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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#include <linux/sched.h>
25#include <linux/cpumask.h>
26
27/*
28 * Targeted preemption latency for CPU-bound tasks:
29 * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
30 *
31 * NOTE: this latency value is not the same as the concept of
32 * 'timeslice length' - timeslices in CFS are of variable length
33 * and have no persistent notion like in traditional, time-slice
34 * based scheduling concepts.
35 *
36 * (to see the precise effective timeslice length of your workload,
37 * run vmstat and monitor the context-switches (cs) field)
38 */
39unsigned int sysctl_sched_latency = 6000000ULL;
40unsigned int normalized_sysctl_sched_latency = 6000000ULL;
41
42/*
43 * The initial- and re-scaling of tunables is configurable
44 * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
45 *
46 * Options are:
47 * SCHED_TUNABLESCALING_NONE - unscaled, always *1
48 * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
49 * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
50 */
51enum sched_tunable_scaling sysctl_sched_tunable_scaling
52 = SCHED_TUNABLESCALING_LOG;
53
54/*
55 * Minimal preemption granularity for CPU-bound tasks:
56 * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
57 */
58unsigned int sysctl_sched_min_granularity = 750000ULL;
59unsigned int normalized_sysctl_sched_min_granularity = 750000ULL;
60
61/*
62 * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
63 */
64static unsigned int sched_nr_latency = 8;
65
66/*
67 * After fork, child runs first. If set to 0 (default) then
68 * parent will (try to) run first.
69 */
70unsigned int sysctl_sched_child_runs_first __read_mostly;
71
72/*
73 * SCHED_OTHER wake-up granularity.
74 * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
75 *
76 * This option delays the preemption effects of decoupled workloads
77 * and reduces their over-scheduling. Synchronous workloads will still
78 * have immediate wakeup/sleep latencies.
79 */
80unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
81unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
82
83const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
84
85/*
86 * The exponential sliding window over which load is averaged for shares
87 * distribution.
88 * (default: 10msec)
89 */
90unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
91
92static const struct sched_class fair_sched_class;
93
94/**************************************************************
95 * CFS operations on generic schedulable entities:
96 */
97
98#ifdef CONFIG_FAIR_GROUP_SCHED
99
100/* cpu runqueue to which this cfs_rq is attached */
101static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
102{
103 return cfs_rq->rq;
104}
105
106/* An entity is a task if it doesn't "own" a runqueue */
107#define entity_is_task(se) (!se->my_q)
108
109static inline struct task_struct *task_of(struct sched_entity *se)
110{
111#ifdef CONFIG_SCHED_DEBUG
112 WARN_ON_ONCE(!entity_is_task(se));
113#endif
114 return container_of(se, struct task_struct, se);
115}
116
117/* Walk up scheduling entities hierarchy */
118#define for_each_sched_entity(se) \
119 for (; se; se = se->parent)
120
121static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
122{
123 return p->se.cfs_rq;
124}
125
126/* runqueue on which this entity is (to be) queued */
127static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
128{
129 return se->cfs_rq;
130}
131
132/* runqueue "owned" by this group */
133static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
134{
135 return grp->my_q;
136}
137
138static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
139{
140 if (!cfs_rq->on_list) {
141 /*
142 * Ensure we either appear before our parent (if already
143 * enqueued) or force our parent to appear after us when it is
144 * enqueued. The fact that we always enqueue bottom-up
145 * reduces this to two cases.
146 */
147 if (cfs_rq->tg->parent &&
148 cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) {
149 list_add_rcu(&cfs_rq->leaf_cfs_rq_list,
150 &rq_of(cfs_rq)->leaf_cfs_rq_list);
151 } else {
152 list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
153 &rq_of(cfs_rq)->leaf_cfs_rq_list);
154 }
155
156 cfs_rq->on_list = 1;
157 }
158}
159
160static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
161{
162 if (cfs_rq->on_list) {
163 list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
164 cfs_rq->on_list = 0;
165 }
166}
167
168/* Iterate thr' all leaf cfs_rq's on a runqueue */
169#define for_each_leaf_cfs_rq(rq, cfs_rq) \
170 list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
171
172/* Do the two (enqueued) entities belong to the same group ? */
173static inline int
174is_same_group(struct sched_entity *se, struct sched_entity *pse)
175{
176 if (se->cfs_rq == pse->cfs_rq)
177 return 1;
178
179 return 0;
180}
181
182static inline struct sched_entity *parent_entity(struct sched_entity *se)
183{
184 return se->parent;
185}
186
187/* return depth at which a sched entity is present in the hierarchy */
188static inline int depth_se(struct sched_entity *se)
189{
190 int depth = 0;
191
192 for_each_sched_entity(se)
193 depth++;
194
195 return depth;
196}
197
198static void
199find_matching_se(struct sched_entity **se, struct sched_entity **pse)
200{
201 int se_depth, pse_depth;
202
203 /*
204 * preemption test can be made between sibling entities who are in the
205 * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
206 * both tasks until we find their ancestors who are siblings of common
207 * parent.
208 */
209
210 /* First walk up until both entities are at same depth */
211 se_depth = depth_se(*se);
212 pse_depth = depth_se(*pse);
213
214 while (se_depth > pse_depth) {
215 se_depth--;
216 *se = parent_entity(*se);
217 }
218
219 while (pse_depth > se_depth) {
220 pse_depth--;
221 *pse = parent_entity(*pse);
222 }
223
224 while (!is_same_group(*se, *pse)) {
225 *se = parent_entity(*se);
226 *pse = parent_entity(*pse);
227 }
228}
229
230#else /* !CONFIG_FAIR_GROUP_SCHED */
231
232static inline struct task_struct *task_of(struct sched_entity *se)
233{
234 return container_of(se, struct task_struct, se);
235}
236
237static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
238{
239 return container_of(cfs_rq, struct rq, cfs);
240}
241
242#define entity_is_task(se) 1
243
244#define for_each_sched_entity(se) \
245 for (; se; se = NULL)
246
247static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
248{
249 return &task_rq(p)->cfs;
250}
251
252static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
253{
254 struct task_struct *p = task_of(se);
255 struct rq *rq = task_rq(p);
256
257 return &rq->cfs;
258}
259
260/* runqueue "owned" by this group */
261static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
262{
263 return NULL;
264}
265
266static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
267{
268}
269
270static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
271{
272}
273
274#define for_each_leaf_cfs_rq(rq, cfs_rq) \
275 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
276
277static inline int
278is_same_group(struct sched_entity *se, struct sched_entity *pse)
279{
280 return 1;
281}
282
283static inline struct sched_entity *parent_entity(struct sched_entity *se)
284{
285 return NULL;
286}
287
288static inline void
289find_matching_se(struct sched_entity **se, struct sched_entity **pse)
290{
291}
292
293#endif /* CONFIG_FAIR_GROUP_SCHED */
294
295
296/**************************************************************
297 * Scheduling class tree data structure manipulation methods:
298 */
299
300static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime)
301{
302 s64 delta = (s64)(vruntime - min_vruntime);
303 if (delta > 0)
304 min_vruntime = vruntime;
305
306 return min_vruntime;
307}
308
309static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
310{
311 s64 delta = (s64)(vruntime - min_vruntime);
312 if (delta < 0)
313 min_vruntime = vruntime;
314
315 return min_vruntime;
316}
317
318static inline int entity_before(struct sched_entity *a,
319 struct sched_entity *b)
320{
321 return (s64)(a->vruntime - b->vruntime) < 0;
322}
323
324static void update_min_vruntime(struct cfs_rq *cfs_rq)
325{
326 u64 vruntime = cfs_rq->min_vruntime;
327
328 if (cfs_rq->curr)
329 vruntime = cfs_rq->curr->vruntime;
330
331 if (cfs_rq->rb_leftmost) {
332 struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost,
333 struct sched_entity,
334 run_node);
335
336 if (!cfs_rq->curr)
337 vruntime = se->vruntime;
338 else
339 vruntime = min_vruntime(vruntime, se->vruntime);
340 }
341
342 cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
343#ifndef CONFIG_64BIT
344 smp_wmb();
345 cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
346#endif
347}
348
349/*
350 * Enqueue an entity into the rb-tree:
351 */
352static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
353{
354 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
355 struct rb_node *parent = NULL;
356 struct sched_entity *entry;
357 int leftmost = 1;
358
359 /*
360 * Find the right place in the rbtree:
361 */
362 while (*link) {
363 parent = *link;
364 entry = rb_entry(parent, struct sched_entity, run_node);
365 /*
366 * We dont care about collisions. Nodes with
367 * the same key stay together.
368 */
369 if (entity_before(se, entry)) {
370 link = &parent->rb_left;
371 } else {
372 link = &parent->rb_right;
373 leftmost = 0;
374 }
375 }
376
377 /*
378 * Maintain a cache of leftmost tree entries (it is frequently
379 * used):
380 */
381 if (leftmost)
382 cfs_rq->rb_leftmost = &se->run_node;
383
384 rb_link_node(&se->run_node, parent, link);
385 rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
386}
387
388static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
389{
390 if (cfs_rq->rb_leftmost == &se->run_node) {
391 struct rb_node *next_node;
392
393 next_node = rb_next(&se->run_node);
394 cfs_rq->rb_leftmost = next_node;
395 }
396
397 rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
398}
399
400static struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
401{
402 struct rb_node *left = cfs_rq->rb_leftmost;
403
404 if (!left)
405 return NULL;
406
407 return rb_entry(left, struct sched_entity, run_node);
408}
409
410static struct sched_entity *__pick_next_entity(struct sched_entity *se)
411{
412 struct rb_node *next = rb_next(&se->run_node);
413
414 if (!next)
415 return NULL;
416
417 return rb_entry(next, struct sched_entity, run_node);
418}
419
420#ifdef CONFIG_SCHED_DEBUG
421static struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
422{
423 struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
424
425 if (!last)
426 return NULL;
427
428 return rb_entry(last, struct sched_entity, run_node);
429}
430
431/**************************************************************
432 * Scheduling class statistics methods:
433 */
434
435int sched_proc_update_handler(struct ctl_table *table, int write,
436 void __user *buffer, size_t *lenp,
437 loff_t *ppos)
438{
439 int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
440 int factor = get_update_sysctl_factor();
441
442 if (ret || !write)
443 return ret;
444
445 sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
446 sysctl_sched_min_granularity);
447
448#define WRT_SYSCTL(name) \
449 (normalized_sysctl_##name = sysctl_##name / (factor))
450 WRT_SYSCTL(sched_min_granularity);
451 WRT_SYSCTL(sched_latency);
452 WRT_SYSCTL(sched_wakeup_granularity);
453#undef WRT_SYSCTL
454
455 return 0;
456}
457#endif
458
459/*
460 * delta /= w
461 */
462static inline unsigned long
463calc_delta_fair(unsigned long delta, struct sched_entity *se)
464{
465 if (unlikely(se->load.weight != NICE_0_LOAD))
466 delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load);
467
468 return delta;
469}
470
471/*
472 * The idea is to set a period in which each task runs once.
473 *
474 * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
475 * this period because otherwise the slices get too small.
476 *
477 * p = (nr <= nl) ? l : l*nr/nl
478 */
479static u64 __sched_period(unsigned long nr_running)
480{
481 u64 period = sysctl_sched_latency;
482 unsigned long nr_latency = sched_nr_latency;
483
484 if (unlikely(nr_running > nr_latency)) {
485 period = sysctl_sched_min_granularity;
486 period *= nr_running;
487 }
488
489 return period;
490}
491
492/*
493 * We calculate the wall-time slice from the period by taking a part
494 * proportional to the weight.
495 *
496 * s = p*P[w/rw]
497 */
498static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
499{
500 u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq);
501
502 for_each_sched_entity(se) {
503 struct load_weight *load;
504 struct load_weight lw;
505
506 cfs_rq = cfs_rq_of(se);
507 load = &cfs_rq->load;
508
509 if (unlikely(!se->on_rq)) {
510 lw = cfs_rq->load;
511
512 update_load_add(&lw, se->load.weight);
513 load = &lw;
514 }
515 slice = calc_delta_mine(slice, se->load.weight, load);
516 }
517 return slice;
518}
519
520/*
521 * We calculate the vruntime slice of a to be inserted task
522 *
523 * vs = s/w
524 */
525static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
526{
527 return calc_delta_fair(sched_slice(cfs_rq, se), se);
528}
529
530static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update);
531static void update_cfs_shares(struct cfs_rq *cfs_rq);
532
533/*
534 * Update the current task's runtime statistics. Skip current tasks that
535 * are not in our scheduling class.
536 */
537static inline void
538__update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
539 unsigned long delta_exec)
540{
541 unsigned long delta_exec_weighted;
542
543 schedstat_set(curr->statistics.exec_max,
544 max((u64)delta_exec, curr->statistics.exec_max));
545
546 curr->sum_exec_runtime += delta_exec;
547 schedstat_add(cfs_rq, exec_clock, delta_exec);
548 delta_exec_weighted = calc_delta_fair(delta_exec, curr);
549
550 curr->vruntime += delta_exec_weighted;
551 update_min_vruntime(cfs_rq);
552
553#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
554 cfs_rq->load_unacc_exec_time += delta_exec;
555#endif
556}
557
558static void update_curr(struct cfs_rq *cfs_rq)
559{
560 struct sched_entity *curr = cfs_rq->curr;
561 u64 now = rq_of(cfs_rq)->clock_task;
562 unsigned long delta_exec;
563
564 if (unlikely(!curr))
565 return;
566
567 /*
568 * Get the amount of time the current task was running
569 * since the last time we changed load (this cannot
570 * overflow on 32 bits):
571 */
572 delta_exec = (unsigned long)(now - curr->exec_start);
573 if (!delta_exec)
574 return;
575
576 __update_curr(cfs_rq, curr, delta_exec);
577 curr->exec_start = now;
578
579 if (entity_is_task(curr)) {
580 struct task_struct *curtask = task_of(curr);
581
582 trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
583 cpuacct_charge(curtask, delta_exec);
584 account_group_exec_runtime(curtask, delta_exec);
585 }
586}
587
588static inline void
589update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
590{
591 schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock);
592}
593
594/*
595 * Task is being enqueued - update stats:
596 */
597static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
598{
599 /*
600 * Are we enqueueing a waiting task? (for current tasks
601 * a dequeue/enqueue event is a NOP)
602 */
603 if (se != cfs_rq->curr)
604 update_stats_wait_start(cfs_rq, se);
605}
606
607static void
608update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
609{
610 schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max,
611 rq_of(cfs_rq)->clock - se->statistics.wait_start));
612 schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1);
613 schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum +
614 rq_of(cfs_rq)->clock - se->statistics.wait_start);
615#ifdef CONFIG_SCHEDSTATS
616 if (entity_is_task(se)) {
617 trace_sched_stat_wait(task_of(se),
618 rq_of(cfs_rq)->clock - se->statistics.wait_start);
619 }
620#endif
621 schedstat_set(se->statistics.wait_start, 0);
622}
623
624static inline void
625update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
626{
627 /*
628 * Mark the end of the wait period if dequeueing a
629 * waiting task:
630 */
631 if (se != cfs_rq->curr)
632 update_stats_wait_end(cfs_rq, se);
633}
634
635/*
636 * We are picking a new current task - update its stats:
637 */
638static inline void
639update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
640{
641 /*
642 * We are starting a new run period:
643 */
644 se->exec_start = rq_of(cfs_rq)->clock_task;
645}
646
647/**************************************************
648 * Scheduling class queueing methods:
649 */
650
651#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
652static void
653add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
654{
655 cfs_rq->task_weight += weight;
656}
657#else
658static inline void
659add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
660{
661}
662#endif
663
664static void
665account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
666{
667 update_load_add(&cfs_rq->load, se->load.weight);
668 if (!parent_entity(se))
669 inc_cpu_load(rq_of(cfs_rq), se->load.weight);
670 if (entity_is_task(se)) {
671 add_cfs_task_weight(cfs_rq, se->load.weight);
672 list_add(&se->group_node, &cfs_rq->tasks);
673 }
674 cfs_rq->nr_running++;
675}
676
677static void
678account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
679{
680 update_load_sub(&cfs_rq->load, se->load.weight);
681 if (!parent_entity(se))
682 dec_cpu_load(rq_of(cfs_rq), se->load.weight);
683 if (entity_is_task(se)) {
684 add_cfs_task_weight(cfs_rq, -se->load.weight);
685 list_del_init(&se->group_node);
686 }
687 cfs_rq->nr_running--;
688}
689
690#ifdef CONFIG_FAIR_GROUP_SCHED
691# ifdef CONFIG_SMP
692static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq,
693 int global_update)
694{
695 struct task_group *tg = cfs_rq->tg;
696 long load_avg;
697
698 load_avg = div64_u64(cfs_rq->load_avg, cfs_rq->load_period+1);
699 load_avg -= cfs_rq->load_contribution;
700
701 if (global_update || abs(load_avg) > cfs_rq->load_contribution / 8) {
702 atomic_add(load_avg, &tg->load_weight);
703 cfs_rq->load_contribution += load_avg;
704 }
705}
706
707static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
708{
709 u64 period = sysctl_sched_shares_window;
710 u64 now, delta;
711 unsigned long load = cfs_rq->load.weight;
712
713 if (cfs_rq->tg == &root_task_group)
714 return;
715
716 now = rq_of(cfs_rq)->clock_task;
717 delta = now - cfs_rq->load_stamp;
718
719 /* truncate load history at 4 idle periods */
720 if (cfs_rq->load_stamp > cfs_rq->load_last &&
721 now - cfs_rq->load_last > 4 * period) {
722 cfs_rq->load_period = 0;
723 cfs_rq->load_avg = 0;
724 delta = period - 1;
725 }
726
727 cfs_rq->load_stamp = now;
728 cfs_rq->load_unacc_exec_time = 0;
729 cfs_rq->load_period += delta;
730 if (load) {
731 cfs_rq->load_last = now;
732 cfs_rq->load_avg += delta * load;
733 }
734
735 /* consider updating load contribution on each fold or truncate */
736 if (global_update || cfs_rq->load_period > period
737 || !cfs_rq->load_period)
738 update_cfs_rq_load_contribution(cfs_rq, global_update);
739
740 while (cfs_rq->load_period > period) {
741 /*
742 * Inline assembly required to prevent the compiler
743 * optimising this loop into a divmod call.
