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>
23 #include <linux/latencytop.h>
26 * Targeted preemption latency for CPU-bound tasks:
27 * (default: 20ms * (1 + ilog(ncpus)), units: nanoseconds)
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.
34 * (to see the precise effective timeslice length of your workload,
35 * run vmstat and monitor the context-switches (cs) field)
37 unsigned int sysctl_sched_latency
= 20000000ULL;
40 * Minimal preemption granularity for CPU-bound tasks:
41 * (default: 4 msec * (1 + ilog(ncpus)), units: nanoseconds)
43 unsigned int sysctl_sched_min_granularity
= 4000000ULL;
46 * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
48 static unsigned int sched_nr_latency
= 5;
51 * After fork, child runs first. (default) If set to 0 then
52 * parent will (try to) run first.
54 const_debug
unsigned int sysctl_sched_child_runs_first
= 1;
57 * sys_sched_yield() compat mode
59 * This option switches the agressive yield implementation of the
60 * old scheduler back on.
62 unsigned int __read_mostly sysctl_sched_compat_yield
;
65 * SCHED_OTHER wake-up granularity.
66 * (default: 5 msec * (1 + ilog(ncpus)), units: nanoseconds)
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.
72 unsigned int sysctl_sched_wakeup_granularity
= 5000000UL;
74 const_debug
unsigned int sysctl_sched_migration_cost
= 500000UL;
76 static const struct sched_class fair_sched_class
;
78 /**************************************************************
79 * CFS operations on generic schedulable entities:
82 static inline struct task_struct
*task_of(struct sched_entity
*se
)
84 return container_of(se
, struct task_struct
, se
);
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 /* Walk up scheduling entities hierarchy */
99 #define for_each_sched_entity(se) \
100 for (; se; se = se->parent)
102 static inline struct cfs_rq
*task_cfs_rq(struct task_struct
*p
)
107 /* runqueue on which this entity is (to be) queued */
108 static inline struct cfs_rq
*cfs_rq_of(struct sched_entity
*se
)
113 /* runqueue "owned" by this group */
114 static inline struct cfs_rq
*group_cfs_rq(struct sched_entity
*grp
)
119 /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on
120 * another cpu ('this_cpu')
122 static inline struct cfs_rq
*cpu_cfs_rq(struct cfs_rq
*cfs_rq
, int this_cpu
)
124 return cfs_rq
->tg
->cfs_rq
[this_cpu
];
127 /* Iterate thr' all leaf cfs_rq's on a runqueue */
128 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
129 list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
131 /* Do the two (enqueued) entities belong to the same group ? */
133 is_same_group(struct sched_entity
*se
, struct sched_entity
*pse
)
135 if (se
->cfs_rq
== pse
->cfs_rq
)
141 static inline struct sched_entity
*parent_entity(struct sched_entity
*se
)
146 /* return depth at which a sched entity is present in the hierarchy */
147 static inline int depth_se(struct sched_entity
*se
)
151 for_each_sched_entity(se
)
158 find_matching_se(struct sched_entity
**se
, struct sched_entity
**pse
)
160 int se_depth
, pse_depth
;
163 * preemption test can be made between sibling entities who are in the
164 * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
165 * both tasks until we find their ancestors who are siblings of common
169 /* First walk up until both entities are at same depth */
170 se_depth
= depth_se(*se
);
171 pse_depth
= depth_se(*pse
);
173 while (se_depth
> pse_depth
) {
175 *se
= parent_entity(*se
);
178 while (pse_depth
> se_depth
) {
180 *pse
= parent_entity(*pse
);
183 while (!is_same_group(*se
, *pse
)) {
184 *se
= parent_entity(*se
);
185 *pse
= parent_entity(*pse
);
189 #else /* CONFIG_FAIR_GROUP_SCHED */
191 static inline struct rq
*rq_of(struct cfs_rq
*cfs_rq
)
193 return container_of(cfs_rq
, struct rq
, cfs
);
196 #define entity_is_task(se) 1
198 #define for_each_sched_entity(se) \
199 for (; se; se = NULL)
201 static inline struct cfs_rq
*task_cfs_rq(struct task_struct
*p
)
203 return &task_rq(p
)->cfs
;
206 static inline struct cfs_rq
*cfs_rq_of(struct sched_entity
*se
)
208 struct task_struct
*p
= task_of(se
);
209 struct rq
*rq
= task_rq(p
);
214 /* runqueue "owned" by this group */
215 static inline struct cfs_rq
*group_cfs_rq(struct sched_entity
*grp
)
220 static inline struct cfs_rq
*cpu_cfs_rq(struct cfs_rq
*cfs_rq
, int this_cpu
)
222 return &cpu_rq(this_cpu
)->cfs
;
225 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
226 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
229 is_same_group(struct sched_entity
*se
, struct sched_entity
*pse
)
234 static inline struct sched_entity
*parent_entity(struct sched_entity
*se
)
240 find_matching_se(struct sched_entity
**se
, struct sched_entity
**pse
)
244 #endif /* CONFIG_FAIR_GROUP_SCHED */
247 /**************************************************************
248 * Scheduling class tree data structure manipulation methods:
251 static inline u64
max_vruntime(u64 min_vruntime
, u64 vruntime
)
253 s64 delta
= (s64
)(vruntime
- min_vruntime
);
255 min_vruntime
= vruntime
;
260 static inline u64
min_vruntime(u64 min_vruntime
, u64 vruntime
)
262 s64 delta
= (s64
)(vruntime
- min_vruntime
);
264 min_vruntime
= vruntime
;
269 static inline s64
entity_key(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
271 return se
->vruntime
- cfs_rq
->min_vruntime
;
274 static void update_min_vruntime(struct cfs_rq
*cfs_rq
)
276 u64 vruntime
= cfs_rq
->min_vruntime
;
279 vruntime
= cfs_rq
->curr
->vruntime
;
281 if (cfs_rq
->rb_leftmost
) {
282 struct sched_entity
*se
= rb_entry(cfs_rq
->rb_leftmost
,
287 vruntime
= se
->vruntime
;
289 vruntime
= min_vruntime(vruntime
, se
->vruntime
);
292 cfs_rq
->min_vruntime
= max_vruntime(cfs_rq
->min_vruntime
, vruntime
);
296 * Enqueue an entity into the rb-tree:
298 static void __enqueue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
300 struct rb_node
**link
= &cfs_rq
->tasks_timeline
.rb_node
;
301 struct rb_node
*parent
= NULL
;
302 struct sched_entity
*entry
;
303 s64 key
= entity_key(cfs_rq
, se
);
307 * Find the right place in the rbtree:
311 entry
= rb_entry(parent
, struct sched_entity
, run_node
);
313 * We dont care about collisions. Nodes with
314 * the same key stay together.
