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
23 #include <linux/sched.h>
24 #include <linux/latencytop.h>
25 #include <linux/cpumask.h>
26 #include <linux/cpuidle.h>
27 #include <linux/slab.h>
28 #include <linux/profile.h>
29 #include <linux/interrupt.h>
30 #include <linux/mempolicy.h>
31 #include <linux/migrate.h>
32 #include <linux/task_work.h>
34 #include <trace/events/sched.h>
39 * Targeted preemption latency for CPU-bound tasks:
40 * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
42 * NOTE: this latency value is not the same as the concept of
43 * 'timeslice length' - timeslices in CFS are of variable length
44 * and have no persistent notion like in traditional, time-slice
45 * based scheduling concepts.
47 * (to see the precise effective timeslice length of your workload,
48 * run vmstat and monitor the context-switches (cs) field)
50 unsigned int sysctl_sched_latency
= 6000000ULL;
51 unsigned int normalized_sysctl_sched_latency
= 6000000ULL;
54 * The initial- and re-scaling of tunables is configurable
55 * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
58 * SCHED_TUNABLESCALING_NONE - unscaled, always *1
59 * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
60 * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
62 enum sched_tunable_scaling sysctl_sched_tunable_scaling
63 = SCHED_TUNABLESCALING_LOG
;
66 * Minimal preemption granularity for CPU-bound tasks:
67 * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
69 unsigned int sysctl_sched_min_granularity
= 750000ULL;
70 unsigned int normalized_sysctl_sched_min_granularity
= 750000ULL;
73 * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
75 static unsigned int sched_nr_latency
= 8;
78 * After fork, child runs first. If set to 0 (default) then
79 * parent will (try to) run first.
81 unsigned int sysctl_sched_child_runs_first __read_mostly
;
84 * SCHED_OTHER wake-up granularity.
85 * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
87 * This option delays the preemption effects of decoupled workloads
88 * and reduces their over-scheduling. Synchronous workloads will still
89 * have immediate wakeup/sleep latencies.
91 unsigned int sysctl_sched_wakeup_granularity
= 1000000UL;
92 unsigned int normalized_sysctl_sched_wakeup_granularity
= 1000000UL;
94 const_debug
unsigned int sysctl_sched_migration_cost
= 500000UL;
97 * The exponential sliding window over which load is averaged for shares
101 unsigned int __read_mostly sysctl_sched_shares_window
= 10000000UL;
103 #ifdef CONFIG_CFS_BANDWIDTH
105 * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
106 * each time a cfs_rq requests quota.
108 * Note: in the case that the slice exceeds the runtime remaining (either due
109 * to consumption or the quota being specified to be smaller than the slice)
110 * we will always only issue the remaining available time.
112 * default: 5 msec, units: microseconds
114 unsigned int sysctl_sched_cfs_bandwidth_slice
= 5000UL;
117 static inline void update_load_add(struct load_weight
*lw
, unsigned long inc
)
123 static inline void update_load_sub(struct load_weight
*lw
, unsigned long dec
)
129 static inline void update_load_set(struct load_weight
*lw
, unsigned long w
)
136 * Increase the granularity value when there are more CPUs,
137 * because with more CPUs the 'effective latency' as visible
138 * to users decreases. But the relationship is not linear,
139 * so pick a second-best guess by going with the log2 of the
142 * This idea comes from the SD scheduler of Con Kolivas:
144 static unsigned int get_update_sysctl_factor(void)
146 unsigned int cpus
= min_t(unsigned int, num_online_cpus(), 8);
149 switch (sysctl_sched_tunable_scaling
) {
150 case SCHED_TUNABLESCALING_NONE
:
153 case SCHED_TUNABLESCALING_LINEAR
:
156 case SCHED_TUNABLESCALING_LOG
:
158 factor
= 1 + ilog2(cpus
);
165 static void update_sysctl(void)
167 unsigned int factor
= get_update_sysctl_factor();
169 #define SET_SYSCTL(name) \
170 (sysctl_##name = (factor) * normalized_sysctl_##name)
171 SET_SYSCTL(sched_min_granularity
);
172 SET_SYSCTL(sched_latency
);
173 SET_SYSCTL(sched_wakeup_granularity
);
177 void sched_init_granularity(void)
182 #define WMULT_CONST (~0U)
183 #define WMULT_SHIFT 32
185 static void __update_inv_weight(struct load_weight
*lw
)
189 if (likely(lw
->inv_weight
))
192 w
= scale_load_down(lw
->weight
);
194 if (BITS_PER_LONG
> 32 && unlikely(w
>= WMULT_CONST
))
196 else if (unlikely(!w
))
197 lw
->inv_weight
= WMULT_CONST
;
199 lw
->inv_weight
= WMULT_CONST
/ w
;
203 * delta_exec * weight / lw.weight
205 * (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT
207 * Either weight := NICE_0_LOAD and lw \e sched_prio_to_wmult[], in which case
208 * we're guaranteed shift stays positive because inv_weight is guaranteed to
209 * fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22.
211 * Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus
212 * weight/lw.weight <= 1, and therefore our shift will also be positive.
214 static u64
__calc_delta(u64 delta_exec
, unsigned long weight
, struct load_weight
*lw
)
216 u64 fact
= scale_load_down(weight
);
217 int shift
= WMULT_SHIFT
;
219 __update_inv_weight(lw
);
221 if (unlikely(fact
>> 32)) {
228 /* hint to use a 32x32->64 mul */
229 fact
= (u64
)(u32
)fact
* lw
->inv_weight
;
236 return mul_u64_u32_shr(delta_exec
, fact
, shift
);
240 const struct sched_class fair_sched_class
;
242 /**************************************************************
243 * CFS operations on generic schedulable entities:
246 #ifdef CONFIG_FAIR_GROUP_SCHED
248 /* cpu runqueue to which this cfs_rq is attached */
249 static inline struct rq
*rq_of(struct cfs_rq
*cfs_rq
)
254 /* An entity is a task if it doesn't "own" a runqueue */
255 #define entity_is_task(se) (!se->my_q)
257 static inline struct task_struct
*task_of(struct sched_entity
*se
)
259 #ifdef CONFIG_SCHED_DEBUG
260 WARN_ON_ONCE(!entity_is_task(se
));
262 return container_of(se
, struct task_struct
, se
);
265 /* Walk up scheduling entities hierarchy */
266 #define for_each_sched_entity(se) \
267 for (; se; se = se->parent)
269 static inline struct cfs_rq
*task_cfs_rq(struct task_struct
*p
)
274 /* runqueue on which this entity is (to be) queued */
275 static inline struct cfs_rq
*cfs_rq_of(struct sched_entity
*se
)
280 /* runqueue "owned" by this group */
281 static inline struct cfs_rq
*group_cfs_rq(struct sched_entity
*grp
)
286 static inline void list_add_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
288 if (!cfs_rq
->on_list
) {
290 * Ensure we either appear before our parent (if already
291 * enqueued) or force our parent to appear after us when it is
292 * enqueued. The fact that we always enqueue bottom-up
293 * reduces this to two cases.
295 if (cfs_rq
->tg
->parent
&&
296 cfs_rq
->tg
->parent
->cfs_rq
[cpu_of(rq_of(cfs_rq
))]->on_list
) {
297 list_add_rcu(&cfs_rq
->leaf_cfs_rq_list
,
298 &rq_of(cfs_rq
)->leaf_cfs_rq_list
);
300 list_add_tail_rcu(&cfs_rq
->leaf_cfs_rq_list
,
301 &rq_of(cfs_rq
)->leaf_cfs_rq_list
);
308 static inline void list_del_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
310 if (cfs_rq
->on_list
) {
311 list_del_rcu(&cfs_rq
->leaf_cfs_rq_list
);
316 /* Iterate thr' all leaf cfs_rq's on a runqueue */
317 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
318 list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
320 /* Do the two (enqueued) entities belong to the same group ? */
321 static inline struct cfs_rq
*
322 is_same_group(struct sched_entity
*se
, struct sched_entity
*pse
)
324 if (se
->cfs_rq
== pse
->cfs_rq
)
330 static inline struct sched_entity
*parent_entity(struct sched_entity
*se
)
336 find_matching_se(struct sched_entity
**se
, struct sched_entity
**pse
)
338 int se_depth
, pse_depth
;
341 * preemption test can be made between sibling entities who are in the
342 * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
343 * both tasks until we find their ancestors who are siblings of common
347 /* First walk up until both entities are at same depth */
348 se_depth
= (*se
)->depth
;
349 pse_depth
= (*pse
)->depth
;
351 while (se_depth
> pse_depth
) {
353 *se
= parent_entity(*se
);
356 while (pse_depth
> se_depth
) {
358 *pse
= parent_entity(*pse
);
361 while (!is_same_group(*se
, *pse
)) {
362 *se
= parent_entity(*se
);
363 *pse
= parent_entity(*pse
);
367 #else /* !CONFIG_FAIR_GROUP_SCHED */
369 static inline struct task_struct
*task_of(struct sched_entity
*se
)
371 return container_of(se
, struct task_struct
, se
);
374 static inline struct rq
*rq_of(struct cfs_rq
*cfs_rq
)
376 return container_of(cfs_rq
, struct rq
, cfs
);
379 #define entity_is_task(se) 1
381 #define for_each_sched_entity(se) \
382 for (; se; se = NULL)
384 static inline struct cfs_rq
*task_cfs_rq(struct task_struct
*p
)
386 return &task_rq(p
)->cfs
;
389 static inline struct cfs_rq
*cfs_rq_of(struct sched_entity
*se
)
391 struct task_struct
*p
= task_of(se
);
392 struct rq
*rq
= task_rq(p
);
397 /* runqueue "owned" by this group */
398 static inline struct cfs_rq
*group_cfs_rq(struct sched_entity
*grp
)
403 static inline void list_add_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
407 static inline void list_del_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
411 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
412 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
414 static inline struct sched_entity
*parent_entity(struct sched_entity
*se
)
420 find_matching_se(struct sched_entity
**se
, struct sched_entity
**pse
)
424 #endif /* CONFIG_FAIR_GROUP_SCHED */
426 static __always_inline
427 void account_cfs_rq_runtime(struct cfs_rq
*cfs_rq
, u64 delta_exec
);
429 /**************************************************************
430 * Scheduling class tree data structure manipulation methods:
433 static inline u64
max_vruntime(u64 max_vruntime
, u64 vruntime
)
435 s64 delta
= (s64
)(vruntime
- max_vruntime
);
437 max_vruntime
= vruntime
;
442 static inline u64
min_vruntime(u64 min_vruntime
, u64 vruntime
)
444 s64 delta
= (s64
)(vruntime
- min_vruntime
);
446 min_vruntime
= vruntime
;
451 static inline int entity_before(struct sched_entity
*a
,
452 struct sched_entity
*b
)
454 return (s64
)(a
->vruntime
- b
->vruntime
) < 0;
457 static void update_min_vruntime(struct cfs_rq
*cfs_rq
)
459 u64 vruntime
= cfs_rq
->min_vruntime
;
462 vruntime
= cfs_rq
->curr
->vruntime
;
464 if (cfs_rq
->rb_leftmost
) {
465 struct sched_entity
*se
= rb_entry(cfs_rq
->rb_leftmost
,
470 vruntime
= se
->vruntime
;
472 vruntime
= min_vruntime(vruntime
, se
->vruntime
);
475 /* ensure we never gain time by being placed backwards. */
476 cfs_rq
->min_vruntime
= max_vruntime(cfs_rq
->min_vruntime
, vruntime
);
479 cfs_rq
->min_vruntime_copy
= cfs_rq
->min_vruntime
;
484 * Enqueue an entity into the rb-tree:
486 static void __enqueue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
488 struct rb_node
**link
= &cfs_rq
->tasks_timeline
.rb_node
;
489 struct rb_node
*parent
= NULL
;
490 struct sched_entity
*entry
;
494 * Find the right place in the rbtree:
498 entry
= rb_entry(parent
, struct sched_entity
, run_node
);
500 * We dont care about collisions. Nodes with
501 * the same key stay together.
503 if (entity_before(se
, entry
)) {
504 link
= &parent
->rb_left
;
506 link
= &parent
->rb_right
;
512 * Maintain a cache of leftmost tree entries (it is frequently
516 cfs_rq
->rb_leftmost
= &se
->run_node
;
518 rb_link_node(&se
->run_node
, parent
, link
);
519 rb_insert_color(&se
->run_node
, &cfs_rq
->tasks_timeline
);
522 static void __dequeue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
524 if (cfs_rq
->rb_leftmost
== &se
->run_node
) {
525 struct rb_node
*next_node
;
527 next_node
= rb_next(&se
->run_node
);
528 cfs_rq
->rb_leftmost
= next_node
;
531 rb_erase(&se
->run_node
, &cfs_rq
->tasks_timeline
);
534 struct sched_entity
*__pick_first_entity(struct cfs_rq
*cfs_rq
)
536 struct rb_node
*left
= cfs_rq
->rb_leftmost
;
541 return rb_entry(left
, struct sched_entity
, run_node
);
544 static struct sched_entity
*__pick_next_entity(struct sched_entity
*se
)
546 struct rb_node
*next
= rb_next(&se
->run_node
);
551 return rb_entry(next
, struct sched_entity
, run_node
);
554 #ifdef CONFIG_SCHED_DEBUG
555 struct sched_entity
*__pick_last_entity(struct cfs_rq
*cfs_rq
)
557 struct rb_node
*last
= rb_last(&cfs_rq
->tasks_timeline
);
562 return rb_entry(last
, struct sched_entity
, run_node
);
565 /**************************************************************
566 * Scheduling class statistics methods:
569 int sched_proc_update_handler(struct ctl_table
*table
, int write
,
570 void __user
*buffer
, size_t *lenp
,
573 int ret
= proc_dointvec_minmax(table
, write
, buffer
, lenp
, ppos
);
574 unsigned int factor
= get_update_sysctl_factor();
579 sched_nr_latency
= DIV_ROUND_UP(sysctl_sched_latency
,
580 sysctl_sched_min_granularity
);
582 #define WRT_SYSCTL(name) \
583 (normalized_sysctl_##name = sysctl_##name / (factor))
584 WRT_SYSCTL(sched_min_granularity
);
585 WRT_SYSCTL(sched_latency
);
586 WRT_SYSCTL(sched_wakeup_granularity
);
596 static inline u64
calc_delta_fair(u64 delta
, struct sched_entity
*se
)
598 if (unlikely(se
->load
.weight
!= NICE_0_LOAD
))
599 delta
= __calc_delta(delta
, NICE_0_LOAD
, &se
->load
);
605 * The idea is to set a period in which each task runs once.
607 * When there are too many tasks (sched_nr_latency) we have to stretch
608 * this period because otherwise the slices get too small.
610 * p = (nr <= nl) ? l : l*nr/nl
612 static u64
__sched_period(unsigned long nr_running
)
614 if (unlikely(nr_running
> sched_nr_latency
))
615 return nr_running
* sysctl_sched_min_granularity
;
617 return sysctl_sched_latency
;
621 * We calculate the wall-time slice from the period by taking a part
622 * proportional to the weight.
626 static u64
sched_slice(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
628 u64 slice
= __sched_period(cfs_rq
->nr_running
+ !se
->on_rq
);
630 for_each_sched_entity(se
) {
631 struct load_weight
*load
;
632 struct load_weight lw
;
634 cfs_rq
= cfs_rq_of(se
);
635 load
= &cfs_rq
->load
;
637 if (unlikely(!se
->on_rq
)) {
640 update_load_add(&lw
, se
->load
.weight
);
643 slice
= __calc_delta(slice
, se
->load
.weight
, load
);
649 * We calculate the vruntime slice of a to-be-inserted task.
653 static u64
sched_vslice(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
655 return calc_delta_fair(sched_slice(cfs_rq
, se
), se
);
659 static int select_idle_sibling(struct task_struct
*p
, int cpu
);
660 static unsigned long task_h_load(struct task_struct
*p
);
663 * We choose a half-life close to 1 scheduling period.
664 * Note: The tables runnable_avg_yN_inv and runnable_avg_yN_sum are
665 * dependent on this value.
667 #define LOAD_AVG_PERIOD 32
668 #define LOAD_AVG_MAX 47742 /* maximum possible load avg */
669 #define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_AVG_MAX */
671 /* Give new sched_entity start runnable values to heavy its load in infant time */
672 void init_entity_runnable_average(struct sched_entity
*se
)
674 struct sched_avg
*sa
= &se
->avg
;
676 sa
->last_update_time
= 0;
678 * sched_avg's period_contrib should be strictly less then 1024, so
679 * we give it 1023 to make sure it is almost a period (1024us), and
680 * will definitely be update (after enqueue).
682 sa
->period_contrib
= 1023;
683 sa
->load_avg
= scale_load_down(se
->load
.weight
);
684 sa
->load_sum
= sa
->load_avg
* LOAD_AVG_MAX
;
686 * At this point, util_avg won't be used in select_task_rq_fair anyway
690 /* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */
694 * With new tasks being created, their initial util_avgs are extrapolated
695 * based on the cfs_rq's current util_avg:
697 * util_avg = cfs_rq->util_avg / (cfs_rq->load_avg + 1) * se.load.weight
699 * However, in many cases, the above util_avg does not give a desired
700 * value. Moreover, the sum of the util_avgs may be divergent, such
701 * as when the series is a harmonic series.
703 * To solve this problem, we also cap the util_avg of successive tasks to
704 * only 1/2 of the left utilization budget:
706 * util_avg_cap = (1024 - cfs_rq->avg.util_avg) / 2^n
708 * where n denotes the nth task.
710 * For example, a simplest series from the beginning would be like:
712 * task util_avg: 512, 256, 128, 64, 32, 16, 8, ...
713 * cfs_rq util_avg: 512, 768, 896, 960, 992, 1008, 1016, ...
715 * Finally, that extrapolated util_avg is clamped to the cap (util_avg_cap)
716 * if util_avg > util_avg_cap.
718 void post_init_entity_util_avg(struct sched_entity
*se
)
720 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
721 struct sched_avg
*sa
= &se
->avg
;
722 long cap
= (long)(scale_load_down(SCHED_LOAD_SCALE
) - cfs_rq
->avg
.util_avg
) / 2;
725 if (cfs_rq
->avg
.util_avg
!= 0) {
726 sa
->util_avg
= cfs_rq
->avg
.util_avg
* se
->load
.weight
;
727 sa
->util_avg
/= (cfs_rq
->avg
.load_avg
+ 1);
729 if (sa
->util_avg
> cap
)
734 sa
->util_sum
= sa
->util_avg
* LOAD_AVG_MAX
;
738 static inline unsigned long cfs_rq_runnable_load_avg(struct cfs_rq
*cfs_rq
);
739 static inline unsigned long cfs_rq_load_avg(struct cfs_rq
*cfs_rq
);
741 void init_entity_runnable_average(struct sched_entity
*se
)
744 void post_init_entity_util_avg(struct sched_entity
*se
)
750 * Update the current task's runtime statistics.
752 static void update_curr(struct cfs_rq
*cfs_rq
)
754 struct sched_entity
*curr
= cfs_rq
->curr
;
755 u64 now
= rq_clock_task(rq_of(cfs_rq
));
761 delta_exec
= now
- curr
->exec_start
;
762 if (unlikely((s64
)delta_exec
<= 0))
765 curr
->exec_start
= now
;
767 schedstat_set(curr
->statistics
.exec_max
,
768 max(delta_exec
, curr
->statistics
.exec_max
));
770 curr
->sum_exec_runtime
+= delta_exec
;
771 schedstat_add(cfs_rq
, exec_clock
, delta_exec
);
773 curr
->vruntime
+= calc_delta_fair(delta_exec
, curr
);
774 update_min_vruntime(cfs_rq
);
776 if (entity_is_task(curr
)) {
777 struct task_struct
*curtask
= task_of(curr
);
779 trace_sched_stat_runtime(curtask
, delta_exec
, curr
->vruntime
);
780 cpuacct_charge(curtask
, delta_exec
);
781 account_group_exec_runtime(curtask
, delta_exec
);
784 account_cfs_rq_runtime(cfs_rq
, delta_exec
);
787 static void update_curr_fair(struct rq
*rq
)
789 update_curr(cfs_rq_of(&rq
->curr
->se
));
792 #ifdef CONFIG_SCHEDSTATS
794 update_stats_wait_start(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
796 u64 wait_start
= rq_clock(rq_of(cfs_rq
));
798 if (entity_is_task(se
) && task_on_rq_migrating(task_of(se
)) &&
799 likely(wait_start
> se
->statistics
.wait_start
))
800 wait_start
-= se
->statistics
.wait_start
;
802 se
->statistics
.wait_start
= wait_start
;
806 update_stats_wait_end(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
808 struct task_struct
*p
;
811 delta
= rq_clock(rq_of(cfs_rq
)) - se
->statistics
.wait_start
;
813 if (entity_is_task(se
)) {
815 if (task_on_rq_migrating(p
)) {
817 * Preserve migrating task's wait time so wait_start
818 * time stamp can be adjusted to accumulate wait time
819 * prior to migration.
821 se
->statistics
.wait_start
= delta
;
824 trace_sched_stat_wait(p
, delta
);
827 se
->statistics
.wait_max
= max(se
->statistics
.wait_max
, delta
);
828 se
->statistics
.wait_count
++;
829 se
->statistics
.wait_sum
+= delta
;
830 se
->statistics
.wait_start
= 0;
834 * Task is being enqueued - update stats:
837 update_stats_enqueue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
840 * Are we enqueueing a waiting task? (for current tasks
841 * a dequeue/enqueue event is a NOP)
843 if (se
!= cfs_rq
->curr
)
844 update_stats_wait_start(cfs_rq
, se
);
848 update_stats_dequeue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int flags
)
851 * Mark the end of the wait period if dequeueing a
854 if (se
!= cfs_rq
->curr
)
855 update_stats_wait_end(cfs_rq
, se
);
857 if (flags
& DEQUEUE_SLEEP
) {
858 if (entity_is_task(se
)) {
859 struct task_struct
*tsk
= task_of(se
);
861 if (tsk
->state
& TASK_INTERRUPTIBLE
)
862 se
->statistics
.sleep_start
= rq_clock(rq_of(cfs_rq
));
863 if (tsk
->state
& TASK_UNINTERRUPTIBLE
)
864 se
->statistics
.block_start
= rq_clock(rq_of(cfs_rq
));
871 update_stats_wait_start(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
876 update_stats_wait_end(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
881 update_stats_enqueue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
886 update_stats_dequeue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int flags
)
892 * We are picking a new current task - update its stats:
895 update_stats_curr_start(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
898 * We are starting a new run period:
900 se
->exec_start
= rq_clock_task(rq_of(cfs_rq
));
903 /**************************************************
904 * Scheduling class queueing methods:
907 #ifdef CONFIG_NUMA_BALANCING
909 * Approximate time to scan a full NUMA task in ms. The task scan period is
910 * calculated based on the tasks virtual memory size and
911 * numa_balancing_scan_size.
913 unsigned int sysctl_numa_balancing_scan_period_min
= 1000;
914 unsigned int sysctl_numa_balancing_scan_period_max
= 60000;
916 /* Portion of address space to scan in MB */
917 unsigned int sysctl_numa_balancing_scan_size
= 256;
919 /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */
920 unsigned int sysctl_numa_balancing_scan_delay
= 1000;
922 static unsigned int task_nr_scan_windows(struct task_struct
*p
)
924 unsigned long rss
= 0;
925 unsigned long nr_scan_pages
;
928 * Calculations based on RSS as non-present and empty pages are skipped
929 * by the PTE scanner and NUMA hinting faults should be trapped based
932 nr_scan_pages
= sysctl_numa_balancing_scan_size
<< (20 - PAGE_SHIFT
);
933 rss
= get_mm_rss(p
->mm
);
937 rss
= round_up(rss
, nr_scan_pages
);
938 return rss
/ nr_scan_pages
;
941 /* For sanitys sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */
942 #define MAX_SCAN_WINDOW 2560
944 static unsigned int task_scan_min(struct task_struct
*p
)
946 unsigned int scan_size
= READ_ONCE(sysctl_numa_balancing_scan_size
);
947 unsigned int scan
, floor
;
948 unsigned int windows
= 1;
950 if (scan_size
< MAX_SCAN_WINDOW
)
951 windows
= MAX_SCAN_WINDOW
/ scan_size
;
952 floor
= 1000 / windows
;
954 scan
= sysctl_numa_balancing_scan_period_min
/ task_nr_scan_windows(p
);
955 return max_t(unsigned int, floor
, scan
);
958 static unsigned int task_scan_max(struct task_struct
*p
)
960 unsigned int smin
= task_scan_min(p
);
963 /* Watch for min being lower than max due to floor calculations */
964 smax
= sysctl_numa_balancing_scan_period_max
/ task_nr_scan_windows(p
);
965 return max(smin
, smax
);
968 static void account_numa_enqueue(struct rq
*rq
, struct task_struct
*p
)
970 rq
->nr_numa_running
+= (p
->numa_preferred_nid
!= -1);
971 rq
->nr_preferred_running
+= (p
->numa_preferred_nid
== task_node(p
));
974 static void account_numa_dequeue(struct rq
*rq
, struct task_struct
*p
)
976 rq
->nr_numa_running
-= (p
->numa_preferred_nid
!= -1);
977 rq
->nr_preferred_running
-= (p
->numa_preferred_nid
== task_node(p
));
983 spinlock_t lock
; /* nr_tasks, tasks */
989 unsigned long total_faults
;
990 unsigned long max_faults_cpu
;
992 * Faults_cpu is used to decide whether memory should move
993 * towards the CPU. As a consequence, these stats are weighted
994 * more by CPU use than by memory faults.
996 unsigned long *faults_cpu
;
997 unsigned long faults
[0];
1000 /* Shared or private faults. */
1001 #define NR_NUMA_HINT_FAULT_TYPES 2
1003 /* Memory and CPU locality */
1004 #define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2)
1006 /* Averaged statistics, and temporary buffers. */
1007 #define NR_NUMA_HINT_FAULT_BUCKETS (NR_NUMA_HINT_FAULT_STATS * 2)
1009 pid_t
task_numa_group_id(struct task_struct
*p
)
1011 return p
->numa_group
? p
->numa_group
->gid
: 0;
1015 * The averaged statistics, shared & private, memory & cpu,
1016 * occupy the first half of the array. The second half of the
1017 * array is for current counters, which are averaged into the
1018 * first set by task_numa_placement.
1020 static inline int task_faults_idx(enum numa_faults_stats s
, int nid
, int priv
)
1022 return NR_NUMA_HINT_FAULT_TYPES
* (s
* nr_node_ids
+ nid
) + priv
;
1025 static inline unsigned long task_faults(struct task_struct
*p
, int nid
)
1027 if (!p
->numa_faults
)
1030 return p
->numa_faults
[task_faults_idx(NUMA_MEM
, nid
, 0)] +
1031 p
->numa_faults
[task_faults_idx(NUMA_MEM
, nid
, 1)];
1034 static inline unsigned long group_faults(struct task_struct
*p
, int nid
)
1039 return p
->numa_group
->faults
[task_faults_idx(NUMA_MEM
, nid
, 0)] +
1040 p
->numa_group
->faults
[task_faults_idx(NUMA_MEM
, nid
, 1)];
1043 static inline unsigned long group_faults_cpu(struct numa_group
*group
, int nid
)
1045 return group
->faults_cpu
[task_faults_idx(NUMA_MEM
, nid
, 0)] +
1046 group
->faults_cpu
[task_faults_idx(NUMA_MEM
, nid
, 1)];
1050 * A node triggering more than 1/3 as many NUMA faults as the maximum is
1051 * considered part of a numa group's pseudo-interleaving set. Migrations
1052 * between these nodes are slowed down, to allow things to settle down.
1054 #define ACTIVE_NODE_FRACTION 3
1056 static bool numa_is_active_node(int nid
, struct numa_group
*ng
)
1058 return group_faults_cpu(ng
, nid
) * ACTIVE_NODE_FRACTION
> ng
->max_faults_cpu
;
1061 /* Handle placement on systems where not all nodes are directly connected. */
1062 static unsigned long score_nearby_nodes(struct task_struct
*p
, int nid
,
1063 int maxdist
, bool task
)
1065 unsigned long score
= 0;
1069 * All nodes are directly connected, and the same distance
1070 * from each other. No need for fancy placement algorithms.
1072 if (sched_numa_topology_type
== NUMA_DIRECT
)
1076 * This code is called for each node, introducing N^2 complexity,
1077 * which should be ok given the number of nodes rarely exceeds 8.
1079 for_each_online_node(node
) {
1080 unsigned long faults
;
1081 int dist
= node_distance(nid
, node
);
1084 * The furthest away nodes in the system are not interesting
1085 * for placement; nid was already counted.
1087 if (dist
== sched_max_numa_distance
|| node
== nid
)
1091 * On systems with a backplane NUMA topology, compare groups
1092 * of nodes, and move tasks towards the group with the most
1093 * memory accesses. When comparing two nodes at distance
1094 * "hoplimit", only nodes closer by than "hoplimit" are part
1095 * of each group. Skip other nodes.
1097 if (sched_numa_topology_type
== NUMA_BACKPLANE
&&
1101 /* Add up the faults from nearby nodes. */
1103 faults
= task_faults(p
, node
);
1105 faults
= group_faults(p
, node
);
1108 * On systems with a glueless mesh NUMA topology, there are
1109 * no fixed "groups of nodes". Instead, nodes that are not
1110 * directly connected bounce traffic through intermediate
1111 * nodes; a numa_group can occupy any set of nodes.
1112 * The further away a node is, the less the faults count.
1113 * This seems to result in good task placement.
1115 if (sched_numa_topology_type
== NUMA_GLUELESS_MESH
) {
1116 faults
*= (sched_max_numa_distance
- dist
);
1117 faults
/= (sched_max_numa_distance
- LOCAL_DISTANCE
);
1127 * These return the fraction of accesses done by a particular task, or
1128 * task group, on a particular numa node. The group weight is given a
1129 * larger multiplier, in order to group tasks together that are almost
1130 * evenly spread out between numa nodes.
1132 static inline unsigned long task_weight(struct task_struct
*p
, int nid
,
1135 unsigned long faults
, total_faults
;
1137 if (!p
->numa_faults
)
1140 total_faults
= p
->total_numa_faults
;
1145 faults
= task_faults(p
, nid
);
1146 faults
+= score_nearby_nodes(p
, nid
, dist
, true);
1148 return 1000 * faults
/ total_faults
;
1151 static inline unsigned long group_weight(struct task_struct
*p
, int nid
,
1154 unsigned long faults
, total_faults
;
1159 total_faults
= p
->numa_group
->total_faults
;
1164 faults
= group_faults(p
, nid
);
1165 faults
+= score_nearby_nodes(p
, nid
, dist
, false);
1167 return 1000 * faults
/ total_faults
;
1170 bool should_numa_migrate_memory(struct task_struct
*p
, struct page
* page
,
1171 int src_nid
, int dst_cpu
)
1173 struct numa_group
*ng
= p
->numa_group
;
1174 int dst_nid
= cpu_to_node(dst_cpu
);
1175 int last_cpupid
, this_cpupid
;
1177 this_cpupid
= cpu_pid_to_cpupid(dst_cpu
, current
->pid
);
1180 * Multi-stage node selection is used in conjunction with a periodic
1181 * migration fault to build a temporal task<->page relation. By using
1182 * a two-stage filter we remove short/unlikely relations.
1184 * Using P(p) ~ n_p / n_t as per frequentist probability, we can equate
1185 * a task's usage of a particular page (n_p) per total usage of this
1186 * page (n_t) (in a given time-span) to a probability.
1188 * Our periodic faults will sample this probability and getting the
1189 * same result twice in a row, given these samples are fully
1190 * independent, is then given by P(n)^2, provided our sample period
1191 * is sufficiently short compared to the usage pattern.
1193 * This quadric squishes small probabilities, making it less likely we
1194 * act on an unlikely task<->page relation.
1196 last_cpupid
= page_cpupid_xchg_last(page
, this_cpupid
);
1197 if (!cpupid_pid_unset(last_cpupid
) &&
1198 cpupid_to_nid(last_cpupid
) != dst_nid
)
1201 /* Always allow migrate on private faults */
1202 if (cpupid_match_pid(p
, last_cpupid
))
1205 /* A shared fault, but p->numa_group has not been set up yet. */
1210 * Destination node is much more heavily used than the source
1211 * node? Allow migration.
