2 * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH)
4 * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
6 * Interactivity improvements by Mike Galbraith
7 * (C) 2007 Mike Galbraith <efault@gmx.de>
9 * Various enhancements by Dmitry Adamushko.
10 * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com>
12 * Group scheduling enhancements by Srivatsa Vaddagiri
13 * Copyright IBM Corporation, 2007
14 * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
16 * Scaled math optimizations by Thomas Gleixner
17 * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de>
19 * Adaptive scheduling granularity, math enhancements by Peter Zijlstra
20 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
24 * Targeted preemption latency for CPU-bound tasks:
25 * (default: 20ms, units: nanoseconds)
27 * NOTE: this latency value is not the same as the concept of
28 * 'timeslice length' - timeslices in CFS are of variable length.
29 * (to see the precise effective timeslice length of your workload,
30 * run vmstat and monitor the context-switches field)
32 * On SMP systems the value of this is multiplied by the log2 of the
33 * number of CPUs. (i.e. factor 2x on 2-way systems, 3x on 4-way
34 * systems, 4x on 8-way systems, 5x on 16-way systems, etc.)
35 * Targeted preemption latency for CPU-bound tasks:
37 const_debug unsigned int sysctl_sched_latency = 20000000ULL;
40 * After fork, child runs first. (default) If set to 0 then
41 * parent will (try to) run first.
43 const_debug unsigned int sysctl_sched_child_runs_first = 1;
46 * Minimal preemption granularity for CPU-bound tasks:
47 * (default: 2 msec, units: nanoseconds)
49 unsigned int sysctl_sched_min_granularity __read_mostly = 2000000ULL;
52 * sys_sched_yield() compat mode
54 * This option switches the agressive yield implementation of the
55 * old scheduler back on.
57 unsigned int __read_mostly sysctl_sched_compat_yield;
60 * SCHED_BATCH wake-up granularity.
61 * (default: 25 msec, units: nanoseconds)
63 * This option delays the preemption effects of decoupled workloads
64 * and reduces their over-scheduling. Synchronous workloads will still
65 * have immediate wakeup/sleep latencies.
67 const_debug unsigned int sysctl_sched_batch_wakeup_granularity = 25000000UL;
70 * SCHED_OTHER wake-up granularity.
71 * (default: 1 msec, units: nanoseconds)
73 * This option delays the preemption effects of decoupled workloads
74 * and reduces their over-scheduling. Synchronous workloads will still
75 * have immediate wakeup/sleep latencies.
77 const_debug unsigned int sysctl_sched_wakeup_granularity = 2000000UL;
79 unsigned int sysctl_sched_runtime_limit __read_mostly;
81 extern struct sched_class fair_sched_class;
83 /**************************************************************
84 * CFS operations on generic schedulable entities:
87 #ifdef CONFIG_FAIR_GROUP_SCHED
89 /* cpu runqueue to which this cfs_rq is attached */
90 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
95 /* An entity is a task if it doesn't "own" a runqueue */
96 #define entity_is_task(se) (!se->my_q)
98 #else /* CONFIG_FAIR_GROUP_SCHED */
100 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
102 return container_of(cfs_rq, struct rq, cfs);
105 #define entity_is_task(se) 1
107 #endif /* CONFIG_FAIR_GROUP_SCHED */
109 static inline struct task_struct *task_of(struct sched_entity *se)
111 return container_of(se, struct task_struct, se);
115 /**************************************************************
116 * Scheduling class tree data structure manipulation methods:
120 max_vruntime(u64 min_vruntime, u64 vruntime)
122 if ((vruntime > min_vruntime) ||
123 (min_vruntime > (1ULL << 61) && vruntime < (1ULL << 50)))
124 min_vruntime = vruntime;
130 set_leftmost(struct cfs_rq *cfs_rq, struct rb_node *leftmost)
132 struct sched_entity *se;
134 cfs_rq->rb_leftmost = leftmost;
136 se = rb_entry(leftmost, struct sched_entity, run_node);
140 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
142 return se->fair_key - cfs_rq->min_vruntime;
146 * Enqueue an entity into the rb-tree:
149 __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
151 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
152 struct rb_node *parent = NULL;
153 struct sched_entity *entry;
154 s64 key = entity_key(cfs_rq, se);
158 * Find the right place in the rbtree:
162 entry = rb_entry(parent, struct sched_entity, run_node);
164 * We dont care about collisions. Nodes with
165 * the same key stay together.
