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 const_debug unsigned int sysctl_sched_nr_latency = 20;
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 extern struct sched_class fair_sched_class;
81 /**************************************************************
82 * CFS operations on generic schedulable entities:
85 #ifdef CONFIG_FAIR_GROUP_SCHED
87 /* cpu runqueue to which this cfs_rq is attached */
88 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
93 /* An entity is a task if it doesn't "own" a runqueue */
94 #define entity_is_task(se) (!se->my_q)
96 #else /* CONFIG_FAIR_GROUP_SCHED */
98 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
100 return container_of(cfs_rq, struct rq, cfs);
103 #define entity_is_task(se) 1
105 #endif /* CONFIG_FAIR_GROUP_SCHED */
107 static inline struct task_struct *task_of(struct sched_entity *se)
109 return container_of(se, struct task_struct, se);
113 /**************************************************************
114 * Scheduling class tree data structure manipulation methods:
118 max_vruntime(u64 min_vruntime, u64 vruntime)
120 s64 delta = (s64)(vruntime - min_vruntime);
122 min_vruntime = vruntime;
128 min_vruntime(u64 min_vruntime, u64 vruntime)
130 s64 delta = (s64)(vruntime - min_vruntime);
132 min_vruntime = vruntime;
138 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
140 return se->vruntime - cfs_rq->min_vruntime;
144 * Enqueue an entity into the rb-tree:
147 __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
149 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
150 struct rb_node *parent = NULL;
151 struct sched_entity *entry;
152 s64 key = entity_key(cfs_rq, se);
156 * Find the right place in the rbtree:
160 entry = rb_entry(parent, struct sched_entity, run_node);
162 * We dont care about collisions. Nodes with
163 * the same key stay together.
165 if (key < entity_key(cfs_rq, entry)) {
166 link = &parent->rb_left;
168 link = &parent->rb_right;
174 * Maintain a cache of leftmost tree entries (it is frequently
178 cfs_rq->rb_leftmost = &se->run_node;
180 rb_link_node(&se->run_node, parent, link);
181 rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
185 __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
187 if (cfs_rq->rb_leftmost == &se->run_node)
188 cfs_rq->rb_leftmost = rb_next(&se->run_node);
190 rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
193 static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq)
195 return cfs_rq->rb_leftmost;
198 static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
200 return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node);
203 static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
205 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
206 struct sched_entity *se = NULL;
207 struct rb_node *parent;
211 se = rb_entry(parent, struct sched_entity, run_node);
212 link = &parent->rb_right;
218 /**************************************************************
219 * Scheduling class statistics methods:
222 static u64 __sched_period(unsigned long nr_running)
224 u64 period = sysctl_sched_latency;
225 unsigned long nr_latency = sysctl_sched_nr_latency;
227 if (unlikely(nr_running > nr_latency)) {
228 period *= nr_running;
229 do_div(period, nr_latency);
235 static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
237 u64 period = __sched_period(cfs_rq->nr_running);
239 period *= se->load.weight;
240 do_div(period, cfs_rq->load.weight);
245 static u64 __sched_vslice(unsigned long nr_running)
247 unsigned long period = sysctl_sched_latency;
248 unsigned long nr_latency = sysctl_sched_nr_latency;
250 if (unlikely(nr_running > nr_latency))
251 nr_running = nr_latency;
253 period /= nr_running;
259 * Update the current task's runtime statistics. Skip current tasks that
260 * are not in our scheduling class.
263 __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
264 unsigned long delta_exec)
266 unsigned long delta_exec_weighted;
269 schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
271 curr->sum_exec_runtime += delta_exec;
272 schedstat_add(cfs_rq, exec_clock, delta_exec);
273 delta_exec_weighted = delta_exec;
274 if (unlikely(curr->load.weight != NICE_0_LOAD)) {
275 delta_exec_weighted = calc_delta_fair(delta_exec_weighted,
278 curr->vruntime += delta_exec_weighted;
281 * maintain cfs_rq->min_vruntime to be a monotonic increasing
282 * value tracking the leftmost vruntime in the tree.