1213 if (group_faults_cpu(ng
, dst_nid
) > group_faults_cpu(ng
, src_nid
) *
1214 ACTIVE_NODE_FRACTION
)
1218 * Distribute memory according to CPU & memory use on each node,
1219 * with 3/4 hysteresis to avoid unnecessary memory migrations:
1221 * faults_cpu(dst) 3 faults_cpu(src)
1222 * --------------- * - > ---------------
1223 * faults_mem(dst) 4 faults_mem(src)
1225 return group_faults_cpu(ng
, dst_nid
) * group_faults(p
, src_nid
) * 3 >
1226 group_faults_cpu(ng
, src_nid
) * group_faults(p
, dst_nid
) * 4;
1229 static unsigned long weighted_cpuload(const int cpu
);
1230 static unsigned long source_load(int cpu
, int type
);
1231 static unsigned long target_load(int cpu
, int type
);
1232 static unsigned long capacity_of(int cpu
);
1233 static long effective_load(struct task_group
*tg
, int cpu
, long wl
, long wg
);
1235 /* Cached statistics for all CPUs within a node */
1237 unsigned long nr_running
;
1240 /* Total compute capacity of CPUs on a node */
1241 unsigned long compute_capacity
;
1243 /* Approximate capacity in terms of runnable tasks on a node */
1244 unsigned long task_capacity
;
1245 int has_free_capacity
;
1249 * XXX borrowed from update_sg_lb_stats
1251 static void update_numa_stats(struct numa_stats
*ns
, int nid
)
1253 int smt
, cpu
, cpus
= 0;
1254 unsigned long capacity
;
1256 memset(ns
, 0, sizeof(*ns
));
1257 for_each_cpu(cpu
, cpumask_of_node(nid
)) {
1258 struct rq
*rq
= cpu_rq(cpu
);
1260 ns
->nr_running
+= rq
->nr_running
;
1261 ns
->load
+= weighted_cpuload(cpu
);
1262 ns
->compute_capacity
+= capacity_of(cpu
);
1268 * If we raced with hotplug and there are no CPUs left in our mask
1269 * the @ns structure is NULL'ed and task_numa_compare() will
1270 * not find this node attractive.
1272 * We'll either bail at !has_free_capacity, or we'll detect a huge
1273 * imbalance and bail there.
1278 /* smt := ceil(cpus / capacity), assumes: 1 < smt_power < 2 */
1279 smt
= DIV_ROUND_UP(SCHED_CAPACITY_SCALE
* cpus
, ns
->compute_capacity
);
1280 capacity
= cpus
/ smt
; /* cores */
1282 ns
->task_capacity
= min_t(unsigned, capacity
,
1283 DIV_ROUND_CLOSEST(ns
->compute_capacity
, SCHED_CAPACITY_SCALE
));
1284 ns
->has_free_capacity
= (ns
->nr_running
< ns
->task_capacity
);
1287 struct task_numa_env
{
1288 struct task_struct
*p
;
1290 int src_cpu
, src_nid
;
1291 int dst_cpu
, dst_nid
;
1293 struct numa_stats src_stats
, dst_stats
;
1298 struct task_struct
*best_task
;
1303 static void task_numa_assign(struct task_numa_env
*env
,
1304 struct task_struct
*p
, long imp
)
1307 put_task_struct(env
->best_task
);
1310 env
->best_imp
= imp
;
1311 env
->best_cpu
= env
->dst_cpu
;
1314 static bool load_too_imbalanced(long src_load
, long dst_load
,
1315 struct task_numa_env
*env
)
1318 long orig_src_load
, orig_dst_load
;
1319 long src_capacity
, dst_capacity
;
1322 * The load is corrected for the CPU capacity available on each node.
1325 * ------------ vs ---------
1326 * src_capacity dst_capacity
1328 src_capacity
= env
->src_stats
.compute_capacity
;
1329 dst_capacity
= env
->dst_stats
.compute_capacity
;
1331 /* We care about the slope of the imbalance, not the direction. */
1332 if (dst_load
< src_load
)
1333 swap(dst_load
, src_load
);
1335 /* Is the difference below the threshold? */
1336 imb
= dst_load
* src_capacity
* 100 -
1337 src_load
* dst_capacity
* env
->imbalance_pct
;
1342 * The imbalance is above the allowed threshold.
1343 * Compare it with the old imbalance.
1345 orig_src_load
= env
->src_stats
.load
;
1346 orig_dst_load
= env
->dst_stats
.load
;
1348 if (orig_dst_load
< orig_src_load
)
1349 swap(orig_dst_load
, orig_src_load
);
1351 old_imb
= orig_dst_load
* src_capacity
* 100 -
1352 orig_src_load
* dst_capacity
* env
->imbalance_pct
;
1354 /* Would this change make things worse? */
1355 return (imb
> old_imb
);
1359 * This checks if the overall compute and NUMA accesses of the system would
1360 * be improved if the source tasks was migrated to the target dst_cpu taking
1361 * into account that it might be best if task running on the dst_cpu should
1362 * be exchanged with the source task
1364 static void task_numa_compare(struct task_numa_env
*env
,
1365 long taskimp
, long groupimp
)
1367 struct rq
*src_rq
= cpu_rq(env
->src_cpu
);
1368 struct rq
*dst_rq
= cpu_rq(env
->dst_cpu
);
1369 struct task_struct
*cur
;
1370 long src_load
, dst_load
;
1372 long imp
= env
->p
->numa_group
? groupimp
: taskimp
;
1374 int dist
= env
->dist
;
1375 bool assigned
= false;
1379 raw_spin_lock_irq(&dst_rq
->lock
);
1382 * No need to move the exiting task or idle task.
1384 if ((cur
->flags
& PF_EXITING
) || is_idle_task(cur
))
1388 * The task_struct must be protected here to protect the
1389 * p->numa_faults access in the task_weight since the
1390 * numa_faults could already be freed in the following path:
1391 * finish_task_switch()
1392 * --> put_task_struct()
1393 * --> __put_task_struct()
1394 * --> task_numa_free()
1396 get_task_struct(cur
);
1399 raw_spin_unlock_irq(&dst_rq
->lock
);
1402 * Because we have preemption enabled we can get migrated around and
1403 * end try selecting ourselves (current == env->p) as a swap candidate.
1409 * "imp" is the fault differential for the source task between the
1410 * source and destination node. Calculate the total differential for
1411 * the source task and potential destination task. The more negative
1412 * the value is, the more rmeote accesses that would be expected to
1413 * be incurred if the tasks were swapped.
1416 /* Skip this swap candidate if cannot move to the source cpu */
1417 if (!cpumask_test_cpu(env
->src_cpu
, tsk_cpus_allowed(cur
)))
1421 * If dst and source tasks are in the same NUMA group, or not
1422 * in any group then look only at task weights.
1424 if (cur
->numa_group
== env
->p
->numa_group
) {
1425 imp
= taskimp
+ task_weight(cur
, env
->src_nid
, dist
) -
1426 task_weight(cur
, env
->dst_nid
, dist
);
1428 * Add some hysteresis to prevent swapping the
1429 * tasks within a group over tiny differences.
1431 if (cur
->numa_group
)
1435 * Compare the group weights. If a task is all by
1436 * itself (not part of a group), use the task weight
1439 if (cur
->numa_group
)
1440 imp
+= group_weight(cur
, env
->src_nid
, dist
) -
1441 group_weight(cur
, env
->dst_nid
, dist
);
1443 imp
+= task_weight(cur
, env
->src_nid
, dist
) -
1444 task_weight(cur
, env
->dst_nid
, dist
);
1448 if (imp
<= env
->best_imp
&& moveimp
<= env
->best_imp
)
1452 /* Is there capacity at our destination? */
1453 if (env
->src_stats
.nr_running
<= env
->src_stats
.task_capacity
&&
1454 !env
->dst_stats
.has_free_capacity
)
1460 /* Balance doesn't matter much if we're running a task per cpu */
1461 if (imp
> env
->best_imp
&& src_rq
->nr_running
== 1 &&
1462 dst_rq
->nr_running
== 1)
1466 * In the overloaded case, try and keep the load balanced.
1469 load
= task_h_load(env
->p
);
1470 dst_load
= env
->dst_stats
.load
+ load
;
1471 src_load
= env
->src_stats
.load
- load
;
1473 if (moveimp
> imp
&& moveimp
> env
->best_imp
) {
1475 * If the improvement from just moving env->p direction is
1476 * better than swapping tasks around, check if a move is
1477 * possible. Store a slightly smaller score than moveimp,
1478 * so an actually idle CPU will win.
1480 if (!load_too_imbalanced(src_load
, dst_load
, env
)) {
1482 put_task_struct(cur
);
1488 if (imp
<= env
->best_imp
)
1492 load
= task_h_load(cur
);
1497 if (load_too_imbalanced(src_load
, dst_load
, env
))
1501 * One idle CPU per node is evaluated for a task numa move.
1502 * Call select_idle_sibling to maybe find a better one.
1505 env
->dst_cpu
= select_idle_sibling(env
->p
, env
->dst_cpu
);
1509 task_numa_assign(env
, cur
, imp
);
1513 * The dst_rq->curr isn't assigned. The protection for task_struct is
1516 if (cur
&& !assigned
)
1517 put_task_struct(cur
);
1520 static void task_numa_find_cpu(struct task_numa_env
*env
,
1521 long taskimp
, long groupimp
)
1525 for_each_cpu(cpu
, cpumask_of_node(env
->dst_nid
)) {
1526 /* Skip this CPU if the source task cannot migrate */
1527 if (!cpumask_test_cpu(cpu
, tsk_cpus_allowed(env
->p
)))
1531 task_numa_compare(env
, taskimp
, groupimp
);
1535 /* Only move tasks to a NUMA node less busy than the current node. */
1536 static bool numa_has_capacity(struct task_numa_env
*env
)
1538 struct numa_stats
*src
= &env
->src_stats
;
1539 struct numa_stats
*dst
= &env
->dst_stats
;
1541 if (src
->has_free_capacity
&& !dst
->has_free_capacity
)
1545 * Only consider a task move if the source has a higher load
1546 * than the destination, corrected for CPU capacity on each node.
1548 * src->load dst->load
1549 * --------------------- vs ---------------------
1550 * src->compute_capacity dst->compute_capacity
1552 if (src
->load
* dst
->compute_capacity
* env
->imbalance_pct
>
1554 dst
->load
* src
->compute_capacity
* 100)
1560 static int task_numa_migrate(struct task_struct
*p
)
1562 struct task_numa_env env
= {
1565 .src_cpu
= task_cpu(p
),
1566 .src_nid
= task_node(p
),
1568 .imbalance_pct
= 112,
1574 struct sched_domain
*sd
;
1575 unsigned long taskweight
, groupweight
;
1577 long taskimp
, groupimp
;
1580 * Pick the lowest SD_NUMA domain, as that would have the smallest
1581 * imbalance and would be the first to start moving tasks about.
1583 * And we want to avoid any moving of tasks about, as that would create
1584 * random movement of tasks -- counter the numa conditions we're trying
1588 sd
= rcu_dereference(per_cpu(sd_numa
, env
.src_cpu
));
1590 env
.imbalance_pct
= 100 + (sd
->imbalance_pct
- 100) / 2;
1594 * Cpusets can break the scheduler domain tree into smaller
1595 * balance domains, some of which do not cross NUMA boundaries.
1596 * Tasks that are "trapped" in such domains cannot be migrated
1597 * elsewhere, so there is no point in (re)trying.
1599 if (unlikely(!sd
)) {
1600 p
->numa_preferred_nid
= task_node(p
);
1604 env
.dst_nid
= p
->numa_preferred_nid
;
1605 dist
= env
.dist
= node_distance(env
.src_nid
, env
.dst_nid
);
1606 taskweight
= task_weight(p
, env
.src_nid
, dist
);
1607 groupweight
= group_weight(p
, env
.src_nid
, dist
);
1608 update_numa_stats(&env
.src_stats
, env
.src_nid
);
1609 taskimp
= task_weight(p
, env
.dst_nid
, dist
) - taskweight
;
1610 groupimp
= group_weight(p
, env
.dst_nid
, dist
) - groupweight
;
1611 update_numa_stats(&env
.dst_stats
, env
.dst_nid
);
1613 /* Try to find a spot on the preferred nid. */
1614 if (numa_has_capacity(&env
))
1615 task_numa_find_cpu(&env
, taskimp
, groupimp
);
1618 * Look at other nodes in these cases:
1619 * - there is no space available on the preferred_nid
1620 * - the task is part of a numa_group that is interleaved across
1621 * multiple NUMA nodes; in order to better consolidate the group,
1622 * we need to check other locations.
1624 if (env
.best_cpu
== -1 || (p
->numa_group
&& p
->numa_group
->active_nodes
> 1)) {
1625 for_each_online_node(nid
) {
1626 if (nid
== env
.src_nid
|| nid
== p
->numa_preferred_nid
)
1629 dist
= node_distance(env
.src_nid
, env
.dst_nid
);
1630 if (sched_numa_topology_type
== NUMA_BACKPLANE
&&
1632 taskweight
= task_weight(p
, env
.src_nid
, dist
);
1633 groupweight
= group_weight(p
, env
.src_nid
, dist
);
1636 /* Only consider nodes where both task and groups benefit */
1637 taskimp
= task_weight(p
, nid
, dist
) - taskweight
;
1638 groupimp
= group_weight(p
, nid
, dist
) - groupweight
;
1639 if (taskimp
< 0 && groupimp
< 0)
1644 update_numa_stats(&env
.dst_stats
, env
.dst_nid
);
1645 if (numa_has_capacity(&env
))
1646 task_numa_find_cpu(&env
, taskimp
, groupimp
);
1651 * If the task is part of a workload that spans multiple NUMA nodes,
1652 * and is migrating into one of the workload's active nodes, remember
1653 * this node as the task's preferred numa node, so the workload can
1655 * A task that migrated to a second choice node will be better off
1656 * trying for a better one later. Do not set the preferred node here.
1658 if (p
->numa_group
) {
1659 struct numa_group
*ng
= p
->numa_group
;
1661 if (env
.best_cpu
== -1)
1666 if (ng
->active_nodes
> 1 && numa_is_active_node(env
.dst_nid
, ng
))
1667 sched_setnuma(p
, env
.dst_nid
);
1670 /* No better CPU than the current one was found. */
1671 if (env
.best_cpu
== -1)
1675 * Reset the scan period if the task is being rescheduled on an
1676 * alternative node to recheck if the tasks is now properly placed.
1678 p
->numa_scan_period
= task_scan_min(p
);
1680 if (env
.best_task
== NULL
) {
1681 ret
= migrate_task_to(p
, env
.best_cpu
);
1683 trace_sched_stick_numa(p
, env
.src_cpu
, env
.best_cpu
);
1687 ret
= migrate_swap(p
, env
.best_task
);
1689 trace_sched_stick_numa(p
, env
.src_cpu
, task_cpu(env
.best_task
));
1690 put_task_struct(env
.best_task
);
1694 /* Attempt to migrate a task to a CPU on the preferred node. */
1695 static void numa_migrate_preferred(struct task_struct
*p
)
1697 unsigned long interval
= HZ
;
1699 /* This task has no NUMA fault statistics yet */
1700 if (unlikely(p
->numa_preferred_nid
== -1 || !p
->numa_faults
))
1703 /* Periodically retry migrating the task to the preferred node */
1704 interval
= min(interval
, msecs_to_jiffies(p
->numa_scan_period
) / 16);
1705 p
->numa_migrate_retry
= jiffies
+ interval
;
1707 /* Success if task is already running on preferred CPU */
1708 if (task_node(p
) == p
->numa_preferred_nid
)
1711 /* Otherwise, try migrate to a CPU on the preferred node */
1712 task_numa_migrate(p
);
1716 * Find out how many nodes on the workload is actively running on. Do this by
1717 * tracking the nodes from which NUMA hinting faults are triggered. This can
1718 * be different from the set of nodes where the workload's memory is currently
1721 static void numa_group_count_active_nodes(struct numa_group
*numa_group
)
1723 unsigned long faults
, max_faults
= 0;
1724 int nid
, active_nodes
= 0;
1726 for_each_online_node(nid
) {
1727 faults
= group_faults_cpu(numa_group
, nid
);
1728 if (faults
> max_faults
)
1729 max_faults
= faults
;
1732 for_each_online_node(nid
) {
1733 faults
= group_faults_cpu(numa_group
, nid
);
1734 if (faults
* ACTIVE_NODE_FRACTION
> max_faults
)
1738 numa_group
->max_faults_cpu
= max_faults
;
1739 numa_group
->active_nodes
= active_nodes
;
1743 * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS
1744 * increments. The more local the fault statistics are, the higher the scan
1745 * period will be for the next scan window. If local/(local+remote) ratio is
1746 * below NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS)
1747 * the scan period will decrease. Aim for 70% local accesses.
1749 #define NUMA_PERIOD_SLOTS 10
1750 #define NUMA_PERIOD_THRESHOLD 7
1753 * Increase the scan period (slow down scanning) if the majority of
1754 * our memory is already on our local node, or if the majority of
1755 * the page accesses are shared with other processes.
1756 * Otherwise, decrease the scan period.
1758 static void update_task_scan_period(struct task_struct
*p
,
1759 unsigned long shared
, unsigned long private)
1761 unsigned int period_slot
;
1765 unsigned long remote
= p
->numa_faults_locality
[0];
1766 unsigned long local
= p
->numa_faults_locality
[1];
1769 * If there were no record hinting faults then either the task is
1770 * completely idle or all activity is areas that are not of interest
1771 * to automatic numa balancing. Related to that, if there were failed
1772 * migration then it implies we are migrating too quickly or the local
1773 * node is overloaded. In either case, scan slower
1775 if (local
+ shared
== 0 || p
->numa_faults_locality
[2]) {
1776 p
->numa_scan_period
= min(p
->numa_scan_period_max
,
1777 p
->numa_scan_period
<< 1);
1779 p
->mm
->numa_next_scan
= jiffies
+
1780 msecs_to_jiffies(p
->numa_scan_period
);
1786 * Prepare to scale scan period relative to the current period.
1787 * == NUMA_PERIOD_THRESHOLD scan period stays the same
1788 * < NUMA_PERIOD_THRESHOLD scan period decreases (scan faster)
1789 * >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower)
1791 period_slot
= DIV_ROUND_UP(p
->numa_scan_period
, NUMA_PERIOD_SLOTS
);
1792 ratio
= (local
* NUMA_PERIOD_SLOTS
) / (local
+ remote
);
1793 if (ratio
>= NUMA_PERIOD_THRESHOLD
) {
1794 int slot
= ratio
- NUMA_PERIOD_THRESHOLD
;
1797 diff
= slot
* period_slot
;
1799 diff
= -(NUMA_PERIOD_THRESHOLD
- ratio
) * period_slot
;
1802 * Scale scan rate increases based on sharing. There is an
1803 * inverse relationship between the degree of sharing and
1804 * the adjustment made to the scanning period. Broadly
1805 * speaking the intent is that there is little point
1806 * scanning faster if shared accesses dominate as it may
1807 * simply bounce migrations uselessly
1809 ratio
= DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS
, (private + shared
+ 1));
1810 diff
= (diff
* ratio
) / NUMA_PERIOD_SLOTS
;
1813 p
->numa_scan_period
= clamp(p
->numa_scan_period
+ diff
,
1814 task_scan_min(p
), task_scan_max(p
));
1815 memset(p
->numa_faults_locality
, 0, sizeof(p
->numa_faults_locality
));
1819 * Get the fraction of time the task has been running since the last
1820 * NUMA placement cycle. The scheduler keeps similar statistics, but
1821 * decays those on a 32ms period, which is orders of magnitude off
1822 * from the dozens-of-seconds NUMA balancing period. Use the scheduler
1823 * stats only if the task is so new there are no NUMA statistics yet.
1825 static u64
numa_get_avg_runtime(struct task_struct
*p
, u64
*period
)
1827 u64 runtime
, delta
, now
;
1828 /* Use the start of this time slice to avoid calculations. */
1829 now
= p
->se
.exec_start
;
1830 runtime
= p
->se
.sum_exec_runtime
;
1832 if (p
->last_task_numa_placement
) {
1833 delta
= runtime
- p
->last_sum_exec_runtime
;
1834 *period
= now
- p
->last_task_numa_placement
;
1836 delta
= p
->se
.avg
.load_sum
/ p
->se
.load
.weight
;
1837 *period
= LOAD_AVG_MAX
;
1840 p
->last_sum_exec_runtime
= runtime
;
1841 p
->last_task_numa_placement
= now
;
1847 * Determine the preferred nid for a task in a numa_group. This needs to
1848 * be done in a way that produces consistent results with group_weight,
1849 * otherwise workloads might not converge.
1851 static int preferred_group_nid(struct task_struct
*p
, int nid
)
1856 /* Direct connections between all NUMA nodes. */
1857 if (sched_numa_topology_type
== NUMA_DIRECT
)
1861 * On a system with glueless mesh NUMA topology, group_weight
1862 * scores nodes according to the number of NUMA hinting faults on
1863 * both the node itself, and on nearby nodes.
1865 if (sched_numa_topology_type
== NUMA_GLUELESS_MESH
) {
1866 unsigned long score
, max_score
= 0;
1867 int node
, max_node
= nid
;
1869 dist
= sched_max_numa_distance
;
1871 for_each_online_node(node
) {
1872 score
= group_weight(p
, node
, dist
);
1873 if (score
> max_score
) {
1882 * Finding the preferred nid in a system with NUMA backplane
1883 * interconnect topology is more involved. The goal is to locate
1884 * tasks from numa_groups near each other in the system, and
1885 * untangle workloads from different sides of the system. This requires
1886 * searching down the hierarchy of node groups, recursively searching
1887 * inside the highest scoring group of nodes. The nodemask tricks
1888 * keep the complexity of the search down.
1890 nodes
= node_online_map
;
1891 for (dist
= sched_max_numa_distance
; dist
> LOCAL_DISTANCE
; dist
--) {
1892 unsigned long max_faults
= 0;
1893 nodemask_t max_group
= NODE_MASK_NONE
;
1896 /* Are there nodes at this distance from each other? */
1897 if (!find_numa_distance(dist
))
1900 for_each_node_mask(a
, nodes
) {
1901 unsigned long faults
= 0;
1902 nodemask_t this_group
;
1903 nodes_clear(this_group
);
1905 /* Sum group's NUMA faults; includes a==b case. */
1906 for_each_node_mask(b
, nodes
) {
1907 if (node_distance(a
, b
) < dist
) {
1908 faults
+= group_faults(p
, b
);
1909 node_set(b
, this_group
);
1910 node_clear(b
, nodes
);
1914 /* Remember the top group. */
1915 if (faults
> max_faults
) {
1916 max_faults
= faults
;
1917 max_group
= this_group
;
1919 * subtle: at the smallest distance there is
1920 * just one node left in each "group", the
1921 * winner is the preferred nid.
1926 /* Next round, evaluate the nodes within max_group. */
1934 static void task_numa_placement(struct task_struct
*p
)
1936 int seq
, nid
, max_nid
= -1, max_group_nid
= -1;
1937 unsigned long max_faults
= 0, max_group_faults
= 0;
1938 unsigned long fault_types
[2] = { 0, 0 };
1939 unsigned long total_faults
;
1940 u64 runtime
, period
;
1941 spinlock_t
*group_lock
= NULL
;
1944 * The p->mm->numa_scan_seq field gets updated without
1945 * exclusive access. Use READ_ONCE() here to ensure
1946 * that the field is read in a single access:
1948 seq
= READ_ONCE(p
->mm
->numa_scan_seq
);
1949 if (p
->numa_scan_seq
== seq
)
1951 p
->numa_scan_seq
= seq
;
1952 p
->numa_scan_period_max
= task_scan_max(p
);
1954 total_faults
= p
->numa_faults_locality
[0] +
1955 p
->numa_faults_locality
[1];
1956 runtime
= numa_get_avg_runtime(p
, &period
);
1958 /* If the task is part of a group prevent parallel updates to group stats */
1959 if (p
->numa_group
) {
1960 group_lock
= &p
->numa_group
->lock
;
1961 spin_lock_irq(group_lock
);
1964 /* Find the node with the highest number of faults */
1965 for_each_online_node(nid
) {
1966 /* Keep track of the offsets in numa_faults array */
1967 int mem_idx
, membuf_idx
, cpu_idx
, cpubuf_idx
;
1968 unsigned long faults
= 0, group_faults
= 0;
1971 for (priv
= 0; priv
< NR_NUMA_HINT_FAULT_TYPES
; priv
++) {
1972 long diff
, f_diff
, f_weight
;
1974 mem_idx
= task_faults_idx(NUMA_MEM
, nid
, priv
);
1975 membuf_idx
= task_faults_idx(NUMA_MEMBUF
, nid
, priv
);
1976 cpu_idx
= task_faults_idx(NUMA_CPU
, nid
, priv
);
1977 cpubuf_idx
= task_faults_idx(NUMA_CPUBUF
, nid
, priv
);
1979 /* Decay existing window, copy faults since last scan */
1980 diff
= p
->numa_faults
[membuf_idx
] - p
->numa_faults
[mem_idx
] / 2;
1981 fault_types
[priv
] += p
->numa_faults
[membuf_idx
];
1982 p
->numa_faults
[membuf_idx
] = 0;
1985 * Normalize the faults_from, so all tasks in a group
1986 * count according to CPU use, instead of by the raw
1987 * number of faults. Tasks with little runtime have
1988 * little over-all impact on throughput, and thus their
1989 * faults are less important.
1991 f_weight
= div64_u64(runtime
<< 16, period
+ 1);
1992 f_weight
= (f_weight
* p
->numa_faults
[cpubuf_idx
]) /
1994 f_diff
= f_weight
- p
->numa_faults
[cpu_idx
] / 2;
1995 p
->numa_faults
[cpubuf_idx
] = 0;
1997 p
->numa_faults
[mem_idx
] += diff
;
1998 p
->numa_faults
[cpu_idx
] += f_diff
;
1999 faults
+= p
->numa_faults
[mem_idx
];
2000 p
->total_numa_faults
+= diff
;
2001 if (p
->numa_group
) {
2003 * safe because we can only change our own group
2005 * mem_idx represents the offset for a given
2006 * nid and priv in a specific region because it
2007 * is at the beginning of the numa_faults array.
2009 p
->numa_group
->faults
[mem_idx
] += diff
;
2010 p
->numa_group
->faults_cpu
[mem_idx
] += f_diff
;
2011 p
->numa_group
->total_faults
+= diff
;
2012 group_faults
+= p
->numa_group
->faults
[mem_idx
];
2016 if (faults
> max_faults
) {
2017 max_faults
= faults
;
2021 if (group_faults
> max_group_faults
) {
2022 max_group_faults
= group_faults
;
2023 max_group_nid
= nid
;
2027 update_task_scan_period(p
, fault_types
[0], fault_types
[1]);
2029 if (p
->numa_group
) {
2030 numa_group_count_active_nodes(p
->numa_group
);
2031 spin_unlock_irq(group_lock
);
2032 max_nid
= preferred_group_nid(p
, max_group_nid
);
2036 /* Set the new preferred node */
2037 if (max_nid
!= p
->numa_preferred_nid
)
2038 sched_setnuma(p
, max_nid
);
2040 if (task_node(p
) != p
->numa_preferred_nid
)
2041 numa_migrate_preferred(p
);
2045 static inline int get_numa_group(struct numa_group
*grp
)
2047 return atomic_inc_not_zero(&grp
->refcount
);
2050 static inline void put_numa_group(struct numa_group
*grp
)
2052 if (atomic_dec_and_test(&grp
->refcount
))
2053 kfree_rcu(grp
, rcu
);
2056 static void task_numa_group(struct task_struct
*p
, int cpupid
, int flags
,
2059 struct numa_group
*grp
, *my_grp
;
2060 struct task_struct
*tsk
;
2062 int cpu
= cpupid_to_cpu(cpupid
);
2065 if (unlikely(!p
->numa_group
)) {
2066 unsigned int size
= sizeof(struct numa_group
) +
2067 4*nr_node_ids
*sizeof(unsigned long);
2069 grp
= kzalloc(size
, GFP_KERNEL
| __GFP_NOWARN
);
2073 atomic_set(&grp
->refcount
, 1);
2074 grp
->active_nodes
= 1;
2075 grp
->max_faults_cpu
= 0;
2076 spin_lock_init(&grp
->lock
);
2078 /* Second half of the array tracks nids where faults happen */
2079 grp
->faults_cpu
= grp
->faults
+ NR_NUMA_HINT_FAULT_TYPES
*
2082 for (i
= 0; i
< NR_NUMA_HINT_FAULT_STATS
* nr_node_ids
; i
++)
2083 grp
->faults
[i
] = p
->numa_faults
[i
];
2085 grp
->total_faults
= p
->total_numa_faults
;
2088 rcu_assign_pointer(p
->numa_group
, grp
);
2092 tsk
= READ_ONCE(cpu_rq(cpu
)->curr
);
2094 if (!cpupid_match_pid(tsk
, cpupid
))
2097 grp
= rcu_dereference(tsk
->numa_group
);
2101 my_grp
= p
->numa_group
;
2106 * Only join the other group if its bigger; if we're the bigger group,
2107 * the other task will join us.
2109 if (my_grp
->nr_tasks
> grp
->nr_tasks
)
2113 * Tie-break on the grp address.
2115 if (my_grp
->nr_tasks
== grp
->nr_tasks
&& my_grp
> grp
)
2118 /* Always join threads in the same process. */
2119 if (tsk
->mm
== current
->mm
)
2122 /* Simple filter to avoid false positives due to PID collisions */
2123 if (flags
& TNF_SHARED
)
2126 /* Update priv based on whether false sharing was detected */
2129 if (join
&& !get_numa_group(grp
))
2137 BUG_ON(irqs_disabled());
2138 double_lock_irq(&my_grp
->lock
, &grp
->lock
);
2140 for (i
= 0; i
< NR_NUMA_HINT_FAULT_STATS
* nr_node_ids
; i
++) {
2141 my_grp
->faults
[i
] -= p
->numa_faults
[i
];
2142 grp
->faults
[i
] += p
->numa_faults
[i
];
2144 my_grp
->total_faults
-= p
->total_numa_faults
;
2145 grp
->total_faults
+= p
->total_numa_faults
;
2150 spin_unlock(&my_grp
->lock
);
2151 spin_unlock_irq(&grp
->lock
);
2153 rcu_assign_pointer(p
->numa_group
, grp
);
2155 put_numa_group(my_grp
);
2163 void task_numa_free(struct task_struct
*p
)
2165 struct numa_group
*grp
= p
->numa_group
;
2166 void *numa_faults
= p
->numa_faults
;
2167 unsigned long flags
;
2171 spin_lock_irqsave(&grp
->lock
, flags
);
2172 for (i
= 0; i
< NR_NUMA_HINT_FAULT_STATS
* nr_node_ids
; i
++)
2173 grp
->faults
[i
] -= p
->numa_faults
[i
];
2174 grp
->total_faults
-= p
->total_numa_faults
;
2177 spin_unlock_irqrestore(&grp
->lock
, flags
);
2178 RCU_INIT_POINTER(p
->numa_group
, NULL
);
2179 put_numa_group(grp
);
2182 p
->numa_faults
= NULL
;
2187 * Got a PROT_NONE fault for a page on @node.
2189 void task_numa_fault(int last_cpupid
, int mem_node
, int pages
, int flags
)
2191 struct task_struct
*p
= current
;
2192 bool migrated
= flags
& TNF_MIGRATED
;
2193 int cpu_node
= task_node(current
);
2194 int local
= !!(flags
& TNF_FAULT_LOCAL
);
2195 struct numa_group
*ng
;
2198 if (!static_branch_likely(&sched_numa_balancing
))
2201 /* for example, ksmd faulting in a user's mm */
2205 /* Allocate buffer to track faults on a per-node basis */
2206 if (unlikely(!p
->numa_faults
)) {
2207 int size
= sizeof(*p
->numa_faults
) *
2208 NR_NUMA_HINT_FAULT_BUCKETS
* nr_node_ids
;
2210 p
->numa_faults
= kzalloc(size
, GFP_KERNEL
|__GFP_NOWARN
);
2211 if (!p
->numa_faults
)
2214 p
->total_numa_faults
= 0;
2215 memset(p
->numa_faults_locality
, 0, sizeof(p
->numa_faults_locality
));
2219 * First accesses are treated as private, otherwise consider accesses
2220 * to be private if the accessing pid has not changed
2222 if (unlikely(last_cpupid
== (-1 & LAST_CPUPID_MASK
))) {
2225 priv
= cpupid_match_pid(p
, last_cpupid
);
2226 if (!priv
&& !(flags
& TNF_NO_GROUP
))
2227 task_numa_group(p
, last_cpupid
, flags
, &priv
);
2231 * If a workload spans multiple NUMA nodes, a shared fault that
2232 * occurs wholly within the set of nodes that the workload is
2233 * actively using should be counted as local. This allows the
2234 * scan rate to slow down when a workload has settled down.
2237 if (!priv
&& !local
&& ng
&& ng
->active_nodes
> 1 &&
2238 numa_is_active_node(cpu_node
, ng
) &&
2239 numa_is_active_node(mem_node
, ng
))
2242 task_numa_placement(p
);
2245 * Retry task to preferred node migration periodically, in case it
2246 * case it previously failed, or the scheduler moved us.
