2 * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH)
4 * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
6 * Interactivity improvements by Mike Galbraith
7 * (C) 2007 Mike Galbraith <efault@gmx.de>
9 * Various enhancements by Dmitry Adamushko.
10 * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com>
12 * Group scheduling enhancements by Srivatsa Vaddagiri
13 * Copyright IBM Corporation, 2007
14 * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
16 * Scaled math optimizations by Thomas Gleixner
17 * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de>
19 * Adaptive scheduling granularity, math enhancements by Peter Zijlstra
20 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
23 #include <linux/latencytop.h>
24 #include <linux/sched.h>
25 #include <linux/cpumask.h>
26 #include <linux/slab.h>
27 #include <linux/profile.h>
28 #include <linux/interrupt.h>
29 #include <linux/mempolicy.h>
30 #include <linux/task_work.h>
32 #include <trace/events/sched.h>
37 * Targeted preemption latency for CPU-bound tasks:
38 * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
40 * NOTE: this latency value is not the same as the concept of
41 * 'timeslice length' - timeslices in CFS are of variable length
42 * and have no persistent notion like in traditional, time-slice
43 * based scheduling concepts.
45 * (to see the precise effective timeslice length of your workload,
46 * run vmstat and monitor the context-switches (cs) field)
48 unsigned int sysctl_sched_latency
= 6000000ULL;
49 unsigned int normalized_sysctl_sched_latency
= 6000000ULL;
52 * The initial- and re-scaling of tunables is configurable
53 * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
56 * SCHED_TUNABLESCALING_NONE - unscaled, always *1
57 * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
58 * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
60 enum sched_tunable_scaling sysctl_sched_tunable_scaling
61 = SCHED_TUNABLESCALING_LOG
;
64 * Minimal preemption granularity for CPU-bound tasks:
65 * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
67 unsigned int sysctl_sched_min_granularity
= 750000ULL;
68 unsigned int normalized_sysctl_sched_min_granularity
= 750000ULL;
71 * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
73 static unsigned int sched_nr_latency
= 8;
76 * After fork, child runs first. If set to 0 (default) then
77 * parent will (try to) run first.
79 unsigned int sysctl_sched_child_runs_first __read_mostly
;
82 * SCHED_OTHER wake-up granularity.
83 * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
85 * This option delays the preemption effects of decoupled workloads
86 * and reduces their over-scheduling. Synchronous workloads will still
87 * have immediate wakeup/sleep latencies.
89 unsigned int sysctl_sched_wakeup_granularity
= 1000000UL;
90 unsigned int normalized_sysctl_sched_wakeup_granularity
= 1000000UL;
92 const_debug
unsigned int sysctl_sched_migration_cost
= 500000UL;
95 * The exponential sliding window over which load is averaged for shares
99 unsigned int __read_mostly sysctl_sched_shares_window
= 10000000UL;
101 #ifdef CONFIG_CFS_BANDWIDTH
103 * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
104 * each time a cfs_rq requests quota.
106 * Note: in the case that the slice exceeds the runtime remaining (either due
107 * to consumption or the quota being specified to be smaller than the slice)
108 * we will always only issue the remaining available time.
110 * default: 5 msec, units: microseconds
112 unsigned int sysctl_sched_cfs_bandwidth_slice
= 5000UL;
116 * Increase the granularity value when there are more CPUs,
117 * because with more CPUs the 'effective latency' as visible
118 * to users decreases. But the relationship is not linear,
119 * so pick a second-best guess by going with the log2 of the
122 * This idea comes from the SD scheduler of Con Kolivas:
124 static int get_update_sysctl_factor(void)
126 unsigned int cpus
= min_t(int, num_online_cpus(), 8);
129 switch (sysctl_sched_tunable_scaling
) {
130 case SCHED_TUNABLESCALING_NONE
:
133 case SCHED_TUNABLESCALING_LINEAR
:
136 case SCHED_TUNABLESCALING_LOG
:
138 factor
= 1 + ilog2(cpus
);
145 static void update_sysctl(void)
147 unsigned int factor
= get_update_sysctl_factor();
149 #define SET_SYSCTL(name) \
150 (sysctl_##name = (factor) * normalized_sysctl_##name)
151 SET_SYSCTL(sched_min_granularity
);
152 SET_SYSCTL(sched_latency
);
153 SET_SYSCTL(sched_wakeup_granularity
);
157 void sched_init_granularity(void)
162 #if BITS_PER_LONG == 32
163 # define WMULT_CONST (~0UL)
165 # define WMULT_CONST (1UL << 32)
168 #define WMULT_SHIFT 32
171 * Shift right and round:
173 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
176 * delta *= weight / lw
179 calc_delta_mine(unsigned long delta_exec
, unsigned long weight
,
180 struct load_weight
*lw
)
185 * weight can be less than 2^SCHED_LOAD_RESOLUTION for task group sched
186 * entities since MIN_SHARES = 2. Treat weight as 1 if less than
187 * 2^SCHED_LOAD_RESOLUTION.
189 if (likely(weight
> (1UL << SCHED_LOAD_RESOLUTION
)))
190 tmp
= (u64
)delta_exec
* scale_load_down(weight
);
192 tmp
= (u64
)delta_exec
;
194 if (!lw
->inv_weight
) {
195 unsigned long w
= scale_load_down(lw
->weight
);
197 if (BITS_PER_LONG
> 32 && unlikely(w
>= WMULT_CONST
))
199 else if (unlikely(!w
))
200 lw
->inv_weight
= WMULT_CONST
;
202 lw
->inv_weight
= WMULT_CONST
/ w
;
206 * Check whether we'd overflow the 64-bit multiplication:
208 if (unlikely(tmp
> WMULT_CONST
))
209 tmp
= SRR(SRR(tmp
, WMULT_SHIFT
/2) * lw
->inv_weight
,
212 tmp
= SRR(tmp
* lw
->inv_weight
, WMULT_SHIFT
);
214 return (unsigned long)min(tmp
, (u64
)(unsigned long)LONG_MAX
);
218 const struct sched_class fair_sched_class
;
220 /**************************************************************
221 * CFS operations on generic schedulable entities:
224 #ifdef CONFIG_FAIR_GROUP_SCHED
226 /* cpu runqueue to which this cfs_rq is attached */
227 static inline struct rq
*rq_of(struct cfs_rq
*cfs_rq
)
232 /* An entity is a task if it doesn't "own" a runqueue */
233 #define entity_is_task(se) (!se->my_q)
235 static inline struct task_struct
*task_of(struct sched_entity
*se
)
237 #ifdef CONFIG_SCHED_DEBUG
238 WARN_ON_ONCE(!entity_is_task(se
));
240 return container_of(se
, struct task_struct
, se
);
243 /* Walk up scheduling entities hierarchy */
244 #define for_each_sched_entity(se) \
245 for (; se; se = se->parent)
247 static inline struct cfs_rq
*task_cfs_rq(struct task_struct
*p
)
252 /* runqueue on which this entity is (to be) queued */
253 static inline struct cfs_rq
*cfs_rq_of(struct sched_entity
*se
)
258 /* runqueue "owned" by this group */
259 static inline struct cfs_rq
*group_cfs_rq(struct sched_entity
*grp
)
264 static inline void list_add_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
266 if (!cfs_rq
->on_list
) {
268 * Ensure we either appear before our parent (if already
269 * enqueued) or force our parent to appear after us when it is
270 * enqueued. The fact that we always enqueue bottom-up
271 * reduces this to two cases.
273 if (cfs_rq
->tg
->parent
&&
274 cfs_rq
->tg
->parent
->cfs_rq
[cpu_of(rq_of(cfs_rq
))]->on_list
) {
275 list_add_rcu(&cfs_rq
->leaf_cfs_rq_list
,
276 &rq_of(cfs_rq
)->leaf_cfs_rq_list
);
278 list_add_tail_rcu(&cfs_rq
->leaf_cfs_rq_list
,
279 &rq_of(cfs_rq
)->leaf_cfs_rq_list
);
286 static inline void list_del_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
288 if (cfs_rq
->on_list
) {
289 list_del_rcu(&cfs_rq
->leaf_cfs_rq_list
);
294 /* Iterate thr' all leaf cfs_rq's on a runqueue */
295 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
296 list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
298 /* Do the two (enqueued) entities belong to the same group ? */
300 is_same_group(struct sched_entity
*se
, struct sched_entity
*pse
)
302 if (se
->cfs_rq
== pse
->cfs_rq
)
308 static inline struct sched_entity
*parent_entity(struct sched_entity
*se
)
313 /* return depth at which a sched entity is present in the hierarchy */
314 static inline int depth_se(struct sched_entity
*se
)
318 for_each_sched_entity(se
)
325 find_matching_se(struct sched_entity
**se
, struct sched_entity
**pse
)
327 int se_depth
, pse_depth
;
330 * preemption test can be made between sibling entities who are in the
331 * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
332 * both tasks until we find their ancestors who are siblings of common
336 /* First walk up until both entities are at same depth */
337 se_depth
= depth_se(*se
);
338 pse_depth
= depth_se(*pse
);
340 while (se_depth
> pse_depth
) {
342 *se
= parent_entity(*se
);
345 while (pse_depth
> se_depth
) {
347 *pse
= parent_entity(*pse
);
350 while (!is_same_group(*se
, *pse
)) {
351 *se
= parent_entity(*se
);
352 *pse
= parent_entity(*pse
);
356 #else /* !CONFIG_FAIR_GROUP_SCHED */
358 static inline struct task_struct
*task_of(struct sched_entity
*se
)
360 return container_of(se
, struct task_struct
, se
);
363 static inline struct rq
*rq_of(struct cfs_rq
*cfs_rq
)
365 return container_of(cfs_rq
, struct rq
, cfs
);
368 #define entity_is_task(se) 1
370 #define for_each_sched_entity(se) \
371 for (; se; se = NULL)
373 static inline struct cfs_rq
*task_cfs_rq(struct task_struct
*p
)
375 return &task_rq(p
)->cfs
;
378 static inline struct cfs_rq
*cfs_rq_of(struct sched_entity
*se
)
380 struct task_struct
*p
= task_of(se
);
381 struct rq
*rq
= task_rq(p
);
386 /* runqueue "owned" by this group */
387 static inline struct cfs_rq
*group_cfs_rq(struct sched_entity
*grp
)
392 static inline void list_add_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
396 static inline void list_del_leaf_cfs_rq(struct cfs_rq
*cfs_rq
)
400 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
401 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
404 is_same_group(struct sched_entity
*se
, struct sched_entity
*pse
)
409 static inline struct sched_entity
*parent_entity(struct sched_entity
*se
)
415 find_matching_se(struct sched_entity
**se
, struct sched_entity
**pse
)
419 #endif /* CONFIG_FAIR_GROUP_SCHED */
421 static __always_inline
422 void account_cfs_rq_runtime(struct cfs_rq
*cfs_rq
, unsigned long delta_exec
);
424 /**************************************************************
425 * Scheduling class tree data structure manipulation methods:
428 static inline u64
max_vruntime(u64 min_vruntime
, u64 vruntime
)
430 s64 delta
= (s64
)(vruntime
- min_vruntime
);
432 min_vruntime
= vruntime
;
437 static inline u64
min_vruntime(u64 min_vruntime
, u64 vruntime
)
439 s64 delta
= (s64
)(vruntime
- min_vruntime
);
441 min_vruntime
= vruntime
;
446 static inline int entity_before(struct sched_entity
*a
,
447 struct sched_entity
*b
)
449 return (s64
)(a
->vruntime
- b
->vruntime
) < 0;
452 static void update_min_vruntime(struct cfs_rq
*cfs_rq
)
454 u64 vruntime
= cfs_rq
->min_vruntime
;
457 vruntime
= cfs_rq
->curr
->vruntime
;
459 if (cfs_rq
->rb_leftmost
) {
460 struct sched_entity
*se
= rb_entry(cfs_rq
->rb_leftmost
,
465 vruntime
= se
->vruntime
;
467 vruntime
= min_vruntime(vruntime
, se
->vruntime
);
470 cfs_rq
->min_vruntime
= max_vruntime(cfs_rq
->min_vruntime
, vruntime
);
473 cfs_rq
->min_vruntime_copy
= cfs_rq
->min_vruntime
;
478 * Enqueue an entity into the rb-tree:
480 static void __enqueue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
482 struct rb_node
**link
= &cfs_rq
->tasks_timeline
.rb_node
;
483 struct rb_node
*parent
= NULL
;
484 struct sched_entity
*entry
;
488 * Find the right place in the rbtree:
492 entry
= rb_entry(parent
, struct sched_entity
, run_node
);
494 * We dont care about collisions. Nodes with
495 * the same key stay together.
497 if (entity_before(se
, entry
)) {
498 link
= &parent
->rb_left
;
500 link
= &parent
->rb_right
;
506 * Maintain a cache of leftmost tree entries (it is frequently
510 cfs_rq
->rb_leftmost
= &se
->run_node
;
512 rb_link_node(&se
->run_node
, parent
, link
);
513 rb_insert_color(&se
->run_node
, &cfs_rq
->tasks_timeline
);
516 static void __dequeue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
518 if (cfs_rq
->rb_leftmost
== &se
->run_node
) {
519 struct rb_node
*next_node
;
521 next_node
= rb_next(&se
->run_node
);
522 cfs_rq
->rb_leftmost
= next_node
;
525 rb_erase(&se
->run_node
, &cfs_rq
->tasks_timeline
);
528 struct sched_entity
*__pick_first_entity(struct cfs_rq
*cfs_rq
)
530 struct rb_node
*left
= cfs_rq
->rb_leftmost
;
535 return rb_entry(left
, struct sched_entity
, run_node
);
538 static struct sched_entity
*__pick_next_entity(struct sched_entity
*se
)
540 struct rb_node
*next
= rb_next(&se
->run_node
);
545 return rb_entry(next
, struct sched_entity
, run_node
);
548 #ifdef CONFIG_SCHED_DEBUG
549 struct sched_entity
*__pick_last_entity(struct cfs_rq
*cfs_rq
)
551 struct rb_node
*last
= rb_last(&cfs_rq
->tasks_timeline
);
556 return rb_entry(last
, struct sched_entity
, run_node
);
559 /**************************************************************
560 * Scheduling class statistics methods:
563 int sched_proc_update_handler(struct ctl_table
*table
, int write
,
564 void __user
*buffer
, size_t *lenp
,
567 int ret
= proc_dointvec_minmax(table
, write
, buffer
, lenp
, ppos
);
568 int factor
= get_update_sysctl_factor();
573 sched_nr_latency
= DIV_ROUND_UP(sysctl_sched_latency
,
574 sysctl_sched_min_granularity
);
576 #define WRT_SYSCTL(name) \
577 (normalized_sysctl_##name = sysctl_##name / (factor))
578 WRT_SYSCTL(sched_min_granularity
);
579 WRT_SYSCTL(sched_latency
);
580 WRT_SYSCTL(sched_wakeup_granularity
);
590 static inline unsigned long
591 calc_delta_fair(unsigned long delta
, struct sched_entity
*se
)
593 if (unlikely(se
->load
.weight
!= NICE_0_LOAD
))
594 delta
= calc_delta_mine(delta
, NICE_0_LOAD
, &se
->load
);
600 * The idea is to set a period in which each task runs once.
602 * When there are too many tasks (sched_nr_latency) we have to stretch
603 * this period because otherwise the slices get too small.
605 * p = (nr <= nl) ? l : l*nr/nl
607 static u64
__sched_period(unsigned long nr_running
)
609 u64 period
= sysctl_sched_latency
;
610 unsigned long nr_latency
= sched_nr_latency
;
612 if (unlikely(nr_running
> nr_latency
)) {
613 period
= sysctl_sched_min_granularity
;
614 period
*= nr_running
;
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_mine(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
);
658 static void update_cfs_load(struct cfs_rq
*cfs_rq
, int global_update
);
659 static void update_cfs_shares(struct cfs_rq
*cfs_rq
);
662 * Update the current task's runtime statistics. Skip current tasks that
663 * are not in our scheduling class.