316 if (key
< entity_key(cfs_rq
, entry
)) {
317 link
= &parent
->rb_left
;
319 link
= &parent
->rb_right
;
325 * Maintain a cache of leftmost tree entries (it is frequently
329 cfs_rq
->rb_leftmost
= &se
->run_node
;
331 rb_link_node(&se
->run_node
, parent
, link
);
332 rb_insert_color(&se
->run_node
, &cfs_rq
->tasks_timeline
);
335 static void __dequeue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
337 if (cfs_rq
->rb_leftmost
== &se
->run_node
) {
338 struct rb_node
*next_node
;
340 next_node
= rb_next(&se
->run_node
);
341 cfs_rq
->rb_leftmost
= next_node
;
344 rb_erase(&se
->run_node
, &cfs_rq
->tasks_timeline
);
347 static struct sched_entity
*__pick_next_entity(struct cfs_rq
*cfs_rq
)
349 struct rb_node
*left
= cfs_rq
->rb_leftmost
;
354 return rb_entry(left
, struct sched_entity
, run_node
);
357 static struct sched_entity
*__pick_last_entity(struct cfs_rq
*cfs_rq
)
359 struct rb_node
*last
= rb_last(&cfs_rq
->tasks_timeline
);
364 return rb_entry(last
, struct sched_entity
, run_node
);
367 /**************************************************************
368 * Scheduling class statistics methods:
371 #ifdef CONFIG_SCHED_DEBUG
372 int sched_nr_latency_handler(struct ctl_table
*table
, int write
,
373 struct file
*filp
, void __user
*buffer
, size_t *lenp
,
376 int ret
= proc_dointvec_minmax(table
, write
, filp
, buffer
, lenp
, ppos
);
381 sched_nr_latency
= DIV_ROUND_UP(sysctl_sched_latency
,
382 sysctl_sched_min_granularity
);
391 static inline unsigned long
392 calc_delta_fair(unsigned long delta
, struct sched_entity
*se
)
394 if (unlikely(se
->load
.weight
!= NICE_0_LOAD
))
395 delta
= calc_delta_mine(delta
, NICE_0_LOAD
, &se
->load
);
401 * The idea is to set a period in which each task runs once.
403 * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
404 * this period because otherwise the slices get too small.
406 * p = (nr <= nl) ? l : l*nr/nl
408 static u64
__sched_period(unsigned long nr_running
)
410 u64 period
= sysctl_sched_latency
;
411 unsigned long nr_latency
= sched_nr_latency
;
413 if (unlikely(nr_running
> nr_latency
)) {
414 period
= sysctl_sched_min_granularity
;
415 period
*= nr_running
;
422 * We calculate the wall-time slice from the period by taking a part
423 * proportional to the weight.
427 static u64
sched_slice(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
429 u64 slice
= __sched_period(cfs_rq
->nr_running
+ !se
->on_rq
);
431 for_each_sched_entity(se
) {
432 struct load_weight
*load
;
434 cfs_rq
= cfs_rq_of(se
);
435 load
= &cfs_rq
->load
;
437 if (unlikely(!se
->on_rq
)) {
438 struct load_weight lw
= cfs_rq
->load
;
440 update_load_add(&lw
, se
->load
.weight
);
443 slice
= calc_delta_mine(slice
, se
->load
.weight
, load
);
449 * We calculate the vruntime slice of a to be inserted task
453 static u64
sched_vslice(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
455 return calc_delta_fair(sched_slice(cfs_rq
, se
), se
);
459 * Update the current task's runtime statistics. Skip current tasks that
460 * are not in our scheduling class.
463 __update_curr(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
,
464 unsigned long delta_exec
)
466 unsigned long delta_exec_weighted
;
468 schedstat_set(curr
->exec_max
, max((u64
)delta_exec
, curr
->exec_max
));
470 curr
->sum_exec_runtime
+= delta_exec
;
471 schedstat_add(cfs_rq
, exec_clock
, delta_exec
);
472 delta_exec_weighted
= calc_delta_fair(delta_exec
, curr
);
473 curr
->vruntime
+= delta_exec_weighted
;
474 update_min_vruntime(cfs_rq
);
477 static void update_curr(struct cfs_rq
*cfs_rq
)
479 struct sched_entity
*curr
= cfs_rq
->curr
;
480 u64 now
= rq_of(cfs_rq
)->clock
;
481 unsigned long delta_exec
;
487 * Get the amount of time the current task was running
488 * since the last time we changed load (this cannot
489 * overflow on 32 bits):
491 delta_exec
= (unsigned long)(now
- curr
->exec_start
);
495 __update_curr(cfs_rq
, curr
, delta_exec
);
496 curr
->exec_start
= now
;
498 if (entity_is_task(curr
)) {
499 struct task_struct
*curtask
= task_of(curr
);
501 cpuacct_charge(curtask
, delta_exec
);
502 account_group_exec_runtime(curtask
, delta_exec
);
507 update_stats_wait_start(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
509 schedstat_set(se
->wait_start
, rq_of(cfs_rq
)->clock
);
513 * Task is being enqueued - update stats:
515 static void update_stats_enqueue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
518 * Are we enqueueing a waiting task? (for current tasks
519 * a dequeue/enqueue event is a NOP)
521 if (se
!= cfs_rq
->curr
)
522 update_stats_wait_start(cfs_rq
, se
);
526 update_stats_wait_end(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
528 schedstat_set(se
->wait_max
, max(se
->wait_max
,
529 rq_of(cfs_rq
)->clock
- se
->wait_start
));
530 schedstat_set(se
->wait_count
, se
->wait_count
+ 1);
531 schedstat_set(se
->wait_sum
, se
->wait_sum
+
532 rq_of(cfs_rq
)->clock
- se
->wait_start
);
533 schedstat_set(se
->wait_start
, 0);
537 update_stats_dequeue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
540 * Mark the end of the wait period if dequeueing a
543 if (se
!= cfs_rq
->curr
)
544 update_stats_wait_end(cfs_rq
, se
);
548 * We are picking a new current task - update its stats:
551 update_stats_curr_start(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