2248 if (time_after(jiffies
, p
->numa_migrate_retry
))
2249 numa_migrate_preferred(p
);
2252 p
->numa_pages_migrated
+= pages
;
2253 if (flags
& TNF_MIGRATE_FAIL
)
2254 p
->numa_faults_locality
[2] += pages
;
2256 p
->numa_faults
[task_faults_idx(NUMA_MEMBUF
, mem_node
, priv
)] += pages
;
2257 p
->numa_faults
[task_faults_idx(NUMA_CPUBUF
, cpu_node
, priv
)] += pages
;
2258 p
->numa_faults_locality
[local
] += pages
;
2261 static void reset_ptenuma_scan(struct task_struct
*p
)
2264 * We only did a read acquisition of the mmap sem, so
2265 * p->mm->numa_scan_seq is written to without exclusive access
2266 * and the update is not guaranteed to be atomic. That's not
2267 * much of an issue though, since this is just used for
2268 * statistical sampling. Use READ_ONCE/WRITE_ONCE, which are not
2269 * expensive, to avoid any form of compiler optimizations:
2271 WRITE_ONCE(p
->mm
->numa_scan_seq
, READ_ONCE(p
->mm
->numa_scan_seq
) + 1);
2272 p
->mm
->numa_scan_offset
= 0;
2276 * The expensive part of numa migration is done from task_work context.
2277 * Triggered from task_tick_numa().
2279 void task_numa_work(struct callback_head
*work
)
2281 unsigned long migrate
, next_scan
, now
= jiffies
;
2282 struct task_struct
*p
= current
;
2283 struct mm_struct
*mm
= p
->mm
;
2284 u64 runtime
= p
->se
.sum_exec_runtime
;
2285 struct vm_area_struct
*vma
;
2286 unsigned long start
, end
;
2287 unsigned long nr_pte_updates
= 0;
2288 long pages
, virtpages
;
2290 WARN_ON_ONCE(p
!= container_of(work
, struct task_struct
, numa_work
));
2292 work
->next
= work
; /* protect against double add */
2294 * Who cares about NUMA placement when they're dying.
2296 * NOTE: make sure not to dereference p->mm before this check,
2297 * exit_task_work() happens _after_ exit_mm() so we could be called
2298 * without p->mm even though we still had it when we enqueued this
2301 if (p
->flags
& PF_EXITING
)
2304 if (!mm
->numa_next_scan
) {
2305 mm
->numa_next_scan
= now
+
2306 msecs_to_jiffies(sysctl_numa_balancing_scan_delay
);
2310 * Enforce maximal scan/migration frequency..
2312 migrate
= mm
->numa_next_scan
;
2313 if (time_before(now
, migrate
))
2316 if (p
->numa_scan_period
== 0) {
2317 p
->numa_scan_period_max
= task_scan_max(p
);
2318 p
->numa_scan_period
= task_scan_min(p
);
2321 next_scan
= now
+ msecs_to_jiffies(p
->numa_scan_period
);
2322 if (cmpxchg(&mm
->numa_next_scan
, migrate
, next_scan
) != migrate
)
2326 * Delay this task enough that another task of this mm will likely win
2327 * the next time around.
2329 p
->node_stamp
+= 2 * TICK_NSEC
;
2331 start
= mm
->numa_scan_offset
;
2332 pages
= sysctl_numa_balancing_scan_size
;
2333 pages
<<= 20 - PAGE_SHIFT
; /* MB in pages */
2334 virtpages
= pages
* 8; /* Scan up to this much virtual space */
2339 down_read(&mm
->mmap_sem
);
2340 vma
= find_vma(mm
, start
);
2342 reset_ptenuma_scan(p
);
2346 for (; vma
; vma
= vma
->vm_next
) {
2347 if (!vma_migratable(vma
) || !vma_policy_mof(vma
) ||
2348 is_vm_hugetlb_page(vma
) || (vma
->vm_flags
& VM_MIXEDMAP
)) {
2353 * Shared library pages mapped by multiple processes are not
2354 * migrated as it is expected they are cache replicated. Avoid
2355 * hinting faults in read-only file-backed mappings or the vdso
2356 * as migrating the pages will be of marginal benefit.
2359 (vma
->vm_file
&& (vma
->vm_flags
& (VM_READ
|VM_WRITE
)) == (VM_READ
)))
2363 * Skip inaccessible VMAs to avoid any confusion between
2364 * PROT_NONE and NUMA hinting ptes
2366 if (!(vma
->vm_flags
& (VM_READ
| VM_EXEC
| VM_WRITE
)))
2370 start
= max(start
, vma
->vm_start
);
2371 end
= ALIGN(start
+ (pages
<< PAGE_SHIFT
), HPAGE_SIZE
);
2372 end
= min(end
, vma
->vm_end
);
2373 nr_pte_updates
= change_prot_numa(vma
, start
, end
);
2376 * Try to scan sysctl_numa_balancing_size worth of
2377 * hpages that have at least one present PTE that
2378 * is not already pte-numa. If the VMA contains
2379 * areas that are unused or already full of prot_numa
2380 * PTEs, scan up to virtpages, to skip through those
2384 pages
-= (end
- start
) >> PAGE_SHIFT
;
2385 virtpages
-= (end
- start
) >> PAGE_SHIFT
;
2388 if (pages
<= 0 || virtpages
<= 0)
2392 } while (end
!= vma
->vm_end
);
2397 * It is possible to reach the end of the VMA list but the last few
2398 * VMAs are not guaranteed to the vma_migratable. If they are not, we
2399 * would find the !migratable VMA on the next scan but not reset the
2400 * scanner to the start so check it now.
2403 mm
->numa_scan_offset
= start
;
2405 reset_ptenuma_scan(p
);
2406 up_read(&mm
->mmap_sem
);
2409 * Make sure tasks use at least 32x as much time to run other code
2410 * than they used here, to limit NUMA PTE scanning overhead to 3% max.
2411 * Usually update_task_scan_period slows down scanning enough; on an
2412 * overloaded system we need to limit overhead on a per task basis.
2414 if (unlikely(p
->se
.sum_exec_runtime
!= runtime
)) {
2415 u64 diff
= p
->se
.sum_exec_runtime
- runtime
;
2416 p
->node_stamp
+= 32 * diff
;
2421 * Drive the periodic memory faults..
2423 void task_tick_numa(struct rq
*rq
, struct task_struct
*curr
)
2425 struct callback_head
*work
= &curr
->numa_work
;
2429 * We don't care about NUMA placement if we don't have memory.
2431 if (!curr
->mm
|| (curr
->flags
& PF_EXITING
) || work
->next
!= work
)
2435 * Using runtime rather than walltime has the dual advantage that
2436 * we (mostly) drive the selection from busy threads and that the
2437 * task needs to have done some actual work before we bother with
2440 now
= curr
->se
.sum_exec_runtime
;
2441 period
= (u64
)curr
->numa_scan_period
* NSEC_PER_MSEC
;
2443 if (now
> curr
->node_stamp
+ period
) {
2444 if (!curr
->node_stamp
)
2445 curr
->numa_scan_period
= task_scan_min(curr
);
2446 curr
->node_stamp
+= period
;
2448 if (!time_before(jiffies
, curr
->mm
->numa_next_scan
)) {
2449 init_task_work(work
, task_numa_work
); /* TODO: move this into sched_fork() */
2450 task_work_add(curr
, work
, true);
2455 static void task_tick_numa(struct rq
*rq
, struct task_struct
*curr
)
2459 static inline void account_numa_enqueue(struct rq
*rq
, struct task_struct
*p
)
2463 static inline void account_numa_dequeue(struct rq
*rq
, struct task_struct
*p
)
2466 #endif /* CONFIG_NUMA_BALANCING */
2469 account_entity_enqueue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
2471 update_load_add(&cfs_rq
->load
, se
->load
.weight
);
2472 if (!parent_entity(se
))
2473 update_load_add(&rq_of(cfs_rq
)->load
, se
->load
.weight
);
2475 if (entity_is_task(se
)) {
2476 struct rq
*rq
= rq_of(cfs_rq
);
2478 account_numa_enqueue(rq
, task_of(se
));
2479 list_add(&se
->group_node
, &rq
->cfs_tasks
);
2482 cfs_rq
->nr_running
++;
2486 account_entity_dequeue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
2488 update_load_sub(&cfs_rq
->load
, se
->load
.weight
);
2489 if (!parent_entity(se
))
2490 update_load_sub(&rq_of(cfs_rq
)->load
, se
->load
.weight
);
2492 if (entity_is_task(se
)) {
2493 account_numa_dequeue(rq_of(cfs_rq
), task_of(se
));
2494 list_del_init(&se
->group_node
);
2497 cfs_rq
->nr_running
--;
2500 #ifdef CONFIG_FAIR_GROUP_SCHED
2502 static inline long calc_tg_weight(struct task_group
*tg
, struct cfs_rq
*cfs_rq
)
2507 * Use this CPU's real-time load instead of the last load contribution
2508 * as the updating of the contribution is delayed, and we will use the
2509 * the real-time load to calc the share. See update_tg_load_avg().
2511 tg_weight
= atomic_long_read(&tg
->load_avg
);
2512 tg_weight
-= cfs_rq
->tg_load_avg_contrib
;
2513 tg_weight
+= cfs_rq
->load
.weight
;
2518 static long calc_cfs_shares(struct cfs_rq
*cfs_rq
, struct task_group
*tg
)
2520 long tg_weight
, load
, shares
;
2522 tg_weight
= calc_tg_weight(tg
, cfs_rq
);
2523 load
= cfs_rq
->load
.weight
;
2525 shares
= (tg
->shares
* load
);
2527 shares
/= tg_weight
;
2529 if (shares
< MIN_SHARES
)
2530 shares
= MIN_SHARES
;
2531 if (shares
> tg
->shares
)
2532 shares
= tg
->shares
;
2536 # else /* CONFIG_SMP */
2537 static inline long calc_cfs_shares(struct cfs_rq
*cfs_rq
, struct task_group
*tg
)
2541 # endif /* CONFIG_SMP */
2542 static void reweight_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
,
2543 unsigned long weight
)
2546 /* commit outstanding execution time */
2547 if (cfs_rq
->curr
== se
)
2548 update_curr(cfs_rq
);
2549 account_entity_dequeue(cfs_rq
, se
);
2552 update_load_set(&se
->load
, weight
);
2555 account_entity_enqueue(cfs_rq
, se
);
2558 static inline int throttled_hierarchy(struct cfs_rq
*cfs_rq
);
2560 static void update_cfs_shares(struct cfs_rq
*cfs_rq
)
2562 struct task_group
*tg
;
2563 struct sched_entity
*se
;
2567 se
= tg
->se
[cpu_of(rq_of(cfs_rq
))];
2568 if (!se
|| throttled_hierarchy(cfs_rq
))
2571 if (likely(se
->load
.weight
== tg
->shares
))
2574 shares
= calc_cfs_shares(cfs_rq
, tg
);
2576 reweight_entity(cfs_rq_of(se
), se
, shares
);
2578 #else /* CONFIG_FAIR_GROUP_SCHED */
2579 static inline void update_cfs_shares(struct cfs_rq
*cfs_rq
)
2582 #endif /* CONFIG_FAIR_GROUP_SCHED */
2585 /* Precomputed fixed inverse multiplies for multiplication by y^n */
2586 static const u32 runnable_avg_yN_inv
[] = {
2587 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6,
2588 0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85,
2589 0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581,
2590 0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9,
2591 0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80,
2592 0x85aac367, 0x82cd8698,
2596 * Precomputed \Sum y^k { 1<=k<=n }. These are floor(true_value) to prevent
2597 * over-estimates when re-combining.
2599 static const u32 runnable_avg_yN_sum
[] = {
2600 0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103,
2601 9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082,
2602 17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371,
2607 * val * y^n, where y^32 ~= 0.5 (~1 scheduling period)
2609 static __always_inline u64
decay_load(u64 val
, u64 n
)
2611 unsigned int local_n
;
2615 else if (unlikely(n
> LOAD_AVG_PERIOD
* 63))
2618 /* after bounds checking we can collapse to 32-bit */
2622 * As y^PERIOD = 1/2, we can combine
2623 * y^n = 1/2^(n/PERIOD) * y^(n%PERIOD)
2624 * With a look-up table which covers y^n (n<PERIOD)
2626 * To achieve constant time decay_load.
2628 if (unlikely(local_n
>= LOAD_AVG_PERIOD
)) {
2629 val
>>= local_n
/ LOAD_AVG_PERIOD
;
2630 local_n
%= LOAD_AVG_PERIOD
;
2633 val
= mul_u64_u32_shr(val
, runnable_avg_yN_inv
[local_n
], 32);
2638 * For updates fully spanning n periods, the contribution to runnable
2639 * average will be: \Sum 1024*y^n
2641 * We can compute this reasonably efficiently by combining:
2642 * y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for n <PERIOD}
2644 static u32
__compute_runnable_contrib(u64 n
)
2648 if (likely(n
<= LOAD_AVG_PERIOD
))
2649 return runnable_avg_yN_sum
[n
];
2650 else if (unlikely(n
>= LOAD_AVG_MAX_N
))
2651 return LOAD_AVG_MAX
;
2653 /* Compute \Sum k^n combining precomputed values for k^i, \Sum k^j */
2655 contrib
/= 2; /* y^LOAD_AVG_PERIOD = 1/2 */
2656 contrib
+= runnable_avg_yN_sum
[LOAD_AVG_PERIOD
];
2658 n
-= LOAD_AVG_PERIOD
;
2659 } while (n
> LOAD_AVG_PERIOD
);
2661 contrib
= decay_load(contrib
, n
);
2662 return contrib
+ runnable_avg_yN_sum
[n
];
2665 #if (SCHED_LOAD_SHIFT - SCHED_LOAD_RESOLUTION) != 10 || SCHED_CAPACITY_SHIFT != 10
2666 #error "load tracking assumes 2^10 as unit"
2669 #define cap_scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT)
2672 * We can represent the historical contribution to runnable average as the
2673 * coefficients of a geometric series. To do this we sub-divide our runnable
2674 * history into segments of approximately 1ms (1024us); label the segment that
2675 * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g.
2677 * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ...
2679 * (now) (~1ms ago) (~2ms ago)
2681 * Let u_i denote the fraction of p_i that the entity was runnable.
2683 * We then designate the fractions u_i as our co-efficients, yielding the
2684 * following representation of historical load:
2685 * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ...
2687 * We choose y based on the with of a reasonably scheduling period, fixing:
2690 * This means that the contribution to load ~32ms ago (u_32) will be weighted
2691 * approximately half as much as the contribution to load within the last ms
2694 * When a period "rolls over" and we have new u_0`, multiplying the previous
2695 * sum again by y is sufficient to update:
2696 * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... )
2697 * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
2699 static __always_inline
int
2700 __update_load_avg(u64 now
, int cpu
, struct sched_avg
*sa
,
2701 unsigned long weight
, int running
, struct cfs_rq
*cfs_rq
)
2703 u64 delta
, scaled_delta
, periods
;
2705 unsigned int delta_w
, scaled_delta_w
, decayed
= 0;
2706 unsigned long scale_freq
, scale_cpu
;
2708 delta
= now
- sa
->last_update_time
;
2710 * This should only happen when time goes backwards, which it
2711 * unfortunately does during sched clock init when we swap over to TSC.
2713 if ((s64
)delta
< 0) {
2714 sa
->last_update_time
= now
;
2719 * Use 1024ns as the unit of measurement since it's a reasonable
2720 * approximation of 1us and fast to compute.
2725 sa
->last_update_time
= now
;
2727 scale_freq
= arch_scale_freq_capacity(NULL
, cpu
);
2728 scale_cpu
= arch_scale_cpu_capacity(NULL
, cpu
);
2730 /* delta_w is the amount already accumulated against our next period */
2731 delta_w
= sa
->period_contrib
;
2732 if (delta
+ delta_w
>= 1024) {
2735 /* how much left for next period will start over, we don't know yet */
2736 sa
->period_contrib
= 0;
2739 * Now that we know we're crossing a period boundary, figure
2740 * out how much from delta we need to complete the current
2741 * period and accrue it.
2743 delta_w
= 1024 - delta_w
;
2744 scaled_delta_w
= cap_scale(delta_w
, scale_freq
);
2746 sa
->load_sum
+= weight
* scaled_delta_w
;
2748 cfs_rq
->runnable_load_sum
+=
2749 weight
* scaled_delta_w
;
2753 sa
->util_sum
+= scaled_delta_w
* scale_cpu
;
2757 /* Figure out how many additional periods this update spans */
2758 periods
= delta
/ 1024;
2761 sa
->load_sum
= decay_load(sa
->load_sum
, periods
+ 1);
2763 cfs_rq
->runnable_load_sum
=
2764 decay_load(cfs_rq
->runnable_load_sum
, periods
+ 1);
2766 sa
->util_sum
= decay_load((u64
)(sa
->util_sum
), periods
+ 1);
2768 /* Efficiently calculate \sum (1..n_period) 1024*y^i */
2769 contrib
= __compute_runnable_contrib(periods
);
2770 contrib
= cap_scale(contrib
, scale_freq
);
2772 sa
->load_sum
+= weight
* contrib
;
2774 cfs_rq
->runnable_load_sum
+= weight
* contrib
;
2777 sa
->util_sum
+= contrib
* scale_cpu
;
2780 /* Remainder of delta accrued against u_0` */
2781 scaled_delta
= cap_scale(delta
, scale_freq
);
2783 sa
->load_sum
+= weight
* scaled_delta
;
2785 cfs_rq
->runnable_load_sum
+= weight
* scaled_delta
;
2788 sa
->util_sum
+= scaled_delta
* scale_cpu
;
2790 sa
->period_contrib
+= delta
;
2793 sa
->load_avg
= div_u64(sa
->load_sum
, LOAD_AVG_MAX
);
2795 cfs_rq
->runnable_load_avg
=
2796 div_u64(cfs_rq
->runnable_load_sum
, LOAD_AVG_MAX
);
2798 sa
->util_avg
= sa
->util_sum
/ LOAD_AVG_MAX
;
2804 #ifdef CONFIG_FAIR_GROUP_SCHED
2806 * Updating tg's load_avg is necessary before update_cfs_share (which is done)
2807 * and effective_load (which is not done because it is too costly).
2809 static inline void update_tg_load_avg(struct cfs_rq
*cfs_rq
, int force
)
2811 long delta
= cfs_rq
->avg
.load_avg
- cfs_rq
->tg_load_avg_contrib
;
2814 * No need to update load_avg for root_task_group as it is not used.
2816 if (cfs_rq
->tg
== &root_task_group
)
2819 if (force
|| abs(delta
) > cfs_rq
->tg_load_avg_contrib
/ 64) {
2820 atomic_long_add(delta
, &cfs_rq
->tg
->load_avg
);
2821 cfs_rq
->tg_load_avg_contrib
= cfs_rq
->avg
.load_avg
;
2826 * Called within set_task_rq() right before setting a task's cpu. The
2827 * caller only guarantees p->pi_lock is held; no other assumptions,
2828 * including the state of rq->lock, should be made.
2830 void set_task_rq_fair(struct sched_entity
*se
,
2831 struct cfs_rq
*prev
, struct cfs_rq
*next
)
2833 if (!sched_feat(ATTACH_AGE_LOAD
))
2837 * We are supposed to update the task to "current" time, then its up to
2838 * date and ready to go to new CPU/cfs_rq. But we have difficulty in
2839 * getting what current time is, so simply throw away the out-of-date
2840 * time. This will result in the wakee task is less decayed, but giving
2841 * the wakee more load sounds not bad.
2843 if (se
->avg
.last_update_time
&& prev
) {
2844 u64 p_last_update_time
;
2845 u64 n_last_update_time
;
2847 #ifndef CONFIG_64BIT
2848 u64 p_last_update_time_copy
;
2849 u64 n_last_update_time_copy
;
2852 p_last_update_time_copy
= prev
->load_last_update_time_copy
;
2853 n_last_update_time_copy
= next
->load_last_update_time_copy
;
2857 p_last_update_time
= prev
->avg
.last_update_time
;
2858 n_last_update_time
= next
->avg
.last_update_time
;
2860 } while (p_last_update_time
!= p_last_update_time_copy
||
2861 n_last_update_time
!= n_last_update_time_copy
);
2863 p_last_update_time
= prev
->avg
.last_update_time
;
2864 n_last_update_time
= next
->avg
.last_update_time
;
2866 __update_load_avg(p_last_update_time
, cpu_of(rq_of(prev
)),
2867 &se
->avg
, 0, 0, NULL
);
2868 se
->avg
.last_update_time
= n_last_update_time
;
2871 #else /* CONFIG_FAIR_GROUP_SCHED */
2872 static inline void update_tg_load_avg(struct cfs_rq
*cfs_rq
, int force
) {}
2873 #endif /* CONFIG_FAIR_GROUP_SCHED */
2875 static inline u64
cfs_rq_clock_task(struct cfs_rq
*cfs_rq
);
2877 static inline void cfs_rq_util_change(struct cfs_rq
*cfs_rq
)
2879 struct rq
*rq
= rq_of(cfs_rq
);
2880 int cpu
= cpu_of(rq
);
2882 if (cpu
== smp_processor_id() && &rq
->cfs
== cfs_rq
) {
2883 unsigned long max
= rq
->cpu_capacity_orig
;
2886 * There are a few boundary cases this might miss but it should
2887 * get called often enough that that should (hopefully) not be
2888 * a real problem -- added to that it only calls on the local
2889 * CPU, so if we enqueue remotely we'll miss an update, but
2890 * the next tick/schedule should update.
2892 * It will not get called when we go idle, because the idle
2893 * thread is a different class (!fair), nor will the utilization
2894 * number include things like RT tasks.
2896 * As is, the util number is not freq-invariant (we'd have to
2897 * implement arch_scale_freq_capacity() for that).
2901 cpufreq_update_util(rq_clock(rq
),
2902 min(cfs_rq
->avg
.util_avg
, max
), max
);
2906 /* Group cfs_rq's load_avg is used for task_h_load and update_cfs_share */
2908 update_cfs_rq_load_avg(u64 now
, struct cfs_rq
*cfs_rq
, bool update_freq
)
2910 struct sched_avg
*sa
= &cfs_rq
->avg
;
2911 int decayed
, removed_load
= 0, removed_util
= 0;
2913 if (atomic_long_read(&cfs_rq
->removed_load_avg
)) {
2914 s64 r
= atomic_long_xchg(&cfs_rq
->removed_load_avg
, 0);
2915 sa
->load_avg
= max_t(long, sa
->load_avg
- r
, 0);
2916 sa
->load_sum
= max_t(s64
, sa
->load_sum
- r
* LOAD_AVG_MAX
, 0);
2920 if (atomic_long_read(&cfs_rq
->removed_util_avg
)) {
2921 long r
= atomic_long_xchg(&cfs_rq
->removed_util_avg
, 0);
2922 sa
->util_avg
= max_t(long, sa
->util_avg
- r
, 0);
2923 sa
->util_sum
= max_t(s32
, sa
->util_sum
- r
* LOAD_AVG_MAX
, 0);
2927 decayed
= __update_load_avg(now
, cpu_of(rq_of(cfs_rq
)), sa
,
2928 scale_load_down(cfs_rq
->load
.weight
), cfs_rq
->curr
!= NULL
, cfs_rq
);
2930 #ifndef CONFIG_64BIT
2932 cfs_rq
->load_last_update_time_copy
= sa
->last_update_time
;
2935 if (update_freq
&& (decayed
|| removed_util
))
2936 cfs_rq_util_change(cfs_rq
);
2938 return decayed
|| removed_load
;
2941 /* Update task and its cfs_rq load average */
2942 static inline void update_load_avg(struct sched_entity
*se
, int update_tg
)
2944 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
2945 u64 now
= cfs_rq_clock_task(cfs_rq
);
2946 struct rq
*rq
= rq_of(cfs_rq
);
2947 int cpu
= cpu_of(rq
);
2950 * Track task load average for carrying it to new CPU after migrated, and
2951 * track group sched_entity load average for task_h_load calc in migration
2953 __update_load_avg(now
, cpu
, &se
->avg
,
2954 se
->on_rq
* scale_load_down(se
->load
.weight
),
2955 cfs_rq
->curr
== se
, NULL
);
2957 if (update_cfs_rq_load_avg(now
, cfs_rq
, true) && update_tg
)
2958 update_tg_load_avg(cfs_rq
, 0);
2961 static void attach_entity_load_avg(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
2963 if (!sched_feat(ATTACH_AGE_LOAD
))
2967 * If we got migrated (either between CPUs or between cgroups) we'll
2968 * have aged the average right before clearing @last_update_time.
2970 if (se
->avg
.last_update_time
) {
2971 __update_load_avg(cfs_rq
->avg
.last_update_time
, cpu_of(rq_of(cfs_rq
)),
2972 &se
->avg
, 0, 0, NULL
);
2975 * XXX: we could have just aged the entire load away if we've been
2976 * absent from the fair class for too long.
2981 se
->avg
.last_update_time
= cfs_rq
->avg
.last_update_time
;
2982 cfs_rq
->avg
.load_avg
+= se
->avg
.load_avg
;
2983 cfs_rq
->avg
.load_sum
+= se
->avg
.load_sum
;
2984 cfs_rq
->avg
.util_avg
+= se
->avg
.util_avg
;
2985 cfs_rq
->avg
.util_sum
+= se
->avg
.util_sum
;
2987 cfs_rq_util_change(cfs_rq
);
2990 static void detach_entity_load_avg(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
2992 __update_load_avg(cfs_rq
->avg
.last_update_time
, cpu_of(rq_of(cfs_rq
)),
2993 &se
->avg
, se
->on_rq
* scale_load_down(se
->load
.weight
),
2994 cfs_rq
->curr
== se
, NULL
);
2996 cfs_rq
->avg
.load_avg
= max_t(long, cfs_rq
->avg
.load_avg
- se
->avg
.load_avg
, 0);
2997 cfs_rq
->avg
.load_sum
= max_t(s64
, cfs_rq
->avg
.load_sum
- se
->avg
.load_sum
, 0);
2998 cfs_rq
->avg
.util_avg
= max_t(long, cfs_rq
->avg
.util_avg
- se
->avg
.util_avg
, 0);
2999 cfs_rq
->avg
.util_sum
= max_t(s32
, cfs_rq
->avg
.util_sum
- se
->avg
.util_sum
, 0);
3001 cfs_rq_util_change(cfs_rq
);
3004 /* Add the load generated by se into cfs_rq's load average */
3006 enqueue_entity_load_avg(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
3008 struct sched_avg
*sa
= &se
->avg
;
3009 u64 now
= cfs_rq_clock_task(cfs_rq
);
3010 int migrated
, decayed
;
3012 migrated
= !sa
->last_update_time
;
3014 __update_load_avg(now
, cpu_of(rq_of(cfs_rq
)), sa
,
3015 se
->on_rq
* scale_load_down(se
->load
.weight
),
3016 cfs_rq
->curr
== se
, NULL
);
3019 decayed
= update_cfs_rq_load_avg(now
, cfs_rq
, !migrated
);
3021 cfs_rq
->runnable_load_avg
+= sa
->load_avg
;
3022 cfs_rq
->runnable_load_sum
+= sa
->load_sum
;
3025 attach_entity_load_avg(cfs_rq
, se
);
3027 if (decayed
|| migrated
)
3028 update_tg_load_avg(cfs_rq
, 0);
3031 /* Remove the runnable load generated by se from cfs_rq's runnable load average */
3033 dequeue_entity_load_avg(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
3035 update_load_avg(se
, 1);
3037 cfs_rq
->runnable_load_avg
=
3038 max_t(long, cfs_rq
->runnable_load_avg
- se
->avg
.load_avg
, 0);
3039 cfs_rq
->runnable_load_sum
=
3040 max_t(s64
, cfs_rq
->runnable_load_sum
- se
->avg
.load_sum
, 0);
3043 #ifndef CONFIG_64BIT
3044 static inline u64
cfs_rq_last_update_time(struct cfs_rq
*cfs_rq
)
3046 u64 last_update_time_copy
;
3047 u64 last_update_time
;
3050 last_update_time_copy
= cfs_rq
->load_last_update_time_copy
;
3052 last_update_time
= cfs_rq
->avg
.last_update_time
;
3053 } while (last_update_time
!= last_update_time_copy
);
3055 return last_update_time
;
3058 static inline u64
cfs_rq_last_update_time(struct cfs_rq
*cfs_rq
)
3060 return cfs_rq
->avg
.last_update_time
;
3065 * Task first catches up with cfs_rq, and then subtract
3066 * itself from the cfs_rq (task must be off the queue now).
3068 void remove_entity_load_avg(struct sched_entity
*se
)
3070 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
3071 u64 last_update_time
;
3074 * Newly created task or never used group entity should not be removed
3075 * from its (source) cfs_rq
3077 if (se
->avg
.last_update_time
== 0)
3080 last_update_time
= cfs_rq_last_update_time(cfs_rq
);
3082 __update_load_avg(last_update_time
, cpu_of(rq_of(cfs_rq
)), &se
->avg
, 0, 0, NULL
);
3083 atomic_long_add(se
->avg
.load_avg
, &cfs_rq
->removed_load_avg
);
3084 atomic_long_add(se
->avg
.util_avg
, &cfs_rq
->removed_util_avg
);
3087 static inline unsigned long cfs_rq_runnable_load_avg(struct cfs_rq
*cfs_rq
)
3089 return cfs_rq
->runnable_load_avg
;
3092 static inline unsigned long cfs_rq_load_avg(struct cfs_rq
*cfs_rq
)
3094 return cfs_rq
->avg
.load_avg
;
3097 static int idle_balance(struct rq
*this_rq
);
3099 #else /* CONFIG_SMP */
3101 static inline void update_load_avg(struct sched_entity
*se
, int update_tg
) {}
3103 enqueue_entity_load_avg(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
) {}
3105 dequeue_entity_load_avg(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
) {}
3106 static inline void remove_entity_load_avg(struct sched_entity
*se
) {}
3109 attach_entity_load_avg(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
) {}
3111 detach_entity_load_avg(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
) {}
3113 static inline int idle_balance(struct rq
*rq
)
3118 #endif /* CONFIG_SMP */
3120 static void enqueue_sleeper(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
3122 #ifdef CONFIG_SCHEDSTATS
3123 struct task_struct
*tsk
= NULL
;
3125 if (entity_is_task(se
))
3128 if (se
->statistics
.sleep_start
) {
3129 u64 delta
= rq_clock(rq_of(cfs_rq
)) - se
->statistics
.sleep_start
;
3134 if (unlikely(delta
> se
->statistics
.sleep_max
))
3135 se
->statistics
.sleep_max
= delta
;
3137 se
->statistics
.sleep_start
= 0;
3138 se
->statistics
.sum_sleep_runtime
+= delta
;
3141 account_scheduler_latency(tsk
, delta
>> 10, 1);
3142 trace_sched_stat_sleep(tsk
, delta
);
3145 if (se
->statistics
.block_start
) {
3146 u64 delta
= rq_clock(rq_of(cfs_rq
)) - se
->statistics
.block_start
;
3151 if (unlikely(delta
> se
->statistics
.block_max
))
3152 se
->statistics
.block_max
= delta
;
3154 se
->statistics
.block_start
= 0;
3155 se
->statistics
.sum_sleep_runtime
+= delta
;
3158 if (tsk
->in_iowait
) {
3159 se
->statistics
.iowait_sum
+= delta
;
3160 se
->statistics
.iowait_count
++;
3161 trace_sched_stat_iowait(tsk
, delta
);
3164 trace_sched_stat_blocked(tsk
, delta
);
3167 * Blocking time is in units of nanosecs, so shift by
3168 * 20 to get a milliseconds-range estimation of the
3169 * amount of time that the task spent sleeping:
3171 if (unlikely(prof_on
== SLEEP_PROFILING
)) {
3172 profile_hits(SLEEP_PROFILING
,
3173 (void *)get_wchan(tsk
),
3176 account_scheduler_latency(tsk
, delta
>> 10, 0);
3182 static void check_spread(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
3184 #ifdef CONFIG_SCHED_DEBUG
3185 s64 d
= se
->vruntime
- cfs_rq
->min_vruntime
;
3190 if (d
> 3*sysctl_sched_latency
)
3191 schedstat_inc(cfs_rq
, nr_spread_over
);
3196 place_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int initial
)
3198 u64 vruntime
= cfs_rq
->min_vruntime
;
3201 * The 'current' period is already promised to the current tasks,
3202 * however the extra weight of the new task will slow them down a
3203 * little, place the new task so that it fits in the slot that
3204 * stays open at the end.
3206 if (initial
&& sched_feat(START_DEBIT
))
3207 vruntime
+= sched_vslice(cfs_rq
, se
);
3209 /* sleeps up to a single latency don't count. */
3211 unsigned long thresh
= sysctl_sched_latency
;
3214 * Halve their sleep time's effect, to allow
3215 * for a gentler effect of sleepers:
3217 if (sched_feat(GENTLE_FAIR_SLEEPERS
))
3223 /* ensure we never gain time by being placed backwards. */
3224 se
->vruntime
= max_vruntime(se
->vruntime
, vruntime
);
3227 static void check_enqueue_throttle(struct cfs_rq
*cfs_rq
);
3229 static inline void check_schedstat_required(void)
3231 #ifdef CONFIG_SCHEDSTATS
3232 if (schedstat_enabled())
3235 /* Force schedstat enabled if a dependent tracepoint is active */
3236 if (trace_sched_stat_wait_enabled() ||
3237 trace_sched_stat_sleep_enabled() ||
3238 trace_sched_stat_iowait_enabled() ||
3239 trace_sched_stat_blocked_enabled() ||
3240 trace_sched_stat_runtime_enabled()) {
3241 pr_warn_once("Scheduler tracepoints stat_sleep, stat_iowait, "
3242 "stat_blocked and stat_runtime require the "
3243 "kernel parameter schedstats=enabled or "
3244 "kernel.sched_schedstats=1\n");
3250 enqueue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int flags
)
3252 bool renorm
= !(flags
& ENQUEUE_WAKEUP
) || (flags
& ENQUEUE_WAKING
);
3253 bool curr
= cfs_rq
->curr
== se
;
3256 * If we're the current task, we must renormalise before calling
3260 se
->vruntime
+= cfs_rq
->min_vruntime
;
3262 update_curr(cfs_rq
);
3265 * Otherwise, renormalise after, such that we're placed at the current
3266 * moment in time, instead of some random moment in the past.