666 __update_curr(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
,
667 unsigned long delta_exec
)
669 unsigned long delta_exec_weighted
;
671 schedstat_set(curr
->statistics
.exec_max
,
672 max((u64
)delta_exec
, curr
->statistics
.exec_max
));
674 curr
->sum_exec_runtime
+= delta_exec
;
675 schedstat_add(cfs_rq
, exec_clock
, delta_exec
);
676 delta_exec_weighted
= calc_delta_fair(delta_exec
, curr
);
678 curr
->vruntime
+= delta_exec_weighted
;
679 update_min_vruntime(cfs_rq
);
681 #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
682 cfs_rq
->load_unacc_exec_time
+= delta_exec
;
686 static void update_curr(struct cfs_rq
*cfs_rq
)
688 struct sched_entity
*curr
= cfs_rq
->curr
;
689 u64 now
= rq_of(cfs_rq
)->clock_task
;
690 unsigned long delta_exec
;
696 * Get the amount of time the current task was running
697 * since the last time we changed load (this cannot
698 * overflow on 32 bits):
700 delta_exec
= (unsigned long)(now
- curr
->exec_start
);
704 __update_curr(cfs_rq
, curr
, delta_exec
);
705 curr
->exec_start
= now
;
707 if (entity_is_task(curr
)) {
708 struct task_struct
*curtask
= task_of(curr
);
710 trace_sched_stat_runtime(curtask
, delta_exec
, curr
->vruntime
);
711 cpuacct_charge(curtask
, delta_exec
);
712 account_group_exec_runtime(curtask
, delta_exec
);
715 account_cfs_rq_runtime(cfs_rq
, delta_exec
);
719 update_stats_wait_start(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
721 schedstat_set(se
->statistics
.wait_start
, rq_of(cfs_rq
)->clock
);
725 * Task is being enqueued - update stats:
727 static void update_stats_enqueue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
730 * Are we enqueueing a waiting task? (for current tasks
731 * a dequeue/enqueue event is a NOP)
733 if (se
!= cfs_rq
->curr
)
734 update_stats_wait_start(cfs_rq
, se
);
738 update_stats_wait_end(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
740 schedstat_set(se
->statistics
.wait_max
, max(se
->statistics
.wait_max
,
741 rq_of(cfs_rq
)->clock
- se
->statistics
.wait_start
));
742 schedstat_set(se
->statistics
.wait_count
, se
->statistics
.wait_count
+ 1);
743 schedstat_set(se
->statistics
.wait_sum
, se
->statistics
.wait_sum
+
744 rq_of(cfs_rq
)->clock
- se
->statistics
.wait_start
);
745 #ifdef CONFIG_SCHEDSTATS
746 if (entity_is_task(se
)) {
747 trace_sched_stat_wait(task_of(se
),
748 rq_of(cfs_rq
)->clock
- se
->statistics
.wait_start
);
751 schedstat_set(se
->statistics
.wait_start
, 0);
755 update_stats_dequeue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
758 * Mark the end of the wait period if dequeueing a
761 if (se
!= cfs_rq
->curr
)
762 update_stats_wait_end(cfs_rq
, se
);
766 * We are picking a new current task - update its stats:
769 update_stats_curr_start(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
772 * We are starting a new run period:
774 se
->exec_start
= rq_of(cfs_rq
)->clock_task
;
777 /**************************************************
778 * Scheduling class queueing methods:
781 #ifdef CONFIG_NUMA_BALANCING
783 * numa task sample period in ms: 5s
785 unsigned int sysctl_numa_balancing_scan_period_min
= 5000;
786 unsigned int sysctl_numa_balancing_scan_period_max
= 5000*16;
788 static void task_numa_placement(struct task_struct
*p
)
790 int seq
= ACCESS_ONCE(p
->mm
->numa_scan_seq
);
792 if (p
->numa_scan_seq
== seq
)
794 p
->numa_scan_seq
= seq
;
796 /* FIXME: Scheduling placement policy hints go here */
800 * Got a PROT_NONE fault for a page on @node.
802 void task_numa_fault(int node
, int pages
)
804 struct task_struct
*p
= current
;
806 /* FIXME: Allocate task-specific structure for placement policy here */
808 task_numa_placement(p
);
812 * The expensive part of numa migration is done from task_work context.
813 * Triggered from task_tick_numa().
815 void task_numa_work(struct callback_head
*work
)
817 unsigned long migrate
, next_scan
, now
= jiffies
;
818 struct task_struct
*p
= current
;
819 struct mm_struct
*mm
= p
->mm
;
821 WARN_ON_ONCE(p
!= container_of(work
, struct task_struct
, numa_work
));
823 work
->next
= work
; /* protect against double add */
825 * Who cares about NUMA placement when they're dying.
827 * NOTE: make sure not to dereference p->mm before this check,
828 * exit_task_work() happens _after_ exit_mm() so we could be called
829 * without p->mm even though we still had it when we enqueued this
832 if (p
->flags
& PF_EXITING
)
836 * Enforce maximal scan/migration frequency..
838 migrate
= mm
->numa_next_scan
;
839 if (time_before(now
, migrate
))
842 if (p
->numa_scan_period
== 0)
843 p
->numa_scan_period
= sysctl_numa_balancing_scan_period_min
;
845 next_scan
= now
+ 2*msecs_to_jiffies(p
->numa_scan_period
);
846 if (cmpxchg(&mm
->numa_next_scan
, migrate
, next_scan
) != migrate
)
849 ACCESS_ONCE(mm
->numa_scan_seq
)++;
851 struct vm_area_struct
*vma
;
853 down_read(&mm
->mmap_sem
);
854 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
855 if (!vma_migratable(vma
))
857 change_prot_numa(vma
, vma
->vm_start
, vma
->vm_end
);
859 up_read(&mm
->mmap_sem
);
864 * Drive the periodic memory faults..
866 void task_tick_numa(struct rq
*rq
, struct task_struct
*curr
)
868 struct callback_head
*work
= &curr
->numa_work
;
872 * We don't care about NUMA placement if we don't have memory.
874 if (!curr
->mm
|| (curr
->flags
& PF_EXITING
) || work
->next
!= work
)
878 * Using runtime rather than walltime has the dual advantage that
879 * we (mostly) drive the selection from busy threads and that the
880 * task needs to have done some actual work before we bother with
883 now
= curr
->se
.sum_exec_runtime
;
884 period
= (u64
)curr
->numa_scan_period
* NSEC_PER_MSEC
;
886 if (now
- curr
->node_stamp
> period
) {
887 curr
->node_stamp
= now
;
889 if (!time_before(jiffies
, curr
->mm
->numa_next_scan
)) {
890 init_task_work(work
, task_numa_work
); /* TODO: move this into sched_fork() */
891 task_work_add(curr
, work
, true);
896 static void task_tick_numa(struct rq
*rq
, struct task_struct
*curr
)
899 #endif /* CONFIG_NUMA_BALANCING */
902 account_entity_enqueue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
904 update_load_add(&cfs_rq
->load
, se
->load
.weight
);
905 if (!parent_entity(se
))
906 update_load_add(&rq_of(cfs_rq
)->load
, se
->load
.weight
);
908 if (entity_is_task(se
))
909 list_add(&se
->group_node
, &rq_of(cfs_rq
)->cfs_tasks
);
911 cfs_rq
->nr_running
++;
915 account_entity_dequeue(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
917 update_load_sub(&cfs_rq
->load
, se
->load
.weight
);
918 if (!parent_entity(se
))
919 update_load_sub(&rq_of(cfs_rq
)->load
, se
->load
.weight
);
920 if (entity_is_task(se
))
921 list_del_init(&se
->group_node
);
922 cfs_rq
->nr_running
--;
925 #ifdef CONFIG_FAIR_GROUP_SCHED
926 /* we need this in update_cfs_load and load-balance functions below */
927 static inline int throttled_hierarchy(struct cfs_rq
*cfs_rq
);
929 static void update_cfs_rq_load_contribution(struct cfs_rq
*cfs_rq
,
932 struct task_group
*tg
= cfs_rq
->tg
;
935 load_avg
= div64_u64(cfs_rq
->load_avg
, cfs_rq
->load_period
+1);
936 load_avg
-= cfs_rq
->load_contribution
;
938 if (global_update
|| abs(load_avg
) > cfs_rq
->load_contribution
/ 8) {
939 atomic_add(load_avg
, &tg
->load_weight
);
940 cfs_rq
->load_contribution
+= load_avg
;
944 static void update_cfs_load(struct cfs_rq
*cfs_rq
, int global_update
)
946 u64 period
= sysctl_sched_shares_window
;
948 unsigned long load
= cfs_rq
->load
.weight
;
950 if (cfs_rq
->tg
== &root_task_group
|| throttled_hierarchy(cfs_rq
))
953 now
= rq_of(cfs_rq
)->clock_task
;
954 delta
= now
- cfs_rq
->load_stamp
;
956 /* truncate load history at 4 idle periods */
957 if (cfs_rq
->load_stamp
> cfs_rq
->load_last
&&
958 now
- cfs_rq
->load_last
> 4 * period
) {
959 cfs_rq
->load_period
= 0;
960 cfs_rq
->load_avg
= 0;
964 cfs_rq
->load_stamp
= now
;
965 cfs_rq
->load_unacc_exec_time
= 0;
966 cfs_rq
->load_period
+= delta
;
968 cfs_rq
->load_last
= now
;
969 cfs_rq
->load_avg
+= delta
* load
;
972 /* consider updating load contribution on each fold or truncate */
973 if (global_update
|| cfs_rq
->load_period
> period
974 || !cfs_rq
->load_period
)
975 update_cfs_rq_load_contribution(cfs_rq
, global_update
);
977 while (cfs_rq
->load_period
> period
) {
979 * Inline assembly required to prevent the compiler
980 * optimising this loop into a divmod call.
981 * See __iter_div_u64_rem() for another example of this.
983 asm("" : "+rm" (cfs_rq
->load_period
));
984 cfs_rq
->load_period
/= 2;
985 cfs_rq
->load_avg
/= 2;
988 if (!cfs_rq
->curr
&& !cfs_rq
->nr_running
&& !cfs_rq
->load_avg
)
989 list_del_leaf_cfs_rq(cfs_rq
);
992 static inline long calc_tg_weight(struct task_group
*tg
, struct cfs_rq
*cfs_rq
)
997 * Use this CPU's actual weight instead of the last load_contribution
998 * to gain a more accurate current total weight. See
999 * update_cfs_rq_load_contribution().
1001 tg_weight
= atomic_read(&tg
->load_weight
);
1002 tg_weight
-= cfs_rq
->load_contribution
;
1003 tg_weight
+= cfs_rq
->load
.weight
;
1008 static long calc_cfs_shares(struct cfs_rq
*cfs_rq
, struct task_group
*tg
)
1010 long tg_weight
, load
, shares
;
1012 tg_weight
= calc_tg_weight(tg
, cfs_rq
);
1013 load
= cfs_rq
->load
.weight
;
1015 shares
= (tg
->shares
* load
);
1017 shares
/= tg_weight
;
1019 if (shares
< MIN_SHARES
)
1020 shares
= MIN_SHARES
;
1021 if (shares
> tg
->shares
)
1022 shares
= tg
->shares
;
1027 static void update_entity_shares_tick(struct cfs_rq
*cfs_rq
)
1029 if (cfs_rq
->load_unacc_exec_time
> sysctl_sched_shares_window
) {
1030 update_cfs_load(cfs_rq
, 0);
1031 update_cfs_shares(cfs_rq
);
1034 # else /* CONFIG_SMP */
1035 static void update_cfs_load(struct cfs_rq
*cfs_rq
, int global_update
)
1039 static inline long calc_cfs_shares(struct cfs_rq
*cfs_rq
, struct task_group
*tg
)
1044 static inline void update_entity_shares_tick(struct cfs_rq
*cfs_rq
)
1047 # endif /* CONFIG_SMP */
1048 static void reweight_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
,
1049 unsigned long weight
)
1052 /* commit outstanding execution time */
1053 if (cfs_rq
->curr
== se
)
1054 update_curr(cfs_rq
);
1055 account_entity_dequeue(cfs_rq
, se
);
1058 update_load_set(&se
->load
, weight
);
1061 account_entity_enqueue(cfs_rq
, se
);
1064 static void update_cfs_shares(struct cfs_rq
*cfs_rq
)
1066 struct task_group
*tg
;
1067 struct sched_entity
*se
;
1071 se
= tg
->se
[cpu_of(rq_of(cfs_rq
))];
1072 if (!se
|| throttled_hierarchy(cfs_rq
))
1075 if (likely(se
->load
.weight
== tg
->shares
))
1078 shares
= calc_cfs_shares(cfs_rq
, tg
);
1080 reweight_entity(cfs_rq_of(se
), se
, shares
);
1082 #else /* CONFIG_FAIR_GROUP_SCHED */
1083 static void update_cfs_load(struct cfs_rq
*cfs_rq
, int global_update
)
1087 static inline void update_cfs_shares(struct cfs_rq
*cfs_rq
)
1091 static inline void update_entity_shares_tick(struct cfs_rq
*cfs_rq
)
1094 #endif /* CONFIG_FAIR_GROUP_SCHED */
1096 static void enqueue_sleeper(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
1098 #ifdef CONFIG_SCHEDSTATS
1099 struct task_struct
*tsk
= NULL
;
1101 if (entity_is_task(se
))
1104 if (se
->statistics
.sleep_start
) {
1105 u64 delta
= rq_of(cfs_rq
)->clock
- se
->statistics
.sleep_start
;
1110 if (unlikely(delta
> se
->statistics
.sleep_max
))
1111 se
->statistics
.sleep_max
= delta
;
1113 se
->statistics
.sleep_start
= 0;
1114 se
->statistics
.sum_sleep_runtime
+= delta
;
1117 account_scheduler_latency(tsk
, delta
>> 10, 1);
1118 trace_sched_stat_sleep(tsk
, delta
);
1121 if (se
->statistics
.block_start
) {
1122 u64 delta
= rq_of(cfs_rq
)->clock
- se
->statistics
.block_start
;
1127 if (unlikely(delta
> se
->statistics
.block_max
))
1128 se
->statistics
.block_max
= delta
;
1130 se
->statistics
.block_start
= 0;
1131 se
->statistics
.sum_sleep_runtime
+= delta
;
1134 if (tsk
->in_iowait
) {
1135 se
->statistics
.iowait_sum
+= delta
;
1136 se
->statistics
.iowait_count
++;
1137 trace_sched_stat_iowait(tsk
, delta
);
1140 trace_sched_stat_blocked(tsk
, delta
);
1143 * Blocking time is in units of nanosecs, so shift by
1144 * 20 to get a milliseconds-range estimation of the
1145 * amount of time that the task spent sleeping:
1147 if (unlikely(prof_on
== SLEEP_PROFILING
)) {
1148 profile_hits(SLEEP_PROFILING
,
1149 (void *)get_wchan(tsk
),
1152 account_scheduler_latency(tsk
, delta
>> 10, 0);
1158 static void check_spread(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
1160 #ifdef CONFIG_SCHED_DEBUG
1161 s64 d
= se
->vruntime
- cfs_rq
->min_vruntime
;
1166 if (d
> 3*sysctl_sched_latency
)
1167 schedstat_inc(cfs_rq
, nr_spread_over
);
1172 place_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int initial
)
1174 u64 vruntime
= cfs_rq
->min_vruntime
;
1177 * The 'current' period is already promised to the current tasks,
1178 * however the extra weight of the new task will slow them down a
1179 * little, place the new task so that it fits in the slot that
1180 * stays open at the end.
1182 if (initial
&& sched_feat(START_DEBIT
))
1183 vruntime
+= sched_vslice(cfs_rq
, se
);
1185 /* sleeps up to a single latency don't count. */
1187 unsigned long thresh
= sysctl_sched_latency
;
1190 * Halve their sleep time's effect, to allow
1191 * for a gentler effect of sleepers:
1193 if (sched_feat(GENTLE_FAIR_SLEEPERS
))
1199 /* ensure we never gain time by being placed backwards. */
1200 vruntime
= max_vruntime(se
->vruntime
, vruntime
);
1202 se
->vruntime
= vruntime
;
1205 static void check_enqueue_throttle(struct cfs_rq
*cfs_rq
);
1208 enqueue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int flags
)
1211 * Update the normalized vruntime before updating min_vruntime
1212 * through callig update_curr().
1214 if (!(flags
& ENQUEUE_WAKEUP
) || (flags
& ENQUEUE_WAKING
))
1215 se
->vruntime
+= cfs_rq
->min_vruntime
;
1218 * Update run-time statistics of the 'current'.
1220 update_curr(cfs_rq
);
1221 update_cfs_load(cfs_rq
, 0);
1222 account_entity_enqueue(cfs_rq
, se
);
1223 update_cfs_shares(cfs_rq
);
1225 if (flags
& ENQUEUE_WAKEUP
) {
1226 place_entity(cfs_rq
, se
, 0);
1227 enqueue_sleeper(cfs_rq
, se
);
1230 update_stats_enqueue(cfs_rq
, se
);
1231 check_spread(cfs_rq
, se
);
1232 if (se
!= cfs_rq
->curr
)
1233 __enqueue_entity(cfs_rq
, se
);
1236 if (cfs_rq
->nr_running
== 1) {
1237 list_add_leaf_cfs_rq(cfs_rq
);
1238 check_enqueue_throttle(cfs_rq
);
1242 static void __clear_buddies_last(struct sched_entity
*se
)
1244 for_each_sched_entity(se
) {
1245 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
1246 if (cfs_rq
->last
== se
)
1247 cfs_rq
->last
= NULL
;
1253 static void __clear_buddies_next(struct sched_entity
*se
)
1255 for_each_sched_entity(se
) {
1256 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
1257 if (cfs_rq
->next
== se
)
1258 cfs_rq
->next
= NULL
;
1264 static void __clear_buddies_skip(struct sched_entity
*se
)
1266 for_each_sched_entity(se
) {
1267 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
1268 if (cfs_rq
->skip
== se
)
1269 cfs_rq
->skip
= NULL
;
1275 static void clear_buddies(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
1277 if (cfs_rq
->last
== se
)
1278 __clear_buddies_last(se
);
1280 if (cfs_rq
->next
== se
)
1281 __clear_buddies_next(se
);
1283 if (cfs_rq
->skip
== se
)
1284 __clear_buddies_skip(se
);
1287 static __always_inline
void return_cfs_rq_runtime(struct cfs_rq
*cfs_rq
);
1290 dequeue_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
, int flags
)
1293 * Update run-time statistics of the 'current'.
1295 update_curr(cfs_rq
);
1297 update_stats_dequeue(cfs_rq
, se
);
1298 if (flags
& DEQUEUE_SLEEP
) {
1299 #ifdef CONFIG_SCHEDSTATS
1300 if (entity_is_task(se
)) {
1301 struct task_struct
*tsk
= task_of(se
);
1303 if (tsk
->state
& TASK_INTERRUPTIBLE
)
1304 se
->statistics
.sleep_start
= rq_of(cfs_rq
)->clock
;
1305 if (tsk
->state
& TASK_UNINTERRUPTIBLE
)
1306 se
->statistics
.block_start
= rq_of(cfs_rq
)->clock
;
1311 clear_buddies(cfs_rq
, se
);
1313 if (se
!= cfs_rq
->curr
)
1314 __dequeue_entity(cfs_rq
, se
);
1316 update_cfs_load(cfs_rq
, 0);
1317 account_entity_dequeue(cfs_rq
, se
);
1320 * Normalize the entity after updating the min_vruntime because the
1321 * update can refer to the ->curr item and we need to reflect this
1322 * movement in our normalized position.