167 if (key < entity_key(cfs_rq, entry)) {
168 link = &parent->rb_left;
170 link = &parent->rb_right;
176 * Maintain a cache of leftmost tree entries (it is frequently
180 set_leftmost(cfs_rq, &se->run_node);
182 rb_link_node(&se->run_node, parent, link);
183 rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
184 update_load_add(&cfs_rq->load, se->load.weight);
185 cfs_rq->nr_running++;
190 __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
192 if (cfs_rq->rb_leftmost == &se->run_node)
193 set_leftmost(cfs_rq, rb_next(&se->run_node));
195 rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
196 update_load_sub(&cfs_rq->load, se->load.weight);
197 cfs_rq->nr_running--;
201 static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq)
203 return cfs_rq->rb_leftmost;
206 static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
208 return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node);
211 static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
213 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
214 struct sched_entity *se = NULL;
215 struct rb_node *parent;
219 se = rb_entry(parent, struct sched_entity, run_node);
220 link = &parent->rb_right;
226 /**************************************************************
227 * Scheduling class statistics methods:
230 static u64 __sched_period(unsigned long nr_running)
232 u64 period = sysctl_sched_latency;
233 unsigned long nr_latency =
234 sysctl_sched_latency / sysctl_sched_min_granularity;
236 if (unlikely(nr_running > nr_latency)) {
237 period *= nr_running;
238 do_div(period, nr_latency);
244 static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
246 u64 period = __sched_period(cfs_rq->nr_running);
248 period *= se->load.weight;
249 do_div(period, cfs_rq->load.weight);
255 * Update the current task's runtime statistics. Skip current tasks that
256 * are not in our scheduling class.
259 __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
260 unsigned long delta_exec)
262 unsigned long delta_exec_weighted;
263 u64 next_vruntime, min_vruntime;
265 schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
267 curr->sum_exec_runtime += delta_exec;
268 schedstat_add(cfs_rq, exec_clock, delta_exec);
269 delta_exec_weighted = delta_exec;
270 if (unlikely(curr->load.weight != NICE_0_LOAD)) {
271 delta_exec_weighted = calc_delta_fair(delta_exec_weighted,
274 curr->vruntime += delta_exec_weighted;
277 * maintain cfs_rq->min_vruntime to be a monotonic increasing
278 * value tracking the leftmost vruntime in the tree.