3268 if (renorm
&& !curr
)
3269 se
->vruntime
+= cfs_rq
->min_vruntime
;
3271 enqueue_entity_load_avg(cfs_rq
, se
);
3272 account_entity_enqueue(cfs_rq
, se
);
3273 update_cfs_shares(cfs_rq
);
3275 if (flags
& ENQUEUE_WAKEUP
) {
3276 place_entity(cfs_rq
, se
, 0);
3277 if (schedstat_enabled())
3278 enqueue_sleeper(cfs_rq
, se
);
3281 check_schedstat_required();
3282 if (schedstat_enabled()) {
3283 update_stats_enqueue(cfs_rq
, se
);
3284 check_spread(cfs_rq
, se
);
3287 __enqueue_entity(cfs_rq
, se
);
3290 if (cfs_rq
->nr_running
== 1) {
3291 list_add_leaf_cfs_rq(cfs_rq
);
3292 check_enqueue_throttle(cfs_rq
);
3296 static void __clear_buddies_last(struct sched_entity
*se
)
3298 for_each_sched_entity(se
) {
3299 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
3300 if (cfs_rq
->last
!= se
)
3303 cfs_rq
->last
= NULL
;
3307 static void __clear_buddies_next(struct sched_entity
*se
)
3309 for_each_sched_entity(se
) {
3310 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
3311 if (cfs_rq
->next
!= se
)
3314 cfs_rq
->next
= NULL
;
3318 static void __clear_buddies_skip(struct sched_entity
*se
)
3320 for_each_sched_entity(se
) {
3321 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
3322 if (cfs_rq
->skip
!= se
)
3325 cfs_rq
->skip
= NULL
;
3329 static void clear_buddies(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
3331 if (cfs_rq
->last
== se
)
3332 __clear_buddies_last(se
);
3334 if (cfs_rq
->next
== se
)
3335 __clear_buddies_next(se
);
3337 if (cfs_rq
->skip
== se
)
3338 __clear_buddies_skip(se
);
3341 static __always_inline
void return_cfs_rq_runtime(struct cfs_rq
*cfs_rq
);
3344 dequeue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int flags
)
3347 * Update run-time statistics of the 'current'.
3349 update_curr(cfs_rq
);
3350 dequeue_entity_load_avg(cfs_rq
, se
);
3352 if (schedstat_enabled())
3353 update_stats_dequeue(cfs_rq
, se
, flags
);
3355 clear_buddies(cfs_rq
, se
);
3357 if (se
!= cfs_rq
->curr
)
3358 __dequeue_entity(cfs_rq
, se
);
3360 account_entity_dequeue(cfs_rq
, se
);
3363 * Normalize the entity after updating the min_vruntime because the
3364 * update can refer to the ->curr item and we need to reflect this
3365 * movement in our normalized position.
3367 if (!(flags
& DEQUEUE_SLEEP
))
3368 se
->vruntime
-= cfs_rq
->min_vruntime
;
3370 /* return excess runtime on last dequeue */
3371 return_cfs_rq_runtime(cfs_rq
);
3373 update_min_vruntime(cfs_rq
);
3374 update_cfs_shares(cfs_rq
);
3378 * Preempt the current task with a newly woken task if needed:
3381 check_preempt_tick(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
)
3383 unsigned long ideal_runtime
, delta_exec
;
3384 struct sched_entity
*se
;
3387 ideal_runtime
= sched_slice(cfs_rq
, curr
);
3388 delta_exec
= curr
->sum_exec_runtime
- curr
->prev_sum_exec_runtime
;
3389 if (delta_exec
> ideal_runtime
) {
3390 resched_curr(rq_of(cfs_rq
));
3392 * The current task ran long enough, ensure it doesn't get
3393 * re-elected due to buddy favours.
3395 clear_buddies(cfs_rq
, curr
);
3400 * Ensure that a task that missed wakeup preemption by a
3401 * narrow margin doesn't have to wait for a full slice.
3402 * This also mitigates buddy induced latencies under load.
3404 if (delta_exec
< sysctl_sched_min_granularity
)
3407 se
= __pick_first_entity(cfs_rq
);
3408 delta
= curr
->vruntime
- se
->vruntime
;
3413 if (delta
> ideal_runtime
)
3414 resched_curr(rq_of(cfs_rq
));
3418 set_next_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
3420 /* 'current' is not kept within the tree. */
3423 * Any task has to be enqueued before it get to execute on
3424 * a CPU. So account for the time it spent waiting on the
3427 if (schedstat_enabled())
3428 update_stats_wait_end(cfs_rq
, se
);
3429 __dequeue_entity(cfs_rq
, se
);
3430 update_load_avg(se
, 1);
3433 update_stats_curr_start(cfs_rq
, se
);
3435 #ifdef CONFIG_SCHEDSTATS
3437 * Track our maximum slice length, if the CPU's load is at
3438 * least twice that of our own weight (i.e. dont track it
3439 * when there are only lesser-weight tasks around):
3441 if (schedstat_enabled() && rq_of(cfs_rq
)->load
.weight
>= 2*se
->load
.weight
) {
3442 se
->statistics
.slice_max
= max(se
->statistics
.slice_max
,
3443 se
->sum_exec_runtime
- se
->prev_sum_exec_runtime
);
3446 se
->prev_sum_exec_runtime
= se
->sum_exec_runtime
;
3450 wakeup_preempt_entity(struct sched_entity
*curr
, struct sched_entity
*se
);
3453 * Pick the next process, keeping these things in mind, in this order:
3454 * 1) keep things fair between processes/task groups
3455 * 2) pick the "next" process, since someone really wants that to run
3456 * 3) pick the "last" process, for cache locality
3457 * 4) do not run the "skip" process, if something else is available
3459 static struct sched_entity
*
3460 pick_next_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
)
3462 struct sched_entity
*left
= __pick_first_entity(cfs_rq
);
3463 struct sched_entity
*se
;
3466 * If curr is set we have to see if its left of the leftmost entity
3467 * still in the tree, provided there was anything in the tree at all.
3469 if (!left
|| (curr
&& entity_before(curr
, left
)))
3472 se
= left
; /* ideally we run the leftmost entity */
3475 * Avoid running the skip buddy, if running something else can
3476 * be done without getting too unfair.
3478 if (cfs_rq
->skip
== se
) {
3479 struct sched_entity
*second
;
3482 second
= __pick_first_entity(cfs_rq
);
3484 second
= __pick_next_entity(se
);
3485 if (!second
|| (curr
&& entity_before(curr
, second
)))
3489 if (second
&& wakeup_preempt_entity(second
, left
) < 1)
3494 * Prefer last buddy, try to return the CPU to a preempted task.
3496 if (cfs_rq
->last
&& wakeup_preempt_entity(cfs_rq
->last
, left
) < 1)
3500 * Someone really wants this to run. If it's not unfair, run it.
3502 if (cfs_rq
->next
&& wakeup_preempt_entity(cfs_rq
->next
, left
) < 1)
3505 clear_buddies(cfs_rq
, se
);
3510 static bool check_cfs_rq_runtime(struct cfs_rq
*cfs_rq
);
3512 static void put_prev_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*prev
)
3515 * If still on the runqueue then deactivate_task()
3516 * was not called and update_curr() has to be done:
3519 update_curr(cfs_rq
);
3521 /* throttle cfs_rqs exceeding runtime */
3522 check_cfs_rq_runtime(cfs_rq
);
3524 if (schedstat_enabled()) {
3525 check_spread(cfs_rq
, prev
);
3527 update_stats_wait_start(cfs_rq
, prev
);
3531 /* Put 'current' back into the tree. */
3532 __enqueue_entity(cfs_rq
, prev
);
3533 /* in !on_rq case, update occurred at dequeue */
3534 update_load_avg(prev
, 0);
3536 cfs_rq
->curr
= NULL
;
3540 entity_tick(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
, int queued
)
3543 * Update run-time statistics of the 'current'.
3545 update_curr(cfs_rq
);
3548 * Ensure that runnable average is periodically updated.
3550 update_load_avg(curr
, 1);
3551 update_cfs_shares(cfs_rq
);
3553 #ifdef CONFIG_SCHED_HRTICK
3555 * queued ticks are scheduled to match the slice, so don't bother
3556 * validating it and just reschedule.
3559 resched_curr(rq_of(cfs_rq
));
3563 * don't let the period tick interfere with the hrtick preemption
3565 if (!sched_feat(DOUBLE_TICK
) &&
3566 hrtimer_active(&rq_of(cfs_rq
)->hrtick_timer
))
3570 if (cfs_rq
->nr_running
> 1)
3571 check_preempt_tick(cfs_rq
, curr
);
3575 /**************************************************
3576 * CFS bandwidth control machinery
3579 #ifdef CONFIG_CFS_BANDWIDTH
3581 #ifdef HAVE_JUMP_LABEL
3582 static struct static_key __cfs_bandwidth_used
;
3584 static inline bool cfs_bandwidth_used(void)
3586 return static_key_false(&__cfs_bandwidth_used
);
3589 void cfs_bandwidth_usage_inc(void)
3591 static_key_slow_inc(&__cfs_bandwidth_used
);
3594 void cfs_bandwidth_usage_dec(void)
3596 static_key_slow_dec(&__cfs_bandwidth_used
);
3598 #else /* HAVE_JUMP_LABEL */
3599 static bool cfs_bandwidth_used(void)
3604 void cfs_bandwidth_usage_inc(void) {}
3605 void cfs_bandwidth_usage_dec(void) {}
3606 #endif /* HAVE_JUMP_LABEL */
3609 * default period for cfs group bandwidth.
3610 * default: 0.1s, units: nanoseconds
3612 static inline u64
default_cfs_period(void)
3614 return 100000000ULL;
3617 static inline u64
sched_cfs_bandwidth_slice(void)
3619 return (u64
)sysctl_sched_cfs_bandwidth_slice
* NSEC_PER_USEC
;
3623 * Replenish runtime according to assigned quota and update expiration time.
3624 * We use sched_clock_cpu directly instead of rq->clock to avoid adding
3625 * additional synchronization around rq->lock.
3627 * requires cfs_b->lock
3629 void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth
*cfs_b
)
3633 if (cfs_b
->quota
== RUNTIME_INF
)
3636 now
= sched_clock_cpu(smp_processor_id());
3637 cfs_b
->runtime
= cfs_b
->quota
;
3638 cfs_b
->runtime_expires
= now
+ ktime_to_ns(cfs_b
->period
);
3641 static inline struct cfs_bandwidth
*tg_cfs_bandwidth(struct task_group
*tg
)
3643 return &tg
->cfs_bandwidth
;
3646 /* rq->task_clock normalized against any time this cfs_rq has spent throttled */
3647 static inline u64
cfs_rq_clock_task(struct cfs_rq
*cfs_rq
)
3649 if (unlikely(cfs_rq
->throttle_count
))
3650 return cfs_rq
->throttled_clock_task
;
3652 return rq_clock_task(rq_of(cfs_rq
)) - cfs_rq
->throttled_clock_task_time
;
3655 /* returns 0 on failure to allocate runtime */
3656 static int assign_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
3658 struct task_group
*tg
= cfs_rq
->tg
;
3659 struct cfs_bandwidth
*cfs_b
= tg_cfs_bandwidth(tg
);
3660 u64 amount
= 0, min_amount
, expires
;
3662 /* note: this is a positive sum as runtime_remaining <= 0 */
3663 min_amount
= sched_cfs_bandwidth_slice() - cfs_rq
->runtime_remaining
;
3665 raw_spin_lock(&cfs_b
->lock
);
3666 if (cfs_b
->quota
== RUNTIME_INF
)
3667 amount
= min_amount
;
3669 start_cfs_bandwidth(cfs_b
);
3671 if (cfs_b
->runtime
> 0) {
3672 amount
= min(cfs_b
->runtime
, min_amount
);
3673 cfs_b
->runtime
-= amount
;
3677 expires
= cfs_b
->runtime_expires
;
3678 raw_spin_unlock(&cfs_b
->lock
);
3680 cfs_rq
->runtime_remaining
+= amount
;
3682 * we may have advanced our local expiration to account for allowed
3683 * spread between our sched_clock and the one on which runtime was
3686 if ((s64
)(expires
- cfs_rq
->runtime_expires
) > 0)
3687 cfs_rq
->runtime_expires
= expires
;
3689 return cfs_rq
->runtime_remaining
> 0;
3693 * Note: This depends on the synchronization provided by sched_clock and the
3694 * fact that rq->clock snapshots this value.
3696 static void expire_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
3698 struct cfs_bandwidth
*cfs_b
= tg_cfs_bandwidth(cfs_rq
->tg
);
3700 /* if the deadline is ahead of our clock, nothing to do */
3701 if (likely((s64
)(rq_clock(rq_of(cfs_rq
)) - cfs_rq
->runtime_expires
) < 0))
3704 if (cfs_rq
->runtime_remaining
< 0)
3708 * If the local deadline has passed we have to consider the
3709 * possibility that our sched_clock is 'fast' and the global deadline
3710 * has not truly expired.
3712 * Fortunately we can check determine whether this the case by checking
3713 * whether the global deadline has advanced. It is valid to compare
3714 * cfs_b->runtime_expires without any locks since we only care about
3715 * exact equality, so a partial write will still work.
3718 if (cfs_rq
->runtime_expires
!= cfs_b
->runtime_expires
) {
3719 /* extend local deadline, drift is bounded above by 2 ticks */
3720 cfs_rq
->runtime_expires
+= TICK_NSEC
;
3722 /* global deadline is ahead, expiration has passed */
3723 cfs_rq
->runtime_remaining
= 0;
3727 static void __account_cfs_rq_runtime(struct cfs_rq
*cfs_rq
, u64 delta_exec
)
3729 /* dock delta_exec before expiring quota (as it could span periods) */
3730 cfs_rq
->runtime_remaining
-= delta_exec
;
3731 expire_cfs_rq_runtime(cfs_rq
);
3733 if (likely(cfs_rq
->runtime_remaining
> 0))
3737 * if we're unable to extend our runtime we resched so that the active
3738 * hierarchy can be throttled
3740 if (!assign_cfs_rq_runtime(cfs_rq
) && likely(cfs_rq
->curr
))
3741 resched_curr(rq_of(cfs_rq
));
3744 static __always_inline
3745 void account_cfs_rq_runtime(struct cfs_rq
*cfs_rq
, u64 delta_exec
)
3747 if (!cfs_bandwidth_used() || !cfs_rq
->runtime_enabled
)
3750 __account_cfs_rq_runtime(cfs_rq
, delta_exec
);
3753 static inline int cfs_rq_throttled(struct cfs_rq
*cfs_rq
)
3755 return cfs_bandwidth_used() && cfs_rq
->throttled
;
3758 /* check whether cfs_rq, or any parent, is throttled */
3759 static inline int throttled_hierarchy(struct cfs_rq
*cfs_rq
)
3761 return cfs_bandwidth_used() && cfs_rq
->throttle_count
;
3765 * Ensure that neither of the group entities corresponding to src_cpu or
3766 * dest_cpu are members of a throttled hierarchy when performing group
3767 * load-balance operations.
3769 static inline int throttled_lb_pair(struct task_group
*tg
,
3770 int src_cpu
, int dest_cpu
)
3772 struct cfs_rq
*src_cfs_rq
, *dest_cfs_rq
;
3774 src_cfs_rq
= tg
->cfs_rq
[src_cpu
];
3775 dest_cfs_rq
= tg
->cfs_rq
[dest_cpu
];
3777 return throttled_hierarchy(src_cfs_rq
) ||
3778 throttled_hierarchy(dest_cfs_rq
);
3781 /* updated child weight may affect parent so we have to do this bottom up */
3782 static int tg_unthrottle_up(struct task_group
*tg
, void *data
)
3784 struct rq
*rq
= data
;
3785 struct cfs_rq
*cfs_rq
= tg
->cfs_rq
[cpu_of(rq
)];
3787 cfs_rq
->throttle_count
--;
3789 if (!cfs_rq
->throttle_count
) {
3790 /* adjust cfs_rq_clock_task() */
3791 cfs_rq
->throttled_clock_task_time
+= rq_clock_task(rq
) -
3792 cfs_rq
->throttled_clock_task
;
3799 static int tg_throttle_down(struct task_group
*tg
, void *data
)
3801 struct rq
*rq
= data
;
3802 struct cfs_rq
*cfs_rq
= tg
->cfs_rq
[cpu_of(rq
)];
3804 /* group is entering throttled state, stop time */
3805 if (!cfs_rq
->throttle_count
)
3806 cfs_rq
->throttled_clock_task
= rq_clock_task(rq
);
3807 cfs_rq
->throttle_count
++;
3812 static void throttle_cfs_rq(struct cfs_rq
*cfs_rq
)
3814 struct rq
*rq
= rq_of(cfs_rq
);
3815 struct cfs_bandwidth
*cfs_b
= tg_cfs_bandwidth(cfs_rq
->tg
);
3816 struct sched_entity
*se
;
3817 long task_delta
, dequeue
= 1;
3820 se
= cfs_rq
->tg
->se
[cpu_of(rq_of(cfs_rq
))];
3822 /* freeze hierarchy runnable averages while throttled */
3824 walk_tg_tree_from(cfs_rq
->tg
, tg_throttle_down
, tg_nop
, (void *)rq
);
3827 task_delta
= cfs_rq
->h_nr_running
;
3828 for_each_sched_entity(se
) {
3829 struct cfs_rq
*qcfs_rq
= cfs_rq_of(se
);
3830 /* throttled entity or throttle-on-deactivate */
3835 dequeue_entity(qcfs_rq
, se
, DEQUEUE_SLEEP
);
3836 qcfs_rq
->h_nr_running
-= task_delta
;
3838 if (qcfs_rq
->load
.weight
)
3843 sub_nr_running(rq
, task_delta
);
3845 cfs_rq
->throttled
= 1;
3846 cfs_rq
->throttled_clock
= rq_clock(rq
);
3847 raw_spin_lock(&cfs_b
->lock
);
3848 empty
= list_empty(&cfs_b
->throttled_cfs_rq
);
3851 * Add to the _head_ of the list, so that an already-started
3852 * distribute_cfs_runtime will not see us
3854 list_add_rcu(&cfs_rq
->throttled_list
, &cfs_b
->throttled_cfs_rq
);
3857 * If we're the first throttled task, make sure the bandwidth
3861 start_cfs_bandwidth(cfs_b
);
3863 raw_spin_unlock(&cfs_b
->lock
);
3866 void unthrottle_cfs_rq(struct cfs_rq
*cfs_rq
)
3868 struct rq
*rq
= rq_of(cfs_rq
);
3869 struct cfs_bandwidth
*cfs_b
= tg_cfs_bandwidth(cfs_rq
->tg
);
3870 struct sched_entity
*se
;
3874 se
= cfs_rq
->tg
->se
[cpu_of(rq
)];
3876 cfs_rq
->throttled
= 0;
3878 update_rq_clock(rq
);
3880 raw_spin_lock(&cfs_b
->lock
);
3881 cfs_b
->throttled_time
+= rq_clock(rq
) - cfs_rq
->throttled_clock
;
3882 list_del_rcu(&cfs_rq
->throttled_list
);
3883 raw_spin_unlock(&cfs_b
->lock
);
3885 /* update hierarchical throttle state */
3886 walk_tg_tree_from(cfs_rq
->tg
, tg_nop
, tg_unthrottle_up
, (void *)rq
);
3888 if (!cfs_rq
->load
.weight
)
3891 task_delta
= cfs_rq
->h_nr_running
;
3892 for_each_sched_entity(se
) {
3896 cfs_rq
= cfs_rq_of(se
);
3898 enqueue_entity(cfs_rq
, se
, ENQUEUE_WAKEUP
);
3899 cfs_rq
->h_nr_running
+= task_delta
;
3901 if (cfs_rq_throttled(cfs_rq
))
3906 add_nr_running(rq
, task_delta
);
3908 /* determine whether we need to wake up potentially idle cpu */
3909 if (rq
->curr
== rq
->idle
&& rq
->cfs
.nr_running
)
3913 static u64
distribute_cfs_runtime(struct cfs_bandwidth
*cfs_b
,
3914 u64 remaining
, u64 expires
)
3916 struct cfs_rq
*cfs_rq
;
3918 u64 starting_runtime
= remaining
;
3921 list_for_each_entry_rcu(cfs_rq
, &cfs_b
->throttled_cfs_rq
,
3923 struct rq
*rq
= rq_of(cfs_rq
);
3925 raw_spin_lock(&rq
->lock
);
3926 if (!cfs_rq_throttled(cfs_rq
))
3929 runtime
= -cfs_rq
->runtime_remaining
+ 1;
3930 if (runtime
> remaining
)
3931 runtime
= remaining
;
3932 remaining
-= runtime
;
3934 cfs_rq
->runtime_remaining
+= runtime
;
3935 cfs_rq
->runtime_expires
= expires
;
3937 /* we check whether we're throttled above */
3938 if (cfs_rq
->runtime_remaining
> 0)
3939 unthrottle_cfs_rq(cfs_rq
);
3942 raw_spin_unlock(&rq
->lock
);
3949 return starting_runtime
- remaining
;
3953 * Responsible for refilling a task_group's bandwidth and unthrottling its
3954 * cfs_rqs as appropriate. If there has been no activity within the last
3955 * period the timer is deactivated until scheduling resumes; cfs_b->idle is
3956 * used to track this state.
3958 static int do_sched_cfs_period_timer(struct cfs_bandwidth
*cfs_b
, int overrun
)
3960 u64 runtime
, runtime_expires
;
3963 /* no need to continue the timer with no bandwidth constraint */
3964 if (cfs_b
->quota
== RUNTIME_INF
)
3965 goto out_deactivate
;
3967 throttled
= !list_empty(&cfs_b
->throttled_cfs_rq
);
3968 cfs_b
->nr_periods
+= overrun
;
3971 * idle depends on !throttled (for the case of a large deficit), and if
3972 * we're going inactive then everything else can be deferred
3974 if (cfs_b
->idle
&& !throttled
)
3975 goto out_deactivate
;
3977 __refill_cfs_bandwidth_runtime(cfs_b
);
3980 /* mark as potentially idle for the upcoming period */
3985 /* account preceding periods in which throttling occurred */
3986 cfs_b
->nr_throttled
+= overrun
;
3988 runtime_expires
= cfs_b
->runtime_expires
;
3991 * This check is repeated as we are holding onto the new bandwidth while
3992 * we unthrottle. This can potentially race with an unthrottled group
3993 * trying to acquire new bandwidth from the global pool. This can result
3994 * in us over-using our runtime if it is all used during this loop, but
3995 * only by limited amounts in that extreme case.
3997 while (throttled
&& cfs_b
->runtime
> 0) {
3998 runtime
= cfs_b
->runtime
;
3999 raw_spin_unlock(&cfs_b
->lock
);
4000 /* we can't nest cfs_b->lock while distributing bandwidth */
4001 runtime
= distribute_cfs_runtime(cfs_b
, runtime
,
4003 raw_spin_lock(&cfs_b
->lock
);
4005 throttled
= !list_empty(&cfs_b
->throttled_cfs_rq
);
4007 cfs_b
->runtime
-= min(runtime
, cfs_b
->runtime
);
4011 * While we are ensured activity in the period following an
4012 * unthrottle, this also covers the case in which the new bandwidth is
4013 * insufficient to cover the existing bandwidth deficit. (Forcing the
4014 * timer to remain active while there are any throttled entities.)
4024 /* a cfs_rq won't donate quota below this amount */
4025 static const u64 min_cfs_rq_runtime
= 1 * NSEC_PER_MSEC
;
4026 /* minimum remaining period time to redistribute slack quota */
4027 static const u64 min_bandwidth_expiration
= 2 * NSEC_PER_MSEC
;
4028 /* how long we wait to gather additional slack before distributing */
4029 static const u64 cfs_bandwidth_slack_period
= 5 * NSEC_PER_MSEC
;
4032 * Are we near the end of the current quota period?
4034 * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the
4035 * hrtimer base being cleared by hrtimer_start. In the case of
4036 * migrate_hrtimers, base is never cleared, so we are fine.
4038 static int runtime_refresh_within(struct cfs_bandwidth
*cfs_b
, u64 min_expire
)
4040 struct hrtimer
*refresh_timer
= &cfs_b
->period_timer
;
4043 /* if the call-back is running a quota refresh is already occurring */
4044 if (hrtimer_callback_running(refresh_timer
))
4047 /* is a quota refresh about to occur? */
4048 remaining
= ktime_to_ns(hrtimer_expires_remaining(refresh_timer
));
4049 if (remaining
< min_expire
)
4055 static void start_cfs_slack_bandwidth(struct cfs_bandwidth
*cfs_b
)
4057 u64 min_left
= cfs_bandwidth_slack_period
+ min_bandwidth_expiration
;
4059 /* if there's a quota refresh soon don't bother with slack */
4060 if (runtime_refresh_within(cfs_b
, min_left
))
4063 hrtimer_start(&cfs_b
->slack_timer
,
4064 ns_to_ktime(cfs_bandwidth_slack_period
),
4068 /* we know any runtime found here is valid as update_curr() precedes return */
4069 static void __return_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
4071 struct cfs_bandwidth
*cfs_b
= tg_cfs_bandwidth(cfs_rq
->tg
);
4072 s64 slack_runtime
= cfs_rq
->runtime_remaining
- min_cfs_rq_runtime
;
4074 if (slack_runtime
<= 0)
4077 raw_spin_lock(&cfs_b
->lock
);
4078 if (cfs_b
->quota
!= RUNTIME_INF
&&
4079 cfs_rq
->runtime_expires
== cfs_b
->runtime_expires
) {
4080 cfs_b
->runtime
+= slack_runtime
;
4082 /* we are under rq->lock, defer unthrottling using a timer */
4083 if (cfs_b
->runtime
> sched_cfs_bandwidth_slice() &&
4084 !list_empty(&cfs_b
->throttled_cfs_rq
))
4085 start_cfs_slack_bandwidth(cfs_b
);
4087 raw_spin_unlock(&cfs_b
->lock
);
4089 /* even if it's not valid for return we don't want to try again */
4090 cfs_rq
->runtime_remaining
-= slack_runtime
;
4093 static __always_inline
void return_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
4095 if (!cfs_bandwidth_used())
4098 if (!cfs_rq
->runtime_enabled
|| cfs_rq
->nr_running
)
4101 __return_cfs_rq_runtime(cfs_rq
);
4105 * This is done with a timer (instead of inline with bandwidth return) since
4106 * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
4108 static void do_sched_cfs_slack_timer(struct cfs_bandwidth
*cfs_b
)
4110 u64 runtime
= 0, slice
= sched_cfs_bandwidth_slice();
4113 /* confirm we're still not at a refresh boundary */
4114 raw_spin_lock(&cfs_b
->lock
);
4115 if (runtime_refresh_within(cfs_b
, min_bandwidth_expiration
)) {
4116 raw_spin_unlock(&cfs_b
->lock
);
4120 if (cfs_b
->quota
!= RUNTIME_INF
&& cfs_b
->runtime
> slice
)
4121 runtime
= cfs_b
->runtime
;
4123 expires
= cfs_b
->runtime_expires
;
4124 raw_spin_unlock(&cfs_b
->lock
);
4129 runtime
= distribute_cfs_runtime(cfs_b
, runtime
, expires
);
4131 raw_spin_lock(&cfs_b
->lock
);
4132 if (expires
== cfs_b
->runtime_expires
)
4133 cfs_b
->runtime
-= min(runtime
, cfs_b
->runtime
);
4134 raw_spin_unlock(&cfs_b
->lock
);
4138 * When a group wakes up we want to make sure that its quota is not already
4139 * expired/exceeded, otherwise it may be allowed to steal additional ticks of
4140 * runtime as update_curr() throttling can not not trigger until it's on-rq.
4142 static void check_enqueue_throttle(struct cfs_rq
*cfs_rq
)
4144 if (!cfs_bandwidth_used())
4147 /* an active group must be handled by the update_curr()->put() path */
4148 if (!cfs_rq
->runtime_enabled
|| cfs_rq
->curr
)
4151 /* ensure the group is not already throttled */
4152 if (cfs_rq_throttled(cfs_rq
))
4155 /* update runtime allocation */
4156 account_cfs_rq_runtime(cfs_rq
, 0);
4157 if (cfs_rq
->runtime_remaining
<= 0)
4158 throttle_cfs_rq(cfs_rq
);
4161 /* conditionally throttle active cfs_rq's from put_prev_entity() */
4162 static bool check_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
4164 if (!cfs_bandwidth_used())
4167 if (likely(!cfs_rq
->runtime_enabled
|| cfs_rq
->runtime_remaining
> 0))
4171 * it's possible for a throttled entity to be forced into a running
4172 * state (e.g. set_curr_task), in this case we're finished.
4174 if (cfs_rq_throttled(cfs_rq
))
4177 throttle_cfs_rq(cfs_rq
);
4181 static enum hrtimer_restart
sched_cfs_slack_timer(struct hrtimer
*timer
)
4183 struct cfs_bandwidth
*cfs_b
=
4184 container_of(timer
, struct cfs_bandwidth
, slack_timer
);
4186 do_sched_cfs_slack_timer(cfs_b
);
4188 return HRTIMER_NORESTART
;
4191 static enum hrtimer_restart
sched_cfs_period_timer(struct hrtimer
*timer
)
4193 struct cfs_bandwidth
*cfs_b
=
4194 container_of(timer
, struct cfs_bandwidth
, period_timer
);
4198 raw_spin_lock(&cfs_b
->lock
);
4200 overrun
= hrtimer_forward_now(timer
, cfs_b
->period
);
4204 idle
= do_sched_cfs_period_timer(cfs_b
, overrun
);
4207 cfs_b
->period_active
= 0;
4208 raw_spin_unlock(&cfs_b
->lock
);
4210 return idle
? HRTIMER_NORESTART
: HRTIMER_RESTART
;
4213 void init_cfs_bandwidth(struct cfs_bandwidth
*cfs_b
)
4215 raw_spin_lock_init(&cfs_b
->lock
);
4217 cfs_b
->quota
= RUNTIME_INF
;
4218 cfs_b
->period
= ns_to_ktime(default_cfs_period());
4220 INIT_LIST_HEAD(&cfs_b
->throttled_cfs_rq
);
4221 hrtimer_init(&cfs_b
->period_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_ABS_PINNED
);
4222 cfs_b
->period_timer
.function
= sched_cfs_period_timer
;
4223 hrtimer_init(&cfs_b
->slack_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
4224 cfs_b
->slack_timer
.function
= sched_cfs_slack_timer
;
4227 static void init_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
4229 cfs_rq
->runtime_enabled
= 0;
4230 INIT_LIST_HEAD(&cfs_rq
->throttled_list
);
4233 void start_cfs_bandwidth(struct cfs_bandwidth
*cfs_b
)
4235 lockdep_assert_held(&cfs_b
->lock
);
4237 if (!cfs_b
->period_active
) {
4238 cfs_b
->period_active
= 1;
4239 hrtimer_forward_now(&cfs_b
->period_timer
, cfs_b
->period
);
4240 hrtimer_start_expires(&cfs_b
->period_timer
, HRTIMER_MODE_ABS_PINNED
);
4244 static void destroy_cfs_bandwidth(struct cfs_bandwidth
*cfs_b
)
4246 /* init_cfs_bandwidth() was not called */
4247 if (!cfs_b
->throttled_cfs_rq
.next
)
4250 hrtimer_cancel(&cfs_b
->period_timer
);
4251 hrtimer_cancel(&cfs_b
->slack_timer
);
4254 static void __maybe_unused
update_runtime_enabled(struct rq
*rq
)
4256 struct cfs_rq
*cfs_rq
;
4258 for_each_leaf_cfs_rq(rq
, cfs_rq
) {
4259 struct cfs_bandwidth
*cfs_b
= &cfs_rq
->tg
->cfs_bandwidth
;
4261 raw_spin_lock(&cfs_b
->lock
);
4262 cfs_rq
->runtime_enabled
= cfs_b
->quota
!= RUNTIME_INF
;
4263 raw_spin_unlock(&cfs_b
->lock
);
4267 static void __maybe_unused
unthrottle_offline_cfs_rqs(struct rq
*rq
)
4269 struct cfs_rq
*cfs_rq
;
4271 for_each_leaf_cfs_rq(rq
, cfs_rq
) {
4272 if (!cfs_rq
->runtime_enabled
)
4276 * clock_task is not advancing so we just need to make sure
4277 * there's some valid quota amount
4279 cfs_rq
->runtime_remaining
= 1;
4281 * Offline rq is schedulable till cpu is completely disabled
4282 * in take_cpu_down(), so we prevent new cfs throttling here.