284 if (first_fair(cfs_rq)) {
285 vruntime = min_vruntime(curr->vruntime,
286 __pick_next_entity(cfs_rq)->vruntime);
288 vruntime = curr->vruntime;
290 cfs_rq->min_vruntime =
291 max_vruntime(cfs_rq->min_vruntime, vruntime);
294 static void update_curr(struct cfs_rq *cfs_rq)
296 struct sched_entity *curr = cfs_rq->curr;
297 u64 now = rq_of(cfs_rq)->clock;
298 unsigned long delta_exec;
304 * Get the amount of time the current task was running
305 * since the last time we changed load (this cannot
306 * overflow on 32 bits):
308 delta_exec = (unsigned long)(now - curr->exec_start);
310 __update_curr(cfs_rq, curr, delta_exec);
311 curr->exec_start = now;
315 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
317 schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
320 static inline unsigned long
321 calc_weighted(unsigned long delta, struct sched_entity *se)
323 unsigned long weight = se->load.weight;
325 if (unlikely(weight != NICE_0_LOAD))
326 return (u64)delta * se->load.weight >> NICE_0_SHIFT;
332 * Task is being enqueued - update stats:
334 static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
337 * Are we enqueueing a waiting task? (for current tasks
338 * a dequeue/enqueue event is a NOP)
340 if (se != cfs_rq->curr)
341 update_stats_wait_start(cfs_rq, se);
345 update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
347 schedstat_set(se->wait_max, max(se->wait_max,
348 rq_of(cfs_rq)->clock - se->wait_start));
349 schedstat_set(se->wait_start, 0);
353 update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
357 * Mark the end of the wait period if dequeueing a
360 if (se != cfs_rq->curr)
361 update_stats_wait_end(cfs_rq, se);
365 * We are picking a new current task - update its stats:
368 update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
371 * We are starting a new run period:
373 se->exec_start = rq_of(cfs_rq)->clock;
377 * We are descheduling a task - update its stats:
380 update_stats_curr_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
385 /**************************************************
386 * Scheduling class queueing methods:
390 account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
392 update_load_add(&cfs_rq->load, se->load.weight);
393 cfs_rq->nr_running++;
398 account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
400 update_load_sub(&cfs_rq->load, se->load.weight);
401 cfs_rq->nr_running--;
405 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
407 #ifdef CONFIG_SCHEDSTATS
408 if (se->sleep_start) {
409 u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
414 if (unlikely(delta > se->sleep_max))
415 se->sleep_max = delta;
418 se->sum_sleep_runtime += delta;
420 if (se->block_start) {
421 u64 delta = rq_of(cfs_rq)->clock - se->block_start;
426 if (unlikely(delta > se->block_max))
427 se->block_max = delta;
430 se->sum_sleep_runtime += delta;
433 * Blocking time is in units of nanosecs, so shift by 20 to
434 * get a milliseconds-range estimation of the amount of
435 * time that the task spent sleeping:
437 if (unlikely(prof_on == SLEEP_PROFILING)) {
438 struct task_struct *tsk = task_of(se);
440 profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
447 static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
449 #ifdef CONFIG_SCHED_DEBUG
450 s64 d = se->vruntime - cfs_rq->min_vruntime;
455 if (d > 3*sysctl_sched_latency)
456 schedstat_inc(cfs_rq, nr_spread_over);
461 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
465 vruntime = cfs_rq->min_vruntime;
467 if (sched_feat(USE_TREE_AVG)) {
468 struct sched_entity *last = __pick_last_entity(cfs_rq);
470 vruntime += last->vruntime;
473 } else if (sched_feat(APPROX_AVG) && cfs_rq->nr_running)
474 vruntime += __sched_vslice(cfs_rq->nr_running)/2;
476 if (initial && sched_feat(START_DEBIT))
477 vruntime += __sched_vslice(cfs_rq->nr_running + 1);
480 if (sched_feat(NEW_FAIR_SLEEPERS))
481 vruntime -= sysctl_sched_latency;
483 vruntime = max_t(s64, vruntime, se->vruntime);
486 se->vruntime = vruntime;
491 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
494 * Update the fair clock.