1324 if (!(flags
& DEQUEUE_SLEEP
))
1325 se
->vruntime
-= cfs_rq
->min_vruntime
;
1327 /* return excess runtime on last dequeue */
1328 return_cfs_rq_runtime(cfs_rq
);
1330 update_min_vruntime(cfs_rq
);
1331 update_cfs_shares(cfs_rq
);
1335 * Preempt the current task with a newly woken task if needed:
1338 check_preempt_tick(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
)
1340 unsigned long ideal_runtime
, delta_exec
;
1341 struct sched_entity
*se
;
1344 ideal_runtime
= sched_slice(cfs_rq
, curr
);
1345 delta_exec
= curr
->sum_exec_runtime
- curr
->prev_sum_exec_runtime
;
1346 if (delta_exec
> ideal_runtime
) {
1347 resched_task(rq_of(cfs_rq
)->curr
);
1349 * The current task ran long enough, ensure it doesn't get
1350 * re-elected due to buddy favours.
1352 clear_buddies(cfs_rq
, curr
);
1357 * Ensure that a task that missed wakeup preemption by a
1358 * narrow margin doesn't have to wait for a full slice.
1359 * This also mitigates buddy induced latencies under load.
1361 if (delta_exec
< sysctl_sched_min_granularity
)
1364 se
= __pick_first_entity(cfs_rq
);
1365 delta
= curr
->vruntime
- se
->vruntime
;
1370 if (delta
> ideal_runtime
)
1371 resched_task(rq_of(cfs_rq
)->curr
);
1375 set_next_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*se
)
1377 /* 'current' is not kept within the tree. */
1380 * Any task has to be enqueued before it get to execute on
1381 * a CPU. So account for the time it spent waiting on the
1384 update_stats_wait_end(cfs_rq
, se
);
1385 __dequeue_entity(cfs_rq
, se
);
1388 update_stats_curr_start(cfs_rq
, se
);
1390 #ifdef CONFIG_SCHEDSTATS
1392 * Track our maximum slice length, if the CPU's load is at
1393 * least twice that of our own weight (i.e. dont track it
1394 * when there are only lesser-weight tasks around):
1396 if (rq_of(cfs_rq
)->load
.weight
>= 2*se
->load
.weight
) {
1397 se
->statistics
.slice_max
= max(se
->statistics
.slice_max
,
1398 se
->sum_exec_runtime
- se
->prev_sum_exec_runtime
);
1401 se
->prev_sum_exec_runtime
= se
->sum_exec_runtime
;
1405 wakeup_preempt_entity(struct sched_entity
*curr
, struct sched_entity
*se
);
1408 * Pick the next process, keeping these things in mind, in this order:
1409 * 1) keep things fair between processes/task groups
1410 * 2) pick the "next" process, since someone really wants that to run
1411 * 3) pick the "last" process, for cache locality
1412 * 4) do not run the "skip" process, if something else is available
1414 static struct sched_entity
*pick_next_entity(struct cfs_rq
*cfs_rq
)
1416 struct sched_entity
*se
= __pick_first_entity(cfs_rq
);
1417 struct sched_entity
*left
= se
;
1420 * Avoid running the skip buddy, if running something else can
1421 * be done without getting too unfair.
1423 if (cfs_rq
->skip
== se
) {
1424 struct sched_entity
*second
= __pick_next_entity(se
);
1425 if (second
&& wakeup_preempt_entity(second
, left
) < 1)
1430 * Prefer last buddy, try to return the CPU to a preempted task.
1432 if (cfs_rq
->last
&& wakeup_preempt_entity(cfs_rq
->last
, left
) < 1)
1436 * Someone really wants this to run. If it's not unfair, run it.
1438 if (cfs_rq
->next
&& wakeup_preempt_entity(cfs_rq
->next
, left
) < 1)
1441 clear_buddies(cfs_rq
, se
);
1446 static void check_cfs_rq_runtime(struct cfs_rq
*cfs_rq
);
1448 static void put_prev_entity(struct cfs_rq
*cfs_rq
, struct sched_entity
*prev
)
1451 * If still on the runqueue then deactivate_task()
1452 * was not called and update_curr() has to be done:
1455 update_curr(cfs_rq
);
1457 /* throttle cfs_rqs exceeding runtime */
1458 check_cfs_rq_runtime(cfs_rq
);
1460 check_spread(cfs_rq
, prev
);
1462 update_stats_wait_start(cfs_rq
, prev
);
1463 /* Put 'current' back into the tree. */
1464 __enqueue_entity(cfs_rq
, prev
);
1466 cfs_rq
->curr
= NULL
;
1470 entity_tick(struct cfs_rq
*cfs_rq
, struct sched_entity
*curr
, int queued
)
1473 * Update run-time statistics of the 'current'.
1475 update_curr(cfs_rq
);
1478 * Update share accounting for long-running entities.
1480 update_entity_shares_tick(cfs_rq
);
1482 #ifdef CONFIG_SCHED_HRTICK
1484 * queued ticks are scheduled to match the slice, so don't bother
1485 * validating it and just reschedule.
1488 resched_task(rq_of(cfs_rq
)->curr
);
1492 * don't let the period tick interfere with the hrtick preemption
1494 if (!sched_feat(DOUBLE_TICK
) &&
1495 hrtimer_active(&rq_of(cfs_rq
)->hrtick_timer
))
1499 if (cfs_rq
->nr_running
> 1)
1500 check_preempt_tick(cfs_rq
, curr
);
1504 /**************************************************
1505 * CFS bandwidth control machinery
1508 #ifdef CONFIG_CFS_BANDWIDTH
1510 #ifdef HAVE_JUMP_LABEL
1511 static struct static_key __cfs_bandwidth_used
;
1513 static inline bool cfs_bandwidth_used(void)
1515 return static_key_false(&__cfs_bandwidth_used
);
1518 void account_cfs_bandwidth_used(int enabled
, int was_enabled
)
1520 /* only need to count groups transitioning between enabled/!enabled */
1521 if (enabled
&& !was_enabled
)
1522 static_key_slow_inc(&__cfs_bandwidth_used
);
1523 else if (!enabled
&& was_enabled
)
1524 static_key_slow_dec(&__cfs_bandwidth_used
);
1526 #else /* HAVE_JUMP_LABEL */
1527 static bool cfs_bandwidth_used(void)
1532 void account_cfs_bandwidth_used(int enabled
, int was_enabled
) {}
1533 #endif /* HAVE_JUMP_LABEL */
1536 * default period for cfs group bandwidth.
1537 * default: 0.1s, units: nanoseconds
1539 static inline u64
default_cfs_period(void)
1541 return 100000000ULL;
1544 static inline u64
sched_cfs_bandwidth_slice(void)
1546 return (u64
)sysctl_sched_cfs_bandwidth_slice
* NSEC_PER_USEC
;
1550 * Replenish runtime according to assigned quota and update expiration time.
1551 * We use sched_clock_cpu directly instead of rq->clock to avoid adding
1552 * additional synchronization around rq->lock.
1554 * requires cfs_b->lock
1556 void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth
*cfs_b
)
1560 if (cfs_b
->quota
== RUNTIME_INF
)
1563 now
= sched_clock_cpu(smp_processor_id());
1564 cfs_b
->runtime
= cfs_b
->quota
;
1565 cfs_b
->runtime_expires
= now
+ ktime_to_ns(cfs_b
->period
);
1568 static inline struct cfs_bandwidth
*tg_cfs_bandwidth(struct task_group
*tg
)
1570 return &tg
->cfs_bandwidth
;
1573 /* returns 0 on failure to allocate runtime */
1574 static int assign_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
1576 struct task_group
*tg
= cfs_rq
->tg
;
1577 struct cfs_bandwidth
*cfs_b
= tg_cfs_bandwidth(tg
);
1578 u64 amount
= 0, min_amount
, expires
;
1580 /* note: this is a positive sum as runtime_remaining <= 0 */
1581 min_amount
= sched_cfs_bandwidth_slice() - cfs_rq
->runtime_remaining
;
1583 raw_spin_lock(&cfs_b
->lock
);
1584 if (cfs_b
->quota
== RUNTIME_INF
)
1585 amount
= min_amount
;
1588 * If the bandwidth pool has become inactive, then at least one
1589 * period must have elapsed since the last consumption.
1590 * Refresh the global state and ensure bandwidth timer becomes
1593 if (!cfs_b
->timer_active
) {
1594 __refill_cfs_bandwidth_runtime(cfs_b
);
1595 __start_cfs_bandwidth(cfs_b
);
1598 if (cfs_b
->runtime
> 0) {
1599 amount
= min(cfs_b
->runtime
, min_amount
);
1600 cfs_b
->runtime
-= amount
;
1604 expires
= cfs_b
->runtime_expires
;
1605 raw_spin_unlock(&cfs_b
->lock
);
1607 cfs_rq
->runtime_remaining
+= amount
;
1609 * we may have advanced our local expiration to account for allowed
1610 * spread between our sched_clock and the one on which runtime was
1613 if ((s64
)(expires
- cfs_rq
->runtime_expires
) > 0)
1614 cfs_rq
->runtime_expires
= expires
;
1616 return cfs_rq
->runtime_remaining
> 0;
1620 * Note: This depends on the synchronization provided by sched_clock and the
1621 * fact that rq->clock snapshots this value.
1623 static void expire_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
1625 struct cfs_bandwidth
*cfs_b
= tg_cfs_bandwidth(cfs_rq
->tg
);
1626 struct rq
*rq
= rq_of(cfs_rq
);
1628 /* if the deadline is ahead of our clock, nothing to do */
1629 if (likely((s64
)(rq
->clock
- cfs_rq
->runtime_expires
) < 0))
1632 if (cfs_rq
->runtime_remaining
< 0)
1636 * If the local deadline has passed we have to consider the
1637 * possibility that our sched_clock is 'fast' and the global deadline
1638 * has not truly expired.
1640 * Fortunately we can check determine whether this the case by checking
1641 * whether the global deadline has advanced.
1644 if ((s64
)(cfs_rq
->runtime_expires
- cfs_b
->runtime_expires
) >= 0) {
1645 /* extend local deadline, drift is bounded above by 2 ticks */
1646 cfs_rq
->runtime_expires
+= TICK_NSEC
;
1648 /* global deadline is ahead, expiration has passed */
1649 cfs_rq
->runtime_remaining
= 0;
1653 static void __account_cfs_rq_runtime(struct cfs_rq
*cfs_rq
,
1654 unsigned long delta_exec
)
1656 /* dock delta_exec before expiring quota (as it could span periods) */
1657 cfs_rq
->runtime_remaining
-= delta_exec
;
1658 expire_cfs_rq_runtime(cfs_rq
);
1660 if (likely(cfs_rq
->runtime_remaining
> 0))
1664 * if we're unable to extend our runtime we resched so that the active
1665 * hierarchy can be throttled
1667 if (!assign_cfs_rq_runtime(cfs_rq
) && likely(cfs_rq
->curr
))
1668 resched_task(rq_of(cfs_rq
)->curr
);
1671 static __always_inline
1672 void account_cfs_rq_runtime(struct cfs_rq
*cfs_rq
, unsigned long delta_exec
)
1674 if (!cfs_bandwidth_used() || !cfs_rq
->runtime_enabled
)
1677 __account_cfs_rq_runtime(cfs_rq
, delta_exec
);
1680 static inline int cfs_rq_throttled(struct cfs_rq
*cfs_rq
)
1682 return cfs_bandwidth_used() && cfs_rq
->throttled
;
1685 /* check whether cfs_rq, or any parent, is throttled */
1686 static inline int throttled_hierarchy(struct cfs_rq
*cfs_rq
)
1688 return cfs_bandwidth_used() && cfs_rq
->throttle_count
;
1692 * Ensure that neither of the group entities corresponding to src_cpu or
1693 * dest_cpu are members of a throttled hierarchy when performing group
1694 * load-balance operations.
1696 static inline int throttled_lb_pair(struct task_group
*tg
,
1697 int src_cpu
, int dest_cpu
)
1699 struct cfs_rq
*src_cfs_rq
, *dest_cfs_rq
;
1701 src_cfs_rq
= tg
->cfs_rq
[src_cpu
];
1702 dest_cfs_rq
= tg
->cfs_rq
[dest_cpu
];
1704 return throttled_hierarchy(src_cfs_rq
) ||
1705 throttled_hierarchy(dest_cfs_rq
);
1708 /* updated child weight may affect parent so we have to do this bottom up */
1709 static int tg_unthrottle_up(struct task_group
*tg
, void *data
)
1711 struct rq
*rq
= data
;
1712 struct cfs_rq
*cfs_rq
= tg
->cfs_rq
[cpu_of(rq
)];
1714 cfs_rq
->throttle_count
--;
1716 if (!cfs_rq
->throttle_count
) {
1717 u64 delta
= rq
->clock_task
- cfs_rq
->load_stamp
;
1719 /* leaving throttled state, advance shares averaging windows */
1720 cfs_rq
->load_stamp
+= delta
;
1721 cfs_rq
->load_last
+= delta
;
1723 /* update entity weight now that we are on_rq again */
1724 update_cfs_shares(cfs_rq
);
1731 static int tg_throttle_down(struct task_group
*tg
, void *data
)
1733 struct rq
*rq
= data
;
1734 struct cfs_rq
*cfs_rq
= tg
->cfs_rq
[cpu_of(rq
)];
1736 /* group is entering throttled state, record last load */
1737 if (!cfs_rq
->throttle_count
)
1738 update_cfs_load(cfs_rq
, 0);
1739 cfs_rq
->throttle_count
++;
1744 static void throttle_cfs_rq(struct cfs_rq
*cfs_rq
)
1746 struct rq
*rq
= rq_of(cfs_rq
);
1747 struct cfs_bandwidth
*cfs_b
= tg_cfs_bandwidth(cfs_rq
->tg
);
1748 struct sched_entity
*se
;
1749 long task_delta
, dequeue
= 1;
1751 se
= cfs_rq
->tg
->se
[cpu_of(rq_of(cfs_rq
))];
1753 /* account load preceding throttle */
1755 walk_tg_tree_from(cfs_rq
->tg
, tg_throttle_down
, tg_nop
, (void *)rq
);
1758 task_delta
= cfs_rq
->h_nr_running
;
1759 for_each_sched_entity(se
) {
1760 struct cfs_rq
*qcfs_rq
= cfs_rq_of(se
);
1761 /* throttled entity or throttle-on-deactivate */
1766 dequeue_entity(qcfs_rq
, se
, DEQUEUE_SLEEP
);
1767 qcfs_rq
->h_nr_running
-= task_delta
;
1769 if (qcfs_rq
->load
.weight
)
1774 rq
->nr_running
-= task_delta
;
1776 cfs_rq
->throttled
= 1;
1777 cfs_rq
->throttled_timestamp
= rq
->clock
;
1778 raw_spin_lock(&cfs_b
->lock
);
1779 list_add_tail_rcu(&cfs_rq
->throttled_list
, &cfs_b
->throttled_cfs_rq
);
1780 raw_spin_unlock(&cfs_b
->lock
);
1783 void unthrottle_cfs_rq(struct cfs_rq
*cfs_rq
)
1785 struct rq
*rq
= rq_of(cfs_rq
);
1786 struct cfs_bandwidth
*cfs_b
= tg_cfs_bandwidth(cfs_rq
->tg
);
1787 struct sched_entity
*se
;
1791 se
= cfs_rq
->tg
->se
[cpu_of(rq_of(cfs_rq
))];
1793 cfs_rq
->throttled
= 0;
1794 raw_spin_lock(&cfs_b
->lock
);
1795 cfs_b
->throttled_time
+= rq
->clock
- cfs_rq
->throttled_timestamp
;
1796 list_del_rcu(&cfs_rq
->throttled_list
);
1797 raw_spin_unlock(&cfs_b
->lock
);
1798 cfs_rq
->throttled_timestamp
= 0;
1800 update_rq_clock(rq
);
1801 /* update hierarchical throttle state */
1802 walk_tg_tree_from(cfs_rq
->tg
, tg_nop
, tg_unthrottle_up
, (void *)rq
);
1804 if (!cfs_rq
->load
.weight
)
1807 task_delta
= cfs_rq
->h_nr_running
;
1808 for_each_sched_entity(se
) {
1812 cfs_rq
= cfs_rq_of(se
);
1814 enqueue_entity(cfs_rq
, se
, ENQUEUE_WAKEUP
);
1815 cfs_rq
->h_nr_running
+= task_delta
;
1817 if (cfs_rq_throttled(cfs_rq
))
1822 rq
->nr_running
+= task_delta
;
1824 /* determine whether we need to wake up potentially idle cpu */
1825 if (rq
->curr
== rq
->idle
&& rq
->cfs
.nr_running
)
1826 resched_task(rq
->curr
);
1829 static u64
distribute_cfs_runtime(struct cfs_bandwidth
*cfs_b
,
1830 u64 remaining
, u64 expires
)
1832 struct cfs_rq
*cfs_rq
;
1833 u64 runtime
= remaining
;
1836 list_for_each_entry_rcu(cfs_rq
, &cfs_b
->throttled_cfs_rq
,
1838 struct rq
*rq
= rq_of(cfs_rq
);
1840 raw_spin_lock(&rq
->lock
);
1841 if (!cfs_rq_throttled(cfs_rq
))
1844 runtime
= -cfs_rq
->runtime_remaining
+ 1;
1845 if (runtime
> remaining
)
1846 runtime
= remaining
;
1847 remaining
-= runtime
;
1849 cfs_rq
->runtime_remaining
+= runtime
;
1850 cfs_rq
->runtime_expires
= expires
;
1852 /* we check whether we're throttled above */
1853 if (cfs_rq
->runtime_remaining
> 0)
1854 unthrottle_cfs_rq(cfs_rq
);
1857 raw_spin_unlock(&rq
->lock
);
1868 * Responsible for refilling a task_group's bandwidth and unthrottling its
1869 * cfs_rqs as appropriate. If there has been no activity within the last
1870 * period the timer is deactivated until scheduling resumes; cfs_b->idle is
1871 * used to track this state.