554 * We are starting a new run period:
556 se
->exec_start
= rq_of(cfs_rq
)->clock
;
559 /**************************************************
560 * Scheduling class queueing methods:
563 #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
565 add_cfs_task_weight(struct cfs_rq
*cfs_rq
, unsigned long weight
)
567 cfs_rq
->task_weight
+= weight
;
571 add_cfs_task_weight(struct cfs_rq
*cfs_rq
, unsigned long weight
)
577 account_entity_enqueue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
579 update_load_add(&cfs_rq
->load
, se
->load
.weight
);
580 if (!parent_entity(se
))
581 inc_cpu_load(rq_of(cfs_rq
), se
->load
.weight
);
582 if (entity_is_task(se
)) {
583 add_cfs_task_weight(cfs_rq
, se
->load
.weight
);
584 list_add(&se
->group_node
, &cfs_rq
->tasks
);
586 cfs_rq
->nr_running
++;
591 account_entity_dequeue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
593 update_load_sub(&cfs_rq
->load
, se
->load
.weight
);
594 if (!parent_entity(se
))
595 dec_cpu_load(rq_of(cfs_rq
), se
->load
.weight
);
596 if (entity_is_task(se
)) {
597 add_cfs_task_weight(cfs_rq
, -se
->load
.weight
);
598 list_del_init(&se
->group_node
);
600 cfs_rq
->nr_running
--;
604 static void enqueue_sleeper(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
606 #ifdef CONFIG_SCHEDSTATS
607 if (se
->sleep_start
) {
608 u64 delta
= rq_of(cfs_rq
)->clock
- se
->sleep_start
;
609 struct task_struct
*tsk
= task_of(se
);
614 if (unlikely(delta
> se
->sleep_max
))
615 se
->sleep_max
= delta
;
618 se
->sum_sleep_runtime
+= delta
;
620 account_scheduler_latency(tsk
, delta
>> 10, 1);
622 if (se
->block_start
) {
623 u64 delta
= rq_of(cfs_rq
)->clock
- se
->block_start
;
624 struct task_struct
*tsk
= task_of(se
);
629 if (unlikely(delta
> se
->block_max
))
630 se
->block_max
= delta
;
633 se
->sum_sleep_runtime
+= delta
;
636 * Blocking time is in units of nanosecs, so shift by 20 to
637 * get a milliseconds-range estimation of the amount of
638 * time that the task spent sleeping:
640 if (unlikely(prof_on
== SLEEP_PROFILING
)) {
642 profile_hits(SLEEP_PROFILING
, (void *)get_wchan(tsk
),
645 account_scheduler_latency(tsk
, delta
>> 10, 0);
650 static void check_spread(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
652 #ifdef CONFIG_SCHED_DEBUG
653 s64 d
= se
->vruntime
- cfs_rq
->min_vruntime
;
658 if (d
> 3*sysctl_sched_latency
)
659 schedstat_inc(cfs_rq
, nr_spread_over
);
664 place_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int initial
)
666 u64 vruntime
= cfs_rq
->min_vruntime
;
669 * The 'current' period is already promised to the current tasks,
670 * however the extra weight of the new task will slow them down a
671 * little, place the new task so that it fits in the slot that
672 * stays open at the end.
674 if (initial
&& sched_feat(START_DEBIT
))
675 vruntime
+= sched_vslice(cfs_rq
, se
);
678 /* sleeps upto a single latency don't count. */
679 if (sched_feat(NEW_FAIR_SLEEPERS
)) {
680 unsigned long thresh
= sysctl_sched_latency
;
683 * Convert the sleeper threshold into virtual time.
684 * SCHED_IDLE is a special sub-class. We care about
685 * fairness only relative to other SCHED_IDLE tasks,
686 * all of which have the same weight.
688 if (sched_feat(NORMALIZED_SLEEPER
) &&
689 task_of(se
)->policy
!= SCHED_IDLE
)
690 thresh
= calc_delta_fair(thresh
, se
);
695 /* ensure we never gain time by being placed backwards. */
696 vruntime
= max_vruntime(se
->vruntime
, vruntime
);
699 se
->vruntime
= vruntime
;
703 enqueue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int wakeup
)
706 * Update run-time statistics of the 'current'.
709 account_entity_enqueue(cfs_rq
, se
);
712 place_entity(cfs_rq
, se
, 0);
713 enqueue_sleeper(cfs_rq
, se
);
716 update_stats_enqueue(cfs_rq
, se
);
717 check_spread(cfs_rq
, se
);
718 if (se
!= cfs_rq
->curr
)
719 __enqueue_entity(cfs_rq
, se
);
722 static void __clear_buddies(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
724 if (cfs_rq
->last
== se
)
727 if (cfs_rq
->next
== se
)
731 static void clear_buddies(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
733 for_each_sched_entity(se
)
734 __clear_buddies(cfs_rq_of(se
), se
);
738 dequeue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int sleep
)
741 * Update run-time statistics of the 'current'.
745 update_stats_dequeue(cfs_rq
, se
);
747 #ifdef CONFIG_SCHEDSTATS
748 if (entity_is_task(se
)) {
749 struct task_struct
*tsk
= task_of(se
);
751 if (tsk
->state
& TASK_INTERRUPTIBLE
)
752 se
->sleep_start
= rq_of(cfs_rq
)->clock
;
753 if (tsk
->state
& TASK_UNINTERRUPTIBLE
)
754 se
->block_start
= rq_of(cfs_rq
)->clock
;
759 clear_buddies(cfs_rq
, se
);
761 if (se
!= cfs_rq
->curr
)
762 __dequeue_entity(cfs_rq
, se
);
763 account_entity_dequeue(cfs_rq
, se
);
764 update_min_vruntime(cfs_rq
);
768 * Preempt the current task with a newly woken task if needed:
771 check_preempt_tick(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
)
773 unsigned long ideal_runtime
, delta_exec
;
775 ideal_runtime
= sched_slice(cfs_rq
, curr
);
776 delta_exec
= curr
->sum_exec_runtime
- curr
->prev_sum_exec_runtime
;
777 if (delta_exec
> ideal_runtime
) {
778 resched_task(rq_of(cfs_rq
)->curr
);
780 * The current task ran long enough, ensure it doesn't get
781 * re-elected due to buddy favours.