499 place_entity(cfs_rq, se, 0);
500 enqueue_sleeper(cfs_rq, se);
503 update_stats_enqueue(cfs_rq, se);
504 check_spread(cfs_rq, se);
505 if (se != cfs_rq->curr)
506 __enqueue_entity(cfs_rq, se);
507 account_entity_enqueue(cfs_rq, se);
511 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
513 update_stats_dequeue(cfs_rq, se);
515 #ifdef CONFIG_SCHEDSTATS
516 if (entity_is_task(se)) {
517 struct task_struct *tsk = task_of(se);
519 if (tsk->state & TASK_INTERRUPTIBLE)
520 se->sleep_start = rq_of(cfs_rq)->clock;
521 if (tsk->state & TASK_UNINTERRUPTIBLE)
522 se->block_start = rq_of(cfs_rq)->clock;
527 if (se != cfs_rq->curr)
528 __dequeue_entity(cfs_rq, se);
529 account_entity_dequeue(cfs_rq, se);
533 * Preempt the current task with a newly woken task if needed:
536 check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
538 unsigned long ideal_runtime, delta_exec;
540 ideal_runtime = sched_slice(cfs_rq, curr);
541 delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
542 if (delta_exec > ideal_runtime)
543 resched_task(rq_of(cfs_rq)->curr);
547 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
549 /* 'current' is not kept within the tree. */
552 * Any task has to be enqueued before it get to execute on
553 * a CPU. So account for the time it spent waiting on the
556 update_stats_wait_end(cfs_rq, se);
557 __dequeue_entity(cfs_rq, se);
560 update_stats_curr_start(cfs_rq, se);
562 #ifdef CONFIG_SCHEDSTATS
564 * Track our maximum slice length, if the CPU's load is at
565 * least twice that of our own weight (i.e. dont track it
566 * when there are only lesser-weight tasks around):
568 if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
569 se->slice_max = max(se->slice_max,
570 se->sum_exec_runtime - se->prev_sum_exec_runtime);
573 se->prev_sum_exec_runtime = se->sum_exec_runtime;
576 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
578 struct sched_entity *se = __pick_next_entity(cfs_rq);
580 set_next_entity(cfs_rq, se);
585 static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
588 * If still on the runqueue then deactivate_task()
589 * was not called and update_curr() has to be done:
594 update_stats_curr_end(cfs_rq, prev);
596 check_spread(cfs_rq, prev);
598 update_stats_wait_start(cfs_rq, prev);
599 /* Put 'current' back into the tree. */
600 __enqueue_entity(cfs_rq, prev);
605 static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
608 * Update run-time statistics of the 'current'.
612 if (cfs_rq->nr_running > 1)
613 check_preempt_tick(cfs_rq, curr);
616 /**************************************************
617 * CFS operations on tasks:
620 #ifdef CONFIG_FAIR_GROUP_SCHED
622 /* Walk up scheduling entities hierarchy */
623 #define for_each_sched_entity(se) \
624 for (; se; se = se->parent)
626 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
631 /* runqueue on which this entity is (to be) queued */
632 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
637 /* runqueue "owned" by this group */
638 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
643 /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on
644 * another cpu ('this_cpu')
646 static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
648 return cfs_rq->tg->cfs_rq[this_cpu];
651 /* Iterate thr' all leaf cfs_rq's on a runqueue */
652 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
653 list_for_each_entry(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
655 /* Do the two (enqueued) tasks belong to the same group ? */
656 static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
658 if (curr->se.cfs_rq == p->se.cfs_rq)
664 #else /* CONFIG_FAIR_GROUP_SCHED */
666 #define for_each_sched_entity(se) \
667 for (; se; se = NULL)
669 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
671 return &task_rq(p)->cfs;
674 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
676 struct task_struct *p = task_of(se);
677 struct rq *rq = task_rq(p);
682 /* runqueue "owned" by this group */
683 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
688 static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
690 return &cpu_rq(this_cpu)->cfs;
693 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
694 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
696 static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
701 #endif /* CONFIG_FAIR_GROUP_SCHED */
704 * The enqueue_task method is called before nr_running is
705 * increased. Here we update the fair scheduling stats and
706 * then put the task into the rbtree:
708 static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
710 struct cfs_rq *cfs_rq;
711 struct sched_entity *se = &p->se;
713 for_each_sched_entity(se) {
716 cfs_rq = cfs_rq_of(se);
717 enqueue_entity(cfs_rq, se, wakeup);
722 * The dequeue_task method is called before nr_running is
723 * decreased. We remove the task from the rbtree and
724 * update the fair scheduling stats:
726 static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
728 struct cfs_rq *cfs_rq;
729 struct sched_entity *se = &p->se;
731 for_each_sched_entity(se) {
732 cfs_rq = cfs_rq_of(se);
733 dequeue_entity(cfs_rq, se, sleep);
734 /* Don't dequeue parent if it has other entities besides us */
735 if (cfs_rq->load.weight)
741 * sched_yield() support is very simple - we dequeue and enqueue.