4284 cfs_rq
->runtime_enabled
= 0;
4286 if (cfs_rq_throttled(cfs_rq
))
4287 unthrottle_cfs_rq(cfs_rq
);
4291 #else /* CONFIG_CFS_BANDWIDTH */
4292 static inline u64
cfs_rq_clock_task(struct cfs_rq
*cfs_rq
)
4294 return rq_clock_task(rq_of(cfs_rq
));
4297 static void account_cfs_rq_runtime(struct cfs_rq
*cfs_rq
, u64 delta_exec
) {}
4298 static bool check_cfs_rq_runtime(struct cfs_rq
*cfs_rq
) { return false; }
4299 static void check_enqueue_throttle(struct cfs_rq
*cfs_rq
) {}
4300 static __always_inline
void return_cfs_rq_runtime(struct cfs_rq
*cfs_rq
) {}
4302 static inline int cfs_rq_throttled(struct cfs_rq
*cfs_rq
)
4307 static inline int throttled_hierarchy(struct cfs_rq
*cfs_rq
)
4312 static inline int throttled_lb_pair(struct task_group
*tg
,
4313 int src_cpu
, int dest_cpu
)
4318 void init_cfs_bandwidth(struct cfs_bandwidth
*cfs_b
) {}
4320 #ifdef CONFIG_FAIR_GROUP_SCHED
4321 static void init_cfs_rq_runtime(struct cfs_rq
*cfs_rq
) {}
4324 static inline struct cfs_bandwidth
*tg_cfs_bandwidth(struct task_group
*tg
)
4328 static inline void destroy_cfs_bandwidth(struct cfs_bandwidth
*cfs_b
) {}
4329 static inline void update_runtime_enabled(struct rq
*rq
) {}
4330 static inline void unthrottle_offline_cfs_rqs(struct rq
*rq
) {}
4332 #endif /* CONFIG_CFS_BANDWIDTH */
4334 /**************************************************
4335 * CFS operations on tasks:
4338 #ifdef CONFIG_SCHED_HRTICK
4339 static void hrtick_start_fair(struct rq
*rq
, struct task_struct
*p
)
4341 struct sched_entity
*se
= &p
->se
;
4342 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
4344 WARN_ON(task_rq(p
) != rq
);
4346 if (cfs_rq
->nr_running
> 1) {
4347 u64 slice
= sched_slice(cfs_rq
, se
);
4348 u64 ran
= se
->sum_exec_runtime
- se
->prev_sum_exec_runtime
;
4349 s64 delta
= slice
- ran
;
4356 hrtick_start(rq
, delta
);
4361 * called from enqueue/dequeue and updates the hrtick when the
4362 * current task is from our class and nr_running is low enough
4365 static void hrtick_update(struct rq
*rq
)
4367 struct task_struct
*curr
= rq
->curr
;
4369 if (!hrtick_enabled(rq
) || curr
->sched_class
!= &fair_sched_class
)
4372 if (cfs_rq_of(&curr
->se
)->nr_running
< sched_nr_latency
)
4373 hrtick_start_fair(rq
, curr
);
4375 #else /* !CONFIG_SCHED_HRTICK */
4377 hrtick_start_fair(struct rq
*rq
, struct task_struct
*p
)
4381 static inline void hrtick_update(struct rq
*rq
)
4387 * The enqueue_task method is called before nr_running is
4388 * increased. Here we update the fair scheduling stats and
4389 * then put the task into the rbtree:
4392 enqueue_task_fair(struct rq
*rq
, struct task_struct
*p
, int flags
)
4394 struct cfs_rq
*cfs_rq
;
4395 struct sched_entity
*se
= &p
->se
;
4397 for_each_sched_entity(se
) {
4400 cfs_rq
= cfs_rq_of(se
);
4401 enqueue_entity(cfs_rq
, se
, flags
);
4404 * end evaluation on encountering a throttled cfs_rq
4406 * note: in the case of encountering a throttled cfs_rq we will
4407 * post the final h_nr_running increment below.
4409 if (cfs_rq_throttled(cfs_rq
))
4411 cfs_rq
->h_nr_running
++;
4413 flags
= ENQUEUE_WAKEUP
;
4416 for_each_sched_entity(se
) {
4417 cfs_rq
= cfs_rq_of(se
);
4418 cfs_rq
->h_nr_running
++;
4420 if (cfs_rq_throttled(cfs_rq
))
4423 update_load_avg(se
, 1);
4424 update_cfs_shares(cfs_rq
);
4428 add_nr_running(rq
, 1);
4433 static void set_next_buddy(struct sched_entity
*se
);
4436 * The dequeue_task method is called before nr_running is
4437 * decreased. We remove the task from the rbtree and
4438 * update the fair scheduling stats:
4440 static void dequeue_task_fair(struct rq
*rq
, struct task_struct
*p
, int flags
)
4442 struct cfs_rq
*cfs_rq
;
4443 struct sched_entity
*se
= &p
->se
;
4444 int task_sleep
= flags
& DEQUEUE_SLEEP
;
4446 for_each_sched_entity(se
) {
4447 cfs_rq
= cfs_rq_of(se
);
4448 dequeue_entity(cfs_rq
, se
, flags
);
4451 * end evaluation on encountering a throttled cfs_rq
4453 * note: in the case of encountering a throttled cfs_rq we will
4454 * post the final h_nr_running decrement below.
4456 if (cfs_rq_throttled(cfs_rq
))
4458 cfs_rq
->h_nr_running
--;
4460 /* Don't dequeue parent if it has other entities besides us */
4461 if (cfs_rq
->load
.weight
) {
4463 * Bias pick_next to pick a task from this cfs_rq, as
4464 * p is sleeping when it is within its sched_slice.
4466 if (task_sleep
&& parent_entity(se
))
4467 set_next_buddy(parent_entity(se
));
4469 /* avoid re-evaluating load for this entity */
4470 se
= parent_entity(se
);
4473 flags
|= DEQUEUE_SLEEP
;
4476 for_each_sched_entity(se
) {
4477 cfs_rq
= cfs_rq_of(se
);
4478 cfs_rq
->h_nr_running
--;
4480 if (cfs_rq_throttled(cfs_rq
))
4483 update_load_avg(se
, 1);
4484 update_cfs_shares(cfs_rq
);
4488 sub_nr_running(rq
, 1);
4494 #ifdef CONFIG_NO_HZ_COMMON
4496 * per rq 'load' arrray crap; XXX kill this.
4500 * The exact cpuload calculated at every tick would be:
4502 * load' = (1 - 1/2^i) * load + (1/2^i) * cur_load
4504 * If a cpu misses updates for n ticks (as it was idle) and update gets
4505 * called on the n+1-th tick when cpu may be busy, then we have:
4507 * load_n = (1 - 1/2^i)^n * load_0
4508 * load_n+1 = (1 - 1/2^i) * load_n + (1/2^i) * cur_load
4510 * decay_load_missed() below does efficient calculation of
4512 * load' = (1 - 1/2^i)^n * load
4514 * Because x^(n+m) := x^n * x^m we can decompose any x^n in power-of-2 factors.
4515 * This allows us to precompute the above in said factors, thereby allowing the
4516 * reduction of an arbitrary n in O(log_2 n) steps. (See also
4517 * fixed_power_int())
4519 * The calculation is approximated on a 128 point scale.
4521 #define DEGRADE_SHIFT 7
4523 static const u8 degrade_zero_ticks
[CPU_LOAD_IDX_MAX
] = {0, 8, 32, 64, 128};
4524 static const u8 degrade_factor
[CPU_LOAD_IDX_MAX
][DEGRADE_SHIFT
+ 1] = {
4525 { 0, 0, 0, 0, 0, 0, 0, 0 },
4526 { 64, 32, 8, 0, 0, 0, 0, 0 },
4527 { 96, 72, 40, 12, 1, 0, 0, 0 },
4528 { 112, 98, 75, 43, 15, 1, 0, 0 },
4529 { 120, 112, 98, 76, 45, 16, 2, 0 }
4533 * Update cpu_load for any missed ticks, due to tickless idle. The backlog
4534 * would be when CPU is idle and so we just decay the old load without
4535 * adding any new load.
4537 static unsigned long
4538 decay_load_missed(unsigned long load
, unsigned long missed_updates
, int idx
)
4542 if (!missed_updates
)
4545 if (missed_updates
>= degrade_zero_ticks
[idx
])
4549 return load
>> missed_updates
;
4551 while (missed_updates
) {
4552 if (missed_updates
% 2)
4553 load
= (load
* degrade_factor
[idx
][j
]) >> DEGRADE_SHIFT
;
4555 missed_updates
>>= 1;
4560 #endif /* CONFIG_NO_HZ_COMMON */
4563 * __cpu_load_update - update the rq->cpu_load[] statistics
4564 * @this_rq: The rq to update statistics for
4565 * @this_load: The current load
4566 * @pending_updates: The number of missed updates
4568 * Update rq->cpu_load[] statistics. This function is usually called every
4569 * scheduler tick (TICK_NSEC).
4571 * This function computes a decaying average:
4573 * load[i]' = (1 - 1/2^i) * load[i] + (1/2^i) * load
4575 * Because of NOHZ it might not get called on every tick which gives need for
4576 * the @pending_updates argument.
4578 * load[i]_n = (1 - 1/2^i) * load[i]_n-1 + (1/2^i) * load_n-1
4579 * = A * load[i]_n-1 + B ; A := (1 - 1/2^i), B := (1/2^i) * load
4580 * = A * (A * load[i]_n-2 + B) + B
4581 * = A * (A * (A * load[i]_n-3 + B) + B) + B
4582 * = A^3 * load[i]_n-3 + (A^2 + A + 1) * B
4583 * = A^n * load[i]_0 + (A^(n-1) + A^(n-2) + ... + 1) * B
4584 * = A^n * load[i]_0 + ((1 - A^n) / (1 - A)) * B
4585 * = (1 - 1/2^i)^n * (load[i]_0 - load) + load
4587 * In the above we've assumed load_n := load, which is true for NOHZ_FULL as
4588 * any change in load would have resulted in the tick being turned back on.
4590 * For regular NOHZ, this reduces to:
4592 * load[i]_n = (1 - 1/2^i)^n * load[i]_0
4594 * see decay_load_misses(). For NOHZ_FULL we get to subtract and add the extra
4597 static void cpu_load_update(struct rq
*this_rq
, unsigned long this_load
,
4598 unsigned long pending_updates
)
4600 unsigned long __maybe_unused tickless_load
= this_rq
->cpu_load
[0];
4603 this_rq
->nr_load_updates
++;
4605 /* Update our load: */
4606 this_rq
->cpu_load
[0] = this_load
; /* Fasttrack for idx 0 */
4607 for (i
= 1, scale
= 2; i
< CPU_LOAD_IDX_MAX
; i
++, scale
+= scale
) {
4608 unsigned long old_load
, new_load
;
4610 /* scale is effectively 1 << i now, and >> i divides by scale */
4612 old_load
= this_rq
->cpu_load
[i
];
4613 #ifdef CONFIG_NO_HZ_COMMON
4614 old_load
= decay_load_missed(old_load
, pending_updates
- 1, i
);
4615 if (tickless_load
) {
4616 old_load
-= decay_load_missed(tickless_load
, pending_updates
- 1, i
);
4618 * old_load can never be a negative value because a
4619 * decayed tickless_load cannot be greater than the
4620 * original tickless_load.
4622 old_load
+= tickless_load
;
4625 new_load
= this_load
;
4627 * Round up the averaging division if load is increasing. This
4628 * prevents us from getting stuck on 9 if the load is 10, for
4631 if (new_load
> old_load
)
4632 new_load
+= scale
- 1;
4634 this_rq
->cpu_load
[i
] = (old_load
* (scale
- 1) + new_load
) >> i
;
4637 sched_avg_update(this_rq
);
4640 /* Used instead of source_load when we know the type == 0 */
4641 static unsigned long weighted_cpuload(const int cpu
)
4643 return cfs_rq_runnable_load_avg(&cpu_rq(cpu
)->cfs
);
4646 #ifdef CONFIG_NO_HZ_COMMON
4648 * There is no sane way to deal with nohz on smp when using jiffies because the
4649 * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading
4650 * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}.
4652 * Therefore we need to avoid the delta approach from the regular tick when
4653 * possible since that would seriously skew the load calculation. This is why we
4654 * use cpu_load_update_periodic() for CPUs out of nohz. However we'll rely on
4655 * jiffies deltas for updates happening while in nohz mode (idle ticks, idle
4656 * loop exit, nohz_idle_balance, nohz full exit...)
4658 * This means we might still be one tick off for nohz periods.
4661 static void cpu_load_update_nohz(struct rq
*this_rq
,
4662 unsigned long curr_jiffies
,
4665 unsigned long pending_updates
;
4667 pending_updates
= curr_jiffies
- this_rq
->last_load_update_tick
;
4668 if (pending_updates
) {
4669 this_rq
->last_load_update_tick
= curr_jiffies
;
4671 * In the regular NOHZ case, we were idle, this means load 0.
4672 * In the NOHZ_FULL case, we were non-idle, we should consider
4673 * its weighted load.
4675 cpu_load_update(this_rq
, load
, pending_updates
);
4680 * Called from nohz_idle_balance() to update the load ratings before doing the
4683 static void cpu_load_update_idle(struct rq
*this_rq
)
4686 * bail if there's load or we're actually up-to-date.
4688 if (weighted_cpuload(cpu_of(this_rq
)))
4691 cpu_load_update_nohz(this_rq
, READ_ONCE(jiffies
), 0);
4695 * Record CPU load on nohz entry so we know the tickless load to account
4696 * on nohz exit. cpu_load[0] happens then to be updated more frequently
4697 * than other cpu_load[idx] but it should be fine as cpu_load readers
4698 * shouldn't rely into synchronized cpu_load[*] updates.
4700 void cpu_load_update_nohz_start(void)
4702 struct rq
*this_rq
= this_rq();
4705 * This is all lockless but should be fine. If weighted_cpuload changes
4706 * concurrently we'll exit nohz. And cpu_load write can race with
4707 * cpu_load_update_idle() but both updater would be writing the same.
4709 this_rq
->cpu_load
[0] = weighted_cpuload(cpu_of(this_rq
));
4713 * Account the tickless load in the end of a nohz frame.
4715 void cpu_load_update_nohz_stop(void)
4717 unsigned long curr_jiffies
= READ_ONCE(jiffies
);
4718 struct rq
*this_rq
= this_rq();
4721 if (curr_jiffies
== this_rq
->last_load_update_tick
)
4724 load
= weighted_cpuload(cpu_of(this_rq
));
4725 raw_spin_lock(&this_rq
->lock
);
4726 cpu_load_update_nohz(this_rq
, curr_jiffies
, load
);
4727 raw_spin_unlock(&this_rq
->lock
);
4729 #else /* !CONFIG_NO_HZ_COMMON */
4730 static inline void cpu_load_update_nohz(struct rq
*this_rq
,
4731 unsigned long curr_jiffies
,
4732 unsigned long load
) { }
4733 #endif /* CONFIG_NO_HZ_COMMON */
4735 static void cpu_load_update_periodic(struct rq
*this_rq
, unsigned long load
)
4737 #ifdef CONFIG_NO_HZ_COMMON
4738 /* See the mess around cpu_load_update_nohz(). */
4739 this_rq
->last_load_update_tick
= READ_ONCE(jiffies
);
4741 cpu_load_update(this_rq
, load
, 1);
4745 * Called from scheduler_tick()
4747 void cpu_load_update_active(struct rq
*this_rq
)
4749 unsigned long load
= weighted_cpuload(cpu_of(this_rq
));
4751 if (tick_nohz_tick_stopped())
4752 cpu_load_update_nohz(this_rq
, READ_ONCE(jiffies
), load
);
4754 cpu_load_update_periodic(this_rq
, load
);
4758 * Return a low guess at the load of a migration-source cpu weighted
4759 * according to the scheduling class and "nice" value.
4761 * We want to under-estimate the load of migration sources, to
4762 * balance conservatively.
4764 static unsigned long source_load(int cpu
, int type
)
4766 struct rq
*rq
= cpu_rq(cpu
);
4767 unsigned long total
= weighted_cpuload(cpu
);
4769 if (type
== 0 || !sched_feat(LB_BIAS
))
4772 return min(rq
->cpu_load
[type
-1], total
);
4776 * Return a high guess at the load of a migration-target cpu weighted
4777 * according to the scheduling class and "nice" value.
4779 static unsigned long target_load(int cpu
, int type
)
4781 struct rq
*rq
= cpu_rq(cpu
);
4782 unsigned long total
= weighted_cpuload(cpu
);
4784 if (type
== 0 || !sched_feat(LB_BIAS
))
4787 return max(rq
->cpu_load
[type
-1], total
);
4790 static unsigned long capacity_of(int cpu
)
4792 return cpu_rq(cpu
)->cpu_capacity
;
4795 static unsigned long capacity_orig_of(int cpu
)
4797 return cpu_rq(cpu
)->cpu_capacity_orig
;
4800 static unsigned long cpu_avg_load_per_task(int cpu
)
4802 struct rq
*rq
= cpu_rq(cpu
);
4803 unsigned long nr_running
= READ_ONCE(rq
->cfs
.h_nr_running
);
4804 unsigned long load_avg
= weighted_cpuload(cpu
);
4807 return load_avg
/ nr_running
;
4812 static void record_wakee(struct task_struct
*p
)
4815 * Rough decay (wiping) for cost saving, don't worry
4816 * about the boundary, really active task won't care
4819 if (time_after(jiffies
, current
->wakee_flip_decay_ts
+ HZ
)) {
4820 current
->wakee_flips
>>= 1;
4821 current
->wakee_flip_decay_ts
= jiffies
;
4824 if (current
->last_wakee
!= p
) {
4825 current
->last_wakee
= p
;
4826 current
->wakee_flips
++;
4830 static void task_waking_fair(struct task_struct
*p
)
4832 struct sched_entity
*se
= &p
->se
;
4833 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
4836 #ifndef CONFIG_64BIT
4837 u64 min_vruntime_copy
;
4840 min_vruntime_copy
= cfs_rq
->min_vruntime_copy
;
4842 min_vruntime
= cfs_rq
->min_vruntime
;
4843 } while (min_vruntime
!= min_vruntime_copy
);
4845 min_vruntime
= cfs_rq
->min_vruntime
;
4848 se
->vruntime
-= min_vruntime
;
4852 #ifdef CONFIG_FAIR_GROUP_SCHED
4854 * effective_load() calculates the load change as seen from the root_task_group
4856 * Adding load to a group doesn't make a group heavier, but can cause movement
4857 * of group shares between cpus. Assuming the shares were perfectly aligned one
4858 * can calculate the shift in shares.
4860 * Calculate the effective load difference if @wl is added (subtracted) to @tg
4861 * on this @cpu and results in a total addition (subtraction) of @wg to the
4862 * total group weight.
4864 * Given a runqueue weight distribution (rw_i) we can compute a shares
4865 * distribution (s_i) using:
4867 * s_i = rw_i / \Sum rw_j (1)
4869 * Suppose we have 4 CPUs and our @tg is a direct child of the root group and
4870 * has 7 equal weight tasks, distributed as below (rw_i), with the resulting
4871 * shares distribution (s_i):
4873 * rw_i = { 2, 4, 1, 0 }
4874 * s_i = { 2/7, 4/7, 1/7, 0 }
4876 * As per wake_affine() we're interested in the load of two CPUs (the CPU the
4877 * task used to run on and the CPU the waker is running on), we need to
4878 * compute the effect of waking a task on either CPU and, in case of a sync
4879 * wakeup, compute the effect of the current task going to sleep.
4881 * So for a change of @wl to the local @cpu with an overall group weight change
4882 * of @wl we can compute the new shares distribution (s'_i) using:
4884 * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2)
4886 * Suppose we're interested in CPUs 0 and 1, and want to compute the load
4887 * differences in waking a task to CPU 0. The additional task changes the
4888 * weight and shares distributions like:
4890 * rw'_i = { 3, 4, 1, 0 }
4891 * s'_i = { 3/8, 4/8, 1/8, 0 }
4893 * We can then compute the difference in effective weight by using:
4895 * dw_i = S * (s'_i - s_i) (3)
4897 * Where 'S' is the group weight as seen by its parent.
4899 * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7)
4900 * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 -
4901 * 4/7) times the weight of the group.
4903 static long effective_load(struct task_group
*tg
, int cpu
, long wl
, long wg
)
4905 struct sched_entity
*se
= tg
->se
[cpu
];
4907 if (!tg
->parent
) /* the trivial, non-cgroup case */
4910 for_each_sched_entity(se
) {
4916 * W = @wg + \Sum rw_j
4918 W
= wg
+ calc_tg_weight(tg
, se
->my_q
);
4923 w
= cfs_rq_load_avg(se
->my_q
) + wl
;
4926 * wl = S * s'_i; see (2)
4929 wl
= (w
* (long)tg
->shares
) / W
;
4934 * Per the above, wl is the new se->load.weight value; since
4935 * those are clipped to [MIN_SHARES, ...) do so now. See
4936 * calc_cfs_shares().
4938 if (wl
< MIN_SHARES
)
4942 * wl = dw_i = S * (s'_i - s_i); see (3)
4944 wl
-= se
->avg
.load_avg
;
4947 * Recursively apply this logic to all parent groups to compute
4948 * the final effective load change on the root group. Since
4949 * only the @tg group gets extra weight, all parent groups can
4950 * only redistribute existing shares. @wl is the shift in shares
4951 * resulting from this level per the above.
4960 static long effective_load(struct task_group
*tg
, int cpu
, long wl
, long wg
)
4968 * Detect M:N waker/wakee relationships via a switching-frequency heuristic.
4969 * A waker of many should wake a different task than the one last awakened
4970 * at a frequency roughly N times higher than one of its wakees. In order
4971 * to determine whether we should let the load spread vs consolodating to
4972 * shared cache, we look for a minimum 'flip' frequency of llc_size in one
4973 * partner, and a factor of lls_size higher frequency in the other. With
4974 * both conditions met, we can be relatively sure that the relationship is
4975 * non-monogamous, with partner count exceeding socket size. Waker/wakee
4976 * being client/server, worker/dispatcher, interrupt source or whatever is
4977 * irrelevant, spread criteria is apparent partner count exceeds socket size.
4979 static int wake_wide(struct task_struct
*p
)
4981 unsigned int master
= current
->wakee_flips
;
4982 unsigned int slave
= p
->wakee_flips
;
4983 int factor
= this_cpu_read(sd_llc_size
);
4986 swap(master
, slave
);
4987 if (slave
< factor
|| master
< slave
* factor
)
4992 static int wake_affine(struct sched_domain
*sd
, struct task_struct
*p
, int sync
)
4994 s64 this_load
, load
;
4995 s64 this_eff_load
, prev_eff_load
;
4996 int idx
, this_cpu
, prev_cpu
;
4997 struct task_group
*tg
;
4998 unsigned long weight
;
5002 this_cpu
= smp_processor_id();
5003 prev_cpu
= task_cpu(p
);
5004 load
= source_load(prev_cpu
, idx
);
5005 this_load
= target_load(this_cpu
, idx
);
5008 * If sync wakeup then subtract the (maximum possible)
5009 * effect of the currently running task from the load
5010 * of the current CPU:
5013 tg
= task_group(current
);
5014 weight
= current
->se
.avg
.load_avg
;
5016 this_load
+= effective_load(tg
, this_cpu
, -weight
, -weight
);
5017 load
+= effective_load(tg
, prev_cpu
, 0, -weight
);
5021 weight
= p
->se
.avg
.load_avg
;
5024 * In low-load situations, where prev_cpu is idle and this_cpu is idle
5025 * due to the sync cause above having dropped this_load to 0, we'll
5026 * always have an imbalance, but there's really nothing you can do
5027 * about that, so that's good too.
5029 * Otherwise check if either cpus are near enough in load to allow this
5030 * task to be woken on this_cpu.
5032 this_eff_load
= 100;
5033 this_eff_load
*= capacity_of(prev_cpu
);
5035 prev_eff_load
= 100 + (sd
->imbalance_pct
- 100) / 2;
5036 prev_eff_load
*= capacity_of(this_cpu
);
5038 if (this_load
> 0) {
5039 this_eff_load
*= this_load
+
5040 effective_load(tg
, this_cpu
, weight
, weight
);
5042 prev_eff_load
*= load
+ effective_load(tg
, prev_cpu
, 0, weight
);
5045 balanced
= this_eff_load
<= prev_eff_load
;
5047 schedstat_inc(p
, se
.statistics
.nr_wakeups_affine_attempts
);
5052 schedstat_inc(sd
, ttwu_move_affine
);
5053 schedstat_inc(p
, se
.statistics
.nr_wakeups_affine
);
5059 * find_idlest_group finds and returns the least busy CPU group within the
5062 static struct sched_group
*
5063 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
,
5064 int this_cpu
, int sd_flag
)
5066 struct sched_group
*idlest
= NULL
, *group
= sd
->groups
;
5067 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
5068 int load_idx
= sd
->forkexec_idx
;
5069 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
5071 if (sd_flag
& SD_BALANCE_WAKE
)
5072 load_idx
= sd
->wake_idx
;
5075 unsigned long load
, avg_load
;
5079 /* Skip over this group if it has no CPUs allowed */
5080 if (!cpumask_intersects(sched_group_cpus(group
),
5081 tsk_cpus_allowed(p
)))
5084 local_group
= cpumask_test_cpu(this_cpu
,
5085 sched_group_cpus(group
));
5087 /* Tally up the load of all CPUs in the group */
5090 for_each_cpu(i
, sched_group_cpus(group
)) {
5091 /* Bias balancing toward cpus of our domain */
5093 load
= source_load(i
, load_idx
);
5095 load
= target_load(i
, load_idx
);
5100 /* Adjust by relative CPU capacity of the group */
5101 avg_load
= (avg_load
* SCHED_CAPACITY_SCALE
) / group
->sgc
->capacity
;
5104 this_load
= avg_load
;
5105 } else if (avg_load
< min_load
) {
5106 min_load
= avg_load
;
5109 } while (group
= group
->next
, group
!= sd
->groups
);
5111 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
5117 * find_idlest_cpu - find the idlest cpu among the cpus in group.
5120 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
5122 unsigned long load
, min_load
= ULONG_MAX
;
5123 unsigned int min_exit_latency
= UINT_MAX
;
5124 u64 latest_idle_timestamp
= 0;
5125 int least_loaded_cpu
= this_cpu
;
5126 int shallowest_idle_cpu
= -1;
5129 /* Traverse only the allowed CPUs */
5130 for_each_cpu_and(i
, sched_group_cpus(group
), tsk_cpus_allowed(p
)) {
5132 struct rq
*rq
= cpu_rq(i
);
5133 struct cpuidle_state
*idle
= idle_get_state(rq
);
5134 if (idle
&& idle
->exit_latency
< min_exit_latency
) {
5136 * We give priority to a CPU whose idle state
5137 * has the smallest exit latency irrespective
5138 * of any idle timestamp.
5140 min_exit_latency
= idle
->exit_latency
;
5141 latest_idle_timestamp
= rq
->idle_stamp
;
5142 shallowest_idle_cpu
= i
;
5143 } else if ((!idle
|| idle
->exit_latency
== min_exit_latency
) &&
5144 rq
->idle_stamp
> latest_idle_timestamp
) {
5146 * If equal or no active idle state, then
5147 * the most recently idled CPU might have
5150 latest_idle_timestamp
= rq
->idle_stamp
;
5151 shallowest_idle_cpu
= i
;
5153 } else if (shallowest_idle_cpu
== -1) {
5154 load
= weighted_cpuload(i
);
5155 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
5157 least_loaded_cpu
= i
;
5162 return shallowest_idle_cpu
!= -1 ? shallowest_idle_cpu
: least_loaded_cpu
;
5166 * Try and locate an idle CPU in the sched_domain.
5168 static int select_idle_sibling(struct task_struct
*p
, int target
)
5170 struct sched_domain
*sd
;
5171 struct sched_group
*sg
;
5172 int i
= task_cpu(p
);
5174 if (idle_cpu(target
))
5178 * If the prevous cpu is cache affine and idle, don't be stupid.
5180 if (i
!= target
&& cpus_share_cache(i
, target
) && idle_cpu(i
))
5184 * Otherwise, iterate the domains and find an eligible idle cpu.
5186 * A completely idle sched group at higher domains is more
5187 * desirable than an idle group at a lower level, because lower
5188 * domains have smaller groups and usually share hardware
5189 * resources which causes tasks to contend on them, e.g. x86
5190 * hyperthread siblings in the lowest domain (SMT) can contend
5191 * on the shared cpu pipeline.
5193 * However, while we prefer idle groups at higher domains
5194 * finding an idle cpu at the lowest domain is still better than
5195 * returning 'target', which we've already established, isn't
5198 sd
= rcu_dereference(per_cpu(sd_llc
, target
));
5199 for_each_lower_domain(sd
) {
5202 if (!cpumask_intersects(sched_group_cpus(sg
),
5203 tsk_cpus_allowed(p
)))
5206 /* Ensure the entire group is idle */
5207 for_each_cpu(i
, sched_group_cpus(sg
)) {
5208 if (i
== target
|| !idle_cpu(i
))
5213 * It doesn't matter which cpu we pick, the
5214 * whole group is idle.
5216 target
= cpumask_first_and(sched_group_cpus(sg
),
5217 tsk_cpus_allowed(p
));
5221 } while (sg
!= sd
->groups
);
5228 * cpu_util returns the amount of capacity of a CPU that is used by CFS
5229 * tasks. The unit of the return value must be the one of capacity so we can
5230 * compare the utilization with the capacity of the CPU that is available for
5231 * CFS task (ie cpu_capacity).
5233 * cfs_rq.avg.util_avg is the sum of running time of runnable tasks plus the
5234 * recent utilization of currently non-runnable tasks on a CPU. It represents
5235 * the amount of utilization of a CPU in the range [0..capacity_orig] where
5236 * capacity_orig is the cpu_capacity available at the highest frequency
5237 * (arch_scale_freq_capacity()).
5238 * The utilization of a CPU converges towards a sum equal to or less than the
5239 * current capacity (capacity_curr <= capacity_orig) of the CPU because it is
5240 * the running time on this CPU scaled by capacity_curr.
5242 * Nevertheless, cfs_rq.avg.util_avg can be higher than capacity_curr or even
5243 * higher than capacity_orig because of unfortunate rounding in
5244 * cfs.avg.util_avg or just after migrating tasks and new task wakeups until
5245 * the average stabilizes with the new running time. We need to check that the
5246 * utilization stays within the range of [0..capacity_orig] and cap it if
5247 * necessary. Without utilization capping, a group could be seen as overloaded
5248 * (CPU0 utilization at 121% + CPU1 utilization at 80%) whereas CPU1 has 20% of
5249 * available capacity. We allow utilization to overshoot capacity_curr (but not
5250 * capacity_orig) as it useful for predicting the capacity required after task
5251 * migrations (scheduler-driven DVFS).
5253 static int cpu_util(int cpu
)
5255 unsigned long util
= cpu_rq(cpu
)->cfs
.avg
.util_avg
;
5256 unsigned long capacity
= capacity_orig_of(cpu
);
5258 return (util
>= capacity
) ? capacity
: util
;
5262 * select_task_rq_fair: Select target runqueue for the waking task in domains
5263 * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE,
5264 * SD_BALANCE_FORK, or SD_BALANCE_EXEC.
5266 * Balances load by selecting the idlest cpu in the idlest group, or under
5267 * certain conditions an idle sibling cpu if the domain has SD_WAKE_AFFINE set.
5269 * Returns the target cpu number.
5271 * preempt must be disabled.
5274 select_task_rq_fair(struct task_struct
*p
, int prev_cpu
, int sd_flag
, int wake_flags
)
5276 struct sched_domain
*tmp
, *affine_sd
= NULL
, *sd
= NULL
;
5277 int cpu
= smp_processor_id();
5278 int new_cpu
= prev_cpu
;
5279 int want_affine
= 0;
5280 int sync
= wake_flags
& WF_SYNC
;
5282 if (sd_flag
& SD_BALANCE_WAKE
)
5283 want_affine
= !wake_wide(p
) && cpumask_test_cpu(cpu
, tsk_cpus_allowed(p
));
5286 for_each_domain(cpu
, tmp
) {
5287 if (!(tmp
->flags
& SD_LOAD_BALANCE
))
5291 * If both cpu and prev_cpu are part of this domain,
5292 * cpu is a valid SD_WAKE_AFFINE target.