1873 static int do_sched_cfs_period_timer(struct cfs_bandwidth
*cfs_b
, int overrun
)
1875 u64 runtime
, runtime_expires
;
1876 int idle
= 1, throttled
;
1878 raw_spin_lock(&cfs_b
->lock
);
1879 /* no need to continue the timer with no bandwidth constraint */
1880 if (cfs_b
->quota
== RUNTIME_INF
)
1883 throttled
= !list_empty(&cfs_b
->throttled_cfs_rq
);
1884 /* idle depends on !throttled (for the case of a large deficit) */
1885 idle
= cfs_b
->idle
&& !throttled
;
1886 cfs_b
->nr_periods
+= overrun
;
1888 /* if we're going inactive then everything else can be deferred */
1892 __refill_cfs_bandwidth_runtime(cfs_b
);
1895 /* mark as potentially idle for the upcoming period */
1900 /* account preceding periods in which throttling occurred */
1901 cfs_b
->nr_throttled
+= overrun
;
1904 * There are throttled entities so we must first use the new bandwidth
1905 * to unthrottle them before making it generally available. This
1906 * ensures that all existing debts will be paid before a new cfs_rq is
1909 runtime
= cfs_b
->runtime
;
1910 runtime_expires
= cfs_b
->runtime_expires
;
1914 * This check is repeated as we are holding onto the new bandwidth
1915 * while we unthrottle. This can potentially race with an unthrottled
1916 * group trying to acquire new bandwidth from the global pool.
1918 while (throttled
&& runtime
> 0) {
1919 raw_spin_unlock(&cfs_b
->lock
);
1920 /* we can't nest cfs_b->lock while distributing bandwidth */
1921 runtime
= distribute_cfs_runtime(cfs_b
, runtime
,
1923 raw_spin_lock(&cfs_b
->lock
);
1925 throttled
= !list_empty(&cfs_b
->throttled_cfs_rq
);
1928 /* return (any) remaining runtime */
1929 cfs_b
->runtime
= runtime
;
1931 * While we are ensured activity in the period following an
1932 * unthrottle, this also covers the case in which the new bandwidth is
1933 * insufficient to cover the existing bandwidth deficit. (Forcing the
1934 * timer to remain active while there are any throttled entities.)
1939 cfs_b
->timer_active
= 0;
1940 raw_spin_unlock(&cfs_b
->lock
);
1945 /* a cfs_rq won't donate quota below this amount */
1946 static const u64 min_cfs_rq_runtime
= 1 * NSEC_PER_MSEC
;
1947 /* minimum remaining period time to redistribute slack quota */
1948 static const u64 min_bandwidth_expiration
= 2 * NSEC_PER_MSEC
;
1949 /* how long we wait to gather additional slack before distributing */
1950 static const u64 cfs_bandwidth_slack_period
= 5 * NSEC_PER_MSEC
;
1952 /* are we near the end of the current quota period? */
1953 static int runtime_refresh_within(struct cfs_bandwidth
*cfs_b
, u64 min_expire
)
1955 struct hrtimer
*refresh_timer
= &cfs_b
->period_timer
;
1958 /* if the call-back is running a quota refresh is already occurring */
1959 if (hrtimer_callback_running(refresh_timer
))
1962 /* is a quota refresh about to occur? */
1963 remaining
= ktime_to_ns(hrtimer_expires_remaining(refresh_timer
));
1964 if (remaining
< min_expire
)
1970 static void start_cfs_slack_bandwidth(struct cfs_bandwidth
*cfs_b
)
1972 u64 min_left
= cfs_bandwidth_slack_period
+ min_bandwidth_expiration
;
1974 /* if there's a quota refresh soon don't bother with slack */
1975 if (runtime_refresh_within(cfs_b
, min_left
))
1978 start_bandwidth_timer(&cfs_b
->slack_timer
,
1979 ns_to_ktime(cfs_bandwidth_slack_period
));
1982 /* we know any runtime found here is valid as update_curr() precedes return */
1983 static void __return_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
1985 struct cfs_bandwidth
*cfs_b
= tg_cfs_bandwidth(cfs_rq
->tg
);
1986 s64 slack_runtime
= cfs_rq
->runtime_remaining
- min_cfs_rq_runtime
;
1988 if (slack_runtime
<= 0)
1991 raw_spin_lock(&cfs_b
->lock
);
1992 if (cfs_b
->quota
!= RUNTIME_INF
&&
1993 cfs_rq
->runtime_expires
== cfs_b
->runtime_expires
) {
1994 cfs_b
->runtime
+= slack_runtime
;
1996 /* we are under rq->lock, defer unthrottling using a timer */
1997 if (cfs_b
->runtime
> sched_cfs_bandwidth_slice() &&
1998 !list_empty(&cfs_b
->throttled_cfs_rq
))
1999 start_cfs_slack_bandwidth(cfs_b
);
2001 raw_spin_unlock(&cfs_b
->lock
);
2003 /* even if it's not valid for return we don't want to try again */
2004 cfs_rq
->runtime_remaining
-= slack_runtime
;
2007 static __always_inline
void return_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
2009 if (!cfs_bandwidth_used())
2012 if (!cfs_rq
->runtime_enabled
|| cfs_rq
->nr_running
)
2015 __return_cfs_rq_runtime(cfs_rq
);
2019 * This is done with a timer (instead of inline with bandwidth return) since
2020 * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
2022 static void do_sched_cfs_slack_timer(struct cfs_bandwidth
*cfs_b
)
2024 u64 runtime
= 0, slice
= sched_cfs_bandwidth_slice();
2027 /* confirm we're still not at a refresh boundary */
2028 if (runtime_refresh_within(cfs_b
, min_bandwidth_expiration
))
2031 raw_spin_lock(&cfs_b
->lock
);
2032 if (cfs_b
->quota
!= RUNTIME_INF
&& cfs_b
->runtime
> slice
) {
2033 runtime
= cfs_b
->runtime
;
2036 expires
= cfs_b
->runtime_expires
;
2037 raw_spin_unlock(&cfs_b
->lock
);
2042 runtime
= distribute_cfs_runtime(cfs_b
, runtime
, expires
);
2044 raw_spin_lock(&cfs_b
->lock
);
2045 if (expires
== cfs_b
->runtime_expires
)
2046 cfs_b
->runtime
= runtime
;
2047 raw_spin_unlock(&cfs_b
->lock
);
2051 * When a group wakes up we want to make sure that its quota is not already
2052 * expired/exceeded, otherwise it may be allowed to steal additional ticks of
2053 * runtime as update_curr() throttling can not not trigger until it's on-rq.
2055 static void check_enqueue_throttle(struct cfs_rq
*cfs_rq
)
2057 if (!cfs_bandwidth_used())
2060 /* an active group must be handled by the update_curr()->put() path */
2061 if (!cfs_rq
->runtime_enabled
|| cfs_rq
->curr
)
2064 /* ensure the group is not already throttled */
2065 if (cfs_rq_throttled(cfs_rq
))
2068 /* update runtime allocation */
2069 account_cfs_rq_runtime(cfs_rq
, 0);
2070 if (cfs_rq
->runtime_remaining
<= 0)
2071 throttle_cfs_rq(cfs_rq
);
2074 /* conditionally throttle active cfs_rq's from put_prev_entity() */
2075 static void check_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
2077 if (!cfs_bandwidth_used())
2080 if (likely(!cfs_rq
->runtime_enabled
|| cfs_rq
->runtime_remaining
> 0))
2084 * it's possible for a throttled entity to be forced into a running
2085 * state (e.g. set_curr_task), in this case we're finished.
2087 if (cfs_rq_throttled(cfs_rq
))
2090 throttle_cfs_rq(cfs_rq
);
2093 static inline u64
default_cfs_period(void);
2094 static int do_sched_cfs_period_timer(struct cfs_bandwidth
*cfs_b
, int overrun
);
2095 static void do_sched_cfs_slack_timer(struct cfs_bandwidth
*cfs_b
);
2097 static enum hrtimer_restart
sched_cfs_slack_timer(struct hrtimer
*timer
)
2099 struct cfs_bandwidth
*cfs_b
=
2100 container_of(timer
, struct cfs_bandwidth
, slack_timer
);
2101 do_sched_cfs_slack_timer(cfs_b
);
2103 return HRTIMER_NORESTART
;
2106 static enum hrtimer_restart
sched_cfs_period_timer(struct hrtimer
*timer
)
2108 struct cfs_bandwidth
*cfs_b
=
2109 container_of(timer
, struct cfs_bandwidth
, period_timer
);
2115 now
= hrtimer_cb_get_time(timer
);
2116 overrun
= hrtimer_forward(timer
, now
, cfs_b
->period
);
2121 idle
= do_sched_cfs_period_timer(cfs_b
, overrun
);
2124 return idle
? HRTIMER_NORESTART
: HRTIMER_RESTART
;
2127 void init_cfs_bandwidth(struct cfs_bandwidth
*cfs_b
)
2129 raw_spin_lock_init(&cfs_b
->lock
);
2131 cfs_b
->quota
= RUNTIME_INF
;
2132 cfs_b
->period
= ns_to_ktime(default_cfs_period());
2134 INIT_LIST_HEAD(&cfs_b
->throttled_cfs_rq
);
2135 hrtimer_init(&cfs_b
->period_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
2136 cfs_b
->period_timer
.function
= sched_cfs_period_timer
;
2137 hrtimer_init(&cfs_b
->slack_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
2138 cfs_b
->slack_timer
.function
= sched_cfs_slack_timer
;
2141 static void init_cfs_rq_runtime(struct cfs_rq
*cfs_rq
)
2143 cfs_rq
->runtime_enabled
= 0;
2144 INIT_LIST_HEAD(&cfs_rq
->throttled_list
);
2147 /* requires cfs_b->lock, may release to reprogram timer */
2148 void __start_cfs_bandwidth(struct cfs_bandwidth
*cfs_b
)
2151 * The timer may be active because we're trying to set a new bandwidth
2152 * period or because we're racing with the tear-down path
2153 * (timer_active==0 becomes visible before the hrtimer call-back
2154 * terminates). In either case we ensure that it's re-programmed
2156 while (unlikely(hrtimer_active(&cfs_b
->period_timer
))) {
2157 raw_spin_unlock(&cfs_b
->lock
);
2158 /* ensure cfs_b->lock is available while we wait */
2159 hrtimer_cancel(&cfs_b
->period_timer
);
2161 raw_spin_lock(&cfs_b
->lock
);
2162 /* if someone else restarted the timer then we're done */
2163 if (cfs_b
->timer_active
)
2167 cfs_b
->timer_active
= 1;
2168 start_bandwidth_timer(&cfs_b
->period_timer
, cfs_b
->period
);
2171 static void destroy_cfs_bandwidth(struct cfs_bandwidth
*cfs_b
)
2173 hrtimer_cancel(&cfs_b
->period_timer
);
2174 hrtimer_cancel(&cfs_b
->slack_timer
);
2177 static void unthrottle_offline_cfs_rqs(struct rq
*rq
)
2179 struct cfs_rq
*cfs_rq
;
2181 for_each_leaf_cfs_rq(rq
, cfs_rq
) {
2182 struct cfs_bandwidth
*cfs_b
= tg_cfs_bandwidth(cfs_rq
->tg
);
2184 if (!cfs_rq
->runtime_enabled
)
2188 * clock_task is not advancing so we just need to make sure
2189 * there's some valid quota amount
2191 cfs_rq
->runtime_remaining
= cfs_b
->quota
;
2192 if (cfs_rq_throttled(cfs_rq
))
2193 unthrottle_cfs_rq(cfs_rq
);
2197 #else /* CONFIG_CFS_BANDWIDTH */
2198 static __always_inline
2199 void account_cfs_rq_runtime(struct cfs_rq
*cfs_rq
, unsigned long delta_exec
) {}
2200 static void check_cfs_rq_runtime(struct cfs_rq
*cfs_rq
) {}
2201 static void check_enqueue_throttle(struct cfs_rq
*cfs_rq
) {}
2202 static __always_inline
void return_cfs_rq_runtime(struct cfs_rq
*cfs_rq
) {}
2204 static inline int cfs_rq_throttled(struct cfs_rq
*cfs_rq
)
2209 static inline int throttled_hierarchy(struct cfs_rq
*cfs_rq
)
2214 static inline int throttled_lb_pair(struct task_group
*tg
,
2215 int src_cpu
, int dest_cpu
)
2220 void init_cfs_bandwidth(struct cfs_bandwidth
*cfs_b
) {}
2222 #ifdef CONFIG_FAIR_GROUP_SCHED
2223 static void init_cfs_rq_runtime(struct cfs_rq
*cfs_rq
) {}
2226 static inline struct cfs_bandwidth
*tg_cfs_bandwidth(struct task_group
*tg
)
2230 static inline void destroy_cfs_bandwidth(struct cfs_bandwidth
*cfs_b
) {}
2231 static inline void unthrottle_offline_cfs_rqs(struct rq
*rq
) {}
2233 #endif /* CONFIG_CFS_BANDWIDTH */
2235 /**************************************************
2236 * CFS operations on tasks:
2239 #ifdef CONFIG_SCHED_HRTICK
2240 static void hrtick_start_fair(struct rq
*rq
, struct task_struct
*p
)
2242 struct sched_entity
*se
= &p
->se
;
2243 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
2245 WARN_ON(task_rq(p
) != rq
);
2247 if (cfs_rq
->nr_running
> 1) {
2248 u64 slice
= sched_slice(cfs_rq
, se
);
2249 u64 ran
= se
->sum_exec_runtime
- se
->prev_sum_exec_runtime
;
2250 s64 delta
= slice
- ran
;
2259 * Don't schedule slices shorter than 10000ns, that just
2260 * doesn't make sense. Rely on vruntime for fairness.
2263 delta
= max_t(s64
, 10000LL, delta
);
2265 hrtick_start(rq
, delta
);
2270 * called from enqueue/dequeue and updates the hrtick when the
2271 * current task is from our class and nr_running is low enough
2274 static void hrtick_update(struct rq
*rq
)
2276 struct task_struct
*curr
= rq
->curr
;
2278 if (!hrtick_enabled(rq
) || curr
->sched_class
!= &fair_sched_class
)
2281 if (cfs_rq_of(&curr
->se
)->nr_running
< sched_nr_latency
)
2282 hrtick_start_fair(rq
, curr
);
2284 #else /* !CONFIG_SCHED_HRTICK */
2286 hrtick_start_fair(struct rq
*rq
, struct task_struct
*p
)
2290 static inline void hrtick_update(struct rq
*rq
)
2296 * The enqueue_task method is called before nr_running is
2297 * increased. Here we update the fair scheduling stats and
2298 * then put the task into the rbtree:
2301 enqueue_task_fair(struct rq
*rq
, struct task_struct
*p
, int flags
)
2303 struct cfs_rq
*cfs_rq
;
2304 struct sched_entity
*se
= &p
->se
;
2306 for_each_sched_entity(se
) {
2309 cfs_rq
= cfs_rq_of(se
);
2310 enqueue_entity(cfs_rq
, se
, flags
);
2313 * end evaluation on encountering a throttled cfs_rq
2315 * note: in the case of encountering a throttled cfs_rq we will
2316 * post the final h_nr_running increment below.
2318 if (cfs_rq_throttled(cfs_rq
))
2320 cfs_rq
->h_nr_running
++;
2322 flags
= ENQUEUE_WAKEUP
;
2325 for_each_sched_entity(se
) {
2326 cfs_rq
= cfs_rq_of(se
);
2327 cfs_rq
->h_nr_running
++;
2329 if (cfs_rq_throttled(cfs_rq
))
2332 update_cfs_load(cfs_rq
, 0);
2333 update_cfs_shares(cfs_rq
);
2341 static void set_next_buddy(struct sched_entity
*se
);
2344 * The dequeue_task method is called before nr_running is
2345 * decreased. We remove the task from the rbtree and
2346 * update the fair scheduling stats:
2348 static void dequeue_task_fair(struct rq
*rq
, struct task_struct
*p
, int flags
)
2350 struct cfs_rq
*cfs_rq
;
2351 struct sched_entity
*se
= &p
->se
;
2352 int task_sleep
= flags
& DEQUEUE_SLEEP
;
2354 for_each_sched_entity(se
) {
2355 cfs_rq
= cfs_rq_of(se
);
2356 dequeue_entity(cfs_rq
, se
, flags
);
2359 * end evaluation on encountering a throttled cfs_rq
2361 * note: in the case of encountering a throttled cfs_rq we will
2362 * post the final h_nr_running decrement below.
2364 if (cfs_rq_throttled(cfs_rq
))
2366 cfs_rq
->h_nr_running
--;
2368 /* Don't dequeue parent if it has other entities besides us */
2369 if (cfs_rq
->load
.weight
) {
2371 * Bias pick_next to pick a task from this cfs_rq, as
2372 * p is sleeping when it is within its sched_slice.
2374 if (task_sleep
&& parent_entity(se
))
2375 set_next_buddy(parent_entity(se
));
2377 /* avoid re-evaluating load for this entity */
2378 se
= parent_entity(se
);
2381 flags
|= DEQUEUE_SLEEP
;
2384 for_each_sched_entity(se
) {
2385 cfs_rq
= cfs_rq_of(se
);
2386 cfs_rq
->h_nr_running
--;
2388 if (cfs_rq_throttled(cfs_rq
))
2391 update_cfs_load(cfs_rq
, 0);
2392 update_cfs_shares(cfs_rq
);
2401 /* Used instead of source_load when we know the type == 0 */
2402 static unsigned long weighted_cpuload(const int cpu
)
2404 return cpu_rq(cpu
)->load
.weight
;
2408 * Return a low guess at the load of a migration-source cpu weighted
2409 * according to the scheduling class and "nice" value.
