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Merge branch 'linus' into perfcounters/core
[linux-2.6.git] / kernel / sched_fair.c
1 /*
2  * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH)
3  *
4  *  Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
5  *
6  *  Interactivity improvements by Mike Galbraith
7  *  (C) 2007 Mike Galbraith <efault@gmx.de>
8  *
9  *  Various enhancements by Dmitry Adamushko.
10  *  (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com>
11  *
12  *  Group scheduling enhancements by Srivatsa Vaddagiri
13  *  Copyright IBM Corporation, 2007
14  *  Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
15  *
16  *  Scaled math optimizations by Thomas Gleixner
17  *  Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de>
18  *
19  *  Adaptive scheduling granularity, math enhancements by Peter Zijlstra
20  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
21  */
22
23 #include <linux/latencytop.h>
24
25 /*
26  * Targeted preemption latency for CPU-bound tasks:
27  * (default: 5ms * (1 + ilog(ncpus)), units: nanoseconds)
28  *
29  * NOTE: this latency value is not the same as the concept of
30  * 'timeslice length' - timeslices in CFS are of variable length
31  * and have no persistent notion like in traditional, time-slice
32  * based scheduling concepts.
33  *
34  * (to see the precise effective timeslice length of your workload,
35  *  run vmstat and monitor the context-switches (cs) field)
36  */
37 unsigned int sysctl_sched_latency = 5000000ULL;
38
39 /*
40  * Minimal preemption granularity for CPU-bound tasks:
41  * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
42  */
43 unsigned int sysctl_sched_min_granularity = 1000000ULL;
44
45 /*
46  * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
47  */
48 static unsigned int sched_nr_latency = 5;
49
50 /*
51  * After fork, child runs first. If set to 0 (default) then
52  * parent will (try to) run first.
53  */
54 unsigned int sysctl_sched_child_runs_first __read_mostly;
55
56 /*
57  * sys_sched_yield() compat mode
58  *
59  * This option switches the agressive yield implementation of the
60  * old scheduler back on.
61  */
62 unsigned int __read_mostly sysctl_sched_compat_yield;
63
64 /*
65  * SCHED_OTHER wake-up granularity.
66  * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
67  *
68  * This option delays the preemption effects of decoupled workloads
69  * and reduces their over-scheduling. Synchronous workloads will still
70  * have immediate wakeup/sleep latencies.
71  */
72 unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
73
74 const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
75
76 static const struct sched_class fair_sched_class;
77
78 /**************************************************************
79  * CFS operations on generic schedulable entities:
80  */
81
82 #ifdef CONFIG_FAIR_GROUP_SCHED
83
84 /* cpu runqueue to which this cfs_rq is attached */
85 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
86 {
87         return cfs_rq->rq;
88 }
89
90 /* An entity is a task if it doesn't "own" a runqueue */
91 #define entity_is_task(se)      (!se->my_q)
92
93 static inline struct task_struct *task_of(struct sched_entity *se)
94 {
95 #ifdef CONFIG_SCHED_DEBUG
96         WARN_ON_ONCE(!entity_is_task(se));
97 #endif
98         return container_of(se, struct task_struct, se);
99 }
100
101 /* Walk up scheduling entities hierarchy */
102 #define for_each_sched_entity(se) \
103                 for (; se; se = se->parent)
104
105 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
106 {
107         return p->se.cfs_rq;
108 }
109
110 /* runqueue on which this entity is (to be) queued */
111 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
112 {
113         return se->cfs_rq;
114 }
115
116 /* runqueue "owned" by this group */
117 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
118 {
119         return grp->my_q;
120 }
121
122 /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on
123  * another cpu ('this_cpu')
124  */
125 static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
126 {
127         return cfs_rq->tg->cfs_rq[this_cpu];
128 }
129
130 /* Iterate thr' all leaf cfs_rq's on a runqueue */
131 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
132         list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
133
134 /* Do the two (enqueued) entities belong to the same group ? */
135 static inline int
136 is_same_group(struct sched_entity *se, struct sched_entity *pse)
137 {
138         if (se->cfs_rq == pse->cfs_rq)
139                 return 1;
140
141         return 0;
142 }
143
144 static inline struct sched_entity *parent_entity(struct sched_entity *se)
145 {
146         return se->parent;
147 }
148
149 /* return depth at which a sched entity is present in the hierarchy */
150 static inline int depth_se(struct sched_entity *se)
151 {
152         int depth = 0;
153
154         for_each_sched_entity(se)
155                 depth++;
156
157         return depth;
158 }
159
160 static void
161 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
162 {
163         int se_depth, pse_depth;
164
165         /*
166          * preemption test can be made between sibling entities who are in the
167          * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
168          * both tasks until we find their ancestors who are siblings of common
169          * parent.
170          */
171
172         /* First walk up until both entities are at same depth */
173         se_depth = depth_se(*se);
174         pse_depth = depth_se(*pse);
175
176         while (se_depth > pse_depth) {
177                 se_depth--;
178                 *se = parent_entity(*se);
179         }
180
181         while (pse_depth > se_depth) {
182                 pse_depth--;
183                 *pse = parent_entity(*pse);
184         }
185
186         while (!is_same_group(*se, *pse)) {
187                 *se = parent_entity(*se);
188                 *pse = parent_entity(*pse);
189         }
190 }
191
192 #else   /* !CONFIG_FAIR_GROUP_SCHED */
193
194 static inline struct task_struct *task_of(struct sched_entity *se)
195 {
196         return container_of(se, struct task_struct, se);
197 }
198
199 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
200 {
201         return container_of(cfs_rq, struct rq, cfs);
202 }
203
204 #define entity_is_task(se)      1
205
206 #define for_each_sched_entity(se) \
207                 for (; se; se = NULL)
208
209 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
210 {
211         return &task_rq(p)->cfs;
212 }
213
214 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
215 {
216         struct task_struct *p = task_of(se);
217         struct rq *rq = task_rq(p);
218
219         return &rq->cfs;
220 }
221
222 /* runqueue "owned" by this group */
223 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
224 {
225         return NULL;
226 }
227
228 static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
229 {
230         return &cpu_rq(this_cpu)->cfs;
231 }
232
233 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
234                 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
235
236 static inline int
237 is_same_group(struct sched_entity *se, struct sched_entity *pse)
238 {
239         return 1;
240 }
241
242 static inline struct sched_entity *parent_entity(struct sched_entity *se)
243 {
244         return NULL;
245 }
246
247 static inline void
248 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
249 {
250 }
251
252 #endif  /* CONFIG_FAIR_GROUP_SCHED */
253
254
255 /**************************************************************
256  * Scheduling class tree data structure manipulation methods:
257  */
258
259 static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime)
260 {
261         s64 delta = (s64)(vruntime - min_vruntime);
262         if (delta > 0)
263                 min_vruntime = vruntime;
264
265         return min_vruntime;
266 }
267
268 static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
269 {
270         s64 delta = (s64)(vruntime - min_vruntime);
271         if (delta < 0)
272                 min_vruntime = vruntime;
273
274         return min_vruntime;
275 }
276
277 static inline int entity_before(struct sched_entity *a,
278                                 struct sched_entity *b)
279 {
280         return (s64)(a->vruntime - b->vruntime) < 0;
281 }
282
283 static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
284 {
285         return se->vruntime - cfs_rq->min_vruntime;
286 }
287
288 static void update_min_vruntime(struct cfs_rq *cfs_rq)
289 {
290         u64 vruntime = cfs_rq->min_vruntime;
291
292         if (cfs_rq->curr)
293                 vruntime = cfs_rq->curr->vruntime;
294
295         if (cfs_rq->rb_leftmost) {
296                 struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost,
297                                                    struct sched_entity,
298                                                    run_node);
299
300                 if (!cfs_rq->curr)
301                         vruntime = se->vruntime;
302                 else
303                         vruntime = min_vruntime(vruntime, se->vruntime);
304         }
305
306         cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
307 }
308
309 /*
310  * Enqueue an entity into the rb-tree:
311  */
312 static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
313 {
314         struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
315         struct rb_node *parent = NULL;
316         struct sched_entity *entry;
317         s64 key = entity_key(cfs_rq, se);
318         int leftmost = 1;
319
320         /*
321          * Find the right place in the rbtree:
322          */
323         while (*link) {
324                 parent = *link;
325                 entry = rb_entry(parent, struct sched_entity, run_node);
326                 /*
327                  * We dont care about collisions. Nodes with
328                  * the same key stay together.