744 * See __iter_div_u64_rem() for another example of this.
745 */
746 asm("" : "+rm" (cfs_rq->load_period));
747 cfs_rq->load_period /= 2;
748 cfs_rq->load_avg /= 2;
749 }
750
751 if (!cfs_rq->curr && !cfs_rq->nr_running && !cfs_rq->load_avg)
752 list_del_leaf_cfs_rq(cfs_rq);
753}
754
755static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
756{
757 long load_weight, load, shares;
758
759 load = cfs_rq->load.weight;
760
761 load_weight = atomic_read(&tg->load_weight);
762 load_weight += load;
763 load_weight -= cfs_rq->load_contribution;
764
765 shares = (tg->shares * load);
766 if (load_weight)
767 shares /= load_weight;
768
769 if (shares < MIN_SHARES)
770 shares = MIN_SHARES;
771 if (shares > tg->shares)
772 shares = tg->shares;
773
774 return shares;
775}
776
777static void update_entity_shares_tick(struct cfs_rq *cfs_rq)
778{
779 if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
780 update_cfs_load(cfs_rq, 0);
781 update_cfs_shares(cfs_rq);
782 }
783}
784# else /* CONFIG_SMP */
785static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
786{
787}
788
789static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
790{
791 return tg->shares;
792}
793
794static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
795{
796}
797# endif /* CONFIG_SMP */
798static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
799 unsigned long weight)
800{
801 if (se->on_rq) {
802 /* commit outstanding execution time */
803 if (cfs_rq->curr == se)
804 update_curr(cfs_rq);
805 account_entity_dequeue(cfs_rq, se);
806 }
807
808 update_load_set(&se->load, weight);
809
810 if (se->on_rq)
811 account_entity_enqueue(cfs_rq, se);
812}
813
814static void update_cfs_shares(struct cfs_rq *cfs_rq)
815{
816 struct task_group *tg;
817 struct sched_entity *se;
818 long shares;
819
820 tg = cfs_rq->tg;
821 se = tg->se[cpu_of(rq_of(cfs_rq))];
822 if (!se)
823 return;
824#ifndef CONFIG_SMP
825 if (likely(se->load.weight == tg->shares))
826 return;
827#endif
828 shares = calc_cfs_shares(cfs_rq, tg);
829
830 reweight_entity(cfs_rq_of(se), se, shares);
831}
832#else /* CONFIG_FAIR_GROUP_SCHED */
833static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
834{
835}
836
837static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
838{
839}
840
841static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
842{
843}
844#endif /* CONFIG_FAIR_GROUP_SCHED */
845
846static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
847{
848#ifdef CONFIG_SCHEDSTATS
849 struct task_struct *tsk = NULL;
850
851 if (entity_is_task(se))
852 tsk = task_of(se);
853
854 if (se->statistics.sleep_start) {
855 u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start;
856
857 if ((s64)delta < 0)
858 delta = 0;
859
860 if (unlikely(delta > se->statistics.sleep_max))
861 se->statistics.sleep_max = delta;
862
863 se->statistics.sleep_start = 0;
864 se->statistics.sum_sleep_runtime += delta;
865
866 if (tsk) {
867 account_scheduler_latency(tsk, delta >> 10, 1);
868 trace_sched_stat_sleep(tsk, delta);
869 }
870 }
871 if (se->statistics.block_start) {
872 u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start;
873
874 if ((s64)delta < 0)
875 delta = 0;
876
877 if (unlikely(delta > se->statistics.block_max))
878 se->statistics.block_max = delta;
879
880 se->statistics.block_start = 0;
881 se->statistics.sum_sleep_runtime += delta;
882
883 if (tsk) {
884 if (tsk->in_iowait) {
885 se->statistics.iowait_sum += delta;
886 se->statistics.iowait_count++;
887 trace_sched_stat_iowait(tsk, delta);
888 }
889
890 /*
891 * Blocking time is in units of nanosecs, so shift by
892 * 20 to get a milliseconds-range estimation of the
893 * amount of time that the task spent sleeping:
894 */
895 if (unlikely(prof_on == SLEEP_PROFILING)) {
896 profile_hits(SLEEP_PROFILING,
897 (void *)get_wchan(tsk),
898 delta >> 20);
899 }
900 account_scheduler_latency(tsk, delta >> 10, 0);
901 }
902 }
903#endif
904}
905
906static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
907{
908#ifdef CONFIG_SCHED_DEBUG
909 s64 d = se->vruntime - cfs_rq->min_vruntime;
910
911 if (d < 0)
912 d = -d;
913
914 if (d > 3*sysctl_sched_latency)
915 schedstat_inc(cfs_rq, nr_spread_over);
916#endif
917}
918
919static void
920place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
921{
922 u64 vruntime = cfs_rq->min_vruntime;
923
924 /*
925 * The 'current' period is already promised to the current tasks,
926 * however the extra weight of the new task will slow them down a
927 * little, place the new task so that it fits in the slot that
928 * stays open at the end.
929 */
930 if (initial && sched_feat(START_DEBIT))
931 vruntime += sched_vslice(cfs_rq, se);
932
933 /* sleeps up to a single latency don't count. */
934 if (!initial) {
935 unsigned long thresh = sysctl_sched_latency;
936
937 /*
938 * Halve their sleep time's effect, to allow
939 * for a gentler effect of sleepers:
940 */
941 if (sched_feat(GENTLE_FAIR_SLEEPERS))
942 thresh >>= 1;
943
944 vruntime -= thresh;
945 }
946
947 /* ensure we never gain time by being placed backwards. */
948 vruntime = max_vruntime(se->vruntime, vruntime);
949
950 se->vruntime = vruntime;
951}
952
953static void
954enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
955{
956 /*
957 * Update the normalized vruntime before updating min_vruntime
958 * through callig update_curr().
959 */
960 if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING))
961 se->vruntime += cfs_rq->min_vruntime;
962
963 /*
964 * Update run-time statistics of the 'current'.
965 */
966 update_curr(cfs_rq);
967 update_cfs_load(cfs_rq, 0);
968 account_entity_enqueue(cfs_rq, se);
969 update_cfs_shares(cfs_rq);
970
971 if (flags & ENQUEUE_WAKEUP) {
972 place_entity(cfs_rq, se, 0);
973 enqueue_sleeper(cfs_rq, se);
974 }
975
976 update_stats_enqueue(cfs_rq, se);
977 check_spread(cfs_rq, se);
978 if (se != cfs_rq->curr)
979 __enqueue_entity(cfs_rq, se);
980 se->on_rq = 1;
981
982 if (cfs_rq->nr_running == 1)
983 list_add_leaf_cfs_rq(cfs_rq);
984}
985
986static void __clear_buddies_last(struct sched_entity *se)
987{
988 for_each_sched_entity(se) {
989 struct cfs_rq *cfs_rq = cfs_rq_of(se);
990 if (cfs_rq->last == se)
991 cfs_rq->last = NULL;
992 else
993 break;
994 }
995}
996
997static void __clear_buddies_next(struct sched_entity *se)
998{
999 for_each_sched_entity(se) {
1000 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1001 if (cfs_rq->next == se)
1002 cfs_rq->next = NULL;
1003 else
1004 break;
1005 }
1006}
1007
1008static void __clear_buddies_skip(struct sched_entity *se)
1009{
1010 for_each_sched_entity(se) {
1011 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1012 if (cfs_rq->skip == se)
1013 cfs_rq->skip = NULL;
1014 else
1015 break;
1016 }
1017}
1018
1019static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
1020{
1021 if (cfs_rq->last == se)
1022 __clear_buddies_last(se);
1023
1024 if (cfs_rq->next == se)
1025 __clear_buddies_next(se);
1026
1027 if (cfs_rq->skip == se)
1028 __clear_buddies_skip(se);
1029}
1030
1031static void
1032dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1033{
1034 /*
1035 * Update run-time statistics of the 'current'.
1036 */
1037 update_curr(cfs_rq);
1038
1039 update_stats_dequeue(cfs_rq, se);
1040 if (flags & DEQUEUE_SLEEP) {
1041#ifdef CONFIG_SCHEDSTATS
1042 if (entity_is_task(se)) {
1043 struct task_struct *tsk = task_of(se);
1044
1045 if (tsk->state & TASK_INTERRUPTIBLE)
1046 se->statistics.sleep_start = rq_of(cfs_rq)->clock;
1047 if (tsk->state & TASK_UNINTERRUPTIBLE)
1048 se->statistics.block_start = rq_of(cfs_rq)->clock;
1049 }
1050#endif
1051 }
1052
1053 clear_buddies(cfs_rq, se);
1054
1055 if (se != cfs_rq->curr)
1056 __dequeue_entity(cfs_rq, se);
1057 se->on_rq = 0;
1058 update_cfs_load(cfs_rq, 0);
1059 account_entity_dequeue(cfs_rq, se);
1060
1061 /*
1062 * Normalize the entity after updating the min_vruntime because the
1063 * update can refer to the ->curr item and we need to reflect this
1064 * movement in our normalized position.
1065 */
1066 if (!(flags & DEQUEUE_SLEEP))
1067 se->vruntime -= cfs_rq->min_vruntime;
1068
1069 update_min_vruntime(cfs_rq);
1070 update_cfs_shares(cfs_rq);
1071}
1072
1073/*
1074 * Preempt the current task with a newly woken task if needed:
1075 */
1076static void
1077check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
1078{
1079 unsigned long ideal_runtime, delta_exec;
1080
1081 ideal_runtime = sched_slice(cfs_rq, curr);
1082 delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
1083 if (delta_exec > ideal_runtime) {
1084 resched_task(rq_of(cfs_rq)->curr);
1085 /*
1086 * The current task ran long enough, ensure it doesn't get
1087 * re-elected due to buddy favours.
1088 */
1089 clear_buddies(cfs_rq, curr);
1090 return;
1091 }
1092
1093 /*
1094 * Ensure that a task that missed wakeup preemption by a
1095 * narrow margin doesn't have to wait for a full slice.
1096 * This also mitigates buddy induced latencies under load.
1097 */
1098 if (!sched_feat(WAKEUP_PREEMPT))
1099 return;
1100
1101 if (delta_exec < sysctl_sched_min_granularity)
1102 return;
1103
1104 if (cfs_rq->nr_running > 1) {
1105 struct sched_entity *se = __pick_first_entity(cfs_rq);
1106 s64 delta = curr->vruntime - se->vruntime;
1107
1108 if (delta < 0)
1109 return;
1110
1111 if (delta > ideal_runtime)
1112 resched_task(rq_of(cfs_rq)->curr);
1113 }
1114}
1115
1116static void
1117set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
1118{
1119 /* 'current' is not kept within the tree. */
1120 if (se->on_rq) {
1121 /*
1122 * Any task has to be enqueued before it get to execute on
1123 * a CPU. So account for the time it spent waiting on the
1124 * runqueue.
1125 */
1126 update_stats_wait_end(cfs_rq, se);
1127 __dequeue_entity(cfs_rq, se);
1128 }
1129
1130 update_stats_curr_start(cfs_rq, se);
1131 cfs_rq->curr = se;
1132#ifdef CONFIG_SCHEDSTATS
1133 /*
1134 * Track our maximum slice length, if the CPU's load is at
1135 * least twice that of our own weight (i.e. dont track it
1136 * when there are only lesser-weight tasks around):
1137 */
1138 if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
1139 se->statistics.slice_max = max(se->statistics.slice_max,
1140 se->sum_exec_runtime - se->prev_sum_exec_runtime);
1141 }
1142#endif
1143 se->prev_sum_exec_runtime = se->sum_exec_runtime;
1144}
1145
1146static int
1147wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
1148
1149/*
1150 * Pick the next process, keeping these things in mind, in this order:
1151 * 1) keep things fair between processes/task groups
1152 * 2) pick the "next" process, since someone really wants that to run
1153 * 3) pick the "last" process, for cache locality
1154 * 4) do not run the "skip" process, if something else is available
1155 */
1156static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
1157{
1158 struct sched_entity *se = __pick_first_entity(cfs_rq);
1159 struct sched_entity *left = se;
1160
1161 /*
1162 * Avoid running the skip buddy, if running something else can
1163 * be done without getting too unfair.
1164 */
1165 if (cfs_rq->skip == se) {
1166 struct sched_entity *second = __pick_next_entity(se);
1167 if (second && wakeup_preempt_entity(second, left) < 1)
1168 se = second;
1169 }
1170
1171 /*
1172 * Prefer last buddy, try to return the CPU to a preempted task.
1173 */
1174 if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
1175 se = cfs_rq->last;
1176
1177 /*
1178 * Someone really wants this to run. If it's not unfair, run it.
1179 */
1180 if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
1181 se = cfs_rq->next;
1182
1183 clear_buddies(cfs_rq, se);
1184
1185 return se;
1186}
1187
1188static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
1189{
1190 /*
1191 * If still on the runqueue then deactivate_task()
1192 * was not called and update_curr() has to be done:
1193 */
1194 if (prev->on_rq)
1195 update_curr(cfs_rq);
1196
1197 check_spread(cfs_rq, prev);
1198 if (prev->on_rq) {
1199 update_stats_wait_start(cfs_rq, prev);
1200 /* Put 'current' back into the tree. */
1201 __enqueue_entity(cfs_rq, prev);
1202 }
1203 cfs_rq->curr = NULL;
1204}
1205
1206static void
1207entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
1208{
1209 /*
1210 * Update run-time statistics of the 'current'.
1211 */
1212 update_curr(cfs_rq);
1213
1214 /*
1215 * Update share accounting for long-running entities.
1216 */
1217 update_entity_shares_tick(cfs_rq);
1218
1219#ifdef CONFIG_SCHED_HRTICK
1220 /*
1221 * queued ticks are scheduled to match the slice, so don't bother
1222 * validating it and just reschedule.
1223 */
1224 if (queued) {
1225 resched_task(rq_of(cfs_rq)->curr);
1226 return;
1227 }
1228 /*
1229 * don't let the period tick interfere with the hrtick preemption
1230 */
1231 if (!sched_feat(DOUBLE_TICK) &&
1232 hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
1233 return;
1234#endif
1235
1236 if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
1237 check_preempt_tick(cfs_rq, curr);
1238}
1239
1240/**************************************************
1241 * CFS operations on tasks:
1242 */
1243
1244#ifdef CONFIG_SCHED_HRTICK
1245static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
1246{
1247 struct sched_entity *se = &p->se;
1248 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1249
1250 WARN_ON(task_rq(p) != rq);
1251
1252 if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) {
1253 u64 slice = sched_slice(cfs_rq, se);
1254 u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
1255 s64 delta = slice - ran;
1256
1257 if (delta < 0) {
1258 if (rq->curr == p)
1259 resched_task(p);
1260 return;
1261 }
1262
1263 /*
1264 * Don't schedule slices shorter than 10000ns, that just
1265 * doesn't make sense. Rely on vruntime for fairness.
1266 */
1267 if (rq->curr != p)
1268 delta = max_t(s64, 10000LL, delta);
1269
1270 hrtick_start(rq, delta);
1271 }
1272}
1273
1274/*
1275 * called from enqueue/dequeue and updates the hrtick when the
1276 * current task is from our class and nr_running is low enough
1277 * to matter.
