struct *curr = rq->curr;
971 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
972 struct sched_entity *rightmost, *se = &curr->se;
973
974 /*
975 * Are we the only task in the tree?
976 */
977 if (unlikely(cfs_rq->nr_running == 1))
978 return;
979
980 if (likely(!sysctl_sched_compat_yield) && curr->policy != SCHED_BATCH) {
981 update_rq_clock(rq);
982 /*
983 * Update run-time statistics of the 'current'.
984 */
985 update_curr(cfs_rq);
986
987 return;
988 }
989 /*
990 * Find the rightmost entry in the rbtree:
991 */
992 rightmost = __pick_last_entity(cfs_rq);
993 /*
994 * Already in the rightmost position?
995 */
996 if (unlikely(!rightmost || rightmost->vruntime < se->vruntime))
997 return;
998
999 /*
1000 * Minimally necessary key value to be last in the tree:
1001 * Upon rescheduling, sched_class::put_prev_task() will place
1002 * 'current' within the tree based on its new key value.
1003 */
1004 se->vruntime = rightmost->vruntime + 1;
1005 }
1006
1007 /*
1008 * wake_idle() will wake a task on an idle cpu if task->cpu is
1009 * not idle and an idle cpu is available. The span of cpus to
1010 * search starts with cpus closest then further out as needed,
1011 * so we always favor a closer, idle cpu.
1012 * Domains may include CPUs that are not usable for migration,
1013 * hence we need to mask them out (cpu_active_map)
1014 *
1015 * Returns the CPU we should wake onto.
1016 */
1017 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1018 static int wake_idle(int cpu, struct task_struct *p)
1019 {
1020 cpumask_t tmp;
1021 struct sched_domain *sd;
1022 int i;
1023
1024 /*
1025 * If it is idle, then it is the best cpu to run this task.
1026 *
1027 * This cpu is also the best, if it has more than one task already.
1028 * Siblings must be also busy(in most cases) as they didn't already
1029 * pickup the extra load from this cpu and hence we need not check
1030 * sibling runqueue info. This will avoid the checks and cache miss
1031 * penalities associated with that.
1032 */
1033 if (idle_cpu(cpu) || cpu_rq(cpu)->cfs.nr_running > 1)
1034 return cpu;
1035
1036 for_each_domain(cpu, sd) {
1037 if ((sd->flags & SD_WAKE_IDLE)
1038 || ((sd->flags & SD_WAKE_IDLE_FAR)
1039 && !task_hot(p, task_rq(p)->clock, sd))) {
1040 cpus_and(tmp, sd->span, p->cpus_allowed);
1041 cpus_and(tmp, tmp, cpu_active_map);
1042 for_each_cpu_mask_nr(i, tmp) {
1043 if (idle_cpu(i)) {
1044 if (i != task_cpu(p)) {
1045 schedstat_inc(p,
1046 se.nr_wakeups_idle);
1047 }
1048 return i;
1049 }
1050 }
1051 } else {
1052 break;
1053 }
1054 }
1055 return cpu;
1056 }
1057 #else /* !ARCH_HAS_SCHED_WAKE_IDLE*/
1058 static inline int wake_idle(int cpu, struct task_struct *p)
1059 {
1060 return cpu;
1061 }
1062 #endif
1063
1064 #ifdef CONFIG_SMP
1065
1066 #ifdef CONFIG_FAIR_GROUP_SCHED
1067 /*
1068 * effective_load() calculates the load change as seen from the root_task_group
1069 *
1070 * Adding load to a group doesn't make a group heavier, but can cause movement
1071 * of group shares between cpus. Assuming the shares were perfectly aligned one
1072 * can calculate the shift in shares.
1073 *
1074 * The problem is that perfectly aligning the shares is rather expensive, hence
1075 * we try to avoid doing that too often - see update_shares(), which ratelimits
1076 * this change.
1077 *
1078 * We compensate this by not only taking the current delta into account, but
1079 * also considering the delta between when the shares were last adjusted and
1080 * now.
1081 *
1082 * We still saw a performance dip, some tracing learned us that between
1083 * cgroup:/ and cgroup:/foo balancing the number of affine wakeups increased
1084 * significantly. Therefore try to bias the error in direction of failing
1085 * the affine wakeup.