2411 * We want to under-estimate the load of migration sources, to
2412 * balance conservatively.
2414 static unsigned long source_load(int cpu
, int type
)
2416 struct rq
*rq
= cpu_rq(cpu
);
2417 unsigned long total
= weighted_cpuload(cpu
);
2419 if (type
== 0 || !sched_feat(LB_BIAS
))
2422 return min(rq
->cpu_load
[type
-1], total
);
2426 * Return a high guess at the load of a migration-target cpu weighted
2427 * according to the scheduling class and "nice" value.
2429 static unsigned long target_load(int cpu
, int type
)
2431 struct rq
*rq
= cpu_rq(cpu
);
2432 unsigned long total
= weighted_cpuload(cpu
);
2434 if (type
== 0 || !sched_feat(LB_BIAS
))
2437 return max(rq
->cpu_load
[type
-1], total
);
2440 static unsigned long power_of(int cpu
)
2442 return cpu_rq(cpu
)->cpu_power
;
2445 static unsigned long cpu_avg_load_per_task(int cpu
)
2447 struct rq
*rq
= cpu_rq(cpu
);
2448 unsigned long nr_running
= ACCESS_ONCE(rq
->nr_running
);
2451 return rq
->load
.weight
/ nr_running
;
2457 static void task_waking_fair(struct task_struct
*p
)
2459 struct sched_entity
*se
= &p
->se
;
2460 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
2463 #ifndef CONFIG_64BIT
2464 u64 min_vruntime_copy
;
2467 min_vruntime_copy
= cfs_rq
->min_vruntime_copy
;
2469 min_vruntime
= cfs_rq
->min_vruntime
;
2470 } while (min_vruntime
!= min_vruntime_copy
);
2472 min_vruntime
= cfs_rq
->min_vruntime
;
2475 se
->vruntime
-= min_vruntime
;
2478 #ifdef CONFIG_FAIR_GROUP_SCHED
2480 * effective_load() calculates the load change as seen from the root_task_group
2482 * Adding load to a group doesn't make a group heavier, but can cause movement
2483 * of group shares between cpus. Assuming the shares were perfectly aligned one
2484 * can calculate the shift in shares.
2486 * Calculate the effective load difference if @wl is added (subtracted) to @tg
2487 * on this @cpu and results in a total addition (subtraction) of @wg to the
2488 * total group weight.
2490 * Given a runqueue weight distribution (rw_i) we can compute a shares
2491 * distribution (s_i) using:
2493 * s_i = rw_i / \Sum rw_j (1)
2495 * Suppose we have 4 CPUs and our @tg is a direct child of the root group and
2496 * has 7 equal weight tasks, distributed as below (rw_i), with the resulting
2497 * shares distribution (s_i):
2499 * rw_i = { 2, 4, 1, 0 }
2500 * s_i = { 2/7, 4/7, 1/7, 0 }
2502 * As per wake_affine() we're interested in the load of two CPUs (the CPU the
2503 * task used to run on and the CPU the waker is running on), we need to
2504 * compute the effect of waking a task on either CPU and, in case of a sync
2505 * wakeup, compute the effect of the current task going to sleep.
2507 * So for a change of @wl to the local @cpu with an overall group weight change
2508 * of @wl we can compute the new shares distribution (s'_i) using:
2510 * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2)
2512 * Suppose we're interested in CPUs 0 and 1, and want to compute the load
2513 * differences in waking a task to CPU 0. The additional task changes the
2514 * weight and shares distributions like:
2516 * rw'_i = { 3, 4, 1, 0 }
2517 * s'_i = { 3/8, 4/8, 1/8, 0 }
2519 * We can then compute the difference in effective weight by using:
2521 * dw_i = S * (s'_i - s_i) (3)
2523 * Where 'S' is the group weight as seen by its parent.
2525 * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7)
2526 * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 -
2527 * 4/7) times the weight of the group.
2529 static long effective_load(struct task_group
*tg
, int cpu
, long wl
, long wg
)
2531 struct sched_entity
*se
= tg
->se
[cpu
];
2533 if (!tg
->parent
) /* the trivial, non-cgroup case */
2536 for_each_sched_entity(se
) {
2542 * W = @wg + \Sum rw_j
2544 W
= wg
+ calc_tg_weight(tg
, se
->my_q
);
2549 w
= se
->my_q
->load
.weight
+ wl
;
2552 * wl = S * s'_i; see (2)
2555 wl
= (w
* tg
->shares
) / W
;
2560 * Per the above, wl is the new se->load.weight value; since
2561 * those are clipped to [MIN_SHARES, ...) do so now. See
2562 * calc_cfs_shares().
2564 if (wl
< MIN_SHARES
)
2568 * wl = dw_i = S * (s'_i - s_i); see (3)
2570 wl
-= se
->load
.weight
;
2573 * Recursively apply this logic to all parent groups to compute
2574 * the final effective load change on the root group. Since
2575 * only the @tg group gets extra weight, all parent groups can
2576 * only redistribute existing shares. @wl is the shift in shares
2577 * resulting from this level per the above.
2586 static inline unsigned long effective_load(struct task_group
*tg
, int cpu
,
2587 unsigned long wl
, unsigned long wg
)
2594 static int wake_affine(struct sched_domain
*sd
, struct task_struct
*p
, int sync
)
2596 s64 this_load
, load
;
2597 int idx
, this_cpu
, prev_cpu
;
2598 unsigned long tl_per_task
;
2599 struct task_group
*tg
;
2600 unsigned long weight
;
2604 this_cpu
= smp_processor_id();
2605 prev_cpu
= task_cpu(p
);
2606 load
= source_load(prev_cpu
, idx
);
2607 this_load
= target_load(this_cpu
, idx
);
2610 * If sync wakeup then subtract the (maximum possible)
2611 * effect of the currently running task from the load
2612 * of the current CPU:
2615 tg
= task_group(current
);
2616 weight
= current
->se
.load
.weight
;
2618 this_load
+= effective_load(tg
, this_cpu
, -weight
, -weight
);
2619 load
+= effective_load(tg
, prev_cpu
, 0, -weight
);
2623 weight
= p
->se
.load
.weight
;
2626 * In low-load situations, where prev_cpu is idle and this_cpu is idle
2627 * due to the sync cause above having dropped this_load to 0, we'll
2628 * always have an imbalance, but there's really nothing you can do
2629 * about that, so that's good too.
2631 * Otherwise check if either cpus are near enough in load to allow this
2632 * task to be woken on this_cpu.
2634 if (this_load
> 0) {
2635 s64 this_eff_load
, prev_eff_load
;
2637 this_eff_load
= 100;
2638 this_eff_load
*= power_of(prev_cpu
);
2639 this_eff_load
*= this_load
+
2640 effective_load(tg
, this_cpu
, weight
, weight
);
2642 prev_eff_load
= 100 + (sd
->imbalance_pct
- 100) / 2;
2643 prev_eff_load
*= power_of(this_cpu
);
2644 prev_eff_load
*= load
+ effective_load(tg
, prev_cpu
, 0, weight
);
2646 balanced
= this_eff_load
<= prev_eff_load
;
2651 * If the currently running task will sleep within
2652 * a reasonable amount of time then attract this newly
2655 if (sync
&& balanced
)
2658 schedstat_inc(p
, se
.statistics
.nr_wakeups_affine_attempts
);
2659 tl_per_task
= cpu_avg_load_per_task(this_cpu
);
2662 (this_load
<= load
&&
2663 this_load
+ target_load(prev_cpu
, idx
) <= tl_per_task
)) {
2665 * This domain has SD_WAKE_AFFINE and
2666 * p is cache cold in this domain, and
2667 * there is no bad imbalance.
2669 schedstat_inc(sd
, ttwu_move_affine
);
2670 schedstat_inc(p
, se
.statistics
.nr_wakeups_affine
);
2678 * find_idlest_group finds and returns the least busy CPU group within the
2681 static struct sched_group
*
2682 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
,
2683 int this_cpu
, int load_idx
)
2685 struct sched_group
*idlest
= NULL
, *group
= sd
->groups
;
2686 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
2687 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
2690 unsigned long load
, avg_load
;
2694 /* Skip over this group if it has no CPUs allowed */
2695 if (!cpumask_intersects(sched_group_cpus(group
),
2696 tsk_cpus_allowed(p
)))
2699 local_group
= cpumask_test_cpu(this_cpu
,
2700 sched_group_cpus(group
));
2702 /* Tally up the load of all CPUs in the group */
2705 for_each_cpu(i
, sched_group_cpus(group
)) {
2706 /* Bias balancing toward cpus of our domain */
2708 load
= source_load(i
, load_idx
);
2710 load
= target_load(i
, load_idx
);
2715 /* Adjust by relative CPU power of the group */
2716 avg_load
= (avg_load
* SCHED_POWER_SCALE
) / group
->sgp
->power
;
2719 this_load
= avg_load
;
2720 } else if (avg_load
< min_load
) {
2721 min_load
= avg_load
;
2724 } while (group
= group
->next
, group
!= sd
->groups
);
2726 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
2732 * find_idlest_cpu - find the idlest cpu among the cpus in group.
2735 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
2737 unsigned long load
, min_load
= ULONG_MAX
;
2741 /* Traverse only the allowed CPUs */
2742 for_each_cpu_and(i
, sched_group_cpus(group
), tsk_cpus_allowed(p
)) {
2743 load
= weighted_cpuload(i
);
2745 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
2755 * Try and locate an idle CPU in the sched_domain.
2757 static int select_idle_sibling(struct task_struct
*p
, int target
)
2759 int cpu
= smp_processor_id();
2760 int prev_cpu
= task_cpu(p
);
2761 struct sched_domain
*sd
;
2762 struct sched_group
*sg
;
2766 * If the task is going to be woken-up on this cpu and if it is
2767 * already idle, then it is the right target.
2769 if (target
== cpu
&& idle_cpu(cpu
))
2773 * If the task is going to be woken-up on the cpu where it previously
2774 * ran and if it is currently idle, then it the right target.
2776 if (target
== prev_cpu
&& idle_cpu(prev_cpu
))
2780 * Otherwise, iterate the domains and find an elegible idle cpu.
2782 sd
= rcu_dereference(per_cpu(sd_llc
, target
));
2783 for_each_lower_domain(sd
) {
2786 if (!cpumask_intersects(sched_group_cpus(sg
),
2787 tsk_cpus_allowed(p
)))
2790 for_each_cpu(i
, sched_group_cpus(sg
)) {
2795 target
= cpumask_first_and(sched_group_cpus(sg
),
2796 tsk_cpus_allowed(p
));
2800 } while (sg
!= sd
->groups
);
2807 * sched_balance_self: balance the current task (running on cpu) in domains
2808 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
2811 * Balance, ie. select the least loaded group.
2813 * Returns the target CPU number, or the same CPU if no balancing is needed.
2815 * preempt must be disabled.
2818 select_task_rq_fair(struct task_struct
*p
, int sd_flag
, int wake_flags
)
2820 struct sched_domain
*tmp
, *affine_sd
= NULL
, *sd
= NULL
;
2821 int cpu
= smp_processor_id();
2822 int prev_cpu
= task_cpu(p
);
2824 int want_affine
= 0;
2825 int sync
= wake_flags
& WF_SYNC
;
2827 if (p
->nr_cpus_allowed
== 1)
2830 if (sd_flag
& SD_BALANCE_WAKE
) {
2831 if (cpumask_test_cpu(cpu
, tsk_cpus_allowed(p
)))
2837 for_each_domain(cpu
, tmp
) {
2838 if (!(tmp
->flags
& SD_LOAD_BALANCE
))
2842 * If both cpu and prev_cpu are part of this domain,
2843 * cpu is a valid SD_WAKE_AFFINE target.
2845 if (want_affine
&& (tmp
->flags
& SD_WAKE_AFFINE
) &&
2846 cpumask_test_cpu(prev_cpu
, sched_domain_span(tmp
))) {
2851 if (tmp
->flags
& sd_flag
)
2856 if (cpu
!= prev_cpu
&& wake_affine(affine_sd
, p
, sync
))
2859 new_cpu
= select_idle_sibling(p
, prev_cpu
);
2864 int load_idx
= sd
->forkexec_idx
;
2865 struct sched_group
*group
;
2868 if (!(sd
->flags
& sd_flag
)) {
2873 if (sd_flag
& SD_BALANCE_WAKE
)
2874 load_idx
= sd
->wake_idx
;
2876 group
= find_idlest_group(sd
, p
, cpu
, load_idx
);
2882 new_cpu
= find_idlest_cpu(group
, p
, cpu
);
2883 if (new_cpu
== -1 || new_cpu
== cpu
) {
2884 /* Now try balancing at a lower domain level of cpu */
2889 /* Now try balancing at a lower domain level of new_cpu */
2891 weight
= sd
->span_weight
;
2893 for_each_domain(cpu
, tmp
) {
2894 if (weight
<= tmp
->span_weight
)
2896 if (tmp
->flags
& sd_flag
)
2899 /* while loop will break here if sd == NULL */
2906 #endif /* CONFIG_SMP */
2908 static unsigned long
2909 wakeup_gran(struct sched_entity
*curr
, struct sched_entity
*se
)
2911 unsigned long gran
= sysctl_sched_wakeup_granularity
;
2914 * Since its curr running now, convert the gran from real-time
2915 * to virtual-time in his units.
2917 * By using 'se' instead of 'curr' we penalize light tasks, so
2918 * they get preempted easier. That is, if 'se' < 'curr' then
2919 * the resulting gran will be larger, therefore penalizing the
2920 * lighter, if otoh 'se' > 'curr' then the resulting gran will
2921 * be smaller, again penalizing the lighter task.
2923 * This is especially important for buddies when the leftmost
2924 * task is higher priority than the buddy.
2926 return calc_delta_fair(gran
, se
);
2930 * Should 'se' preempt 'curr'.
2944 wakeup_preempt_entity(struct sched_entity
*curr
, struct sched_entity
*se
)
2946 s64 gran
, vdiff
= curr
->vruntime
- se
->vruntime
;
2951 gran
= wakeup_gran(curr
, se
);
2958 static void set_last_buddy(struct sched_entity
*se
)
2960 if (entity_is_task(se
) && unlikely(task_of(se
)->policy
== SCHED_IDLE
))
2963 for_each_sched_entity(se
)
2964 cfs_rq_of(se
)->last
= se
;
2967 static void set_next_buddy(struct sched_entity
*se
)
2969 if (entity_is_task(se
) && unlikely(task_of(se
)->policy
== SCHED_IDLE
))
2972 for_each_sched_entity(se
)
2973 cfs_rq_of(se
)->next
= se
;
2976 static void set_skip_buddy(struct sched_entity
*se
)
2978 for_each_sched_entity(se
)
2979 cfs_rq_of(se
)->skip
= se
;
2983 * Preempt the current task with a newly woken task if needed:
2985 static void check_preempt_wakeup(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
2987 struct task_struct
*curr
= rq
->curr
;
2988 struct sched_entity
*se
= &curr
->se
, *pse
= &p
->se
;
2989 struct cfs_rq
*cfs_rq
= task_cfs_rq(curr
);
2990 int scale
= cfs_rq
->nr_running
>= sched_nr_latency
;
2991 int next_buddy_marked
= 0;
2993 if (unlikely(se
== pse
))
2997 * This is possible from callers such as move_task(), in which we
2998 * unconditionally check_prempt_curr() after an enqueue (which may have
2999 * lead to a throttle). This both saves work and prevents false
3000 * next-buddy nomination below.
3002 if (unlikely(throttled_hierarchy(cfs_rq_of(pse
))))
3005 if (sched_feat(NEXT_BUDDY
) && scale
&& !(wake_flags
& WF_FORK
)) {
3006 set_next_buddy(pse
);
3007 next_buddy_marked
= 1;
3011 * We can come here with TIF_NEED_RESCHED already set from new task
3014 * Note: this also catches the edge-case of curr being in a throttled
3015 * group (e.g. via set_curr_task), since update_curr() (in the
3016 * enqueue of curr) will have resulted in resched being set. This
3017 * prevents us from potentially nominating it as a false LAST_BUDDY
3020 if (test_tsk_need_resched(curr
))
3023 /* Idle tasks are by definition preempted by non-idle tasks. */
3024 if (unlikely(curr
->policy
== SCHED_IDLE
) &&
3025 likely(p
->policy
!= SCHED_IDLE
))
3029 * Batch and idle tasks do not preempt non-idle tasks (their preemption
3030 * is driven by the tick):
3032 if (unlikely(p
->policy
!= SCHED_NORMAL
))
3035 find_matching_se(&se
, &pse
);
3036 update_curr(cfs_rq_of(se
));
3038 if (wakeup_preempt_entity(se
, pse
) == 1) {
3040 * Bias pick_next to pick the sched entity that is
3041 * triggering this preemption.
3043 if (!next_buddy_marked
)
3044 set_next_buddy(pse
);
3053 * Only set the backward buddy when the current task is still
3054 * on the rq. This can happen when a wakeup gets interleaved
3055 * with schedule on the ->pre_schedule() or idle_balance()
3056 * point, either of which can * drop the rq lock.
3058 * Also, during early boot the idle thread is in the fair class,
3059 * for obvious reasons its a bad idea to schedule back to it.