329                  */
330                 if (key < entity_key(cfs_rq, entry)) {
331                         link = &parent->rb_left;
332                 } else {
333                         link = &parent->rb_right;
334                         leftmost = 0;
335                 }
336         }
337
338         /*
339          * Maintain a cache of leftmost tree entries (it is frequently
340          * used):
341          */
342         if (leftmost)
343                 cfs_rq->rb_leftmost = &se->run_node;
344
345         rb_link_node(&se->run_node, parent, link);
346         rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
347 }
348
349 static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
350 {
351         if (cfs_rq->rb_leftmost == &se->run_node) {
352                 struct rb_node *next_node;
353
354                 next_node = rb_next(&se->run_node);
355                 cfs_rq->rb_leftmost = next_node;
356         }
357
358         rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
359 }
360
361 static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
362 {
363         struct rb_node *left = cfs_rq->rb_leftmost;
364
365         if (!left)
366                 return NULL;
367
368         return rb_entry(left, struct sched_entity, run_node);
369 }
370
371 static struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
372 {
373         struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
374
375         if (!last)
376                 return NULL;
377
378         return rb_entry(last, struct sched_entity, run_node);
379 }
380
381 /**************************************************************
382  * Scheduling class statistics methods:
383  */
384
385 #ifdef CONFIG_SCHED_DEBUG
386 int sched_nr_latency_handler(struct ctl_table *table, int write,
387                 struct file *filp, void __user *buffer, size_t *lenp,
388                 loff_t *ppos)
389 {
390         int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
391
392         if (ret || !write)
393                 return ret;
394
395         sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
396                                         sysctl_sched_min_granularity);
397
398         return 0;
399 }
400 #endif
401
402 /*
403  * delta /= w
404  */
405 static inline unsigned long
406 calc_delta_fair(unsigned long delta, struct sched_entity *se)
407 {
408         if (unlikely(se->load.weight != NICE_0_LOAD))
409                 delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load);
410
411         return delta;
412 }
413
414 /*
415  * The idea is to set a period in which each task runs once.
416  *
417  * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
418  * this period because otherwise the slices get too small.
419  *
420  * p = (nr <= nl) ? l : l*nr/nl
421  */
422 static u64 __sched_period(unsigned long nr_running)
423 {
424         u64 period = sysctl_sched_latency;
425         unsigned long nr_latency = sched_nr_latency;
426
427         if (unlikely(nr_running > nr_latency)) {
428                 period = sysctl_sched_min_granularity;
429                 period *= nr_running;
430         }
431
432         return period;
433 }
434
435 /*
436  * We calculate the wall-time slice from the period by taking a part
437  * proportional to the weight.
438  *
439  * s = p*P[w/rw]
440  */
441 static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
442 {
443         u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq);
444
445         for_each_sched_entity(se) {
446                 struct load_weight *load;
447                 struct load_weight lw;
448
449                 cfs_rq = cfs_rq_of(se);
450                 load = &cfs_rq->load;
451
452                 if (unlikely(!se->on_rq)) {
453                         lw = cfs_rq->load;
454
455                         update_load_add(&lw, se->load.weight);
456                         load = &lw;
457                 }
458                 slice = calc_delta_mine(slice, se->load.weight, load);
459         }
460         return slice;
461 }
462
463 /*
464  * We calculate the vruntime slice of a to be inserted task
465  *
466  * vs = s/w
467  */
468 static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
469 {
470         return calc_delta_fair(sched_slice(cfs_rq, se), se);
471 }
472
473 /*
474  * Update the current task's runtime statistics. Skip current tasks that
475  * are not in our scheduling class.
476  */
477 static inline void
478 __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
479               unsigned long delta_exec)
480 {
481         unsigned long delta_exec_weighted;
482
483         schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
484
485         curr->sum_exec_runtime += delta_exec;
486         schedstat_add(cfs_rq, exec_clock, delta_exec);
487         delta_exec_weighted = calc_delta_fair(delta_exec, curr);
488         curr->vruntime += delta_exec_weighted;
489         update_min_vruntime(cfs_rq);
490 }
491
492 static void update_curr(struct cfs_rq *cfs_rq)
493 {
494         struct sched_entity *curr = cfs_rq->curr;
495         u64 now = rq_of(cfs_rq)->clock;
496         unsigned long delta_exec;
497
498         if (unlikely(!curr))
499                 return;
500
501         /*
502          * Get the amount of time the current task was running
503          * since the last time we changed load (this cannot
504          * overflow on 32 bits):
505          */
506         delta_exec = (unsigned long)(now - curr->exec_start);
507         if (!delta_exec)
508                 return;
509
510         __update_curr(cfs_rq, curr, delta_exec);
511         curr->exec_start = now;
512
513         if (entity_is_task(curr)) {
514                 struct task_struct *curtask = task_of(curr);
515
516                 trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
517                 cpuacct_charge(curtask, delta_exec);
518                 account_group_exec_runtime(curtask, delta_exec);
519         }
520 }
521
522 static inline void
523 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
524 {
525         schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
526 }
527
528 /*
529  * Task is being enqueued - update stats:
530  */
531 static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
532 {
533         /*
534          * Are we enqueueing a waiting task? (for current tasks
535          * a dequeue/enqueue event is a NOP)
536          */
537         if (se != cfs_rq->curr)
538                 update_stats_wait_start(cfs_rq, se);
539 }
540
541 static void
542 update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
543 {
544         schedstat_set(se->wait_max, max(se->wait_max,
545                         rq_of(cfs_rq)->clock - se->wait_start));
546         schedstat_set(se->wait_count, se->wait_count + 1);
547         schedstat_set(se->wait_sum, se->wait_sum +
548                         rq_of(cfs_rq)->clock - se->wait_start);
549 #ifdef CONFIG_SCHEDSTATS
550         if (entity_is_task(se)) {
551                 trace_sched_stat_wait(task_of(se),
552                         rq_of(cfs_rq)->clock - se->wait_start);
553         }
554 #endif
555         schedstat_set(se->wait_start, 0);
556 }
557
558 static inline void
559 update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
560 {
561         /*
562          * Mark the end of the wait period if dequeueing a
563          * waiting task:
564          */
565         if (se != cfs_rq->curr)
566                 update_stats_wait_end(cfs_rq, se);
567 }
568
569 /*
570  * We are picking a new current task - update its stats:
571  */
572 static inline void
573 update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
574 {
575         /*
576          * We are starting a new run period:
577          */
578         se->exec_start = rq_of(cfs_rq)->clock;
579 }
580
581 /**************************************************
582  * Scheduling class queueing methods:
583  */
584
585 #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
586 static void
587 add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
588 {
589         cfs_rq->task_weight += weight;
590 }
591 #else
592 static inline void
593 add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
594 {
595 }
596 #endif
597
598 static void
599 account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
600 {
601         update_load_add(&cfs_rq->load, se->load.weight);
602         if (!parent_entity(se))
603                 inc_cpu_load(rq_of(cfs_rq), se->load.weight);