1086 *
1087 */
1088 static long effective_load(struct task_group *tg, int cpu,
1089 long wl, long wg)
1090 {
1091 struct sched_entity *se = tg->se[cpu];
1092
1093 if (!tg->parent)
1094 return wl;
1095
1096 /*
1097 * By not taking the decrease of shares on the other cpu into
1098 * account our error leans towards reducing the affine wakeups.
1099 */
1100 if (!wl && sched_feat(ASYM_EFF_LOAD))
1101 return wl;
1102
1103 for_each_sched_entity(se) {
1104 long S, rw, s, a, b;
1105 long more_w;
1106
1107 /*
1108 * Instead of using this increment, also add the difference
1109 * between when the shares were last updated and now.
1110 */
1111 more_w = se->my_q->load.weight - se->my_q->rq_weight;
1112 wl += more_w;
1113 wg += more_w;
1114
1115 S = se->my_q->tg->shares;
1116 s = se->my_q->shares;
1117 rw = se->my_q->rq_weight;
1118
1119 a = S*(rw + wl);
1120 b = S*rw + s*wg;
1121
1122 wl = s*(a-b);
1123
1124 if (likely(b))
1125 wl /= b;
1126
1127 /*
1128 * Assume the group is already running and will
1129 * thus already be accounted for in the weight.
1130 *
1131 * That is, moving shares between CPUs, does not
1132 * alter the group weight.
1133 */
1134 wg = 0;
1135 }
1136
1137 return wl;
1138 }
1139
1140 #else
1141
1142 static inline unsigned long effective_load(struct task_group *tg, int cpu,
1143 unsigned long wl, unsigned long wg)
1144 {
1145 return wl;
1146 }
1147
1148 #endif
1149
1150 static int
1151 wake_affine(struct sched_domain *this_sd, struct rq *this_rq,
1152 struct task_struct *p, int prev_cpu, int this_cpu, int sync,
1153 int idx, unsigned long load, unsigned long this_load,
1154 unsigned int imbalance)
1155 {
1156 struct task_struct *curr = this_rq->curr;
1157 struct task_group *tg;
1158 unsigned long tl = this_load;
1159 unsigned long tl_per_task;
1160 unsigned long weight;
1161 int balanced;
1162
1163 if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS))
1164 return 0;
1165
1166 if (sync && (curr->se.avg_overlap > sysctl_sched_migration_cost ||
1167 p->se.avg_overlap > sysctl_sched_migration_cost))
1168 sync = 0;
1169
1170 /*
1171 * If sync wakeup then subtract the (maximum possible)
1172 * effect of the currently running task from the load
1173 * of the current CPU:
1174 */
1175 if (sync) {
1176 tg = task_group(current);
1177 weight = current->se.load.weight;
1178
1179 tl += effective_load(tg, this_cpu, -weight, -weight);
1180 load += effective_load(tg, prev_cpu, 0, -weight);
1181 }
1182
1183 tg = task_group(p);
1184 weight = p->se.load.weight;
1185
1186 balanced = 100*(tl + effective_load(tg, this_cpu, weight, weight)) <=
1187 imbalance*(load + effective_load(tg, prev_cpu, 0, weight));
1188
1189 /*
1190 * If the currently running task will sleep within
1191 * a reasonable amount of time then attract this newly
1192 * woken task:
1193 */
1194 if (sync && balanced)
1195 return 1;
1196
1197 schedstat_inc(p, se.nr_wakeups_affine_attempts);
1198 tl_per_task = cpu_avg_load_per_task(this_cpu);
1199
1200 if (balanced || (tl <= load && tl + target_load(prev_cpu, idx) <=
1201 tl_per_task)) {
1202 /*
1203 * This domain has SD_WAKE_AFFINE and
1204 * p is cache cold in this domain, and
1205 * there is no bad imbalance.
