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>
24 #include <linux/sched.h>
25 #include <linux/cpumask.h>
28 * Targeted preemption latency for CPU-bound tasks:
29 * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
31 * NOTE: this latency value is not the same as the concept of
32 * 'timeslice length' - timeslices in CFS are of variable length
33 * and have no persistent notion like in traditional, time-slice
34 * based scheduling concepts.
36 * (to see the precise effective timeslice length of your workload,
37 * run vmstat and monitor the context-switches (cs) field)
39 unsigned int sysctl_sched_latency
= 6000000ULL;
40 unsigned int normalized_sysctl_sched_latency
= 6000000ULL;
43 * The initial- and re-scaling of tunables is configurable
44 * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
47 * SCHED_TUNABLESCALING_NONE - unscaled, always *1
48 * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
49 * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
51 enum sched_tunable_scaling sysctl_sched_tunable_scaling
52 = SCHED_TUNABLESCALING_LOG
;
55 * Minimal preemption granularity for CPU-bound tasks:
56 * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
58 unsigned int sysctl_sched_min_granularity
= 750000ULL;
59 unsigned int normalized_sysctl_sched_min_granularity
= 750000ULL;
62 * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
64 static unsigned int sched_nr_latency
= 8;
67 * After fork, child runs first. If set to 0 (default) then
68 * parent will (try to) run first.
70 unsigned int sysctl_sched_child_runs_first __read_mostly
;
73 * SCHED_OTHER wake-up granularity.
74 * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
76 * This option delays the preemption effects of decoupled workloads
77 * and reduces their over-scheduling. Synchronous workloads will still
78 * have immediate wakeup/sleep latencies.
80 unsigned int sysctl_sched_wakeup_granularity
= 1000000UL;
81 unsigned int normalized_sysctl_sched_wakeup_granularity
= 1000000UL;
83 const_debug
unsigned int sysctl_sched_migration_cost
= 500000UL;
86 * The exponential sliding window over which load is averaged for shares
90 unsigned int __read_mostly sysctl_sched_shares_window
= 10000000UL;
92 static const struct sched_class fair_sched_class
;
94 /**************************************************************
95 * CFS operations on generic schedulable entities:
98 #ifdef CONFIG_FAIR_GROUP_SCHED
100 /* cpu runqueue to which this cfs_rq is attached */
101 static inline struct rq
*rq_of(struct cfs_rq
*cfs_rq
)
106 /* An entity is a task if it doesn't "own" a runqueue */
107 #define entity_is_task(se) (!se->my_q)
109 static inline struct task_struct
*task_of(struct sched_entity
*se
)
111 #ifdef CONFIG_SCHED_DEBUG
112 WARN_ON_ONCE(!entity_is_task(se
));
114 return container_of(se
, struct task_struct
, se
);
117 /* Walk up scheduling entities hierarchy */
118 #define for_each_sched_entity(se) \
119 for (; se; se = se->parent)
121 static inline struct cfs_rq
*task_cfs_rq(struct task_struct
*p
)
126 /* runqueue on which this entity is (to be) queued */
127 static inline struct cfs_rq
*cfs_rq_of(struct sched_entity
*se
)
132 /* runqueue "owned" by this group */
133 static inline struct cfs_rq
*group_cfs_rq(struct sched_entity
*grp
)
138 /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on
139 * another cpu ('this_cpu')
141 static inline struct cfs_rq
*cpu_cfs_rq(struct cfs_rq
*cfs_rq
, int this_cpu
)
143 return cfs_rq
->tg
->cfs_rq
[this_cpu
];
146 static inline void list_add_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
148 if (!cfs_rq
->on_list
) {
150 * Ensure we either appear before our parent (if already
151 * enqueued) or force our parent to appear after us when it is
152 * enqueued. The fact that we always enqueue bottom-up
153 * reduces this to two cases.
155 if (cfs_rq
->tg
->parent
&&
156 cfs_rq
->tg
->parent
->cfs_rq
[cpu_of(rq_of(cfs_rq
))]->on_list
) {
157 list_add_rcu(&cfs_rq
->leaf_cfs_rq_list
,
158 &rq_of(cfs_rq
)->leaf_cfs_rq_list
);
160 list_add_tail_rcu(&cfs_rq
->leaf_cfs_rq_list
,
161 &rq_of(cfs_rq
)->leaf_cfs_rq_list
);
168 static inline void list_del_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
170 if (cfs_rq
->on_list
) {
171 list_del_rcu(&cfs_rq
->leaf_cfs_rq_list
);
176 /* Iterate thr' all leaf cfs_rq's on a runqueue */
177 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
178 list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
180 /* Do the two (enqueued) entities belong to the same group ? */
182 is_same_group(struct sched_entity
*se
, struct sched_entity
*pse
)
184 if (se
->cfs_rq
== pse
->cfs_rq
)
190 static inline struct sched_entity
*parent_entity(struct sched_entity
*se
)
195 /* return depth at which a sched entity is present in the hierarchy */
196 static inline int depth_se(struct sched_entity
*se
)
200 for_each_sched_entity(se
)
207 find_matching_se(struct sched_entity
**se
, struct sched_entity
**pse
)
209 int se_depth
, pse_depth
;
212 * preemption test can be made between sibling entities who are in the
213 * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
214 * both tasks until we find their ancestors who are siblings of common
218 /* First walk up until both entities are at same depth */
219 se_depth
= depth_se(*se
);
220 pse_depth
= depth_se(*pse
);
222 while (se_depth
> pse_depth
) {
224 *se
= parent_entity(*se
);
227 while (pse_depth
> se_depth
) {
229 *pse
= parent_entity(*pse
);
232 while (!is_same_group(*se
, *pse
)) {
233 *se
= parent_entity(*se
);
234 *pse
= parent_entity(*pse
);
238 #else /* !CONFIG_FAIR_GROUP_SCHED */
240 static inline struct task_struct
*task_of(struct sched_entity
*se
)
242 return container_of(se
, struct task_struct
, se
);
245 static inline struct rq
*rq_of(struct cfs_rq
*cfs_rq
)
247 return container_of(cfs_rq
, struct rq
, cfs
);
250 #define entity_is_task(se) 1
252 #define for_each_sched_entity(se) \
253 for (; se; se = NULL)
255 static inline struct cfs_rq
*task_cfs_rq(struct task_struct
*p
)
257 return &task_rq(p
)->cfs
;
260 static inline struct cfs_rq
*cfs_rq_of(struct sched_entity
*se
)
262 struct task_struct
*p
= task_of(se
);
263 struct rq
*rq
= task_rq(p
);
268 /* runqueue "owned" by this group */
269 static inline struct cfs_rq
*group_cfs_rq(struct sched_entity
*grp
)
274 static inline struct cfs_rq
*cpu_cfs_rq(struct cfs_rq
*cfs_rq
, int this_cpu
)
276 return &cpu_rq(this_cpu
)->cfs
;
279 static inline void list_add_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
283 static inline void list_del_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
287 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
288 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
291 is_same_group(struct sched_entity
*se
, struct sched_entity
*pse
)
296 static inline struct sched_entity
*parent_entity(struct sched_entity
*se
)
302 find_matching_se(struct sched_entity
**se
, struct sched_entity
**pse
)
306 #endif /* CONFIG_FAIR_GROUP_SCHED */
309 /**************************************************************
310 * Scheduling class tree data structure manipulation methods:
313 static inline u64
max_vruntime(u64 min_vruntime
, u64 vruntime
)
315 s64 delta
= (s64
)(vruntime
- min_vruntime
);
317 min_vruntime
= vruntime
;
322 static inline u64
min_vruntime(u64 min_vruntime
, u64 vruntime
)
324 s64 delta
= (s64
)(vruntime
- min_vruntime
);
326 min_vruntime
= vruntime
;
331 static inline int entity_before(struct sched_entity
*a
,
332 struct sched_entity
*b
)
334 return (s64
)(a
->vruntime
- b
->vruntime
) < 0;
337 static inline s64
entity_key(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
339 return se
->vruntime
- cfs_rq
->min_vruntime
;
342 static void update_min_vruntime(struct cfs_rq
*cfs_rq
)
344 u64 vruntime
= cfs_rq
->min_vruntime
;
347 vruntime
= cfs_rq
->curr
->vruntime
;
349 if (cfs_rq
->rb_leftmost
) {
350 struct sched_entity
*se
= rb_entry(cfs_rq
->rb_leftmost
,
355 vruntime
= se
->vruntime
;
357 vruntime
= min_vruntime(vruntime
, se
->vruntime
);
360 cfs_rq
->min_vruntime
= max_vruntime(cfs_rq
->min_vruntime
, vruntime
);
364 * Enqueue an entity into the rb-tree:
366 static void __enqueue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
368 struct rb_node
**link
= &cfs_rq
->tasks_timeline
.rb_node
;
369 struct rb_node
*parent
= NULL
;
370 struct sched_entity
*entry
;
371 s64 key
= entity_key(cfs_rq
, se
);
375 * Find the right place in the rbtree:
379 entry
= rb_entry(parent
, struct sched_entity
, run_node
);
381 * We dont care about collisions. Nodes with
382 * the same key stay together.
384 if (key
< entity_key(cfs_rq
, entry
)) {
385 link
= &parent
->rb_left
;
387 link
= &parent
->rb_right
;
393 * Maintain a cache of leftmost tree entries (it is frequently
397 cfs_rq
->rb_leftmost
= &se
->run_node
;
399 rb_link_node(&se
->run_node
, parent
, link
);
400 rb_insert_color(&se
->run_node
, &cfs_rq
->tasks_timeline
);
403 static void __dequeue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
405 if (cfs_rq
->rb_leftmost
== &se
->run_node
) {
406 struct rb_node
*next_node
;
408 next_node
= rb_next(&se
->run_node
);
409 cfs_rq
->rb_leftmost
= next_node
;
412 rb_erase(&se
->run_node
, &cfs_rq
->tasks_timeline
);
415 static struct sched_entity
*__pick_first_entity(struct cfs_rq
*cfs_rq
)
417 struct rb_node
*left
= cfs_rq
->rb_leftmost
;
422 return rb_entry(left
, struct sched_entity
, run_node
);
425 static struct sched_entity
*__pick_next_entity(struct sched_entity
*se
)
427 struct rb_node
*next
= rb_next(&se
->run_node
);
432 return rb_entry(next
, struct sched_entity
, run_node
);
435 #ifdef CONFIG_SCHED_DEBUG
436 static struct sched_entity
*__pick_last_entity(struct cfs_rq
*cfs_rq
)
438 struct rb_node
*last
= rb_last(&cfs_rq
->tasks_timeline
);
443 return rb_entry(last
, struct sched_entity
, run_node
);
446 /**************************************************************
447 * Scheduling class statistics methods:
450 int sched_proc_update_handler(struct ctl_table
*table
, int write
,
451 void __user
*buffer
, size_t *lenp
,
454 int ret
= proc_dointvec_minmax(table
, write
, buffer
, lenp
, ppos
);
455 int factor
= get_update_sysctl_factor();
460 sched_nr_latency
= DIV_ROUND_UP(sysctl_sched_latency
,
461 sysctl_sched_min_granularity
);
463 #define WRT_SYSCTL(name) \
464 (normalized_sysctl_##name = sysctl_##name / (factor))
465 WRT_SYSCTL(sched_min_granularity
);
466 WRT_SYSCTL(sched_latency
);
467 WRT_SYSCTL(sched_wakeup_granularity
);
477 static inline unsigned long
478 calc_delta_fair(unsigned long delta
, struct sched_entity
*se
)
480 if (unlikely(se
->load
.weight
!= NICE_0_LOAD
))
481 delta
= calc_delta_mine(delta
, NICE_0_LOAD
, &se
->load
);
487 * The idea is to set a period in which each task runs once.
489 * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
490 * this period because otherwise the slices get too small.
492 * p = (nr <= nl) ? l : l*nr/nl
494 static u64
__sched_period(unsigned long nr_running
)
496 u64 period
= sysctl_sched_latency
;
497 unsigned long nr_latency
= sched_nr_latency
;
499 if (unlikely(nr_running
> nr_latency
)) {
500 period
= sysctl_sched_min_granularity
;
501 period
*= nr_running
;
508 * We calculate the wall-time slice from the period by taking a part
509 * proportional to the weight.
513 static u64
sched_slice(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
515 u64 slice
= __sched_period(cfs_rq
->nr_running
+ !se
->on_rq
);
517 for_each_sched_entity(se
) {
518 struct load_weight
*load
;
519 struct load_weight lw
;
521 cfs_rq
= cfs_rq_of(se
);
522 load
= &cfs_rq
->load
;
524 if (unlikely(!se
->on_rq
)) {
527 update_load_add(&lw
, se
->load
.weight
);
530 slice
= calc_delta_mine(slice
, se
->load
.weight
, load
);
536 * We calculate the vruntime slice of a to be inserted task
540 static u64
sched_vslice(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
542 return calc_delta_fair(sched_slice(cfs_rq
, se
), se
);
545 static void update_cfs_load(struct cfs_rq
*cfs_rq
, int global_update
);
546 static void update_cfs_shares(struct cfs_rq
*cfs_rq
);
549 * Update the current task's runtime statistics. Skip current tasks that
550 * are not in our scheduling class.