3061 if (unlikely(!se
->on_rq
|| curr
== rq
->idle
))
3064 if (sched_feat(LAST_BUDDY
) && scale
&& entity_is_task(se
))
3068 static struct task_struct
*pick_next_task_fair(struct rq
*rq
)
3070 struct task_struct
*p
;
3071 struct cfs_rq
*cfs_rq
= &rq
->cfs
;
3072 struct sched_entity
*se
;
3074 if (!cfs_rq
->nr_running
)
3078 se
= pick_next_entity(cfs_rq
);
3079 set_next_entity(cfs_rq
, se
);
3080 cfs_rq
= group_cfs_rq(se
);
3084 if (hrtick_enabled(rq
))
3085 hrtick_start_fair(rq
, p
);
3091 * Account for a descheduled task:
3093 static void put_prev_task_fair(struct rq
*rq
, struct task_struct
*prev
)
3095 struct sched_entity
*se
= &prev
->se
;
3096 struct cfs_rq
*cfs_rq
;
3098 for_each_sched_entity(se
) {
3099 cfs_rq
= cfs_rq_of(se
);
3100 put_prev_entity(cfs_rq
, se
);
3105 * sched_yield() is very simple
3107 * The magic of dealing with the ->skip buddy is in pick_next_entity.
3109 static void yield_task_fair(struct rq
*rq
)
3111 struct task_struct
*curr
= rq
->curr
;
3112 struct cfs_rq
*cfs_rq
= task_cfs_rq(curr
);
3113 struct sched_entity
*se
= &curr
->se
;
3116 * Are we the only task in the tree?
3118 if (unlikely(rq
->nr_running
== 1))
3121 clear_buddies(cfs_rq
, se
);
3123 if (curr
->policy
!= SCHED_BATCH
) {
3124 update_rq_clock(rq
);
3126 * Update run-time statistics of the 'current'.
3128 update_curr(cfs_rq
);
3130 * Tell update_rq_clock() that we've just updated,
3131 * so we don't do microscopic update in schedule()
3132 * and double the fastpath cost.
3134 rq
->skip_clock_update
= 1;
3140 static bool yield_to_task_fair(struct rq
*rq
, struct task_struct
*p
, bool preempt
)
3142 struct sched_entity
*se
= &p
->se
;
3144 /* throttled hierarchies are not runnable */
3145 if (!se
->on_rq
|| throttled_hierarchy(cfs_rq_of(se
)))
3148 /* Tell the scheduler that we'd really like pse to run next. */
3151 yield_task_fair(rq
);
3157 /**************************************************
3158 * Fair scheduling class load-balancing methods:
3161 static unsigned long __read_mostly max_load_balance_interval
= HZ
/10;
3163 #define LBF_ALL_PINNED 0x01
3164 #define LBF_NEED_BREAK 0x02
3165 #define LBF_SOME_PINNED 0x04
3168 struct sched_domain
*sd
;
3176 struct cpumask
*dst_grpmask
;
3178 enum cpu_idle_type idle
;
3180 /* The set of CPUs under consideration for load-balancing */
3181 struct cpumask
*cpus
;
3186 unsigned int loop_break
;
3187 unsigned int loop_max
;
3191 * move_task - move a task from one runqueue to another runqueue.
3192 * Both runqueues must be locked.
3194 static void move_task(struct task_struct
*p
, struct lb_env
*env
)
3196 deactivate_task(env
->src_rq
, p
, 0);
3197 set_task_cpu(p
, env
->dst_cpu
);
3198 activate_task(env
->dst_rq
, p
, 0);
3199 check_preempt_curr(env
->dst_rq
, p
, 0);
3203 * Is this task likely cache-hot:
3206 task_hot(struct task_struct
*p
, u64 now
, struct sched_domain
*sd
)
3210 if (p
->sched_class
!= &fair_sched_class
)
3213 if (unlikely(p
->policy
== SCHED_IDLE
))
3217 * Buddy candidates are cache hot:
3219 if (sched_feat(CACHE_HOT_BUDDY
) && this_rq()->nr_running
&&
3220 (&p
->se
== cfs_rq_of(&p
->se
)->next
||
3221 &p
->se
== cfs_rq_of(&p
->se
)->last
))
3224 if (sysctl_sched_migration_cost
== -1)
3226 if (sysctl_sched_migration_cost
== 0)
3229 delta
= now
- p
->se
.exec_start
;
3231 return delta
< (s64
)sysctl_sched_migration_cost
;
3235 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
3238 int can_migrate_task(struct task_struct
*p
, struct lb_env
*env
)
3240 int tsk_cache_hot
= 0;
3242 * We do not migrate tasks that are:
3243 * 1) running (obviously), or
3244 * 2) cannot be migrated to this CPU due to cpus_allowed, or
3245 * 3) are cache-hot on their current CPU.
3247 if (!cpumask_test_cpu(env
->dst_cpu
, tsk_cpus_allowed(p
))) {
3250 schedstat_inc(p
, se
.statistics
.nr_failed_migrations_affine
);
3253 * Remember if this task can be migrated to any other cpu in
3254 * our sched_group. We may want to revisit it if we couldn't
3255 * meet load balance goals by pulling other tasks on src_cpu.
3257 * Also avoid computing new_dst_cpu if we have already computed
3258 * one in current iteration.
3260 if (!env
->dst_grpmask
|| (env
->flags
& LBF_SOME_PINNED
))
3263 new_dst_cpu
= cpumask_first_and(env
->dst_grpmask
,
3264 tsk_cpus_allowed(p
));
3265 if (new_dst_cpu
< nr_cpu_ids
) {
3266 env
->flags
|= LBF_SOME_PINNED
;
3267 env
->new_dst_cpu
= new_dst_cpu
;
3272 /* Record that we found atleast one task that could run on dst_cpu */
3273 env
->flags
&= ~LBF_ALL_PINNED
;
3275 if (task_running(env
->src_rq
, p
)) {
3276 schedstat_inc(p
, se
.statistics
.nr_failed_migrations_running
);
3281 * Aggressive migration if:
3282 * 1) task is cache cold, or
3283 * 2) too many balance attempts have failed.
3286 tsk_cache_hot
= task_hot(p
, env
->src_rq
->clock_task
, env
->sd
);
3287 if (!tsk_cache_hot
||
3288 env
->sd
->nr_balance_failed
> env
->sd
->cache_nice_tries
) {
3289 #ifdef CONFIG_SCHEDSTATS
3290 if (tsk_cache_hot
) {
3291 schedstat_inc(env
->sd
, lb_hot_gained
[env
->idle
]);
3292 schedstat_inc(p
, se
.statistics
.nr_forced_migrations
);
3298 if (tsk_cache_hot
) {
3299 schedstat_inc(p
, se
.statistics
.nr_failed_migrations_hot
);
3306 * move_one_task tries to move exactly one task from busiest to this_rq, as
3307 * part of active balancing operations within "domain".
3308 * Returns 1 if successful and 0 otherwise.
3310 * Called with both runqueues locked.
3312 static int move_one_task(struct lb_env
*env
)
3314 struct task_struct
*p
, *n
;
3316 list_for_each_entry_safe(p
, n
, &env
->src_rq
->cfs_tasks
, se
.group_node
) {
3317 if (throttled_lb_pair(task_group(p
), env
->src_rq
->cpu
, env
->dst_cpu
))
3320 if (!can_migrate_task(p
, env
))
3325 * Right now, this is only the second place move_task()
3326 * is called, so we can safely collect move_task()
3327 * stats here rather than inside move_task().
3329 schedstat_inc(env
->sd
, lb_gained
[env
->idle
]);
3335 static unsigned long task_h_load(struct task_struct
*p
);
3337 static const unsigned int sched_nr_migrate_break
= 32;
3340 * move_tasks tries to move up to imbalance weighted load from busiest to
3341 * this_rq, as part of a balancing operation within domain "sd".
3342 * Returns 1 if successful and 0 otherwise.
3344 * Called with both runqueues locked.
3346 static int move_tasks(struct lb_env
*env
)
3348 struct list_head
*tasks
= &env
->src_rq
->cfs_tasks
;
3349 struct task_struct
*p
;
3353 if (env
->imbalance
<= 0)
3356 while (!list_empty(tasks
)) {
3357 p
= list_first_entry(tasks
, struct task_struct
, se
.group_node
);
3360 /* We've more or less seen every task there is, call it quits */
3361 if (env
->loop
> env
->loop_max
)
3364 /* take a breather every nr_migrate tasks */
3365 if (env
->loop
> env
->loop_break
) {
3366 env
->loop_break
+= sched_nr_migrate_break
;
3367 env
->flags
|= LBF_NEED_BREAK
;
3371 if (throttled_lb_pair(task_group(p
), env
->src_cpu
, env
->dst_cpu
))
3374 load
= task_h_load(p
);
3376 if (sched_feat(LB_MIN
) && load
< 16 && !env
->sd
->nr_balance_failed
)
3379 if ((load
/ 2) > env
->imbalance
)
3382 if (!can_migrate_task(p
, env
))
3387 env
->imbalance
-= load
;
3389 #ifdef CONFIG_PREEMPT
3391 * NEWIDLE balancing is a source of latency, so preemptible
3392 * kernels will stop after the first task is pulled to minimize
3393 * the critical section.
3395 if (env
->idle
== CPU_NEWLY_IDLE
)
3400 * We only want to steal up to the prescribed amount of
3403 if (env
->imbalance
<= 0)
3408 list_move_tail(&p
->se
.group_node
, tasks
);
3412 * Right now, this is one of only two places move_task() is called,
3413 * so we can safely collect move_task() stats here rather than
3414 * inside move_task().
3416 schedstat_add(env
->sd
, lb_gained
[env
->idle
], pulled
);
3421 #ifdef CONFIG_FAIR_GROUP_SCHED
3423 * update tg->load_weight by folding this cpu's load_avg
3425 static int update_shares_cpu(struct task_group
*tg
, int cpu
)
3427 struct cfs_rq
*cfs_rq
;
3428 unsigned long flags
;
3435 cfs_rq
= tg
->cfs_rq
[cpu
];
3437 raw_spin_lock_irqsave(&rq
->lock
, flags
);
3439 update_rq_clock(rq
);
3440 update_cfs_load(cfs_rq
, 1);
3443 * We need to update shares after updating tg->load_weight in
3444 * order to adjust the weight of groups with long running tasks.
3446 update_cfs_shares(cfs_rq
);
3448 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
3453 static void update_shares(int cpu
)
3455 struct cfs_rq
*cfs_rq
;
3456 struct rq
*rq
= cpu_rq(cpu
);
3460 * Iterates the task_group tree in a bottom up fashion, see
3461 * list_add_leaf_cfs_rq() for details.
3463 for_each_leaf_cfs_rq(rq
, cfs_rq
) {
3464 /* throttled entities do not contribute to load */
3465 if (throttled_hierarchy(cfs_rq
))
3468 update_shares_cpu(cfs_rq
->tg
, cpu
);
3474 * Compute the cpu's hierarchical load factor for each task group.
3475 * This needs to be done in a top-down fashion because the load of a child
3476 * group is a fraction of its parents load.
3478 static int tg_load_down(struct task_group
*tg
, void *data
)
3481 long cpu
= (long)data
;
3484 load
= cpu_rq(cpu
)->load
.weight
;
3486 load
= tg
->parent
->cfs_rq
[cpu
]->h_load
;
3487 load
*= tg
->se
[cpu
]->load
.weight
;
3488 load
/= tg
->parent
->cfs_rq
[cpu
]->load
.weight
+ 1;
3491 tg
->cfs_rq
[cpu
]->h_load
= load
;
3496 static void update_h_load(long cpu
)
3498 struct rq
*rq
= cpu_rq(cpu
);
3499 unsigned long now
= jiffies
;
3501 if (rq
->h_load_throttle
== now
)
3504 rq
->h_load_throttle
= now
;
3507 walk_tg_tree(tg_load_down
, tg_nop
, (void *)cpu
);
3511 static unsigned long task_h_load(struct task_struct
*p
)
3513 struct cfs_rq
*cfs_rq
= task_cfs_rq(p
);
3516 load
= p
->se
.load
.weight
;
3517 load
= div_u64(load
* cfs_rq
->h_load
, cfs_rq
->load
.weight
+ 1);
3522 static inline void update_shares(int cpu
)
3526 static inline void update_h_load(long cpu
)
3530 static unsigned long task_h_load(struct task_struct
*p
)
3532 return p
->se
.load
.weight
;
3536 /********** Helpers for find_busiest_group ************************/
3538 * sd_lb_stats - Structure to store the statistics of a sched_domain
3539 * during load balancing.
3541 struct sd_lb_stats
{
3542 struct sched_group
*busiest
; /* Busiest group in this sd */
3543 struct sched_group
*this; /* Local group in this sd */
3544 unsigned long total_load
; /* Total load of all groups in sd */
3545 unsigned long total_pwr
; /* Total power of all groups in sd */
3546 unsigned long avg_load
; /* Average load across all groups in sd */
3548 /** Statistics of this group */
3549 unsigned long this_load
;
3550 unsigned long this_load_per_task
;
3551 unsigned long this_nr_running
;
3552 unsigned long this_has_capacity
;
3553 unsigned int this_idle_cpus
;
3555 /* Statistics of the busiest group */
3556 unsigned int busiest_idle_cpus
;
3557 unsigned long max_load
;
3558 unsigned long busiest_load_per_task
;
3559 unsigned long busiest_nr_running
;
3560 unsigned long busiest_group_capacity
;
3561 unsigned long busiest_has_capacity
;
3562 unsigned int busiest_group_weight
;
3564 int group_imb
; /* Is there imbalance in this sd */
3568 * sg_lb_stats - stats of a sched_group required for load_balancing
3570 struct sg_lb_stats
{
3571 unsigned long avg_load
; /*Avg load across the CPUs of the group */
3572 unsigned long group_load
; /* Total load over the CPUs of the group */
3573 unsigned long sum_nr_running
; /* Nr tasks running in the group */
3574 unsigned long sum_weighted_load
; /* Weighted load of group's tasks */
3575 unsigned long group_capacity
;
3576 unsigned long idle_cpus
;
3577 unsigned long group_weight
;
3578 int group_imb
; /* Is there an imbalance in the group ? */
3579 int group_has_capacity
; /* Is there extra capacity in the group? */
3583 * get_sd_load_idx - Obtain the load index for a given sched domain.
3584 * @sd: The sched_domain whose load_idx is to be obtained.
3585 * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
3587 static inline int get_sd_load_idx(struct sched_domain
*sd
,
3588 enum cpu_idle_type idle
)
3594 load_idx
= sd
->busy_idx
;
3597 case CPU_NEWLY_IDLE
:
3598 load_idx
= sd
->newidle_idx
;
3601 load_idx
= sd
->idle_idx
;
3608 unsigned long default_scale_freq_power(struct sched_domain
*sd
, int cpu
)
3610 return SCHED_POWER_SCALE
;
3613 unsigned long __weak
arch_scale_freq_power(struct sched_domain
*sd
, int cpu
)
3615 return default_scale_freq_power(sd
, cpu
);
3618 unsigned long default_scale_smt_power(struct sched_domain
*sd
, int cpu
)
3620 unsigned long weight
= sd
->span_weight
;
3621 unsigned long smt_gain
= sd
->smt_gain
;
3628 unsigned long __weak
arch_scale_smt_power(struct sched_domain
*sd
, int cpu
)
3630 return default_scale_smt_power(sd
, cpu
);
3633 unsigned long scale_rt_power(int cpu
)
3635 struct rq
*rq
= cpu_rq(cpu
);
3636 u64 total
, available
, age_stamp
, avg
;
3639 * Since we're reading these variables without serialization make sure
3640 * we read them once before doing sanity checks on them.
3642 age_stamp
= ACCESS_ONCE(rq
->age_stamp
);
3643 avg
= ACCESS_ONCE(rq
->rt_avg
);
3645 total
= sched_avg_period() + (rq
->clock
- age_stamp
);
3647 if (unlikely(total
< avg
)) {
3648 /* Ensures that power won't end up being negative */
3651 available
= total
- avg
;
3654 if (unlikely((s64
)total
< SCHED_POWER_SCALE
))
3655 total
= SCHED_POWER_SCALE
;
3657 total
>>= SCHED_POWER_SHIFT
;
3659 return div_u64(available
, total
);
3662 static void update_cpu_power(struct sched_domain
*sd
, int cpu
)
3664 unsigned long weight
= sd
->span_weight
;
3665 unsigned long power
= SCHED_POWER_SCALE
;
3666 struct sched_group
*sdg
= sd
->groups
;
3668 if ((sd
->flags
& SD_SHARE_CPUPOWER
) && weight
> 1) {
3669 if (sched_feat(ARCH_POWER
))
3670 power
*= arch_scale_smt_power(sd
, cpu
);
3672 power
*= default_scale_smt_power(sd
, cpu
);
3674 power
>>= SCHED_POWER_SHIFT
;
3677 sdg
->sgp
->power_orig
= power
;
3679 if (sched_feat(ARCH_POWER
))
3680 power
*= arch_scale_freq_power(sd
, cpu
);
3682 power
*= default_scale_freq_power(sd
, cpu
);
3684 power
>>= SCHED_POWER_SHIFT
;
3686 power
*= scale_rt_power(cpu
);
3687 power
>>= SCHED_POWER_SHIFT
;
3692 cpu_rq(cpu
)->cpu_power
= power
;
3693 sdg
->sgp
->power
= power
;
3696 void update_group_power(struct sched_domain
*sd
, int cpu
)
3698 struct sched_domain
*child
= sd
->child
;
3699 struct sched_group
*group
, *sdg
= sd
->groups
;
3700 unsigned long power
;
3701 unsigned long interval
;
3703 interval
= msecs_to_jiffies(sd
->balance_interval
);
3704 interval
= clamp(interval
, 1UL, max_load_balance_interval
);
3705 sdg
->sgp
->next_update
= jiffies
+ interval
;
3708 update_cpu_power(sd
, cpu
);
3714 if (child
->flags
& SD_OVERLAP
) {
3716 * SD_OVERLAP domains cannot assume that child groups
3717 * span the current group.