1278 */
1279static void hrtick_update(struct rq *rq)
1280{
1281 struct task_struct *curr = rq->curr;
1282
1283 if (curr->sched_class != &fair_sched_class)
1284 return;
1285
1286 if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
1287 hrtick_start_fair(rq, curr);
1288}
1289#else /* !CONFIG_SCHED_HRTICK */
1290static inline void
1291hrtick_start_fair(struct rq *rq, struct task_struct *p)
1292{
1293}
1294
1295static inline void hrtick_update(struct rq *rq)
1296{
1297}
1298#endif
1299
1300/*
1301 * The enqueue_task method is called before nr_running is
1302 * increased. Here we update the fair scheduling stats and
1303 * then put the task into the rbtree:
1304 */
1305static void
1306enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
1307{
1308 struct cfs_rq *cfs_rq;
1309 struct sched_entity *se = &p->se;
1310
1311 for_each_sched_entity(se) {
1312 if (se->on_rq)
1313 break;
1314 cfs_rq = cfs_rq_of(se);
1315 enqueue_entity(cfs_rq, se, flags);
1316 flags = ENQUEUE_WAKEUP;
1317 }
1318
1319 for_each_sched_entity(se) {
1320 cfs_rq = cfs_rq_of(se);
1321
1322 update_cfs_load(cfs_rq, 0);
1323 update_cfs_shares(cfs_rq);
1324 }
1325
1326 hrtick_update(rq);
1327}
1328
1329static void set_next_buddy(struct sched_entity *se);
1330
1331/*
1332 * The dequeue_task method is called before nr_running is
1333 * decreased. We remove the task from the rbtree and
1334 * update the fair scheduling stats:
1335 */
1336static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
1337{
1338 struct cfs_rq *cfs_rq;
1339 struct sched_entity *se = &p->se;
1340 int task_sleep = flags & DEQUEUE_SLEEP;
1341
1342 for_each_sched_entity(se) {
1343 cfs_rq = cfs_rq_of(se);
1344 dequeue_entity(cfs_rq, se, flags);
1345
1346 /* Don't dequeue parent if it has other entities besides us */
1347 if (cfs_rq->load.weight) {
1348 /*
1349 * Bias pick_next to pick a task from this cfs_rq, as
1350 * p is sleeping when it is within its sched_slice.
1351 */
1352 if (task_sleep && parent_entity(se))
1353 set_next_buddy(parent_entity(se));
1354
1355 /* avoid re-evaluating load for this entity */
1356 se = parent_entity(se);
1357 break;
1358 }
1359 flags |= DEQUEUE_SLEEP;
1360 }
1361
1362 for_each_sched_entity(se) {
1363 cfs_rq = cfs_rq_of(se);
1364
1365 update_cfs_load(cfs_rq, 0);
1366 update_cfs_shares(cfs_rq);
1367 }
1368
1369 hrtick_update(rq);
1370}
1371
1372#ifdef CONFIG_SMP
1373
1374static void task_waking_fair(struct task_struct *p)
1375{
1376 struct sched_entity *se = &p->se;
1377 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1378 u64 min_vruntime;
1379
1380#ifndef CONFIG_64BIT
1381 u64 min_vruntime_copy;
1382
1383 do {
1384 min_vruntime_copy = cfs_rq->min_vruntime_copy;
1385 smp_rmb();
1386 min_vruntime = cfs_rq->min_vruntime;
1387 } while (min_vruntime != min_vruntime_copy);
1388#else
1389 min_vruntime = cfs_rq->min_vruntime;
1390#endif
1391
1392 se->vruntime -= min_vruntime;
1393}
1394
1395#ifdef CONFIG_FAIR_GROUP_SCHED
1396/*
1397 * effective_load() calculates the load change as seen from the root_task_group
1398 *
1399 * Adding load to a group doesn't make a group heavier, but can cause movement
1400 * of group shares between cpus. Assuming the shares were perfectly aligned one
1401 * can calculate the shift in shares.
1402 */
1403static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
1404{
1405 struct sched_entity *se = tg->se[cpu];
1406
1407 if (!tg->parent)
1408 return wl;
1409
1410 for_each_sched_entity(se) {
1411 long lw, w;
1412
1413 tg = se->my_q->tg;
1414 w = se->my_q->load.weight;
1415
1416 /* use this cpu's instantaneous contribution */
1417 lw = atomic_read(&tg->load_weight);
1418 lw -= se->my_q->load_contribution;
1419 lw += w + wg;
1420
1421 wl += w;
1422
1423 if (lw > 0 && wl < lw)
1424 wl = (wl * tg->shares) / lw;
1425 else
1426 wl = tg->shares;
1427
1428 /* zero point is MIN_SHARES */
1429 if (wl < MIN_SHARES)
1430 wl = MIN_SHARES;
1431 wl -= se->load.weight;
1432 wg = 0;
1433 }
1434
1435 return wl;
1436}
1437
1438#else
1439
1440static inline unsigned long effective_load(struct task_group *tg, int cpu,
1441 unsigned long wl, unsigned long wg)
1442{
1443 return wl;
1444}
1445
1446#endif
1447
1448static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
1449{
1450 s64 this_load, load;
1451 int idx, this_cpu, prev_cpu;
1452 unsigned long tl_per_task;
1453 struct task_group *tg;
1454 unsigned long weight;
1455 int balanced;
1456
1457 idx = sd->wake_idx;
1458 this_cpu = smp_processor_id();
1459 prev_cpu = task_cpu(p);
1460 load = source_load(prev_cpu, idx);
1461 this_load = target_load(this_cpu, idx);
1462
1463 /*
1464 * If sync wakeup then subtract the (maximum possible)
1465 * effect of the currently running task from the load
1466 * of the current CPU:
1467 */
1468 if (sync) {
1469 tg = task_group(current);
1470 weight = current->se.load.weight;
1471
1472 this_load += effective_load(tg, this_cpu, -weight, -weight);
1473 load += effective_load(tg, prev_cpu, 0, -weight);
1474 }
1475
1476 tg = task_group(p);
1477 weight = p->se.load.weight;
1478
1479 /*
1480 * In low-load situations, where prev_cpu is idle and this_cpu is idle
1481 * due to the sync cause above having dropped this_load to 0, we'll
1482 * always have an imbalance, but there's really nothing you can do
1483 * about that, so that's good too.
1484 *
1485 * Otherwise check if either cpus are near enough in load to allow this
1486 * task to be woken on this_cpu.
1487 */
1488 if (this_load > 0) {
1489 s64 this_eff_load, prev_eff_load;
1490
1491 this_eff_load = 100;
1492 this_eff_load *= power_of(prev_cpu);
1493 this_eff_load *= this_load +
1494 effective_load(tg, this_cpu, weight, weight);
1495
1496 prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2;
1497 prev_eff_load *= power_of(this_cpu);
1498 prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight);
1499
1500 balanced = this_eff_load <= prev_eff_load;
1501 } else
1502 balanced = true;
1503
1504 /*
1505 * If the currently running task will sleep within
1506 * a reasonable amount of time then attract this newly
1507 * woken task:
1508 */
1509 if (sync && balanced)
1510 return 1;
1511
1512 schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
1513 tl_per_task = cpu_avg_load_per_task(this_cpu);
1514
1515 if (balanced ||
1516 (this_load <= load &&
1517 this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
1518 /*
1519 * This domain has SD_WAKE_AFFINE and
1520 * p is cache cold in this domain, and
1521 * there is no bad imbalance.
1522 */
1523 schedstat_inc(sd, ttwu_move_affine);
1524 schedstat_inc(p, se.statistics.nr_wakeups_affine);
1525
1526 return 1;
1527 }
1528 return 0;
1529}
1530
1531/*
1532 * find_idlest_group finds and returns the least busy CPU group within the
1533 * domain.
1534 */
1535static struct sched_group *
1536find_idlest_group(struct sched_domain *sd, struct task_struct *p,
1537 int this_cpu, int load_idx)
1538{
1539 struct sched_group *idlest = NULL, *group = sd->groups;
1540 unsigned long min_load = ULONG_MAX, this_load = 0;
1541 int imbalance = 100 + (sd->imbalance_pct-100)/2;
1542
1543 do {
1544 unsigned long load, avg_load;
1545 int local_group;
1546 int i;
1547
1548 /* Skip over this group if it has no CPUs allowed */
1549 if (!cpumask_intersects(sched_group_cpus(group),
1550 &p->cpus_allowed))
1551 continue;
1552
1553 local_group = cpumask_test_cpu(this_cpu,
1554 sched_group_cpus(group));
1555
1556 /* Tally up the load of all CPUs in the group */
1557 avg_load = 0;
1558
1559 for_each_cpu(i, sched_group_cpus(group)) {
1560 /* Bias balancing toward cpus of our domain */
1561 if (local_group)
1562 load = source_load(i, load_idx);
1563 else
1564 load = target_load(i, load_idx);
1565
1566 avg_load += load;
1567 }
1568
1569 /* Adjust by relative CPU power of the group */
1570 avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power;
1571
1572 if (local_group) {
1573 this_load = avg_load;
1574 } else if (avg_load < min_load) {
1575 min_load = avg_load;
1576 idlest = group;
1577 }
1578 } while (group = group->next, group != sd->groups);
1579
1580 if (!idlest || 100*this_load < imbalance*min_load)
1581 return NULL;
1582 return idlest;
1583}
1584
1585/*
1586 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1587 */
1588static int
1589find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
1590{
1591 unsigned long load, min_load = ULONG_MAX;
1592 int idlest = -1;
1593 int i;
1594
1595 /* Traverse only the allowed CPUs */
1596 for_each_cpu_and(i, sched_group_cpus(group), &p->cpus_allowed) {
1597 load = weighted_cpuload(i);
1598
1599 if (load < min_load || (load == min_load && i == this_cpu)) {
1600 min_load = load;
1601 idlest = i;
1602 }
1603 }
1604
1605 return idlest;
1606}
1607
1608/*
1609 * Try and locate an idle CPU in the sched_domain.
1610 */
1611static int select_idle_sibling(struct task_struct *p, int target)
1612{
1613 int cpu = smp_processor_id();
1614 int prev_cpu = task_cpu(p);
1615 struct sched_domain *sd;
1616 int i;
1617
1618 /*
1619 * If the task is going to be woken-up on this cpu and if it is
1620 * already idle, then it is the right target.
1621 */
1622 if (target == cpu && idle_cpu(cpu))
1623 return cpu;
1624
1625 /*
1626 * If the task is going to be woken-up on the cpu where it previously
1627 * ran and if it is currently idle, then it the right target.
1628 */
1629 if (target == prev_cpu && idle_cpu(prev_cpu))
1630 return prev_cpu;
1631
1632 /*
1633 * Otherwise, iterate the domains and find an elegible idle cpu.
1634 */
1635 rcu_read_lock();
1636 for_each_domain(target, sd) {
1637 if (!(sd->flags & SD_SHARE_PKG_RESOURCES))
1638 break;
1639
1640 for_each_cpu_and(i, sched_domain_span(sd), &p->cpus_allowed) {
1641 if (idle_cpu(i)) {
1642 target = i;
1643 break;
1644 }
1645 }
1646
1647 /*
1648 * Lets stop looking for an idle sibling when we reached
1649 * the domain that spans the current cpu and prev_cpu.
1650 */
1651 if (cpumask_test_cpu(cpu, sched_domain_span(sd)) &&
1652 cpumask_test_cpu(prev_cpu, sched_domain_span(sd)))
1653 break;
1654 }
1655 rcu_read_unlock();
1656
1657 return target;
1658}
1659
1660/*
1661 * sched_balance_self: balance the current task (running on cpu) in domains
1662 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1663 * SD_BALANCE_EXEC.
1664 *
1665 * Balance, ie. select the least loaded group.
1666 *
1667 * Returns the target CPU number, or the same CPU if no balancing is needed.
1668 *
1669 * preempt must be disabled.
1670 */
1671static int
1672select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
1673{
1674 struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
1675 int cpu = smp_processor_id();
1676 int prev_cpu = task_cpu(p);
1677 int new_cpu = cpu;
1678 int want_affine = 0;
1679 int want_sd = 1;
1680 int sync = wake_flags & WF_SYNC;
1681
1682 if (sd_flag & SD_BALANCE_WAKE) {
1683 if (cpumask_test_cpu(cpu, &p->cpus_allowed))
1684 want_affine = 1;
1685 new_cpu = prev_cpu;
1686 }
1687
1688 rcu_read_lock();
1689 for_each_domain(cpu, tmp) {
1690 if (!(tmp->flags & SD_LOAD_BALANCE))
1691 continue;
1692
1693 /*
1694 * If power savings logic is enabled for a domain, see if we
1695 * are not overloaded, if so, don't balance wider.
1696 */
1697 if (tmp->flags & (SD_POWERSAVINGS_BALANCE|SD_PREFER_LOCAL)) {
1698 unsigned long power = 0;
1699 unsigned long nr_running = 0;
1700 unsigned long capacity;
1701 int i;
1702
1703 for_each_cpu(i, sched_domain_span(tmp)) {
1704 power += power_of(i);
1705 nr_running += cpu_rq(i)->cfs.nr_running;
1706 }
1707
1708 capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE);
1709
1710 if (tmp->flags & SD_POWERSAVINGS_BALANCE)
1711 nr_running /= 2;
1712
1713 if (nr_running < capacity)
1714 want_sd = 0;
1715 }
1716
1717 /*
1718 * If both cpu and prev_cpu are part of this domain,
1719 * cpu is a valid SD_WAKE_AFFINE target.
1720 */
1721 if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
1722 cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
1723 affine_sd = tmp;
1724 want_affine = 0;
1725 }
1726
1727 if (!want_sd && !want_affine)
1728 break;
1729
1730 if (!(tmp->flags & sd_flag))
1731 continue;
1732
1733 if (want_sd)
1734 sd = tmp;
1735 }
1736
1737 if (affine_sd) {
1738 if (cpu == prev_cpu || wake_affine(affine_sd, p, sync))
1739 prev_cpu = cpu;
1740
1741 new_cpu = select_idle_sibling(p, prev_cpu);
1742 goto unlock;
1743 }
1744
1745 while (sd) {
1746 int load_idx = sd->forkexec_idx;
1747 struct sched_group *group;
1748 int weight;
1749
1750 if (!(sd->flags & sd_flag)) {
1751 sd = sd->child;
1752 continue;
1753 }
1754
1755 if (sd_flag & SD_BALANCE_WAKE)
1756 load_idx = sd->wake_idx;
1757
1758 group = find_idlest_group(sd, p, cpu, load_idx);
1759 if (!group) {
1760 sd = sd->child;
1761 continue;
1762 }
1763
1764 new_cpu = find_idlest_cpu(group, p, cpu);
1765 if (new_cpu == -1 || new_cpu == cpu) {
1766 /* Now try balancing at a lower domain level of cpu */
1767 sd = sd->child;
1768 continue;
1769 }
1770
1771 /* Now try balancing at a lower domain level of new_cpu */
1772 cpu = new_cpu;
1773 weight = sd->span_weight;
1774 sd = NULL;
1775 for_each_domain(cpu, tmp) {
1776 if (weight <= tmp->span_weight)
1777 break;
1778 if (tmp->flags & sd_flag)
1779 sd = tmp;
1780 }
1781 /* while loop will break here if sd == NULL */
1782 }
1783unlock:
1784 rcu_read_unlock();
1785
1786 return new_cpu;
1787}
1788#endif /* CONFIG_SMP */
1789
1790static unsigned long
1791wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
1792{
1793 unsigned long gran = sysctl_sched_wakeup_granularity;
1794
1795 /*
1796 * Since its curr running now, convert the gran from real-time
1797 * to virtual-time in his units.
1798 *
1799 * By using 'se' instead of 'curr' we penalize light tasks, so
1800 * they get preempted easier. That is, if 'se' < 'curr' then
1801 * the resulting gran will be larger, therefore penalizing the
1802 * lighter, if otoh 'se' > 'curr' then the resulting gran will
1803 * be smaller, again penalizing the lighter task.
1804 *
1805 * This is especially important for buddies when the leftmost
1806 * task is higher priority than the buddy.
1807 */
1808 return calc_delta_fair(gran, se);
1809}
1810
1811/*
1812 * Should 'se' preempt 'curr'.
1813 *
1814 * |s1
1815 * |s2
1816 * |s3
1817 * g
1818 * |<--->|c
1819 *
1820 * w(c, s1) = -1
1821 * w(c, s2) = 0
1822 * w(c, s3) = 1
1823 *
1824 */
1825static int
1826wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
1827{
1828 s64 gran, vdiff = curr->vruntime - se->vruntime;
1829
1830 if (vdiff <= 0)
1831 return -1;
1832
1833 gran = wakeup_gran(curr, se);
1834 if (vdiff > gran)
1835 return 1;
1836
1837 return 0;
1838}
1839
1840static void set_last_buddy(struct sched_entity *se)
1841{
1842 if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
1843 return;
1844
1845 for_each_sched_entity(se)
1846 cfs_rq_of(se)->last = se;
1847}
1848
1849static void set_next_buddy(struct sched_entity *se)
1850{
1851 if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
1852 return;
1853
1854 for_each_sched_entity(se)
1855 cfs_rq_of(se)->next = se;
1856}
1857
1858static void set_skip_buddy(struct sched_entity *se)
1859{
1860 for_each_sched_entity(se)
1861 cfs_rq_of(se)->skip = se;
1862}
1863
1864/*
1865 * Preempt the current task with a newly woken task if needed:
1866 */
1867static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1868{
1869 struct task_struct *curr = rq->curr;
1870 struct sched_entity *se = &curr->se, *pse = &p->se;
1871 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
1872 int scale = cfs_rq->nr_running >= sched_nr_latency;
1873 int next_buddy_marked = 0;
1874
1875 if (unlikely(se == pse))
1876 return;
1877
1878 if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
1879 set_next_buddy(pse);
1880 next_buddy_marked = 1;
1881 }
1882
1883 /*
1884 * We can come here with TIF_NEED_RESCHED already set from new task
1885 * wake up path.