553 __update_curr(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
,
554 unsigned long delta_exec
)
556 unsigned long delta_exec_weighted
;
558 schedstat_set(curr
->statistics
.exec_max
,
559 max((u64
)delta_exec
, curr
->statistics
.exec_max
));
561 curr
->sum_exec_runtime
+= delta_exec
;
562 schedstat_add(cfs_rq
, exec_clock
, delta_exec
);
563 delta_exec_weighted
= calc_delta_fair(delta_exec
, curr
);
565 curr
->vruntime
+= delta_exec_weighted
;
566 update_min_vruntime(cfs_rq
);
568 #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
569 cfs_rq
->load_unacc_exec_time
+= delta_exec
;
573 static void update_curr(struct cfs_rq
*cfs_rq
)
575 struct sched_entity
*curr
= cfs_rq
->curr
;
576 u64 now
= rq_of(cfs_rq
)->clock_task
;
577 unsigned long delta_exec
;
583 * Get the amount of time the current task was running
584 * since the last time we changed load (this cannot
585 * overflow on 32 bits):
587 delta_exec
= (unsigned long)(now
- curr
->exec_start
);
591 __update_curr(cfs_rq
, curr
, delta_exec
);
592 curr
->exec_start
= now
;
594 if (entity_is_task(curr
)) {
595 struct task_struct
*curtask
= task_of(curr
);
597 trace_sched_stat_runtime(curtask
, delta_exec
, curr
->vruntime
);
598 cpuacct_charge(curtask
, delta_exec
);
599 account_group_exec_runtime(curtask
, delta_exec
);
604 update_stats_wait_start(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
606 schedstat_set(se
->statistics
.wait_start
, rq_of(cfs_rq
)->clock
);
610 * Task is being enqueued - update stats:
612 static void update_stats_enqueue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
615 * Are we enqueueing a waiting task? (for current tasks
616 * a dequeue/enqueue event is a NOP)
618 if (se
!= cfs_rq
->curr
)
619 update_stats_wait_start(cfs_rq
, se
);
623 update_stats_wait_end(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
625 schedstat_set(se
->statistics
.wait_max
, max(se
->statistics
.wait_max
,
626 rq_of(cfs_rq
)->clock
- se
->statistics
.wait_start
));
627 schedstat_set(se
->statistics
.wait_count
, se
->statistics
.wait_count
+ 1);
628 schedstat_set(se
->statistics
.wait_sum
, se
->statistics
.wait_sum
+
629 rq_of(cfs_rq
)->clock
- se
->statistics
.wait_start
);
630 #ifdef CONFIG_SCHEDSTATS
631 if (entity_is_task(se
)) {
632 trace_sched_stat_wait(task_of(se
),
633 rq_of(cfs_rq
)->clock
- se
->statistics
.wait_start
);
636 schedstat_set(se
->statistics
.wait_start
, 0);
640 update_stats_dequeue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
643 * Mark the end of the wait period if dequeueing a
646 if (se
!= cfs_rq
->curr
)
647 update_stats_wait_end(cfs_rq
, se
);
651 * We are picking a new current task - update its stats:
654 update_stats_curr_start(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
657 * We are starting a new run period:
659 se
->exec_start
= rq_of(cfs_rq
)->clock_task
;
662 /**************************************************
663 * Scheduling class queueing methods:
666 #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
668 add_cfs_task_weight(struct cfs_rq
*cfs_rq
, unsigned long weight
)
670 cfs_rq
->task_weight
+= weight
;
674 add_cfs_task_weight(struct cfs_rq
*cfs_rq
, unsigned long weight
)
680 account_entity_enqueue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
682 update_load_add(&cfs_rq
->load
, se
->load
.weight
);
683 if (!parent_entity(se
))
684 inc_cpu_load(rq_of(cfs_rq
), se
->load
.weight
);
685 if (entity_is_task(se
)) {
686 add_cfs_task_weight(cfs_rq
, se
->load
.weight
);
687 list_add(&se
->group_node
, &cfs_rq
->tasks
);
689 cfs_rq
->nr_running
++;
693 account_entity_dequeue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
695 update_load_sub(&cfs_rq
->load
, se
->load
.weight
);
696 if (!parent_entity(se
))
697 dec_cpu_load(rq_of(cfs_rq
), se
->load
.weight
);
698 if (entity_is_task(se
)) {
699 add_cfs_task_weight(cfs_rq
, -se
->load
.weight
);
700 list_del_init(&se
->group_node
);
702 cfs_rq
->nr_running
--;
705 #ifdef CONFIG_FAIR_GROUP_SCHED
707 static void update_cfs_rq_load_contribution(struct cfs_rq
*cfs_rq
,
710 struct task_group
*tg
= cfs_rq
->tg
;
713 load_avg
= div64_u64(cfs_rq
->load_avg
, cfs_rq
->load_period
+1);
714 load_avg
-= cfs_rq
->load_contribution
;
716 if (global_update
|| abs(load_avg
) > cfs_rq
->load_contribution
/ 8) {
717 atomic_add(load_avg
, &tg
->load_weight
);
718 cfs_rq
->load_contribution
+= load_avg
;
722 static void update_cfs_load(struct cfs_rq
*cfs_rq
, int global_update
)
724 u64 period
= sysctl_sched_shares_window
;
726 unsigned long load
= cfs_rq
->load
.weight
;
728 if (cfs_rq
->tg
== &root_task_group
)
731 now
= rq_of(cfs_rq
)->clock_task
;
732 delta
= now
- cfs_rq
->load_stamp
;
734 /* truncate load history at 4 idle periods */
735 if (cfs_rq
->load_stamp
> cfs_rq
->load_last
&&
736 now
- cfs_rq
->load_last
> 4 * period
) {
737 cfs_rq
->load_period
= 0;
738 cfs_rq
->load_avg
= 0;
742 cfs_rq
->load_stamp
= now
;
743 cfs_rq
->load_unacc_exec_time
= 0;
744 cfs_rq
->load_period
+= delta
;
746 cfs_rq
->load_last
= now
;
747 cfs_rq
->load_avg
+= delta
* load
;
750 /* consider updating load contribution on each fold or truncate */
751 if (global_update
|| cfs_rq
->load_period
> period
752 || !cfs_rq
->load_period
)
753 update_cfs_rq_load_contribution(cfs_rq
, global_update
);
755 while (cfs_rq
->load_period
> period
) {
757 * Inline assembly required to prevent the compiler
758 * optimising this loop into a divmod call.
759 * See __iter_div_u64_rem() for another example of this.
761 asm("" : "+rm" (cfs_rq
->load_period
));
762 cfs_rq
->load_period
/= 2;
763 cfs_rq
->load_avg
/= 2;
766 if (!cfs_rq
->curr
&& !cfs_rq
->nr_running
&& !cfs_rq
->load_avg
)
767 list_del_leaf_cfs_rq(cfs_rq
);
770 static long calc_cfs_shares(struct cfs_rq
*cfs_rq
, struct task_group
*tg
)
772 long load_weight
, load
, shares
;
774 load
= cfs_rq
->load
.weight
;
776 load_weight
= atomic_read(&tg
->load_weight
);
778 load_weight
-= cfs_rq
->load_contribution
;
780 shares
= (tg
->shares
* load
);
782 shares
/= load_weight
;
784 if (shares
< MIN_SHARES
)
786 if (shares
> tg
->shares
)
792 static void update_entity_shares_tick(struct cfs_rq
*cfs_rq
)
794 if (cfs_rq
->load_unacc_exec_time
> sysctl_sched_shares_window
) {
795 update_cfs_load(cfs_rq
, 0);
796 update_cfs_shares(cfs_rq
);
799 # else /* CONFIG_SMP */
800 static void update_cfs_load(struct cfs_rq
*cfs_rq
, int global_update
)
804 static inline long calc_cfs_shares(struct cfs_rq
*cfs_rq
, struct task_group
*tg
)
809 static inline void update_entity_shares_tick(struct cfs_rq
*cfs_rq
)
812 # endif /* CONFIG_SMP */
813 static void reweight_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
,
814 unsigned long weight
)
817 /* commit outstanding execution time */
818 if (cfs_rq
->curr
== se
)
820 account_entity_dequeue(cfs_rq
, se
);
823 update_load_set(&se
->load
, weight
);
826 account_entity_enqueue(cfs_rq
, se
);
829 static void update_cfs_shares(struct cfs_rq
*cfs_rq
)
831 struct task_group
*tg
;
832 struct sched_entity
*se
;
836 se
= tg
->se
[cpu_of(rq_of(cfs_rq
))];
840 if (likely(se
->load
.weight
== tg
->shares
))
843 shares
= calc_cfs_shares(cfs_rq
, tg
);
845 reweight_entity(cfs_rq_of(se
), se
, shares
);
847 #else /* CONFIG_FAIR_GROUP_SCHED */
848 static void update_cfs_load(struct cfs_rq
*cfs_rq
, int global_update
)
852 static inline void update_cfs_shares(struct cfs_rq
*cfs_rq
)
856 static inline void update_entity_shares_tick(struct cfs_rq
*cfs_rq
)
859 #endif /* CONFIG_FAIR_GROUP_SCHED */
861 static void enqueue_sleeper(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
863 #ifdef CONFIG_SCHEDSTATS
864 struct task_struct
*tsk
= NULL
;
866 if (entity_is_task(se
))
869 if (se
->statistics
.sleep_start
) {
870 u64 delta
= rq_of(cfs_rq
)->clock
- se
->statistics
.sleep_start
;
875 if (unlikely(delta
> se
->statistics
.sleep_max
))
876 se
->statistics
.sleep_max
= delta
;
878 se
->statistics
.sleep_start
= 0;
879 se
->statistics
.sum_sleep_runtime
+= delta
;
882 account_scheduler_latency(tsk
, delta
>> 10, 1);
883 trace_sched_stat_sleep(tsk
, delta
);
886 if (se
->statistics
.block_start
) {
887 u64 delta
= rq_of(cfs_rq
)->clock
- se
->statistics
.block_start
;
892 if (unlikely(delta
> se
->statistics
.block_max
))
893 se
->statistics
.block_max
= delta
;
895 se
->statistics
.block_start
= 0;
896 se
->statistics
.sum_sleep_runtime
+= delta
;
899 if (tsk
->in_iowait
) {
900 se
->statistics
.iowait_sum
+= delta
;
901 se
->statistics
.iowait_count
++;
902 trace_sched_stat_iowait(tsk
, delta
);
906 * Blocking time is in units of nanosecs, so shift by
907 * 20 to get a milliseconds-range estimation of the
908 * amount of time that the task spent sleeping:
910 if (unlikely(prof_on
== SLEEP_PROFILING
)) {
911 profile_hits(SLEEP_PROFILING
,
912 (void *)get_wchan(tsk
),
915 account_scheduler_latency(tsk
, delta
>> 10, 0);
921 static void check_spread(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
923 #ifdef CONFIG_SCHED_DEBUG
924 s64 d
= se
->vruntime
- cfs_rq
->min_vruntime
;
929 if (d
> 3*sysctl_sched_latency
)
930 schedstat_inc(cfs_rq
, nr_spread_over
);
935 place_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int initial
)
937 u64 vruntime
= cfs_rq
->min_vruntime
;
940 * The 'current' period is already promised to the current tasks,
941 * however the extra weight of the new task will slow them down a
942 * little, place the new task so that it fits in the slot that
943 * stays open at the end.
945 if (initial
&& sched_feat(START_DEBIT
))
946 vruntime
+= sched_vslice(cfs_rq
, se
);
948 /* sleeps up to a single latency don't count. */
950 unsigned long thresh
= sysctl_sched_latency
;
953 * Halve their sleep time's effect, to allow
954 * for a gentler effect of sleepers:
956 if (sched_feat(GENTLE_FAIR_SLEEPERS
))
962 /* ensure we never gain time by being placed backwards. */
963 vruntime
= max_vruntime(se
->vruntime
, vruntime
);
965 se
->vruntime
= vruntime
;
969 enqueue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int flags
)
972 * Update the normalized vruntime before updating min_vruntime
973 * through callig update_curr().
975 if (!(flags
& ENQUEUE_WAKEUP
) || (flags
& ENQUEUE_WAKING
))
976 se
->vruntime
+= cfs_rq
->min_vruntime
;
979 * Update run-time statistics of the 'current'.
982 update_cfs_load(cfs_rq
, 0);
983 account_entity_enqueue(cfs_rq
, se
);
984 update_cfs_shares(cfs_rq
);
986 if (flags
& ENQUEUE_WAKEUP
) {
987 place_entity(cfs_rq
, se
, 0);
988 enqueue_sleeper(cfs_rq
, se
);
991 update_stats_enqueue(cfs_rq
, se
);
992 check_spread(cfs_rq
, se
);
993 if (se
!= cfs_rq
->curr
)
994 __enqueue_entity(cfs_rq
, se
);
997 if (cfs_rq
->nr_running
== 1)
998 list_add_leaf_cfs_rq(cfs_rq
);
1001 static void __clear_buddies_last(struct sched_entity
*se
)
1003 for_each_sched_entity(se
) {
1004 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
1005 if (cfs_rq
->last
== se
)
1006 cfs_rq
->last
= NULL
;
1012 static void __clear_buddies_next(struct sched_entity
*se
)
1014 for_each_sched_entity(se
) {
1015 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
1016 if (cfs_rq
->next
== se
)
1017 cfs_rq
->next
= NULL
;
1023 static void __clear_buddies_skip(struct sched_entity
*se
)
1025 for_each_sched_entity(se
) {
1026 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
1027 if (cfs_rq
->skip
== se
)
1028 cfs_rq
->skip
= NULL
;
1034 static void clear_buddies(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
1036 if (cfs_rq
->last
== se
)
1037 __clear_buddies_last(se
);
1039 if (cfs_rq
->next
== se
)
1040 __clear_buddies_next(se
);
1042 if (cfs_rq
->skip
== se
)
1043 __clear_buddies_skip(se
);
1047 dequeue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int flags
)
1050 * Update run-time statistics of the 'current'.
1052 update_curr(cfs_rq
);
1054 update_stats_dequeue(cfs_rq
, se
);
1055 if (flags
& DEQUEUE_SLEEP
) {
1056 #ifdef CONFIG_SCHEDSTATS
1057 if (entity_is_task(se
)) {
1058 struct task_struct
*tsk
= task_of(se
);
1060 if (tsk
->state
& TASK_INTERRUPTIBLE
)
1061 se
->statistics
.sleep_start
= rq_of(cfs_rq
)->clock
;
1062 if (tsk
->state
& TASK_UNINTERRUPTIBLE
)
1063 se
->statistics
.block_start
= rq_of(cfs_rq
)->clock
;
1068 clear_buddies(cfs_rq
, se
);
1070 if (se
!= cfs_rq
->curr
)
1071 __dequeue_entity(cfs_rq
, se
);
1073 update_cfs_load(cfs_rq
, 0);
1074 account_entity_dequeue(cfs_rq
, se
);
1075 update_min_vruntime(cfs_rq
);
1076 update_cfs_shares(cfs_rq
);
1079 * Normalize the entity after updating the min_vruntime because the
1080 * update can refer to the ->curr item and we need to reflect this
1081 * movement in our normalized position.
1083 if (!(flags
& DEQUEUE_SLEEP
))
1084 se
->vruntime
-= cfs_rq
->min_vruntime
;
1088 * Preempt the current task with a newly woken task if needed:
1091 check_preempt_tick(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
)
1093 unsigned long ideal_runtime
, delta_exec
;
1095 ideal_runtime
= sched_slice(cfs_rq
, curr
);
1096 delta_exec
= curr
->sum_exec_runtime
- curr
->prev_sum_exec_runtime
;
1097 if (delta_exec
> ideal_runtime
) {
1098 resched_task(rq_of(cfs_rq
)->curr
);
1100 * The current task ran long enough, ensure it doesn't get
1101 * re-elected due to buddy favours.
1103 clear_buddies(cfs_rq
, curr
);
1108 * Ensure that a task that missed wakeup preemption by a
1109 * narrow margin doesn't have to wait for a full slice.
1110 * This also mitigates buddy induced latencies under load.
1112 if (!sched_feat(WAKEUP_PREEMPT
))
1115 if (delta_exec
< sysctl_sched_min_granularity
)
1118 if (cfs_rq
->nr_running
> 1) {
1119 struct sched_entity
*se
= __pick_first_entity(cfs_rq
);
1120 s64 delta
= curr
->vruntime
- se
->vruntime
;
1125 if (delta
> ideal_runtime
)
1126 resched_task(rq_of(cfs_rq
)->curr
);
1131 set_next_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
1133 /* 'current' is not kept within the tree. */
1136 * Any task has to be enqueued before it get to execute on
1137 * a CPU. So account for the time it spent waiting on the
1140 update_stats_wait_end(cfs_rq
, se
);
1141 __dequeue_entity(cfs_rq
, se
);
1144 update_stats_curr_start(cfs_rq
, se
);
1146 #ifdef CONFIG_SCHEDSTATS
1148 * Track our maximum slice length, if the CPU's load is at
1149 * least twice that of our own weight (i.e. dont track it
1150 * when there are only lesser-weight tasks around):
1152 if (rq_of(cfs_rq
)->load
.weight
>= 2*se
->load
.weight
) {
1153 se
->statistics
.slice_max
= max(se
->statistics
.slice_max
,
1154 se
->sum_exec_runtime
- se
->prev_sum_exec_runtime
);
1157 se
->prev_sum_exec_runtime
= se
->sum_exec_runtime
;
1161 wakeup_preempt_entity(struct sched_entity
*curr
, struct sched_entity
*se
);
1164 * Pick the next process, keeping these things in mind, in this order:
1165 * 1) keep things fair between processes/task groups
1166 * 2) pick the "next" process, since someone really wants that to run
1167 * 3) pick the "last" process, for cache locality
1168 * 4) do not run the "skip" process, if something else is available
1170 static struct sched_entity
*pick_next_entity(struct cfs_rq
*cfs_rq
)
1172 struct sched_entity
*se
= __pick_first_entity(cfs_rq
);
1173 struct sched_entity
*left
= se
;
1176 * Avoid running the skip buddy, if running something else can
1177 * be done without getting too unfair.