280 if (first_fair(cfs_rq)) {
281 next_vruntime = __pick_next_entity(cfs_rq)->vruntime;
283 /* min_vruntime() := !max_vruntime() */
284 min_vruntime = max_vruntime(curr->vruntime, next_vruntime);
285 if (min_vruntime == next_vruntime)
286 min_vruntime = curr->vruntime;
288 min_vruntime = next_vruntime;
290 min_vruntime = curr->vruntime;
292 cfs_rq->min_vruntime =
293 max_vruntime(cfs_rq->min_vruntime, min_vruntime);
296 static void update_curr(struct cfs_rq *cfs_rq)
298 struct sched_entity *curr = cfs_rq->curr;
299 u64 now = rq_of(cfs_rq)->clock;
300 unsigned long delta_exec;
306 * Get the amount of time the current task was running
307 * since the last time we changed load (this cannot
308 * overflow on 32 bits):
310 delta_exec = (unsigned long)(now - curr->exec_start);
312 __update_curr(cfs_rq, curr, delta_exec);
313 curr->exec_start = now;
317 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
319 schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
322 static inline unsigned long
323 calc_weighted(unsigned long delta, struct sched_entity *se)
325 unsigned long weight = se->load.weight;
327 if (unlikely(weight != NICE_0_LOAD))
328 return (u64)delta * se->load.weight >> NICE_0_SHIFT;
334 * Task is being enqueued - update stats:
336 static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
339 * Are we enqueueing a waiting task? (for current tasks
340 * a dequeue/enqueue event is a NOP)
342 if (se != cfs_rq->curr)
343 update_stats_wait_start(cfs_rq, se);
347 se->fair_key = se->vruntime;
351 update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
353 schedstat_set(se->wait_max, max(se->wait_max,
354 rq_of(cfs_rq)->clock - se->wait_start));
355 schedstat_set(se->wait_start, 0);
359 update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
363 * Mark the end of the wait period if dequeueing a
366 if (se != cfs_rq->curr)
367 update_stats_wait_end(cfs_rq, se);
371 * We are picking a new current task - update its stats:
374 update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
377 * We are starting a new run period:
379 se->exec_start = rq_of(cfs_rq)->clock;
383 * We are descheduling a task - update its stats:
386 update_stats_curr_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
391 /**************************************************
392 * Scheduling class queueing methods:
395 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
397 #ifdef CONFIG_SCHEDSTATS
398 if (se->sleep_start) {
399 u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
404 if (unlikely(delta > se->sleep_max))
405 se->sleep_max = delta;
408 se->sum_sleep_runtime += delta;
410 if (se->block_start) {
411 u64 delta = rq_of(cfs_rq)->clock - se->block_start;
416 if (unlikely(delta > se->block_max))
417 se->block_max = delta;
420 se->sum_sleep_runtime += delta;
423 * Blocking time is in units of nanosecs, so shift by 20 to
424 * get a milliseconds-range estimation of the amount of
425 * time that the task spent sleeping:
427 if (unlikely(prof_on == SLEEP_PROFILING)) {
428 struct task_struct *tsk = task_of(se);
430 profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
438 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
440 u64 min_runtime, latency;
442 min_runtime = cfs_rq->min_vruntime;
444 if (sched_feat(USE_TREE_AVG)) {
445 struct sched_entity *last = __pick_last_entity(cfs_rq);
447 min_runtime = __pick_next_entity(cfs_rq)->vruntime;
448 min_runtime += last->vruntime;
451 } else if (sched_feat(APPROX_AVG))
452 min_runtime += sysctl_sched_latency/2;
454 if (initial && sched_feat(START_DEBIT))
455 min_runtime += sched_slice(cfs_rq, se);
457 if (!initial && sched_feat(NEW_FAIR_SLEEPERS)) {
458 latency = sysctl_sched_latency;
459 if (min_runtime > latency)
460 min_runtime -= latency;
465 se->vruntime = max(se->vruntime, min_runtime);
469 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
472 * Update the fair clock.