1206 */
1207 schedstat_inc(this_sd, ttwu_move_affine);
1208 schedstat_inc(p, se.nr_wakeups_affine);
1209
1210 return 1;
1211 }
1212 return 0;
1213 }
1214
1215 static int select_task_rq_fair(struct task_struct *p, int sync)
1216 {
1217 struct sched_domain *sd, *this_sd = NULL;
1218 int prev_cpu, this_cpu, new_cpu;
1219 unsigned long load, this_load;
1220 struct rq *this_rq;
1221 unsigned int imbalance;
1222 int idx;
1223
1224 prev_cpu = task_cpu(p);
1225 this_cpu = smp_processor_id();
1226 this_rq = cpu_rq(this_cpu);
1227 new_cpu = prev_cpu;
1228
1229 if (prev_cpu == this_cpu)
1230 goto out;
1231 /*
1232 * 'this_sd' is the first domain that both
1233 * this_cpu and prev_cpu are present in:
1234 */
1235 for_each_domain(this_cpu, sd) {
1236 if (cpu_isset(prev_cpu, sd->span)) {
1237 this_sd = sd;
1238 break;
1239 }
1240 }
1241
1242 if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
1243 goto out;
1244
1245 /*
1246 * Check for affine wakeup and passive balancing possibilities.
1247 */
1248 if (!this_sd)
1249 goto out;
1250
1251 idx = this_sd->wake_idx;
1252
1253 imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
1254
1255 load = source_load(prev_cpu, idx);
1256 this_load = target_load(this_cpu, idx);
1257
1258 if (wake_affine(this_sd, this_rq, p, prev_cpu, this_cpu, sync, idx,
1259 load, this_load, imbalance))
1260 return this_cpu;
1261
1262 /*
1263 * Start passive balancing when half the imbalance_pct
1264 * limit is reached.
1265 */
1266 if (this_sd->flags & SD_WAKE_BALANCE) {
1267 if (imbalance*this_load <= 100*load) {
1268 schedstat_inc(this_sd, ttwu_move_balance);
1269 schedstat_inc(p, se.nr_wakeups_passive);
1270 return this_cpu;
1271 }
1272 }
1273
1274 out:
1275 return wake_idle(new_cpu, p);
1276 }
1277 #endif /* CONFIG_SMP */
1278
1279 static unsigned long wakeup_gran(struct sched_entity *se)
1280 {
1281 unsigned long gran = sysctl_sched_wakeup_granularity;
1282
1283 /*
1284 * More easily preempt - nice tasks, while not making it harder for
1285 * + nice tasks.
1286 */
1287 if (!sched_feat(ASYM_GRAN) || se->load.weight > NICE_0_LOAD)
1288 gran = calc_delta_fair(sysctl_sched_wakeup_granularity, se);
1289
1290 return gran;
1291 }
1292
1293 /*
1294 * Should 'se' preempt 'curr'.
1295 *
1296 * |s1
1297 * |s2
1298 * |s3
1299 * g
1300 * |<--->|c
1301 *
1302 * w(c, s1) = -1
1303 * w(c, s2) = 0
1304 * w(c, s3) = 1
1305 *
1306 */
1307 static int
1308 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
1309 {
1310 s64 gran, vdiff = curr->vruntime - se->vruntime;
1311
1312 if (vdiff <= 0)
1313 return -1;
1314
1315 gran = wakeup_gran(curr);
1316 if (vdiff > gran)
1317 return 1;
1318
1319 return 0;
1320 }
1321
1322 static void set_last_buddy(struct sched_entity *se)
1323 {
1324 for_each_sched_entity(se)
1325 cfs_rq_of(se)->last = se;
1326 }
1327
1328 static void set_next_buddy(struct sched_entity *se)
1329 {
1330 for_each_sched_entity(se)
1331 cfs_rq_of(se)->next = se;
1332 }
1333
1334 /*
1335 * Preempt the current task with a newly woken task if needed:
1336 */
1337 static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
1338 {
1339 struct task_struct *curr = rq->curr;
1340 struct sched_entity *se = &curr->se, *pse = &p->se;
1341
1342 if (unlikely(rt_prio(p->prio))) {
1343 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
1344
1345 update_rq_clock(rq);
1346 update_curr(cfs_rq);
1347 resched_task(curr);
1348 return;
1349 }
1350
1351 if (unlikely(p->sched_class != &fair_sched_class))
1352 return;
1353
1354 if (unlikely(se == pse))
1355 return;
1356
1357 /*
1358 * Only set the backward buddy when the current task is still on the
1359 * rq. This can happen when a wakeup gets interleaved with schedule on
1360 * the ->pre_schedule() or idle_balance() point, either of which can
1361 * drop the rq lock.