783 clear_buddies(cfs_rq
, curr
);
788 set_next_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
790 /* 'current' is not kept within the tree. */
793 * Any task has to be enqueued before it get to execute on
794 * a CPU. So account for the time it spent waiting on the
797 update_stats_wait_end(cfs_rq
, se
);
798 __dequeue_entity(cfs_rq
, se
);
801 update_stats_curr_start(cfs_rq
, se
);
803 #ifdef CONFIG_SCHEDSTATS
805 * Track our maximum slice length, if the CPU's load is at
806 * least twice that of our own weight (i.e. dont track it
807 * when there are only lesser-weight tasks around):
809 if (rq_of(cfs_rq
)->load
.weight
>= 2*se
->load
.weight
) {
810 se
->slice_max
= max(se
->slice_max
,
811 se
->sum_exec_runtime
- se
->prev_sum_exec_runtime
);
814 se
->prev_sum_exec_runtime
= se
->sum_exec_runtime
;
818 wakeup_preempt_entity(struct sched_entity
*curr
, struct sched_entity
*se
);
820 static struct sched_entity
*pick_next_entity(struct cfs_rq
*cfs_rq
)
822 struct sched_entity
*se
= __pick_next_entity(cfs_rq
);
824 if (cfs_rq
->next
&& wakeup_preempt_entity(cfs_rq
->next
, se
) < 1)
827 if (cfs_rq
->last
&& wakeup_preempt_entity(cfs_rq
->last
, se
) < 1)
833 static void put_prev_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*prev
)
836 * If still on the runqueue then deactivate_task()
837 * was not called and update_curr() has to be done:
842 check_spread(cfs_rq
, prev
);
844 update_stats_wait_start(cfs_rq
, prev
);
845 /* Put 'current' back into the tree. */
846 __enqueue_entity(cfs_rq
, prev
);
852 entity_tick(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
, int queued
)
855 * Update run-time statistics of the 'current'.
859 #ifdef CONFIG_SCHED_HRTICK
861 * queued ticks are scheduled to match the slice, so don't bother
862 * validating it and just reschedule.
865 resched_task(rq_of(cfs_rq
)->curr
);
869 * don't let the period tick interfere with the hrtick preemption
871 if (!sched_feat(DOUBLE_TICK
) &&
872 hrtimer_active(&rq_of(cfs_rq
)->hrtick_timer
))
876 if (cfs_rq
->nr_running
> 1 || !sched_feat(WAKEUP_PREEMPT
))
877 check_preempt_tick(cfs_rq
, curr
);
880 /**************************************************
881 * CFS operations on tasks:
884 #ifdef CONFIG_SCHED_HRTICK
885 static void hrtick_start_fair(struct rq
*rq
, struct task_struct
*p
)
887 struct sched_entity
*se
= &p
->se
;
888 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
890 WARN_ON(task_rq(p
) != rq
);
892 if (hrtick_enabled(rq
) && cfs_rq
->nr_running
> 1) {
893 u64 slice
= sched_slice(cfs_rq
, se
);
894 u64 ran
= se
->sum_exec_runtime
- se
->prev_sum_exec_runtime
;
895 s64 delta
= slice
- ran
;
904 * Don't schedule slices shorter than 10000ns, that just
905 * doesn't make sense. Rely on vruntime for fairness.
908 delta
= max_t(s64
, 10000LL, delta
);
910 hrtick_start(rq
, delta
);
915 * called from enqueue/dequeue and updates the hrtick when the
916 * current task is from our class and nr_running is low enough
919 static void hrtick_update(struct rq
*rq
)
921 struct task_struct
*curr
= rq
->curr
;
923 if (curr
->sched_class
!= &fair_sched_class
)
926 if (cfs_rq_of(&curr
->se
)->nr_running
< sched_nr_latency
)
927 hrtick_start_fair(rq
, curr
);
929 #else /* !CONFIG_SCHED_HRTICK */
931 hrtick_start_fair(struct rq
*rq
, struct task_struct
*p
)
935 static inline void hrtick_update(struct rq
*rq
)
941 * The enqueue_task method is called before nr_running is
942 * increased. Here we update the fair scheduling stats and
943 * then put the task into the rbtree:
945 static void enqueue_task_fair(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
947 struct cfs_rq
*cfs_rq
;
948 struct sched_entity
*se
= &p
->se
;
950 for_each_sched_entity(se
) {
953 cfs_rq
= cfs_rq_of(se
);
954 enqueue_entity(cfs_rq
, se
, wakeup
);
962 * The dequeue_task method is called before nr_running is
963 * decreased. We remove the task from the rbtree and
964 * update the fair scheduling stats:
966 static void dequeue_task_fair(struct rq
*rq
, struct task_struct
*p
, int sleep
)
968 struct cfs_rq
*cfs_rq
;
969 struct sched_entity
*se
= &p
->se
;
971 for_each_sched_entity(se
) {
972 cfs_rq
= cfs_rq_of(se
);
973 dequeue_entity(cfs_rq
, se
, sleep
);
974 /* Don't dequeue parent if it has other entities besides us */
975 if (cfs_rq
->load
.weight
)
984 * sched_yield() support is very simple - we dequeue and enqueue.
986 * If compat_yield is turned on then we requeue to the end of the tree.
988 static void yield_task_fair(struct rq
*rq
)
990 struct task_struct
*curr
= rq
->curr
;
991 struct cfs_rq
*cfs_rq
= task_cfs_rq(curr
);
992 struct sched_entity
*rightmost
, *se
= &curr
->se
;
995 * Are we the only task in the tree?
997 if (unlikely(cfs_rq
->nr_running
== 1))
1000 clear_buddies(cfs_rq
, se
);
1002 if (likely(!sysctl_sched_compat_yield
) && curr
->policy
!= SCHED_BATCH
) {
1003 update_rq_clock(rq
);
1005 * Update run-time statistics of the 'current'.