604         if (entity_is_task(se)) {
605                 add_cfs_task_weight(cfs_rq, se->load.weight);
606                 list_add(&se->group_node, &cfs_rq->tasks);
607         }
608         cfs_rq->nr_running++;
609         se->on_rq = 1;
610 }
611
612 static void
613 account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
614 {
615         update_load_sub(&cfs_rq->load, se->load.weight);
616         if (!parent_entity(se))
617                 dec_cpu_load(rq_of(cfs_rq), se->load.weight);
618         if (entity_is_task(se)) {
619                 add_cfs_task_weight(cfs_rq, -se->load.weight);
620                 list_del_init(&se->group_node);
621         }
622         cfs_rq->nr_running--;
623         se->on_rq = 0;
624 }
625
626 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
627 {
628 #ifdef CONFIG_SCHEDSTATS
629         struct task_struct *tsk = NULL;
630
631         if (entity_is_task(se))
632                 tsk = task_of(se);
633
634         if (se->sleep_start) {
635                 u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
636
637                 if ((s64)delta < 0)
638                         delta = 0;
639
640                 if (unlikely(delta > se->sleep_max))
641                         se->sleep_max = delta;
642
643                 se->sleep_start = 0;
644                 se->sum_sleep_runtime += delta;
645
646                 if (tsk) {
647                         account_scheduler_latency(tsk, delta >> 10, 1);
648                         trace_sched_stat_sleep(tsk, delta);
649                 }
650         }
651         if (se->block_start) {
652                 u64 delta = rq_of(cfs_rq)->clock - se->block_start;
653
654                 if ((s64)delta < 0)
655                         delta = 0;
656
657                 if (unlikely(delta > se->block_max))
658                         se->block_max = delta;
659
660                 se->block_start = 0;
661                 se->sum_sleep_runtime += delta;
662
663                 if (tsk) {
664                         if (tsk->in_iowait) {
665                                 se->iowait_sum += delta;
666                                 se->iowait_count++;
667                                 trace_sched_stat_iowait(tsk, delta);
668                         }
669
670                         /*
671                          * Blocking time is in units of nanosecs, so shift by
672                          * 20 to get a milliseconds-range estimation of the
673                          * amount of time that the task spent sleeping:
674                          */
675                         if (unlikely(prof_on == SLEEP_PROFILING)) {
676                                 profile_hits(SLEEP_PROFILING,
677                                                 (void *)get_wchan(tsk),
678                                                 delta >> 20);
679                         }
680                         account_scheduler_latency(tsk, delta >> 10, 0);
681                 }
682         }
683 #endif
684 }
685
686 static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
687 {
688 #ifdef CONFIG_SCHED_DEBUG
689         s64 d = se->vruntime - cfs_rq->min_vruntime;
690
691         if (d < 0)
692                 d = -d;
693
694         if (d > 3*sysctl_sched_latency)
695                 schedstat_inc(cfs_rq, nr_spread_over);
696 #endif
697 }
698
699 static void
700 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
701 {
702         u64 vruntime = cfs_rq->min_vruntime;
703
704         /*
705          * The 'current' period is already promised to the current tasks,
706          * however the extra weight of the new task will slow them down a
707          * little, place the new task so that it fits in the slot that
708          * stays open at the end.
709          */
710         if (initial && sched_feat(START_DEBIT))
711                 vruntime += sched_vslice(cfs_rq, se);
712
713         if (!initial) {
714                 /* sleeps upto a single latency don't count. */
715                 if (sched_feat(FAIR_SLEEPERS)) {
716                         unsigned long thresh = sysctl_sched_latency;
717
718                         /*
719                          * Convert the sleeper threshold into virtual time.
720                          * SCHED_IDLE is a special sub-class.  We care about
721                          * fairness only relative to other SCHED_IDLE tasks,
722                          * all of which have the same weight.
723                          */
724                         if (sched_feat(NORMALIZED_SLEEPER) &&
725                                         (!entity_is_task(se) ||
726                                          task_of(se)->policy != SCHED_IDLE))
727                                 thresh = calc_delta_fair(thresh, se);
728
729                         /*
730                          * Halve their sleep time's effect, to allow
731                          * for a gentler effect of sleepers:
732                          */
733                         if (sched_feat(GENTLE_FAIR_SLEEPERS))
734                                 thresh >>= 1;
735
736                         vruntime -= thresh;
737                 }
738         }
739
740         /* ensure we never gain time by being placed backwards. */
741         vruntime = max_vruntime(se->vruntime, vruntime);
742
743         se->vruntime = vruntime;
744 }
745
746 static void
747 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
748 {
749         /*
750          * Update run-time statistics of the 'current'.
751          */
752         update_curr(cfs_rq);
753         account_entity_enqueue(cfs_rq, se);
754
755         if (wakeup) {
756                 place_entity(cfs_rq, se, 0);
757                 enqueue_sleeper(cfs_rq, se);
758         }
759
760         update_stats_enqueue(cfs_rq, se);
761         check_spread(cfs_rq, se);
762         if (se != cfs_rq->curr)
763                 __enqueue_entity(cfs_rq, se);
764 }
765
766 static void __clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
767 {
768         if (!se || cfs_rq->last == se)
769                 cfs_rq->last = NULL;
770
771         if (!se || cfs_rq->next == se)
772                 cfs_rq->next = NULL;
773 }
774
775 static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
776 {
777         for_each_sched_entity(se)
778                 __clear_buddies(cfs_rq_of(se), se);
779 }
780
781 static void
782 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
783 {
784         /*
785          * Update run-time statistics of the 'current'.
786          */
787         update_curr(cfs_rq);
788
789         update_stats_dequeue(cfs_rq, se);
790         if (sleep) {
791 #ifdef CONFIG_SCHEDSTATS
792                 if (entity_is_task(se)) {
793                         struct task_struct *tsk = task_of(se);
794
795                         if (tsk->state & TASK_INTERRUPTIBLE)
796                                 se->sleep_start = rq_of(cfs_rq)->clock;
797                         if (tsk->state & TASK_UNINTERRUPTIBLE)
798                                 se->block_start = rq_of(cfs_rq)->clock;
799                 }
800 #endif
801         }
802
803         clear_buddies(cfs_rq, se);
804
805         if (se != cfs_rq->curr)
806                 __dequeue_entity(cfs_rq, se);
807         account_entity_dequeue(cfs_rq, se);
808         update_min_vruntime(cfs_rq);
809 }
810
811 /*
812  * Preempt the current task with a newly woken task if needed:
813  */
814 static void
815 check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
816 {
817         unsigned long ideal_runtime, delta_exec;
818
819         ideal_runtime = sched_slice(cfs_rq, curr);
820         delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
821         if (delta_exec > ideal_runtime) {
822                 resched_task(rq_of(cfs_rq)->curr);
823                 /*
824                  * The current task ran long enough, ensure it doesn't get
825                  * re-elected due to buddy favours.
826                  */
827                 clear_buddies(cfs_rq, curr);
828         }
829 }
830
831 static void
832 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
833 {
834         /* 'current' is not kept within the tree. */
835         if (se->on_rq) {
836                 /*
837                  * Any task has to be enqueued before it get to execute on
838                  * a CPU. So account for the time it spent waiting on the
839                  * runqueue.
