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->vruntime - 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);
187 __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
189 if (cfs_rq->rb_leftmost == &se->run_node)
190 set_leftmost(cfs_rq, rb_next(&se->run_node));
192 rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
195 static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq)
197 return cfs_rq->rb_leftmost;
200 static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
202 return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node);
205 static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
207 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
208 struct sched_entity *se = NULL;
209 struct rb_node *parent;
213 se = rb_entry(parent, struct sched_entity, run_node);
214 link = &parent->rb_right;
220 /**************************************************************
221 * Scheduling class statistics methods:
224 static u64 __sched_period(unsigned long nr_running)
226 u64 period = sysctl_sched_latency;
227 unsigned long nr_latency =
228 sysctl_sched_latency / sysctl_sched_min_granularity;
230 if (unlikely(nr_running > nr_latency)) {
231 period *= nr_running;
232 do_div(period, nr_latency);
238 static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
240 u64 period = __sched_period(cfs_rq->nr_running);
242 period *= se->load.weight;
243 do_div(period, cfs_rq->load.weight);
249 * Update the current task's runtime statistics. Skip current tasks that
250 * are not in our scheduling class.
253 __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
254 unsigned long delta_exec)
256 unsigned long delta_exec_weighted;
257 u64 next_vruntime, min_vruntime;
259 schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
261 curr->sum_exec_runtime += delta_exec;
262 schedstat_add(cfs_rq, exec_clock, delta_exec);
263 delta_exec_weighted = delta_exec;
264 if (unlikely(curr->load.weight != NICE_0_LOAD)) {
265 delta_exec_weighted = calc_delta_fair(delta_exec_weighted,
268 curr->vruntime += delta_exec_weighted;
271 * maintain cfs_rq->min_vruntime to be a monotonic increasing
272 * value tracking the leftmost vruntime in the tree.
274 if (first_fair(cfs_rq)) {
275 next_vruntime = __pick_next_entity(cfs_rq)->vruntime;
277 /* min_vruntime() := !max_vruntime() */
278 min_vruntime = max_vruntime(curr->vruntime, next_vruntime);
279 if (min_vruntime == next_vruntime)
280 min_vruntime = curr->vruntime;
282 min_vruntime = next_vruntime;
284 min_vruntime = curr->vruntime;
286 cfs_rq->min_vruntime =
287 max_vruntime(cfs_rq->min_vruntime, min_vruntime);
290 static void update_curr(struct cfs_rq *cfs_rq)
292 struct sched_entity *curr = cfs_rq->curr;
293 u64 now = rq_of(cfs_rq)->clock;
294 unsigned long delta_exec;
300 * Get the amount of time the current task was running
301 * since the last time we changed load (this cannot
302 * overflow on 32 bits):
304 delta_exec = (unsigned long)(now - curr->exec_start);
306 __update_curr(cfs_rq, curr, delta_exec);
307 curr->exec_start = now;
311 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
313 schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
316 static inline unsigned long
317 calc_weighted(unsigned long delta, struct sched_entity *se)
319 unsigned long weight = se->load.weight;
321 if (unlikely(weight != NICE_0_LOAD))
322 return (u64)delta * se->load.weight >> NICE_0_SHIFT;
328 * Task is being enqueued - update stats:
330 static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
333 * Are we enqueueing a waiting task? (for current tasks
334 * a dequeue/enqueue event is a NOP)
336 if (se != cfs_rq->curr)
337 update_stats_wait_start(cfs_rq, se);
341 update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
343 schedstat_set(se->wait_max, max(se->wait_max,
344 rq_of(cfs_rq)->clock - se->wait_start));
345 schedstat_set(se->wait_start, 0);
349 update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
353 * Mark the end of the wait period if dequeueing a
356 if (se != cfs_rq->curr)
357 update_stats_wait_end(cfs_rq, se);
361 * We are picking a new current task - update its stats:
364 update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
367 * We are starting a new run period:
369 se->exec_start = rq_of(cfs_rq)->clock;
373 * We are descheduling a task - update its stats:
376 update_stats_curr_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
381 /**************************************************
382 * Scheduling class queueing methods:
386 account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
388 update_load_add(&cfs_rq->load, se->load.weight);
389 cfs_rq->nr_running++;
394 account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
396 update_load_sub(&cfs_rq->load, se->load.weight);
397 cfs_rq->nr_running--;
401 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
403 #ifdef CONFIG_SCHEDSTATS
404 if (se->sleep_start) {
405 u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
410 if (unlikely(delta > se->sleep_max))
411 se->sleep_max = delta;
414 se->sum_sleep_runtime += delta;
416 if (se->block_start) {
417 u64 delta = rq_of(cfs_rq)->clock - se->block_start;
422 if (unlikely(delta > se->block_max))
423 se->block_max = delta;
426 se->sum_sleep_runtime += delta;
429 * Blocking time is in units of nanosecs, so shift by 20 to
430 * get a milliseconds-range estimation of the amount of
431 * time that the task spent sleeping:
433 if (unlikely(prof_on == SLEEP_PROFILING)) {
434 struct task_struct *tsk = task_of(se);
436 profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
444 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
446 u64 min_runtime, latency;
448 min_runtime = cfs_rq->min_vruntime;
450 if (sched_feat(USE_TREE_AVG)) {
451 struct sched_entity *last = __pick_last_entity(cfs_rq);
453 min_runtime = __pick_next_entity(cfs_rq)->vruntime;
454 min_runtime += last->vruntime;
457 } else if (sched_feat(APPROX_AVG))
458 min_runtime += sysctl_sched_latency/2;
460 if (initial && sched_feat(START_DEBIT))
461 min_runtime += sched_slice(cfs_rq, se);
463 if (!initial && sched_feat(NEW_FAIR_SLEEPERS)) {
464 latency = sysctl_sched_latency;
465 if (min_runtime > latency)
466 min_runtime -= latency;
471 se->vruntime = max(se->vruntime, min_runtime);
475 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
478 * Update the fair clock.