1179 if (cfs_rq
->skip
== se
) {
1180 struct sched_entity
*second
= __pick_next_entity(se
);
1181 if (second
&& wakeup_preempt_entity(second
, left
) < 1)
1186 * Prefer last buddy, try to return the CPU to a preempted task.
1188 if (cfs_rq
->last
&& wakeup_preempt_entity(cfs_rq
->last
, left
) < 1)
1192 * Someone really wants this to run. If it's not unfair, run it.
1194 if (cfs_rq
->next
&& wakeup_preempt_entity(cfs_rq
->next
, left
) < 1)
1197 clear_buddies(cfs_rq
, se
);
1202 static void put_prev_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*prev
)
1205 * If still on the runqueue then deactivate_task()
1206 * was not called and update_curr() has to be done:
1209 update_curr(cfs_rq
);
1211 check_spread(cfs_rq
, prev
);
1213 update_stats_wait_start(cfs_rq
, prev
);
1214 /* Put 'current' back into the tree. */
1215 __enqueue_entity(cfs_rq
, prev
);
1217 cfs_rq
->curr
= NULL
;
1221 entity_tick(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
, int queued
)
1224 * Update run-time statistics of the 'current'.
1226 update_curr(cfs_rq
);
1229 * Update share accounting for long-running entities.
1231 update_entity_shares_tick(cfs_rq
);
1233 #ifdef CONFIG_SCHED_HRTICK
1235 * queued ticks are scheduled to match the slice, so don't bother
1236 * validating it and just reschedule.
1239 resched_task(rq_of(cfs_rq
)->curr
);
1243 * don't let the period tick interfere with the hrtick preemption
1245 if (!sched_feat(DOUBLE_TICK
) &&
1246 hrtimer_active(&rq_of(cfs_rq
)->hrtick_timer
))
1250 if (cfs_rq
->nr_running
> 1 || !sched_feat(WAKEUP_PREEMPT
))
1251 check_preempt_tick(cfs_rq
, curr
);
1254 /**************************************************
1255 * CFS operations on tasks:
1258 #ifdef CONFIG_SCHED_HRTICK
1259 static void hrtick_start_fair(struct rq
*rq
, struct task_struct
*p
)
1261 struct sched_entity
*se
= &p
->se
;
1262 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
1264 WARN_ON(task_rq(p
) != rq
);
1266 if (hrtick_enabled(rq
) && cfs_rq
->nr_running
> 1) {
1267 u64 slice
= sched_slice(cfs_rq
, se
);
1268 u64 ran
= se
->sum_exec_runtime
- se
->prev_sum_exec_runtime
;
1269 s64 delta
= slice
- ran
;
1278 * Don't schedule slices shorter than 10000ns, that just
1279 * doesn't make sense. Rely on vruntime for fairness.
1282 delta
= max_t(s64
, 10000LL, delta
);
1284 hrtick_start(rq
, delta
);
1289 * called from enqueue/dequeue and updates the hrtick when the
1290 * current task is from our class and nr_running is low enough
1293 static void hrtick_update(struct rq
*rq
)
1295 struct task_struct
*curr
= rq
->curr
;
1297 if (curr
->sched_class
!= &fair_sched_class
)
1300 if (cfs_rq_of(&curr
->se
)->nr_running
< sched_nr_latency
)
1301 hrtick_start_fair(rq
, curr
);
1303 #else /* !CONFIG_SCHED_HRTICK */
1305 hrtick_start_fair(struct rq
*rq
, struct task_struct
*p
)
1309 static inline void hrtick_update(struct rq
*rq
)
1315 * The enqueue_task method is called before nr_running is
1316 * increased. Here we update the fair scheduling stats and
1317 * then put the task into the rbtree:
1320 enqueue_task_fair(struct rq
*rq
, struct task_struct
*p
, int flags
)
1322 struct cfs_rq
*cfs_rq
;
1323 struct sched_entity
*se
= &p
->se
;
1325 for_each_sched_entity(se
) {
1328 cfs_rq
= cfs_rq_of(se
);
1329 enqueue_entity(cfs_rq
, se
, flags
);
1330 flags
= ENQUEUE_WAKEUP
;
1333 for_each_sched_entity(se
) {
1334 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
1336 update_cfs_load(cfs_rq
, 0);
1337 update_cfs_shares(cfs_rq
);
1344 * The dequeue_task method is called before nr_running is
1345 * decreased. We remove the task from the rbtree and
1346 * update the fair scheduling stats:
1348 static void dequeue_task_fair(struct rq
*rq
, struct task_struct
*p
, int flags
)
1350 struct cfs_rq
*cfs_rq
;
1351 struct sched_entity
*se
= &p
->se
;
1353 for_each_sched_entity(se
) {
1354 cfs_rq
= cfs_rq_of(se
);
1355 dequeue_entity(cfs_rq
, se
, flags
);
1357 /* Don't dequeue parent if it has other entities besides us */
1358 if (cfs_rq
->load
.weight
)
1360 flags
|= DEQUEUE_SLEEP
;
1363 for_each_sched_entity(se
) {
1364 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
1366 update_cfs_load(cfs_rq
, 0);
1367 update_cfs_shares(cfs_rq
);
1375 static void task_waking_fair(struct rq
*rq
, struct task_struct
*p
)
1377 struct sched_entity
*se
= &p
->se
;
1378 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
1380 se
->vruntime
-= cfs_rq
->min_vruntime
;
1383 #ifdef CONFIG_FAIR_GROUP_SCHED
1385 * effective_load() calculates the load change as seen from the root_task_group
1387 * Adding load to a group doesn't make a group heavier, but can cause movement
1388 * of group shares between cpus. Assuming the shares were perfectly aligned one
1389 * can calculate the shift in shares.
1391 static long effective_load(struct task_group
*tg
, int cpu
, long wl
, long wg
)
1393 struct sched_entity
*se
= tg
->se
[cpu
];
1398 for_each_sched_entity(se
) {
1402 w
= se
->my_q
->load
.weight
;
1404 /* use this cpu's instantaneous contribution */
1405 lw
= atomic_read(&tg
->load_weight
);
1406 lw
-= se
->my_q
->load_contribution
;
1411 if (lw
> 0 && wl
< lw
)
1412 wl
= (wl
* tg
->shares
) / lw
;
1416 /* zero point is MIN_SHARES */
1417 if (wl
< MIN_SHARES
)
1419 wl
-= se
->load
.weight
;
1428 static inline unsigned long effective_load(struct task_group
*tg
, int cpu
,
1429 unsigned long wl
, unsigned long wg
)
1436 static int wake_affine(struct sched_domain
*sd
, struct task_struct
*p
, int sync
)
1438 s64 this_load
, load
;
1439 int idx
, this_cpu
, prev_cpu
;
1440 unsigned long tl_per_task
;
1441 struct task_group
*tg
;
1442 unsigned long weight
;
1446 this_cpu
= smp_processor_id();
1447 prev_cpu
= task_cpu(p
);
1448 load
= source_load(prev_cpu
, idx
);
1449 this_load
= target_load(this_cpu
, idx
);
1452 * If sync wakeup then subtract the (maximum possible)
1453 * effect of the currently running task from the load
1454 * of the current CPU:
1458 tg
= task_group(current
);
1459 weight
= current
->se
.load
.weight
;
1461 this_load
+= effective_load(tg
, this_cpu
, -weight
, -weight
);
1462 load
+= effective_load(tg
, prev_cpu
, 0, -weight
);
1466 weight
= p
->se
.load
.weight
;
1469 * In low-load situations, where prev_cpu is idle and this_cpu is idle
1470 * due to the sync cause above having dropped this_load to 0, we'll
1471 * always have an imbalance, but there's really nothing you can do
1472 * about that, so that's good too.
1474 * Otherwise check if either cpus are near enough in load to allow this
1475 * task to be woken on this_cpu.
1477 if (this_load
> 0) {
1478 s64 this_eff_load
, prev_eff_load
;
1480 this_eff_load
= 100;
1481 this_eff_load
*= power_of(prev_cpu
);
1482 this_eff_load
*= this_load
+
1483 effective_load(tg
, this_cpu
, weight
, weight
);
1485 prev_eff_load
= 100 + (sd
->imbalance_pct
- 100) / 2;
1486 prev_eff_load
*= power_of(this_cpu
);
1487 prev_eff_load
*= load
+ effective_load(tg
, prev_cpu
, 0, weight
);
1489 balanced
= this_eff_load
<= prev_eff_load
;
1495 * If the currently running task will sleep within
1496 * a reasonable amount of time then attract this newly
1499 if (sync
&& balanced
)
1502 schedstat_inc(p
, se
.statistics
.nr_wakeups_affine_attempts
);
1503 tl_per_task
= cpu_avg_load_per_task(this_cpu
);
1506 (this_load
<= load
&&
1507 this_load
+ target_load(prev_cpu
, idx
) <= tl_per_task
)) {
1509 * This domain has SD_WAKE_AFFINE and
1510 * p is cache cold in this domain, and
1511 * there is no bad imbalance.
1513 schedstat_inc(sd
, ttwu_move_affine
);
1514 schedstat_inc(p
, se
.statistics
.nr_wakeups_affine
);
1522 * find_idlest_group finds and returns the least busy CPU group within the
1525 static struct sched_group
*
1526 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
,
1527 int this_cpu
, int load_idx
)
1529 struct sched_group
*idlest
= NULL
, *group
= sd
->groups
;
1530 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
1531 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
1534 unsigned long load
, avg_load
;
1538 /* Skip over this group if it has no CPUs allowed */
1539 if (!cpumask_intersects(sched_group_cpus(group
),
1543 local_group
= cpumask_test_cpu(this_cpu
,
1544 sched_group_cpus(group
));
1546 /* Tally up the load of all CPUs in the group */
1549 for_each_cpu(i
, sched_group_cpus(group
)) {
1550 /* Bias balancing toward cpus of our domain */
1552 load
= source_load(i
, load_idx
);
1554 load
= target_load(i
, load_idx
);
1559 /* Adjust by relative CPU power of the group */
1560 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
1563 this_load
= avg_load
;
1564 } else if (avg_load
< min_load
) {
1565 min_load
= avg_load
;
1568 } while (group
= group
->next
, group
!= sd
->groups
);
1570 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1576 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1579 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1581 unsigned long load
, min_load
= ULONG_MAX
;
1585 /* Traverse only the allowed CPUs */
1586 for_each_cpu_and(i
, sched_group_cpus(group
), &p
->cpus_allowed
) {
1587 load
= weighted_cpuload(i
);
1589 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1599 * Try and locate an idle CPU in the sched_domain.
1601 static int select_idle_sibling(struct task_struct
*p
, int target
)
1603 int cpu
= smp_processor_id();
1604 int prev_cpu
= task_cpu(p
);
1605 struct sched_domain
*sd
;
1609 * If the task is going to be woken-up on this cpu and if it is
1610 * already idle, then it is the right target.
1612 if (target
== cpu
&& idle_cpu(cpu
))
1616 * If the task is going to be woken-up on the cpu where it previously
1617 * ran and if it is currently idle, then it the right target.
1619 if (target
== prev_cpu
&& idle_cpu(prev_cpu
))
1623 * Otherwise, iterate the domains and find an elegible idle cpu.
1625 for_each_domain(target
, sd
) {
1626 if (!(sd
->flags
& SD_SHARE_PKG_RESOURCES
))
1629 for_each_cpu_and(i
, sched_domain_span(sd
), &p
->cpus_allowed
) {
1637 * Lets stop looking for an idle sibling when we reached
1638 * the domain that spans the current cpu and prev_cpu.
1640 if (cpumask_test_cpu(cpu
, sched_domain_span(sd
)) &&
1641 cpumask_test_cpu(prev_cpu
, sched_domain_span(sd
)))
1649 * sched_balance_self: balance the current task (running on cpu) in domains
1650 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1653 * Balance, ie. select the least loaded group.
1655 * Returns the target CPU number, or the same CPU if no balancing is needed.
1657 * preempt must be disabled.
1660 select_task_rq_fair(struct rq
*rq
, struct task_struct
*p
, int sd_flag
, int wake_flags
)
1662 struct sched_domain
*tmp
, *affine_sd
= NULL
, *sd
= NULL
;
1663 int cpu
= smp_processor_id();
1664 int prev_cpu
= task_cpu(p
);
1666 int want_affine
= 0;
1668 int sync
= wake_flags
& WF_SYNC
;
1670 if (sd_flag
& SD_BALANCE_WAKE
) {
1671 if (cpumask_test_cpu(cpu
, &p
->cpus_allowed
))
1676 for_each_domain(cpu
, tmp
) {
1677 if (!(tmp
->flags
& SD_LOAD_BALANCE
))
1681 * If power savings logic is enabled for a domain, see if we
1682 * are not overloaded, if so, don't balance wider.
1684 if (tmp
->flags
& (SD_POWERSAVINGS_BALANCE
|SD_PREFER_LOCAL
)) {
1685 unsigned long power
= 0;
1686 unsigned long nr_running
= 0;
1687 unsigned long capacity
;
1690 for_each_cpu(i
, sched_domain_span(tmp
)) {
1691 power
+= power_of(i
);
1692 nr_running
+= cpu_rq(i
)->cfs
.nr_running
;
1695 capacity
= DIV_ROUND_CLOSEST(power
, SCHED_LOAD_SCALE
);
1697 if (tmp
->flags
& SD_POWERSAVINGS_BALANCE
)
1700 if (nr_running
< capacity
)
1705 * If both cpu and prev_cpu are part of this domain,
1706 * cpu is a valid SD_WAKE_AFFINE target.
1708 if (want_affine
&& (tmp
->flags
& SD_WAKE_AFFINE
) &&
1709 cpumask_test_cpu(prev_cpu
, sched_domain_span(tmp
))) {
1714 if (!want_sd
&& !want_affine
)
1717 if (!(tmp
->flags
& sd_flag
))
1725 if (cpu
== prev_cpu
|| wake_affine(affine_sd
, p
, sync
))
1726 return select_idle_sibling(p
, cpu
);
1728 return select_idle_sibling(p
, prev_cpu
);
1732 int load_idx
= sd
->forkexec_idx
;
1733 struct sched_group
*group
;
1736 if (!(sd
->flags
& sd_flag
)) {
1741 if (sd_flag
& SD_BALANCE_WAKE
)
1742 load_idx
= sd
->wake_idx
;
1744 group
= find_idlest_group(sd
, p
, cpu
, load_idx
);
1750 new_cpu
= find_idlest_cpu(group
, p
, cpu
);
1751 if (new_cpu
== -1 || new_cpu
== cpu
) {
1752 /* Now try balancing at a lower domain level of cpu */
1757 /* Now try balancing at a lower domain level of new_cpu */
1759 weight
= sd
->span_weight
;
1761 for_each_domain(cpu
, tmp
) {
1762 if (weight
<= tmp
->span_weight
)
1764 if (tmp
->flags
& sd_flag
)
1767 /* while loop will break here if sd == NULL */
1772 #endif /* CONFIG_SMP */
1774 static unsigned long
1775 wakeup_gran(struct sched_entity
*curr
, struct sched_entity
*se
)
1777 unsigned long gran
= sysctl_sched_wakeup_granularity
;
1780 * Since its curr running now, convert the gran from real-time
1781 * to virtual-time in his units.