840                  */
841                 update_stats_wait_end(cfs_rq, se);
842                 __dequeue_entity(cfs_rq, se);
843         }
844
845         update_stats_curr_start(cfs_rq, se);
846         cfs_rq->curr = se;
847 #ifdef CONFIG_SCHEDSTATS
848         /*
849          * Track our maximum slice length, if the CPU's load is at
850          * least twice that of our own weight (i.e. dont track it
851          * when there are only lesser-weight tasks around):
852          */
853         if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
854                 se->slice_max = max(se->slice_max,
855                         se->sum_exec_runtime - se->prev_sum_exec_runtime);
856         }
857 #endif
858         se->prev_sum_exec_runtime = se->sum_exec_runtime;
859 }
860
861 static int
862 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
863
864 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
865 {
866         struct sched_entity *se = __pick_next_entity(cfs_rq);
867
868         if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, se) < 1)
869                 return cfs_rq->next;
870
871         if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, se) < 1)
872                 return cfs_rq->last;
873
874         return se;
875 }
876
877 static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
878 {
879         /*
880          * If still on the runqueue then deactivate_task()
881          * was not called and update_curr() has to be done:
882          */
883         if (prev->on_rq)
884                 update_curr(cfs_rq);
885
886         check_spread(cfs_rq, prev);
887         if (prev->on_rq) {
888                 update_stats_wait_start(cfs_rq, prev);
889                 /* Put 'current' back into the tree. */
890                 __enqueue_entity(cfs_rq, prev);
891         }
892         cfs_rq->curr = NULL;
893 }
894
895 static void
896 entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
897 {
898         /*
899          * Update run-time statistics of the 'current'.
900          */
901         update_curr(cfs_rq);
902
903 #ifdef CONFIG_SCHED_HRTICK
904         /*
905          * queued ticks are scheduled to match the slice, so don't bother
906          * validating it and just reschedule.
907          */
908         if (queued) {
909                 resched_task(rq_of(cfs_rq)->curr);
910                 return;
911         }
912         /*
913          * don't let the period tick interfere with the hrtick preemption
914          */
915         if (!sched_feat(DOUBLE_TICK) &&
916                         hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
917                 return;
918 #endif
919
920         if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
921                 check_preempt_tick(cfs_rq, curr);
922 }
923
924 /**************************************************
925  * CFS operations on tasks:
926  */
927
928 #ifdef CONFIG_SCHED_HRTICK
929 static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
930 {
931         struct sched_entity *se = &p->se;
932         struct cfs_rq *cfs_rq = cfs_rq_of(se);
933
934         WARN_ON(task_rq(p) != rq);
935
936         if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) {
937                 u64 slice = sched_slice(cfs_rq, se);
938                 u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
939                 s64 delta = slice - ran;
940
941                 if (delta < 0) {
942                         if (rq->curr == p)
943                                 resched_task(p);
944                         return;
945                 }
946
947                 /*
948                  * Don't schedule slices shorter than 10000ns, that just
949                  * doesn't make sense. Rely on vruntime for fairness.
950                  */
951                 if (rq->curr != p)
952                         delta = max_t(s64, 10000LL, delta);
953
954                 hrtick_start(rq, delta);
955         }
956 }
957
958 /*
959  * called from enqueue/dequeue and updates the hrtick when the
960  * current task is from our class and nr_running is low enough
961  * to matter.
962  */
963 static void hrtick_update(struct rq *rq)
964 {
965         struct task_struct *curr = rq->curr;
966
967         if (curr->sched_class != &fair_sched_class)
968                 return;
969
970         if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
971                 hrtick_start_fair(rq, curr);
972 }
973 #else /* !CONFIG_SCHED_HRTICK */
974 static inline void
975 hrtick_start_fair(struct rq *rq, struct task_struct *p)
976 {
977 }
978
979 static inline void hrtick_update(struct rq *rq)
980 {
981 }
982 #endif
983
984 /*
985  * The enqueue_task method is called before nr_running is
986  * increased. Here we update the fair scheduling stats and
987  * then put the task into the rbtree:
988  */
989 static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
990 {
991         struct cfs_rq *cfs_rq;
992         struct sched_entity *se = &p->se;
993
994         for_each_sched_entity(se) {
995                 if (se->on_rq)
996                         break;
997                 cfs_rq = cfs_rq_of(se);
998                 enqueue_entity(cfs_rq, se, wakeup);
999                 wakeup = 1;
1000         }
1001
1002         hrtick_update(rq);
1003 }
1004
1005 /*
1006  * The dequeue_task method is called before nr_running is
1007  * decreased. We remove the task from the rbtree and
1008  * update the fair scheduling stats:
1009  */
1010 static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
1011 {
1012         struct cfs_rq *cfs_rq;
1013         struct sched_entity *se = &p->se;
1014
1015         for_each_sched_entity(se) {
1016                 cfs_rq = cfs_rq_of(se);
1017                 dequeue_entity(cfs_rq, se, sleep);
1018                 /* Don't dequeue parent if it has other entities besides us */
1019                 if (cfs_rq->load.weight)
1020                         break;
1021                 sleep = 1;
1022         }
1023
1024         hrtick_update(rq);
1025 }
1026
1027 /*
1028  * sched_yield() support is very simple - we dequeue and enqueue.
1029  *
1030  * If compat_yield is turned on then we requeue to the end of the tree.
1031  */
1032 static void yield_task_fair(struct rq *rq)
1033 {
1034         struct task_struct *curr = rq->curr;
1035         struct cfs_rq *cfs_rq = task_cfs_rq(curr);
1036         struct sched_entity *rightmost, *se = &curr->se;
1037
1038         /*
1039          * Are we the only task in the tree?
1040          */
1041         if (unlikely(cfs_rq->nr_running == 1))
1042                 return;
1043
1044         clear_buddies(cfs_rq, se);
1045
1046         if (likely(!sysctl_sched_compat_yield) && curr->policy != SCHED_BATCH) {
1047                 update_rq_clock(rq);
1048                 /*
1049                  * Update run-time statistics of the 'current'.
1050                  */
1051                 update_curr(cfs_rq);
1052
1053                 return;
1054         }
1055         /*
1056          * Find the rightmost entry in the rbtree:
1057          */
1058         rightmost = __pick_last_entity(cfs_rq);
1059         /*
1060          * Already in the rightmost position?
1061          */
1062         if (unlikely(!rightmost || entity_before(rightmost, se)))
1063                 return;
1064
1065         /*
1066          * Minimally necessary key value to be last in the tree:
1067          * Upon rescheduling, sched_class::put_prev_task() will place
1068          * 'current' within the tree based on its new key value.
1069          */
1070         se->vruntime = rightmost->vruntime + 1;
1071 }
1072
1073 #ifdef CONFIG_SMP
1074
1075 #ifdef CONFIG_FAIR_GROUP_SCHED
1076 /*
1077  * effective_load() calculates the load change as seen from the root_task_group
1078  *
1079  * Adding load to a group doesn't make a group heavier, but can cause movement
1080  * of group shares between cpus. Assuming the shares were perfectly aligned one
1081  * can calculate the shift in shares.
1082  *
1083  * The problem is that perfectly aligning the shares is rather expensive, hence
1084  * we try to avoid doing that too often - see update_shares(), which ratelimits
1085  * this change.
1086  *
1087  * We compensate this by not only taking the current delta into account, but
1088  * also considering the delta between when the shares were last adjusted and
1089  * now.