1886 */
1887 if (test_tsk_need_resched(curr))
1888 return;
1889
1890 /* Idle tasks are by definition preempted by non-idle tasks. */
1891 if (unlikely(curr->policy == SCHED_IDLE) &&
1892 likely(p->policy != SCHED_IDLE))
1893 goto preempt;
1894
1895 /*
1896 * Batch and idle tasks do not preempt non-idle tasks (their preemption
1897 * is driven by the tick):
1898 */
1899 if (unlikely(p->policy != SCHED_NORMAL))
1900 return;
1901
1902
1903 if (!sched_feat(WAKEUP_PREEMPT))
1904 return;
1905
1906 find_matching_se(&se, &pse);
1907 update_curr(cfs_rq_of(se));
1908 BUG_ON(!pse);
1909 if (wakeup_preempt_entity(se, pse) == 1) {
1910 /*
1911 * Bias pick_next to pick the sched entity that is
1912 * triggering this preemption.
1913 */
1914 if (!next_buddy_marked)
1915 set_next_buddy(pse);
1916 goto preempt;
1917 }
1918
1919 return;
1920
1921preempt:
1922 resched_task(curr);
1923 /*
1924 * Only set the backward buddy when the current task is still
1925 * on the rq. This can happen when a wakeup gets interleaved
1926 * with schedule on the ->pre_schedule() or idle_balance()
1927 * point, either of which can * drop the rq lock.
1928 *
1929 * Also, during early boot the idle thread is in the fair class,
1930 * for obvious reasons its a bad idea to schedule back to it.
1931 */
1932 if (unlikely(!se->on_rq || curr == rq->idle))
1933 return;
1934
1935 if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
1936 set_last_buddy(se);
1937}
1938
1939static struct task_struct *pick_next_task_fair(struct rq *rq)
1940{
1941 struct task_struct *p;
1942 struct cfs_rq *cfs_rq = &rq->cfs;
1943 struct sched_entity *se;
1944
1945 if (!cfs_rq->nr_running)
1946 return NULL;
1947
1948 do {
1949 se = pick_next_entity(cfs_rq);
1950 set_next_entity(cfs_rq, se);
1951 cfs_rq = group_cfs_rq(se);
1952 } while (cfs_rq);
1953
1954 p = task_of(se);
1955 hrtick_start_fair(rq, p);
1956
1957 return p;
1958}
1959
1960/*
1961 * Account for a descheduled task:
1962 */
1963static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
1964{
1965 struct sched_entity *se = &prev->se;
1966 struct cfs_rq *cfs_rq;
1967
1968 for_each_sched_entity(se) {
1969 cfs_rq = cfs_rq_of(se);
1970 put_prev_entity(cfs_rq, se);
1971 }
1972}
1973
1974/*
1975 * sched_yield() is very simple
1976 *
1977 * The magic of dealing with the ->skip buddy is in pick_next_entity.
1978 */
1979static void yield_task_fair(struct rq *rq)
1980{
1981 struct task_struct *curr = rq->curr;
1982 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
1983 struct sched_entity *se = &curr->se;
1984
1985 /*
1986 * Are we the only task in the tree?
1987 */
1988 if (unlikely(rq->nr_running == 1))
1989 return;
1990
1991 clear_buddies(cfs_rq, se);
1992
1993 if (curr->policy != SCHED_BATCH) {
1994 update_rq_clock(rq);
1995 /*
1996 * Update run-time statistics of the 'current'.
1997 */
1998 update_curr(cfs_rq);
1999 }
2000
2001 set_skip_buddy(se);
2002}
2003
2004static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt)
2005{
2006 struct sched_entity *se = &p->se;
2007
2008 if (!se->on_rq)
2009 return false;
2010
2011 /* Tell the scheduler that we'd really like pse to run next. */
2012 set_next_buddy(se);
2013
2014 yield_task_fair(rq);
2015
2016 return true;
2017}
2018
2019#ifdef CONFIG_SMP
2020/**************************************************
2021 * Fair scheduling class load-balancing methods:
2022 */
2023
2024/*
2025 * pull_task - move a task from a remote runqueue to the local runqueue.
2026 * Both runqueues must be locked.
2027 */
2028static void pull_task(struct rq *src_rq, struct task_struct *p,
2029 struct rq *this_rq, int this_cpu)
2030{
2031 deactivate_task(src_rq, p, 0);
2032 set_task_cpu(p, this_cpu);
2033 activate_task(this_rq, p, 0);
2034 check_preempt_curr(this_rq, p, 0);
2035}
2036
2037/*
2038 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2039 */
2040static
2041int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
2042 struct sched_domain *sd, enum cpu_idle_type idle,
2043 int *all_pinned)
2044{
2045 int tsk_cache_hot = 0;
2046 /*
2047 * We do not migrate tasks that are:
2048 * 1) running (obviously), or
2049 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2050 * 3) are cache-hot on their current CPU.
2051 */
2052 if (!cpumask_test_cpu(this_cpu, &p->cpus_allowed)) {
2053 schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
2054 return 0;
2055 }
2056 *all_pinned = 0;
2057
2058 if (task_running(rq, p)) {
2059 schedstat_inc(p, se.statistics.nr_failed_migrations_running);
2060 return 0;
2061 }
2062
2063 /*
2064 * Aggressive migration if:
2065 * 1) task is cache cold, or
2066 * 2) too many balance attempts have failed.
2067 */
2068
2069 tsk_cache_hot = task_hot(p, rq->clock_task, sd);
2070 if (!tsk_cache_hot ||
2071 sd->nr_balance_failed > sd->cache_nice_tries) {
2072#ifdef CONFIG_SCHEDSTATS
2073 if (tsk_cache_hot) {
2074 schedstat_inc(sd, lb_hot_gained[idle]);
2075 schedstat_inc(p, se.statistics.nr_forced_migrations);
2076 }
2077#endif
2078 return 1;
2079 }
2080
2081 if (tsk_cache_hot) {
2082 schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
2083 return 0;
2084 }
2085 return 1;
2086}
2087
2088/*
2089 * move_one_task tries to move exactly one task from busiest to this_rq, as
2090 * part of active balancing operations within "domain".
2091 * Returns 1 if successful and 0 otherwise.
2092 *
2093 * Called with both runqueues locked.
2094 */
2095static int
2096move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
2097 struct sched_domain *sd, enum cpu_idle_type idle)
2098{
2099 struct task_struct *p, *n;
2100 struct cfs_rq *cfs_rq;
2101 int pinned = 0;
2102
2103 for_each_leaf_cfs_rq(busiest, cfs_rq) {
2104 list_for_each_entry_safe(p, n, &cfs_rq->tasks, se.group_node) {
2105
2106 if (!can_migrate_task(p, busiest, this_cpu,
2107 sd, idle, &pinned))
2108 continue;
2109
2110 pull_task(busiest, p, this_rq, this_cpu);
2111 /*
2112 * Right now, this is only the second place pull_task()
2113 * is called, so we can safely collect pull_task()
2114 * stats here rather than inside pull_task().
2115 */
2116 schedstat_inc(sd, lb_gained[idle]);
2117 return 1;
2118 }
2119 }
2120
2121 return 0;
2122}
2123
2124static unsigned long
2125balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
2126 unsigned long max_load_move, struct sched_domain *sd,
2127 enum cpu_idle_type idle, int *all_pinned,
2128 struct cfs_rq *busiest_cfs_rq)
2129{
2130 int loops = 0, pulled = 0;
2131 long rem_load_move = max_load_move;
2132 struct task_struct *p, *n;
2133
2134 if (max_load_move == 0)
2135 goto out;
2136
2137 list_for_each_entry_safe(p, n, &busiest_cfs_rq->tasks, se.group_node) {
2138 if (loops++ > sysctl_sched_nr_migrate)
2139 break;
2140
2141 if ((p->se.load.weight >> 1) > rem_load_move ||
2142 !can_migrate_task(p, busiest, this_cpu, sd, idle,
2143 all_pinned))
2144 continue;
2145
2146 pull_task(busiest, p, this_rq, this_cpu);
2147 pulled++;
2148 rem_load_move -= p->se.load.weight;
2149
2150#ifdef CONFIG_PREEMPT
2151 /*
2152 * NEWIDLE balancing is a source of latency, so preemptible
2153 * kernels will stop after the first task is pulled to minimize
2154 * the critical section.
2155 */
2156 if (idle == CPU_NEWLY_IDLE)
2157 break;
2158#endif
2159
2160 /*
2161 * We only want to steal up to the prescribed amount of
2162 * weighted load.
2163 */
2164 if (rem_load_move <= 0)
2165 break;
2166 }
2167out:
2168 /*
2169 * Right now, this is one of only two places pull_task() is called,
2170 * so we can safely collect pull_task() stats here rather than
2171 * inside pull_task().
2172 */
2173 schedstat_add(sd, lb_gained[idle], pulled);
2174
2175 return max_load_move - rem_load_move;
2176}
2177
2178#ifdef CONFIG_FAIR_GROUP_SCHED
2179/*
2180 * update tg->load_weight by folding this cpu's load_avg
2181 */
2182static int update_shares_cpu(struct task_group *tg, int cpu)
2183{
2184 struct cfs_rq *cfs_rq;
2185 unsigned long flags;
2186 struct rq *rq;
2187
2188 if (!tg->se[cpu])
2189 return 0;
2190
2191 rq = cpu_rq(cpu);
2192 cfs_rq = tg->cfs_rq[cpu];
2193
2194 raw_spin_lock_irqsave(&rq->lock, flags);
2195
2196 update_rq_clock(rq);
2197 update_cfs_load(cfs_rq, 1);
2198
2199 /*
2200 * We need to update shares after updating tg->load_weight in
2201 * order to adjust the weight of groups with long running tasks.
2202 */
2203 update_cfs_shares(cfs_rq);
2204
2205 raw_spin_unlock_irqrestore(&rq->lock, flags);
2206
2207 return 0;
2208}
2209
2210static void update_shares(int cpu)
2211{
2212 struct cfs_rq *cfs_rq;
2213 struct rq *rq = cpu_rq(cpu);
2214
2215 rcu_read_lock();
2216 /*
2217 * Iterates the task_group tree in a bottom up fashion, see
2218 * list_add_leaf_cfs_rq() for details.
2219 */
2220 for_each_leaf_cfs_rq(rq, cfs_rq)
2221 update_shares_cpu(cfs_rq->tg, cpu);
2222 rcu_read_unlock();
2223}
2224
2225/*
2226 * Compute the cpu's hierarchical load factor for each task group.
2227 * This needs to be done in a top-down fashion because the load of a child
2228 * group is a fraction of its parents load.
2229 */
2230static int tg_load_down(struct task_group *tg, void *data)
2231{
2232 unsigned long load;
2233 long cpu = (long)data;
2234
2235 if (!tg->parent) {
2236 load = cpu_rq(cpu)->load.weight;
2237 } else {
2238 load = tg->parent->cfs_rq[cpu]->h_load;
2239 load *= tg->se[cpu]->load.weight;
2240 load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
2241 }
2242
2243 tg->cfs_rq[cpu]->h_load = load;
2244
2245 return 0;
2246}
2247
2248static void update_h_load(long cpu)
2249{
2250 walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
2251}
2252
2253static unsigned long
2254load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
2255 unsigned long max_load_move,
2256 struct sched_domain *sd, enum cpu_idle_type idle,
2257 int *all_pinned)
2258{
2259 long rem_load_move = max_load_move;
2260 struct cfs_rq *busiest_cfs_rq;
2261
2262 rcu_read_lock();
2263 update_h_load(cpu_of(busiest));
2264
2265 for_each_leaf_cfs_rq(busiest, busiest_cfs_rq) {
2266 unsigned long busiest_h_load = busiest_cfs_rq->h_load;
2267 unsigned long busiest_weight = busiest_cfs_rq->load.weight;
2268 u64 rem_load, moved_load;
2269
2270 /*
2271 * empty group
2272 */
2273 if (!busiest_cfs_rq->task_weight)
2274 continue;
2275
2276 rem_load = (u64)rem_load_move * busiest_weight;
2277 rem_load = div_u64(rem_load, busiest_h_load + 1);
2278
2279 moved_load = balance_tasks(this_rq, this_cpu, busiest,
2280 rem_load, sd, idle, all_pinned,
2281 busiest_cfs_rq);
2282
2283 if (!moved_load)
2284 continue;
2285
2286 moved_load *= busiest_h_load;
2287 moved_load = div_u64(moved_load, busiest_weight + 1);
2288
2289 rem_load_move -= moved_load;
2290 if (rem_load_move < 0)
2291 break;
2292 }
2293 rcu_read_unlock();
2294
2295 return max_load_move - rem_load_move;
2296}
2297#else
2298static inline void update_shares(int cpu)
2299{
2300}
2301
2302static unsigned long
2303load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
2304 unsigned long max_load_move,
2305 struct sched_domain *sd, enum cpu_idle_type idle,
2306 int *all_pinned)
2307{
2308 return balance_tasks(this_rq, this_cpu, busiest,
2309 max_load_move, sd, idle, all_pinned,
2310 &busiest->cfs);
2311}
2312#endif
2313
2314/*
2315 * move_tasks tries to move up to max_load_move weighted load from busiest to
2316 * this_rq, as part of a balancing operation within domain "sd".
2317 * Returns 1 if successful and 0 otherwise.
2318 *
2319 * Called with both runqueues locked.
2320 */
2321static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
2322 unsigned long max_load_move,
2323 struct sched_domain *sd, enum cpu_idle_type idle,
2324 int *all_pinned)
2325{
2326 unsigned long total_load_moved = 0, load_moved;
2327
2328 do {
2329 load_moved = load_balance_fair(this_rq, this_cpu, busiest,
2330 max_load_move - total_load_moved,
2331 sd, idle, all_pinned);
2332
2333 total_load_moved += load_moved;
2334
2335#ifdef CONFIG_PREEMPT
2336 /*
2337 * NEWIDLE balancing is a source of latency, so preemptible
2338 * kernels will stop after the first task is pulled to minimize
2339 * the critical section.
2340 */
2341 if (idle == CPU_NEWLY_IDLE && this_rq->nr_running)
2342 break;
2343
2344 if (raw_spin_is_contended(&this_rq->lock) ||
2345 raw_spin_is_contended(&busiest->lock))
2346 break;
2347#endif
2348 } while (load_moved && max_load_move > total_load_moved);
2349
2350 return total_load_moved > 0;
2351}
2352
2353/********** Helpers for find_busiest_group ************************/
2354/*
2355 * sd_lb_stats - Structure to store the statistics of a sched_domain
2356 * during load balancing.
2357 */
2358struct sd_lb_stats {
2359 struct sched_group *busiest; /* Busiest group in this sd */
2360 struct sched_group *this; /* Local group in this sd */
2361 unsigned long total_load; /* Total load of all groups in sd */
2362 unsigned long total_pwr; /* Total power of all groups in sd */
2363 unsigned long avg_load; /* Average load across all groups in sd */
2364
2365 /** Statistics of this group */
2366 unsigned long this_load;
2367 unsigned long this_load_per_task;
2368 unsigned long this_nr_running;
2369 unsigned long this_has_capacity;
2370 unsigned int this_idle_cpus;
2371
2372 /* Statistics of the busiest group */
2373 unsigned int busiest_idle_cpus;
2374 unsigned long max_load;
2375 unsigned long busiest_load_per_task;
2376 unsigned long busiest_nr_running;
2377 unsigned long busiest_group_capacity;
2378 unsigned long busiest_has_capacity;
2379 unsigned int busiest_group_weight;
2380
2381 int group_imb; /* Is there imbalance in this sd */
2382#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2383 int power_savings_balance; /* Is powersave balance needed for this sd */
2384 struct sched_group *group_min; /* Least loaded group in sd */
2385 struct sched_group *group_leader; /* Group which relieves group_min */
2386 unsigned long min_load_per_task; /* load_per_task in group_min */
2387 unsigned long leader_nr_running; /* Nr running of group_leader */
2388 unsigned long min_nr_running; /* Nr running of group_min */
2389#endif
2390};
2391
2392/*
2393 * sg_lb_stats - stats of a sched_group required for load_balancing
2394 */
2395struct sg_lb_stats {
2396 unsigned long avg_load; /*Avg load across the CPUs of the group */
2397 unsigned long group_load; /* Total load over the CPUs of the group */
2398 unsigned long sum_nr_running; /* Nr tasks running in the group */
2399 unsigned long sum_weighted_load; /* Weighted load of group's tasks */
2400 unsigned long group_capacity;
2401 unsigned long idle_cpus;
2402 unsigned long group_weight;
2403 int group_imb; /* Is there an imbalance in the group ? */
2404 int group_has_capacity; /* Is there extra capacity in the group? */
2405};
2406
2407/**
2408 * group_first_cpu - Returns the first cpu in the cpumask of a sched_group.