1007 update_curr(cfs_rq
);
1012 * Find the rightmost entry in the rbtree:
1014 rightmost
= __pick_last_entity(cfs_rq
);
1016 * Already in the rightmost position?
1018 if (unlikely(!rightmost
|| rightmost
->vruntime
< se
->vruntime
))
1022 * Minimally necessary key value to be last in the tree:
1023 * Upon rescheduling, sched_class::put_prev_task() will place
1024 * 'current' within the tree based on its new key value.
1026 se
->vruntime
= rightmost
->vruntime
+ 1;
1030 * wake_idle() will wake a task on an idle cpu if task->cpu is
1031 * not idle and an idle cpu is available. The span of cpus to
1032 * search starts with cpus closest then further out as needed,
1033 * so we always favor a closer, idle cpu.
1034 * Domains may include CPUs that are not usable for migration,
1035 * hence we need to mask them out (cpu_active_mask)
1037 * Returns the CPU we should wake onto.
1039 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1040 static int wake_idle(int cpu
, struct task_struct
*p
)
1042 struct sched_domain
*sd
;
1044 unsigned int chosen_wakeup_cpu
;
1048 * At POWERSAVINGS_BALANCE_WAKEUP level, if both this_cpu and prev_cpu
1049 * are idle and this is not a kernel thread and this task's affinity
1050 * allows it to be moved to preferred cpu, then just move!
1053 this_cpu
= smp_processor_id();
1055 cpu_rq(this_cpu
)->rd
->sched_mc_preferred_wakeup_cpu
;
1057 if (sched_mc_power_savings
>= POWERSAVINGS_BALANCE_WAKEUP
&&
1058 idle_cpu(cpu
) && idle_cpu(this_cpu
) &&
1059 p
->mm
&& !(p
->flags
& PF_KTHREAD
) &&
1060 cpu_isset(chosen_wakeup_cpu
, p
->cpus_allowed
))
1061 return chosen_wakeup_cpu
;
1064 * If it is idle, then it is the best cpu to run this task.
1066 * This cpu is also the best, if it has more than one task already.
1067 * Siblings must be also busy(in most cases) as they didn't already
1068 * pickup the extra load from this cpu and hence we need not check
1069 * sibling runqueue info. This will avoid the checks and cache miss
1070 * penalities associated with that.
1072 if (idle_cpu(cpu
) || cpu_rq(cpu
)->cfs
.nr_running
> 1)
1075 for_each_domain(cpu
, sd
) {
1076 if ((sd
->flags
& SD_WAKE_IDLE
)
1077 || ((sd
->flags
& SD_WAKE_IDLE_FAR
)
1078 && !task_hot(p
, task_rq(p
)->clock
, sd
))) {
1079 for_each_cpu_and(i
, sched_domain_span(sd
),
1081 if (cpu_active(i
) && idle_cpu(i
)) {
1082 if (i
!= task_cpu(p
)) {
1084 se
.nr_wakeups_idle
);
1095 #else /* !ARCH_HAS_SCHED_WAKE_IDLE*/
1096 static inline int wake_idle(int cpu
, struct task_struct
*p
)
1104 #ifdef CONFIG_FAIR_GROUP_SCHED
1106 * effective_load() calculates the load change as seen from the root_task_group
1108 * Adding load to a group doesn't make a group heavier, but can cause movement
1109 * of group shares between cpus. Assuming the shares were perfectly aligned one
1110 * can calculate the shift in shares.
1112 * The problem is that perfectly aligning the shares is rather expensive, hence
1113 * we try to avoid doing that too often - see update_shares(), which ratelimits
1116 * We compensate this by not only taking the current delta into account, but
1117 * also considering the delta between when the shares were last adjusted and
1120 * We still saw a performance dip, some tracing learned us that between
1121 * cgroup:/ and cgroup:/foo balancing the number of affine wakeups increased
1122 * significantly. Therefore try to bias the error in direction of failing
1123 * the affine wakeup.
1126 static long effective_load(struct task_group
*tg
, int cpu
,
1129 struct sched_entity
*se
= tg
->se
[cpu
];
1135 * By not taking the decrease of shares on the other cpu into
1136 * account our error leans towards reducing the affine wakeups.
1138 if (!wl
&& sched_feat(ASYM_EFF_LOAD
))
1141 for_each_sched_entity(se
) {
1142 long S
, rw
, s
, a
, b
;
1146 * Instead of using this increment, also add the difference
1147 * between when the shares were last updated and now.
1149 more_w
= se
->my_q
->load
.weight
- se
->my_q
->rq_weight
;
1153 S
= se
->my_q
->tg
->shares
;
1154 s
= se
->my_q
->shares
;
1155 rw
= se
->my_q
->rq_weight
;
1166 * Assume the group is already running and will
1167 * thus already be accounted for in the weight.
1169 * That is, moving shares between CPUs, does not
1170 * alter the group weight.
1180 static inline unsigned long effective_load(struct task_group
*tg
, int cpu
,
1181 unsigned long wl
, unsigned long wg
)
1189 wake_affine(struct sched_domain
*this_sd
, struct rq
*this_rq
,
1190 struct task_struct
*p
, int prev_cpu
, int this_cpu
, int sync
,
1191 int idx
, unsigned long load
, unsigned long this_load
,
1192 unsigned int imbalance
)
1194 struct task_struct
*curr
= this_rq
->curr
;
1195 struct task_group
*tg
;
1196 unsigned long tl
= this_load
;
1197 unsigned long tl_per_task
;
1198 unsigned long weight
;
1201 if (!(this_sd
->flags
& SD_WAKE_AFFINE
) || !sched_feat(AFFINE_WAKEUPS
))
1204 if (sync
&& (curr
->se
.avg_overlap
> sysctl_sched_migration_cost
||
1205 p
->se
.avg_overlap
> sysctl_sched_migration_cost
))
1209 * If sync wakeup then subtract the (maximum possible)
1210 * effect of the currently running task from the load
1211 * of the current CPU:
1214 tg
= task_group(current
);
1215 weight
= current
->se
.load
.weight
;
1217 tl
+= effective_load(tg
, this_cpu
, -weight
, -weight
);
1218 load
+= effective_load(tg
, prev_cpu
, 0, -weight
);
1222 weight
= p
->se
.load
.weight
;
1224 balanced
= 100*(tl
+ effective_load(tg
, this_cpu
, weight
, weight
)) <=
1225 imbalance
*(load
+ effective_load(tg
, prev_cpu
, 0, weight
));
1228 * If the currently running task will sleep within
1229 * a reasonable amount of time then attract this newly
1232 if (sync
&& balanced
)
1235 schedstat_inc(p
, se
.nr_wakeups_affine_attempts
);
1236 tl_per_task
= cpu_avg_load_per_task(this_cpu
);
1238 if (balanced
|| (tl
<= load
&& tl
+ target_load(prev_cpu
, idx
) <=
1241 * This domain has SD_WAKE_AFFINE and
1242 * p is cache cold in this domain, and
1243 * there is no bad imbalance.