1090  *
1091  * We still saw a performance dip, some tracing learned us that between
1092  * cgroup:/ and cgroup:/foo balancing the number of affine wakeups increased
1093  * significantly. Therefore try to bias the error in direction of failing
1094  * the affine wakeup.
1095  *
1096  */
1097 static long effective_load(struct task_group *tg, int cpu,
1098                 long wl, long wg)
1099 {
1100         struct sched_entity *se = tg->se[cpu];
1101
1102         if (!tg->parent)
1103                 return wl;
1104
1105         /*
1106          * By not taking the decrease of shares on the other cpu into
1107          * account our error leans towards reducing the affine wakeups.
1108          */
1109         if (!wl && sched_feat(ASYM_EFF_LOAD))
1110                 return wl;
1111
1112         for_each_sched_entity(se) {
1113                 long S, rw, s, a, b;
1114                 long more_w;
1115
1116                 /*
1117                  * Instead of using this increment, also add the difference
1118                  * between when the shares were last updated and now.
1119                  */
1120                 more_w = se->my_q->load.weight - se->my_q->rq_weight;
1121                 wl += more_w;
1122                 wg += more_w;
1123
1124                 S = se->my_q->tg->shares;
1125                 s = se->my_q->shares;
1126                 rw = se->my_q->rq_weight;
1127
1128                 a = S*(rw + wl);
1129                 b = S*rw + s*wg;
1130
1131                 wl = s*(a-b);
1132
1133                 if (likely(b))
1134                         wl /= b;
1135
1136                 /*
1137                  * Assume the group is already running and will
1138                  * thus already be accounted for in the weight.
1139                  *
1140                  * That is, moving shares between CPUs, does not
1141                  * alter the group weight.
1142                  */
1143                 wg = 0;
1144         }
1145
1146         return wl;
1147 }
1148
1149 #else
1150
1151 static inline unsigned long effective_load(struct task_group *tg, int cpu,
1152                 unsigned long wl, unsigned long wg)
1153 {
1154         return wl;
1155 }
1156
1157 #endif
1158
1159 static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
1160 {
1161         struct task_struct *curr = current;
1162         unsigned long this_load, load;
1163         int idx, this_cpu, prev_cpu;
1164         unsigned long tl_per_task;
1165         unsigned int imbalance;
1166         struct task_group *tg;
1167         unsigned long weight;
1168         int balanced;
1169
1170         idx       = sd->wake_idx;
1171         this_cpu  = smp_processor_id();
1172         prev_cpu  = task_cpu(p);
1173         load      = source_load(prev_cpu, idx);
1174         this_load = target_load(this_cpu, idx);
1175
1176         if (sync) {
1177                if (sched_feat(SYNC_LESS) &&
1178                    (curr->se.avg_overlap > sysctl_sched_migration_cost ||
1179                     p->se.avg_overlap > sysctl_sched_migration_cost))
1180                        sync = 0;
1181         } else {
1182                 if (sched_feat(SYNC_MORE) &&
1183                     (curr->se.avg_overlap < sysctl_sched_migration_cost &&
1184                      p->se.avg_overlap < sysctl_sched_migration_cost))
1185                         sync = 1;
1186         }
1187
1188         /*
1189          * If sync wakeup then subtract the (maximum possible)
1190          * effect of the currently running task from the load
1191          * of the current CPU:
1192          */
1193         if (sync) {
1194                 tg = task_group(current);
1195                 weight = current->se.load.weight;
1196
1197                 this_load += effective_load(tg, this_cpu, -weight, -weight);
1198                 load += effective_load(tg, prev_cpu, 0, -weight);
1199         }
1200
1201         tg = task_group(p);
1202         weight = p->se.load.weight;
1203
1204         imbalance = 100 + (sd->imbalance_pct - 100) / 2;
1205
1206         /*
1207          * In low-load situations, where prev_cpu is idle and this_cpu is idle
1208          * due to the sync cause above having dropped this_load to 0, we'll
1209          * always have an imbalance, but there's really nothing you can do
1210          * about that, so that's good too.
1211          *
1212          * Otherwise check if either cpus are near enough in load to allow this
1213          * task to be woken on this_cpu.
1214          */
1215         balanced = !this_load ||
1216                 100*(this_load + effective_load(tg, this_cpu, weight, weight)) <=
1217                 imbalance*(load + effective_load(tg, prev_cpu, 0, weight));
1218
1219         /*
1220          * If the currently running task will sleep within
1221          * a reasonable amount of time then attract this newly
1222          * woken task:
1223          */
1224         if (sync && balanced)
1225                 return 1;
1226
1227         schedstat_inc(p, se.nr_wakeups_affine_attempts);
1228         tl_per_task = cpu_avg_load_per_task(this_cpu);
1229
1230         if (balanced ||
1231             (this_load <= load &&
1232              this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
1233                 /*
1234                  * This domain has SD_WAKE_AFFINE and
1235                  * p is cache cold in this domain, and
1236                  * there is no bad imbalance.
1237                  */
1238                 schedstat_inc(sd, ttwu_move_affine);
1239                 schedstat_inc(p, se.nr_wakeups_affine);
1240
1241                 return 1;
1242         }
1243         return 0;
1244 }
1245
1246 /*
1247  * find_idlest_group finds and returns the least busy CPU group within the
1248  * domain.
1249  */
1250 static struct sched_group *
1251 find_idlest_group(struct sched_domain *sd, struct task_struct *p,
1252                   int this_cpu, int load_idx)
1253 {
1254         struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups;
1255         unsigned long min_load = ULONG_MAX, this_load = 0;
1256         int imbalance = 100 + (sd->imbalance_pct-100)/2;
1257
1258         do {
1259                 unsigned long load, avg_load;
1260                 int local_group;
1261                 int i;
1262
1263                 /* Skip over this group if it has no CPUs allowed */
1264                 if (!cpumask_intersects(sched_group_cpus(group),
1265                                         &p->cpus_allowed))
1266                         continue;
1267
1268                 local_group = cpumask_test_cpu(this_cpu,
1269                                                sched_group_cpus(group));
1270
1271                 /* Tally up the load of all CPUs in the group */
1272                 avg_load = 0;
1273
1274                 for_each_cpu(i, sched_group_cpus(group)) {
1275                         /* Bias balancing toward cpus of our domain */
1276                         if (local_group)
1277                                 load = source_load(i, load_idx);
1278                         else
1279                                 load = target_load(i, load_idx);
1280
1281                         avg_load += load;
1282                 }
1283
1284                 /* Adjust by relative CPU power of the group */
1285                 avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
1286
1287                 if (local_group) {
1288                         this_load = avg_load;
1289                         this = group;
1290                 } else if (avg_load < min_load) {
1291                         min_load = avg_load;
1292                         idlest = group;
1293                 }
1294         } while (group = group->next, group != sd->groups);
1295
1296         if (!idlest || 100*this_load < imbalance*min_load)
1297                 return NULL;
1298         return idlest;
1299 }
1300
1301 /*
1302  * find_idlest_cpu - find the idlest cpu among the cpus in group.
1303  */
1304 static int
1305 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
1306 {
1307         unsigned long load, min_load = ULONG_MAX;
1308         int idlest = -1;
1309         int i;
1310
1311         /* Traverse only the allowed CPUs */
1312         for_each_cpu_and(i, sched_group_cpus(group), &p->cpus_allowed) {
1313                 load = weighted_cpuload(i);
1314
1315                 if (load < min_load || (load == min_load && i == this_cpu)) {
1316                         min_load = load;
1317                         idlest = i;
1318                 }
1319         }
1320
1321         return idlest;
1322 }
1323
1324 /*
1325  * sched_balance_self: balance the current task (running on cpu) in domains
1326  * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1327  * SD_BALANCE_EXEC.