483 place_entity(cfs_rq, se, 0);
484 enqueue_sleeper(cfs_rq, se);
487 update_stats_enqueue(cfs_rq, se);
488 if (se != cfs_rq->curr)
489 __enqueue_entity(cfs_rq, se);
490 account_entity_enqueue(cfs_rq, se);
494 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
496 update_stats_dequeue(cfs_rq, se);
497 #ifdef CONFIG_SCHEDSTATS
499 if (entity_is_task(se)) {
500 struct task_struct *tsk = task_of(se);
502 if (tsk->state & TASK_INTERRUPTIBLE)
503 se->sleep_start = rq_of(cfs_rq)->clock;
504 if (tsk->state & TASK_UNINTERRUPTIBLE)
505 se->block_start = rq_of(cfs_rq)->clock;
509 if (se != cfs_rq->curr)
510 __dequeue_entity(cfs_rq, se);
511 account_entity_dequeue(cfs_rq, se);
515 * Preempt the current task with a newly woken task if needed:
518 check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
520 unsigned long ideal_runtime, delta_exec;
522 ideal_runtime = sched_slice(cfs_rq, curr);
523 delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
524 if (delta_exec > ideal_runtime)
525 resched_task(rq_of(cfs_rq)->curr);
529 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
531 /* 'current' is not kept within the tree. */
534 * Any task has to be enqueued before it get to execute on
535 * a CPU. So account for the time it spent waiting on the
538 update_stats_wait_end(cfs_rq, se);
539 __dequeue_entity(cfs_rq, se);
542 update_stats_curr_start(cfs_rq, se);
544 #ifdef CONFIG_SCHEDSTATS
546 * Track our maximum slice length, if the CPU's load is at
547 * least twice that of our own weight (i.e. dont track it
548 * when there are only lesser-weight tasks around):
550 if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
551 se->slice_max = max(se->slice_max,
552 se->sum_exec_runtime - se->prev_sum_exec_runtime);
555 se->prev_sum_exec_runtime = se->sum_exec_runtime;
558 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
560 struct sched_entity *se = __pick_next_entity(cfs_rq);
562 set_next_entity(cfs_rq, se);
567 static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
570 * If still on the runqueue then deactivate_task()
571 * was not called and update_curr() has to be done:
576 update_stats_curr_end(cfs_rq, prev);
579 update_stats_wait_start(cfs_rq, prev);
580 /* Put 'current' back into the tree. */
581 __enqueue_entity(cfs_rq, prev);
586 static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
589 * Update run-time statistics of the 'current'.