1783 * By using 'se' instead of 'curr' we penalize light tasks, so
1784 * they get preempted easier. That is, if 'se' < 'curr' then
1785 * the resulting gran will be larger, therefore penalizing the
1786 * lighter, if otoh 'se' > 'curr' then the resulting gran will
1787 * be smaller, again penalizing the lighter task.
1789 * This is especially important for buddies when the leftmost
1790 * task is higher priority than the buddy.
1792 return calc_delta_fair(gran
, se
);
1796 * Should 'se' preempt 'curr'.
1810 wakeup_preempt_entity(struct sched_entity
*curr
, struct sched_entity
*se
)
1812 s64 gran
, vdiff
= curr
->vruntime
- se
->vruntime
;
1817 gran
= wakeup_gran(curr
, se
);
1824 static void set_last_buddy(struct sched_entity
*se
)
1826 if (likely(task_of(se
)->policy
!= SCHED_IDLE
)) {
1827 for_each_sched_entity(se
)
1828 cfs_rq_of(se
)->last
= se
;
1832 static void set_next_buddy(struct sched_entity
*se
)
1834 if (likely(task_of(se
)->policy
!= SCHED_IDLE
)) {
1835 for_each_sched_entity(se
)
1836 cfs_rq_of(se
)->next
= se
;
1840 static void set_skip_buddy(struct sched_entity
*se
)
1842 if (likely(task_of(se
)->policy
!= SCHED_IDLE
)) {
1843 for_each_sched_entity(se
)
1844 cfs_rq_of(se
)->skip
= se
;
1849 * Preempt the current task with a newly woken task if needed:
1851 static void check_preempt_wakeup(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1853 struct task_struct
*curr
= rq
->curr
;
1854 struct sched_entity
*se
= &curr
->se
, *pse
= &p
->se
;
1855 struct cfs_rq
*cfs_rq
= task_cfs_rq(curr
);
1856 int scale
= cfs_rq
->nr_running
>= sched_nr_latency
;
1858 if (unlikely(se
== pse
))
1861 if (sched_feat(NEXT_BUDDY
) && scale
&& !(wake_flags
& WF_FORK
))
1862 set_next_buddy(pse
);
1865 * We can come here with TIF_NEED_RESCHED already set from new task
1868 if (test_tsk_need_resched(curr
))
1871 /* Idle tasks are by definition preempted by non-idle tasks. */
1872 if (unlikely(curr
->policy
== SCHED_IDLE
) &&
1873 likely(p
->policy
!= SCHED_IDLE
))
1877 * Batch and idle tasks do not preempt non-idle tasks (their preemption
1878 * is driven by the tick):
1880 if (unlikely(p
->policy
!= SCHED_NORMAL
))
1884 if (!sched_feat(WAKEUP_PREEMPT
))
1887 update_curr(cfs_rq
);
1888 find_matching_se(&se
, &pse
);
1890 if (wakeup_preempt_entity(se
, pse
) == 1)
1898 * Only set the backward buddy when the current task is still
1899 * on the rq. This can happen when a wakeup gets interleaved
1900 * with schedule on the ->pre_schedule() or idle_balance()
1901 * point, either of which can * drop the rq lock.
1903 * Also, during early boot the idle thread is in the fair class,
1904 * for obvious reasons its a bad idea to schedule back to it.
1906 if (unlikely(!se
->on_rq
|| curr
== rq
->idle
))
1909 if (sched_feat(LAST_BUDDY
) && scale
&& entity_is_task(se
))
1913 static struct task_struct
*pick_next_task_fair(struct rq
*rq
)
1915 struct task_struct
*p
;
1916 struct cfs_rq
*cfs_rq
= &rq
->cfs
;
1917 struct sched_entity
*se
;
1919 if (!cfs_rq
->nr_running
)
1923 se
= pick_next_entity(cfs_rq
);
1924 set_next_entity(cfs_rq
, se
);
1925 cfs_rq
= group_cfs_rq(se
);
1929 hrtick_start_fair(rq
, p
);
1935 * Account for a descheduled task:
1937 static void put_prev_task_fair(struct rq
*rq
, struct task_struct
*prev
)
1939 struct sched_entity
*se
= &prev
->se
;
1940 struct cfs_rq
*cfs_rq
;
1942 for_each_sched_entity(se
) {
1943 cfs_rq
= cfs_rq_of(se
);
1944 put_prev_entity(cfs_rq
, se
);
1949 * sched_yield() is very simple
1951 * The magic of dealing with the ->skip buddy is in pick_next_entity.
1953 static void yield_task_fair(struct rq
*rq
)
1955 struct task_struct
*curr
= rq
->curr
;
1956 struct cfs_rq
*cfs_rq
= task_cfs_rq(curr
);
1957 struct sched_entity
*se
= &curr
->se
;
1960 * Are we the only task in the tree?
1962 if (unlikely(rq
->nr_running
== 1))
1965 clear_buddies(cfs_rq
, se
);
1967 if (curr
->policy
!= SCHED_BATCH
) {
1968 update_rq_clock(rq
);
1970 * Update run-time statistics of the 'current'.
1972 update_curr(cfs_rq
);
1978 static bool yield_to_task_fair(struct rq
*rq
, struct task_struct
*p
, bool preempt
)
1980 struct sched_entity
*se
= &p
->se
;
1985 /* Tell the scheduler that we'd really like pse to run next. */
1988 yield_task_fair(rq
);
1994 /**************************************************
1995 * Fair scheduling class load-balancing methods:
1999 * pull_task - move a task from a remote runqueue to the local runqueue.
2000 * Both runqueues must be locked.
2002 static void pull_task(struct rq
*src_rq
, struct task_struct
*p
,
2003 struct rq
*this_rq
, int this_cpu
)
2005 deactivate_task(src_rq
, p
, 0);
2006 set_task_cpu(p
, this_cpu
);
2007 activate_task(this_rq
, p
, 0);
2008 check_preempt_curr(this_rq
, p
, 0);
2012 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2015 int can_migrate_task(struct task_struct
*p
, struct rq
*rq
, int this_cpu
,
2016 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2019 int tsk_cache_hot
= 0;
2021 * We do not migrate tasks that are:
2022 * 1) running (obviously), or
2023 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2024 * 3) are cache-hot on their current CPU.
2026 if (!cpumask_test_cpu(this_cpu
, &p
->cpus_allowed
)) {
2027 schedstat_inc(p
, se
.statistics
.nr_failed_migrations_affine
);
2032 if (task_running(rq
, p
)) {
2033 schedstat_inc(p
, se
.statistics
.nr_failed_migrations_running
);
2038 * Aggressive migration if:
2039 * 1) task is cache cold, or
2040 * 2) too many balance attempts have failed.
2043 tsk_cache_hot
= task_hot(p
, rq
->clock_task
, sd
);
2044 if (!tsk_cache_hot
||
2045 sd
->nr_balance_failed
> sd
->cache_nice_tries
) {
2046 #ifdef CONFIG_SCHEDSTATS
2047 if (tsk_cache_hot
) {
2048 schedstat_inc(sd
, lb_hot_gained
[idle
]);
2049 schedstat_inc(p
, se
.statistics
.nr_forced_migrations
);
2055 if (tsk_cache_hot
) {
2056 schedstat_inc(p
, se
.statistics
.nr_failed_migrations_hot
);
2063 * move_one_task tries to move exactly one task from busiest to this_rq, as
2064 * part of active balancing operations within "domain".
2065 * Returns 1 if successful and 0 otherwise.
2067 * Called with both runqueues locked.
2070 move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2071 struct sched_domain
*sd
, enum cpu_idle_type idle
)
2073 struct task_struct
*p
, *n
;
2074 struct cfs_rq
*cfs_rq
;
2077 for_each_leaf_cfs_rq(busiest
, cfs_rq
) {
2078 list_for_each_entry_safe(p
, n
, &cfs_rq
->tasks
, se
.group_node
) {
2080 if (!can_migrate_task(p
, busiest
, this_cpu
,
2084 pull_task(busiest
, p
, this_rq
, this_cpu
);
2086 * Right now, this is only the second place pull_task()
2087 * is called, so we can safely collect pull_task()
2088 * stats here rather than inside pull_task().
2090 schedstat_inc(sd
, lb_gained
[idle
]);
2098 static unsigned long
2099 balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2100 unsigned long max_load_move
, struct sched_domain
*sd
,
2101 enum cpu_idle_type idle
, int *all_pinned
,
2102 int *this_best_prio
, struct cfs_rq
*busiest_cfs_rq
)
2104 int loops
= 0, pulled
= 0;
2105 long rem_load_move
= max_load_move
;
2106 struct task_struct
*p
, *n
;
2108 if (max_load_move
== 0)
2111 list_for_each_entry_safe(p
, n
, &busiest_cfs_rq
->tasks
, se
.group_node
) {
2112 if (loops
++ > sysctl_sched_nr_migrate
)
2115 if ((p
->se
.load
.weight
>> 1) > rem_load_move
||
2116 !can_migrate_task(p
, busiest
, this_cpu
, sd
, idle
,
2120 pull_task(busiest
, p
, this_rq
, this_cpu
);
2122 rem_load_move
-= p
->se
.load
.weight
;
2124 #ifdef CONFIG_PREEMPT
2126 * NEWIDLE balancing is a source of latency, so preemptible
2127 * kernels will stop after the first task is pulled to minimize
2128 * the critical section.
2130 if (idle
== CPU_NEWLY_IDLE
)
2135 * We only want to steal up to the prescribed amount of
2138 if (rem_load_move
<= 0)
2141 if (p
->prio
< *this_best_prio
)
2142 *this_best_prio
= p
->prio
;
2146 * Right now, this is one of only two places pull_task() is called,
2147 * so we can safely collect pull_task() stats here rather than
2148 * inside pull_task().
2150 schedstat_add(sd
, lb_gained
[idle
], pulled
);
2152 return max_load_move
- rem_load_move
;
2155 #ifdef CONFIG_FAIR_GROUP_SCHED
2157 * update tg->load_weight by folding this cpu's load_avg
2159 static int update_shares_cpu(struct task_group
*tg
, int cpu
)
2161 struct cfs_rq
*cfs_rq
;
2162 unsigned long flags
;
2169 cfs_rq
= tg
->cfs_rq
[cpu
];
2171 raw_spin_lock_irqsave(&rq
->lock
, flags
);
2173 update_rq_clock(rq
);
2174 update_cfs_load(cfs_rq
, 1);
2177 * We need to update shares after updating tg->load_weight in
2178 * order to adjust the weight of groups with long running tasks.
2180 update_cfs_shares(cfs_rq
);
2182 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
2187 static void update_shares(int cpu
)
2189 struct cfs_rq
*cfs_rq
;
2190 struct rq
*rq
= cpu_rq(cpu
);
2193 for_each_leaf_cfs_rq(rq
, cfs_rq
)
2194 update_shares_cpu(cfs_rq
->tg
, cpu
);
2198 static unsigned long
2199 load_balance_fair(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2200 unsigned long max_load_move
,
2201 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2202 int *all_pinned
, int *this_best_prio
)
2204 long rem_load_move
= max_load_move
;
2205 int busiest_cpu
= cpu_of(busiest
);
2206 struct task_group
*tg
;
2209 update_h_load(busiest_cpu
);
2211 list_for_each_entry_rcu(tg
, &task_groups
, list
) {
2212 struct cfs_rq
*busiest_cfs_rq
= tg
->cfs_rq
[busiest_cpu
];
2213 unsigned long busiest_h_load
= busiest_cfs_rq
->h_load
;
2214 unsigned long busiest_weight
= busiest_cfs_rq
->load
.weight
;
2215 u64 rem_load
, moved_load
;
2220 if (!busiest_cfs_rq
->task_weight
)
2223 rem_load
= (u64
)rem_load_move
* busiest_weight
;
2224 rem_load
= div_u64(rem_load
, busiest_h_load
+ 1);
2226 moved_load
= balance_tasks(this_rq
, this_cpu
, busiest
,
2227 rem_load
, sd
, idle
, all_pinned
, this_best_prio
,
2233 moved_load
*= busiest_h_load
;
2234 moved_load
= div_u64(moved_load
, busiest_weight
+ 1);
2236 rem_load_move
-= moved_load
;
2237 if (rem_load_move
< 0)
2242 return max_load_move
- rem_load_move
;
2245 static inline void update_shares(int cpu
)
2249 static unsigned long
2250 load_balance_fair(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2251 unsigned long max_load_move
,
2252 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2253 int *all_pinned
, int *this_best_prio
)
2255 return balance_tasks(this_rq
, this_cpu
, busiest
,
2256 max_load_move
, sd
, idle
, all_pinned
,
2257 this_best_prio
, &busiest
->cfs
);
2262 * move_tasks tries to move up to max_load_move weighted load from busiest to
2263 * this_rq, as part of a balancing operation within domain "sd".
2264 * Returns 1 if successful and 0 otherwise.
2266 * Called with both runqueues locked.
2268 static int move_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2269 unsigned long max_load_move
,
2270 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2273 unsigned long total_load_moved
= 0, load_moved
;
2274 int this_best_prio
= this_rq
->curr
->prio
;
2277 load_moved
= load_balance_fair(this_rq
, this_cpu
, busiest
,
2278 max_load_move
- total_load_moved
,
2279 sd
, idle
, all_pinned
, &this_best_prio
);
2281 total_load_moved
+= load_moved
;
2283 #ifdef CONFIG_PREEMPT
2285 * NEWIDLE balancing is a source of latency, so preemptible
2286 * kernels will stop after the first task is pulled to minimize
2287 * the critical section.
2289 if (idle
== CPU_NEWLY_IDLE
&& this_rq
->nr_running
)
2292 if (raw_spin_is_contended(&this_rq
->lock
) ||
2293 raw_spin_is_contended(&busiest
->lock
))
2296 } while (load_moved
&& max_load_move
> total_load_moved
);
2298 return total_load_moved
> 0;
2301 /********** Helpers for find_busiest_group ************************/
2303 * sd_lb_stats - Structure to store the statistics of a sched_domain
2304 * during load balancing.
2306 struct sd_lb_stats
{
2307 struct sched_group
*busiest
; /* Busiest group in this sd */
2308 struct sched_group
*this; /* Local group in this sd */
2309 unsigned long total_load
; /* Total load of all groups in sd */
2310 unsigned long total_pwr
; /* Total power of all groups in sd */
2311 unsigned long avg_load
; /* Average load across all groups in sd */
2313 /** Statistics of this group */
2314 unsigned long this_load
;
2315 unsigned long this_load_per_task
;
2316 unsigned long this_nr_running
;
2317 unsigned long this_has_capacity
;
2318 unsigned int this_idle_cpus
;
2320 /* Statistics of the busiest group */
2321 unsigned int busiest_idle_cpus
;
2322 unsigned long max_load
;
2323 unsigned long busiest_load_per_task
;
2324 unsigned long busiest_nr_running
;
2325 unsigned long busiest_group_capacity
;
2326 unsigned long busiest_has_capacity
;
2327 unsigned int busiest_group_weight
;
2329 int group_imb
; /* Is there imbalance in this sd */
2330 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2331 int power_savings_balance
; /* Is powersave balance needed for this sd */
2332 struct sched_group
*group_min
; /* Least loaded group in sd */
2333 struct sched_group
*group_leader
; /* Group which relieves group_min */
2334 unsigned long min_load_per_task
; /* load_per_task in group_min */
2335 unsigned long leader_nr_running
; /* Nr running of group_leader */
2336 unsigned long min_nr_running
; /* Nr running of group_min */
2341 * sg_lb_stats - stats of a sched_group required for load_balancing
2343 struct sg_lb_stats
{
2344 unsigned long avg_load
; /*Avg load across the CPUs of the group */
2345 unsigned long group_load
; /* Total load over the CPUs of the group */
2346 unsigned long sum_nr_running
; /* Nr tasks running in the group */
2347 unsigned long sum_weighted_load
; /* Weighted load of group's tasks */
2348 unsigned long group_capacity
;
2349 unsigned long idle_cpus
;
2350 unsigned long group_weight
;
2351 int group_imb
; /* Is there an imbalance in the group ? */
2352 int group_has_capacity
; /* Is there extra capacity in the group? */
2356 * group_first_cpu - Returns the first cpu in the cpumask of a sched_group.