477 place_entity(cfs_rq, se, 0);
478 enqueue_sleeper(cfs_rq, se);
481 update_stats_enqueue(cfs_rq, se);
482 __enqueue_entity(cfs_rq, se);
486 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
488 update_stats_dequeue(cfs_rq, se);
489 #ifdef CONFIG_SCHEDSTATS
491 if (entity_is_task(se)) {
492 struct task_struct *tsk = task_of(se);
494 if (tsk->state & TASK_INTERRUPTIBLE)
495 se->sleep_start = rq_of(cfs_rq)->clock;
496 if (tsk->state & TASK_UNINTERRUPTIBLE)
497 se->block_start = rq_of(cfs_rq)->clock;
501 __dequeue_entity(cfs_rq, se);
505 * Preempt the current task with a newly woken task if needed:
508 check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
510 unsigned long ideal_runtime, delta_exec;
512 ideal_runtime = sched_slice(cfs_rq, curr);
513 delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
514 if (delta_exec > ideal_runtime)
515 resched_task(rq_of(cfs_rq)->curr);
519 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
522 * Any task has to be enqueued before it get to execute on
523 * a CPU. So account for the time it spent waiting on the
526 update_stats_wait_end(cfs_rq, se);
527 update_stats_curr_start(cfs_rq, se);
529 #ifdef CONFIG_SCHEDSTATS
531 * Track our maximum slice length, if the CPU's load is at
532 * least twice that of our own weight (i.e. dont track it
533 * when there are only lesser-weight tasks around):
535 if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
536 se->slice_max = max(se->slice_max,
537 se->sum_exec_runtime - se->prev_sum_exec_runtime);
540 se->prev_sum_exec_runtime = se->sum_exec_runtime;
543 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
545 struct sched_entity *se = __pick_next_entity(cfs_rq);
547 set_next_entity(cfs_rq, se);
552 static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
555 * If still on the runqueue then deactivate_task()
556 * was not called and update_curr() has to be done:
561 update_stats_curr_end(cfs_rq, prev);
564 update_stats_wait_start(cfs_rq, prev);
568 static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
571 * Dequeue and enqueue the task to update its
572 * position within the tree:
574 dequeue_entity(cfs_rq, curr, 0);
575 enqueue_entity(cfs_rq, curr, 0);
577 if (cfs_rq->nr_running > 1)
578 check_preempt_tick(cfs_rq, curr);
581 /**************************************************
582 * CFS operations on tasks:
585 #ifdef CONFIG_FAIR_GROUP_SCHED
587 /* Walk up scheduling entities hierarchy */
588 #define for_each_sched_entity(se) \
589 for (; se; se = se->parent)
591 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
596 /* runqueue on which this entity is (to be) queued */
597 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
602 /* runqueue "owned" by this group */
603 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
608 /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on
609 * another cpu ('this_cpu')
611 static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
613 return cfs_rq->tg->cfs_rq[this_cpu];
616 /* Iterate thr' all leaf cfs_rq's on a runqueue */
617 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
618 list_for_each_entry(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
620 /* Do the two (enqueued) tasks belong to the same group ? */
621 static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
623 if (curr->se.cfs_rq == p->se.cfs_rq)
629 #else /* CONFIG_FAIR_GROUP_SCHED */
631 #define for_each_sched_entity(se) \
632 for (; se; se = NULL)
634 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
636 return &task_rq(p)->cfs;
639 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
641 struct task_struct *p = task_of(se);
642 struct rq *rq = task_rq(p);
647 /* runqueue "owned" by this group */
648 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
653 static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
655 return &cpu_rq(this_cpu)->cfs;
658 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
659 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
661 static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
666 #endif /* CONFIG_FAIR_GROUP_SCHED */
669 * The enqueue_task method is called before nr_running is
670 * increased. Here we update the fair scheduling stats and
671 * then put the task into the rbtree:
673 static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
675 struct cfs_rq *cfs_rq;
676 struct sched_entity *se = &p->se;
678 for_each_sched_entity(se) {
681 cfs_rq = cfs_rq_of(se);
682 enqueue_entity(cfs_rq, se, wakeup);
687 * The dequeue_task method is called before nr_running is
688 * decreased. We remove the task from the rbtree and
689 * update the fair scheduling stats:
691 static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
693 struct cfs_rq *cfs_rq;
694 struct sched_entity *se = &p->se;
696 for_each_sched_entity(se) {
697 cfs_rq = cfs_rq_of(se);
698 dequeue_entity(cfs_rq, se, sleep);
699 /* Don't dequeue parent if it has other entities besides us */
700 if (cfs_rq->load.weight)
706 * sched_yield() support is very simple - we dequeue and enqueue.
708 * If compat_yield is turned on then we requeue to the end of the tree.
710 static void yield_task_fair(struct rq *rq, struct task_struct *p)
712 struct cfs_rq *cfs_rq = task_cfs_rq(p);
713 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
714 struct sched_entity *rightmost, *se = &p->se;
715 struct rb_node *parent;
718 * Are we the only task in the tree?