1328  *
1329  * Balance, ie. select the least loaded group.
1330  *
1331  * Returns the target CPU number, or the same CPU if no balancing is needed.
1332  *
1333  * preempt must be disabled.
1334  */
1335 static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
1336 {
1337         struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
1338         int cpu = smp_processor_id();
1339         int prev_cpu = task_cpu(p);
1340         int new_cpu = cpu;
1341         int want_affine = 0;
1342         int want_sd = 1;
1343         int sync = wake_flags & WF_SYNC;
1344
1345         if (sd_flag & SD_BALANCE_WAKE) {
1346                 if (sched_feat(AFFINE_WAKEUPS))
1347                         want_affine = 1;
1348                 new_cpu = prev_cpu;
1349         }
1350
1351         rcu_read_lock();
1352         for_each_domain(cpu, tmp) {
1353                 /*
1354                  * If power savings logic is enabled for a domain, see if we
1355                  * are not overloaded, if so, don't balance wider.
1356                  */
1357                 if (tmp->flags & (SD_POWERSAVINGS_BALANCE|SD_PREFER_LOCAL)) {
1358                         unsigned long power = 0;
1359                         unsigned long nr_running = 0;
1360                         unsigned long capacity;
1361                         int i;
1362
1363                         for_each_cpu(i, sched_domain_span(tmp)) {
1364                                 power += power_of(i);
1365                                 nr_running += cpu_rq(i)->cfs.nr_running;
1366                         }
1367
1368                         capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
1369
1370                         if (tmp->flags & SD_POWERSAVINGS_BALANCE)
1371                                 nr_running /= 2;
1372
1373                         if (nr_running < capacity)
1374                                 want_sd = 0;
1375                 }
1376
1377                 if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
1378                     cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
1379
1380                         affine_sd = tmp;
1381                         want_affine = 0;
1382                 }
1383
1384                 if (!want_sd && !want_affine)
1385                         break;
1386
1387                 if (!(tmp->flags & sd_flag))
1388                         continue;
1389
1390                 if (want_sd)
1391                         sd = tmp;
1392         }
1393
1394         if (sched_feat(LB_SHARES_UPDATE)) {
1395                 /*
1396                  * Pick the largest domain to update shares over
1397                  */
1398                 tmp = sd;
1399                 if (affine_sd && (!tmp ||
1400                                   cpumask_weight(sched_domain_span(affine_sd)) >
1401                                   cpumask_weight(sched_domain_span(sd))))
1402                         tmp = affine_sd;
1403
1404                 if (tmp)
1405                         update_shares(tmp);
1406         }
1407
1408         if (affine_sd && wake_affine(affine_sd, p, sync)) {
1409                 new_cpu = cpu;
1410                 goto out;
1411         }
1412
1413         while (sd) {
1414                 int load_idx = sd->forkexec_idx;
1415                 struct sched_group *group;
1416                 int weight;
1417
1418                 if (!(sd->flags & sd_flag)) {
1419                         sd = sd->child;
1420                         continue;
1421                 }
1422
1423                 if (sd_flag & SD_BALANCE_WAKE)
1424                         load_idx = sd->wake_idx;
1425
1426                 group = find_idlest_group(sd, p, cpu, load_idx);
1427                 if (!group) {
1428                         sd = sd->child;
1429                         continue;
1430                 }
1431
1432                 new_cpu = find_idlest_cpu(group, p, cpu);
1433                 if (new_cpu == -1 || new_cpu == cpu) {
1434                         /* Now try balancing at a lower domain level of cpu */
1435                         sd = sd->child;
1436                         continue;
1437                 }
1438
1439                 /* Now try balancing at a lower domain level of new_cpu */
1440                 cpu = new_cpu;
1441                 weight = cpumask_weight(sched_domain_span(sd));
1442                 sd = NULL;
1443                 for_each_domain(cpu, tmp) {
1444                         if (weight <= cpumask_weight(sched_domain_span(tmp)))
1445                                 break;
1446                         if (tmp->flags & sd_flag)
1447                                 sd = tmp;
1448                 }
1449                 /* while loop will break here if sd == NULL */
1450         }
1451
1452 out:
1453         rcu_read_unlock();
1454         return new_cpu;
1455 }
1456 #endif /* CONFIG_SMP */
1457
1458 /*
1459  * Adaptive granularity
1460  *
1461  * se->avg_wakeup gives the average time a task runs until it does a wakeup,
1462  * with the limit of wakeup_gran -- when it never does a wakeup.
1463  *
1464  * So the smaller avg_wakeup is the faster we want this task to preempt,
1465  * but we don't want to treat the preemptee unfairly and therefore allow it
1466  * to run for at least the amount of time we'd like to run.
1467  *
1468  * NOTE: we use 2*avg_wakeup to increase the probability of actually doing one
1469  *
1470  * NOTE: we use *nr_running to scale with load, this nicely matches the
1471  *       degrading latency on load.
1472  */
1473 static unsigned long
1474 adaptive_gran(struct sched_entity *curr, struct sched_entity *se)
1475 {
1476         u64 this_run = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
1477         u64 expected_wakeup = 2*se->avg_wakeup * cfs_rq_of(se)->nr_running;
1478         u64 gran = 0;
1479
1480         if (this_run < expected_wakeup)
1481                 gran = expected_wakeup - this_run;
1482
1483         return min_t(s64, gran, sysctl_sched_wakeup_granularity);
1484 }
1485
1486 static unsigned long
1487 wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
1488 {
1489         unsigned long gran = sysctl_sched_wakeup_granularity;
1490
1491         if (cfs_rq_of(curr)->curr && sched_feat(ADAPTIVE_GRAN))
1492                 gran = adaptive_gran(curr, se);
1493
1494         /*
1495          * Since its curr running now, convert the gran from real-time
1496          * to virtual-time in his units.
1497          */
1498         if (sched_feat(ASYM_GRAN)) {
1499                 /*
1500                  * By using 'se' instead of 'curr' we penalize light tasks, so
1501                  * they get preempted easier. That is, if 'se' < 'curr' then
1502                  * the resulting gran will be larger, therefore penalizing the
1503                  * lighter, if otoh 'se' > 'curr' then the resulting gran will
1504                  * be smaller, again penalizing the lighter task.
1505                  *
1506                  * This is especially important for buddies when the leftmost
1507                  * task is higher priority than the buddy.
1508                  */
1509                 if (unlikely(se->load.weight != NICE_0_LOAD))
1510                         gran = calc_delta_fair(gran, se);
1511         } else {
1512                 if (unlikely(curr->load.weight != NICE_0_LOAD))
1513                         gran = calc_delta_fair(gran, curr);
1514         }
1515
1516         return gran;
1517 }
1518
1519 /*
1520  * Should 'se' preempt 'curr'.