1362 *
1363 * Also, during early boot the idle thread is in the fair class, for
1364 * obvious reasons its a bad idea to schedule back to the idle thread.
1365 */
1366 if (sched_feat(LAST_BUDDY) && likely(se->on_rq && curr != rq->idle))
1367 set_last_buddy(se);
1368 set_next_buddy(pse);
1369
1370 /*
1371 * We can come here with TIF_NEED_RESCHED already set from new task
1372 * wake up path.
1373 */
1374 if (test_tsk_need_resched(curr))
1375 return;
1376
1377 /*
1378 * Batch tasks do not preempt (their preemption is driven by
1379 * the tick):
1380 */
1381 if (unlikely(p->policy == SCHED_BATCH))
1382 return;
1383
1384 if (!sched_feat(WAKEUP_PREEMPT))
1385 return;
1386
1387 if (sched_feat(WAKEUP_OVERLAP) && (sync ||
1388 (se->avg_overlap < sysctl_sched_migration_cost &&
1389 pse->avg_overlap < sysctl_sched_migration_cost))) {
1390 resched_task(curr);
1391 return;
1392 }
1393
1394 find_matching_se(&se, &pse);
1395
1396 while (se) {
1397 BUG_ON(!pse);
1398
1399 if (wakeup_preempt_entity(se, pse) == 1) {
1400 resched_task(curr);
1401 break;
1402 }
1403
1404 se = parent_entity(se);
1405 pse = parent_entity(pse);
1406 }
1407 }
1408
1409 static struct task_struct *pick_next_task_fair(struct rq *rq)
1410 {
1411 struct task_struct *p;
1412 struct cfs_rq *cfs_rq = &rq->cfs;
1413 struct sched_entity *se;
1414
1415 if (unlikely(!cfs_rq->nr_running))
1416 return NULL;
1417
1418 do {
1419 se = pick_next_entity(cfs_rq);
1420 set_next_entity(cfs_rq, se);
1421 cfs_rq = group_cfs_rq(se);
1422 } while (cfs_rq);
1423
1424 p = task_of(se);
1425 hrtick_start_fair(rq, p);
1426
1427 return p;
1428 }
1429
1430 /*
1431 * Account for a descheduled task:
1432 */
1433 static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
1434 {
1435 struct sched_entity *se = &prev->se;
1436 struct cfs_rq *cfs_rq;
1437
1438 for_each_sched_entity(se) {
1439 cfs_rq = cfs_rq_of(se);
1440 put_prev_entity(cfs_rq, se);
1441 }
1442 }
1443
1444 #ifdef CONFIG_SMP
1445 /**************************************************
1446 * Fair scheduling class load-balancing methods:
1447 */
1448
1449 /*
1450 * Load-balancing iterator. Note: while the runqueue stays locked
1451 * during the whole iteration, the current task might be
1452 * dequeued so the iterator has to be dequeue-safe. Here we
1453 * achieve that by always pre-iterating before returning
1454 * the current task:
1455 */
1456 static struct task_struct *
1457 __load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
1458 {
1459 struct task_struct *p = NULL;
1460 struct sched_entity *se;
1461
1462 if (next == &cfs_rq->tasks)
1463 return NULL;
1464
1465 se = list_entry(next, struct sched_entity, group_node);
1466 p = task_of(se);
1467 cfs_rq->balance_iterator = next->next;
1468
1469 return p;
1470 }
1471
1472 static struct task_struct *load_balance_start_fair(void *arg)
1473 {
1474 struct cfs_rq *cfs_rq = arg;
1475
1476 return __load_balance_iterator(cfs_rq, cfs_rq->tasks.next);
1477 }
1478
1479 static struct task_struct *load_balance_next_fair(void *arg)
1480 {
1481 struct cfs_rq *cfs_rq = arg;
1482
1483 return __load_balance_iterator(cfs_rq, cfs_rq->balance_iterator);
1484 }
1485
1486 static unsigned long
1487 __load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
1488 unsigned long max_load_move, struct sched_domain *sd,
1489 enum cpu_idle_type idle, int *all_pinned, int *this_best_prio,
1490 struct cfs_rq *cfs_rq)
1491 {
1492 struct rq_iterator cfs_rq_iterator;
1493
1494 cfs_rq_iterator.start = load_balance_start_fair;