720 if (unlikely(cfs_rq->nr_running == 1))
723 if (likely(!sysctl_sched_compat_yield)) {
724 __update_rq_clock(rq);
726 * Dequeue and enqueue the task to update its
727 * position within the tree:
729 dequeue_entity(cfs_rq, &p->se, 0);
730 enqueue_entity(cfs_rq, &p->se, 0);
735 * Find the rightmost entry in the rbtree:
739 link = &parent->rb_right;
742 rightmost = rb_entry(parent, struct sched_entity, run_node);
744 * Already in the rightmost position?
746 if (unlikely(rightmost == se))
750 * Minimally necessary key value to be last in the tree:
752 se->fair_key = rightmost->fair_key + 1;
754 if (cfs_rq->rb_leftmost == &se->run_node)
755 cfs_rq->rb_leftmost = rb_next(&se->run_node);
757 * Relink the task to the rightmost position:
759 rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
760 rb_link_node(&se->run_node, parent, link);
761 rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
765 * Preempt the current task with a newly woken task if needed:
767 static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
769 struct task_struct *curr = rq->curr;
770 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
772 if (unlikely(rt_prio(p->prio))) {
778 if (is_same_group(curr, p)) {
779 s64 delta = curr->se.vruntime - p->se.vruntime;
781 if (delta > (s64)sysctl_sched_wakeup_granularity)
786 static struct task_struct *pick_next_task_fair(struct rq *rq)
788 struct cfs_rq *cfs_rq = &rq->cfs;
789 struct sched_entity *se;
791 if (unlikely(!cfs_rq->nr_running))
795 se = pick_next_entity(cfs_rq);
796 cfs_rq = group_cfs_rq(se);
803 * Account for a descheduled task:
805 static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
807 struct sched_entity *se = &prev->se;
808 struct cfs_rq *cfs_rq;
810 for_each_sched_entity(se) {
811 cfs_rq = cfs_rq_of(se);
812 put_prev_entity(cfs_rq, se);
816 /**************************************************
817 * Fair scheduling class load-balancing methods:
821 * Load-balancing iterator. Note: while the runqueue stays locked
822 * during the whole iteration, the current task might be
823 * dequeued so the iterator has to be dequeue-safe. Here we
824 * achieve that by always pre-iterating before returning
827 static inline struct task_struct *
828 __load_balance_iterator(struct cfs_rq *cfs_rq, struct rb_node *curr)
830 struct task_struct *p;
835 p = rb_entry(curr, struct task_struct, se.run_node);
836 cfs_rq->rb_load_balance_curr = rb_next(curr);
841 static struct task_struct *load_balance_start_fair(void *arg)
843 struct cfs_rq *cfs_rq = arg;
845 return __load_balance_iterator(cfs_rq, first_fair(cfs_rq));
848 static struct task_struct *load_balance_next_fair(void *arg)
850 struct cfs_rq *cfs_rq = arg;
852 return __load_balance_iterator(cfs_rq, cfs_rq->rb_load_balance_curr);
855 #ifdef CONFIG_FAIR_GROUP_SCHED
856 static int cfs_rq_best_prio(struct cfs_rq *cfs_rq)
858 struct sched_entity *curr;
859 struct task_struct *p;
861 if (!cfs_rq->nr_running)
864 curr = __pick_next_entity(cfs_rq);
872 load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
873 unsigned long max_nr_move, unsigned long max_load_move,
874 struct sched_domain *sd, enum cpu_idle_type idle,
875 int *all_pinned, int *this_best_prio)
877 struct cfs_rq *busy_cfs_rq;
878 unsigned long load_moved, total_nr_moved = 0, nr_moved;
879 long rem_load_move = max_load_move;
880 struct rq_iterator cfs_rq_iterator;
882 cfs_rq_iterator.start = load_balance_start_fair;