2409 * @group: The group whose first cpu is to be returned.
2410 */
2411static inline unsigned int group_first_cpu(struct sched_group *group)
2412{
2413 return cpumask_first(sched_group_cpus(group));
2414}
2415
2416/**
2417 * get_sd_load_idx - Obtain the load index for a given sched domain.
2418 * @sd: The sched_domain whose load_idx is to be obtained.
2419 * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
2420 */
2421static inline int get_sd_load_idx(struct sched_domain *sd,
2422 enum cpu_idle_type idle)
2423{
2424 int load_idx;
2425
2426 switch (idle) {
2427 case CPU_NOT_IDLE:
2428 load_idx = sd->busy_idx;
2429 break;
2430
2431 case CPU_NEWLY_IDLE:
2432 load_idx = sd->newidle_idx;
2433 break;
2434 default:
2435 load_idx = sd->idle_idx;
2436 break;
2437 }
2438
2439 return load_idx;
2440}
2441
2442
2443#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2444/**
2445 * init_sd_power_savings_stats - Initialize power savings statistics for
2446 * the given sched_domain, during load balancing.
2447 *
2448 * @sd: Sched domain whose power-savings statistics are to be initialized.
2449 * @sds: Variable containing the statistics for sd.
2450 * @idle: Idle status of the CPU at which we're performing load-balancing.
2451 */
2452static inline void init_sd_power_savings_stats(struct sched_domain *sd,
2453 struct sd_lb_stats *sds, enum cpu_idle_type idle)
2454{
2455 /*
2456 * Busy processors will not participate in power savings
2457 * balance.
2458 */
2459 if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
2460 sds->power_savings_balance = 0;
2461 else {
2462 sds->power_savings_balance = 1;
2463 sds->min_nr_running = ULONG_MAX;
2464 sds->leader_nr_running = 0;
2465 }
2466}
2467
2468/**
2469 * update_sd_power_savings_stats - Update the power saving stats for a
2470 * sched_domain while performing load balancing.
2471 *
2472 * @group: sched_group belonging to the sched_domain under consideration.
2473 * @sds: Variable containing the statistics of the sched_domain
2474 * @local_group: Does group contain the CPU for which we're performing
2475 * load balancing ?
2476 * @sgs: Variable containing the statistics of the group.
2477 */
2478static inline void update_sd_power_savings_stats(struct sched_group *group,
2479 struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
2480{
2481
2482 if (!sds->power_savings_balance)
2483 return;
2484
2485 /*
2486 * If the local group is idle or completely loaded
2487 * no need to do power savings balance at this domain
2488 */
2489 if (local_group && (sds->this_nr_running >= sgs->group_capacity ||
2490 !sds->this_nr_running))
2491 sds->power_savings_balance = 0;
2492
2493 /*
2494 * If a group is already running at full capacity or idle,
2495 * don't include that group in power savings calculations
2496 */
2497 if (!sds->power_savings_balance ||
2498 sgs->sum_nr_running >= sgs->group_capacity ||
2499 !sgs->sum_nr_running)
2500 return;
2501
2502 /*
2503 * Calculate the group which has the least non-idle load.
2504 * This is the group from where we need to pick up the load
2505 * for saving power
2506 */
2507 if ((sgs->sum_nr_running < sds->min_nr_running) ||
2508 (sgs->sum_nr_running == sds->min_nr_running &&
2509 group_first_cpu(group) > group_first_cpu(sds->group_min))) {
2510 sds->group_min = group;
2511 sds->min_nr_running = sgs->sum_nr_running;
2512 sds->min_load_per_task = sgs->sum_weighted_load /
2513 sgs->sum_nr_running;
2514 }
2515
2516 /*
2517 * Calculate the group which is almost near its
2518 * capacity but still has some space to pick up some load
2519 * from other group and save more power
2520 */
2521 if (sgs->sum_nr_running + 1 > sgs->group_capacity)
2522 return;
2523
2524 if (sgs->sum_nr_running > sds->leader_nr_running ||
2525 (sgs->sum_nr_running == sds->leader_nr_running &&
2526 group_first_cpu(group) < group_first_cpu(sds->group_leader))) {
2527 sds->group_leader = group;
2528 sds->leader_nr_running = sgs->sum_nr_running;
2529 }
2530}
2531
2532/**
2533 * check_power_save_busiest_group - see if there is potential for some power-savings balance
2534 * @sds: Variable containing the statistics of the sched_domain
2535 * under consideration.
2536 * @this_cpu: Cpu at which we're currently performing load-balancing.
2537 * @imbalance: Variable to store the imbalance.
2538 *
2539 * Description:
2540 * Check if we have potential to perform some power-savings balance.
2541 * If yes, set the busiest group to be the least loaded group in the
2542 * sched_domain, so that it's CPUs can be put to idle.
2543 *
2544 * Returns 1 if there is potential to perform power-savings balance.
2545 * Else returns 0.
2546 */
2547static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
2548 int this_cpu, unsigned long *imbalance)
2549{
2550 if (!sds->power_savings_balance)
2551 return 0;
2552
2553 if (sds->this != sds->group_leader ||
2554 sds->group_leader == sds->group_min)
2555 return 0;
2556
2557 *imbalance = sds->min_load_per_task;
2558 sds->busiest = sds->group_min;
2559
2560 return 1;
2561
2562}
2563#else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
2564static inline void init_sd_power_savings_stats(struct sched_domain *sd,
2565 struct sd_lb_stats *sds, enum cpu_idle_type idle)
2566{
2567 return;
2568}
2569
2570static inline void update_sd_power_savings_stats(struct sched_group *group,
2571 struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
2572{
2573 return;
2574}
2575
2576static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
2577 int this_cpu, unsigned long *imbalance)
2578{
2579 return 0;
2580}
2581#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
2582
2583
2584unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
2585{
2586 return SCHED_POWER_SCALE;
2587}
2588
2589unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
2590{
2591 return default_scale_freq_power(sd, cpu);
2592}
2593
2594unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
2595{
2596 unsigned long weight = sd->span_weight;
2597 unsigned long smt_gain = sd->smt_gain;
2598
2599 smt_gain /= weight;
2600
2601 return smt_gain;
2602}
2603
2604unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
2605{
2606 return default_scale_smt_power(sd, cpu);
2607}
2608
2609unsigned long scale_rt_power(int cpu)
2610{
2611 struct rq *rq = cpu_rq(cpu);
2612 u64 total, available;
2613
2614 total = sched_avg_period() + (rq->clock - rq->age_stamp);
2615
2616 if (unlikely(total < rq->rt_avg)) {
2617 /* Ensures that power won't end up being negative */
2618 available = 0;
2619 } else {
2620 available = total - rq->rt_avg;
2621 }
2622
2623 if (unlikely((s64)total < SCHED_POWER_SCALE))
2624 total = SCHED_POWER_SCALE;
2625
2626 total >>= SCHED_POWER_SHIFT;
2627
2628 return div_u64(available, total);
2629}
2630
2631static void update_cpu_power(struct sched_domain *sd, int cpu)
2632{
2633 unsigned long weight = sd->span_weight;
2634 unsigned long power = SCHED_POWER_SCALE;
2635 struct sched_group *sdg = sd->groups;
2636
2637 if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
2638 if (sched_feat(ARCH_POWER))
2639 power *= arch_scale_smt_power(sd, cpu);
2640 else
2641 power *= default_scale_smt_power(sd, cpu);
2642
2643 power >>= SCHED_POWER_SHIFT;
2644 }
2645
2646 sdg->sgp->power_orig = power;
2647
2648 if (sched_feat(ARCH_POWER))
2649 power *= arch_scale_freq_power(sd, cpu);
2650 else
2651 power *= default_scale_freq_power(sd, cpu);
2652
2653 power >>= SCHED_POWER_SHIFT;
2654
2655 power *= scale_rt_power(cpu);
2656 power >>= SCHED_POWER_SHIFT;
2657
2658 if (!power)
2659 power = 1;
2660
2661 cpu_rq(cpu)->cpu_power = power;
2662 sdg->sgp->power = power;
2663}
2664
2665static void update_group_power(struct sched_domain *sd, int cpu)
2666{
2667 struct sched_domain *child = sd->child;
2668 struct sched_group *group, *sdg = sd->groups;
2669 unsigned long power;
2670
2671 if (!child) {
2672 update_cpu_power(sd, cpu);
2673 return;
2674 }
2675
2676 power = 0;
2677
2678 group = child->groups;
2679 do {
2680 power += group->sgp->power;
2681 group = group->next;
2682 } while (group != child->groups);
2683
2684 sdg->sgp->power = power;
2685}
2686
2687/*
2688 * Try and fix up capacity for tiny siblings, this is needed when
2689 * things like SD_ASYM_PACKING need f_b_g to select another sibling
2690 * which on its own isn't powerful enough.
2691 *
2692 * See update_sd_pick_busiest() and check_asym_packing().
2693 */
2694static inline int
2695fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
2696{
2697 /*
2698 * Only siblings can have significantly less than SCHED_POWER_SCALE
2699 */
2700 if (!(sd->flags & SD_SHARE_CPUPOWER))
2701 return 0;
2702
2703 /*
2704 * If ~90% of the cpu_power is still there, we're good.
2705 */
2706 if (group->sgp->power * 32 > group->sgp->power_orig * 29)
2707 return 1;
2708
2709 return 0;
2710}
2711
2712/**
2713 * update_sg_lb_stats - Update sched_group's statistics for load balancing.
2714 * @sd: The sched_domain whose statistics are to be updated.
2715 * @group: sched_group whose statistics are to be updated.
2716 * @this_cpu: Cpu for which load balance is currently performed.
2717 * @idle: Idle status of this_cpu
2718 * @load_idx: Load index of sched_domain of this_cpu for load calc.
2719 * @local_group: Does group contain this_cpu.
2720 * @cpus: Set of cpus considered for load balancing.
2721 * @balance: Should we balance.
2722 * @sgs: variable to hold the statistics for this group.
2723 */
2724static inline void update_sg_lb_stats(struct sched_domain *sd,
2725 struct sched_group *group, int this_cpu,
2726 enum cpu_idle_type idle, int load_idx,
2727 int local_group, const struct cpumask *cpus,
2728 int *balance, struct sg_lb_stats *sgs)
2729{
2730 unsigned long load, max_cpu_load, min_cpu_load, max_nr_running;
2731 int i;
2732 unsigned int balance_cpu = -1, first_idle_cpu = 0;
2733 unsigned long avg_load_per_task = 0;
2734
2735 if (local_group)
2736 balance_cpu = group_first_cpu(group);
2737
2738 /* Tally up the load of all CPUs in the group */
2739 max_cpu_load = 0;
2740 min_cpu_load = ~0UL;
2741 max_nr_running = 0;
2742
2743 for_each_cpu_and(i, sched_group_cpus(group), cpus) {
2744 struct rq *rq = cpu_rq(i);
2745
2746 /* Bias balancing toward cpus of our domain */
2747 if (local_group) {
2748 if (idle_cpu(i) && !first_idle_cpu) {
2749 first_idle_cpu = 1;
2750 balance_cpu = i;
2751 }
2752
2753 load = target_load(i, load_idx);
2754 } else {
2755 load = source_load(i, load_idx);
2756 if (load > max_cpu_load) {
2757 max_cpu_load = load;
2758 max_nr_running = rq->nr_running;
2759 }
2760 if (min_cpu_load > load)
2761 min_cpu_load = load;
2762 }
2763
2764 sgs->group_load += load;
2765 sgs->sum_nr_running += rq->nr_running;
2766 sgs->sum_weighted_load += weighted_cpuload(i);
2767 if (idle_cpu(i))
2768 sgs->idle_cpus++;
2769 }
2770
2771 /*
2772 * First idle cpu or the first cpu(busiest) in this sched group
2773 * is eligible for doing load balancing at this and above
2774 * domains. In the newly idle case, we will allow all the cpu's
2775 * to do the newly idle load balance.
2776 */
2777 if (idle != CPU_NEWLY_IDLE && local_group) {
2778 if (balance_cpu != this_cpu) {
2779 *balance = 0;
2780 return;
2781 }
2782 update_group_power(sd, this_cpu);
2783 }
2784
2785 /* Adjust by relative CPU power of the group */
2786 sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;
2787
2788 /*
2789 * Consider the group unbalanced when the imbalance is larger
2790 * than the average weight of a task.
2791 *
2792 * APZ: with cgroup the avg task weight can vary wildly and
2793 * might not be a suitable number - should we keep a
2794 * normalized nr_running number somewhere that negates
2795 * the hierarchy?
2796 */
2797 if (sgs->sum_nr_running)
2798 avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
2799
2800 if ((max_cpu_load - min_cpu_load) >= avg_load_per_task && max_nr_running > 1)
2801 sgs->group_imb = 1;
2802
2803 sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
2804 SCHED_POWER_SCALE);
2805 if (!sgs->group_capacity)
2806 sgs->group_capacity = fix_small_capacity(sd, group);
2807 sgs->group_weight = group->group_weight;
2808
2809 if (sgs->group_capacity > sgs->sum_nr_running)
2810 sgs->group_has_capacity = 1;
2811}
2812
2813/**
2814 * update_sd_pick_busiest - return 1 on busiest group
2815 * @sd: sched_domain whose statistics are to be checked
2816 * @sds: sched_domain statistics
2817 * @sg: sched_group candidate to be checked for being the busiest
2818 * @sgs: sched_group statistics
2819 * @this_cpu: the current cpu
2820 *
2821 * Determine if @sg is a busier group than the previously selected
2822 * busiest group.
2823 */
2824static bool update_sd_pick_busiest(struct sched_domain *sd,
2825 struct sd_lb_stats *sds,
2826 struct sched_group *sg,
2827 struct sg_lb_stats *sgs,
2828 int this_cpu)
2829{
2830 if (sgs->avg_load <= sds->max_load)
2831 return false;
2832
2833 if (sgs->sum_nr_running > sgs->group_capacity)
2834 return true;
2835
2836 if (sgs->group_imb)
2837 return true;
2838
2839 /*
2840 * ASYM_PACKING needs to move all the work to the lowest
2841 * numbered CPUs in the group, therefore mark all groups
2842 * higher than ourself as busy.
2843 */
2844 if ((sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running &&
2845 this_cpu < group_first_cpu(sg)) {
2846 if (!sds->busiest)
2847 return true;
2848
2849 if (group_first_cpu(sds->busiest) > group_first_cpu(sg))
2850 return true;
2851 }
2852
2853 return false;
2854}
2855
2856/**
2857 * update_sd_lb_stats - Update sched_group's statistics for load balancing.
2858 * @sd: sched_domain whose statistics are to be updated.
2859 * @this_cpu: Cpu for which load balance is currently performed.
2860 * @idle: Idle status of this_cpu
2861 * @cpus: Set of cpus considered for load balancing.
2862 * @balance: Should we balance.
2863 * @sds: variable to hold the statistics for this sched_domain.
2864 */
2865static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
2866 enum cpu_idle_type idle, const struct cpumask *cpus,
2867 int *balance, struct sd_lb_stats *sds)
2868{
2869 struct sched_domain *child = sd->child;
2870 struct sched_group *sg = sd->groups;
2871 struct sg_lb_stats sgs;
2872 int load_idx, prefer_sibling = 0;
2873
2874 if (child && child->flags & SD_PREFER_SIBLING)
2875 prefer_sibling = 1;
2876
2877 init_sd_power_savings_stats(sd, sds, idle);
2878 load_idx = get_sd_load_idx(sd, idle);
2879
2880 do {
2881 int local_group;
2882
2883 local_group = cpumask_test_cpu(this_cpu, sched_group_cpus(sg));
2884 memset(&sgs, 0, sizeof(sgs));
2885 update_sg_lb_stats(sd, sg, this_cpu, idle, load_idx,
2886 local_group, cpus, balance, &sgs);
2887
2888 if (local_group && !(*balance))
2889 return;
2890
2891 sds->total_load += sgs.group_load;
2892 sds->total_pwr += sg->sgp->power;
2893
2894 /*
2895 * In case the child domain prefers tasks go to siblings
2896 * first, lower the sg capacity to one so that we'll try
2897 * and move all the excess tasks away. We lower the capacity
2898 * of a group only if the local group has the capacity to fit
2899 * these excess tasks, i.e. nr_running < group_capacity. The
2900 * extra check prevents the case where you always pull from the
2901 * heaviest group when it is already under-utilized (possible
2902 * with a large weight task outweighs the tasks on the system).