1245 schedstat_inc(this_sd
, ttwu_move_affine
);
1246 schedstat_inc(p
, se
.nr_wakeups_affine
);
1253 static int select_task_rq_fair(struct task_struct
*p
, int sync
)
1255 struct sched_domain
*sd
, *this_sd
= NULL
;
1256 int prev_cpu
, this_cpu
, new_cpu
;
1257 unsigned long load
, this_load
;
1259 unsigned int imbalance
;
1262 prev_cpu
= task_cpu(p
);
1263 this_cpu
= smp_processor_id();
1264 this_rq
= cpu_rq(this_cpu
);
1267 if (prev_cpu
== this_cpu
)
1270 * 'this_sd' is the first domain that both
1271 * this_cpu and prev_cpu are present in:
1273 for_each_domain(this_cpu
, sd
) {
1274 if (cpumask_test_cpu(prev_cpu
, sched_domain_span(sd
))) {
1280 if (unlikely(!cpumask_test_cpu(this_cpu
, &p
->cpus_allowed
)))
1284 * Check for affine wakeup and passive balancing possibilities.
1289 idx
= this_sd
->wake_idx
;
1291 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1293 load
= source_load(prev_cpu
, idx
);
1294 this_load
= target_load(this_cpu
, idx
);
1296 if (wake_affine(this_sd
, this_rq
, p
, prev_cpu
, this_cpu
, sync
, idx
,
1297 load
, this_load
, imbalance
))
1301 * Start passive balancing when half the imbalance_pct
1304 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1305 if (imbalance
*this_load
<= 100*load
) {
1306 schedstat_inc(this_sd
, ttwu_move_balance
);
1307 schedstat_inc(p
, se
.nr_wakeups_passive
);
1313 return wake_idle(new_cpu
, p
);
1315 #endif /* CONFIG_SMP */
1318 * Adaptive granularity
1320 * se->avg_wakeup gives the average time a task runs until it does a wakeup,
1321 * with the limit of wakeup_gran -- when it never does a wakeup.
1323 * So the smaller avg_wakeup is the faster we want this task to preempt,
1324 * but we don't want to treat the preemptee unfairly and therefore allow it
1325 * to run for at least the amount of time we'd like to run.
1327 * NOTE: we use 2*avg_wakeup to increase the probability of actually doing one
1329 * NOTE: we use *nr_running to scale with load, this nicely matches the
1330 * degrading latency on load.
1332 static unsigned long
1333 adaptive_gran(struct sched_entity
*curr
, struct sched_entity
*se
)
1335 u64 this_run
= curr
->sum_exec_runtime
- curr
->prev_sum_exec_runtime
;
1336 u64 expected_wakeup
= 2*se
->avg_wakeup
* cfs_rq_of(se
)->nr_running
;
1339 if (this_run
< expected_wakeup
)
1340 gran
= expected_wakeup
- this_run
;
1342 return min_t(s64
, gran
, sysctl_sched_wakeup_granularity
);
1345 static unsigned long
1346 wakeup_gran(struct sched_entity
*curr
, struct sched_entity
*se
)
1348 unsigned long gran
= sysctl_sched_wakeup_granularity
;
1350 if (cfs_rq_of(curr
)->curr
&& sched_feat(ADAPTIVE_GRAN
))
1351 gran
= adaptive_gran(curr
, se
);
1354 * Since its curr running now, convert the gran from real-time
1355 * to virtual-time in his units.
1357 if (sched_feat(ASYM_GRAN
)) {
1359 * By using 'se' instead of 'curr' we penalize light tasks, so
1360 * they get preempted easier. That is, if 'se' < 'curr' then
1361 * the resulting gran will be larger, therefore penalizing the
1362 * lighter, if otoh 'se' > 'curr' then the resulting gran will
1363 * be smaller, again penalizing the lighter task.
1365 * This is especially important for buddies when the leftmost
1366 * task is higher priority than the buddy.
1368 if (unlikely(se
->load
.weight
!= NICE_0_LOAD
))
1369 gran
= calc_delta_fair(gran
, se
);
1371 if (unlikely(curr
->load
.weight
!= NICE_0_LOAD
))
1372 gran
= calc_delta_fair(gran
, curr
);
1379 * Should 'se' preempt 'curr'.
1393 wakeup_preempt_entity(struct sched_entity
*curr
, struct sched_entity
*se
)
1395 s64 gran
, vdiff
= curr
->vruntime
- se
->vruntime
;
1400 gran
= wakeup_gran(curr
, se
);
1407 static void set_last_buddy(struct sched_entity
*se
)
1409 if (likely(task_of(se
)->policy
!= SCHED_IDLE
)) {
1410 for_each_sched_entity(se
)
1411 cfs_rq_of(se
)->last
= se
;
1415 static void set_next_buddy(struct sched_entity
*se
)
1417 if (likely(task_of(se
)->policy
!= SCHED_IDLE
)) {
1418 for_each_sched_entity(se
)
1419 cfs_rq_of(se
)->next
= se
;
1424 * Preempt the current task with a newly woken task if needed:
1426 static void check_preempt_wakeup(struct rq
*rq
, struct task_struct
*p
, int sync
)
1428 struct task_struct
*curr
= rq
->curr
;
1429 struct sched_entity
*se
= &curr
->se
, *pse
= &p
->se
;
1430 struct cfs_rq
*cfs_rq
= task_cfs_rq(curr
);
1432 update_curr(cfs_rq
);
1434 if (unlikely(rt_prio(p
->prio
))) {
1439 if (unlikely(p
->sched_class
!= &fair_sched_class
)){
1440 update_rq_clock(rq
);
1441 update_curr(cfs_rq
);
1447 if (unlikely(se
== pse
))
1451 * Only set the backward buddy when the current task is still on the
1452 * rq. This can happen when a wakeup gets interleaved with schedule on
1453 * the ->pre_schedule() or idle_balance() point, either of which can
1456 * Also, during early boot the idle thread is in the fair class, for
1457 * obvious reasons its a bad idea to schedule back to the idle thread.