5294 if (want_affine
&& (tmp
->flags
& SD_WAKE_AFFINE
) &&
5295 cpumask_test_cpu(prev_cpu
, sched_domain_span(tmp
))) {
5300 if (tmp
->flags
& sd_flag
)
5302 else if (!want_affine
)
5307 sd
= NULL
; /* Prefer wake_affine over balance flags */
5308 if (cpu
!= prev_cpu
&& wake_affine(affine_sd
, p
, sync
))
5313 if (sd_flag
& SD_BALANCE_WAKE
) /* XXX always ? */
5314 new_cpu
= select_idle_sibling(p
, new_cpu
);
5317 struct sched_group
*group
;
5320 if (!(sd
->flags
& sd_flag
)) {
5325 group
= find_idlest_group(sd
, p
, cpu
, sd_flag
);
5331 new_cpu
= find_idlest_cpu(group
, p
, cpu
);
5332 if (new_cpu
== -1 || new_cpu
== cpu
) {
5333 /* Now try balancing at a lower domain level of cpu */
5338 /* Now try balancing at a lower domain level of new_cpu */
5340 weight
= sd
->span_weight
;
5342 for_each_domain(cpu
, tmp
) {
5343 if (weight
<= tmp
->span_weight
)
5345 if (tmp
->flags
& sd_flag
)
5348 /* while loop will break here if sd == NULL */
5356 * Called immediately before a task is migrated to a new cpu; task_cpu(p) and
5357 * cfs_rq_of(p) references at time of call are still valid and identify the
5358 * previous cpu. The caller guarantees p->pi_lock or task_rq(p)->lock is held.
5360 static void migrate_task_rq_fair(struct task_struct
*p
)
5363 * We are supposed to update the task to "current" time, then its up to date
5364 * and ready to go to new CPU/cfs_rq. But we have difficulty in getting
5365 * what current time is, so simply throw away the out-of-date time. This
5366 * will result in the wakee task is less decayed, but giving the wakee more
5367 * load sounds not bad.
5369 remove_entity_load_avg(&p
->se
);
5371 /* Tell new CPU we are migrated */
5372 p
->se
.avg
.last_update_time
= 0;
5374 /* We have migrated, no longer consider this task hot */
5375 p
->se
.exec_start
= 0;
5378 static void task_dead_fair(struct task_struct
*p
)
5380 remove_entity_load_avg(&p
->se
);
5382 #endif /* CONFIG_SMP */
5384 static unsigned long
5385 wakeup_gran(struct sched_entity
*curr
, struct sched_entity
*se
)
5387 unsigned long gran
= sysctl_sched_wakeup_granularity
;
5390 * Since its curr running now, convert the gran from real-time
5391 * to virtual-time in his units.
5393 * By using 'se' instead of 'curr' we penalize light tasks, so
5394 * they get preempted easier. That is, if 'se' < 'curr' then
5395 * the resulting gran will be larger, therefore penalizing the
5396 * lighter, if otoh 'se' > 'curr' then the resulting gran will
5397 * be smaller, again penalizing the lighter task.
5399 * This is especially important for buddies when the leftmost
5400 * task is higher priority than the buddy.
5402 return calc_delta_fair(gran
, se
);
5406 * Should 'se' preempt 'curr'.
5420 wakeup_preempt_entity(struct sched_entity
*curr
, struct sched_entity
*se
)
5422 s64 gran
, vdiff
= curr
->vruntime
- se
->vruntime
;
5427 gran
= wakeup_gran(curr
, se
);
5434 static void set_last_buddy(struct sched_entity
*se
)
5436 if (entity_is_task(se
) && unlikely(task_of(se
)->policy
== SCHED_IDLE
))
5439 for_each_sched_entity(se
)
5440 cfs_rq_of(se
)->last
= se
;
5443 static void set_next_buddy(struct sched_entity
*se
)
5445 if (entity_is_task(se
) && unlikely(task_of(se
)->policy
== SCHED_IDLE
))
5448 for_each_sched_entity(se
)
5449 cfs_rq_of(se
)->next
= se
;
5452 static void set_skip_buddy(struct sched_entity
*se
)
5454 for_each_sched_entity(se
)
5455 cfs_rq_of(se
)->skip
= se
;
5459 * Preempt the current task with a newly woken task if needed:
5461 static void check_preempt_wakeup(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
5463 struct task_struct
*curr
= rq
->curr
;
5464 struct sched_entity
*se
= &curr
->se
, *pse
= &p
->se
;
5465 struct cfs_rq
*cfs_rq
= task_cfs_rq(curr
);
5466 int scale
= cfs_rq
->nr_running
>= sched_nr_latency
;
5467 int next_buddy_marked
= 0;
5469 if (unlikely(se
== pse
))
5473 * This is possible from callers such as attach_tasks(), in which we
5474 * unconditionally check_prempt_curr() after an enqueue (which may have
5475 * lead to a throttle). This both saves work and prevents false
5476 * next-buddy nomination below.
5478 if (unlikely(throttled_hierarchy(cfs_rq_of(pse
))))
5481 if (sched_feat(NEXT_BUDDY
) && scale
&& !(wake_flags
& WF_FORK
)) {
5482 set_next_buddy(pse
);
5483 next_buddy_marked
= 1;
5487 * We can come here with TIF_NEED_RESCHED already set from new task
5490 * Note: this also catches the edge-case of curr being in a throttled
5491 * group (e.g. via set_curr_task), since update_curr() (in the
5492 * enqueue of curr) will have resulted in resched being set. This
5493 * prevents us from potentially nominating it as a false LAST_BUDDY
5496 if (test_tsk_need_resched(curr
))
5499 /* Idle tasks are by definition preempted by non-idle tasks. */
5500 if (unlikely(curr
->policy
== SCHED_IDLE
) &&
5501 likely(p
->policy
!= SCHED_IDLE
))
5505 * Batch and idle tasks do not preempt non-idle tasks (their preemption
5506 * is driven by the tick):
5508 if (unlikely(p
->policy
!= SCHED_NORMAL
) || !sched_feat(WAKEUP_PREEMPTION
))
5511 find_matching_se(&se
, &pse
);
5512 update_curr(cfs_rq_of(se
));
5514 if (wakeup_preempt_entity(se
, pse
) == 1) {
5516 * Bias pick_next to pick the sched entity that is
5517 * triggering this preemption.
5519 if (!next_buddy_marked
)
5520 set_next_buddy(pse
);
5529 * Only set the backward buddy when the current task is still
5530 * on the rq. This can happen when a wakeup gets interleaved
5531 * with schedule on the ->pre_schedule() or idle_balance()
5532 * point, either of which can * drop the rq lock.
5534 * Also, during early boot the idle thread is in the fair class,
5535 * for obvious reasons its a bad idea to schedule back to it.
5537 if (unlikely(!se
->on_rq
|| curr
== rq
->idle
))
5540 if (sched_feat(LAST_BUDDY
) && scale
&& entity_is_task(se
))
5544 static struct task_struct
*
5545 pick_next_task_fair(struct rq
*rq
, struct task_struct
*prev
)
5547 struct cfs_rq
*cfs_rq
= &rq
->cfs
;
5548 struct sched_entity
*se
;
5549 struct task_struct
*p
;
5553 #ifdef CONFIG_FAIR_GROUP_SCHED
5554 if (!cfs_rq
->nr_running
)
5557 if (prev
->sched_class
!= &fair_sched_class
)
5561 * Because of the set_next_buddy() in dequeue_task_fair() it is rather
5562 * likely that a next task is from the same cgroup as the current.
5564 * Therefore attempt to avoid putting and setting the entire cgroup
5565 * hierarchy, only change the part that actually changes.
5569 struct sched_entity
*curr
= cfs_rq
->curr
;
5572 * Since we got here without doing put_prev_entity() we also
5573 * have to consider cfs_rq->curr. If it is still a runnable
5574 * entity, update_curr() will update its vruntime, otherwise
5575 * forget we've ever seen it.
5579 update_curr(cfs_rq
);
5584 * This call to check_cfs_rq_runtime() will do the
5585 * throttle and dequeue its entity in the parent(s).
5586 * Therefore the 'simple' nr_running test will indeed
5589 if (unlikely(check_cfs_rq_runtime(cfs_rq
)))
5593 se
= pick_next_entity(cfs_rq
, curr
);
5594 cfs_rq
= group_cfs_rq(se
);
5600 * Since we haven't yet done put_prev_entity and if the selected task
5601 * is a different task than we started out with, try and touch the
5602 * least amount of cfs_rqs.
5605 struct sched_entity
*pse
= &prev
->se
;
5607 while (!(cfs_rq
= is_same_group(se
, pse
))) {
5608 int se_depth
= se
->depth
;
5609 int pse_depth
= pse
->depth
;
5611 if (se_depth
<= pse_depth
) {
5612 put_prev_entity(cfs_rq_of(pse
), pse
);
5613 pse
= parent_entity(pse
);
5615 if (se_depth
>= pse_depth
) {
5616 set_next_entity(cfs_rq_of(se
), se
);
5617 se
= parent_entity(se
);
5621 put_prev_entity(cfs_rq
, pse
);
5622 set_next_entity(cfs_rq
, se
);
5625 if (hrtick_enabled(rq
))
5626 hrtick_start_fair(rq
, p
);
5633 if (!cfs_rq
->nr_running
)
5636 put_prev_task(rq
, prev
);
5639 se
= pick_next_entity(cfs_rq
, NULL
);
5640 set_next_entity(cfs_rq
, se
);
5641 cfs_rq
= group_cfs_rq(se
);
5646 if (hrtick_enabled(rq
))
5647 hrtick_start_fair(rq
, p
);
5653 * This is OK, because current is on_cpu, which avoids it being picked
5654 * for load-balance and preemption/IRQs are still disabled avoiding
5655 * further scheduler activity on it and we're being very careful to
5656 * re-start the picking loop.
5658 lockdep_unpin_lock(&rq
->lock
);
5659 new_tasks
= idle_balance(rq
);
5660 lockdep_pin_lock(&rq
->lock
);
5662 * Because idle_balance() releases (and re-acquires) rq->lock, it is
5663 * possible for any higher priority task to appear. In that case we
5664 * must re-start the pick_next_entity() loop.
5676 * Account for a descheduled task:
5678 static void put_prev_task_fair(struct rq
*rq
, struct task_struct
*prev
)
5680 struct sched_entity
*se
= &prev
->se
;
5681 struct cfs_rq
*cfs_rq
;
5683 for_each_sched_entity(se
) {
5684 cfs_rq
= cfs_rq_of(se
);
5685 put_prev_entity(cfs_rq
, se
);
5690 * sched_yield() is very simple
5692 * The magic of dealing with the ->skip buddy is in pick_next_entity.
5694 static void yield_task_fair(struct rq
*rq
)
5696 struct task_struct
*curr
= rq
->curr
;
5697 struct cfs_rq
*cfs_rq
= task_cfs_rq(curr
);
5698 struct sched_entity
*se
= &curr
->se
;
5701 * Are we the only task in the tree?
5703 if (unlikely(rq
->nr_running
== 1))
5706 clear_buddies(cfs_rq
, se
);
5708 if (curr
->policy
!= SCHED_BATCH
) {
5709 update_rq_clock(rq
);
5711 * Update run-time statistics of the 'current'.
5713 update_curr(cfs_rq
);
5715 * Tell update_rq_clock() that we've just updated,
5716 * so we don't do microscopic update in schedule()
5717 * and double the fastpath cost.
5719 rq_clock_skip_update(rq
, true);
5725 static bool yield_to_task_fair(struct rq
*rq
, struct task_struct
*p
, bool preempt
)
5727 struct sched_entity
*se
= &p
->se
;
5729 /* throttled hierarchies are not runnable */
5730 if (!se
->on_rq
|| throttled_hierarchy(cfs_rq_of(se
)))
5733 /* Tell the scheduler that we'd really like pse to run next. */
5736 yield_task_fair(rq
);
5742 /**************************************************
5743 * Fair scheduling class load-balancing methods.
5747 * The purpose of load-balancing is to achieve the same basic fairness the
5748 * per-cpu scheduler provides, namely provide a proportional amount of compute
5749 * time to each task. This is expressed in the following equation:
5751 * W_i,n/P_i == W_j,n/P_j for all i,j (1)
5753 * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight
5754 * W_i,0 is defined as:
5756 * W_i,0 = \Sum_j w_i,j (2)
5758 * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight
5759 * is derived from the nice value as per sched_prio_to_weight[].
5761 * The weight average is an exponential decay average of the instantaneous
5764 * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3)
5766 * C_i is the compute capacity of cpu i, typically it is the
5767 * fraction of 'recent' time available for SCHED_OTHER task execution. But it
5768 * can also include other factors [XXX].
5770 * To achieve this balance we define a measure of imbalance which follows
5771 * directly from (1):
5773 * imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j } (4)
5775 * We them move tasks around to minimize the imbalance. In the continuous
5776 * function space it is obvious this converges, in the discrete case we get
5777 * a few fun cases generally called infeasible weight scenarios.
5780 * - infeasible weights;
5781 * - local vs global optima in the discrete case. ]
5786 * In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
5787 * for all i,j solution, we create a tree of cpus that follows the hardware
5788 * topology where each level pairs two lower groups (or better). This results
5789 * in O(log n) layers. Furthermore we reduce the number of cpus going up the
5790 * tree to only the first of the previous level and we decrease the frequency
5791 * of load-balance at each level inv. proportional to the number of cpus in
5797 * \Sum { --- * --- * 2^i } = O(n) (5)
5799 * `- size of each group
5800 * | | `- number of cpus doing load-balance
5802 * `- sum over all levels
5804 * Coupled with a limit on how many tasks we can migrate every balance pass,
5805 * this makes (5) the runtime complexity of the balancer.
5807 * An important property here is that each CPU is still (indirectly) connected
5808 * to every other cpu in at most O(log n) steps:
5810 * The adjacency matrix of the resulting graph is given by:
5813 * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6)
5816 * And you'll find that:
5818 * A^(log_2 n)_i,j != 0 for all i,j (7)
5820 * Showing there's indeed a path between every cpu in at most O(log n) steps.
5821 * The task movement gives a factor of O(m), giving a convergence complexity
5824 * O(nm log n), n := nr_cpus, m := nr_tasks (8)
5829 * In order to avoid CPUs going idle while there's still work to do, new idle
5830 * balancing is more aggressive and has the newly idle cpu iterate up the domain
5831 * tree itself instead of relying on other CPUs to bring it work.
5833 * This adds some complexity to both (5) and (8) but it reduces the total idle
5841 * Cgroups make a horror show out of (2), instead of a simple sum we get:
5844 * W_i,0 = \Sum_j \Prod_k w_k * ----- (9)
5849 * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10)
5851 * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i.
5853 * The big problem is S_k, its a global sum needed to compute a local (W_i)
5856 * [XXX write more on how we solve this.. _after_ merging pjt's patches that
5857 * rewrite all of this once again.]
5860 static unsigned long __read_mostly max_load_balance_interval
= HZ
/10;
5862 enum fbq_type
{ regular
, remote
, all
};
5864 #define LBF_ALL_PINNED 0x01
5865 #define LBF_NEED_BREAK 0x02
5866 #define LBF_DST_PINNED 0x04
5867 #define LBF_SOME_PINNED 0x08
5870 struct sched_domain
*sd
;
5878 struct cpumask
*dst_grpmask
;
5880 enum cpu_idle_type idle
;
5882 /* The set of CPUs under consideration for load-balancing */
5883 struct cpumask
*cpus
;
5888 unsigned int loop_break
;
5889 unsigned int loop_max
;
5891 enum fbq_type fbq_type
;
5892 struct list_head tasks
;
5896 * Is this task likely cache-hot:
5898 static int task_hot(struct task_struct
*p
, struct lb_env
*env
)
5902 lockdep_assert_held(&env
->src_rq
->lock
);
5904 if (p
->sched_class
!= &fair_sched_class
)
5907 if (unlikely(p
->policy
== SCHED_IDLE
))
5911 * Buddy candidates are cache hot:
5913 if (sched_feat(CACHE_HOT_BUDDY
) && env
->dst_rq
->nr_running
&&
5914 (&p
->se
== cfs_rq_of(&p
->se
)->next
||
5915 &p
->se
== cfs_rq_of(&p
->se
)->last
))
5918 if (sysctl_sched_migration_cost
== -1)
5920 if (sysctl_sched_migration_cost
== 0)
5923 delta
= rq_clock_task(env
->src_rq
) - p
->se
.exec_start
;
5925 return delta
< (s64
)sysctl_sched_migration_cost
;
5928 #ifdef CONFIG_NUMA_BALANCING
5930 * Returns 1, if task migration degrades locality
5931 * Returns 0, if task migration improves locality i.e migration preferred.
5932 * Returns -1, if task migration is not affected by locality.
5934 static int migrate_degrades_locality(struct task_struct
*p
, struct lb_env
*env
)
5936 struct numa_group
*numa_group
= rcu_dereference(p
->numa_group
);
5937 unsigned long src_faults
, dst_faults
;
5938 int src_nid
, dst_nid
;
5940 if (!static_branch_likely(&sched_numa_balancing
))
5943 if (!p
->numa_faults
|| !(env
->sd
->flags
& SD_NUMA
))
5946 src_nid
= cpu_to_node(env
->src_cpu
);
5947 dst_nid
= cpu_to_node(env
->dst_cpu
);
5949 if (src_nid
== dst_nid
)
5952 /* Migrating away from the preferred node is always bad. */
5953 if (src_nid
== p
->numa_preferred_nid
) {
5954 if (env
->src_rq
->nr_running
> env
->src_rq
->nr_preferred_running
)
5960 /* Encourage migration to the preferred node. */
5961 if (dst_nid
== p
->numa_preferred_nid
)
5965 src_faults
= group_faults(p
, src_nid
);
5966 dst_faults
= group_faults(p
, dst_nid
);
5968 src_faults
= task_faults(p
, src_nid
);
5969 dst_faults
= task_faults(p
, dst_nid
);
5972 return dst_faults
< src_faults
;
5976 static inline int migrate_degrades_locality(struct task_struct
*p
,
5984 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
5987 int can_migrate_task(struct task_struct
*p
, struct lb_env
*env
)
5991 lockdep_assert_held(&env
->src_rq
->lock
);
5994 * We do not migrate tasks that are:
5995 * 1) throttled_lb_pair, or
5996 * 2) cannot be migrated to this CPU due to cpus_allowed, or
5997 * 3) running (obviously), or
5998 * 4) are cache-hot on their current CPU.
6000 if (throttled_lb_pair(task_group(p
), env
->src_cpu
, env
->dst_cpu
))
6003 if (!cpumask_test_cpu(env
->dst_cpu
, tsk_cpus_allowed(p
))) {
6006 schedstat_inc(p
, se
.statistics
.nr_failed_migrations_affine
);
6008 env
->flags
|= LBF_SOME_PINNED
;
6011 * Remember if this task can be migrated to any other cpu in
6012 * our sched_group. We may want to revisit it if we couldn't
6013 * meet load balance goals by pulling other tasks on src_cpu.
6015 * Also avoid computing new_dst_cpu if we have already computed
6016 * one in current iteration.
6018 if (!env
->dst_grpmask
|| (env
->flags
& LBF_DST_PINNED
))
6021 /* Prevent to re-select dst_cpu via env's cpus */
6022 for_each_cpu_and(cpu
, env
->dst_grpmask
, env
->cpus
) {
6023 if (cpumask_test_cpu(cpu
, tsk_cpus_allowed(p
))) {
6024 env
->flags
|= LBF_DST_PINNED
;
6025 env
->new_dst_cpu
= cpu
;
6033 /* Record that we found atleast one task that could run on dst_cpu */
6034 env
->flags
&= ~LBF_ALL_PINNED
;
6036 if (task_running(env
->src_rq
, p
)) {
6037 schedstat_inc(p
, se
.statistics
.nr_failed_migrations_running
);
6042 * Aggressive migration if:
6043 * 1) destination numa is preferred
6044 * 2) task is cache cold, or
6045 * 3) too many balance attempts have failed.
6047 tsk_cache_hot
= migrate_degrades_locality(p
, env
);
6048 if (tsk_cache_hot
== -1)
6049 tsk_cache_hot
= task_hot(p
, env
);
6051 if (tsk_cache_hot
<= 0 ||
6052 env
->sd
->nr_balance_failed
> env
->sd
->cache_nice_tries
) {
6053 if (tsk_cache_hot
== 1) {
6054 schedstat_inc(env
->sd
, lb_hot_gained
[env
->idle
]);
6055 schedstat_inc(p
, se
.statistics
.nr_forced_migrations
);
6060 schedstat_inc(p
, se
.statistics
.nr_failed_migrations_hot
);
6065 * detach_task() -- detach the task for the migration specified in env
6067 static void detach_task(struct task_struct
*p
, struct lb_env
*env
)
6069 lockdep_assert_held(&env
->src_rq
->lock
);
6071 p
->on_rq
= TASK_ON_RQ_MIGRATING
;
6072 deactivate_task(env
->src_rq
, p
, 0);
6073 set_task_cpu(p
, env
->dst_cpu
);
6077 * detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as
6078 * part of active balancing operations within "domain".
6080 * Returns a task if successful and NULL otherwise.
6082 static struct task_struct
*detach_one_task(struct lb_env
*env
)
6084 struct task_struct
*p
, *n
;
6086 lockdep_assert_held(&env
->src_rq
->lock
);
6088 list_for_each_entry_safe(p
, n
, &env
->src_rq
->cfs_tasks
, se
.group_node
) {
6089 if (!can_migrate_task(p
, env
))
6092 detach_task(p
, env
);
6095 * Right now, this is only the second place where
6096 * lb_gained[env->idle] is updated (other is detach_tasks)
6097 * so we can safely collect stats here rather than
6098 * inside detach_tasks().
6100 schedstat_inc(env
->sd
, lb_gained
[env
->idle
]);
6106 static const unsigned int sched_nr_migrate_break
= 32;
6109 * detach_tasks() -- tries to detach up to imbalance weighted load from
6110 * busiest_rq, as part of a balancing operation within domain "sd".
6112 * Returns number of detached tasks if successful and 0 otherwise.
6114 static int detach_tasks(struct lb_env
*env
)
6116 struct list_head
*tasks
= &env
->src_rq
->cfs_tasks
;
6117 struct task_struct
*p
;
6121 lockdep_assert_held(&env
->src_rq
->lock
);
6123 if (env
->imbalance
<= 0)
6126 while (!list_empty(tasks
)) {
6128 * We don't want to steal all, otherwise we may be treated likewise,
6129 * which could at worst lead to a livelock crash.
6131 if (env
->idle
!= CPU_NOT_IDLE
&& env
->src_rq
->nr_running
<= 1)
6134 p
= list_first_entry(tasks
, struct task_struct
, se
.group_node
);
6137 /* We've more or less seen every task there is, call it quits */
6138 if (env
->loop
> env
->loop_max
)
6141 /* take a breather every nr_migrate tasks */
6142 if (env
->loop
> env
->loop_break
) {
6143 env
->loop_break
+= sched_nr_migrate_break
;
6144 env
->flags
|= LBF_NEED_BREAK
;
6148 if (!can_migrate_task(p
, env
))
6151 load
= task_h_load(p
);
6153 if (sched_feat(LB_MIN
) && load
< 16 && !env
->sd
->nr_balance_failed
)
6156 if ((load
/ 2) > env
->imbalance
)
6159 detach_task(p
, env
);
6160 list_add(&p
->se
.group_node
, &env
->tasks
);
6163 env
->imbalance
-= load
;
6165 #ifdef CONFIG_PREEMPT
6167 * NEWIDLE balancing is a source of latency, so preemptible
6168 * kernels will stop after the first task is detached to minimize
6169 * the critical section.
6171 if (env
->idle
== CPU_NEWLY_IDLE
)
6176 * We only want to steal up to the prescribed amount of
6179 if (env
->imbalance
<= 0)
6184 list_move_tail(&p
->se
.group_node
, tasks
);
6188 * Right now, this is one of only two places we collect this stat
6189 * so we can safely collect detach_one_task() stats here rather
6190 * than inside detach_one_task().
6192 schedstat_add(env
->sd
, lb_gained
[env
->idle
], detached
);
6198 * attach_task() -- attach the task detached by detach_task() to its new rq.
6200 static void attach_task(struct rq
*rq
, struct task_struct
*p
)
6202 lockdep_assert_held(&rq
->lock
);
6204 BUG_ON(task_rq(p
) != rq
);
6205 activate_task(rq
, p
, 0);
6206 p
->on_rq
= TASK_ON_RQ_QUEUED
;
6207 check_preempt_curr(rq
, p
, 0);
6211 * attach_one_task() -- attaches the task returned from detach_one_task() to
6214 static void attach_one_task(struct rq
*rq
, struct task_struct
*p
)
6216 raw_spin_lock(&rq
->lock
);
6218 raw_spin_unlock(&rq
->lock
);
6222 * attach_tasks() -- attaches all tasks detached by detach_tasks() to their
6225 static void attach_tasks(struct lb_env
*env
)
6227 struct list_head
*tasks
= &env
->tasks
;
6228 struct task_struct
*p
;
6230 raw_spin_lock(&env
->dst_rq
->lock
);
6232 while (!list_empty(tasks
)) {
6233 p
= list_first_entry(tasks
, struct task_struct
, se
.group_node
);
6234 list_del_init(&p
->se
.group_node
);
6236 attach_task(env
->dst_rq
, p
);
6239 raw_spin_unlock(&env
->dst_rq
->lock
);
6242 #ifdef CONFIG_FAIR_GROUP_SCHED
6243 static void update_blocked_averages(int cpu
)
6245 struct rq
*rq
= cpu_rq(cpu
);
6246 struct cfs_rq
*cfs_rq
;
6247 unsigned long flags
;
6249 raw_spin_lock_irqsave(&rq
->lock
, flags
);
6250 update_rq_clock(rq
);
6253 * Iterates the task_group tree in a bottom up fashion, see
6254 * list_add_leaf_cfs_rq() for details.
6256 for_each_leaf_cfs_rq(rq
, cfs_rq
) {
6257 /* throttled entities do not contribute to load */
6258 if (throttled_hierarchy(cfs_rq
))
6261 if (update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq
), cfs_rq
, true))
6262 update_tg_load_avg(cfs_rq
, 0);
6264 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
6268 * Compute the hierarchical load factor for cfs_rq and all its ascendants.
6269 * This needs to be done in a top-down fashion because the load of a child
6270 * group is a fraction of its parents load.
6272 static void update_cfs_rq_h_load(struct cfs_rq
*cfs_rq
)
6274 struct rq
*rq
= rq_of(cfs_rq
);
6275 struct sched_entity
*se
= cfs_rq
->tg
->se
[cpu_of(rq
)];
6276 unsigned long now
= jiffies
;
6279 if (cfs_rq
->last_h_load_update
== now
)
6282 cfs_rq
->h_load_next
= NULL
;
6283 for_each_sched_entity(se
) {
6284 cfs_rq
= cfs_rq_of(se
);
6285 cfs_rq
->h_load_next
= se
;
6286 if (cfs_rq
->last_h_load_update
== now
)
6291 cfs_rq
->h_load
= cfs_rq_load_avg(cfs_rq
);
6292 cfs_rq
->last_h_load_update
= now
;
6295 while ((se
= cfs_rq
->h_load_next
) != NULL
) {
6296 load
= cfs_rq
->h_load
;
6297 load
= div64_ul(load
* se
->avg
.load_avg
,
6298 cfs_rq_load_avg(cfs_rq
) + 1);
6299 cfs_rq
= group_cfs_rq(se
);
6300 cfs_rq
->h_load
= load
;
6301 cfs_rq
->last_h_load_update
= now
;
6305 static unsigned long task_h_load(struct task_struct
*p
)
6307 struct cfs_rq
*cfs_rq
= task_cfs_rq(p
);
6309 update_cfs_rq_h_load(cfs_rq
);
6310 return div64_ul(p
->se
.avg
.load_avg
* cfs_rq
->h_load
,
6311 cfs_rq_load_avg(cfs_rq
) + 1);
6314 static inline void update_blocked_averages(int cpu
)
6316 struct rq
*rq
= cpu_rq(cpu
);
6317 struct cfs_rq
*cfs_rq
= &rq
->cfs
;
6318 unsigned long flags
;
6320 raw_spin_lock_irqsave(&rq
->lock
, flags
);
6321 update_rq_clock(rq
);
6322 update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq
), cfs_rq
, true);
6323 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
6326 static unsigned long task_h_load(struct task_struct
*p
)
6328 return p
->se
.avg
.load_avg
;
6332 /********** Helpers for find_busiest_group ************************/
6341 * sg_lb_stats - stats of a sched_group required for load_balancing
6343 struct sg_lb_stats
{
6344 unsigned long avg_load
; /*Avg load across the CPUs of the group */
6345 unsigned long group_load
; /* Total load over the CPUs of the group */
6346 unsigned long sum_weighted_load
; /* Weighted load of group's tasks */
6347 unsigned long load_per_task
;
6348 unsigned long group_capacity
;
6349 unsigned long group_util
; /* Total utilization of the group */
6350 unsigned int sum_nr_running
; /* Nr tasks running in the group */
6351 unsigned int idle_cpus
;
6352 unsigned int group_weight
;
6353 enum group_type group_type
;
6354 int group_no_capacity
;
6355 #ifdef CONFIG_NUMA_BALANCING
6356 unsigned int nr_numa_running
;
6357 unsigned int nr_preferred_running
;
6362 * sd_lb_stats - Structure to store the statistics of a sched_domain
6363 * during load balancing.
6365 struct sd_lb_stats
{
6366 struct sched_group
*busiest
; /* Busiest group in this sd */
6367 struct sched_group
*local
; /* Local group in this sd */
6368 unsigned long total_load
; /* Total load of all groups in sd */
6369 unsigned long total_capacity
; /* Total capacity of all groups in sd */
6370 unsigned long avg_load
; /* Average load across all groups in sd */
6372 struct sg_lb_stats busiest_stat
;/* Statistics of the busiest group */
6373 struct sg_lb_stats local_stat
; /* Statistics of the local group */
6376 static inline void init_sd_lb_stats(struct sd_lb_stats
*sds
)
6379 * Skimp on the clearing to avoid duplicate work. We can avoid clearing
6380 * local_stat because update_sg_lb_stats() does a full clear/assignment.
6381 * We must however clear busiest_stat::avg_load because
6382 * update_sd_pick_busiest() reads this before assignment.
6384 *sds
= (struct sd_lb_stats
){
6388 .total_capacity
= 0UL,
6391 .sum_nr_running
= 0,
6392 .group_type
= group_other
,
6398 * get_sd_load_idx - Obtain the load index for a given sched domain.
6399 * @sd: The sched_domain whose load_idx is to be obtained.
6400 * @idle: The idle status of the CPU for whose sd load_idx is obtained.
6402 * Return: The load index.
6404 static inline int get_sd_load_idx(struct sched_domain
*sd
,
6405 enum cpu_idle_type idle
)
6411 load_idx
= sd
->busy_idx
;
6414 case CPU_NEWLY_IDLE
:
6415 load_idx
= sd
->newidle_idx
;
6418 load_idx
= sd
->idle_idx
;
6425 static unsigned long scale_rt_capacity(int cpu
)
6427 struct rq
*rq
= cpu_rq(cpu
);
6428 u64 total
, used
, age_stamp
, avg
;
6432 * Since we're reading these variables without serialization make sure
6433 * we read them once before doing sanity checks on them.
6435 age_stamp
= READ_ONCE(rq
->age_stamp
);
6436 avg
= READ_ONCE(rq
->rt_avg
);
6437 delta
= __rq_clock_broken(rq
) - age_stamp
;
6439 if (unlikely(delta
< 0))
6442 total
= sched_avg_period() + delta
;
6444 used
= div_u64(avg
, total
);
6446 if (likely(used
< SCHED_CAPACITY_SCALE
))
6447 return SCHED_CAPACITY_SCALE
- used
;
6452 static void update_cpu_capacity(struct sched_domain
*sd
, int cpu
)
6454 unsigned long capacity
= arch_scale_cpu_capacity(sd
, cpu
);
6455 struct sched_group
*sdg
= sd
->groups
;
6457 cpu_rq(cpu
)->cpu_capacity_orig
= capacity
;
6459 capacity
*= scale_rt_capacity(cpu
);
6460 capacity
>>= SCHED_CAPACITY_SHIFT
;
6465 cpu_rq(cpu
)->cpu_capacity
= capacity
;
6466 sdg
->sgc
->capacity
= capacity
;
6469 void update_group_capacity(struct sched_domain
*sd
, int cpu
)
6471 struct sched_domain
*child
= sd
->child
;
6472 struct sched_group
*group
, *sdg
= sd
->groups
;
6473 unsigned long capacity
;
6474 unsigned long interval
;
6476 interval
= msecs_to_jiffies(sd
->balance_interval
);
6477 interval
= clamp(interval
, 1UL, max_load_balance_interval
);
6478 sdg
->sgc
->next_update
= jiffies
+ interval
;
6481 update_cpu_capacity(sd
, cpu
);
6487 if (child
->flags
& SD_OVERLAP
) {
6489 * SD_OVERLAP domains cannot assume that child groups
6490 * span the current group.
6493 for_each_cpu(cpu
, sched_group_cpus(sdg
)) {
6494 struct sched_group_capacity
*sgc
;
6495 struct rq
*rq
= cpu_rq(cpu
);
6498 * build_sched_domains() -> init_sched_groups_capacity()
6499 * gets here before we've attached the domains to the
6502 * Use capacity_of(), which is set irrespective of domains
6503 * in update_cpu_capacity().
6505 * This avoids capacity from being 0 and
6506 * causing divide-by-zero issues on boot.