883 cfs_rq_iterator.next = load_balance_next_fair;
885 for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
886 #ifdef CONFIG_FAIR_GROUP_SCHED
887 struct cfs_rq *this_cfs_rq;
889 unsigned long maxload;
891 this_cfs_rq = cpu_cfs_rq(busy_cfs_rq, this_cpu);
893 imbalance = busy_cfs_rq->load.weight - this_cfs_rq->load.weight;
894 /* Don't pull if this_cfs_rq has more load than busy_cfs_rq */
898 /* Don't pull more than imbalance/2 */
900 maxload = min(rem_load_move, imbalance);
902 *this_best_prio = cfs_rq_best_prio(this_cfs_rq);
904 # define maxload rem_load_move
906 /* pass busy_cfs_rq argument into
907 * load_balance_[start|next]_fair iterators
909 cfs_rq_iterator.arg = busy_cfs_rq;
910 nr_moved = balance_tasks(this_rq, this_cpu, busiest,
911 max_nr_move, maxload, sd, idle, all_pinned,
912 &load_moved, this_best_prio, &cfs_rq_iterator);
914 total_nr_moved += nr_moved;
915 max_nr_move -= nr_moved;
916 rem_load_move -= load_moved;
918 if (max_nr_move <= 0 || rem_load_move <= 0)
922 return max_load_move - rem_load_move;
926 * scheduler tick hitting a task of our scheduling class:
928 static void task_tick_fair(struct rq *rq, struct task_struct *curr)
930 struct cfs_rq *cfs_rq;
931 struct sched_entity *se = &curr->se;
933 for_each_sched_entity(se) {
934 cfs_rq = cfs_rq_of(se);
935 entity_tick(cfs_rq, se);
939 #define swap(a,b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0)
942 * Share the fairness runtime between parent and child, thus the
943 * total amount of pressure for CPU stays equal - new tasks
944 * get a chance to run but frequent forkers are not allowed to
945 * monopolize the CPU. Note: the parent runqueue is locked,
946 * the child is not running yet.
948 static void task_new_fair(struct rq *rq, struct task_struct *p)
950 struct cfs_rq *cfs_rq = task_cfs_rq(p);
951 struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
953 sched_info_queued(p);
956 place_entity(cfs_rq, se, 1);
958 if (sysctl_sched_child_runs_first &&
959 curr->vruntime < se->vruntime) {
961 dequeue_entity(cfs_rq, curr, 0);
962 swap(curr->vruntime, se->vruntime);
963 enqueue_entity(cfs_rq, curr, 0);
966 update_stats_enqueue(cfs_rq, se);
967 __enqueue_entity(cfs_rq, se);
968 resched_task(rq->curr);
971 #ifdef CONFIG_FAIR_GROUP_SCHED
972 /* Account for a task changing its policy or group.
974 * This routine is mostly called to set cfs_rq->curr field when a task
975 * migrates between groups/classes.
977 static void set_curr_task_fair(struct rq *rq)
979 struct sched_entity *se = &rq->curr->se;
981 for_each_sched_entity(se)
982 set_next_entity(cfs_rq_of(se), se);
985 static void set_curr_task_fair(struct rq *rq)
987 struct sched_entity *se = &rq->curr->se;
988 struct cfs_rq *cfs_rq = cfs_rq_of(se);
995 * All the scheduling class methods:
997 struct sched_class fair_sched_class __read_mostly = {
998 .enqueue_task = enqueue_task_fair,
999 .dequeue_task = dequeue_task_fair,
1000 .yield_task = yield_task_fair,
1002 .check_preempt_curr = check_preempt_wakeup,
1004 .pick_next_task = pick_next_task_fair,
1005 .put_prev_task = put_prev_task_fair,
1007 .load_balance = load_balance_fair,
1009 .set_curr_task = set_curr_task_fair,
1010 .task_tick = task_tick_fair,
1011 .task_new = task_new_fair,
1014 #ifdef CONFIG_SCHED_DEBUG
1015 static void print_cfs_stats(struct seq_file *m, int cpu)
1017 struct cfs_rq *cfs_rq;
1019 for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
1020 print_cfs_rq(m, cpu, cfs_rq);