2903 */
2904 if (prefer_sibling && !local_group && sds->this_has_capacity)
2905 sgs.group_capacity = min(sgs.group_capacity, 1UL);
2906
2907 if (local_group) {
2908 sds->this_load = sgs.avg_load;
2909 sds->this = sg;
2910 sds->this_nr_running = sgs.sum_nr_running;
2911 sds->this_load_per_task = sgs.sum_weighted_load;
2912 sds->this_has_capacity = sgs.group_has_capacity;
2913 sds->this_idle_cpus = sgs.idle_cpus;
2914 } else if (update_sd_pick_busiest(sd, sds, sg, &sgs, this_cpu)) {
2915 sds->max_load = sgs.avg_load;
2916 sds->busiest = sg;
2917 sds->busiest_nr_running = sgs.sum_nr_running;
2918 sds->busiest_idle_cpus = sgs.idle_cpus;
2919 sds->busiest_group_capacity = sgs.group_capacity;
2920 sds->busiest_load_per_task = sgs.sum_weighted_load;
2921 sds->busiest_has_capacity = sgs.group_has_capacity;
2922 sds->busiest_group_weight = sgs.group_weight;
2923 sds->group_imb = sgs.group_imb;
2924 }
2925
2926 update_sd_power_savings_stats(sg, sds, local_group, &sgs);
2927 sg = sg->next;
2928 } while (sg != sd->groups);
2929}
2930
2931int __weak arch_sd_sibling_asym_packing(void)
2932{
2933 return 0*SD_ASYM_PACKING;
2934}
2935
2936/**
2937 * check_asym_packing - Check to see if the group is packed into the
2938 * sched doman.
2939 *
2940 * This is primarily intended to used at the sibling level. Some
2941 * cores like POWER7 prefer to use lower numbered SMT threads. In the
2942 * case of POWER7, it can move to lower SMT modes only when higher
2943 * threads are idle. When in lower SMT modes, the threads will
2944 * perform better since they share less core resources. Hence when we
2945 * have idle threads, we want them to be the higher ones.
2946 *
2947 * This packing function is run on idle threads. It checks to see if
2948 * the busiest CPU in this domain (core in the P7 case) has a higher
2949 * CPU number than the packing function is being run on. Here we are
2950 * assuming lower CPU number will be equivalent to lower a SMT thread
2951 * number.
2952 *
2953 * Returns 1 when packing is required and a task should be moved to
2954 * this CPU. The amount of the imbalance is returned in *imbalance.
2955 *
2956 * @sd: The sched_domain whose packing is to be checked.
2957 * @sds: Statistics of the sched_domain which is to be packed
2958 * @this_cpu: The cpu at whose sched_domain we're performing load-balance.
2959 * @imbalance: returns amount of imbalanced due to packing.
2960 */
2961static int check_asym_packing(struct sched_domain *sd,
2962 struct sd_lb_stats *sds,
2963 int this_cpu, unsigned long *imbalance)
2964{
2965 int busiest_cpu;
2966
2967 if (!(sd->flags & SD_ASYM_PACKING))
2968 return 0;
2969
2970 if (!sds->busiest)
2971 return 0;
2972
2973 busiest_cpu = group_first_cpu(sds->busiest);
2974 if (this_cpu > busiest_cpu)
2975 return 0;
2976
2977 *imbalance = DIV_ROUND_CLOSEST(sds->max_load * sds->busiest->sgp->power,
2978 SCHED_POWER_SCALE);
2979 return 1;
2980}
2981
2982/**
2983 * fix_small_imbalance - Calculate the minor imbalance that exists
2984 * amongst the groups of a sched_domain, during
2985 * load balancing.
2986 * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
2987 * @this_cpu: The cpu at whose sched_domain we're performing load-balance.
2988 * @imbalance: Variable to store the imbalance.
2989 */
2990static inline void fix_small_imbalance(struct sd_lb_stats *sds,
2991 int this_cpu, unsigned long *imbalance)
2992{
2993 unsigned long tmp, pwr_now = 0, pwr_move = 0;
2994 unsigned int imbn = 2;
2995 unsigned long scaled_busy_load_per_task;
2996
2997 if (sds->this_nr_running) {
2998 sds->this_load_per_task /= sds->this_nr_running;
2999 if (sds->busiest_load_per_task >
3000 sds->this_load_per_task)
3001 imbn = 1;
3002 } else
3003 sds->this_load_per_task =
3004 cpu_avg_load_per_task(this_cpu);
3005
3006 scaled_busy_load_per_task = sds->busiest_load_per_task
3007 * SCHED_POWER_SCALE;
3008 scaled_busy_load_per_task /= sds->busiest->sgp->power;
3009
3010 if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
3011 (scaled_busy_load_per_task * imbn)) {
3012 *imbalance = sds->busiest_load_per_task;
3013 return;
3014 }
3015
3016 /*
3017 * OK, we don't have enough imbalance to justify moving tasks,
3018 * however we may be able to increase total CPU power used by
3019 * moving them.
3020 */
3021
3022 pwr_now += sds->busiest->sgp->power *
3023 min(sds->busiest_load_per_task, sds->max_load);
3024 pwr_now += sds->this->sgp->power *
3025 min(sds->this_load_per_task, sds->this_load);
3026 pwr_now /= SCHED_POWER_SCALE;
3027
3028 /* Amount of load we'd subtract */
3029 tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
3030 sds->busiest->sgp->power;
3031 if (sds->max_load > tmp)
3032 pwr_move += sds->busiest->sgp->power *
3033 min(sds->busiest_load_per_task, sds->max_load - tmp);
3034
3035 /* Amount of load we'd add */
3036 if (sds->max_load * sds->busiest->sgp->power <
3037 sds->busiest_load_per_task * SCHED_POWER_SCALE)
3038 tmp = (sds->max_load * sds->busiest->sgp->power) /
3039 sds->this->sgp->power;
3040 else
3041 tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
3042 sds->this->sgp->power;
3043 pwr_move += sds->this->sgp->power *
3044 min(sds->this_load_per_task, sds->this_load + tmp);
3045 pwr_move /= SCHED_POWER_SCALE;
3046
3047 /* Move if we gain throughput */
3048 if (pwr_move > pwr_now)
3049 *imbalance = sds->busiest_load_per_task;
3050}
3051
3052/**
3053 * calculate_imbalance - Calculate the amount of imbalance present within the
3054 * groups of a given sched_domain during load balance.
3055 * @sds: statistics of the sched_domain whose imbalance is to be calculated.
3056 * @this_cpu: Cpu for which currently load balance is being performed.
3057 * @imbalance: The variable to store the imbalance.
3058 */
3059static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu,
3060 unsigned long *imbalance)
3061{
3062 unsigned long max_pull, load_above_capacity = ~0UL;
3063
3064 sds->busiest_load_per_task /= sds->busiest_nr_running;
3065 if (sds->group_imb) {
3066 sds->busiest_load_per_task =
3067 min(sds->busiest_load_per_task, sds->avg_load);
3068 }
3069
3070 /*
3071 * In the presence of smp nice balancing, certain scenarios can have
3072 * max load less than avg load(as we skip the groups at or below
3073 * its cpu_power, while calculating max_load..)
3074 */
3075 if (sds->max_load < sds->avg_load) {
3076 *imbalance = 0;
3077 return fix_small_imbalance(sds, this_cpu, imbalance);
3078 }
3079
3080 if (!sds->group_imb) {
3081 /*
3082 * Don't want to pull so many tasks that a group would go idle.
3083 */
3084 load_above_capacity = (sds->busiest_nr_running -
3085 sds->busiest_group_capacity);
3086
3087 load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
3088
3089 load_above_capacity /= sds->busiest->sgp->power;
3090 }
3091
3092 /*
3093 * We're trying to get all the cpus to the average_load, so we don't
3094 * want to push ourselves above the average load, nor do we wish to
3095 * reduce the max loaded cpu below the average load. At the same time,
3096 * we also don't want to reduce the group load below the group capacity
3097 * (so that we can implement power-savings policies etc). Thus we look
3098 * for the minimum possible imbalance.
3099 * Be careful of negative numbers as they'll appear as very large values
3100 * with unsigned longs.
3101 */
3102 max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);
3103
3104 /* How much load to actually move to equalise the imbalance */
3105 *imbalance = min(max_pull * sds->busiest->sgp->power,
3106 (sds->avg_load - sds->this_load) * sds->this->sgp->power)
3107 / SCHED_POWER_SCALE;
3108
3109 /*
3110 * if *imbalance is less than the average load per runnable task
3111 * there is no guarantee that any tasks will be moved so we'll have
3112 * a think about bumping its value to force at least one task to be
3113 * moved
3114 */
3115 if (*imbalance < sds->busiest_load_per_task)
3116 return fix_small_imbalance(sds, this_cpu, imbalance);
3117
3118}
3119
3120/******* find_busiest_group() helpers end here *********************/
3121
3122/**
3123 * find_busiest_group - Returns the busiest group within the sched_domain
3124 * if there is an imbalance. If there isn't an imbalance, and
3125 * the user has opted for power-savings, it returns a group whose
3126 * CPUs can be put to idle by rebalancing those tasks elsewhere, if
3127 * such a group exists.
3128 *
3129 * Also calculates the amount of weighted load which should be moved
3130 * to restore balance.
3131 *
3132 * @sd: The sched_domain whose busiest group is to be returned.
3133 * @this_cpu: The cpu for which load balancing is currently being performed.
3134 * @imbalance: Variable which stores amount of weighted load which should
3135 * be moved to restore balance/put a group to idle.
3136 * @idle: The idle status of this_cpu.
3137 * @cpus: The set of CPUs under consideration for load-balancing.
3138 * @balance: Pointer to a variable indicating if this_cpu
3139 * is the appropriate cpu to perform load balancing at this_level.
3140 *
3141 * Returns: - the busiest group if imbalance exists.
3142 * - If no imbalance and user has opted for power-savings balance,
3143 * return the least loaded group whose CPUs can be
3144 * put to idle by rebalancing its tasks onto our group.
3145 */
3146static struct sched_group *
3147find_busiest_group(struct sched_domain *sd, int this_cpu,
3148 unsigned long *imbalance, enum cpu_idle_type idle,
3149 const struct cpumask *cpus, int *balance)
3150{
3151 struct sd_lb_stats sds;
3152
3153 memset(&sds, 0, sizeof(sds));
3154
3155 /*
3156 * Compute the various statistics relavent for load balancing at
3157 * this level.
3158 */
3159 update_sd_lb_stats(sd, this_cpu, idle, cpus, balance, &sds);
3160
3161 /*
3162 * this_cpu is not the appropriate cpu to perform load balancing at
3163 * this level.
3164 */
3165 if (!(*balance))
3166 goto ret;
3167
3168 if ((idle == CPU_IDLE || idle == CPU_NEWLY_IDLE) &&
3169 check_asym_packing(sd, &sds, this_cpu, imbalance))
3170 return sds.busiest;
3171
3172 /* There is no busy sibling group to pull tasks from */
3173 if (!sds.busiest || sds.busiest_nr_running == 0)
3174 goto out_balanced;
3175
3176 sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
3177
3178 /*
3179 * If the busiest group is imbalanced the below checks don't
3180 * work because they assumes all things are equal, which typically
3181 * isn't true due to cpus_allowed constraints and the like.
3182 */
3183 if (sds.group_imb)
3184 goto force_balance;
3185
3186 /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
3187 if (idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
3188 !sds.busiest_has_capacity)
3189 goto force_balance;
3190
3191 /*
3192 * If the local group is more busy than the selected busiest group
3193 * don't try and pull any tasks.
3194 */
3195 if (sds.this_load >= sds.max_load)
3196 goto out_balanced;
3197
3198 /*
3199 * Don't pull any tasks if this group is already above the domain
3200 * average load.
3201 */
3202 if (sds.this_load >= sds.avg_load)
3203 goto out_balanced;
3204
3205 if (idle == CPU_IDLE) {
3206 /*
3207 * This cpu is idle. If the busiest group load doesn't
3208 * have more tasks than the number of available cpu's and
3209 * there is no imbalance between this and busiest group
3210 * wrt to idle cpu's, it is balanced.
3211 */
3212 if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) &&
3213 sds.busiest_nr_running <= sds.busiest_group_weight)
3214 goto out_balanced;
3215 } else {
3216 /*
3217 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
3218 * imbalance_pct to be conservative.
3219 */
3220 if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load)
3221 goto out_balanced;
3222 }
3223
3224force_balance:
3225 /* Looks like there is an imbalance. Compute it */
3226 calculate_imbalance(&sds, this_cpu, imbalance);
3227 return sds.busiest;
3228
3229out_balanced:
3230 /*
3231 * There is no obvious imbalance. But check if we can do some balancing
3232 * to save power.
3233 */
3234 if (check_power_save_busiest_group(&sds, this_cpu, imbalance))
3235 return sds.busiest;
3236ret:
3237 *imbalance = 0;
3238 return NULL;
3239}
3240
3241/*
3242 * find_busiest_queue - find the busiest runqueue among the cpus in group.
3243 */
3244static struct rq *
3245find_busiest_queue(struct sched_domain *sd, struct sched_group *group,
3246 enum cpu_idle_type idle, unsigned long imbalance,
3247 const struct cpumask *cpus)
3248{
3249 struct rq *busiest = NULL, *rq;
3250 unsigned long max_load = 0;
3251 int i;
3252
3253 for_each_cpu(i, sched_group_cpus(group)) {
3254 unsigned long power = power_of(i);
3255 unsigned long capacity = DIV_ROUND_CLOSEST(power,
3256 SCHED_POWER_SCALE);
3257 unsigned long wl;
3258
3259 if (!capacity)
3260 capacity = fix_small_capacity(sd, group);
3261
3262 if (!cpumask_test_cpu(i, cpus))
3263 continue;
3264
3265 rq = cpu_rq(i);
3266 wl = weighted_cpuload(i);
3267
3268 /*
3269 * When comparing with imbalance, use weighted_cpuload()
3270 * which is not scaled with the cpu power.
3271 */
3272 if (capacity && rq->nr_running == 1 && wl > imbalance)
3273 continue;
3274
3275 /*
3276 * For the load comparisons with the other cpu's, consider
3277 * the weighted_cpuload() scaled with the cpu power, so that
3278 * the load can be moved away from the cpu that is potentially
3279 * running at a lower capacity.
3280 */
3281 wl = (wl * SCHED_POWER_SCALE) / power;
3282
3283 if (wl > max_load) {
3284 max_load = wl;
3285 busiest = rq;
3286 }
3287 }
3288
3289 return busiest;
3290}
3291
3292/*
3293 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
3294 * so long as it is large enough.
3295 */
3296#define MAX_PINNED_INTERVAL 512
3297
3298/* Working cpumask for load_balance and load_balance_newidle. */
3299static DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
3300
3301static int need_active_balance(struct sched_domain *sd, int idle,
3302 int busiest_cpu, int this_cpu)
3303{
3304 if (idle == CPU_NEWLY_IDLE) {
3305
3306 /*
3307 * ASYM_PACKING needs to force migrate tasks from busy but
3308 * higher numbered CPUs in order to pack all tasks in the
3309 * lowest numbered CPUs.
3310 */
3311 if ((sd->flags & SD_ASYM_PACKING) && busiest_cpu > this_cpu)
3312 return 1;
3313
3314 /*
3315 * The only task running in a non-idle cpu can be moved to this
3316 * cpu in an attempt to completely freeup the other CPU
3317 * package.
3318 *
3319 * The package power saving logic comes from
3320 * find_busiest_group(). If there are no imbalance, then
3321 * f_b_g() will return NULL. However when sched_mc={1,2} then
3322 * f_b_g() will select a group from which a running task may be
3323 * pulled to this cpu in order to make the other package idle.
3324 * If there is no opportunity to make a package idle and if
3325 * there are no imbalance, then f_b_g() will return NULL and no
3326 * action will be taken in load_balance_newidle().
3327 *
3328 * Under normal task pull operation due to imbalance, there
3329 * will be more than one task in the source run queue and
3330 * move_tasks() will succeed. ld_moved will be true and this
3331 * active balance code will not be triggered.
3332 */
3333 if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP)
3334 return 0;
3335 }
3336
3337 return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
3338}
3339
3340static int active_load_balance_cpu_stop(void *data);
3341
3342/*
3343 * Check this_cpu to ensure it is balanced within domain. Attempt to move
3344 * tasks if there is an imbalance.