6508 if (unlikely(!rq
->sd
)) {
6509 capacity
+= capacity_of(cpu
);
6513 sgc
= rq
->sd
->groups
->sgc
;
6514 capacity
+= sgc
->capacity
;
6518 * !SD_OVERLAP domains can assume that child groups
6519 * span the current group.
6522 group
= child
->groups
;
6524 capacity
+= group
->sgc
->capacity
;
6525 group
= group
->next
;
6526 } while (group
!= child
->groups
);
6529 sdg
->sgc
->capacity
= capacity
;
6533 * Check whether the capacity of the rq has been noticeably reduced by side
6534 * activity. The imbalance_pct is used for the threshold.
6535 * Return true is the capacity is reduced
6538 check_cpu_capacity(struct rq
*rq
, struct sched_domain
*sd
)
6540 return ((rq
->cpu_capacity
* sd
->imbalance_pct
) <
6541 (rq
->cpu_capacity_orig
* 100));
6545 * Group imbalance indicates (and tries to solve) the problem where balancing
6546 * groups is inadequate due to tsk_cpus_allowed() constraints.
6548 * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a
6549 * cpumask covering 1 cpu of the first group and 3 cpus of the second group.
6552 * { 0 1 2 3 } { 4 5 6 7 }
6555 * If we were to balance group-wise we'd place two tasks in the first group and
6556 * two tasks in the second group. Clearly this is undesired as it will overload
6557 * cpu 3 and leave one of the cpus in the second group unused.
6559 * The current solution to this issue is detecting the skew in the first group
6560 * by noticing the lower domain failed to reach balance and had difficulty
6561 * moving tasks due to affinity constraints.
6563 * When this is so detected; this group becomes a candidate for busiest; see
6564 * update_sd_pick_busiest(). And calculate_imbalance() and
6565 * find_busiest_group() avoid some of the usual balance conditions to allow it
6566 * to create an effective group imbalance.
6568 * This is a somewhat tricky proposition since the next run might not find the
6569 * group imbalance and decide the groups need to be balanced again. A most
6570 * subtle and fragile situation.
6573 static inline int sg_imbalanced(struct sched_group
*group
)
6575 return group
->sgc
->imbalance
;
6579 * group_has_capacity returns true if the group has spare capacity that could
6580 * be used by some tasks.
6581 * We consider that a group has spare capacity if the * number of task is
6582 * smaller than the number of CPUs or if the utilization is lower than the
6583 * available capacity for CFS tasks.
6584 * For the latter, we use a threshold to stabilize the state, to take into
6585 * account the variance of the tasks' load and to return true if the available
6586 * capacity in meaningful for the load balancer.
6587 * As an example, an available capacity of 1% can appear but it doesn't make
6588 * any benefit for the load balance.
6591 group_has_capacity(struct lb_env
*env
, struct sg_lb_stats
*sgs
)
6593 if (sgs
->sum_nr_running
< sgs
->group_weight
)
6596 if ((sgs
->group_capacity
* 100) >
6597 (sgs
->group_util
* env
->sd
->imbalance_pct
))
6604 * group_is_overloaded returns true if the group has more tasks than it can
6606 * group_is_overloaded is not equals to !group_has_capacity because a group
6607 * with the exact right number of tasks, has no more spare capacity but is not
6608 * overloaded so both group_has_capacity and group_is_overloaded return
6612 group_is_overloaded(struct lb_env
*env
, struct sg_lb_stats
*sgs
)
6614 if (sgs
->sum_nr_running
<= sgs
->group_weight
)
6617 if ((sgs
->group_capacity
* 100) <
6618 (sgs
->group_util
* env
->sd
->imbalance_pct
))
6625 group_type
group_classify(struct sched_group
*group
,
6626 struct sg_lb_stats
*sgs
)
6628 if (sgs
->group_no_capacity
)
6629 return group_overloaded
;
6631 if (sg_imbalanced(group
))
6632 return group_imbalanced
;
6638 * update_sg_lb_stats - Update sched_group's statistics for load balancing.
6639 * @env: The load balancing environment.
6640 * @group: sched_group whose statistics are to be updated.
6641 * @load_idx: Load index of sched_domain of this_cpu for load calc.
6642 * @local_group: Does group contain this_cpu.
6643 * @sgs: variable to hold the statistics for this group.
6644 * @overload: Indicate more than one runnable task for any CPU.
6646 static inline void update_sg_lb_stats(struct lb_env
*env
,
6647 struct sched_group
*group
, int load_idx
,
6648 int local_group
, struct sg_lb_stats
*sgs
,
6654 memset(sgs
, 0, sizeof(*sgs
));
6656 for_each_cpu_and(i
, sched_group_cpus(group
), env
->cpus
) {
6657 struct rq
*rq
= cpu_rq(i
);
6659 /* Bias balancing toward cpus of our domain */
6661 load
= target_load(i
, load_idx
);
6663 load
= source_load(i
, load_idx
);
6665 sgs
->group_load
+= load
;
6666 sgs
->group_util
+= cpu_util(i
);
6667 sgs
->sum_nr_running
+= rq
->cfs
.h_nr_running
;
6669 nr_running
= rq
->nr_running
;
6673 #ifdef CONFIG_NUMA_BALANCING
6674 sgs
->nr_numa_running
+= rq
->nr_numa_running
;
6675 sgs
->nr_preferred_running
+= rq
->nr_preferred_running
;
6677 sgs
->sum_weighted_load
+= weighted_cpuload(i
);
6679 * No need to call idle_cpu() if nr_running is not 0
6681 if (!nr_running
&& idle_cpu(i
))
6685 /* Adjust by relative CPU capacity of the group */
6686 sgs
->group_capacity
= group
->sgc
->capacity
;
6687 sgs
->avg_load
= (sgs
->group_load
*SCHED_CAPACITY_SCALE
) / sgs
->group_capacity
;
6689 if (sgs
->sum_nr_running
)
6690 sgs
->load_per_task
= sgs
->sum_weighted_load
/ sgs
->sum_nr_running
;
6692 sgs
->group_weight
= group
->group_weight
;
6694 sgs
->group_no_capacity
= group_is_overloaded(env
, sgs
);
6695 sgs
->group_type
= group_classify(group
, sgs
);
6699 * update_sd_pick_busiest - return 1 on busiest group
6700 * @env: The load balancing environment.
6701 * @sds: sched_domain statistics
6702 * @sg: sched_group candidate to be checked for being the busiest
6703 * @sgs: sched_group statistics
6705 * Determine if @sg is a busier group than the previously selected
6708 * Return: %true if @sg is a busier group than the previously selected
6709 * busiest group. %false otherwise.
6711 static bool update_sd_pick_busiest(struct lb_env
*env
,
6712 struct sd_lb_stats
*sds
,
6713 struct sched_group
*sg
,
6714 struct sg_lb_stats
*sgs
)
6716 struct sg_lb_stats
*busiest
= &sds
->busiest_stat
;
6718 if (sgs
->group_type
> busiest
->group_type
)
6721 if (sgs
->group_type
< busiest
->group_type
)
6724 if (sgs
->avg_load
<= busiest
->avg_load
)
6727 /* This is the busiest node in its class. */
6728 if (!(env
->sd
->flags
& SD_ASYM_PACKING
))
6731 /* No ASYM_PACKING if target cpu is already busy */
6732 if (env
->idle
== CPU_NOT_IDLE
)
6735 * ASYM_PACKING needs to move all the work to the lowest
6736 * numbered CPUs in the group, therefore mark all groups
6737 * higher than ourself as busy.
6739 if (sgs
->sum_nr_running
&& env
->dst_cpu
< group_first_cpu(sg
)) {
6743 /* Prefer to move from highest possible cpu's work */
6744 if (group_first_cpu(sds
->busiest
) < group_first_cpu(sg
))
6751 #ifdef CONFIG_NUMA_BALANCING
6752 static inline enum fbq_type
fbq_classify_group(struct sg_lb_stats
*sgs
)
6754 if (sgs
->sum_nr_running
> sgs
->nr_numa_running
)
6756 if (sgs
->sum_nr_running
> sgs
->nr_preferred_running
)
6761 static inline enum fbq_type
fbq_classify_rq(struct rq
*rq
)
6763 if (rq
->nr_running
> rq
->nr_numa_running
)
6765 if (rq
->nr_running
> rq
->nr_preferred_running
)
6770 static inline enum fbq_type
fbq_classify_group(struct sg_lb_stats
*sgs
)
6775 static inline enum fbq_type
fbq_classify_rq(struct rq
*rq
)
6779 #endif /* CONFIG_NUMA_BALANCING */
6782 * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
6783 * @env: The load balancing environment.
6784 * @sds: variable to hold the statistics for this sched_domain.
6786 static inline void update_sd_lb_stats(struct lb_env
*env
, struct sd_lb_stats
*sds
)
6788 struct sched_domain
*child
= env
->sd
->child
;
6789 struct sched_group
*sg
= env
->sd
->groups
;
6790 struct sg_lb_stats tmp_sgs
;
6791 int load_idx
, prefer_sibling
= 0;
6792 bool overload
= false;
6794 if (child
&& child
->flags
& SD_PREFER_SIBLING
)
6797 load_idx
= get_sd_load_idx(env
->sd
, env
->idle
);
6800 struct sg_lb_stats
*sgs
= &tmp_sgs
;
6803 local_group
= cpumask_test_cpu(env
->dst_cpu
, sched_group_cpus(sg
));
6806 sgs
= &sds
->local_stat
;
6808 if (env
->idle
!= CPU_NEWLY_IDLE
||
6809 time_after_eq(jiffies
, sg
->sgc
->next_update
))
6810 update_group_capacity(env
->sd
, env
->dst_cpu
);
6813 update_sg_lb_stats(env
, sg
, load_idx
, local_group
, sgs
,
6820 * In case the child domain prefers tasks go to siblings
6821 * first, lower the sg capacity so that we'll try
6822 * and move all the excess tasks away. We lower the capacity
6823 * of a group only if the local group has the capacity to fit
6824 * these excess tasks. The extra check prevents the case where
6825 * you always pull from the heaviest group when it is already
6826 * under-utilized (possible with a large weight task outweighs
6827 * the tasks on the system).
6829 if (prefer_sibling
&& sds
->local
&&
6830 group_has_capacity(env
, &sds
->local_stat
) &&
6831 (sgs
->sum_nr_running
> 1)) {
6832 sgs
->group_no_capacity
= 1;
6833 sgs
->group_type
= group_classify(sg
, sgs
);
6836 if (update_sd_pick_busiest(env
, sds
, sg
, sgs
)) {
6838 sds
->busiest_stat
= *sgs
;
6842 /* Now, start updating sd_lb_stats */
6843 sds
->total_load
+= sgs
->group_load
;
6844 sds
->total_capacity
+= sgs
->group_capacity
;
6847 } while (sg
!= env
->sd
->groups
);
6849 if (env
->sd
->flags
& SD_NUMA
)
6850 env
->fbq_type
= fbq_classify_group(&sds
->busiest_stat
);
6852 if (!env
->sd
->parent
) {
6853 /* update overload indicator if we are at root domain */
6854 if (env
->dst_rq
->rd
->overload
!= overload
)
6855 env
->dst_rq
->rd
->overload
= overload
;
6861 * check_asym_packing - Check to see if the group is packed into the
6864 * This is primarily intended to used at the sibling level. Some
6865 * cores like POWER7 prefer to use lower numbered SMT threads. In the
6866 * case of POWER7, it can move to lower SMT modes only when higher
6867 * threads are idle. When in lower SMT modes, the threads will
6868 * perform better since they share less core resources. Hence when we
6869 * have idle threads, we want them to be the higher ones.
6871 * This packing function is run on idle threads. It checks to see if
6872 * the busiest CPU in this domain (core in the P7 case) has a higher
6873 * CPU number than the packing function is being run on. Here we are
6874 * assuming lower CPU number will be equivalent to lower a SMT thread
6877 * Return: 1 when packing is required and a task should be moved to
6878 * this CPU. The amount of the imbalance is returned in *imbalance.
6880 * @env: The load balancing environment.
6881 * @sds: Statistics of the sched_domain which is to be packed
6883 static int check_asym_packing(struct lb_env
*env
, struct sd_lb_stats
*sds
)
6887 if (!(env
->sd
->flags
& SD_ASYM_PACKING
))
6890 if (env
->idle
== CPU_NOT_IDLE
)
6896 busiest_cpu
= group_first_cpu(sds
->busiest
);
6897 if (env
->dst_cpu
> busiest_cpu
)
6900 env
->imbalance
= DIV_ROUND_CLOSEST(
6901 sds
->busiest_stat
.avg_load
* sds
->busiest_stat
.group_capacity
,
6902 SCHED_CAPACITY_SCALE
);
6908 * fix_small_imbalance - Calculate the minor imbalance that exists
6909 * amongst the groups of a sched_domain, during
6911 * @env: The load balancing environment.
6912 * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
6915 void fix_small_imbalance(struct lb_env
*env
, struct sd_lb_stats
*sds
)
6917 unsigned long tmp
, capa_now
= 0, capa_move
= 0;
6918 unsigned int imbn
= 2;
6919 unsigned long scaled_busy_load_per_task
;
6920 struct sg_lb_stats
*local
, *busiest
;
6922 local
= &sds
->local_stat
;
6923 busiest
= &sds
->busiest_stat
;
6925 if (!local
->sum_nr_running
)
6926 local
->load_per_task
= cpu_avg_load_per_task(env
->dst_cpu
);
6927 else if (busiest
->load_per_task
> local
->load_per_task
)
6930 scaled_busy_load_per_task
=
6931 (busiest
->load_per_task
* SCHED_CAPACITY_SCALE
) /
6932 busiest
->group_capacity
;
6934 if (busiest
->avg_load
+ scaled_busy_load_per_task
>=
6935 local
->avg_load
+ (scaled_busy_load_per_task
* imbn
)) {
6936 env
->imbalance
= busiest
->load_per_task
;
6941 * OK, we don't have enough imbalance to justify moving tasks,
6942 * however we may be able to increase total CPU capacity used by
6946 capa_now
+= busiest
->group_capacity
*
6947 min(busiest
->load_per_task
, busiest
->avg_load
);
6948 capa_now
+= local
->group_capacity
*
6949 min(local
->load_per_task
, local
->avg_load
);
6950 capa_now
/= SCHED_CAPACITY_SCALE
;
6952 /* Amount of load we'd subtract */
6953 if (busiest
->avg_load
> scaled_busy_load_per_task
) {
6954 capa_move
+= busiest
->group_capacity
*
6955 min(busiest
->load_per_task
,
6956 busiest
->avg_load
- scaled_busy_load_per_task
);
6959 /* Amount of load we'd add */
6960 if (busiest
->avg_load
* busiest
->group_capacity
<
6961 busiest
->load_per_task
* SCHED_CAPACITY_SCALE
) {
6962 tmp
= (busiest
->avg_load
* busiest
->group_capacity
) /
6963 local
->group_capacity
;
6965 tmp
= (busiest
->load_per_task
* SCHED_CAPACITY_SCALE
) /
6966 local
->group_capacity
;
6968 capa_move
+= local
->group_capacity
*
6969 min(local
->load_per_task
, local
->avg_load
+ tmp
);
6970 capa_move
/= SCHED_CAPACITY_SCALE
;
6972 /* Move if we gain throughput */
6973 if (capa_move
> capa_now
)
6974 env
->imbalance
= busiest
->load_per_task
;
6978 * calculate_imbalance - Calculate the amount of imbalance present within the
6979 * groups of a given sched_domain during load balance.
6980 * @env: load balance environment
6981 * @sds: statistics of the sched_domain whose imbalance is to be calculated.
6983 static inline void calculate_imbalance(struct lb_env
*env
, struct sd_lb_stats
*sds
)
6985 unsigned long max_pull
, load_above_capacity
= ~0UL;
6986 struct sg_lb_stats
*local
, *busiest
;
6988 local
= &sds
->local_stat
;
6989 busiest
= &sds
->busiest_stat
;
6991 if (busiest
->group_type
== group_imbalanced
) {
6993 * In the group_imb case we cannot rely on group-wide averages
6994 * to ensure cpu-load equilibrium, look at wider averages. XXX
6996 busiest
->load_per_task
=
6997 min(busiest
->load_per_task
, sds
->avg_load
);
7001 * In the presence of smp nice balancing, certain scenarios can have
7002 * max load less than avg load(as we skip the groups at or below
7003 * its cpu_capacity, while calculating max_load..)
7005 if (busiest
->avg_load
<= sds
->avg_load
||
7006 local
->avg_load
>= sds
->avg_load
) {
7008 return fix_small_imbalance(env
, sds
);
7012 * If there aren't any idle cpus, avoid creating some.
7014 if (busiest
->group_type
== group_overloaded
&&
7015 local
->group_type
== group_overloaded
) {
7016 load_above_capacity
= busiest
->sum_nr_running
*
7018 if (load_above_capacity
> busiest
->group_capacity
)
7019 load_above_capacity
-= busiest
->group_capacity
;
7021 load_above_capacity
= ~0UL;
7025 * We're trying to get all the cpus to the average_load, so we don't
7026 * want to push ourselves above the average load, nor do we wish to
7027 * reduce the max loaded cpu below the average load. At the same time,
7028 * we also don't want to reduce the group load below the group capacity
7029 * (so that we can implement power-savings policies etc). Thus we look
7030 * for the minimum possible imbalance.
7032 max_pull
= min(busiest
->avg_load
- sds
->avg_load
, load_above_capacity
);
7034 /* How much load to actually move to equalise the imbalance */
7035 env
->imbalance
= min(
7036 max_pull
* busiest
->group_capacity
,
7037 (sds
->avg_load
- local
->avg_load
) * local
->group_capacity
7038 ) / SCHED_CAPACITY_SCALE
;
7041 * if *imbalance is less than the average load per runnable task
7042 * there is no guarantee that any tasks will be moved so we'll have
7043 * a think about bumping its value to force at least one task to be
7046 if (env
->imbalance
< busiest
->load_per_task
)
7047 return fix_small_imbalance(env
, sds
);
7050 /******* find_busiest_group() helpers end here *********************/
7053 * find_busiest_group - Returns the busiest group within the sched_domain
7054 * if there is an imbalance. If there isn't an imbalance, and
7055 * the user has opted for power-savings, it returns a group whose
7056 * CPUs can be put to idle by rebalancing those tasks elsewhere, if
7057 * such a group exists.
7059 * Also calculates the amount of weighted load which should be moved
7060 * to restore balance.
7062 * @env: The load balancing environment.
7064 * Return: - The busiest group if imbalance exists.
7065 * - If no imbalance and user has opted for power-savings balance,
7066 * return the least loaded group whose CPUs can be
7067 * put to idle by rebalancing its tasks onto our group.
7069 static struct sched_group
*find_busiest_group(struct lb_env
*env
)
7071 struct sg_lb_stats
*local
, *busiest
;
7072 struct sd_lb_stats sds
;
7074 init_sd_lb_stats(&sds
);
7077 * Compute the various statistics relavent for load balancing at
7080 update_sd_lb_stats(env
, &sds
);
7081 local
= &sds
.local_stat
;
7082 busiest
= &sds
.busiest_stat
;
7084 /* ASYM feature bypasses nice load balance check */
7085 if (check_asym_packing(env
, &sds
))
7088 /* There is no busy sibling group to pull tasks from */
7089 if (!sds
.busiest
|| busiest
->sum_nr_running
== 0)
7092 sds
.avg_load
= (SCHED_CAPACITY_SCALE
* sds
.total_load
)
7093 / sds
.total_capacity
;
7096 * If the busiest group is imbalanced the below checks don't
7097 * work because they assume all things are equal, which typically
7098 * isn't true due to cpus_allowed constraints and the like.
7100 if (busiest
->group_type
== group_imbalanced
)
7103 /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
7104 if (env
->idle
== CPU_NEWLY_IDLE
&& group_has_capacity(env
, local
) &&
7105 busiest
->group_no_capacity
)
7109 * If the local group is busier than the selected busiest group
7110 * don't try and pull any tasks.
7112 if (local
->avg_load
>= busiest
->avg_load
)
7116 * Don't pull any tasks if this group is already above the domain
7119 if (local
->avg_load
>= sds
.avg_load
)
7122 if (env
->idle
== CPU_IDLE
) {
7124 * This cpu is idle. If the busiest group is not overloaded
7125 * and there is no imbalance between this and busiest group
7126 * wrt idle cpus, it is balanced. The imbalance becomes
7127 * significant if the diff is greater than 1 otherwise we
7128 * might end up to just move the imbalance on another group
7130 if ((busiest
->group_type
!= group_overloaded
) &&
7131 (local
->idle_cpus
<= (busiest
->idle_cpus
+ 1)))
7135 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
7136 * imbalance_pct to be conservative.
7138 if (100 * busiest
->avg_load
<=
7139 env
->sd
->imbalance_pct
* local
->avg_load
)
7144 /* Looks like there is an imbalance. Compute it */
7145 calculate_imbalance(env
, &sds
);
7154 * find_busiest_queue - find the busiest runqueue among the cpus in group.
7156 static struct rq
*find_busiest_queue(struct lb_env
*env
,
7157 struct sched_group
*group
)
7159 struct rq
*busiest
= NULL
, *rq
;
7160 unsigned long busiest_load
= 0, busiest_capacity
= 1;
7163 for_each_cpu_and(i
, sched_group_cpus(group
), env
->cpus
) {
7164 unsigned long capacity
, wl
;
7168 rt
= fbq_classify_rq(rq
);
7171 * We classify groups/runqueues into three groups:
7172 * - regular: there are !numa tasks
7173 * - remote: there are numa tasks that run on the 'wrong' node
7174 * - all: there is no distinction
7176 * In order to avoid migrating ideally placed numa tasks,
7177 * ignore those when there's better options.
7179 * If we ignore the actual busiest queue to migrate another
7180 * task, the next balance pass can still reduce the busiest
7181 * queue by moving tasks around inside the node.
7183 * If we cannot move enough load due to this classification
7184 * the next pass will adjust the group classification and
7185 * allow migration of more tasks.
7187 * Both cases only affect the total convergence complexity.
7189 if (rt
> env
->fbq_type
)
7192 capacity
= capacity_of(i
);
7194 wl
= weighted_cpuload(i
);
7197 * When comparing with imbalance, use weighted_cpuload()
7198 * which is not scaled with the cpu capacity.
7201 if (rq
->nr_running
== 1 && wl
> env
->imbalance
&&
7202 !check_cpu_capacity(rq
, env
->sd
))
7206 * For the load comparisons with the other cpu's, consider
7207 * the weighted_cpuload() scaled with the cpu capacity, so
7208 * that the load can be moved away from the cpu that is
7209 * potentially running at a lower capacity.
7211 * Thus we're looking for max(wl_i / capacity_i), crosswise
7212 * multiplication to rid ourselves of the division works out
7213 * to: wl_i * capacity_j > wl_j * capacity_i; where j is
7214 * our previous maximum.
7216 if (wl
* busiest_capacity
> busiest_load
* capacity
) {
7218 busiest_capacity
= capacity
;
7227 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
7228 * so long as it is large enough.
7230 #define MAX_PINNED_INTERVAL 512
7232 /* Working cpumask for load_balance and load_balance_newidle. */
7233 DEFINE_PER_CPU(cpumask_var_t
, load_balance_mask
);
7235 static int need_active_balance(struct lb_env
*env
)
7237 struct sched_domain
*sd
= env
->sd
;
7239 if (env
->idle
== CPU_NEWLY_IDLE
) {
7242 * ASYM_PACKING needs to force migrate tasks from busy but
7243 * higher numbered CPUs in order to pack all tasks in the
7244 * lowest numbered CPUs.
7246 if ((sd
->flags
& SD_ASYM_PACKING
) && env
->src_cpu
> env
->dst_cpu
)
7251 * The dst_cpu is idle and the src_cpu CPU has only 1 CFS task.
7252 * It's worth migrating the task if the src_cpu's capacity is reduced
7253 * because of other sched_class or IRQs if more capacity stays
7254 * available on dst_cpu.
7256 if ((env
->idle
!= CPU_NOT_IDLE
) &&
7257 (env
->src_rq
->cfs
.h_nr_running
== 1)) {
7258 if ((check_cpu_capacity(env
->src_rq
, sd
)) &&
7259 (capacity_of(env
->src_cpu
)*sd
->imbalance_pct
< capacity_of(env
->dst_cpu
)*100))
7263 return unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2);
7266 static int active_load_balance_cpu_stop(void *data
);
7268 static int should_we_balance(struct lb_env
*env
)
7270 struct sched_group
*sg
= env
->sd
->groups
;
7271 struct cpumask
*sg_cpus
, *sg_mask
;
7272 int cpu
, balance_cpu
= -1;
7275 * In the newly idle case, we will allow all the cpu's
7276 * to do the newly idle load balance.
7278 if (env
->idle
== CPU_NEWLY_IDLE
)
7281 sg_cpus
= sched_group_cpus(sg
);
7282 sg_mask
= sched_group_mask(sg
);
7283 /* Try to find first idle cpu */
7284 for_each_cpu_and(cpu
, sg_cpus
, env
->cpus
) {
7285 if (!cpumask_test_cpu(cpu
, sg_mask
) || !idle_cpu(cpu
))
7292 if (balance_cpu
== -1)
7293 balance_cpu
= group_balance_cpu(sg
);
7296 * First idle cpu or the first cpu(busiest) in this sched group
7297 * is eligible for doing load balancing at this and above domains.
7299 return balance_cpu
== env
->dst_cpu
;
7303 * Check this_cpu to ensure it is balanced within domain. Attempt to move
7304 * tasks if there is an imbalance.
7306 static int load_balance(int this_cpu
, struct rq
*this_rq
,
7307 struct sched_domain
*sd
, enum cpu_idle_type idle
,
7308 int *continue_balancing
)
7310 int ld_moved
, cur_ld_moved
, active_balance
= 0;
7311 struct sched_domain
*sd_parent
= sd
->parent
;
7312 struct sched_group
*group
;
7314 unsigned long flags
;
7315 struct cpumask
*cpus
= this_cpu_cpumask_var_ptr(load_balance_mask
);
7317 struct lb_env env
= {
7319 .dst_cpu
= this_cpu
,
7321 .dst_grpmask
= sched_group_cpus(sd
->groups
),
7323 .loop_break
= sched_nr_migrate_break
,
7326 .tasks
= LIST_HEAD_INIT(env
.tasks
),
7330 * For NEWLY_IDLE load_balancing, we don't need to consider
7331 * other cpus in our group
7333 if (idle
== CPU_NEWLY_IDLE
)
7334 env
.dst_grpmask
= NULL
;
7336 cpumask_copy(cpus
, cpu_active_mask
);
7338 schedstat_inc(sd
, lb_count
[idle
]);
7341 if (!should_we_balance(&env
)) {
7342 *continue_balancing
= 0;
7346 group
= find_busiest_group(&env
);
7348 schedstat_inc(sd
, lb_nobusyg
[idle
]);
7352 busiest
= find_busiest_queue(&env
, group
);
7354 schedstat_inc(sd
, lb_nobusyq
[idle
]);
7358 BUG_ON(busiest
== env
.dst_rq
);
7360 schedstat_add(sd
, lb_imbalance
[idle
], env
.imbalance
);
7362 env
.src_cpu
= busiest
->cpu
;
7363 env
.src_rq
= busiest
;
7366 if (busiest
->nr_running
> 1) {
7368 * Attempt to move tasks. If find_busiest_group has found
7369 * an imbalance but busiest->nr_running <= 1, the group is
7370 * still unbalanced. ld_moved simply stays zero, so it is
7371 * correctly treated as an imbalance.
7373 env
.flags
|= LBF_ALL_PINNED
;
7374 env
.loop_max
= min(sysctl_sched_nr_migrate
, busiest
->nr_running
);
7377 raw_spin_lock_irqsave(&busiest
->lock
, flags
);
7380 * cur_ld_moved - load moved in current iteration
7381 * ld_moved - cumulative load moved across iterations
7383 cur_ld_moved
= detach_tasks(&env
);
7386 * We've detached some tasks from busiest_rq. Every
7387 * task is masked "TASK_ON_RQ_MIGRATING", so we can safely
7388 * unlock busiest->lock, and we are able to be sure
7389 * that nobody can manipulate the tasks in parallel.
7390 * See task_rq_lock() family for the details.
7393 raw_spin_unlock(&busiest
->lock
);
7397 ld_moved
+= cur_ld_moved
;
7400 local_irq_restore(flags
);
7402 if (env
.flags
& LBF_NEED_BREAK
) {
7403 env
.flags
&= ~LBF_NEED_BREAK
;
7408 * Revisit (affine) tasks on src_cpu that couldn't be moved to
7409 * us and move them to an alternate dst_cpu in our sched_group
7410 * where they can run. The upper limit on how many times we
7411 * iterate on same src_cpu is dependent on number of cpus in our
7414 * This changes load balance semantics a bit on who can move
7415 * load to a given_cpu. In addition to the given_cpu itself
7416 * (or a ilb_cpu acting on its behalf where given_cpu is
7417 * nohz-idle), we now have balance_cpu in a position to move
7418 * load to given_cpu. In rare situations, this may cause
7419 * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
7420 * _independently_ and at _same_ time to move some load to
7421 * given_cpu) causing exceess load to be moved to given_cpu.
7422 * This however should not happen so much in practice and
7423 * moreover subsequent load balance cycles should correct the
7424 * excess load moved.
7426 if ((env
.flags
& LBF_DST_PINNED
) && env
.imbalance
> 0) {
7428 /* Prevent to re-select dst_cpu via env's cpus */
7429 cpumask_clear_cpu(env
.dst_cpu
, env
.cpus
);
7431 env
.dst_rq
= cpu_rq(env
.new_dst_cpu
);
7432 env
.dst_cpu
= env
.new_dst_cpu
;
7433 env
.flags
&= ~LBF_DST_PINNED
;
7435 env
.loop_break
= sched_nr_migrate_break
;
7438 * Go back to "more_balance" rather than "redo" since we
7439 * need to continue with same src_cpu.
7445 * We failed to reach balance because of affinity.
7448 int *group_imbalance
= &sd_parent
->groups
->sgc
->imbalance
;
7450 if ((env
.flags
& LBF_SOME_PINNED
) && env
.imbalance
> 0)
7451 *group_imbalance
= 1;
7454 /* All tasks on this runqueue were pinned by CPU affinity */
7455 if (unlikely(env
.flags
& LBF_ALL_PINNED
)) {
7456 cpumask_clear_cpu(cpu_of(busiest
), cpus
);
7457 if (!cpumask_empty(cpus
)) {
7459 env
.loop_break
= sched_nr_migrate_break
;
7462 goto out_all_pinned
;
7467 schedstat_inc(sd
, lb_failed
[idle
]);
7469 * Increment the failure counter only on periodic balance.
7470 * We do not want newidle balance, which can be very
7471 * frequent, pollute the failure counter causing
7472 * excessive cache_hot migrations and active balances.
7474 if (idle
!= CPU_NEWLY_IDLE
)
7475 sd
->nr_balance_failed
++;
7477 if (need_active_balance(&env
)) {
7478 raw_spin_lock_irqsave(&busiest
->lock
, flags
);
7480 /* don't kick the active_load_balance_cpu_stop,
7481 * if the curr task on busiest cpu can't be
7484 if (!cpumask_test_cpu(this_cpu
,
7485 tsk_cpus_allowed(busiest
->curr
))) {
7486 raw_spin_unlock_irqrestore(&busiest
->lock
,
7488 env
.flags
|= LBF_ALL_PINNED
;
7489 goto out_one_pinned
;
7493 * ->active_balance synchronizes accesses to
7494 * ->active_balance_work. Once set, it's cleared
7495 * only after active load balance is finished.
7497 if (!busiest
->active_balance
) {
7498 busiest
->active_balance
= 1;
7499 busiest
->push_cpu
= this_cpu
;
7502 raw_spin_unlock_irqrestore(&busiest
->lock
, flags
);
7504 if (active_balance
) {
7505 stop_one_cpu_nowait(cpu_of(busiest
),
7506 active_load_balance_cpu_stop
, busiest
,
7507 &busiest
->active_balance_work
);
7510 /* We've kicked active balancing, force task migration. */
7511 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
7514 sd
->nr_balance_failed
= 0;
7516 if (likely(!active_balance
)) {
7517 /* We were unbalanced, so reset the balancing interval */
7518 sd
->balance_interval
= sd
->min_interval
;
7521 * If we've begun active balancing, start to back off. This
7522 * case may not be covered by the all_pinned logic if there
7523 * is only 1 task on the busy runqueue (because we don't call
7526 if (sd
->balance_interval
< sd
->max_interval
)
7527 sd
->balance_interval
*= 2;
7534 * We reach balance although we may have faced some affinity
7535 * constraints. Clear the imbalance flag if it was set.
7538 int *group_imbalance
= &sd_parent
->groups
->sgc
->imbalance
;
7540 if (*group_imbalance
)
7541 *group_imbalance
= 0;
7546 * We reach balance because all tasks are pinned at this level so
7547 * we can't migrate them. Let the imbalance flag set so parent level
7548 * can try to migrate them.