743 * If compat_yield is turned on then we requeue to the end of the tree.
745 static void yield_task_fair(struct rq *rq)
747 struct cfs_rq *cfs_rq = task_cfs_rq(rq->curr);
748 struct sched_entity *rightmost, *se = &rq->curr->se;
751 * Are we the only task in the tree?
753 if (unlikely(cfs_rq->nr_running == 1))
756 if (likely(!sysctl_sched_compat_yield)) {
757 __update_rq_clock(rq);
759 * Dequeue and enqueue the task to update its
760 * position within the tree:
767 * Find the rightmost entry in the rbtree:
769 rightmost = __pick_last_entity(cfs_rq);
771 * Already in the rightmost position?
773 if (unlikely(rightmost->vruntime < se->vruntime))
777 * Minimally necessary key value to be last in the tree:
778 * Upon rescheduling, sched_class::put_prev_task() will place
779 * 'current' within the tree based on its new key value.
781 se->vruntime = rightmost->vruntime + 1;
785 * Preempt the current task with a newly woken task if needed:
787 static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
789 struct task_struct *curr = rq->curr;
790 struct cfs_rq *cfs_rq = task_cfs_rq(curr), *pcfs_rq;
791 struct sched_entity *se = &curr->se, *pse = &p->se;
793 if (unlikely(rt_prio(p->prio))) {
800 for_each_sched_entity(se) {
801 cfs_rq = cfs_rq_of(se);
802 pcfs_rq = cfs_rq_of(pse);
804 if (cfs_rq == pcfs_rq) {
805 s64 delta = se->vruntime - pse->vruntime;
807 if (delta > (s64)sysctl_sched_wakeup_granularity)
811 #ifdef CONFIG_FAIR_GROUP_SCHED
817 static struct task_struct *pick_next_task_fair(struct rq *rq)
819 struct cfs_rq *cfs_rq = &rq->cfs;
820 struct sched_entity *se;
822 if (unlikely(!cfs_rq->nr_running))
826 se = pick_next_entity(cfs_rq);
827 cfs_rq = group_cfs_rq(se);
834 * Account for a descheduled task:
836 static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
838 struct sched_entity *se = &prev->se;
839 struct cfs_rq *cfs_rq;
841 for_each_sched_entity(se) {
842 cfs_rq = cfs_rq_of(se);
843 put_prev_entity(cfs_rq, se);
847 /**************************************************
848 * Fair scheduling class load-balancing methods:
852 * Load-balancing iterator. Note: while the runqueue stays locked
853 * during the whole iteration, the current task might be
854 * dequeued so the iterator has to be dequeue-safe. Here we
855 * achieve that by always pre-iterating before returning
858 static inline struct task_struct *
859 __load_balance_iterator(struct cfs_rq *cfs_rq, struct rb_node *curr)
861 struct task_struct *p;
866 p = rb_entry(curr, struct task_struct, se.run_node);
867 cfs_rq->rb_load_balance_curr = rb_next(curr);
872 static struct task_struct *load_balance_start_fair(void *arg)
874 struct cfs_rq *cfs_rq = arg;
876 return __load_balance_iterator(cfs_rq, first_fair(cfs_rq));
879 static struct task_struct *load_balance_next_fair(void *arg)
881 struct cfs_rq *cfs_rq = arg;
883 return __load_balance_iterator(cfs_rq, cfs_rq->rb_load_balance_curr);
886 #ifdef CONFIG_FAIR_GROUP_SCHED
887 static int cfs_rq_best_prio(struct cfs_rq *cfs_rq)
889 struct sched_entity *curr;
890 struct task_struct *p;
892 if (!cfs_rq->nr_running)
897 curr = __pick_next_entity(cfs_rq);
906 load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
907 unsigned long max_nr_move, unsigned long max_load_move,
908 struct sched_domain *sd, enum cpu_idle_type idle,
909 int *all_pinned, int *this_best_prio)
911 struct cfs_rq *busy_cfs_rq;
912 unsigned long load_moved, total_nr_moved = 0, nr_moved;
913 long rem_load_move = max_load_move;
914 struct rq_iterator cfs_rq_iterator;
916 cfs_rq_iterator.start = load_balance_start_fair;