1459 if (sched_feat(LAST_BUDDY
) && likely(se
->on_rq
&& curr
!= rq
->idle
))
1461 set_next_buddy(pse
);
1464 * We can come here with TIF_NEED_RESCHED already set from new task
1467 if (test_tsk_need_resched(curr
))
1471 * Batch and idle tasks do not preempt (their preemption is driven by
1474 if (unlikely(p
->policy
!= SCHED_NORMAL
))
1477 /* Idle tasks are by definition preempted by everybody. */
1478 if (unlikely(curr
->policy
== SCHED_IDLE
)) {
1483 if (!sched_feat(WAKEUP_PREEMPT
))
1486 if (sched_feat(WAKEUP_OVERLAP
) && (sync
||
1487 (se
->avg_overlap
< sysctl_sched_migration_cost
&&
1488 pse
->avg_overlap
< sysctl_sched_migration_cost
))) {
1493 find_matching_se(&se
, &pse
);
1498 if (wakeup_preempt_entity(se
, pse
) == 1) {
1503 se
= parent_entity(se
);
1504 pse
= parent_entity(pse
);
1508 static struct task_struct
*pick_next_task_fair(struct rq
*rq
)
1510 struct task_struct
*p
;
1511 struct cfs_rq
*cfs_rq
= &rq
->cfs
;
1512 struct sched_entity
*se
;
1514 if (unlikely(!cfs_rq
->nr_running
))
1518 se
= pick_next_entity(cfs_rq
);
1520 * If se was a buddy, clear it so that it will have to earn
1523 __clear_buddies(cfs_rq
, se
);
1524 set_next_entity(cfs_rq
, se
);
1525 cfs_rq
= group_cfs_rq(se
);
1529 hrtick_start_fair(rq
, p
);
1535 * Account for a descheduled task:
1537 static void put_prev_task_fair(struct rq
*rq
, struct task_struct
*prev
)
1539 struct sched_entity
*se
= &prev
->se
;
1540 struct cfs_rq
*cfs_rq
;
1542 for_each_sched_entity(se
) {
1543 cfs_rq
= cfs_rq_of(se
);
1544 put_prev_entity(cfs_rq
, se
);
1549 /**************************************************
1550 * Fair scheduling class load-balancing methods:
1554 * Load-balancing iterator. Note: while the runqueue stays locked
1555 * during the whole iteration, the current task might be
1556 * dequeued so the iterator has to be dequeue-safe. Here we
1557 * achieve that by always pre-iterating before returning
1560 static struct task_struct
*
1561 __load_balance_iterator(struct cfs_rq
*cfs_rq
, struct list_head
*next
)
1563 struct task_struct
*p
= NULL
;
1564 struct sched_entity
*se
;
1566 if (next
== &cfs_rq
->tasks
)
1569 se
= list_entry(next
, struct sched_entity
, group_node
);
1571 cfs_rq
->balance_iterator
= next
->next
;
1576 static struct task_struct
*load_balance_start_fair(void *arg
)
1578 struct cfs_rq
*cfs_rq
= arg
;
1580 return __load_balance_iterator(cfs_rq
, cfs_rq
->tasks
.next
);
1583 static struct task_struct
*load_balance_next_fair(void *arg
)
1585 struct cfs_rq
*cfs_rq
= arg
;
1587 return __load_balance_iterator(cfs_rq
, cfs_rq
->balance_iterator
);
1590 static unsigned long
1591 __load_balance_fair(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
1592 unsigned long max_load_move
, struct sched_domain
*sd
,
1593 enum cpu_idle_type idle
, int *all_pinned
, int *this_best_prio
,
1594 struct cfs_rq
*cfs_rq
)
1596 struct rq_iterator cfs_rq_iterator
;
1598 cfs_rq_iterator
.start
= load_balance_start_fair
;
1599 cfs_rq_iterator
.next
= load_balance_next_fair
;
1600 cfs_rq_iterator
.arg
= cfs_rq
;
1602 return balance_tasks(this_rq
, this_cpu
, busiest
,
1603 max_load_move
, sd
, idle
, all_pinned
,
1604 this_best_prio
, &cfs_rq_iterator
);
1607 #ifdef CONFIG_FAIR_GROUP_SCHED
1608 static unsigned long
1609 load_balance_fair(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
1610 unsigned long max_load_move
,
1611 struct sched_domain
*sd
, enum cpu_idle_type idle
,
1612 int *all_pinned
, int *this_best_prio
)
1614 long rem_load_move
= max_load_move
;
1615 int busiest_cpu
= cpu_of(busiest
);
1616 struct task_group
*tg
;
1619 update_h_load(busiest_cpu
);
1621 list_for_each_entry_rcu(tg
, &task_groups
, list
) {
1622 struct cfs_rq
*busiest_cfs_rq
= tg
->cfs_rq
[busiest_cpu
];
1623 unsigned long busiest_h_load
= busiest_cfs_rq
->h_load
;
1624 unsigned long busiest_weight
= busiest_cfs_rq
->load
.weight
;
1625 u64 rem_load
, moved_load
;
1630 if (!busiest_cfs_rq
->task_weight
)
1633 rem_load
= (u64
)rem_load_move
* busiest_weight
;
1634 rem_load
= div_u64(rem_load
, busiest_h_load
+ 1);
1636 moved_load
= __load_balance_fair(this_rq
, this_cpu
, busiest
,
1637 rem_load
, sd
, idle
, all_pinned
, this_best_prio
,
1638 tg
->cfs_rq
[busiest_cpu
]);
1643 moved_load
*= busiest_h_load
;
1644 moved_load
= div_u64(moved_load
, busiest_weight
+ 1);
1646 rem_load_move
-= moved_load
;
1647 if (rem_load_move
< 0)
1652 return max_load_move
- rem_load_move
;
1655 static unsigned long
1656 load_balance_fair(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
1657 unsigned long max_load_move
,
1658 struct sched_domain
*sd