3345 */
3346static int load_balance(int this_cpu, struct rq *this_rq,
3347 struct sched_domain *sd, enum cpu_idle_type idle,
3348 int *balance)
3349{
3350 int ld_moved, all_pinned = 0, active_balance = 0;
3351 struct sched_group *group;
3352 unsigned long imbalance;
3353 struct rq *busiest;
3354 unsigned long flags;
3355 struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
3356
3357 cpumask_copy(cpus, cpu_active_mask);
3358
3359 schedstat_inc(sd, lb_count[idle]);
3360
3361redo:
3362 group = find_busiest_group(sd, this_cpu, &imbalance, idle,
3363 cpus, balance);
3364
3365 if (*balance == 0)
3366 goto out_balanced;
3367
3368 if (!group) {
3369 schedstat_inc(sd, lb_nobusyg[idle]);
3370 goto out_balanced;
3371 }
3372
3373 busiest = find_busiest_queue(sd, group, idle, imbalance, cpus);
3374 if (!busiest) {
3375 schedstat_inc(sd, lb_nobusyq[idle]);
3376 goto out_balanced;
3377 }
3378
3379 BUG_ON(busiest == this_rq);
3380
3381 schedstat_add(sd, lb_imbalance[idle], imbalance);
3382
3383 ld_moved = 0;
3384 if (busiest->nr_running > 1) {
3385 /*
3386 * Attempt to move tasks. If find_busiest_group has found
3387 * an imbalance but busiest->nr_running <= 1, the group is
3388 * still unbalanced. ld_moved simply stays zero, so it is
3389 * correctly treated as an imbalance.
3390 */
3391 all_pinned = 1;
3392 local_irq_save(flags);
3393 double_rq_lock(this_rq, busiest);
3394 ld_moved = move_tasks(this_rq, this_cpu, busiest,
3395 imbalance, sd, idle, &all_pinned);
3396 double_rq_unlock(this_rq, busiest);
3397 local_irq_restore(flags);
3398
3399 /*
3400 * some other cpu did the load balance for us.
3401 */
3402 if (ld_moved && this_cpu != smp_processor_id())
3403 resched_cpu(this_cpu);
3404
3405 /* All tasks on this runqueue were pinned by CPU affinity */
3406 if (unlikely(all_pinned)) {
3407 cpumask_clear_cpu(cpu_of(busiest), cpus);
3408 if (!cpumask_empty(cpus))
3409 goto redo;
3410 goto out_balanced;
3411 }
3412 }
3413
3414 if (!ld_moved) {
3415 schedstat_inc(sd, lb_failed[idle]);
3416 /*
3417 * Increment the failure counter only on periodic balance.
3418 * We do not want newidle balance, which can be very
3419 * frequent, pollute the failure counter causing
3420 * excessive cache_hot migrations and active balances.
3421 */
3422 if (idle != CPU_NEWLY_IDLE)
3423 sd->nr_balance_failed++;
3424
3425 if (need_active_balance(sd, idle, cpu_of(busiest), this_cpu)) {
3426 raw_spin_lock_irqsave(&busiest->lock, flags);
3427
3428 /* don't kick the active_load_balance_cpu_stop,
3429 * if the curr task on busiest cpu can't be
3430 * moved to this_cpu
3431 */
3432 if (!cpumask_test_cpu(this_cpu,
3433 &busiest->curr->cpus_allowed)) {
3434 raw_spin_unlock_irqrestore(&busiest->lock,
3435 flags);
3436 all_pinned = 1;
3437 goto out_one_pinned;
3438 }
3439
3440 /*
3441 * ->active_balance synchronizes accesses to
3442 * ->active_balance_work. Once set, it's cleared
3443 * only after active load balance is finished.
3444 */
3445 if (!busiest->active_balance) {
3446 busiest->active_balance = 1;
3447 busiest->push_cpu = this_cpu;
3448 active_balance = 1;
3449 }
3450 raw_spin_unlock_irqrestore(&busiest->lock, flags);
3451
3452 if (active_balance)
3453 stop_one_cpu_nowait(cpu_of(busiest),
3454 active_load_balance_cpu_stop, busiest,
3455 &busiest->active_balance_work);
3456
3457 /*
3458 * We've kicked active balancing, reset the failure
3459 * counter.
3460 */
3461 sd->nr_balance_failed = sd->cache_nice_tries+1;
3462 }
3463 } else
3464 sd->nr_balance_failed = 0;
3465
3466 if (likely(!active_balance)) {
3467 /* We were unbalanced, so reset the balancing interval */
3468 sd->balance_interval = sd->min_interval;
3469 } else {
3470 /*
3471 * If we've begun active balancing, start to back off. This
3472 * case may not be covered by the all_pinned logic if there
3473 * is only 1 task on the busy runqueue (because we don't call
3474 * move_tasks).
3475 */
3476 if (sd->balance_interval < sd->max_interval)
3477 sd->balance_interval *= 2;
3478 }
3479
3480 goto out;
3481
3482out_balanced:
3483 schedstat_inc(sd, lb_balanced[idle]);
3484
3485 sd->nr_balance_failed = 0;
3486
3487out_one_pinned:
3488 /* tune up the balancing interval */
3489 if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
3490 (sd->balance_interval < sd->max_interval))
3491 sd->balance_interval *= 2;
3492
3493 ld_moved = 0;
3494out:
3495 return ld_moved;
3496}
3497
3498/*
3499 * idle_balance is called by schedule() if this_cpu is about to become
3500 * idle. Attempts to pull tasks from other CPUs.
3501 */
3502static void idle_balance(int this_cpu, struct rq *this_rq)
3503{
3504 struct sched_domain *sd;
3505 int pulled_task = 0;
3506 unsigned long next_balance = jiffies + HZ;
3507
3508 this_rq->idle_stamp = this_rq->clock;
3509
3510 if (this_rq->avg_idle < sysctl_sched_migration_cost)
3511 return;
3512
3513 /*
3514 * Drop the rq->lock, but keep IRQ/preempt disabled.
3515 */
3516 raw_spin_unlock(&this_rq->lock);
3517
3518 update_shares(this_cpu);
3519 rcu_read_lock();
3520 for_each_domain(this_cpu, sd) {
3521 unsigned long interval;
3522 int balance = 1;
3523
3524 if (!(sd->flags & SD_LOAD_BALANCE))
3525 continue;
3526
3527 if (sd->flags & SD_BALANCE_NEWIDLE) {
3528 /* If we've pulled tasks over stop searching: */
3529 pulled_task = load_balance(this_cpu, this_rq,
3530 sd, CPU_NEWLY_IDLE, &balance);
3531 }
3532
3533 interval = msecs_to_jiffies(sd->balance_interval);
3534 if (time_after(next_balance, sd->last_balance + interval))
3535 next_balance = sd->last_balance + interval;
3536 if (pulled_task) {
3537 this_rq->idle_stamp = 0;
3538 break;
3539 }
3540 }
3541 rcu_read_unlock();
3542
3543 raw_spin_lock(&this_rq->lock);
3544
3545 if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
3546 /*
3547 * We are going idle. next_balance may be set based on
3548 * a busy processor. So reset next_balance.
3549 */
3550 this_rq->next_balance = next_balance;
3551 }
3552}
3553
3554/*
3555 * active_load_balance_cpu_stop is run by cpu stopper. It pushes
3556 * running tasks off the busiest CPU onto idle CPUs. It requires at
3557 * least 1 task to be running on each physical CPU where possible, and
3558 * avoids physical / logical imbalances.
3559 */
3560static int active_load_balance_cpu_stop(void *data)
3561{
3562 struct rq *busiest_rq = data;
3563 int busiest_cpu = cpu_of(busiest_rq);
3564 int target_cpu = busiest_rq->push_cpu;
3565 struct rq *target_rq = cpu_rq(target_cpu);
3566 struct sched_domain *sd;
3567
3568 raw_spin_lock_irq(&busiest_rq->lock);
3569
3570 /* make sure the requested cpu hasn't gone down in the meantime */
3571 if (unlikely(busiest_cpu != smp_processor_id() ||
3572 !busiest_rq->active_balance))
3573 goto out_unlock;
3574
3575 /* Is there any task to move? */
3576 if (busiest_rq->nr_running <= 1)
3577 goto out_unlock;
3578
3579 /*
3580 * This condition is "impossible", if it occurs
3581 * we need to fix it. Originally reported by
3582 * Bjorn Helgaas on a 128-cpu setup.
3583 */
3584 BUG_ON(busiest_rq == target_rq);
3585
3586 /* move a task from busiest_rq to target_rq */
3587 double_lock_balance(busiest_rq, target_rq);
3588
3589 /* Search for an sd spanning us and the target CPU. */
3590 rcu_read_lock();
3591 for_each_domain(target_cpu, sd) {
3592 if ((sd->flags & SD_LOAD_BALANCE) &&
3593 cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
3594 break;
3595 }
3596
3597 if (likely(sd)) {
3598 schedstat_inc(sd, alb_count);
3599
3600 if (move_one_task(target_rq, target_cpu, busiest_rq,
3601 sd, CPU_IDLE))
3602 schedstat_inc(sd, alb_pushed);
3603 else
3604 schedstat_inc(sd, alb_failed);
3605 }
3606 rcu_read_unlock();
3607 double_unlock_balance(busiest_rq, target_rq);
3608out_unlock:
3609 busiest_rq->active_balance = 0;
3610 raw_spin_unlock_irq(&busiest_rq->lock);
3611 return 0;
3612}
3613
3614#ifdef CONFIG_NO_HZ
3615
3616static DEFINE_PER_CPU(struct call_single_data, remote_sched_softirq_cb);
3617
3618static void trigger_sched_softirq(void *data)
3619{
3620 raise_softirq_irqoff(SCHED_SOFTIRQ);
3621}
3622
3623static inline void init_sched_softirq_csd(struct call_single_data *csd)
3624{
3625 csd->func = trigger_sched_softirq;
3626 csd->info = NULL;
3627 csd->flags = 0;
3628 csd->priv = 0;
3629}
3630
3631/*
3632 * idle load balancing details
3633 * - One of the idle CPUs nominates itself as idle load_balancer, while
3634 * entering idle.
3635 * - This idle load balancer CPU will also go into tickless mode when
3636 * it is idle, just like all other idle CPUs
3637 * - When one of the busy CPUs notice that there may be an idle rebalancing
3638 * needed, they will kick the idle load balancer, which then does idle
3639 * load balancing for all the idle CPUs.
3640 */
3641static struct {
3642 atomic_t load_balancer;
3643 atomic_t first_pick_cpu;
3644 atomic_t second_pick_cpu;
3645 cpumask_var_t idle_cpus_mask;
3646 cpumask_var_t grp_idle_mask;
3647 unsigned long next_balance; /* in jiffy units */
3648} nohz ____cacheline_aligned;
3649
3650int get_nohz_load_balancer(void)
3651{
3652 return atomic_read(&nohz.load_balancer);
3653}
3654
3655#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
3656/**
3657 * lowest_flag_domain - Return lowest sched_domain containing flag.
3658 * @cpu: The cpu whose lowest level of sched domain is to
3659 * be returned.
3660 * @flag: The flag to check for the lowest sched_domain
3661 * for the given cpu.
3662 *
3663 * Returns the lowest sched_domain of a cpu which contains the given flag.
3664 */
3665static inline struct sched_domain *lowest_flag_domain(int cpu, int flag)
3666{
3667 struct sched_domain *sd;
3668
3669 for_each_domain(cpu, sd)
3670 if (sd && (sd->flags & flag))
3671 break;
3672
3673 return sd;
3674}
3675
3676/**
3677 * for_each_flag_domain - Iterates over sched_domains containing the flag.
3678 * @cpu: The cpu whose domains we're iterating over.
3679 * @sd: variable holding the value of the power_savings_sd
3680 * for cpu.
3681 * @flag: The flag to filter the sched_domains to be iterated.
3682 *
3683 * Iterates over all the scheduler domains for a given cpu that has the 'flag'
3684 * set, starting from the lowest sched_domain to the highest.
3685 */
3686#define for_each_flag_domain(cpu, sd, flag) \
3687 for (sd = lowest_flag_domain(cpu, flag); \
3688 (sd && (sd->flags & flag)); sd = sd->parent)
3689
3690/**
3691 * is_semi_idle_group - Checks if the given sched_group is semi-idle.
3692 * @ilb_group: group to be checked for semi-idleness
3693 *
3694 * Returns: 1 if the group is semi-idle. 0 otherwise.
3695 *
3696 * We define a sched_group to be semi idle if it has atleast one idle-CPU
3697 * and atleast one non-idle CPU. This helper function checks if the given
3698 * sched_group is semi-idle or not.
3699 */
3700static inline int is_semi_idle_group(struct sched_group *ilb_group)
3701{
3702 cpumask_and(nohz.grp_idle_mask, nohz.idle_cpus_mask,
3703 sched_group_cpus(ilb_group));
3704
3705 /*
3706 * A sched_group is semi-idle when it has atleast one busy cpu
3707 * and atleast one idle cpu.
3708 */
3709 if (cpumask_empty(nohz.grp_idle_mask))
3710 return 0;
3711
3712 if (cpumask_equal(nohz.grp_idle_mask, sched_group_cpus(ilb_group)))
3713 return 0;
3714
3715 return 1;
3716}
3717/**
3718 * find_new_ilb - Finds the optimum idle load balancer for nomination.
3719 * @cpu: The cpu which is nominating a new idle_load_balancer.
3720 *
3721 * Returns: Returns the id of the idle load balancer if it exists,
3722 * Else, returns >= nr_cpu_ids.
3723 *
3724 * This algorithm picks the idle load balancer such that it belongs to a
3725 * semi-idle powersavings sched_domain. The idea is to try and avoid
3726 * completely idle packages/cores just for the purpose of idle load balancing
3727 * when there are other idle cpu's which are better suited for that job.
3728 */
3729static int find_new_ilb(int cpu)
3730{
3731 struct sched_domain *sd;
3732 struct sched_group *ilb_group;
3733 int ilb = nr_cpu_ids;
3734
3735 /*
3736 * Have idle load balancer selection from semi-idle packages only
3737 * when power-aware load balancing is enabled
3738 */
3739 if (!(sched_smt_power_savings || sched_mc_power_savings))
3740 goto out_done;
3741
3742 /*
3743 * Optimize for the case when we have no idle CPUs or only one
3744 * idle CPU. Don't walk the sched_domain hierarchy in such cases
3745 */
3746 if (cpumask_weight(nohz.idle_cpus_mask) < 2)
3747 goto out_done;
3748
3749 rcu_read_lock();
3750 for_each_flag_domain(cpu, sd, SD_POWERSAVINGS_BALANCE) {
3751 ilb_group = sd->groups;
3752
3753 do {
3754 if (is_semi_idle_group(ilb_group)) {
3755 ilb = cpumask_first(nohz.grp_idle_mask);
3756 goto unlock;
3757 }
3758
3759 ilb_group = ilb_group->next;
3760
3761 } while (ilb_group != sd->groups);
3762 }
3763unlock:
3764 rcu_read_unlock();
3765
3766out_done:
3767 return ilb;
3768}
3769#else /* (CONFIG_SCHED_MC || CONFIG_SCHED_SMT) */
3770static inline int find_new_ilb(int call_cpu)
3771{
3772 return nr_cpu_ids;
3773}
3774#endif
3775
3776/*
3777 * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
3778 * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
3779 * CPU (if there is one).
3780 */
3781static void nohz_balancer_kick(int cpu)
3782{
3783 int ilb_cpu;
3784
3785 nohz.next_balance++;
3786
3787 ilb_cpu = get_nohz_load_balancer();
3788
3789 if (ilb_cpu >= nr_cpu_ids) {
3790 ilb_cpu = cpumask_first(nohz.idle_cpus_mask);
3791 if (ilb_cpu >= nr_cpu_ids)
3792 return;
3793 }
3794
3795 if (!cpu_rq(ilb_cpu)->nohz_balance_kick) {
3796 struct call_single_data *cp;
3797
3798 cpu_rq(ilb_cpu)->nohz_balance_kick = 1;
3799 cp = &per_cpu(remote_sched_softirq_cb, cpu);
3800 __smp_call_function_single(ilb_cpu, cp, 0);
3801 }
3802 return;
3803}
3804
3805/*
3806 * This routine will try to nominate the ilb (idle load balancing)
3807 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
3808 * load balancing on behalf of all those cpus.
3809 *
3810 * When the ilb owner becomes busy, we will not have new ilb owner until some
3811 * idle CPU wakes up and goes back to idle or some busy CPU tries to kick
3812 * idle load balancing by kicking one of the idle CPUs.
3813 *
3814 * Ticks are stopped for the ilb owner as well, with busy CPU kicking this
3815 * ilb owner CPU in future (when there is a need for idle load balancing on
3816 * behalf of all idle CPUs).
3817 */
3818void select_nohz_load_balancer(int stop_tick)
3819{
3820 int cpu = smp_processor_id();
3821
3822 if (stop_tick) {
3823 if (!cpu_active(cpu)) {
3824 if (atomic_read(&nohz.load_balancer) != cpu)
3825 return;
3826
3827 /*
3828 * If we are going offline and still the leader,
3829 * give up!