1521  *
1522  *             |s1
1523  *        |s2
1524  *   |s3
1525  *         g
1526  *      |<--->|c
1527  *
1528  *  w(c, s1) = -1
1529  *  w(c, s2) =  0
1530  *  w(c, s3) =  1
1531  *
1532  */
1533 static int
1534 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
1535 {
1536         s64 gran, vdiff = curr->vruntime - se->vruntime;
1537
1538         if (vdiff <= 0)
1539                 return -1;
1540
1541         gran = wakeup_gran(curr, se);
1542         if (vdiff > gran)
1543                 return 1;
1544
1545         return 0;
1546 }
1547
1548 static void set_last_buddy(struct sched_entity *se)
1549 {
1550         if (likely(task_of(se)->policy != SCHED_IDLE)) {
1551                 for_each_sched_entity(se)
1552                         cfs_rq_of(se)->last = se;
1553         }
1554 }
1555
1556 static void set_next_buddy(struct sched_entity *se)
1557 {
1558         if (likely(task_of(se)->policy != SCHED_IDLE)) {
1559                 for_each_sched_entity(se)
1560                         cfs_rq_of(se)->next = se;
1561         }
1562 }
1563
1564 /*
1565  * Preempt the current task with a newly woken task if needed:
1566  */
1567 static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1568 {
1569         struct task_struct *curr = rq->curr;
1570         struct sched_entity *se = &curr->se, *pse = &p->se;
1571         struct cfs_rq *cfs_rq = task_cfs_rq(curr);
1572         int sync = wake_flags & WF_SYNC;
1573
1574         update_curr(cfs_rq);
1575
1576         if (unlikely(rt_prio(p->prio))) {
1577                 resched_task(curr);
1578                 return;
1579         }
1580
1581         if (unlikely(p->sched_class != &fair_sched_class))
1582                 return;
1583
1584         if (unlikely(se == pse))
1585                 return;
1586
1587         /*
1588          * Only set the backward buddy when the current task is still on the
1589          * rq. This can happen when a wakeup gets interleaved with schedule on
1590          * the ->pre_schedule() or idle_balance() point, either of which can
1591          * drop the rq lock.
1592          *
1593          * Also, during early boot the idle thread is in the fair class, for
1594          * obvious reasons its a bad idea to schedule back to the idle thread.
1595          */
1596         if (sched_feat(LAST_BUDDY) && likely(se->on_rq && curr != rq->idle))
1597                 set_last_buddy(se);
1598         if (sched_feat(NEXT_BUDDY) && !(wake_flags & WF_FORK))
1599                 set_next_buddy(pse);
1600
1601         /*
1602          * We can come here with TIF_NEED_RESCHED already set from new task
1603          * wake up path.
1604          */
1605         if (test_tsk_need_resched(curr))
1606                 return;
1607
1608         /*
1609          * Batch and idle tasks do not preempt (their preemption is driven by
1610          * the tick):
1611          */
1612         if (unlikely(p->policy != SCHED_NORMAL))
1613                 return;
1614
1615         /* Idle tasks are by definition preempted by everybody. */
1616         if (unlikely(curr->policy == SCHED_IDLE)) {
1617                 resched_task(curr);
1618                 return;
1619         }
1620
1621         if ((sched_feat(WAKEUP_SYNC) && sync) ||
1622             (sched_feat(WAKEUP_OVERLAP) &&
1623              (se->avg_overlap < sysctl_sched_migration_cost &&
1624               pse->avg_overlap < sysctl_sched_migration_cost))) {
1625                 resched_task(curr);
1626                 return;
1627         }
1628
1629         if (sched_feat(WAKEUP_RUNNING)) {
1630                 if (pse->avg_running < se->avg_running) {
1631                         set_next_buddy(pse);
1632                         resched_task(curr);
1633                         return;
1634                 }
1635         }
1636
1637         if (!sched_feat(WAKEUP_PREEMPT))
1638                 return;
1639
1640         find_matching_se(&se, &pse);
1641
1642         BUG_ON(!pse);
1643
1644         if (wakeup_preempt_entity(se, pse) == 1)
1645                 resched_task(curr);
1646 }
1647
1648 static struct task_struct *pick_next_task_fair(struct rq *rq)
1649 {
1650         struct task_struct *p;
1651         struct cfs_rq *cfs_rq = &rq->cfs;
1652         struct sched_entity *se;
1653
1654         if (unlikely(!cfs_rq->nr_running))
1655                 return NULL;
1656
1657         do {
1658                 se = pick_next_entity(cfs_rq);
1659                 /*
1660                  * If se was a buddy, clear it so that it will have to earn
1661                  * the favour again.
1662                  *
1663                  * If se was not a buddy, clear the buddies because neither
1664                  * was elegible to run, let them earn it again.
1665                  *
1666                  * IOW. unconditionally clear buddies.
1667                  */
1668                 __clear_buddies(cfs_rq, NULL);
1669                 set_next_entity(cfs_rq, se);
1670                 cfs_rq = group_cfs_rq(se);
1671         } while (cfs_rq);
1672
1673         p = task_of(se);
1674         hrtick_start_fair(rq, p);
1675
1676         return p;
1677 }
1678
1679 /*
1680  * Account for a descheduled task:
1681  */
1682 static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
1683 {
1684         struct sched_entity *se = &prev->se;
1685         struct cfs_rq *cfs_rq;
1686
1687         for_each_sched_entity(se) {
1688                 cfs_rq = cfs_rq_of(se);
1689                 put_prev_entity(cfs_rq, se);
1690         }
1691 }
1692
1693 #ifdef CONFIG_SMP
1694 /**************************************************
1695  * Fair scheduling class load-balancing methods:
1696  */
1697
1698 /*
1699  * Load-balancing iterator. Note: while the runqueue stays locked
1700  * during the whole iteration, the current task might be
1701  * dequeued so the iterator has to be dequeue-safe. Here we
1702  * achieve that by always pre-iterating before returning
1703  * the current task:
1704  */
1705 static struct task_struct *
1706 __load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
1707 {
1708         struct task_struct *p = NULL;
1709         struct sched_entity *se;
1710
1711         if (next == &cfs_rq->tasks)
1712                 return NULL;
1713
1714         se = list_entry(next, struct sched_entity, group_node);
1715         p = task_of(se);
1716         cfs_rq->balance_iterator = next->next;
1717
1718         return p;
1719 }
1720
1721 static struct task_struct *load_balance_start_fair(void *arg)
1722 {
1723         struct cfs_rq *cfs_rq = arg;
1724
1725         return __load_balance_iterator(cfs_rq, cfs_rq->tasks.next);
1726 }
1727
1728 static struct task_struct *load_balance_next_fair(void *arg)
1729 {
1730         struct cfs_rq *cfs_rq = arg;
1731
1732         return __load_balance_iterator(cfs_rq, cfs_rq->balance_iterator);
1733 }
1734
1735 static unsigned long
1736 __load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
1737                 unsigned long max_load_move, struct sched_domain *sd,
1738                 enum cpu_idle_type idle, int *all_pinned, int *this_best_prio,
1739                 struct cfs_rq *cfs_rq)
1740 {
1741         struct rq_iterator cfs_rq_iterator;
1742
1743         cfs_rq_iterator.start = load_balance_start_fair;
1744         cfs_rq_iterator.next = load_balance_next_fair;
1745         cfs_rq_iterator.arg = cfs_rq;
1746
1747         return balance_tasks(this_rq, this_cpu, busiest,
1748                         max_load_move, sd, idle, all_pinned,
1749                         this_best_prio, &cfs_rq_iterator);
1750 }
1751
1752 #ifdef CONFIG_FAIR_GROUP_SCHED
1753 static unsigned long
1754 load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
1755                   unsigned long max_load_move,
1756                   struct sched_domain *sd, enum cpu_idle_type idle,
1757                   int *all_pinned, int *this_best_prio)
1758 {
1759         long rem_load_move = max_load_move;
1760         int busiest_cpu = cpu_of(busiest);
1761         struct task_group *tg;
1762
1763         rcu_read_lock();