2357 * @group: The group whose first cpu is to be returned.
2359 static inline unsigned int group_first_cpu(struct sched_group
*group
)
2361 return cpumask_first(sched_group_cpus(group
));
2365 * get_sd_load_idx - Obtain the load index for a given sched domain.
2366 * @sd: The sched_domain whose load_idx is to be obtained.
2367 * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
2369 static inline int get_sd_load_idx(struct sched_domain
*sd
,
2370 enum cpu_idle_type idle
)
2376 load_idx
= sd
->busy_idx
;
2379 case CPU_NEWLY_IDLE
:
2380 load_idx
= sd
->newidle_idx
;
2383 load_idx
= sd
->idle_idx
;
2391 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2393 * init_sd_power_savings_stats - Initialize power savings statistics for
2394 * the given sched_domain, during load balancing.
2396 * @sd: Sched domain whose power-savings statistics are to be initialized.
2397 * @sds: Variable containing the statistics for sd.
2398 * @idle: Idle status of the CPU at which we're performing load-balancing.
2400 static inline void init_sd_power_savings_stats(struct sched_domain
*sd
,
2401 struct sd_lb_stats
*sds
, enum cpu_idle_type idle
)
2404 * Busy processors will not participate in power savings
2407 if (idle
== CPU_NOT_IDLE
|| !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2408 sds
->power_savings_balance
= 0;
2410 sds
->power_savings_balance
= 1;
2411 sds
->min_nr_running
= ULONG_MAX
;
2412 sds
->leader_nr_running
= 0;
2417 * update_sd_power_savings_stats - Update the power saving stats for a
2418 * sched_domain while performing load balancing.
2420 * @group: sched_group belonging to the sched_domain under consideration.
2421 * @sds: Variable containing the statistics of the sched_domain
2422 * @local_group: Does group contain the CPU for which we're performing
2424 * @sgs: Variable containing the statistics of the group.
2426 static inline void update_sd_power_savings_stats(struct sched_group
*group
,
2427 struct sd_lb_stats
*sds
, int local_group
, struct sg_lb_stats
*sgs
)
2430 if (!sds
->power_savings_balance
)
2434 * If the local group is idle or completely loaded
2435 * no need to do power savings balance at this domain
2437 if (local_group
&& (sds
->this_nr_running
>= sgs
->group_capacity
||
2438 !sds
->this_nr_running
))
2439 sds
->power_savings_balance
= 0;
2442 * If a group is already running at full capacity or idle,
2443 * don't include that group in power savings calculations
2445 if (!sds
->power_savings_balance
||
2446 sgs
->sum_nr_running
>= sgs
->group_capacity
||
2447 !sgs
->sum_nr_running
)
2451 * Calculate the group which has the least non-idle load.
2452 * This is the group from where we need to pick up the load
2455 if ((sgs
->sum_nr_running
< sds
->min_nr_running
) ||
2456 (sgs
->sum_nr_running
== sds
->min_nr_running
&&
2457 group_first_cpu(group
) > group_first_cpu(sds
->group_min
))) {
2458 sds
->group_min
= group
;
2459 sds
->min_nr_running
= sgs
->sum_nr_running
;
2460 sds
->min_load_per_task
= sgs
->sum_weighted_load
/
2461 sgs
->sum_nr_running
;
2465 * Calculate the group which is almost near its
2466 * capacity but still has some space to pick up some load
2467 * from other group and save more power
2469 if (sgs
->sum_nr_running
+ 1 > sgs
->group_capacity
)
2472 if (sgs
->sum_nr_running
> sds
->leader_nr_running
||
2473 (sgs
->sum_nr_running
== sds
->leader_nr_running
&&
2474 group_first_cpu(group
) < group_first_cpu(sds
->group_leader
))) {
2475 sds
->group_leader
= group
;
2476 sds
->leader_nr_running
= sgs
->sum_nr_running
;
2481 * check_power_save_busiest_group - see if there is potential for some power-savings balance
2482 * @sds: Variable containing the statistics of the sched_domain
2483 * under consideration.
2484 * @this_cpu: Cpu at which we're currently performing load-balancing.
2485 * @imbalance: Variable to store the imbalance.
2488 * Check if we have potential to perform some power-savings balance.
2489 * If yes, set the busiest group to be the least loaded group in the
2490 * sched_domain, so that it's CPUs can be put to idle.
2492 * Returns 1 if there is potential to perform power-savings balance.
2495 static inline int check_power_save_busiest_group(struct sd_lb_stats
*sds
,
2496 int this_cpu
, unsigned long *imbalance
)
2498 if (!sds
->power_savings_balance
)
2501 if (sds
->this != sds
->group_leader
||
2502 sds
->group_leader
== sds
->group_min
)
2505 *imbalance
= sds
->min_load_per_task
;
2506 sds
->busiest
= sds
->group_min
;
2511 #else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
2512 static inline void init_sd_power_savings_stats(struct sched_domain
*sd
,
2513 struct sd_lb_stats
*sds
, enum cpu_idle_type idle
)
2518 static inline void update_sd_power_savings_stats(struct sched_group
*group
,
2519 struct sd_lb_stats
*sds
, int local_group
, struct sg_lb_stats
*sgs
)
2524 static inline int check_power_save_busiest_group(struct sd_lb_stats
*sds
,
2525 int this_cpu
, unsigned long *imbalance
)
2529 #endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
2532 unsigned long default_scale_freq_power(struct sched_domain
*sd
, int cpu
)
2534 return SCHED_LOAD_SCALE
;
2537 unsigned long __weak
arch_scale_freq_power(struct sched_domain
*sd
, int cpu
)
2539 return default_scale_freq_power(sd
, cpu
);
2542 unsigned long default_scale_smt_power(struct sched_domain
*sd
, int cpu
)
2544 unsigned long weight
= sd
->span_weight
;
2545 unsigned long smt_gain
= sd
->smt_gain
;
2552 unsigned long __weak
arch_scale_smt_power(struct sched_domain
*sd
, int cpu
)
2554 return default_scale_smt_power(sd
, cpu
);
2557 unsigned long scale_rt_power(int cpu
)
2559 struct rq
*rq
= cpu_rq(cpu
);
2560 u64 total
, available
;
2562 total
= sched_avg_period() + (rq
->clock
- rq
->age_stamp
);
2564 if (unlikely(total
< rq
->rt_avg
)) {
2565 /* Ensures that power won't end up being negative */
2568 available
= total
- rq
->rt_avg
;
2571 if (unlikely((s64
)total
< SCHED_LOAD_SCALE
))
2572 total
= SCHED_LOAD_SCALE
;
2574 total
>>= SCHED_LOAD_SHIFT
;
2576 return div_u64(available
, total
);
2579 static void update_cpu_power(struct sched_domain
*sd
, int cpu
)
2581 unsigned long weight
= sd
->span_weight
;
2582 unsigned long power
= SCHED_LOAD_SCALE
;
2583 struct sched_group
*sdg
= sd
->groups
;
2585 if ((sd
->flags
& SD_SHARE_CPUPOWER
) && weight
> 1) {
2586 if (sched_feat(ARCH_POWER
))
2587 power
*= arch_scale_smt_power(sd
, cpu
);
2589 power
*= default_scale_smt_power(sd
, cpu
);
2591 power
>>= SCHED_LOAD_SHIFT
;
2594 sdg
->cpu_power_orig
= power
;
2596 if (sched_feat(ARCH_POWER
))
2597 power
*= arch_scale_freq_power(sd
, cpu
);
2599 power
*= default_scale_freq_power(sd
, cpu
);
2601 power
>>= SCHED_LOAD_SHIFT
;
2603 power
*= scale_rt_power(cpu
);
2604 power
>>= SCHED_LOAD_SHIFT
;
2609 cpu_rq(cpu
)->cpu_power
= power
;
2610 sdg
->cpu_power
= power
;
2613 static void update_group_power(struct sched_domain
*sd
, int cpu
)
2615 struct sched_domain
*child
= sd
->child
;
2616 struct sched_group
*group
, *sdg
= sd
->groups
;
2617 unsigned long power
;
2620 update_cpu_power(sd
, cpu
);
2626 group
= child
->groups
;
2628 power
+= group
->cpu_power
;
2629 group
= group
->next
;
2630 } while (group
!= child
->groups
);
2632 sdg
->cpu_power
= power
;
2636 * Try and fix up capacity for tiny siblings, this is needed when
2637 * things like SD_ASYM_PACKING need f_b_g to select another sibling
2638 * which on its own isn't powerful enough.
2640 * See update_sd_pick_busiest() and check_asym_packing().
2643 fix_small_capacity(struct sched_domain
*sd
, struct sched_group
*group
)
2646 * Only siblings can have significantly less than SCHED_LOAD_SCALE
2648 if (sd
->level
!= SD_LV_SIBLING
)
2652 * If ~90% of the cpu_power is still there, we're good.
2654 if (group
->cpu_power
* 32 > group
->cpu_power_orig
* 29)
2661 * update_sg_lb_stats - Update sched_group's statistics for load balancing.
2662 * @sd: The sched_domain whose statistics are to be updated.
2663 * @group: sched_group whose statistics are to be updated.
2664 * @this_cpu: Cpu for which load balance is currently performed.
2665 * @idle: Idle status of this_cpu
2666 * @load_idx: Load index of sched_domain of this_cpu for load calc.
2667 * @local_group: Does group contain this_cpu.
2668 * @cpus: Set of cpus considered for load balancing.
2669 * @balance: Should we balance.
2670 * @sgs: variable to hold the statistics for this group.
2672 static inline void update_sg_lb_stats(struct sched_domain
*sd
,
2673 struct sched_group
*group
, int this_cpu
,
2674 enum cpu_idle_type idle
, int load_idx
,
2675 int local_group
, const struct cpumask
*cpus
,
2676 int *balance
, struct sg_lb_stats
*sgs
)
2678 unsigned long load
, max_cpu_load
, min_cpu_load
, max_nr_running
;
2680 unsigned int balance_cpu
= -1, first_idle_cpu
= 0;
2681 unsigned long avg_load_per_task
= 0;
2684 balance_cpu
= group_first_cpu(group
);
2686 /* Tally up the load of all CPUs in the group */
2688 min_cpu_load
= ~0UL;
2691 for_each_cpu_and(i
, sched_group_cpus(group
), cpus
) {
2692 struct rq
*rq
= cpu_rq(i
);
2694 /* Bias balancing toward cpus of our domain */
2696 if (idle_cpu(i
) && !first_idle_cpu
) {
2701 load
= target_load(i
, load_idx
);
2703 load
= source_load(i
, load_idx
);
2704 if (load
> max_cpu_load
) {
2705 max_cpu_load
= load
;
2706 max_nr_running
= rq
->nr_running
;
2708 if (min_cpu_load
> load
)
2709 min_cpu_load
= load
;
2712 sgs
->group_load
+= load
;
2713 sgs
->sum_nr_running
+= rq
->nr_running
;
2714 sgs
->sum_weighted_load
+= weighted_cpuload(i
);
2720 * First idle cpu or the first cpu(busiest) in this sched group
2721 * is eligible for doing load balancing at this and above
2722 * domains. In the newly idle case, we will allow all the cpu's
2723 * to do the newly idle load balance.
2725 if (idle
!= CPU_NEWLY_IDLE
&& local_group
) {
2726 if (balance_cpu
!= this_cpu
) {
2730 update_group_power(sd
, this_cpu
);
2733 /* Adjust by relative CPU power of the group */
2734 sgs
->avg_load
= (sgs
->group_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
2737 * Consider the group unbalanced when the imbalance is larger
2738 * than the average weight of a task.
2740 * APZ: with cgroup the avg task weight can vary wildly and
2741 * might not be a suitable number - should we keep a
2742 * normalized nr_running number somewhere that negates
2745 if (sgs
->sum_nr_running
)
2746 avg_load_per_task
= sgs
->sum_weighted_load
/ sgs
->sum_nr_running
;
2748 if ((max_cpu_load
- min_cpu_load
) >= avg_load_per_task
&& max_nr_running
> 1)
2751 sgs
->group_capacity
= DIV_ROUND_CLOSEST(group
->cpu_power
, SCHED_LOAD_SCALE
);
2752 if (!sgs
->group_capacity
)
2753 sgs
->group_capacity
= fix_small_capacity(sd
, group
);
2754 sgs
->group_weight
= group
->group_weight
;
2756 if (sgs
->group_capacity
> sgs
->sum_nr_running
)
2757 sgs
->group_has_capacity
= 1;
2761 * update_sd_pick_busiest - return 1 on busiest group
2762 * @sd: sched_domain whose statistics are to be checked
2763 * @sds: sched_domain statistics
2764 * @sg: sched_group candidate to be checked for being the busiest
2765 * @sgs: sched_group statistics
2766 * @this_cpu: the current cpu
2768 * Determine if @sg is a busier group than the previously selected
2771 static bool update_sd_pick_busiest(struct sched_domain
*sd
,
2772 struct sd_lb_stats
*sds
,
2773 struct sched_group
*sg
,
2774 struct sg_lb_stats
*sgs
,
2777 if (sgs
->avg_load
<= sds
->max_load
)
2780 if (sgs
->sum_nr_running
> sgs
->group_capacity
)
2787 * ASYM_PACKING needs to move all the work to the lowest
2788 * numbered CPUs in the group, therefore mark all groups
2789 * higher than ourself as busy.
2791 if ((sd
->flags
& SD_ASYM_PACKING
) && sgs
->sum_nr_running
&&
2792 this_cpu
< group_first_cpu(sg
)) {
2796 if (group_first_cpu(sds
->busiest
) > group_first_cpu(sg
))
2804 * update_sd_lb_stats - Update sched_group's statistics for load balancing.
2805 * @sd: sched_domain whose statistics are to be updated.
2806 * @this_cpu: Cpu for which load balance is currently performed.
2807 * @idle: Idle status of this_cpu
2808 * @cpus: Set of cpus considered for load balancing.
2809 * @balance: Should we balance.
2810 * @sds: variable to hold the statistics for this sched_domain.