1495 cfs_rq_iterator.next = load_balance_next_fair;
1496 cfs_rq_iterator.arg = cfs_rq;
1497
1498 return balance_tasks(this_rq, this_cpu, busiest,
1499 max_load_move, sd, idle, all_pinned,
1500 this_best_prio, &cfs_rq_iterator);
1501 }
1502
1503 #ifdef CONFIG_FAIR_GROUP_SCHED
1504 static unsigned long
1505 load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
1506 unsigned long max_load_move,
1507 struct sched_domain *sd, enum cpu_idle_type idle,
1508 int *all_pinned, int *this_best_prio)
1509 {
1510 long rem_load_move = max_load_move;
1511 int busiest_cpu = cpu_of(busiest);
1512 struct task_group *tg;
1513
1514 rcu_read_lock();
1515 update_h_load(busiest_cpu);
1516
1517 list_for_each_entry_rcu(tg, &task_groups, list) {
1518 struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu];
1519 unsigned long busiest_h_load = busiest_cfs_rq->h_load;
1520 unsigned long busiest_weight = busiest_cfs_rq->load.weight;
1521 u64 rem_load, moved_load;
1522
1523 /*
1524 * empty group
1525 */
1526 if (!busiest_cfs_rq->task_weight)
1527 continue;
1528
1529 rem_load = (u64)rem_load_move * busiest_weight;
1530 rem_load = div_u64(rem_load, busiest_h_load + 1);
1531
1532 moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
1533 rem_load, sd, idle, all_pinned, this_best_prio,
1534 tg->cfs_rq[busiest_cpu]);
1535
1536 if (!moved_load)
1537 continue;
1538
1539 moved_load *= busiest_h_load;
1540 moved_load = div_u64(moved_load, busiest_weight + 1);
1541
1542 rem_load_move -= moved_load;
1543 if (rem_load_move < 0)
1544 break;
1545 }
1546 rcu_read_unlock();
1547
1548 return max_load_move - rem_load_move;
1549 }
1550 #else
1551 static unsigned long
1552 load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
1553 unsigned long max_load_move,
1554 struct sched_domain *sd, enum cpu_idle_type idle,
1555 int *all_pinned, int *this_best_prio)
1556 {
1557 return __load_balance_fair(this_rq, this_cpu, busiest,
1558 max_load_move, sd, idle, all_pinned,
1559 this_best_prio, &busiest->cfs);
1560 }
1561 #endif
1562
1563 static int
1564 move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
1565 struct sched_domain *sd, enum cpu_idle_type idle)
1566 {
1567 struct cfs_rq *busy_cfs_rq;
1568 struct rq_iterator cfs_rq_iterator;
1569
1570 cfs_rq_iterator.start = load_balance_start_fair;
1571 cfs_rq_iterator.next = load_balance_next_fair;
1572
1573 for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
1574 /*
1575 * pass busy_cfs_rq argument into
1576 * load_balance_[start|next]_fair iterators
1577 */
1578 cfs_rq_iterator.arg = busy_cfs_rq;
1579 if (iter_move_one_task(this_rq, this_cpu, busiest, sd, idle,
1580 &cfs_rq_iterator))
1581 return 1;
1582 }
1583
1584 return 0;
1585 }
1586 #endif /* CONFIG_SMP */
1587
1588 /*
1589 * scheduler tick hitting a task of our scheduling class:
1590 */
1591 static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
1592 {
1593 struct cfs_rq *cfs_rq;
1594 struct sched_entity *se = &curr->se;
1595
1596 for_each_sched_entity(se) {
1597 cfs_rq = cfs_rq_of(se);
1598 entity_tick(cfs_rq, se, queued);
1599 }
1600 }
1601
1602 #define swap(a, b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0)
1603
1604 /*
1605 * Share the fairness runtime between parent and child, thus the
1606 * total amount of pressure for CPU stays equal - new tasks
1607 * get a chance to run but frequent forkers are not allowed to
1608 * monopolize the CPU. Note: the parent runqueue is locked,
1609 * the child is not running yet.