593 if (cfs_rq->nr_running > 1)
594 check_preempt_tick(cfs_rq, curr);
597 /**************************************************
598 * CFS operations on tasks:
601 #ifdef CONFIG_FAIR_GROUP_SCHED
603 /* Walk up scheduling entities hierarchy */
604 #define for_each_sched_entity(se) \
605 for (; se; se = se->parent)
607 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
612 /* runqueue on which this entity is (to be) queued */
613 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
618 /* runqueue "owned" by this group */
619 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
624 /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on
625 * another cpu ('this_cpu')
627 static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
629 return cfs_rq->tg->cfs_rq[this_cpu];
632 /* Iterate thr' all leaf cfs_rq's on a runqueue */
633 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
634 list_for_each_entry(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
636 /* Do the two (enqueued) tasks belong to the same group ? */
637 static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
639 if (curr->se.cfs_rq == p->se.cfs_rq)
645 #else /* CONFIG_FAIR_GROUP_SCHED */
647 #define for_each_sched_entity(se) \
648 for (; se; se = NULL)
650 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
652 return &task_rq(p)->cfs;
655 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
657 struct task_struct *p = task_of(se);
658 struct rq *rq = task_rq(p);
663 /* runqueue "owned" by this group */
664 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
669 static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
671 return &cpu_rq(this_cpu)->cfs;
674 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
675 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
677 static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
682 #endif /* CONFIG_FAIR_GROUP_SCHED */
685 * The enqueue_task method is called before nr_running is
686 * increased. Here we update the fair scheduling stats and
687 * then put the task into the rbtree:
689 static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
691 struct cfs_rq *cfs_rq;
692 struct sched_entity *se = &p->se;
694 for_each_sched_entity(se) {
697 cfs_rq = cfs_rq_of(se);
698 enqueue_entity(cfs_rq, se, wakeup);
703 * The dequeue_task method is called before nr_running is
704 * decreased. We remove the task from the rbtree and
705 * update the fair scheduling stats:
707 static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
709 struct cfs_rq *cfs_rq;
710 struct sched_entity *se = &p->se;
712 for_each_sched_entity(se) {
713 cfs_rq = cfs_rq_of(se);
714 dequeue_entity(cfs_rq, se, sleep);
715 /* Don't dequeue parent if it has other entities besides us */
716 if (cfs_rq->load.weight)
722 * sched_yield() support is very simple - we dequeue and enqueue.
724 * If compat_yield is turned on then we requeue to the end of the tree.
726 static void yield_task_fair(struct rq *rq)
728 struct cfs_rq *cfs_rq = &rq->cfs;
729 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
730 struct sched_entity *rightmost, *se = &rq->curr->se;
731 struct rb_node *parent;
734 * Are we the only task in the tree?
736 if (unlikely(cfs_rq->nr_running == 1))
739 if (likely(!sysctl_sched_compat_yield)) {
740 __update_rq_clock(rq);
742 * Dequeue and enqueue the task to update its
743 * position within the tree:
745 dequeue_entity(cfs_rq, se, 0);
746 enqueue_entity(cfs_rq, se, 0);
751 * Find the rightmost entry in the rbtree:
755 link = &parent->rb_right;
758 rightmost = rb_entry(parent, struct sched_entity, run_node);
760 * Already in the rightmost position?
762 if (unlikely(rightmost == se))
766 * Minimally necessary key value to be last in the tree:
768 se->vruntime = rightmost->vruntime + 1;
770 if (cfs_rq->rb_leftmost == &se->run_node)
771 cfs_rq->rb_leftmost = rb_next(&se->run_node);
773 * Relink the task to the rightmost position:
775 rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
776 rb_link_node(&se->run_node, parent, link);
777 rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
781 * Preempt the current task with a newly woken task if needed:
783 static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
785 struct task_struct *curr = rq->curr;
786 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
788 if (unlikely(rt_prio(p->prio))) {
794 if (is_same_group(curr, p)) {
795 s64 delta = curr->se.vruntime - p->se.vruntime;
797 if (delta > (s64)sysctl_sched_wakeup_granularity)
802 static struct task_struct *pick_next_task_fair(struct rq *rq)
804 struct cfs_rq *cfs_rq = &rq->cfs;
805 struct sched_entity *se;
807 if (unlikely(!cfs_rq->nr_running))
811 se = pick_next_entity(cfs_rq);
812 cfs_rq = group_cfs_rq(se);
819 * Account for a descheduled task:
821 static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
823 struct sched_entity *se = &prev->se;
824 struct cfs_rq *cfs_rq;
826 for_each_sched_entity(se) {
827 cfs_rq = cfs_rq_of(se);
828 put_prev_entity(cfs_rq, se);