3830 */
3831 if (atomic_cmpxchg(&nohz.load_balancer, cpu,
3832 nr_cpu_ids) != cpu)
3833 BUG();
3834
3835 return;
3836 }
3837
3838 cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
3839
3840 if (atomic_read(&nohz.first_pick_cpu) == cpu)
3841 atomic_cmpxchg(&nohz.first_pick_cpu, cpu, nr_cpu_ids);
3842 if (atomic_read(&nohz.second_pick_cpu) == cpu)
3843 atomic_cmpxchg(&nohz.second_pick_cpu, cpu, nr_cpu_ids);
3844
3845 if (atomic_read(&nohz.load_balancer) >= nr_cpu_ids) {
3846 int new_ilb;
3847
3848 /* make me the ilb owner */
3849 if (atomic_cmpxchg(&nohz.load_balancer, nr_cpu_ids,
3850 cpu) != nr_cpu_ids)
3851 return;
3852
3853 /*
3854 * Check to see if there is a more power-efficient
3855 * ilb.
3856 */
3857 new_ilb = find_new_ilb(cpu);
3858 if (new_ilb < nr_cpu_ids && new_ilb != cpu) {
3859 atomic_set(&nohz.load_balancer, nr_cpu_ids);
3860 resched_cpu(new_ilb);
3861 return;
3862 }
3863 return;
3864 }
3865 } else {
3866 if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
3867 return;
3868
3869 cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
3870
3871 if (atomic_read(&nohz.load_balancer) == cpu)
3872 if (atomic_cmpxchg(&nohz.load_balancer, cpu,
3873 nr_cpu_ids) != cpu)
3874 BUG();
3875 }
3876 return;
3877}
3878#endif
3879
3880static DEFINE_SPINLOCK(balancing);
3881
3882static unsigned long __read_mostly max_load_balance_interval = HZ/10;
3883
3884/*
3885 * Scale the max load_balance interval with the number of CPUs in the system.
3886 * This trades load-balance latency on larger machines for less cross talk.
3887 */
3888static void update_max_interval(void)
3889{
3890 max_load_balance_interval = HZ*num_online_cpus()/10;
3891}
3892
3893/*
3894 * It checks each scheduling domain to see if it is due to be balanced,
3895 * and initiates a balancing operation if so.
3896 *
3897 * Balancing parameters are set up in arch_init_sched_domains.
3898 */
3899static void rebalance_domains(int cpu, enum cpu_idle_type idle)
3900{
3901 int balance = 1;
3902 struct rq *rq = cpu_rq(cpu);
3903 unsigned long interval;
3904 struct sched_domain *sd;
3905 /* Earliest time when we have to do rebalance again */
3906 unsigned long next_balance = jiffies + 60*HZ;
3907 int update_next_balance = 0;
3908 int need_serialize;
3909
3910 update_shares(cpu);
3911
3912 rcu_read_lock();
3913 for_each_domain(cpu, sd) {
3914 if (!(sd->flags & SD_LOAD_BALANCE))
3915 continue;
3916
3917 interval = sd->balance_interval;
3918 if (idle != CPU_IDLE)
3919 interval *= sd->busy_factor;
3920
3921 /* scale ms to jiffies */
3922 interval = msecs_to_jiffies(interval);
3923 interval = clamp(interval, 1UL, max_load_balance_interval);
3924
3925 need_serialize = sd->flags & SD_SERIALIZE;
3926
3927 if (need_serialize) {
3928 if (!spin_trylock(&balancing))
3929 goto out;
3930 }
3931
3932 if (time_after_eq(jiffies, sd->last_balance + interval)) {
3933 if (load_balance(cpu, rq, sd, idle, &balance)) {
3934 /*
3935 * We've pulled tasks over so either we're no
3936 * longer idle.
3937 */
3938 idle = CPU_NOT_IDLE;
3939 }
3940 sd->last_balance = jiffies;
3941 }
3942 if (need_serialize)
3943 spin_unlock(&balancing);
3944out:
3945 if (time_after(next_balance, sd->last_balance + interval)) {
3946 next_balance = sd->last_balance + interval;
3947 update_next_balance = 1;
3948 }
3949
3950 /*
3951 * Stop the load balance at this level. There is another
3952 * CPU in our sched group which is doing load balancing more
3953 * actively.
3954 */
3955 if (!balance)
3956 break;
3957 }
3958 rcu_read_unlock();
3959
3960 /*
3961 * next_balance will be updated only when there is a need.
3962 * When the cpu is attached to null domain for ex, it will not be
3963 * updated.
3964 */
3965 if (likely(update_next_balance))
3966 rq->next_balance = next_balance;
3967}
3968
3969#ifdef CONFIG_NO_HZ
3970/*
3971 * In CONFIG_NO_HZ case, the idle balance kickee will do the
3972 * rebalancing for all the cpus for whom scheduler ticks are stopped.
3973 */
3974static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle)
3975{
3976 struct rq *this_rq = cpu_rq(this_cpu);
3977 struct rq *rq;
3978 int balance_cpu;
3979
3980 if (idle != CPU_IDLE || !this_rq->nohz_balance_kick)
3981 return;
3982
3983 for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
3984 if (balance_cpu == this_cpu)
3985 continue;
3986
3987 /*
3988 * If this cpu gets work to do, stop the load balancing
3989 * work being done for other cpus. Next load
3990 * balancing owner will pick it up.
3991 */
3992 if (need_resched()) {
3993 this_rq->nohz_balance_kick = 0;
3994 break;
3995 }
3996
3997 raw_spin_lock_irq(&this_rq->lock);
3998 update_rq_clock(this_rq);
3999 update_cpu_load(this_rq);
4000 raw_spin_unlock_irq(&this_rq->lock);
4001
4002 rebalance_domains(balance_cpu, CPU_IDLE);
4003
4004 rq = cpu_rq(balance_cpu);
4005 if (time_after(this_rq->next_balance, rq->next_balance))
4006 this_rq->next_balance = rq->next_balance;
4007 }
4008 nohz.next_balance = this_rq->next_balance;
4009 this_rq->nohz_balance_kick = 0;
4010}
4011
4012/*
4013 * Current heuristic for kicking the idle load balancer
4014 * - first_pick_cpu is the one of the busy CPUs. It will kick
4015 * idle load balancer when it has more than one process active. This
4016 * eliminates the need for idle load balancing altogether when we have
4017 * only one running process in the system (common case).
4018 * - If there are more than one busy CPU, idle load balancer may have
4019 * to run for active_load_balance to happen (i.e., two busy CPUs are
4020 * SMT or core siblings and can run better if they move to different
4021 * physical CPUs). So, second_pick_cpu is the second of the busy CPUs
4022 * which will kick idle load balancer as soon as it has any load.
4023 */
4024static inline int nohz_kick_needed(struct rq *rq, int cpu)
4025{
4026 unsigned long now = jiffies;
4027 int ret;
4028 int first_pick_cpu, second_pick_cpu;
4029
4030 if (time_before(now, nohz.next_balance))
4031 return 0;
4032
4033 if (rq->idle_at_tick)
4034 return 0;
4035
4036 first_pick_cpu = atomic_read(&nohz.first_pick_cpu);
4037 second_pick_cpu = atomic_read(&nohz.second_pick_cpu);
4038
4039 if (first_pick_cpu < nr_cpu_ids && first_pick_cpu != cpu &&
4040 second_pick_cpu < nr_cpu_ids && second_pick_cpu != cpu)
4041 return 0;
4042
4043 ret = atomic_cmpxchg(&nohz.first_pick_cpu, nr_cpu_ids, cpu);
4044 if (ret == nr_cpu_ids || ret == cpu) {
4045 atomic_cmpxchg(&nohz.second_pick_cpu, cpu, nr_cpu_ids);
4046 if (rq->nr_running > 1)
4047 return 1;
4048 } else {
4049 ret = atomic_cmpxchg(&nohz.second_pick_cpu, nr_cpu_ids, cpu);
4050 if (ret == nr_cpu_ids || ret == cpu) {
4051 if (rq->nr_running)
4052 return 1;
4053 }
4054 }
4055 return 0;
4056}
4057#else
4058static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { }
4059#endif
4060
4061/*
4062 * run_rebalance_domains is triggered when needed from the scheduler tick.
4063 * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
4064 */
4065static void run_rebalance_domains(struct softirq_action *h)
4066{
4067 int this_cpu = smp_processor_id();
4068 struct rq *this_rq = cpu_rq(this_cpu);
4069 enum cpu_idle_type idle = this_rq->idle_at_tick ?
4070 CPU_IDLE : CPU_NOT_IDLE;
4071
4072 rebalance_domains(this_cpu, idle);
4073
4074 /*
4075 * If this cpu has a pending nohz_balance_kick, then do the
4076 * balancing on behalf of the other idle cpus whose ticks are
4077 * stopped.
4078 */
4079 nohz_idle_balance(this_cpu, idle);
4080}
4081
4082static inline int on_null_domain(int cpu)
4083{
4084 return !rcu_dereference_sched(cpu_rq(cpu)->sd);
4085}
4086
4087/*
4088 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
4089 */
4090static inline void trigger_load_balance(struct rq *rq, int cpu)
4091{
4092 /* Don't need to rebalance while attached to NULL domain */
4093 if (time_after_eq(jiffies, rq->next_balance) &&
4094 likely(!on_null_domain(cpu)))
4095 raise_softirq(SCHED_SOFTIRQ);
4096#ifdef CONFIG_NO_HZ
4097 else if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu)))
4098 nohz_balancer_kick(cpu);
4099#endif
4100}
4101
4102static void rq_online_fair(struct rq *rq)
4103{
4104 update_sysctl();
4105}
4106
4107static void rq_offline_fair(struct rq *rq)
4108{
4109 update_sysctl();
4110}
4111
4112#else /* CONFIG_SMP */
4113
4114/*
4115 * on UP we do not need to balance between CPUs:
4116 */
4117static inline void idle_balance(int cpu, struct rq *rq)
4118{
4119}
4120
4121#endif /* CONFIG_SMP */
4122
4123/*
4124 * scheduler tick hitting a task of our scheduling class:
4125 */
4126static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
4127{
4128 struct cfs_rq *cfs_rq;
4129 struct sched_entity *se = &curr->se;
4130
4131 for_each_sched_entity(se) {
4132 cfs_rq = cfs_rq_of(se);
4133 entity_tick(cfs_rq, se, queued);
4134 }
4135}
4136
4137/*
4138 * called on fork with the child task as argument from the parent's context
4139 * - child not yet on the tasklist
4140 * - preemption disabled
4141 */
4142static void task_fork_fair(struct task_struct *p)
4143{
4144 struct cfs_rq *cfs_rq = task_cfs_rq(current);
4145 struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
4146 int this_cpu = smp_processor_id();
4147 struct rq *rq = this_rq();
4148 unsigned long flags;
4149
4150 raw_spin_lock_irqsave(&rq->lock, flags);
4151
4152 update_rq_clock(rq);
4153
4154 if (unlikely(task_cpu(p) != this_cpu)) {
4155 rcu_read_lock();
4156 __set_task_cpu(p, this_cpu);
4157 rcu_read_unlock();
4158 }
4159
4160 update_curr(cfs_rq);
4161
4162 if (curr)
4163 se->vruntime = curr->vruntime;
4164 place_entity(cfs_rq, se, 1);
4165
4166 if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
4167 /*
4168 * Upon rescheduling, sched_class::put_prev_task() will place
4169 * 'current' within the tree based on its new key value.
4170 */
4171 swap(curr->vruntime, se->vruntime);
4172 resched_task(rq->curr);
4173 }
4174
4175 se->vruntime -= cfs_rq->min_vruntime;
4176
4177 raw_spin_unlock_irqrestore(&rq->lock, flags);
4178}
4179
4180/*
4181 * Priority of the task has changed. Check to see if we preempt
4182 * the current task.
4183 */
4184static void
4185prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
4186{
4187 if (!p->se.on_rq)
4188 return;
4189
4190 /*
4191 * Reschedule if we are currently running on this runqueue and
4192 * our priority decreased, or if we are not currently running on
4193 * this runqueue and our priority is higher than the current's
4194 */
4195 if (rq->curr == p) {
4196 if (p->prio > oldprio)
4197 resched_task(rq->curr);
4198 } else
4199 check_preempt_curr(rq, p, 0);
4200}
4201
4202static void switched_from_fair(struct rq *rq, struct task_struct *p)
4203{
4204 struct sched_entity *se = &p->se;
4205 struct cfs_rq *cfs_rq = cfs_rq_of(se);
4206
4207 /*
4208 * Ensure the task's vruntime is normalized, so that when its
4209 * switched back to the fair class the enqueue_entity(.flags=0) will
4210 * do the right thing.
4211 *
4212 * If it was on_rq, then the dequeue_entity(.flags=0) will already
4213 * have normalized the vruntime, if it was !on_rq, then only when
4214 * the task is sleeping will it still have non-normalized vruntime.
4215 */
4216 if (!se->on_rq && p->state != TASK_RUNNING) {
4217 /*
4218 * Fix up our vruntime so that the current sleep doesn't
4219 * cause 'unlimited' sleep bonus.
4220 */
4221 place_entity(cfs_rq, se, 0);
4222 se->vruntime -= cfs_rq->min_vruntime;
4223 }
4224}
4225
4226/*
4227 * We switched to the sched_fair class.
4228 */
4229static void switched_to_fair(struct rq *rq, struct task_struct *p)
4230{
4231 if (!p->se.on_rq)
4232 return;
4233
4234 /*
4235 * We were most likely switched from sched_rt, so
4236 * kick off the schedule if running, otherwise just see
4237 * if we can still preempt the current task.
4238 */
4239 if (rq->curr == p)
4240 resched_task(rq->curr);
4241 else
4242 check_preempt_curr(rq, p, 0);
4243}
4244
4245/* Account for a task changing its policy or group.
4246 *
4247 * This routine is mostly called to set cfs_rq->curr field when a task
4248 * migrates between groups/classes.
4249 */
4250static void set_curr_task_fair(struct rq *rq)
4251{
4252 struct sched_entity *se = &rq->curr->se;
4253
4254 for_each_sched_entity(se)
4255 set_next_entity(cfs_rq_of(se), se);
4256}
4257
4258#ifdef CONFIG_FAIR_GROUP_SCHED
4259static void task_move_group_fair(struct task_struct *p, int on_rq)
4260{
4261 /*
4262 * If the task was not on the rq at the time of this cgroup movement
4263 * it must have been asleep, sleeping tasks keep their ->vruntime
4264 * absolute on their old rq until wakeup (needed for the fair sleeper
4265 * bonus in place_entity()).
4266 *
4267 * If it was on the rq, we've just 'preempted' it, which does convert
4268 * ->vruntime to a relative base.
4269 *
4270 * Make sure both cases convert their relative position when migrating
4271 * to another cgroup's rq. This does somewhat interfere with the
4272 * fair sleeper stuff for the first placement, but who cares.
4273 */
4274 if (!on_rq)
4275 p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime;
4276 set_task_rq(p, task_cpu(p));
4277 if (!on_rq)
4278 p->se.vruntime += cfs_rq_of(&p->se)->min_vruntime;
4279}
4280#endif
4281
4282static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
4283{
4284 struct sched_entity *se = &task->se;
4285 unsigned int rr_interval = 0;
4286
4287 /*
4288 * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
4289 * idle runqueue:
4290 */
4291 if (rq->cfs.load.weight)
4292 rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
4293
4294 return rr_interval;
4295}
4296
4297/*
4298 * All the scheduling class methods:
4299 */
4300static const struct sched_class fair_sched_class = {
4301 .next = &idle_sched_class,
4302 .enqueue_task = enqueue_task_fair,
4303 .dequeue_task = dequeue_task_fair,
4304 .yield_task = yield_task_fair,
4305 .yield_to_task = yield_to_task_fair,
4306
4307 .check_preempt_curr = check_preempt_wakeup,
4308
4309 .pick_next_task = pick_next_task_fair,
4310 .put_prev_task = put_prev_task_fair,
4311
4312#ifdef CONFIG_SMP
4313 .select_task_rq = select_task_rq_fair,
4314
4315 .rq_online = rq_online_fair,
4316 .rq_offline = rq_offline_fair,
4317
4318 .task_waking = task_waking_fair,
4319#endif
4320
4321 .set_curr_task = set_curr_task_fair,
4322 .task_tick = task_tick_fair,
4323 .task_fork = task_fork_fair,
4324
4325 .prio_changed = prio_changed_fair,
4326 .switched_from = switched_from_fair,
4327 .switched_to = switched_to_fair,
4328
4329 .get_rr_interval = get_rr_interval_fair,
4330
4331#ifdef CONFIG_FAIR_GROUP_SCHED
4332 .task_move_group = task_move_group_fair,
4333#endif
4334};
4335
4336#ifdef CONFIG_SCHED_DEBUG
4337static void print_cfs_stats(struct seq_file *m, int cpu)
4338{
4339 struct cfs_rq *cfs_rq;
4340
4341 rcu_read_lock();
4342 for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
4343 print_cfs_rq(m, cpu, cfs_rq);
4344 rcu_read_unlock();
4345}
4346#endif