1610 */
1611 static void task_new_fair(struct rq *rq, struct task_struct *p)
1612 {
1613 struct cfs_rq *cfs_rq = task_cfs_rq(p);
1614 struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
1615 int this_cpu = smp_processor_id();
1616
1617 sched_info_queued(p);
1618
1619 update_curr(cfs_rq);
1620 place_entity(cfs_rq, se, 1);
1621
1622 /* 'curr' will be NULL if the child belongs to a different group */
1623 if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) &&
1624 curr && curr->vruntime < se->vruntime) {
1625 /*
1626 * Upon rescheduling, sched_class::put_prev_task() will place
1627 * 'current' within the tree based on its new key value.
1628 */
1629 swap(curr->vruntime, se->vruntime);
1630 resched_task(rq->curr);
1631 }
1632
1633 enqueue_task_fair(rq, p, 0);
1634 }
1635
1636 /*
1637 * Priority of the task has changed. Check to see if we preempt
1638 * the current task.
1639 */
1640 static void prio_changed_fair(struct rq *rq, struct task_struct *p,
1641 int oldprio, int running)
1642 {
1643 /*
1644 * Reschedule if we are currently running on this runqueue and
1645 * our priority decreased, or if we are not currently running on
1646 * this runqueue and our priority is higher than the current's
1647 */
1648 if (running) {
1649 if (p->prio > oldprio)
1650 resched_task(rq->curr);
1651 } else
1652 check_preempt_curr(rq, p, 0);
1653 }
1654
1655 /*
1656 * We switched to the sched_fair class.
1657 */
1658 static void switched_to_fair(struct rq *rq, struct task_struct *p,
1659 int running)
1660 {
1661 /*
1662 * We were most likely switched from sched_rt, so
1663 * kick off the schedule if running, otherwise just see
1664 * if we can still preempt the current task.
1665 */
1666 if (running)
1667 resched_task(rq->curr);
1668 else
1669 check_preempt_curr(rq, p, 0);
1670 }
1671
1672 /* Account for a task changing its policy or group.
1673 *
1674 * This routine is mostly called to set cfs_rq->curr field when a task
1675 * migrates between groups/classes.
1676 */
1677 static void set_curr_task_fair(struct rq *rq)
1678 {
1679 struct sched_entity *se = &rq->curr->se;
1680
1681 for_each_sched_entity(se)
1682 set_next_entity(cfs_rq_of(se), se);
1683 }
1684
1685 #ifdef CONFIG_FAIR_GROUP_SCHED
1686 static void moved_group_fair(struct task_struct *p)
1687 {
1688 struct cfs_rq *cfs_rq = task_cfs_rq(p);
1689
1690 update_curr(cfs_rq);
1691 place_entity(cfs_rq, &p->se, 1);
1692 }
1693 #endif
1694
1695 /*
1696 * All the scheduling class methods:
1697 */
1698 static const struct sched_class fair_sched_class = {
1699 .next = &idle_sched_class,
1700 .enqueue_task = enqueue_task_fair,
1701 .dequeue_task = dequeue_task_fair,
1702 .yield_task = yield_task_fair,
1703
1704 .check_preempt_curr = check_preempt_wakeup,
1705
1706 .pick_next_task = pick_next_task_fair,
1707 .put_prev_task = put_prev_task_fair,
1708
1709 #ifdef CONFIG_SMP
1710 .select_task_rq = select_task_rq_fair,
1711
1712 .load_balance = load_balance_fair,
1713 .move_one_task = move_one_task_fair,
1714 #endif
1715
1716 .set_curr_task = set_curr_task_fair,
1717 .task_tick = task_tick_fair,
1718 .task_new = task_new_fair,
1719
1720 .prio_changed = prio_changed_fair,
1721 .switched_to = switched_to_fair,
1722
1723 #ifdef CONFIG_FAIR_GROUP_SCHED
1724 .moved_group = moved_group_fair,
1725 #endif
1726 };
1727
1728 #ifdef CONFIG_SCHED_DEBUG
1729 static void print_cfs_stats(struct seq_file *m, int cpu)
1730 {
1731 struct cfs_rq *cfs_rq;
1732
1733 rcu_read_lock();
1734 for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
1735 print_cfs_rq(m, cpu, cfs_rq);
1736 rcu_read_unlock();
1737 }
1738 #endif