832 /**************************************************
833 * Fair scheduling class load-balancing methods:
837 * Load-balancing iterator. Note: while the runqueue stays locked
838 * during the whole iteration, the current task might be
839 * dequeued so the iterator has to be dequeue-safe. Here we
840 * achieve that by always pre-iterating before returning
843 static inline struct task_struct *
844 __load_balance_iterator(struct cfs_rq *cfs_rq, struct rb_node *curr)
846 struct task_struct *p;
851 p = rb_entry(curr, struct task_struct, se.run_node);
852 cfs_rq->rb_load_balance_curr = rb_next(curr);
857 static struct task_struct *load_balance_start_fair(void *arg)
859 struct cfs_rq *cfs_rq = arg;
861 return __load_balance_iterator(cfs_rq, first_fair(cfs_rq));
864 static struct task_struct *load_balance_next_fair(void *arg)
866 struct cfs_rq *cfs_rq = arg;
868 return __load_balance_iterator(cfs_rq, cfs_rq->rb_load_balance_curr);
871 #ifdef CONFIG_FAIR_GROUP_SCHED
872 static int cfs_rq_best_prio(struct cfs_rq *cfs_rq)
874 struct sched_entity *curr;
875 struct task_struct *p;
877 if (!cfs_rq->nr_running)
880 curr = __pick_next_entity(cfs_rq);
888 load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
889 unsigned long max_nr_move, unsigned long max_load_move,
890 struct sched_domain *sd, enum cpu_idle_type idle,
891 int *all_pinned, int *this_best_prio)
893 struct cfs_rq *busy_cfs_rq;
894 unsigned long load_moved, total_nr_moved = 0, nr_moved;
895 long rem_load_move = max_load_move;
896 struct rq_iterator cfs_rq_iterator;
898 cfs_rq_iterator.start = load_balance_start_fair;
899 cfs_rq_iterator.next = load_balance_next_fair;
901 for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
902 #ifdef CONFIG_FAIR_GROUP_SCHED
903 struct cfs_rq *this_cfs_rq;
905 unsigned long maxload;
907 this_cfs_rq = cpu_cfs_rq(busy_cfs_rq, this_cpu);
909 imbalance = busy_cfs_rq->load.weight - this_cfs_rq->load.weight;
910 /* Don't pull if this_cfs_rq has more load than busy_cfs_rq */
914 /* Don't pull more than imbalance/2 */
916 maxload = min(rem_load_move, imbalance);
918 *this_best_prio = cfs_rq_best_prio(this_cfs_rq);
920 # define maxload rem_load_move
922 /* pass busy_cfs_rq argument into
923 * load_balance_[start|next]_fair iterators
925 cfs_rq_iterator.arg = busy_cfs_rq;
926 nr_moved = balance_tasks(this_rq, this_cpu, busiest,
927 max_nr_move, maxload, sd, idle, all_pinned,
928 &load_moved, this_best_prio, &cfs_rq_iterator);
930 total_nr_moved += nr_moved;
931 max_nr_move -= nr_moved;
932 rem_load_move -= load_moved;
934 if (max_nr_move <= 0 || rem_load_move <= 0)
938 return max_load_move - rem_load_move;
942 * scheduler tick hitting a task of our scheduling class:
944 static void task_tick_fair(struct rq *rq, struct task_struct *curr)
946 struct cfs_rq *cfs_rq;
947 struct sched_entity *se = &curr->se;
949 for_each_sched_entity(se) {
950 cfs_rq = cfs_rq_of(se);
951 entity_tick(cfs_rq, se);
955 #define swap(a,b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0)
958 * Share the fairness runtime between parent and child, thus the
959 * total amount of pressure for CPU stays equal - new tasks
960 * get a chance to run but frequent forkers are not allowed to
961 * monopolize the CPU. Note: the parent runqueue is locked,
962 * the child is not running yet.
964 static void task_new_fair(struct rq *rq, struct task_struct *p)
966 struct cfs_rq *cfs_rq = task_cfs_rq(p);
967 struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
969 sched_info_queued(p);
972 place_entity(cfs_rq, se, 1);
974 if (sysctl_sched_child_runs_first &&
975 curr->vruntime < se->vruntime) {
977 * Upon rescheduling, sched_class::put_prev_task() will place
978 * 'current' within the tree based on its new key value.
980 swap(curr->vruntime, se->vruntime);
983 update_stats_enqueue(cfs_rq, se);
984 __enqueue_entity(cfs_rq, se);
985 account_entity_enqueue(cfs_rq, se);
986 resched_task(rq->curr);
989 /* Account for a task changing its policy or group.
991 * This routine is mostly called to set cfs_rq->curr field when a task
992 * migrates between groups/classes.
994 static void set_curr_task_fair(struct rq *rq)
996 struct sched_entity *se = &rq->curr->se;
998 for_each_sched_entity(se)
999 set_next_entity(cfs_rq_of(se), se);
1003 * All the scheduling class methods:
1005 struct sched_class fair_sched_class __read_mostly = {
1006 .enqueue_task = enqueue_task_fair,
1007 .dequeue_task = dequeue_task_fair,
1008 .yield_task = yield_task_fair,
1010 .check_preempt_curr = check_preempt_wakeup,
1012 .pick_next_task = pick_next_task_fair,
1013 .put_prev_task = put_prev_task_fair,
1015 .load_balance = load_balance_fair,
1017 .set_curr_task = set_curr_task_fair,
1018 .task_tick = task_tick_fair,
1019 .task_new = task_new_fair,
1022 #ifdef CONFIG_SCHED_DEBUG
1023 static void print_cfs_stats(struct seq_file *m, int cpu)
1025 struct cfs_rq *cfs_rq;
1027 for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
1028 print_cfs_rq(m, cpu, cfs_rq);