2812 static inline void update_sd_lb_stats(struct sched_domain
*sd
, int this_cpu
,
2813 enum cpu_idle_type idle
, const struct cpumask
*cpus
,
2814 int *balance
, struct sd_lb_stats
*sds
)
2816 struct sched_domain
*child
= sd
->child
;
2817 struct sched_group
*sg
= sd
->groups
;
2818 struct sg_lb_stats sgs
;
2819 int load_idx
, prefer_sibling
= 0;
2821 if (child
&& child
->flags
& SD_PREFER_SIBLING
)
2824 init_sd_power_savings_stats(sd
, sds
, idle
);
2825 load_idx
= get_sd_load_idx(sd
, idle
);
2830 local_group
= cpumask_test_cpu(this_cpu
, sched_group_cpus(sg
));
2831 memset(&sgs
, 0, sizeof(sgs
));
2832 update_sg_lb_stats(sd
, sg
, this_cpu
, idle
, load_idx
,
2833 local_group
, cpus
, balance
, &sgs
);
2835 if (local_group
&& !(*balance
))
2838 sds
->total_load
+= sgs
.group_load
;
2839 sds
->total_pwr
+= sg
->cpu_power
;
2842 * In case the child domain prefers tasks go to siblings
2843 * first, lower the sg capacity to one so that we'll try
2844 * and move all the excess tasks away. We lower the capacity
2845 * of a group only if the local group has the capacity to fit
2846 * these excess tasks, i.e. nr_running < group_capacity. The
2847 * extra check prevents the case where you always pull from the
2848 * heaviest group when it is already under-utilized (possible
2849 * with a large weight task outweighs the tasks on the system).
2851 if (prefer_sibling
&& !local_group
&& sds
->this_has_capacity
)
2852 sgs
.group_capacity
= min(sgs
.group_capacity
, 1UL);
2855 sds
->this_load
= sgs
.avg_load
;
2857 sds
->this_nr_running
= sgs
.sum_nr_running
;
2858 sds
->this_load_per_task
= sgs
.sum_weighted_load
;
2859 sds
->this_has_capacity
= sgs
.group_has_capacity
;
2860 sds
->this_idle_cpus
= sgs
.idle_cpus
;
2861 } else if (update_sd_pick_busiest(sd
, sds
, sg
, &sgs
, this_cpu
)) {
2862 sds
->max_load
= sgs
.avg_load
;
2864 sds
->busiest_nr_running
= sgs
.sum_nr_running
;
2865 sds
->busiest_idle_cpus
= sgs
.idle_cpus
;
2866 sds
->busiest_group_capacity
= sgs
.group_capacity
;
2867 sds
->busiest_load_per_task
= sgs
.sum_weighted_load
;
2868 sds
->busiest_has_capacity
= sgs
.group_has_capacity
;
2869 sds
->busiest_group_weight
= sgs
.group_weight
;
2870 sds
->group_imb
= sgs
.group_imb
;
2873 update_sd_power_savings_stats(sg
, sds
, local_group
, &sgs
);
2875 } while (sg
!= sd
->groups
);
2878 int __weak
arch_sd_sibling_asym_packing(void)
2880 return 0*SD_ASYM_PACKING
;
2884 * check_asym_packing - Check to see if the group is packed into the
2887 * This is primarily intended to used at the sibling level. Some
2888 * cores like POWER7 prefer to use lower numbered SMT threads. In the
2889 * case of POWER7, it can move to lower SMT modes only when higher
2890 * threads are idle. When in lower SMT modes, the threads will
2891 * perform better since they share less core resources. Hence when we
2892 * have idle threads, we want them to be the higher ones.
2894 * This packing function is run on idle threads. It checks to see if
2895 * the busiest CPU in this domain (core in the P7 case) has a higher
2896 * CPU number than the packing function is being run on. Here we are
2897 * assuming lower CPU number will be equivalent to lower a SMT thread
2900 * Returns 1 when packing is required and a task should be moved to
2901 * this CPU. The amount of the imbalance is returned in *imbalance.
2903 * @sd: The sched_domain whose packing is to be checked.
2904 * @sds: Statistics of the sched_domain which is to be packed
2905 * @this_cpu: The cpu at whose sched_domain we're performing load-balance.
2906 * @imbalance: returns amount of imbalanced due to packing.
2908 static int check_asym_packing(struct sched_domain
*sd
,
2909 struct sd_lb_stats
*sds
,
2910 int this_cpu
, unsigned long *imbalance
)
2914 if (!(sd
->flags
& SD_ASYM_PACKING
))
2920 busiest_cpu
= group_first_cpu(sds
->busiest
);
2921 if (this_cpu
> busiest_cpu
)
2924 *imbalance
= DIV_ROUND_CLOSEST(sds
->max_load
* sds
->busiest
->cpu_power
,
2930 * fix_small_imbalance - Calculate the minor imbalance that exists
2931 * amongst the groups of a sched_domain, during
2933 * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
2934 * @this_cpu: The cpu at whose sched_domain we're performing load-balance.
2935 * @imbalance: Variable to store the imbalance.
2937 static inline void fix_small_imbalance(struct sd_lb_stats
*sds
,
2938 int this_cpu
, unsigned long *imbalance
)
2940 unsigned long tmp
, pwr_now
= 0, pwr_move
= 0;
2941 unsigned int imbn
= 2;
2942 unsigned long scaled_busy_load_per_task
;
2944 if (sds
->this_nr_running
) {
2945 sds
->this_load_per_task
/= sds
->this_nr_running
;
2946 if (sds
->busiest_load_per_task
>
2947 sds
->this_load_per_task
)
2950 sds
->this_load_per_task
=
2951 cpu_avg_load_per_task(this_cpu
);
2953 scaled_busy_load_per_task
= sds
->busiest_load_per_task
2955 scaled_busy_load_per_task
/= sds
->busiest
->cpu_power
;
2957 if (sds
->max_load
- sds
->this_load
+ scaled_busy_load_per_task
>=
2958 (scaled_busy_load_per_task
* imbn
)) {
2959 *imbalance
= sds
->busiest_load_per_task
;
2964 * OK, we don't have enough imbalance to justify moving tasks,
2965 * however we may be able to increase total CPU power used by
2969 pwr_now
+= sds
->busiest
->cpu_power
*
2970 min(sds
->busiest_load_per_task
, sds
->max_load
);
2971 pwr_now
+= sds
->this->cpu_power
*
2972 min(sds
->this_load_per_task
, sds
->this_load
);
2973 pwr_now
/= SCHED_LOAD_SCALE
;
2975 /* Amount of load we'd subtract */
2976 tmp
= (sds
->busiest_load_per_task
* SCHED_LOAD_SCALE
) /
2977 sds
->busiest
->cpu_power
;
2978 if (sds
->max_load
> tmp
)
2979 pwr_move
+= sds
->busiest
->cpu_power
*
2980 min(sds
->busiest_load_per_task
, sds
->max_load
- tmp
);
2982 /* Amount of load we'd add */
2983 if (sds
->max_load
* sds
->busiest
->cpu_power
<
2984 sds
->busiest_load_per_task
* SCHED_LOAD_SCALE
)
2985 tmp
= (sds
->max_load
* sds
->busiest
->cpu_power
) /
2986 sds
->this->cpu_power
;
2988 tmp
= (sds
->busiest_load_per_task
* SCHED_LOAD_SCALE
) /
2989 sds
->this->cpu_power
;
2990 pwr_move
+= sds
->this->cpu_power
*
2991 min(sds
->this_load_per_task
, sds
->this_load
+ tmp
);
2992 pwr_move
/= SCHED_LOAD_SCALE
;
2994 /* Move if we gain throughput */
2995 if (pwr_move
> pwr_now
)
2996 *imbalance
= sds
->busiest_load_per_task
;
3000 * calculate_imbalance - Calculate the amount of imbalance present within the
3001 * groups of a given sched_domain during load balance.
3002 * @sds: statistics of the sched_domain whose imbalance is to be calculated.
3003 * @this_cpu: Cpu for which currently load balance is being performed.
3004 * @imbalance: The variable to store the imbalance.
3006 static inline void calculate_imbalance(struct sd_lb_stats
*sds
, int this_cpu
,
3007 unsigned long *imbalance
)
3009 unsigned long max_pull
, load_above_capacity
= ~0UL;
3011 sds
->busiest_load_per_task
/= sds
->busiest_nr_running
;
3012 if (sds
->group_imb
) {
3013 sds
->busiest_load_per_task
=
3014 min(sds
->busiest_load_per_task
, sds
->avg_load
);
3018 * In the presence of smp nice balancing, certain scenarios can have
3019 * max load less than avg load(as we skip the groups at or below
3020 * its cpu_power, while calculating max_load..)
3022 if (sds
->max_load
< sds
->avg_load
) {
3024 return fix_small_imbalance(sds
, this_cpu
, imbalance
);
3027 if (!sds
->group_imb
) {
3029 * Don't want to pull so many tasks that a group would go idle.
3031 load_above_capacity
= (sds
->busiest_nr_running
-
3032 sds
->busiest_group_capacity
);
3034 load_above_capacity
*= (SCHED_LOAD_SCALE
* SCHED_LOAD_SCALE
);
3036 load_above_capacity
/= sds
->busiest
->cpu_power
;
3040 * We're trying to get all the cpus to the average_load, so we don't
3041 * want to push ourselves above the average load, nor do we wish to
3042 * reduce the max loaded cpu below the average load. At the same time,
3043 * we also don't want to reduce the group load below the group capacity
3044 * (so that we can implement power-savings policies etc). Thus we look
3045 * for the minimum possible imbalance.
3046 * Be careful of negative numbers as they'll appear as very large values
3047 * with unsigned longs.
3049 max_pull
= min(sds
->max_load
- sds
->avg_load
, load_above_capacity
);
3051 /* How much load to actually move to equalise the imbalance */
3052 *imbalance
= min(max_pull
* sds
->busiest
->cpu_power
,
3053 (sds
->avg_load
- sds
->this_load
) * sds
->this->cpu_power
)
3057 * if *imbalance is less than the average load per runnable task
3058 * there is no guarantee that any tasks will be moved so we'll have
3059 * a think about bumping its value to force at least one task to be
3062 if (*imbalance
< sds
->busiest_load_per_task
)
3063 return fix_small_imbalance(sds
, this_cpu
, imbalance
);
3067 /******* find_busiest_group() helpers end here *********************/
3070 * find_busiest_group - Returns the busiest group within the sched_domain
3071 * if there is an imbalance. If there isn't an imbalance, and
3072 * the user has opted for power-savings, it returns a group whose
3073 * CPUs can be put to idle by rebalancing those tasks elsewhere, if
3074 * such a group exists.
3076 * Also calculates the amount of weighted load which should be moved
3077 * to restore balance.
3079 * @sd: The sched_domain whose busiest group is to be returned.
3080 * @this_cpu: The cpu for which load balancing is currently being performed.
3081 * @imbalance: Variable which stores amount of weighted load which should
3082 * be moved to restore balance/put a group to idle.
3083 * @idle: The idle status of this_cpu.
3084 * @cpus: The set of CPUs under consideration for load-balancing.
3085 * @balance: Pointer to a variable indicating if this_cpu
3086 * is the appropriate cpu to perform load balancing at this_level.
3088 * Returns: - the busiest group if imbalance exists.
3089 * - If no imbalance and user has opted for power-savings balance,
3090 * return the least loaded group whose CPUs can be
3091 * put to idle by rebalancing its tasks onto our group.
3093 static struct sched_group
*
3094 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
3095 unsigned long *imbalance
, enum cpu_idle_type idle
,
3096 const struct cpumask
*cpus
, int *balance
)
3098 struct sd_lb_stats sds
;
3100 memset(&sds
, 0, sizeof(sds
));
3103 * Compute the various statistics relavent for load balancing at
3106 update_sd_lb_stats(sd
, this_cpu
, idle
, cpus
, balance
, &sds
);
3109 * this_cpu is not the appropriate cpu to perform load balancing at
3115 if ((idle
== CPU_IDLE
|| idle
== CPU_NEWLY_IDLE
) &&
3116 check_asym_packing(sd
, &sds
, this_cpu
, imbalance
))
3119 /* There is no busy sibling group to pull tasks from */
3120 if (!sds
.busiest
|| sds
.busiest_nr_running
== 0)
3123 sds
.avg_load
= (SCHED_LOAD_SCALE
* sds
.total_load
) / sds
.total_pwr
;
3126 * If the busiest group is imbalanced the below checks don't
3127 * work because they assumes all things are equal, which typically
3128 * isn't true due to cpus_allowed constraints and the like.
3133 /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
3134 if (idle
== CPU_NEWLY_IDLE
&& sds
.this_has_capacity
&&
3135 !sds
.busiest_has_capacity
)
3139 * If the local group is more busy than the selected busiest group
3140 * don't try and pull any tasks.
3142 if (sds
.this_load
>= sds
.max_load
)
3146 * Don't pull any tasks if this group is already above the domain
3149 if (sds
.this_load
>= sds
.avg_load
)
3152 if (idle
== CPU_IDLE
) {
3154 * This cpu is idle. If the busiest group load doesn't
3155 * have more tasks than the number of available cpu's and
3156 * there is no imbalance between this and busiest group
3157 * wrt to idle cpu's, it is balanced.
3159 if ((sds
.this_idle_cpus
<= sds
.busiest_idle_cpus
+ 1) &&
3160 sds
.busiest_nr_running
<= sds
.busiest_group_weight
)
3164 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
3165 * imbalance_pct to be conservative.
3167 if (100 * sds
.max_load
<= sd
->imbalance_pct
* sds
.this_load
)
3172 /* Looks like there is an imbalance. Compute it */
3173 calculate_imbalance(&sds
, this_cpu
, imbalance
);
3178 * There is no obvious imbalance. But check if we can do some balancing
3181 if (check_power_save_busiest_group(&sds
, this_cpu
, imbalance
))
3189 * find_busiest_queue - find the busiest runqueue among the cpus in group.
3192 find_busiest_queue(struct sched_domain
*sd
, struct sched_group
*group
,
3193 enum cpu_idle_type idle
, unsigned long imbalance
,
3194 const struct cpumask
*cpus
)
3196 struct rq
*busiest
= NULL
, *rq
;
3197 unsigned long max_load
= 0;
3200 for_each_cpu(i
, sched_group_cpus(group
)) {
3201 unsigned long power
= power_of(i
);
3202 unsigned long capacity
= DIV_ROUND_CLOSEST(power
, SCHED_LOAD_SCALE
);
3206 capacity
= fix_small_capacity(sd
, group
);
3208 if (!cpumask_test_cpu(i
, cpus
))
3212 wl
= weighted_cpuload(i
);
3215 * When comparing with imbalance, use weighted_cpuload()
3216 * which is not scaled with the cpu power.
3218 if (capacity
&& rq
->nr_running
== 1 && wl
> imbalance
)
3222 * For the load comparisons with the other cpu's, consider
3223 * the weighted_cpuload() scaled with the cpu power, so that
3224 * the load can be moved away from the cpu that is potentially
3225 * running at a lower capacity.
3227 wl
= (wl
* SCHED_LOAD_SCALE
) / power
;
3229 if (wl
> max_load
) {
3239 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
3240 * so long as it is large enough.
3242 #define MAX_PINNED_INTERVAL 512
3244 /* Working cpumask for load_balance and load_balance_newidle. */
3245 static DEFINE_PER_CPU(cpumask_var_t
, load_balance_tmpmask
);
3247 static int need_active_balance(struct sched_domain
*sd
, int idle
,
3248 int busiest_cpu
, int this_cpu
)
3250 if (idle
== CPU_NEWLY_IDLE
) {
3253 * ASYM_PACKING needs to force migrate tasks from busy but
3254 * higher numbered CPUs in order to pack all tasks in the
3255 * lowest numbered CPUs.