917 cfs_rq_iterator.next = load_balance_next_fair;
919 for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
920 #ifdef CONFIG_FAIR_GROUP_SCHED
921 struct cfs_rq *this_cfs_rq;
923 unsigned long maxload;
925 this_cfs_rq = cpu_cfs_rq(busy_cfs_rq, this_cpu);
927 imbalance = busy_cfs_rq->load.weight - this_cfs_rq->load.weight;
928 /* Don't pull if this_cfs_rq has more load than busy_cfs_rq */
932 /* Don't pull more than imbalance/2 */
934 maxload = min(rem_load_move, imbalance);
936 *this_best_prio = cfs_rq_best_prio(this_cfs_rq);
938 # define maxload rem_load_move
940 /* pass busy_cfs_rq argument into
941 * load_balance_[start|next]_fair iterators
943 cfs_rq_iterator.arg = busy_cfs_rq;
944 nr_moved = balance_tasks(this_rq, this_cpu, busiest,
945 max_nr_move, maxload, sd, idle, all_pinned,
946 &load_moved, this_best_prio, &cfs_rq_iterator);
948 total_nr_moved += nr_moved;
949 max_nr_move -= nr_moved;
950 rem_load_move -= load_moved;
952 if (max_nr_move <= 0 || rem_load_move <= 0)
956 return max_load_move - rem_load_move;
960 * scheduler tick hitting a task of our scheduling class:
962 static void task_tick_fair(struct rq *rq, struct task_struct *curr)
964 struct cfs_rq *cfs_rq;
965 struct sched_entity *se = &curr->se;
967 for_each_sched_entity(se) {
968 cfs_rq = cfs_rq_of(se);
969 entity_tick(cfs_rq, se);
973 #define swap(a,b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0)
976 * Share the fairness runtime between parent and child, thus the
977 * total amount of pressure for CPU stays equal - new tasks
978 * get a chance to run but frequent forkers are not allowed to
979 * monopolize the CPU. Note: the parent runqueue is locked,
980 * the child is not running yet.
982 static void task_new_fair(struct rq *rq, struct task_struct *p)
984 struct cfs_rq *cfs_rq = task_cfs_rq(p);
985 struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
987 sched_info_queued(p);
990 place_entity(cfs_rq, se, 1);
992 if (sysctl_sched_child_runs_first &&
993 curr->vruntime < se->vruntime) {
995 * Upon rescheduling, sched_class::put_prev_task() will place
996 * 'current' within the tree based on its new key value.
998 swap(curr->vruntime, se->vruntime);
1001 update_stats_enqueue(cfs_rq, se);
1002 check_spread(cfs_rq, se);
1003 check_spread(cfs_rq, curr);
1004 __enqueue_entity(cfs_rq, se);
1005 account_entity_enqueue(cfs_rq, se);
1006 resched_task(rq->curr);
1009 /* Account for a task changing its policy or group.
1011 * This routine is mostly called to set cfs_rq->curr field when a task
1012 * migrates between groups/classes.
1014 static void set_curr_task_fair(struct rq *rq)
1016 struct sched_entity *se = &rq->curr->se;
1018 for_each_sched_entity(se)
1019 set_next_entity(cfs_rq_of(se), se);
1023 * All the scheduling class methods:
1025 struct sched_class fair_sched_class __read_mostly = {
1026 .enqueue_task = enqueue_task_fair,
1027 .dequeue_task = dequeue_task_fair,
1028 .yield_task = yield_task_fair,
1030 .check_preempt_curr = check_preempt_wakeup,
1032 .pick_next_task = pick_next_task_fair,
1033 .put_prev_task = put_prev_task_fair,
1035 .load_balance = load_balance_fair,
1037 .set_curr_task = set_curr_task_fair,
1038 .task_tick = task_tick_fair,
1039 .task_new = task_new_fair,
1042 #ifdef CONFIG_SCHED_DEBUG
1043 static void print_cfs_stats(struct seq_file *m, int cpu)
1045 struct cfs_rq *cfs_rq;
1047 #ifdef CONFIG_FAIR_GROUP_SCHED
1048 print_cfs_rq(m, cpu, &cpu_rq(cpu)->cfs);
1050 for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
1051 print_cfs_rq(m, cpu, cfs_rq);