3720 for_each_cpu(cpu
, sched_group_cpus(sdg
))
3721 power
+= power_of(cpu
);
3724 * !SD_OVERLAP domains can assume that child groups
3725 * span the current group.
3728 group
= child
->groups
;
3730 power
+= group
->sgp
->power
;
3731 group
= group
->next
;
3732 } while (group
!= child
->groups
);
3735 sdg
->sgp
->power_orig
= sdg
->sgp
->power
= power
;
3739 * Try and fix up capacity for tiny siblings, this is needed when
3740 * things like SD_ASYM_PACKING need f_b_g to select another sibling
3741 * which on its own isn't powerful enough.
3743 * See update_sd_pick_busiest() and check_asym_packing().
3746 fix_small_capacity(struct sched_domain
*sd
, struct sched_group
*group
)
3749 * Only siblings can have significantly less than SCHED_POWER_SCALE
3751 if (!(sd
->flags
& SD_SHARE_CPUPOWER
))
3755 * If ~90% of the cpu_power is still there, we're good.
3757 if (group
->sgp
->power
* 32 > group
->sgp
->power_orig
* 29)
3764 * update_sg_lb_stats - Update sched_group's statistics for load balancing.
3765 * @env: The load balancing environment.
3766 * @group: sched_group whose statistics are to be updated.
3767 * @load_idx: Load index of sched_domain of this_cpu for load calc.
3768 * @local_group: Does group contain this_cpu.
3769 * @balance: Should we balance.
3770 * @sgs: variable to hold the statistics for this group.
3772 static inline void update_sg_lb_stats(struct lb_env
*env
,
3773 struct sched_group
*group
, int load_idx
,
3774 int local_group
, int *balance
, struct sg_lb_stats
*sgs
)
3776 unsigned long nr_running
, max_nr_running
, min_nr_running
;
3777 unsigned long load
, max_cpu_load
, min_cpu_load
;
3778 unsigned int balance_cpu
= -1, first_idle_cpu
= 0;
3779 unsigned long avg_load_per_task
= 0;
3783 balance_cpu
= group_balance_cpu(group
);
3785 /* Tally up the load of all CPUs in the group */
3787 min_cpu_load
= ~0UL;
3789 min_nr_running
= ~0UL;
3791 for_each_cpu_and(i
, sched_group_cpus(group
), env
->cpus
) {
3792 struct rq
*rq
= cpu_rq(i
);
3794 nr_running
= rq
->nr_running
;
3796 /* Bias balancing toward cpus of our domain */
3798 if (idle_cpu(i
) && !first_idle_cpu
&&
3799 cpumask_test_cpu(i
, sched_group_mask(group
))) {
3804 load
= target_load(i
, load_idx
);
3806 load
= source_load(i
, load_idx
);
3807 if (load
> max_cpu_load
)
3808 max_cpu_load
= load
;
3809 if (min_cpu_load
> load
)
3810 min_cpu_load
= load
;
3812 if (nr_running
> max_nr_running
)
3813 max_nr_running
= nr_running
;
3814 if (min_nr_running
> nr_running
)
3815 min_nr_running
= nr_running
;
3818 sgs
->group_load
+= load
;
3819 sgs
->sum_nr_running
+= nr_running
;
3820 sgs
->sum_weighted_load
+= weighted_cpuload(i
);
3826 * First idle cpu or the first cpu(busiest) in this sched group
3827 * is eligible for doing load balancing at this and above
3828 * domains. In the newly idle case, we will allow all the cpu's
3829 * to do the newly idle load balance.
3832 if (env
->idle
!= CPU_NEWLY_IDLE
) {
3833 if (balance_cpu
!= env
->dst_cpu
) {
3837 update_group_power(env
->sd
, env
->dst_cpu
);
3838 } else if (time_after_eq(jiffies
, group
->sgp
->next_update
))
3839 update_group_power(env
->sd
, env
->dst_cpu
);
3842 /* Adjust by relative CPU power of the group */
3843 sgs
->avg_load
= (sgs
->group_load
*SCHED_POWER_SCALE
) / group
->sgp
->power
;
3846 * Consider the group unbalanced when the imbalance is larger
3847 * than the average weight of a task.
3849 * APZ: with cgroup the avg task weight can vary wildly and
3850 * might not be a suitable number - should we keep a
3851 * normalized nr_running number somewhere that negates
3854 if (sgs
->sum_nr_running
)
3855 avg_load_per_task
= sgs
->sum_weighted_load
/ sgs
->sum_nr_running
;
3857 if ((max_cpu_load
- min_cpu_load
) >= avg_load_per_task
&&
3858 (max_nr_running
- min_nr_running
) > 1)
3861 sgs
->group_capacity
= DIV_ROUND_CLOSEST(group
->sgp
->power
,
3863 if (!sgs
->group_capacity
)
3864 sgs
->group_capacity
= fix_small_capacity(env
->sd
, group
);
3865 sgs
->group_weight
= group
->group_weight
;
3867 if (sgs
->group_capacity
> sgs
->sum_nr_running
)
3868 sgs
->group_has_capacity
= 1;
3872 * update_sd_pick_busiest - return 1 on busiest group
3873 * @env: The load balancing environment.
3874 * @sds: sched_domain statistics
3875 * @sg: sched_group candidate to be checked for being the busiest
3876 * @sgs: sched_group statistics
3878 * Determine if @sg is a busier group than the previously selected
3881 static bool update_sd_pick_busiest(struct lb_env
*env
,
3882 struct sd_lb_stats
*sds
,
3883 struct sched_group
*sg
,
3884 struct sg_lb_stats
*sgs
)
3886 if (sgs
->avg_load
<= sds
->max_load
)
3889 if (sgs
->sum_nr_running
> sgs
->group_capacity
)
3896 * ASYM_PACKING needs to move all the work to the lowest
3897 * numbered CPUs in the group, therefore mark all groups
3898 * higher than ourself as busy.
3900 if ((env
->sd
->flags
& SD_ASYM_PACKING
) && sgs
->sum_nr_running
&&
3901 env
->dst_cpu
< group_first_cpu(sg
)) {
3905 if (group_first_cpu(sds
->busiest
) > group_first_cpu(sg
))
3913 * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
3914 * @env: The load balancing environment.
3915 * @balance: Should we balance.
3916 * @sds: variable to hold the statistics for this sched_domain.
3918 static inline void update_sd_lb_stats(struct lb_env
*env
,
3919 int *balance
, struct sd_lb_stats
*sds
)
3921 struct sched_domain
*child
= env
->sd
->child
;
3922 struct sched_group
*sg
= env
->sd
->groups
;
3923 struct sg_lb_stats sgs
;
3924 int load_idx
, prefer_sibling
= 0;
3926 if (child
&& child
->flags
& SD_PREFER_SIBLING
)
3929 load_idx
= get_sd_load_idx(env
->sd
, env
->idle
);
3934 local_group
= cpumask_test_cpu(env
->dst_cpu
, sched_group_cpus(sg
));
3935 memset(&sgs
, 0, sizeof(sgs
));
3936 update_sg_lb_stats(env
, sg
, load_idx
, local_group
, balance
, &sgs
);
3938 if (local_group
&& !(*balance
))
3941 sds
->total_load
+= sgs
.group_load
;
3942 sds
->total_pwr
+= sg
->sgp
->power
;
3945 * In case the child domain prefers tasks go to siblings
3946 * first, lower the sg capacity to one so that we'll try
3947 * and move all the excess tasks away. We lower the capacity
3948 * of a group only if the local group has the capacity to fit
3949 * these excess tasks, i.e. nr_running < group_capacity. The
3950 * extra check prevents the case where you always pull from the
3951 * heaviest group when it is already under-utilized (possible
3952 * with a large weight task outweighs the tasks on the system).
3954 if (prefer_sibling
&& !local_group
&& sds
->this_has_capacity
)
3955 sgs
.group_capacity
= min(sgs
.group_capacity
, 1UL);
3958 sds
->this_load
= sgs
.avg_load
;
3960 sds
->this_nr_running
= sgs
.sum_nr_running
;
3961 sds
->this_load_per_task
= sgs
.sum_weighted_load
;
3962 sds
->this_has_capacity
= sgs
.group_has_capacity
;
3963 sds
->this_idle_cpus
= sgs
.idle_cpus
;
3964 } else if (update_sd_pick_busiest(env
, sds
, sg
, &sgs
)) {
3965 sds
->max_load
= sgs
.avg_load
;
3967 sds
->busiest_nr_running
= sgs
.sum_nr_running
;
3968 sds
->busiest_idle_cpus
= sgs
.idle_cpus
;
3969 sds
->busiest_group_capacity
= sgs
.group_capacity
;
3970 sds
->busiest_load_per_task
= sgs
.sum_weighted_load
;
3971 sds
->busiest_has_capacity
= sgs
.group_has_capacity
;
3972 sds
->busiest_group_weight
= sgs
.group_weight
;
3973 sds
->group_imb
= sgs
.group_imb
;
3977 } while (sg
!= env
->sd
->groups
);
3981 * check_asym_packing - Check to see if the group is packed into the
3984 * This is primarily intended to used at the sibling level. Some
3985 * cores like POWER7 prefer to use lower numbered SMT threads. In the
3986 * case of POWER7, it can move to lower SMT modes only when higher
3987 * threads are idle. When in lower SMT modes, the threads will
3988 * perform better since they share less core resources. Hence when we
3989 * have idle threads, we want them to be the higher ones.
3991 * This packing function is run on idle threads. It checks to see if
3992 * the busiest CPU in this domain (core in the P7 case) has a higher
3993 * CPU number than the packing function is being run on. Here we are
3994 * assuming lower CPU number will be equivalent to lower a SMT thread
3997 * Returns 1 when packing is required and a task should be moved to
3998 * this CPU. The amount of the imbalance is returned in *imbalance.
4000 * @env: The load balancing environment.
4001 * @sds: Statistics of the sched_domain which is to be packed
4003 static int check_asym_packing(struct lb_env
*env
, struct sd_lb_stats
*sds
)
4007 if (!(env
->sd
->flags
& SD_ASYM_PACKING
))
4013 busiest_cpu
= group_first_cpu(sds
->busiest
);
4014 if (env
->dst_cpu
> busiest_cpu
)
4017 env
->imbalance
= DIV_ROUND_CLOSEST(
4018 sds
->max_load
* sds
->busiest
->sgp
->power
, SCHED_POWER_SCALE
);
4024 * fix_small_imbalance - Calculate the minor imbalance that exists
4025 * amongst the groups of a sched_domain, during
4027 * @env: The load balancing environment.
4028 * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
4031 void fix_small_imbalance(struct lb_env
*env
, struct sd_lb_stats
*sds
)
4033 unsigned long tmp
, pwr_now
= 0, pwr_move
= 0;
4034 unsigned int imbn
= 2;
4035 unsigned long scaled_busy_load_per_task
;
4037 if (sds
->this_nr_running
) {
4038 sds
->this_load_per_task
/= sds
->this_nr_running
;
4039 if (sds
->busiest_load_per_task
>
4040 sds
->this_load_per_task
)
4043 sds
->this_load_per_task
=
4044 cpu_avg_load_per_task(env
->dst_cpu
);
4047 scaled_busy_load_per_task
= sds
->busiest_load_per_task
4048 * SCHED_POWER_SCALE
;
4049 scaled_busy_load_per_task
/= sds
->busiest
->sgp
->power
;
4051 if (sds
->max_load
- sds
->this_load
+ scaled_busy_load_per_task
>=
4052 (scaled_busy_load_per_task
* imbn
)) {
4053 env
->imbalance
= sds
->busiest_load_per_task
;
4058 * OK, we don't have enough imbalance to justify moving tasks,
4059 * however we may be able to increase total CPU power used by
4063 pwr_now
+= sds
->busiest
->sgp
->power
*
4064 min(sds
->busiest_load_per_task
, sds
->max_load
);
4065 pwr_now
+= sds
->this->sgp
->power
*
4066 min(sds
->this_load_per_task
, sds
->this_load
);
4067 pwr_now
/= SCHED_POWER_SCALE
;
4069 /* Amount of load we'd subtract */
4070 tmp
= (sds
->busiest_load_per_task
* SCHED_POWER_SCALE
) /
4071 sds
->busiest
->sgp
->power
;
4072 if (sds
->max_load
> tmp
)
4073 pwr_move
+= sds
->busiest
->sgp
->power
*
4074 min(sds
->busiest_load_per_task
, sds
->max_load
- tmp
);
4076 /* Amount of load we'd add */
4077 if (sds
->max_load
* sds
->busiest
->sgp
->power
<
4078 sds
->busiest_load_per_task
* SCHED_POWER_SCALE
)
4079 tmp
= (sds
->max_load
* sds
->busiest
->sgp
->power
) /
4080 sds
->this->sgp
->power
;
4082 tmp
= (sds
->busiest_load_per_task
* SCHED_POWER_SCALE
) /
4083 sds
->this->sgp
->power
;
4084 pwr_move
+= sds
->this->sgp
->power
*
4085 min(sds
->this_load_per_task
, sds
->this_load
+ tmp
);
4086 pwr_move
/= SCHED_POWER_SCALE
;
4088 /* Move if we gain throughput */
4089 if (pwr_move
> pwr_now
)
4090 env
->imbalance
= sds
->busiest_load_per_task
;
4094 * calculate_imbalance - Calculate the amount of imbalance present within the
4095 * groups of a given sched_domain during load balance.
4096 * @env: load balance environment
4097 * @sds: statistics of the sched_domain whose imbalance is to be calculated.
4099 static inline void calculate_imbalance(struct lb_env
*env
, struct sd_lb_stats
*sds
)
4101 unsigned long max_pull
, load_above_capacity
= ~0UL;
4103 sds
->busiest_load_per_task
/= sds
->busiest_nr_running
;
4104 if (sds
->group_imb
) {
4105 sds
->busiest_load_per_task
=
4106 min(sds
->busiest_load_per_task
, sds
->avg_load
);
4110 * In the presence of smp nice balancing, certain scenarios can have
4111 * max load less than avg load(as we skip the groups at or below
4112 * its cpu_power, while calculating max_load..)
4114 if (sds
->max_load
< sds
->avg_load
) {
4116 return fix_small_imbalance(env
, sds
);
4119 if (!sds
->group_imb
) {
4121 * Don't want to pull so many tasks that a group would go idle.
4123 load_above_capacity
= (sds
->busiest_nr_running
-
4124 sds
->busiest_group_capacity
);
4126 load_above_capacity
*= (SCHED_LOAD_SCALE
* SCHED_POWER_SCALE
);
4128 load_above_capacity
/= sds
->busiest
->sgp
->power
;
4132 * We're trying to get all the cpus to the average_load, so we don't
4133 * want to push ourselves above the average load, nor do we wish to
4134 * reduce the max loaded cpu below the average load. At the same time,
4135 * we also don't want to reduce the group load below the group capacity
4136 * (so that we can implement power-savings policies etc). Thus we look
4137 * for the minimum possible imbalance.
4138 * Be careful of negative numbers as they'll appear as very large values
4139 * with unsigned longs.
4141 max_pull
= min(sds
->max_load
- sds
->avg_load
, load_above_capacity
);
4143 /* How much load to actually move to equalise the imbalance */
4144 env
->imbalance
= min(max_pull
* sds
->busiest
->sgp
->power
,
4145 (sds
->avg_load
- sds
->this_load
) * sds
->this->sgp
->power
)
4146 / SCHED_POWER_SCALE
;
4149 * if *imbalance is less than the average load per runnable task
4150 * there is no guarantee that any tasks will be moved so we'll have
4151 * a think about bumping its value to force at least one task to be
4154 if (env
->imbalance
< sds
->busiest_load_per_task
)
4155 return fix_small_imbalance(env
, sds
);
4159 /******* find_busiest_group() helpers end here *********************/
4162 * find_busiest_group - Returns the busiest group within the sched_domain
4163 * if there is an imbalance. If there isn't an imbalance, and
4164 * the user has opted for power-savings, it returns a group whose
4165 * CPUs can be put to idle by rebalancing those tasks elsewhere, if
4166 * such a group exists.
4168 * Also calculates the amount of weighted load which should be moved
4169 * to restore balance.
4171 * @env: The load balancing environment.
4172 * @balance: Pointer to a variable indicating if this_cpu
4173 * is the appropriate cpu to perform load balancing at this_level.
4175 * Returns: - the busiest group if imbalance exists.
4176 * - If no imbalance and user has opted for power-savings balance,
4177 * return the least loaded group whose CPUs can be
4178 * put to idle by rebalancing its tasks onto our group.
4180 static struct sched_group
*
4181 find_busiest_group(struct lb_env
*env
, int *balance
)
4183 struct sd_lb_stats sds
;
4185 memset(&sds
, 0, sizeof(sds
));
4188 * Compute the various statistics relavent for load balancing at
4191 update_sd_lb_stats(env
, balance
, &sds
);
4194 * this_cpu is not the appropriate cpu to perform load balancing at
4200 if ((env
->idle
== CPU_IDLE
|| env
->idle
== CPU_NEWLY_IDLE
) &&
4201 check_asym_packing(env
, &sds
))
4204 /* There is no busy sibling group to pull tasks from */
4205 if (!sds
.busiest
|| sds
.busiest_nr_running
== 0)
4208 sds
.avg_load
= (SCHED_POWER_SCALE
* sds
.total_load
) / sds
.total_pwr
;
4211 * If the busiest group is imbalanced the below checks don't
4212 * work because they assumes all things are equal, which typically
4213 * isn't true due to cpus_allowed constraints and the like.