3257 if ((sd
->flags
& SD_ASYM_PACKING
) && busiest_cpu
> this_cpu
)
3261 * The only task running in a non-idle cpu can be moved to this
3262 * cpu in an attempt to completely freeup the other CPU
3265 * The package power saving logic comes from
3266 * find_busiest_group(). If there are no imbalance, then
3267 * f_b_g() will return NULL. However when sched_mc={1,2} then
3268 * f_b_g() will select a group from which a running task may be
3269 * pulled to this cpu in order to make the other package idle.
3270 * If there is no opportunity to make a package idle and if
3271 * there are no imbalance, then f_b_g() will return NULL and no
3272 * action will be taken in load_balance_newidle().
3274 * Under normal task pull operation due to imbalance, there
3275 * will be more than one task in the source run queue and
3276 * move_tasks() will succeed. ld_moved will be true and this
3277 * active balance code will not be triggered.
3279 if (sched_mc_power_savings
< POWERSAVINGS_BALANCE_WAKEUP
)
3283 return unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2);
3286 static int active_load_balance_cpu_stop(void *data
);
3289 * Check this_cpu to ensure it is balanced within domain. Attempt to move
3290 * tasks if there is an imbalance.
3292 static int load_balance(int this_cpu
, struct rq
*this_rq
,
3293 struct sched_domain
*sd
, enum cpu_idle_type idle
,
3296 int ld_moved
, all_pinned
= 0, active_balance
= 0;
3297 struct sched_group
*group
;
3298 unsigned long imbalance
;
3300 unsigned long flags
;
3301 struct cpumask
*cpus
= __get_cpu_var(load_balance_tmpmask
);
3303 cpumask_copy(cpus
, cpu_active_mask
);
3305 schedstat_inc(sd
, lb_count
[idle
]);
3308 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
,
3315 schedstat_inc(sd
, lb_nobusyg
[idle
]);
3319 busiest
= find_busiest_queue(sd
, group
, idle
, imbalance
, cpus
);
3321 schedstat_inc(sd
, lb_nobusyq
[idle
]);
3325 BUG_ON(busiest
== this_rq
);
3327 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
3330 if (busiest
->nr_running
> 1) {
3332 * Attempt to move tasks. If find_busiest_group has found
3333 * an imbalance but busiest->nr_running <= 1, the group is
3334 * still unbalanced. ld_moved simply stays zero, so it is
3335 * correctly treated as an imbalance.
3338 local_irq_save(flags
);
3339 double_rq_lock(this_rq
, busiest
);
3340 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
3341 imbalance
, sd
, idle
, &all_pinned
);
3342 double_rq_unlock(this_rq
, busiest
);
3343 local_irq_restore(flags
);
3346 * some other cpu did the load balance for us.
3348 if (ld_moved
&& this_cpu
!= smp_processor_id())
3349 resched_cpu(this_cpu
);
3351 /* All tasks on this runqueue were pinned by CPU affinity */
3352 if (unlikely(all_pinned
)) {
3353 cpumask_clear_cpu(cpu_of(busiest
), cpus
);
3354 if (!cpumask_empty(cpus
))
3361 schedstat_inc(sd
, lb_failed
[idle
]);
3363 * Increment the failure counter only on periodic balance.
3364 * We do not want newidle balance, which can be very
3365 * frequent, pollute the failure counter causing
3366 * excessive cache_hot migrations and active balances.
3368 if (idle
!= CPU_NEWLY_IDLE
)
3369 sd
->nr_balance_failed
++;
3371 if (need_active_balance(sd
, idle
, cpu_of(busiest
), this_cpu
)) {
3372 raw_spin_lock_irqsave(&busiest
->lock
, flags
);
3374 /* don't kick the active_load_balance_cpu_stop,
3375 * if the curr task on busiest cpu can't be
3378 if (!cpumask_test_cpu(this_cpu
,
3379 &busiest
->curr
->cpus_allowed
)) {
3380 raw_spin_unlock_irqrestore(&busiest
->lock
,
3383 goto out_one_pinned
;
3387 * ->active_balance synchronizes accesses to
3388 * ->active_balance_work. Once set, it's cleared
3389 * only after active load balance is finished.
3391 if (!busiest
->active_balance
) {
3392 busiest
->active_balance
= 1;
3393 busiest
->push_cpu
= this_cpu
;
3396 raw_spin_unlock_irqrestore(&busiest
->lock
, flags
);
3399 stop_one_cpu_nowait(cpu_of(busiest
),
3400 active_load_balance_cpu_stop
, busiest
,
3401 &busiest
->active_balance_work
);
3404 * We've kicked active balancing, reset the failure
3407 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
3410 sd
->nr_balance_failed
= 0;
3412 if (likely(!active_balance
)) {
3413 /* We were unbalanced, so reset the balancing interval */
3414 sd
->balance_interval
= sd
->min_interval
;
3417 * If we've begun active balancing, start to back off. This
3418 * case may not be covered by the all_pinned logic if there
3419 * is only 1 task on the busy runqueue (because we don't call
3422 if (sd
->balance_interval
< sd
->max_interval
)
3423 sd
->balance_interval
*= 2;
3429 schedstat_inc(sd
, lb_balanced
[idle
]);
3431 sd
->nr_balance_failed
= 0;
3434 /* tune up the balancing interval */
3435 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
3436 (sd
->balance_interval
< sd
->max_interval
))
3437 sd
->balance_interval
*= 2;
3445 * idle_balance is called by schedule() if this_cpu is about to become
3446 * idle. Attempts to pull tasks from other CPUs.
3448 static void idle_balance(int this_cpu
, struct rq
*this_rq
)
3450 struct sched_domain
*sd
;
3451 int pulled_task
= 0;
3452 unsigned long next_balance
= jiffies
+ HZ
;
3454 this_rq
->idle_stamp
= this_rq
->clock
;
3456 if (this_rq
->avg_idle
< sysctl_sched_migration_cost
)
3460 * Drop the rq->lock, but keep IRQ/preempt disabled.
3462 raw_spin_unlock(&this_rq
->lock
);
3464 update_shares(this_cpu
);
3465 for_each_domain(this_cpu
, sd
) {
3466 unsigned long interval
;
3469 if (!(sd
->flags
& SD_LOAD_BALANCE
))
3472 if (sd
->flags
& SD_BALANCE_NEWIDLE
) {
3473 /* If we've pulled tasks over stop searching: */
3474 pulled_task
= load_balance(this_cpu
, this_rq
,
3475 sd
, CPU_NEWLY_IDLE
, &balance
);
3478 interval
= msecs_to_jiffies(sd
->balance_interval
);
3479 if (time_after(next_balance
, sd
->last_balance
+ interval
))
3480 next_balance
= sd
->last_balance
+ interval
;
3482 this_rq
->idle_stamp
= 0;
3487 raw_spin_lock(&this_rq
->lock
);
3489 if (pulled_task
|| time_after(jiffies
, this_rq
->next_balance
)) {
3491 * We are going idle. next_balance may be set based on
3492 * a busy processor. So reset next_balance.
3494 this_rq
->next_balance
= next_balance
;
3499 * active_load_balance_cpu_stop is run by cpu stopper. It pushes
3500 * running tasks off the busiest CPU onto idle CPUs. It requires at
3501 * least 1 task to be running on each physical CPU where possible, and
3502 * avoids physical / logical imbalances.
3504 static int active_load_balance_cpu_stop(void *data
)
3506 struct rq
*busiest_rq
= data
;
3507 int busiest_cpu
= cpu_of(busiest_rq
);
3508 int target_cpu
= busiest_rq
->push_cpu
;
3509 struct rq
*target_rq
= cpu_rq(target_cpu
);
3510 struct sched_domain
*sd
;
3512 raw_spin_lock_irq(&busiest_rq
->lock
);
3514 /* make sure the requested cpu hasn't gone down in the meantime */
3515 if (unlikely(busiest_cpu
!= smp_processor_id() ||
3516 !busiest_rq
->active_balance
))
3519 /* Is there any task to move? */
3520 if (busiest_rq
->nr_running
<= 1)
3524 * This condition is "impossible", if it occurs
3525 * we need to fix it. Originally reported by
3526 * Bjorn Helgaas on a 128-cpu setup.
3528 BUG_ON(busiest_rq
== target_rq
);
3530 /* move a task from busiest_rq to target_rq */
3531 double_lock_balance(busiest_rq
, target_rq
);
3533 /* Search for an sd spanning us and the target CPU. */
3534 for_each_domain(target_cpu
, sd
) {
3535 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
3536 cpumask_test_cpu(busiest_cpu
, sched_domain_span(sd
)))
3541 schedstat_inc(sd
, alb_count
);
3543 if (move_one_task(target_rq
, target_cpu
, busiest_rq
,
3545 schedstat_inc(sd
, alb_pushed
);
3547 schedstat_inc(sd
, alb_failed
);
3549 double_unlock_balance(busiest_rq
, target_rq
);
3551 busiest_rq
->active_balance
= 0;
3552 raw_spin_unlock_irq(&busiest_rq
->lock
);
3558 static DEFINE_PER_CPU(struct call_single_data
, remote_sched_softirq_cb
);
3560 static void trigger_sched_softirq(void *data
)
3562 raise_softirq_irqoff(SCHED_SOFTIRQ
);
3565 static inline void init_sched_softirq_csd(struct call_single_data
*csd
)
3567 csd
->func
= trigger_sched_softirq
;
3574 * idle load balancing details
3575 * - One of the idle CPUs nominates itself as idle load_balancer, while
3577 * - This idle load balancer CPU will also go into tickless mode when
3578 * it is idle, just like all other idle CPUs
3579 * - When one of the busy CPUs notice that there may be an idle rebalancing
3580 * needed, they will kick the idle load balancer, which then does idle
3581 * load balancing for all the idle CPUs.
3584 atomic_t load_balancer
;
3585 atomic_t first_pick_cpu
;
3586 atomic_t second_pick_cpu
;
3587 cpumask_var_t idle_cpus_mask
;
3588 cpumask_var_t grp_idle_mask
;
3589 unsigned long next_balance
; /* in jiffy units */
3590 } nohz ____cacheline_aligned
;
3592 int get_nohz_load_balancer(void)
3594 return atomic_read(&nohz
.load_balancer
);
3597 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
3599 * lowest_flag_domain - Return lowest sched_domain containing flag.
3600 * @cpu: The cpu whose lowest level of sched domain is to
3602 * @flag: The flag to check for the lowest sched_domain
3603 * for the given cpu.
3605 * Returns the lowest sched_domain of a cpu which contains the given flag.
3607 static inline struct sched_domain
*lowest_flag_domain(int cpu
, int flag
)
3609 struct sched_domain
*sd
;
3611 for_each_domain(cpu
, sd
)
3612 if (sd
&& (sd
->flags
& flag
))
3619 * for_each_flag_domain - Iterates over sched_domains containing the flag.
3620 * @cpu: The cpu whose domains we're iterating over.
3621 * @sd: variable holding the value of the power_savings_sd
3623 * @flag: The flag to filter the sched_domains to be iterated.
3625 * Iterates over all the scheduler domains for a given cpu that has the 'flag'
3626 * set, starting from the lowest sched_domain to the highest.
3628 #define for_each_flag_domain(cpu, sd, flag) \
3629 for (sd = lowest_flag_domain(cpu, flag); \
3630 (sd && (sd->flags & flag)); sd = sd->parent)
3633 * is_semi_idle_group - Checks if the given sched_group is semi-idle.
3634 * @ilb_group: group to be checked for semi-idleness
3636 * Returns: 1 if the group is semi-idle. 0 otherwise.
3638 * We define a sched_group to be semi idle if it has atleast one idle-CPU
3639 * and atleast one non-idle CPU. This helper function checks if the given
3640 * sched_group is semi-idle or not.
3642 static inline int is_semi_idle_group(struct sched_group
*ilb_group
)
3644 cpumask_and(nohz
.grp_idle_mask
, nohz
.idle_cpus_mask
,
3645 sched_group_cpus(ilb_group
));
3648 * A sched_group is semi-idle when it has atleast one busy cpu
3649 * and atleast one idle cpu.
3651 if (cpumask_empty(nohz
.grp_idle_mask
))
3654 if (cpumask_equal(nohz
.grp_idle_mask
, sched_group_cpus(ilb_group
)))
3660 * find_new_ilb - Finds the optimum idle load balancer for nomination.
3661 * @cpu: The cpu which is nominating a new idle_load_balancer.
3663 * Returns: Returns the id of the idle load balancer if it exists,
3664 * Else, returns >= nr_cpu_ids.
3666 * This algorithm picks the idle load balancer such that it belongs to a
3667 * semi-idle powersavings sched_domain. The idea is to try and avoid
3668 * completely idle packages/cores just for the purpose of idle load balancing
3669 * when there are other idle cpu's which are better suited for that job.
3671 static int find_new_ilb(int cpu
)
3673 struct sched_domain
*sd
;
3674 struct sched_group
*ilb_group
;
3677 * Have idle load balancer selection from semi-idle packages only
3678 * when power-aware load balancing is enabled
3680 if (!(sched_smt_power_savings
|| sched_mc_power_savings
))
3684 * Optimize for the case when we have no idle CPUs or only one
3685 * idle CPU. Don't walk the sched_domain hierarchy in such cases
3687 if (cpumask_weight(nohz
.idle_cpus_mask
) < 2)
3690 for_each_flag_domain(cpu
, sd
, SD_POWERSAVINGS_BALANCE
) {
3691 ilb_group
= sd
->groups
;
3694 if (is_semi_idle_group(ilb_group
))
3695 return cpumask_first(nohz
.grp_idle_mask
);
3697 ilb_group
= ilb_group
->next
;
3699 } while (ilb_group
!= sd
->groups
);
3705 #else /* (CONFIG_SCHED_MC || CONFIG_SCHED_SMT) */
3706 static inline int find_new_ilb(int call_cpu
)
3713 * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
3714 * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
3715 * CPU (if there is one).
3717 static void nohz_balancer_kick(int cpu
)
3721 nohz
.next_balance
++;
3723 ilb_cpu
= get_nohz_load_balancer();
3725 if (ilb_cpu
>= nr_cpu_ids
) {
3726 ilb_cpu
= cpumask_first(nohz
.idle_cpus_mask
);
3727 if (ilb_cpu
>= nr_cpu_ids
)
3731 if (!cpu_rq(ilb_cpu
)->nohz_balance_kick
) {
3732 struct call_single_data
*cp
;
3734 cpu_rq(ilb_cpu
)->nohz_balance_kick
= 1;
3735 cp
= &per_cpu(remote_sched_softirq_cb
, cpu
);
3736 __smp_call_function_single(ilb_cpu
, cp
, 0);
3742 * This routine will try to nominate the ilb (idle load balancing)
3743 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
3744 * load balancing on behalf of all those cpus.
3746 * When the ilb owner becomes busy, we will not have new ilb owner until some
3747 * idle CPU wakes up and goes back to idle or some busy CPU tries to kick
3748 * idle load balancing by kicking one of the idle CPUs.
3750 * Ticks are stopped for the ilb owner as well, with busy CPU kicking this
3751 * ilb owner CPU in future (when there is a need for idle load balancing on
3752 * behalf of all idle CPUs).