1764         update_h_load(busiest_cpu);
1765
1766         list_for_each_entry_rcu(tg, &task_groups, list) {
1767                 struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu];
1768                 unsigned long busiest_h_load = busiest_cfs_rq->h_load;
1769                 unsigned long busiest_weight = busiest_cfs_rq->load.weight;
1770                 u64 rem_load, moved_load;
1771
1772                 /*
1773                  * empty group
1774                  */
1775                 if (!busiest_cfs_rq->task_weight)
1776                         continue;
1777
1778                 rem_load = (u64)rem_load_move * busiest_weight;
1779                 rem_load = div_u64(rem_load, busiest_h_load + 1);
1780
1781                 moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
1782                                 rem_load, sd, idle, all_pinned, this_best_prio,
1783                                 tg->cfs_rq[busiest_cpu]);
1784
1785                 if (!moved_load)
1786                         continue;
1787
1788                 moved_load *= busiest_h_load;
1789                 moved_load = div_u64(moved_load, busiest_weight + 1);
1790
1791                 rem_load_move -= moved_load;
1792                 if (rem_load_move < 0)
1793                         break;
1794         }
1795         rcu_read_unlock();
1796
1797         return max_load_move - rem_load_move;
1798 }
1799 #else
1800 static unsigned long
1801 load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
1802                   unsigned long max_load_move,
1803                   struct sched_domain *sd, enum cpu_idle_type idle,
1804                   int *all_pinned, int *this_best_prio)
1805 {
1806         return __load_balance_fair(this_rq, this_cpu, busiest,
1807                         max_load_move, sd, idle, all_pinned,
1808                         this_best_prio, &busiest->cfs);
1809 }
1810 #endif
1811
1812 static int
1813 move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
1814                    struct sched_domain *sd, enum cpu_idle_type idle)
1815 {
1816         struct cfs_rq *busy_cfs_rq;
1817         struct rq_iterator cfs_rq_iterator;
1818
1819         cfs_rq_iterator.start = load_balance_start_fair;
1820         cfs_rq_iterator.next = load_balance_next_fair;
1821
1822         for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
1823                 /*
1824                  * pass busy_cfs_rq argument into
1825                  * load_balance_[start|next]_fair iterators
1826                  */
1827                 cfs_rq_iterator.arg = busy_cfs_rq;
1828                 if (iter_move_one_task(this_rq, this_cpu, busiest, sd, idle,
1829                                        &cfs_rq_iterator))
1830                     return 1;
1831         }
1832
1833         return 0;
1834 }
1835 #endif /* CONFIG_SMP */
1836
1837 /*
1838  * scheduler tick hitting a task of our scheduling class:
1839  */
1840 static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
1841 {
1842         struct cfs_rq *cfs_rq;
1843         struct sched_entity *se = &curr->se;
1844
1845         for_each_sched_entity(se) {
1846                 cfs_rq = cfs_rq_of(se);
1847                 entity_tick(cfs_rq, se, queued);
1848         }
1849 }
1850
1851 /*
1852  * Share the fairness runtime between parent and child, thus the
1853  * total amount of pressure for CPU stays equal - new tasks
1854  * get a chance to run but frequent forkers are not allowed to
1855  * monopolize the CPU. Note: the parent runqueue is locked,
1856  * the child is not running yet.
1857  */
1858 static void task_new_fair(struct rq *rq, struct task_struct *p)
1859 {
1860         struct cfs_rq *cfs_rq = task_cfs_rq(p);
1861         struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
1862         int this_cpu = smp_processor_id();
1863
1864         sched_info_queued(p);
1865
1866         update_curr(cfs_rq);
1867         if (curr)
1868                 se->vruntime = curr->vruntime;
1869         place_entity(cfs_rq, se, 1);
1870
1871         /* 'curr' will be NULL if the child belongs to a different group */
1872         if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) &&
1873                         curr && entity_before(curr, se)) {
1874                 /*
1875                  * Upon rescheduling, sched_class::put_prev_task() will place
1876                  * 'current' within the tree based on its new key value.
1877                  */
1878                 swap(curr->vruntime, se->vruntime);
1879                 resched_task(rq->curr);
1880         }
1881
1882         enqueue_task_fair(rq, p, 0);
1883 }
1884
1885 /*
1886  * Priority of the task has changed. Check to see if we preempt
1887  * the current task.
1888  */
1889 static void prio_changed_fair(struct rq *rq, struct task_struct *p,
1890                               int oldprio, int running)
1891 {
1892         /*
1893          * Reschedule if we are currently running on this runqueue and
1894          * our priority decreased, or if we are not currently running on
1895          * this runqueue and our priority is higher than the current's
1896          */
1897         if (running) {
1898                 if (p->prio > oldprio)
1899                         resched_task(rq->curr);
1900         } else
1901                 check_preempt_curr(rq, p, 0);
1902 }
1903
1904 /*
1905  * We switched to the sched_fair class.
1906  */
1907 static void switched_to_fair(struct rq *rq, struct task_struct *p,
1908                              int running)
1909 {
1910         /*
1911          * We were most likely switched from sched_rt, so
1912          * kick off the schedule if running, otherwise just see
1913          * if we can still preempt the current task.
1914          */
1915         if (running)
1916                 resched_task(rq->curr);
1917         else
1918                 check_preempt_curr(rq, p, 0);
1919 }
1920
1921 /* Account for a task changing its policy or group.
1922  *
1923  * This routine is mostly called to set cfs_rq->curr field when a task
1924  * migrates between groups/classes.
1925  */
1926 static void set_curr_task_fair(struct rq *rq)
1927 {
1928         struct sched_entity *se = &rq->curr->se;
1929
1930         for_each_sched_entity(se)
1931                 set_next_entity(cfs_rq_of(se), se);
1932 }
1933
1934 #ifdef CONFIG_FAIR_GROUP_SCHED
1935 static void moved_group_fair(struct task_struct *p)
1936 {
1937         struct cfs_rq *cfs_rq = task_cfs_rq(p);
1938
1939         update_curr(cfs_rq);
1940         place_entity(cfs_rq, &p->se, 1);
1941 }
1942 #endif
1943
1944 /*
1945  * All the scheduling class methods:
1946  */
1947 static const struct sched_class fair_sched_class = {
1948         .next                   = &idle_sched_class,
1949         .enqueue_task           = enqueue_task_fair,
1950         .dequeue_task           = dequeue_task_fair,
1951         .yield_task             = yield_task_fair,
1952
1953         .check_preempt_curr     = check_preempt_wakeup,
1954
1955         .pick_next_task         = pick_next_task_fair,
1956         .put_prev_task          = put_prev_task_fair,
1957
1958 #ifdef CONFIG_SMP
1959         .select_task_rq         = select_task_rq_fair,
1960
1961         .load_balance           = load_balance_fair,
1962         .move_one_task          = move_one_task_fair,
1963 #endif
1964
1965         .set_curr_task          = set_curr_task_fair,
1966         .task_tick              = task_tick_fair,
1967         .task_new               = task_new_fair,
1968
1969         .prio_changed           = prio_changed_fair,
1970         .switched_to            = switched_to_fair,
1971
1972 #ifdef CONFIG_FAIR_GROUP_SCHED
1973         .moved_group            = moved_group_fair,
1974 #endif
1975 };
1976
1977 #ifdef CONFIG_SCHED_DEBUG
1978 static void print_cfs_stats(struct seq_file *m, int cpu)
1979 {
1980         struct cfs_rq *cfs_rq;
1981
1982         rcu_read_lock();
1983         for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
1984                 print_cfs_rq(m, cpu, cfs_rq);
1985         rcu_read_unlock();
1986 }
1987 #endif