7550 schedstat_inc(sd
, lb_balanced
[idle
]);
7552 sd
->nr_balance_failed
= 0;
7555 /* tune up the balancing interval */
7556 if (((env
.flags
& LBF_ALL_PINNED
) &&
7557 sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
7558 (sd
->balance_interval
< sd
->max_interval
))
7559 sd
->balance_interval
*= 2;
7566 static inline unsigned long
7567 get_sd_balance_interval(struct sched_domain
*sd
, int cpu_busy
)
7569 unsigned long interval
= sd
->balance_interval
;
7572 interval
*= sd
->busy_factor
;
7574 /* scale ms to jiffies */
7575 interval
= msecs_to_jiffies(interval
);
7576 interval
= clamp(interval
, 1UL, max_load_balance_interval
);
7582 update_next_balance(struct sched_domain
*sd
, int cpu_busy
, unsigned long *next_balance
)
7584 unsigned long interval
, next
;
7586 interval
= get_sd_balance_interval(sd
, cpu_busy
);
7587 next
= sd
->last_balance
+ interval
;
7589 if (time_after(*next_balance
, next
))
7590 *next_balance
= next
;
7594 * idle_balance is called by schedule() if this_cpu is about to become
7595 * idle. Attempts to pull tasks from other CPUs.
7597 static int idle_balance(struct rq
*this_rq
)
7599 unsigned long next_balance
= jiffies
+ HZ
;
7600 int this_cpu
= this_rq
->cpu
;
7601 struct sched_domain
*sd
;
7602 int pulled_task
= 0;
7606 * We must set idle_stamp _before_ calling idle_balance(), such that we
7607 * measure the duration of idle_balance() as idle time.
7609 this_rq
->idle_stamp
= rq_clock(this_rq
);
7611 if (this_rq
->avg_idle
< sysctl_sched_migration_cost
||
7612 !this_rq
->rd
->overload
) {
7614 sd
= rcu_dereference_check_sched_domain(this_rq
->sd
);
7616 update_next_balance(sd
, 0, &next_balance
);
7622 raw_spin_unlock(&this_rq
->lock
);
7624 update_blocked_averages(this_cpu
);
7626 for_each_domain(this_cpu
, sd
) {
7627 int continue_balancing
= 1;
7628 u64 t0
, domain_cost
;
7630 if (!(sd
->flags
& SD_LOAD_BALANCE
))
7633 if (this_rq
->avg_idle
< curr_cost
+ sd
->max_newidle_lb_cost
) {
7634 update_next_balance(sd
, 0, &next_balance
);
7638 if (sd
->flags
& SD_BALANCE_NEWIDLE
) {
7639 t0
= sched_clock_cpu(this_cpu
);
7641 pulled_task
= load_balance(this_cpu
, this_rq
,
7643 &continue_balancing
);
7645 domain_cost
= sched_clock_cpu(this_cpu
) - t0
;
7646 if (domain_cost
> sd
->max_newidle_lb_cost
)
7647 sd
->max_newidle_lb_cost
= domain_cost
;
7649 curr_cost
+= domain_cost
;
7652 update_next_balance(sd
, 0, &next_balance
);
7655 * Stop searching for tasks to pull if there are
7656 * now runnable tasks on this rq.
7658 if (pulled_task
|| this_rq
->nr_running
> 0)
7663 raw_spin_lock(&this_rq
->lock
);
7665 if (curr_cost
> this_rq
->max_idle_balance_cost
)
7666 this_rq
->max_idle_balance_cost
= curr_cost
;
7669 * While browsing the domains, we released the rq lock, a task could
7670 * have been enqueued in the meantime. Since we're not going idle,
7671 * pretend we pulled a task.
7673 if (this_rq
->cfs
.h_nr_running
&& !pulled_task
)
7677 /* Move the next balance forward */
7678 if (time_after(this_rq
->next_balance
, next_balance
))
7679 this_rq
->next_balance
= next_balance
;
7681 /* Is there a task of a high priority class? */
7682 if (this_rq
->nr_running
!= this_rq
->cfs
.h_nr_running
)
7686 this_rq
->idle_stamp
= 0;
7692 * active_load_balance_cpu_stop is run by cpu stopper. It pushes
7693 * running tasks off the busiest CPU onto idle CPUs. It requires at
7694 * least 1 task to be running on each physical CPU where possible, and
7695 * avoids physical / logical imbalances.
7697 static int active_load_balance_cpu_stop(void *data
)
7699 struct rq
*busiest_rq
= data
;
7700 int busiest_cpu
= cpu_of(busiest_rq
);
7701 int target_cpu
= busiest_rq
->push_cpu
;
7702 struct rq
*target_rq
= cpu_rq(target_cpu
);
7703 struct sched_domain
*sd
;
7704 struct task_struct
*p
= NULL
;
7706 raw_spin_lock_irq(&busiest_rq
->lock
);
7708 /* make sure the requested cpu hasn't gone down in the meantime */
7709 if (unlikely(busiest_cpu
!= smp_processor_id() ||
7710 !busiest_rq
->active_balance
))
7713 /* Is there any task to move? */
7714 if (busiest_rq
->nr_running
<= 1)
7718 * This condition is "impossible", if it occurs
7719 * we need to fix it. Originally reported by
7720 * Bjorn Helgaas on a 128-cpu setup.
7722 BUG_ON(busiest_rq
== target_rq
);
7724 /* Search for an sd spanning us and the target CPU. */
7726 for_each_domain(target_cpu
, sd
) {
7727 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
7728 cpumask_test_cpu(busiest_cpu
, sched_domain_span(sd
)))
7733 struct lb_env env
= {
7735 .dst_cpu
= target_cpu
,
7736 .dst_rq
= target_rq
,
7737 .src_cpu
= busiest_rq
->cpu
,
7738 .src_rq
= busiest_rq
,
7742 schedstat_inc(sd
, alb_count
);
7744 p
= detach_one_task(&env
);
7746 schedstat_inc(sd
, alb_pushed
);
7747 /* Active balancing done, reset the failure counter. */
7748 sd
->nr_balance_failed
= 0;
7750 schedstat_inc(sd
, alb_failed
);
7755 busiest_rq
->active_balance
= 0;
7756 raw_spin_unlock(&busiest_rq
->lock
);
7759 attach_one_task(target_rq
, p
);
7766 static inline int on_null_domain(struct rq
*rq
)
7768 return unlikely(!rcu_dereference_sched(rq
->sd
));
7771 #ifdef CONFIG_NO_HZ_COMMON
7773 * idle load balancing details
7774 * - When one of the busy CPUs notice that there may be an idle rebalancing
7775 * needed, they will kick the idle load balancer, which then does idle
7776 * load balancing for all the idle CPUs.
7779 cpumask_var_t idle_cpus_mask
;
7781 unsigned long next_balance
; /* in jiffy units */
7782 } nohz ____cacheline_aligned
;
7784 static inline int find_new_ilb(void)
7786 int ilb
= cpumask_first(nohz
.idle_cpus_mask
);
7788 if (ilb
< nr_cpu_ids
&& idle_cpu(ilb
))
7795 * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
7796 * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
7797 * CPU (if there is one).
7799 static void nohz_balancer_kick(void)
7803 nohz
.next_balance
++;
7805 ilb_cpu
= find_new_ilb();
7807 if (ilb_cpu
>= nr_cpu_ids
)
7810 if (test_and_set_bit(NOHZ_BALANCE_KICK
, nohz_flags(ilb_cpu
)))
7813 * Use smp_send_reschedule() instead of resched_cpu().
7814 * This way we generate a sched IPI on the target cpu which
7815 * is idle. And the softirq performing nohz idle load balance
7816 * will be run before returning from the IPI.
7818 smp_send_reschedule(ilb_cpu
);
7822 static inline void nohz_balance_exit_idle(int cpu
)
7824 if (unlikely(test_bit(NOHZ_TICK_STOPPED
, nohz_flags(cpu
)))) {
7826 * Completely isolated CPUs don't ever set, so we must test.
7828 if (likely(cpumask_test_cpu(cpu
, nohz
.idle_cpus_mask
))) {
7829 cpumask_clear_cpu(cpu
, nohz
.idle_cpus_mask
);
7830 atomic_dec(&nohz
.nr_cpus
);
7832 clear_bit(NOHZ_TICK_STOPPED
, nohz_flags(cpu
));
7836 static inline void set_cpu_sd_state_busy(void)
7838 struct sched_domain
*sd
;
7839 int cpu
= smp_processor_id();
7842 sd
= rcu_dereference(per_cpu(sd_busy
, cpu
));
7844 if (!sd
|| !sd
->nohz_idle
)
7848 atomic_inc(&sd
->groups
->sgc
->nr_busy_cpus
);
7853 void set_cpu_sd_state_idle(void)
7855 struct sched_domain
*sd
;
7856 int cpu
= smp_processor_id();
7859 sd
= rcu_dereference(per_cpu(sd_busy
, cpu
));
7861 if (!sd
|| sd
->nohz_idle
)
7865 atomic_dec(&sd
->groups
->sgc
->nr_busy_cpus
);
7871 * This routine will record that the cpu is going idle with tick stopped.
7872 * This info will be used in performing idle load balancing in the future.
7874 void nohz_balance_enter_idle(int cpu
)
7877 * If this cpu is going down, then nothing needs to be done.
7879 if (!cpu_active(cpu
))
7882 if (test_bit(NOHZ_TICK_STOPPED
, nohz_flags(cpu
)))
7886 * If we're a completely isolated CPU, we don't play.
7888 if (on_null_domain(cpu_rq(cpu
)))
7891 cpumask_set_cpu(cpu
, nohz
.idle_cpus_mask
);
7892 atomic_inc(&nohz
.nr_cpus
);
7893 set_bit(NOHZ_TICK_STOPPED
, nohz_flags(cpu
));
7896 static int sched_ilb_notifier(struct notifier_block
*nfb
,
7897 unsigned long action
, void *hcpu
)
7899 switch (action
& ~CPU_TASKS_FROZEN
) {
7901 nohz_balance_exit_idle(smp_processor_id());
7909 static DEFINE_SPINLOCK(balancing
);
7912 * Scale the max load_balance interval with the number of CPUs in the system.
7913 * This trades load-balance latency on larger machines for less cross talk.
7915 void update_max_interval(void)
7917 max_load_balance_interval
= HZ
*num_online_cpus()/10;
7921 * It checks each scheduling domain to see if it is due to be balanced,
7922 * and initiates a balancing operation if so.
7924 * Balancing parameters are set up in init_sched_domains.
7926 static void rebalance_domains(struct rq
*rq
, enum cpu_idle_type idle
)
7928 int continue_balancing
= 1;
7930 unsigned long interval
;
7931 struct sched_domain
*sd
;
7932 /* Earliest time when we have to do rebalance again */
7933 unsigned long next_balance
= jiffies
+ 60*HZ
;
7934 int update_next_balance
= 0;
7935 int need_serialize
, need_decay
= 0;
7938 update_blocked_averages(cpu
);
7941 for_each_domain(cpu
, sd
) {
7943 * Decay the newidle max times here because this is a regular
7944 * visit to all the domains. Decay ~1% per second.
7946 if (time_after(jiffies
, sd
->next_decay_max_lb_cost
)) {
7947 sd
->max_newidle_lb_cost
=
7948 (sd
->max_newidle_lb_cost
* 253) / 256;
7949 sd
->next_decay_max_lb_cost
= jiffies
+ HZ
;
7952 max_cost
+= sd
->max_newidle_lb_cost
;
7954 if (!(sd
->flags
& SD_LOAD_BALANCE
))
7958 * Stop the load balance at this level. There is another
7959 * CPU in our sched group which is doing load balancing more
7962 if (!continue_balancing
) {
7968 interval
= get_sd_balance_interval(sd
, idle
!= CPU_IDLE
);
7970 need_serialize
= sd
->flags
& SD_SERIALIZE
;
7971 if (need_serialize
) {
7972 if (!spin_trylock(&balancing
))
7976 if (time_after_eq(jiffies
, sd
->last_balance
+ interval
)) {
7977 if (load_balance(cpu
, rq
, sd
, idle
, &continue_balancing
)) {
7979 * The LBF_DST_PINNED logic could have changed
7980 * env->dst_cpu, so we can't know our idle
7981 * state even if we migrated tasks. Update it.
7983 idle
= idle_cpu(cpu
) ? CPU_IDLE
: CPU_NOT_IDLE
;
7985 sd
->last_balance
= jiffies
;
7986 interval
= get_sd_balance_interval(sd
, idle
!= CPU_IDLE
);
7989 spin_unlock(&balancing
);
7991 if (time_after(next_balance
, sd
->last_balance
+ interval
)) {
7992 next_balance
= sd
->last_balance
+ interval
;
7993 update_next_balance
= 1;
7998 * Ensure the rq-wide value also decays but keep it at a
7999 * reasonable floor to avoid funnies with rq->avg_idle.
8001 rq
->max_idle_balance_cost
=
8002 max((u64
)sysctl_sched_migration_cost
, max_cost
);
8007 * next_balance will be updated only when there is a need.
8008 * When the cpu is attached to null domain for ex, it will not be
8011 if (likely(update_next_balance
)) {
8012 rq
->next_balance
= next_balance
;
8014 #ifdef CONFIG_NO_HZ_COMMON
8016 * If this CPU has been elected to perform the nohz idle
8017 * balance. Other idle CPUs have already rebalanced with
8018 * nohz_idle_balance() and nohz.next_balance has been
8019 * updated accordingly. This CPU is now running the idle load
8020 * balance for itself and we need to update the
8021 * nohz.next_balance accordingly.
8023 if ((idle
== CPU_IDLE
) && time_after(nohz
.next_balance
, rq
->next_balance
))
8024 nohz
.next_balance
= rq
->next_balance
;
8029 #ifdef CONFIG_NO_HZ_COMMON
8031 * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
8032 * rebalancing for all the cpus for whom scheduler ticks are stopped.
8034 static void nohz_idle_balance(struct rq
*this_rq
, enum cpu_idle_type idle
)
8036 int this_cpu
= this_rq
->cpu
;
8039 /* Earliest time when we have to do rebalance again */
8040 unsigned long next_balance
= jiffies
+ 60*HZ
;
8041 int update_next_balance
= 0;
8043 if (idle
!= CPU_IDLE
||
8044 !test_bit(NOHZ_BALANCE_KICK
, nohz_flags(this_cpu
)))
8047 for_each_cpu(balance_cpu
, nohz
.idle_cpus_mask
) {
8048 if (balance_cpu
== this_cpu
|| !idle_cpu(balance_cpu
))
8052 * If this cpu gets work to do, stop the load balancing
8053 * work being done for other cpus. Next load
8054 * balancing owner will pick it up.
8059 rq
= cpu_rq(balance_cpu
);
8062 * If time for next balance is due,
8065 if (time_after_eq(jiffies
, rq
->next_balance
)) {
8066 raw_spin_lock_irq(&rq
->lock
);
8067 update_rq_clock(rq
);
8068 cpu_load_update_idle(rq
);
8069 raw_spin_unlock_irq(&rq
->lock
);
8070 rebalance_domains(rq
, CPU_IDLE
);
8073 if (time_after(next_balance
, rq
->next_balance
)) {
8074 next_balance
= rq
->next_balance
;
8075 update_next_balance
= 1;
8080 * next_balance will be updated only when there is a need.
8081 * When the CPU is attached to null domain for ex, it will not be
8084 if (likely(update_next_balance
))
8085 nohz
.next_balance
= next_balance
;
8087 clear_bit(NOHZ_BALANCE_KICK
, nohz_flags(this_cpu
));
8091 * Current heuristic for kicking the idle load balancer in the presence
8092 * of an idle cpu in the system.
8093 * - This rq has more than one task.
8094 * - This rq has at least one CFS task and the capacity of the CPU is
8095 * significantly reduced because of RT tasks or IRQs.
8096 * - At parent of LLC scheduler domain level, this cpu's scheduler group has
8097 * multiple busy cpu.
8098 * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
8099 * domain span are idle.
8101 static inline bool nohz_kick_needed(struct rq
*rq
)
8103 unsigned long now
= jiffies
;
8104 struct sched_domain
*sd
;
8105 struct sched_group_capacity
*sgc
;
8106 int nr_busy
, cpu
= rq
->cpu
;
8109 if (unlikely(rq
->idle_balance
))
8113 * We may be recently in ticked or tickless idle mode. At the first
8114 * busy tick after returning from idle, we will update the busy stats.
8116 set_cpu_sd_state_busy();
8117 nohz_balance_exit_idle(cpu
);
8120 * None are in tickless mode and hence no need for NOHZ idle load
8123 if (likely(!atomic_read(&nohz
.nr_cpus
)))
8126 if (time_before(now
, nohz
.next_balance
))
8129 if (rq
->nr_running
>= 2)
8133 sd
= rcu_dereference(per_cpu(sd_busy
, cpu
));
8135 sgc
= sd
->groups
->sgc
;
8136 nr_busy
= atomic_read(&sgc
->nr_busy_cpus
);
8145 sd
= rcu_dereference(rq
->sd
);
8147 if ((rq
->cfs
.h_nr_running
>= 1) &&
8148 check_cpu_capacity(rq
, sd
)) {
8154 sd
= rcu_dereference(per_cpu(sd_asym
, cpu
));
8155 if (sd
&& (cpumask_first_and(nohz
.idle_cpus_mask
,
8156 sched_domain_span(sd
)) < cpu
)) {
8166 static void nohz_idle_balance(struct rq
*this_rq
, enum cpu_idle_type idle
) { }
8170 * run_rebalance_domains is triggered when needed from the scheduler tick.
8171 * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
8173 static void run_rebalance_domains(struct softirq_action
*h
)
8175 struct rq
*this_rq
= this_rq();
8176 enum cpu_idle_type idle
= this_rq
->idle_balance
?
8177 CPU_IDLE
: CPU_NOT_IDLE
;
8180 * If this cpu has a pending nohz_balance_kick, then do the
8181 * balancing on behalf of the other idle cpus whose ticks are
8182 * stopped. Do nohz_idle_balance *before* rebalance_domains to
8183 * give the idle cpus a chance to load balance. Else we may
8184 * load balance only within the local sched_domain hierarchy
8185 * and abort nohz_idle_balance altogether if we pull some load.
8187 nohz_idle_balance(this_rq
, idle
);
8188 rebalance_domains(this_rq
, idle
);
8192 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
8194 void trigger_load_balance(struct rq
*rq
)
8196 /* Don't need to rebalance while attached to NULL domain */
8197 if (unlikely(on_null_domain(rq
)))
8200 if (time_after_eq(jiffies
, rq
->next_balance
))
8201 raise_softirq(SCHED_SOFTIRQ
);
8202 #ifdef CONFIG_NO_HZ_COMMON
8203 if (nohz_kick_needed(rq
))
8204 nohz_balancer_kick();
8208 static void rq_online_fair(struct rq
*rq
)
8212 update_runtime_enabled(rq
);
8215 static void rq_offline_fair(struct rq
*rq
)
8219 /* Ensure any throttled groups are reachable by pick_next_task */
8220 unthrottle_offline_cfs_rqs(rq
);
8223 #endif /* CONFIG_SMP */
8226 * scheduler tick hitting a task of our scheduling class:
8228 static void task_tick_fair(struct rq
*rq
, struct task_struct
*curr
, int queued
)
8230 struct cfs_rq
*cfs_rq
;
8231 struct sched_entity
*se
= &curr
->se
;
8233 for_each_sched_entity(se
) {
8234 cfs_rq
= cfs_rq_of(se
);
8235 entity_tick(cfs_rq
, se
, queued
);
8238 if (static_branch_unlikely(&sched_numa_balancing
))
8239 task_tick_numa(rq
, curr
);
8243 * called on fork with the child task as argument from the parent's context
8244 * - child not yet on the tasklist
8245 * - preemption disabled
8247 static void task_fork_fair(struct task_struct
*p
)
8249 struct cfs_rq
*cfs_rq
;
8250 struct sched_entity
*se
= &p
->se
, *curr
;
8251 int this_cpu
= smp_processor_id();
8252 struct rq
*rq
= this_rq();
8253 unsigned long flags
;
8255 raw_spin_lock_irqsave(&rq
->lock
, flags
);
8257 update_rq_clock(rq
);
8259 cfs_rq
= task_cfs_rq(current
);
8260 curr
= cfs_rq
->curr
;
8263 * Not only the cpu but also the task_group of the parent might have
8264 * been changed after parent->se.parent,cfs_rq were copied to
8265 * child->se.parent,cfs_rq. So call __set_task_cpu() to make those
8266 * of child point to valid ones.
8269 __set_task_cpu(p
, this_cpu
);
8272 update_curr(cfs_rq
);
8275 se
->vruntime
= curr
->vruntime
;
8276 place_entity(cfs_rq
, se
, 1);
8278 if (sysctl_sched_child_runs_first
&& curr
&& entity_before(curr
, se
)) {
8280 * Upon rescheduling, sched_class::put_prev_task() will place
8281 * 'current' within the tree based on its new key value.
8283 swap(curr
->vruntime
, se
->vruntime
);
8287 se
->vruntime
-= cfs_rq
->min_vruntime
;
8289 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
8293 * Priority of the task has changed. Check to see if we preempt
8297 prio_changed_fair(struct rq
*rq
, struct task_struct
*p
, int oldprio
)
8299 if (!task_on_rq_queued(p
))
8303 * Reschedule if we are currently running on this runqueue and
8304 * our priority decreased, or if we are not currently running on
8305 * this runqueue and our priority is higher than the current's
8307 if (rq
->curr
== p
) {
8308 if (p
->prio
> oldprio
)
8311 check_preempt_curr(rq
, p
, 0);
8314 static inline bool vruntime_normalized(struct task_struct
*p
)
8316 struct sched_entity
*se
= &p
->se
;
8319 * In both the TASK_ON_RQ_QUEUED and TASK_ON_RQ_MIGRATING cases,
8320 * the dequeue_entity(.flags=0) will already have normalized the
8327 * When !on_rq, vruntime of the task has usually NOT been normalized.
8328 * But there are some cases where it has already been normalized:
8330 * - A forked child which is waiting for being woken up by
8331 * wake_up_new_task().
8332 * - A task which has been woken up by try_to_wake_up() and
8333 * waiting for actually being woken up by sched_ttwu_pending().
8335 if (!se
->sum_exec_runtime
|| p
->state
== TASK_WAKING
)
8341 static void detach_task_cfs_rq(struct task_struct
*p
)
8343 struct sched_entity
*se
= &p
->se
;
8344 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
8346 if (!vruntime_normalized(p
)) {
8348 * Fix up our vruntime so that the current sleep doesn't
8349 * cause 'unlimited' sleep bonus.
8351 place_entity(cfs_rq
, se
, 0);
8352 se
->vruntime
-= cfs_rq
->min_vruntime
;
8355 /* Catch up with the cfs_rq and remove our load when we leave */
8356 detach_entity_load_avg(cfs_rq
, se
);
8359 static void attach_task_cfs_rq(struct task_struct
*p
)
8361 struct sched_entity
*se
= &p
->se
;
8362 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
8364 #ifdef CONFIG_FAIR_GROUP_SCHED
8366 * Since the real-depth could have been changed (only FAIR
8367 * class maintain depth value), reset depth properly.
8369 se
->depth
= se
->parent
? se
->parent
->depth
+ 1 : 0;
8372 /* Synchronize task with its cfs_rq */
8373 attach_entity_load_avg(cfs_rq
, se
);
8375 if (!vruntime_normalized(p
))
8376 se
->vruntime
+= cfs_rq
->min_vruntime
;
8379 static void switched_from_fair(struct rq
*rq
, struct task_struct
*p
)
8381 detach_task_cfs_rq(p
);
8384 static void switched_to_fair(struct rq
*rq
, struct task_struct
*p
)
8386 attach_task_cfs_rq(p
);
8388 if (task_on_rq_queued(p
)) {
8390 * We were most likely switched from sched_rt, so
8391 * kick off the schedule if running, otherwise just see
8392 * if we can still preempt the current task.
8397 check_preempt_curr(rq
, p
, 0);
8401 /* Account for a task changing its policy or group.
8403 * This routine is mostly called to set cfs_rq->curr field when a task
8404 * migrates between groups/classes.
8406 static void set_curr_task_fair(struct rq
*rq
)
8408 struct sched_entity
*se
= &rq
->curr
->se
;
8410 for_each_sched_entity(se
) {
8411 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
8413 set_next_entity(cfs_rq
, se
);
8414 /* ensure bandwidth has been allocated on our new cfs_rq */
8415 account_cfs_rq_runtime(cfs_rq
, 0);
8419 void init_cfs_rq(struct cfs_rq
*cfs_rq
)
8421 cfs_rq
->tasks_timeline
= RB_ROOT
;
8422 cfs_rq
->min_vruntime
= (u64
)(-(1LL << 20));
8423 #ifndef CONFIG_64BIT
8424 cfs_rq
->min_vruntime_copy
= cfs_rq
->min_vruntime
;
8427 atomic_long_set(&cfs_rq
->removed_load_avg
, 0);
8428 atomic_long_set(&cfs_rq
->removed_util_avg
, 0);
8432 #ifdef CONFIG_FAIR_GROUP_SCHED
8433 static void task_move_group_fair(struct task_struct
*p
)
8435 detach_task_cfs_rq(p
);
8436 set_task_rq(p
, task_cpu(p
));
8439 /* Tell se's cfs_rq has been changed -- migrated */
8440 p
->se
.avg
.last_update_time
= 0;
8442 attach_task_cfs_rq(p
);
8445 void free_fair_sched_group(struct task_group
*tg
)
8449 destroy_cfs_bandwidth(tg_cfs_bandwidth(tg
));
8451 for_each_possible_cpu(i
) {
8453 kfree(tg
->cfs_rq
[i
]);
8462 int alloc_fair_sched_group(struct task_group
*tg
, struct task_group
*parent
)
8464 struct cfs_rq
*cfs_rq
;
8465 struct sched_entity
*se
;
8468 tg
->cfs_rq
= kzalloc(sizeof(cfs_rq
) * nr_cpu_ids
, GFP_KERNEL
);
8471 tg
->se
= kzalloc(sizeof(se
) * nr_cpu_ids
, GFP_KERNEL
);
8475 tg
->shares
= NICE_0_LOAD
;
8477 init_cfs_bandwidth(tg_cfs_bandwidth(tg
));
8479 for_each_possible_cpu(i
) {
8480 cfs_rq
= kzalloc_node(sizeof(struct cfs_rq
),
8481 GFP_KERNEL
, cpu_to_node(i
));
8485 se
= kzalloc_node(sizeof(struct sched_entity
),
8486 GFP_KERNEL
, cpu_to_node(i
));
8490 init_cfs_rq(cfs_rq
);
8491 init_tg_cfs_entry(tg
, cfs_rq
, se
, i
, parent
->se
[i
]);
8492 init_entity_runnable_average(se
);
8493 post_init_entity_util_avg(se
);
8504 void unregister_fair_sched_group(struct task_group
*tg
)
8506 unsigned long flags
;
8510 for_each_possible_cpu(cpu
) {
8512 remove_entity_load_avg(tg
->se
[cpu
]);
8515 * Only empty task groups can be destroyed; so we can speculatively
8516 * check on_list without danger of it being re-added.
8518 if (!tg
->cfs_rq
[cpu
]->on_list
)
8523 raw_spin_lock_irqsave(&rq
->lock
, flags
);
8524 list_del_leaf_cfs_rq(tg
->cfs_rq
[cpu
]);
8525 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
8529 void init_tg_cfs_entry(struct task_group
*tg
, struct cfs_rq
*cfs_rq
,
8530 struct sched_entity
*se
, int cpu
,
8531 struct sched_entity
*parent
)
8533 struct rq
*rq
= cpu_rq(cpu
);
8537 init_cfs_rq_runtime(cfs_rq
);
8539 tg
->cfs_rq
[cpu
] = cfs_rq
;
8542 /* se could be NULL for root_task_group */
8547 se
->cfs_rq
= &rq
->cfs
;
8550 se
->cfs_rq
= parent
->my_q
;
8551 se
->depth
= parent
->depth
+ 1;
8555 /* guarantee group entities always have weight */
8556 update_load_set(&se
->load
, NICE_0_LOAD
);
8557 se
->parent
= parent
;
8560 static DEFINE_MUTEX(shares_mutex
);
8562 int sched_group_set_shares(struct task_group
*tg
, unsigned long shares
)
8565 unsigned long flags
;
8568 * We can't change the weight of the root cgroup.
8573 shares
= clamp(shares
, scale_load(MIN_SHARES
), scale_load(MAX_SHARES
));
8575 mutex_lock(&shares_mutex
);
8576 if (tg
->shares
== shares
)
8579 tg
->shares
= shares
;
8580 for_each_possible_cpu(i
) {
8581 struct rq
*rq
= cpu_rq(i
);
8582 struct sched_entity
*se
;
8585 /* Propagate contribution to hierarchy */
8586 raw_spin_lock_irqsave(&rq
->lock
, flags
);
8588 /* Possible calls to update_curr() need rq clock */
8589 update_rq_clock(rq
);
8590 for_each_sched_entity(se
)
8591 update_cfs_shares(group_cfs_rq(se
));
8592 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
8596 mutex_unlock(&shares_mutex
);
8599 #else /* CONFIG_FAIR_GROUP_SCHED */
8601 void free_fair_sched_group(struct task_group
*tg
) { }
8603 int alloc_fair_sched_group(struct task_group
*tg
, struct task_group
*parent
)
8608 void unregister_fair_sched_group(struct task_group
*tg
) { }
8610 #endif /* CONFIG_FAIR_GROUP_SCHED */
8613 static unsigned int get_rr_interval_fair(struct rq
*rq
, struct task_struct
*task
)
8615 struct sched_entity
*se
= &task
->se
;
8616 unsigned int rr_interval
= 0;
8619 * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
8622 if (rq
->cfs
.load
.weight
)
8623 rr_interval
= NS_TO_JIFFIES(sched_slice(cfs_rq_of(se
), se
));
8629 * All the scheduling class methods:
8631 const struct sched_class fair_sched_class
= {
8632 .next
= &idle_sched_class
,
8633 .enqueue_task
= enqueue_task_fair
,
8634 .dequeue_task
= dequeue_task_fair
,
8635 .yield_task
= yield_task_fair
,
8636 .yield_to_task
= yield_to_task_fair
,
8638 .check_preempt_curr
= check_preempt_wakeup
,
8640 .pick_next_task
= pick_next_task_fair
,
8641 .put_prev_task
= put_prev_task_fair
,
8644 .select_task_rq
= select_task_rq_fair
,
8645 .migrate_task_rq
= migrate_task_rq_fair
,
8647 .rq_online
= rq_online_fair
,
8648 .rq_offline
= rq_offline_fair
,
8650 .task_waking
= task_waking_fair
,
8651 .task_dead
= task_dead_fair
,
8652 .set_cpus_allowed
= set_cpus_allowed_common
,
8655 .set_curr_task
= set_curr_task_fair
,
8656 .task_tick
= task_tick_fair
,
8657 .task_fork
= task_fork_fair
,
8659 .prio_changed
= prio_changed_fair
,
8660 .switched_from
= switched_from_fair
,
8661 .switched_to
= switched_to_fair
,
8663 .get_rr_interval
= get_rr_interval_fair
,
8665 .update_curr
= update_curr_fair
,
8667 #ifdef CONFIG_FAIR_GROUP_SCHED
8668 .task_move_group
= task_move_group_fair
,
8672 #ifdef CONFIG_SCHED_DEBUG
8673 void print_cfs_stats(struct seq_file
*m
, int cpu
)
8675 struct cfs_rq
*cfs_rq
;
8678 for_each_leaf_cfs_rq(cpu_rq(cpu
), cfs_rq
)
8679 print_cfs_rq(m
, cpu
, cfs_rq
);
8683 #ifdef CONFIG_NUMA_BALANCING
8684 void show_numa_stats(struct task_struct
*p
, struct seq_file
*m
)
8687 unsigned long tsf
= 0, tpf
= 0, gsf
= 0, gpf
= 0;
8689 for_each_online_node(node
) {
8690 if (p
->numa_faults
) {
8691 tsf
= p
->numa_faults
[task_faults_idx(NUMA_MEM
, node
, 0)];
8692 tpf
= p
->numa_faults
[task_faults_idx(NUMA_MEM
, node
, 1)];
8694 if (p
->numa_group
) {
8695 gsf
= p
->numa_group
->faults
[task_faults_idx(NUMA_MEM
, node
, 0)],
8696 gpf
= p
->numa_group
->faults
[task_faults_idx(NUMA_MEM
, node
, 1)];
8698 print_numa_stats(m
, node
, tsf
, tpf
, gsf
, gpf
);
8701 #endif /* CONFIG_NUMA_BALANCING */
8702 #endif /* CONFIG_SCHED_DEBUG */
8704 __init
void init_sched_fair_class(void)
8707 open_softirq(SCHED_SOFTIRQ
, run_rebalance_domains
);
8709 #ifdef CONFIG_NO_HZ_COMMON
8710 nohz
.next_balance
= jiffies
;
8711 zalloc_cpumask_var(&nohz
.idle_cpus_mask
, GFP_NOWAIT
);
8712 cpu_notifier(sched_ilb_notifier
, 0);