3754 void select_nohz_load_balancer(int stop_tick
)
3756 int cpu
= smp_processor_id();
3759 if (!cpu_active(cpu
)) {
3760 if (atomic_read(&nohz
.load_balancer
) != cpu
)
3764 * If we are going offline and still the leader,
3767 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
,
3774 cpumask_set_cpu(cpu
, nohz
.idle_cpus_mask
);
3776 if (atomic_read(&nohz
.first_pick_cpu
) == cpu
)
3777 atomic_cmpxchg(&nohz
.first_pick_cpu
, cpu
, nr_cpu_ids
);
3778 if (atomic_read(&nohz
.second_pick_cpu
) == cpu
)
3779 atomic_cmpxchg(&nohz
.second_pick_cpu
, cpu
, nr_cpu_ids
);
3781 if (atomic_read(&nohz
.load_balancer
) >= nr_cpu_ids
) {
3784 /* make me the ilb owner */
3785 if (atomic_cmpxchg(&nohz
.load_balancer
, nr_cpu_ids
,
3790 * Check to see if there is a more power-efficient
3793 new_ilb
= find_new_ilb(cpu
);
3794 if (new_ilb
< nr_cpu_ids
&& new_ilb
!= cpu
) {
3795 atomic_set(&nohz
.load_balancer
, nr_cpu_ids
);
3796 resched_cpu(new_ilb
);
3802 if (!cpumask_test_cpu(cpu
, nohz
.idle_cpus_mask
))
3805 cpumask_clear_cpu(cpu
, nohz
.idle_cpus_mask
);
3807 if (atomic_read(&nohz
.load_balancer
) == cpu
)
3808 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
,
3816 static DEFINE_SPINLOCK(balancing
);
3818 static unsigned long __read_mostly max_load_balance_interval
= HZ
/10;
3821 * Scale the max load_balance interval with the number of CPUs in the system.
3822 * This trades load-balance latency on larger machines for less cross talk.
3824 static void update_max_interval(void)
3826 max_load_balance_interval
= HZ
*num_online_cpus()/10;
3830 * It checks each scheduling domain to see if it is due to be balanced,
3831 * and initiates a balancing operation if so.
3833 * Balancing parameters are set up in arch_init_sched_domains.
3835 static void rebalance_domains(int cpu
, enum cpu_idle_type idle
)
3838 struct rq
*rq
= cpu_rq(cpu
);
3839 unsigned long interval
;
3840 struct sched_domain
*sd
;
3841 /* Earliest time when we have to do rebalance again */
3842 unsigned long next_balance
= jiffies
+ 60*HZ
;
3843 int update_next_balance
= 0;
3848 for_each_domain(cpu
, sd
) {
3849 if (!(sd
->flags
& SD_LOAD_BALANCE
))
3852 interval
= sd
->balance_interval
;
3853 if (idle
!= CPU_IDLE
)
3854 interval
*= sd
->busy_factor
;
3856 /* scale ms to jiffies */
3857 interval
= msecs_to_jiffies(interval
);
3858 interval
= clamp(interval
, 1UL, max_load_balance_interval
);
3860 need_serialize
= sd
->flags
& SD_SERIALIZE
;
3862 if (need_serialize
) {
3863 if (!spin_trylock(&balancing
))
3867 if (time_after_eq(jiffies
, sd
->last_balance
+ interval
)) {
3868 if (load_balance(cpu
, rq
, sd
, idle
, &balance
)) {
3870 * We've pulled tasks over so either we're no
3873 idle
= CPU_NOT_IDLE
;
3875 sd
->last_balance
= jiffies
;
3878 spin_unlock(&balancing
);
3880 if (time_after(next_balance
, sd
->last_balance
+ interval
)) {
3881 next_balance
= sd
->last_balance
+ interval
;
3882 update_next_balance
= 1;
3886 * Stop the load balance at this level. There is another
3887 * CPU in our sched group which is doing load balancing more
3895 * next_balance will be updated only when there is a need.
3896 * When the cpu is attached to null domain for ex, it will not be
3899 if (likely(update_next_balance
))
3900 rq
->next_balance
= next_balance
;
3905 * In CONFIG_NO_HZ case, the idle balance kickee will do the
3906 * rebalancing for all the cpus for whom scheduler ticks are stopped.
3908 static void nohz_idle_balance(int this_cpu
, enum cpu_idle_type idle
)
3910 struct rq
*this_rq
= cpu_rq(this_cpu
);
3914 if (idle
!= CPU_IDLE
|| !this_rq
->nohz_balance_kick
)
3917 for_each_cpu(balance_cpu
, nohz
.idle_cpus_mask
) {
3918 if (balance_cpu
== this_cpu
)
3922 * If this cpu gets work to do, stop the load balancing
3923 * work being done for other cpus. Next load
3924 * balancing owner will pick it up.
3926 if (need_resched()) {
3927 this_rq
->nohz_balance_kick
= 0;
3931 raw_spin_lock_irq(&this_rq
->lock
);
3932 update_rq_clock(this_rq
);
3933 update_cpu_load(this_rq
);
3934 raw_spin_unlock_irq(&this_rq
->lock
);
3936 rebalance_domains(balance_cpu
, CPU_IDLE
);
3938 rq
= cpu_rq(balance_cpu
);
3939 if (time_after(this_rq
->next_balance
, rq
->next_balance
))
3940 this_rq
->next_balance
= rq
->next_balance
;
3942 nohz
.next_balance
= this_rq
->next_balance
;
3943 this_rq
->nohz_balance_kick
= 0;
3947 * Current heuristic for kicking the idle load balancer
3948 * - first_pick_cpu is the one of the busy CPUs. It will kick
3949 * idle load balancer when it has more than one process active. This
3950 * eliminates the need for idle load balancing altogether when we have
3951 * only one running process in the system (common case).
3952 * - If there are more than one busy CPU, idle load balancer may have
3953 * to run for active_load_balance to happen (i.e., two busy CPUs are
3954 * SMT or core siblings and can run better if they move to different
3955 * physical CPUs). So, second_pick_cpu is the second of the busy CPUs
3956 * which will kick idle load balancer as soon as it has any load.
3958 static inline int nohz_kick_needed(struct rq
*rq
, int cpu
)
3960 unsigned long now
= jiffies
;
3962 int first_pick_cpu
, second_pick_cpu
;
3964 if (time_before(now
, nohz
.next_balance
))
3967 if (rq
->idle_at_tick
)
3970 first_pick_cpu
= atomic_read(&nohz
.first_pick_cpu
);
3971 second_pick_cpu
= atomic_read(&nohz
.second_pick_cpu
);
3973 if (first_pick_cpu
< nr_cpu_ids
&& first_pick_cpu
!= cpu
&&
3974 second_pick_cpu
< nr_cpu_ids
&& second_pick_cpu
!= cpu
)
3977 ret
= atomic_cmpxchg(&nohz
.first_pick_cpu
, nr_cpu_ids
, cpu
);
3978 if (ret
== nr_cpu_ids
|| ret
== cpu
) {
3979 atomic_cmpxchg(&nohz
.second_pick_cpu
, cpu
, nr_cpu_ids
);
3980 if (rq
->nr_running
> 1)
3983 ret
= atomic_cmpxchg(&nohz
.second_pick_cpu
, nr_cpu_ids
, cpu
);
3984 if (ret
== nr_cpu_ids
|| ret
== cpu
) {
3992 static void nohz_idle_balance(int this_cpu
, enum cpu_idle_type idle
) { }
3996 * run_rebalance_domains is triggered when needed from the scheduler tick.
3997 * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
3999 static void run_rebalance_domains(struct softirq_action
*h
)
4001 int this_cpu
= smp_processor_id();
4002 struct rq
*this_rq
= cpu_rq(this_cpu
);
4003 enum cpu_idle_type idle
= this_rq
->idle_at_tick
?
4004 CPU_IDLE
: CPU_NOT_IDLE
;
4006 rebalance_domains(this_cpu
, idle
);
4009 * If this cpu has a pending nohz_balance_kick, then do the
4010 * balancing on behalf of the other idle cpus whose ticks are
4013 nohz_idle_balance(this_cpu
, idle
);
4016 static inline int on_null_domain(int cpu
)
4018 return !rcu_dereference_sched(cpu_rq(cpu
)->sd
);
4022 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
4024 static inline void trigger_load_balance(struct rq
*rq
, int cpu
)
4026 /* Don't need to rebalance while attached to NULL domain */
4027 if (time_after_eq(jiffies
, rq
->next_balance
) &&
4028 likely(!on_null_domain(cpu
)))
4029 raise_softirq(SCHED_SOFTIRQ
);
4031 else if (nohz_kick_needed(rq
, cpu
) && likely(!on_null_domain(cpu
)))
4032 nohz_balancer_kick(cpu
);
4036 static void rq_online_fair(struct rq
*rq
)
4041 static void rq_offline_fair(struct rq
*rq
)
4046 #else /* CONFIG_SMP */
4049 * on UP we do not need to balance between CPUs:
4051 static inline void idle_balance(int cpu
, struct rq
*rq
)
4055 #endif /* CONFIG_SMP */
4058 * scheduler tick hitting a task of our scheduling class:
4060 static void task_tick_fair(struct rq
*rq
, struct task_struct
*curr
, int queued
)
4062 struct cfs_rq
*cfs_rq
;
4063 struct sched_entity
*se
= &curr
->se
;
4065 for_each_sched_entity(se
) {
4066 cfs_rq
= cfs_rq_of(se
);
4067 entity_tick(cfs_rq
, se
, queued
);
4072 * called on fork with the child task as argument from the parent's context
4073 * - child not yet on the tasklist
4074 * - preemption disabled
4076 static void task_fork_fair(struct task_struct
*p
)
4078 struct cfs_rq
*cfs_rq
= task_cfs_rq(current
);
4079 struct sched_entity
*se
= &p
->se
, *curr
= cfs_rq
->curr
;
4080 int this_cpu
= smp_processor_id();
4081 struct rq
*rq
= this_rq();
4082 unsigned long flags
;
4084 raw_spin_lock_irqsave(&rq
->lock
, flags
);
4086 update_rq_clock(rq
);
4088 if (unlikely(task_cpu(p
) != this_cpu
)) {
4090 __set_task_cpu(p
, this_cpu
);
4094 update_curr(cfs_rq
);
4097 se
->vruntime
= curr
->vruntime
;
4098 place_entity(cfs_rq
, se
, 1);
4100 if (sysctl_sched_child_runs_first
&& curr
&& entity_before(curr
, se
)) {
4102 * Upon rescheduling, sched_class::put_prev_task() will place
4103 * 'current' within the tree based on its new key value.
4105 swap(curr
->vruntime
, se
->vruntime
);
4106 resched_task(rq
->curr
);
4109 se
->vruntime
-= cfs_rq
->min_vruntime
;
4111 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
4115 * Priority of the task has changed. Check to see if we preempt
4119 prio_changed_fair(struct rq
*rq
, struct task_struct
*p
, int oldprio
)
4125 * Reschedule if we are currently running on this runqueue and
4126 * our priority decreased, or if we are not currently running on
4127 * this runqueue and our priority is higher than the current's
4129 if (rq
->curr
== p
) {
4130 if (p
->prio
> oldprio
)
4131 resched_task(rq
->curr
);
4133 check_preempt_curr(rq
, p
, 0);
4136 static void switched_from_fair(struct rq
*rq
, struct task_struct
*p
)
4138 struct sched_entity
*se
= &p
->se
;
4139 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
4142 * Ensure the task's vruntime is normalized, so that when its
4143 * switched back to the fair class the enqueue_entity(.flags=0) will
4144 * do the right thing.
4146 * If it was on_rq, then the dequeue_entity(.flags=0) will already
4147 * have normalized the vruntime, if it was !on_rq, then only when
4148 * the task is sleeping will it still have non-normalized vruntime.
4150 if (!se
->on_rq
&& p
->state
!= TASK_RUNNING
) {
4152 * Fix up our vruntime so that the current sleep doesn't
4153 * cause 'unlimited' sleep bonus.
4155 place_entity(cfs_rq
, se
, 0);
4156 se
->vruntime
-= cfs_rq
->min_vruntime
;
4161 * We switched to the sched_fair class.
4163 static void switched_to_fair(struct rq
*rq
, struct task_struct
*p
)
4169 * We were most likely switched from sched_rt, so
4170 * kick off the schedule if running, otherwise just see
4171 * if we can still preempt the current task.
4174 resched_task(rq
->curr
);
4176 check_preempt_curr(rq
, p
, 0);
4179 /* Account for a task changing its policy or group.
4181 * This routine is mostly called to set cfs_rq->curr field when a task
4182 * migrates between groups/classes.
4184 static void set_curr_task_fair(struct rq
*rq
)
4186 struct sched_entity
*se
= &rq
->curr
->se
;
4188 for_each_sched_entity(se
)
4189 set_next_entity(cfs_rq_of(se
), se
);
4192 #ifdef CONFIG_FAIR_GROUP_SCHED
4193 static void task_move_group_fair(struct task_struct
*p
, int on_rq
)
4196 * If the task was not on the rq at the time of this cgroup movement
4197 * it must have been asleep, sleeping tasks keep their ->vruntime
4198 * absolute on their old rq until wakeup (needed for the fair sleeper
4199 * bonus in place_entity()).
4201 * If it was on the rq, we've just 'preempted' it, which does convert
4202 * ->vruntime to a relative base.
4204 * Make sure both cases convert their relative position when migrating
4205 * to another cgroup's rq. This does somewhat interfere with the
4206 * fair sleeper stuff for the first placement, but who cares.
4209 p
->se
.vruntime
-= cfs_rq_of(&p
->se
)->min_vruntime
;
4210 set_task_rq(p
, task_cpu(p
));
4212 p
->se
.vruntime
+= cfs_rq_of(&p
->se
)->min_vruntime
;
4216 static unsigned int get_rr_interval_fair(struct rq
*rq
, struct task_struct
*task
)
4218 struct sched_entity
*se
= &task
->se
;
4219 unsigned int rr_interval
= 0;
4222 * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
4225 if (rq
->cfs
.load
.weight
)
4226 rr_interval
= NS_TO_JIFFIES(sched_slice(&rq
->cfs
, se
));
4232 * All the scheduling class methods:
4234 static const struct sched_class fair_sched_class
= {
4235 .next
= &idle_sched_class
,
4236 .enqueue_task
= enqueue_task_fair
,
4237 .dequeue_task
= dequeue_task_fair
,
4238 .yield_task
= yield_task_fair
,
4239 .yield_to_task
= yield_to_task_fair
,
4241 .check_preempt_curr
= check_preempt_wakeup
,
4243 .pick_next_task
= pick_next_task_fair
,
4244 .put_prev_task
= put_prev_task_fair
,
4247 .select_task_rq
= select_task_rq_fair
,
4249 .rq_online
= rq_online_fair
,
4250 .rq_offline
= rq_offline_fair
,
4252 .task_waking
= task_waking_fair
,
4255 .set_curr_task
= set_curr_task_fair
,
4256 .task_tick
= task_tick_fair
,
4257 .task_fork
= task_fork_fair
,
4259 .prio_changed
= prio_changed_fair
,
4260 .switched_from
= switched_from_fair
,
4261 .switched_to
= switched_to_fair
,
4263 .get_rr_interval
= get_rr_interval_fair
,
4265 #ifdef CONFIG_FAIR_GROUP_SCHED
4266 .task_move_group
= task_move_group_fair
,
4270 #ifdef CONFIG_SCHED_DEBUG
4271 static void print_cfs_stats(struct seq_file
*m
, int cpu
)
4273 struct cfs_rq
*cfs_rq
;
4276 for_each_leaf_cfs_rq(cpu_rq(cpu
), cfs_rq
)
4277 print_cfs_rq(m
, cpu
, cfs_rq
);