, enum cpu_idle_type idle
,
1659 int *all_pinned
, int *this_best_prio
)
1661 return __load_balance_fair(this_rq
, this_cpu
, busiest
,
1662 max_load_move
, sd
, idle
, all_pinned
,
1663 this_best_prio
, &busiest
->cfs
);
1668 move_one_task_fair(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
1669 struct sched_domain
*sd
, enum cpu_idle_type idle
)
1671 struct cfs_rq
*busy_cfs_rq
;
1672 struct rq_iterator cfs_rq_iterator
;
1674 cfs_rq_iterator
.start
= load_balance_start_fair
;
1675 cfs_rq_iterator
.next
= load_balance_next_fair
;
1677 for_each_leaf_cfs_rq(busiest
, busy_cfs_rq
) {
1679 * pass busy_cfs_rq argument into
1680 * load_balance_[start|next]_fair iterators
1682 cfs_rq_iterator
.arg
= busy_cfs_rq
;
1683 if (iter_move_one_task(this_rq
, this_cpu
, busiest
, sd
, idle
,
1690 #endif /* CONFIG_SMP */
1693 * scheduler tick hitting a task of our scheduling class:
1695 static void task_tick_fair(struct rq
*rq
, struct task_struct
*curr
, int queued
)
1697 struct cfs_rq
*cfs_rq
;
1698 struct sched_entity
*se
= &curr
->se
;
1700 for_each_sched_entity(se
) {
1701 cfs_rq
= cfs_rq_of(se
);
1702 entity_tick(cfs_rq
, se
, queued
);
1707 * Share the fairness runtime between parent and child, thus the
1708 * total amount of pressure for CPU stays equal - new tasks
1709 * get a chance to run but frequent forkers are not allowed to
1710 * monopolize the CPU. Note: the parent runqueue is locked,
1711 * the child is not running yet.
1713 static void task_new_fair(struct rq
*rq
, struct task_struct
*p
)
1715 struct cfs_rq
*cfs_rq
= task_cfs_rq(p
);
1716 struct sched_entity
*se
= &p
->se
, *curr
= cfs_rq
->curr
;
1717 int this_cpu
= smp_processor_id();
1719 sched_info_queued(p
);
1721 update_curr(cfs_rq
);
1722 place_entity(cfs_rq
, se
, 1);
1724 /* 'curr' will be NULL if the child belongs to a different group */
1725 if (sysctl_sched_child_runs_first
&& this_cpu
== task_cpu(p
) &&
1726 curr
&& curr
->vruntime
< se
->vruntime
) {
1728 * Upon rescheduling, sched_class::put_prev_task() will place
1729 * 'current' within the tree based on its new key value.
1731 swap(curr
->vruntime
, se
->vruntime
);
1732 resched_task(rq
->curr
);
1735 enqueue_task_fair(rq
, p
, 0);
1739 * Priority of the task has changed. Check to see if we preempt
1742 static void prio_changed_fair(struct rq
*rq
, struct task_struct
*p
,
1743 int oldprio
, int running
)
1746 * Reschedule if we are currently running on this runqueue and
1747 * our priority decreased, or if we are not currently running on
1748 * this runqueue and our priority is higher than the current's
1751 if (p
->prio
> oldprio
)
1752 resched_task(rq
->curr
);
1754 check_preempt_curr(rq
, p
, 0);
1758 * We switched to the sched_fair class.
1760 static void switched_to_fair(struct rq
*rq
, struct task_struct
*p
,
1764 * We were most likely switched from sched_rt, so
1765 * kick off the schedule if running, otherwise just see
1766 * if we can still preempt the current task.
1769 resched_task(rq
->curr
);
1771 check_preempt_curr(rq
, p
, 0);
1774 /* Account for a task changing its policy or group.
1776 * This routine is mostly called to set cfs_rq->curr field when a task
1777 * migrates between groups/classes.
1779 static void set_curr_task_fair(struct rq
*rq
)
1781 struct sched_entity
*se
= &rq
->curr
->se
;
1783 for_each_sched_entity(se
)
1784 set_next_entity(cfs_rq_of(se
), se
);
1787 #ifdef CONFIG_FAIR_GROUP_SCHED
1788 static void moved_group_fair(struct task_struct
*p
)
1790 struct cfs_rq
*cfs_rq
= task_cfs_rq(p
);
1792 update_curr(cfs_rq
);
1793 place_entity(cfs_rq
, &p
->se
, 1);
1798 * All the scheduling class methods:
1800 static const struct sched_class fair_sched_class
= {
1801 .next
= &idle_sched_class
,
1802 .enqueue_task
= enqueue_task_fair
,
1803 .dequeue_task
= dequeue_task_fair
,
1804 .yield_task
= yield_task_fair
,
1806 .check_preempt_curr
= check_preempt_wakeup
,
1808 .pick_next_task
= pick_next_task_fair
,
1809 .put_prev_task
= put_prev_task_fair
,
1812 .select_task_rq
= select_task_rq_fair
,
1814 .load_balance
= load_balance_fair
,
1815 .move_one_task
= move_one_task_fair
,
1818 .set_curr_task
= set_curr_task_fair
,
1819 .task_tick
= task_tick_fair
,
1820 .task_new
= task_new_fair
,
1822 .prio_changed
= prio_changed_fair
,
1823 .switched_to
= switched_to_fair
,
1825 #ifdef CONFIG_FAIR_GROUP_SCHED
1826 .moved_group
= moved_group_fair
,
1830 #ifdef CONFIG_SCHED_DEBUG
1831 static void print_cfs_stats(struct seq_file
*m
, int cpu
)
1833 struct cfs_rq
*cfs_rq
;
1836 for_each_leaf_cfs_rq(cpu_rq(cpu
), cfs_rq
)
1837 print_cfs_rq(m
, cpu
, cfs_rq
);