4218 /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
4219 if (env
->idle
== CPU_NEWLY_IDLE
&& sds
.this_has_capacity
&&
4220 !sds
.busiest_has_capacity
)
4224 * If the local group is more busy than the selected busiest group
4225 * don't try and pull any tasks.
4227 if (sds
.this_load
>= sds
.max_load
)
4231 * Don't pull any tasks if this group is already above the domain
4234 if (sds
.this_load
>= sds
.avg_load
)
4237 if (env
->idle
== CPU_IDLE
) {
4239 * This cpu is idle. If the busiest group load doesn't
4240 * have more tasks than the number of available cpu's and
4241 * there is no imbalance between this and busiest group
4242 * wrt to idle cpu's, it is balanced.
4244 if ((sds
.this_idle_cpus
<= sds
.busiest_idle_cpus
+ 1) &&
4245 sds
.busiest_nr_running
<= sds
.busiest_group_weight
)
4249 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
4250 * imbalance_pct to be conservative.
4252 if (100 * sds
.max_load
<= env
->sd
->imbalance_pct
* sds
.this_load
)
4257 /* Looks like there is an imbalance. Compute it */
4258 calculate_imbalance(env
, &sds
);
4268 * find_busiest_queue - find the busiest runqueue among the cpus in group.
4270 static struct rq
*find_busiest_queue(struct lb_env
*env
,
4271 struct sched_group
*group
)
4273 struct rq
*busiest
= NULL
, *rq
;
4274 unsigned long max_load
= 0;
4277 for_each_cpu(i
, sched_group_cpus(group
)) {
4278 unsigned long power
= power_of(i
);
4279 unsigned long capacity
= DIV_ROUND_CLOSEST(power
,
4284 capacity
= fix_small_capacity(env
->sd
, group
);
4286 if (!cpumask_test_cpu(i
, env
->cpus
))
4290 wl
= weighted_cpuload(i
);
4293 * When comparing with imbalance, use weighted_cpuload()
4294 * which is not scaled with the cpu power.
4296 if (capacity
&& rq
->nr_running
== 1 && wl
> env
->imbalance
)
4300 * For the load comparisons with the other cpu's, consider
4301 * the weighted_cpuload() scaled with the cpu power, so that
4302 * the load can be moved away from the cpu that is potentially
4303 * running at a lower capacity.
4305 wl
= (wl
* SCHED_POWER_SCALE
) / power
;
4307 if (wl
> max_load
) {
4317 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
4318 * so long as it is large enough.
4320 #define MAX_PINNED_INTERVAL 512
4322 /* Working cpumask for load_balance and load_balance_newidle. */
4323 DEFINE_PER_CPU(cpumask_var_t
, load_balance_tmpmask
);
4325 static int need_active_balance(struct lb_env
*env
)
4327 struct sched_domain
*sd
= env
->sd
;
4329 if (env
->idle
== CPU_NEWLY_IDLE
) {
4332 * ASYM_PACKING needs to force migrate tasks from busy but
4333 * higher numbered CPUs in order to pack all tasks in the
4334 * lowest numbered CPUs.
4336 if ((sd
->flags
& SD_ASYM_PACKING
) && env
->src_cpu
> env
->dst_cpu
)
4340 return unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2);
4343 static int active_load_balance_cpu_stop(void *data
);
4346 * Check this_cpu to ensure it is balanced within domain. Attempt to move
4347 * tasks if there is an imbalance.
4349 static int load_balance(int this_cpu
, struct rq
*this_rq
,
4350 struct sched_domain
*sd
, enum cpu_idle_type idle
,
4353 int ld_moved
, cur_ld_moved
, active_balance
= 0;
4354 int lb_iterations
, max_lb_iterations
;
4355 struct sched_group
*group
;
4357 unsigned long flags
;
4358 struct cpumask
*cpus
= __get_cpu_var(load_balance_tmpmask
);
4360 struct lb_env env
= {
4362 .dst_cpu
= this_cpu
,
4364 .dst_grpmask
= sched_group_cpus(sd
->groups
),
4366 .loop_break
= sched_nr_migrate_break
,
4370 cpumask_copy(cpus
, cpu_active_mask
);
4371 max_lb_iterations
= cpumask_weight(env
.dst_grpmask
);
4373 schedstat_inc(sd
, lb_count
[idle
]);
4376 group
= find_busiest_group(&env
, balance
);
4382 schedstat_inc(sd
, lb_nobusyg
[idle
]);
4386 busiest
= find_busiest_queue(&env
, group
);
4388 schedstat_inc(sd
, lb_nobusyq
[idle
]);
4392 BUG_ON(busiest
== env
.dst_rq
);
4394 schedstat_add(sd
, lb_imbalance
[idle
], env
.imbalance
);
4398 if (busiest
->nr_running
> 1) {
4400 * Attempt to move tasks. If find_busiest_group has found
4401 * an imbalance but busiest->nr_running <= 1, the group is
4402 * still unbalanced. ld_moved simply stays zero, so it is
4403 * correctly treated as an imbalance.
4405 env
.flags
|= LBF_ALL_PINNED
;
4406 env
.src_cpu
= busiest
->cpu
;
4407 env
.src_rq
= busiest
;
4408 env
.loop_max
= min(sysctl_sched_nr_migrate
, busiest
->nr_running
);
4410 update_h_load(env
.src_cpu
);
4412 local_irq_save(flags
);
4413 double_rq_lock(env
.dst_rq
, busiest
);
4416 * cur_ld_moved - load moved in current iteration
4417 * ld_moved - cumulative load moved across iterations
4419 cur_ld_moved
= move_tasks(&env
);
4420 ld_moved
+= cur_ld_moved
;
4421 double_rq_unlock(env
.dst_rq
, busiest
);
4422 local_irq_restore(flags
);
4424 if (env
.flags
& LBF_NEED_BREAK
) {
4425 env
.flags
&= ~LBF_NEED_BREAK
;
4430 * some other cpu did the load balance for us.
4432 if (cur_ld_moved
&& env
.dst_cpu
!= smp_processor_id())
4433 resched_cpu(env
.dst_cpu
);
4436 * Revisit (affine) tasks on src_cpu that couldn't be moved to
4437 * us and move them to an alternate dst_cpu in our sched_group
4438 * where they can run. The upper limit on how many times we
4439 * iterate on same src_cpu is dependent on number of cpus in our
4442 * This changes load balance semantics a bit on who can move
4443 * load to a given_cpu. In addition to the given_cpu itself
4444 * (or a ilb_cpu acting on its behalf where given_cpu is
4445 * nohz-idle), we now have balance_cpu in a position to move
4446 * load to given_cpu. In rare situations, this may cause
4447 * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
4448 * _independently_ and at _same_ time to move some load to
4449 * given_cpu) causing exceess load to be moved to given_cpu.
4450 * This however should not happen so much in practice and
4451 * moreover subsequent load balance cycles should correct the
4452 * excess load moved.
4454 if ((env
.flags
& LBF_SOME_PINNED
) && env
.imbalance
> 0 &&
4455 lb_iterations
++ < max_lb_iterations
) {
4457 env
.dst_rq
= cpu_rq(env
.new_dst_cpu
);
4458 env
.dst_cpu
= env
.new_dst_cpu
;
4459 env
.flags
&= ~LBF_SOME_PINNED
;
4461 env
.loop_break
= sched_nr_migrate_break
;
4463 * Go back to "more_balance" rather than "redo" since we
4464 * need to continue with same src_cpu.
4469 /* All tasks on this runqueue were pinned by CPU affinity */
4470 if (unlikely(env
.flags
& LBF_ALL_PINNED
)) {
4471 cpumask_clear_cpu(cpu_of(busiest
), cpus
);
4472 if (!cpumask_empty(cpus
)) {
4474 env
.loop_break
= sched_nr_migrate_break
;
4482 schedstat_inc(sd
, lb_failed
[idle
]);
4484 * Increment the failure counter only on periodic balance.
4485 * We do not want newidle balance, which can be very
4486 * frequent, pollute the failure counter causing
4487 * excessive cache_hot migrations and active balances.
4489 if (idle
!= CPU_NEWLY_IDLE
)
4490 sd
->nr_balance_failed
++;
4492 if (need_active_balance(&env
)) {
4493 raw_spin_lock_irqsave(&busiest
->lock
, flags
);
4495 /* don't kick the active_load_balance_cpu_stop,
4496 * if the curr task on busiest cpu can't be
4499 if (!cpumask_test_cpu(this_cpu
,
4500 tsk_cpus_allowed(busiest
->curr
))) {
4501 raw_spin_unlock_irqrestore(&busiest
->lock
,
4503 env
.flags
|= LBF_ALL_PINNED
;
4504 goto out_one_pinned
;
4508 * ->active_balance synchronizes accesses to
4509 * ->active_balance_work. Once set, it's cleared
4510 * only after active load balance is finished.
4512 if (!busiest
->active_balance
) {
4513 busiest
->active_balance
= 1;
4514 busiest
->push_cpu
= this_cpu
;
4517 raw_spin_unlock_irqrestore(&busiest
->lock
, flags
);
4519 if (active_balance
) {
4520 stop_one_cpu_nowait(cpu_of(busiest
),
4521 active_load_balance_cpu_stop
, busiest
,
4522 &busiest
->active_balance_work
);
4526 * We've kicked active balancing, reset the failure
4529 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
4532 sd
->nr_balance_failed
= 0;
4534 if (likely(!active_balance
)) {
4535 /* We were unbalanced, so reset the balancing interval */
4536 sd
->balance_interval
= sd
->min_interval
;
4539 * If we've begun active balancing, start to back off. This
4540 * case may not be covered by the all_pinned logic if there
4541 * is only 1 task on the busy runqueue (because we don't call
4544 if (sd
->balance_interval
< sd
->max_interval
)
4545 sd
->balance_interval
*= 2;
4551 schedstat_inc(sd
, lb_balanced
[idle
]);
4553 sd
->nr_balance_failed
= 0;
4556 /* tune up the balancing interval */
4557 if (((env
.flags
& LBF_ALL_PINNED
) &&
4558 sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
4559 (sd
->balance_interval
< sd
->max_interval
))
4560 sd
->balance_interval
*= 2;
4568 * idle_balance is called by schedule() if this_cpu is about to become
4569 * idle. Attempts to pull tasks from other CPUs.
4571 void idle_balance(int this_cpu
, struct rq
*this_rq
)
4573 struct sched_domain
*sd
;
4574 int pulled_task
= 0;
4575 unsigned long next_balance
= jiffies
+ HZ
;
4577 this_rq
->idle_stamp
= this_rq
->clock
;
4579 if (this_rq
->avg_idle
< sysctl_sched_migration_cost
)
4583 * Drop the rq->lock, but keep IRQ/preempt disabled.
4585 raw_spin_unlock(&this_rq
->lock
);
4587 update_shares(this_cpu
);
4589 for_each_domain(this_cpu
, sd
) {
4590 unsigned long interval
;
4593 if (!(sd
->flags
& SD_LOAD_BALANCE
))
4596 if (sd
->flags
& SD_BALANCE_NEWIDLE
) {
4597 /* If we've pulled tasks over stop searching: */
4598 pulled_task
= load_balance(this_cpu
, this_rq
,
4599 sd
, CPU_NEWLY_IDLE
, &balance
);
4602 interval
= msecs_to_jiffies(sd
->balance_interval
);
4603 if (time_after(next_balance
, sd
->last_balance
+ interval
))
4604 next_balance
= sd
->last_balance
+ interval
;
4606 this_rq
->idle_stamp
= 0;
4612 raw_spin_lock(&this_rq
->lock
);
4614 if (pulled_task
|| time_after(jiffies
, this_rq
->next_balance
)) {
4616 * We are going idle. next_balance may be set based on
4617 * a busy processor. So reset next_balance.
4619 this_rq
->next_balance
= next_balance
;
4624 * active_load_balance_cpu_stop is run by cpu stopper. It pushes
4625 * running tasks off the busiest CPU onto idle CPUs. It requires at
4626 * least 1 task to be running on each physical CPU where possible, and
4627 * avoids physical / logical imbalances.
4629 static int active_load_balance_cpu_stop(void *data
)
4631 struct rq
*busiest_rq
= data
;
4632 int busiest_cpu
= cpu_of(busiest_rq
);
4633 int target_cpu
= busiest_rq
->push_cpu
;
4634 struct rq
*target_rq
= cpu_rq(target_cpu
);
4635 struct sched_domain
*sd
;
4637 raw_spin_lock_irq(&busiest_rq
->lock
);
4639 /* make sure the requested cpu hasn't gone down in the meantime */
4640 if (unlikely(busiest_cpu
!= smp_processor_id() ||
4641 !busiest_rq
->active_balance
))
4644 /* Is there any task to move? */
4645 if (busiest_rq
->nr_running
<= 1)
4649 * This condition is "impossible", if it occurs
4650 * we need to fix it. Originally reported by
4651 * Bjorn Helgaas on a 128-cpu setup.
4653 BUG_ON(busiest_rq
== target_rq
);
4655 /* move a task from busiest_rq to target_rq */
4656 double_lock_balance(busiest_rq
, target_rq
);
4658 /* Search for an sd spanning us and the target CPU. */
4660 for_each_domain(target_cpu
, sd
) {
4661 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
4662 cpumask_test_cpu(busiest_cpu
, sched_domain_span(sd
)))
4667 struct lb_env env
= {
4669 .dst_cpu
= target_cpu
,
4670 .dst_rq
= target_rq
,
4671 .src_cpu
= busiest_rq
->cpu
,
4672 .src_rq
= busiest_rq
,
4676 schedstat_inc(sd
, alb_count
);
4678 if (move_one_task(&env
))
4679 schedstat_inc(sd
, alb_pushed
);
4681 schedstat_inc(sd
, alb_failed
);
4684 double_unlock_balance(busiest_rq
, target_rq
);
4686 busiest_rq
->active_balance
= 0;
4687 raw_spin_unlock_irq(&busiest_rq
->lock
);
4693 * idle load balancing details
4694 * - When one of the busy CPUs notice that there may be an idle rebalancing
4695 * needed, they will kick the idle load balancer, which then does idle
4696 * load balancing for all the idle CPUs.
4699 cpumask_var_t idle_cpus_mask
;
4701 unsigned long next_balance
; /* in jiffy units */
4702 } nohz ____cacheline_aligned
;
4704 static inline int find_new_ilb(int call_cpu
)
4706 int ilb
= cpumask_first(nohz
.idle_cpus_mask
);
4708 if (ilb
< nr_cpu_ids
&& idle_cpu(ilb
))
4715 * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
4716 * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
4717 * CPU (if there is one).
4719 static void nohz_balancer_kick(int cpu
)
4723 nohz
.next_balance
++;
4725 ilb_cpu
= find_new_ilb(cpu
);
4727 if (ilb_cpu
>= nr_cpu_ids
)
4730 if (test_and_set_bit(NOHZ_BALANCE_KICK
, nohz_flags(ilb_cpu
)))
4733 * Use smp_send_reschedule() instead of resched_cpu().
4734 * This way we generate a sched IPI on the target cpu which
4735 * is idle. And the softirq performing nohz idle load balance
4736 * will be run before returning from the IPI.
4738 smp_send_reschedule(ilb_cpu
);
4742 static inline void nohz_balance_exit_idle(int cpu
)
4744 if (unlikely(test_bit(NOHZ_TICK_STOPPED
, nohz_flags(cpu
)))) {
4745 cpumask_clear_cpu(cpu
, nohz
.idle_cpus_mask
);
4746 atomic_dec(&nohz
.nr_cpus
);
4747 clear_bit(NOHZ_TICK_STOPPED
, nohz_flags(cpu
));
4751 static inline void set_cpu_sd_state_busy(void)
4753 struct sched_domain
*sd
;
4754 int cpu
= smp_processor_id();
4756 if (!test_bit(NOHZ_IDLE
, nohz_flags(cpu
)))
4758 clear_bit(NOHZ_IDLE
, nohz_flags(cpu
));
4761 for_each_domain(cpu
, sd
)
4762 atomic_inc(&sd
->groups
->sgp
->nr_busy_cpus
);
4766 void set_cpu_sd_state_idle(void)
4768 struct sched_domain
*sd
;
4769 int cpu
= smp_processor_id();
4771 if (test_bit(NOHZ_IDLE
, nohz_flags(cpu
)))
4773 set_bit(NOHZ_IDLE
, nohz_flags(cpu
));
4776 for_each_domain(cpu
, sd
)
4777 atomic_dec(&sd
->groups
->sgp
->nr_busy_cpus
);
4782 * This routine will record that the cpu is going idle with tick stopped.
4783 * This info will be used in performing idle load balancing in the future.
4785 void nohz_balance_enter_idle(int cpu
)
4788 * If this cpu is going down, then nothing needs to be done.
4790 if (!cpu_active(cpu
))
4793 if (test_bit(NOHZ_TICK_STOPPED
, nohz_flags(cpu
)))
4796 cpumask_set_cpu(cpu
, nohz
.idle_cpus_mask
);
4797 atomic_inc(&nohz
.nr_cpus
);
4798 set_bit(NOHZ_TICK_STOPPED
, nohz_flags(cpu
));
4801 static int __cpuinit
sched_ilb_notifier(struct notifier_block
*nfb
,
4802 unsigned long action
, void *hcpu
)
4804 switch (action
& ~CPU_TASKS_FROZEN
) {
4806 nohz_balance_exit_idle(smp_processor_id());
4814 static DEFINE_SPINLOCK(balancing
);
4817 * Scale the max load_balance interval with the number of CPUs in the system.
4818 * This trades load-balance latency on larger machines for less cross talk.
4820 void update_max_interval(void)
4822 max_load_balance_interval
= HZ
*num_online_cpus()/10;
4826 * It checks each scheduling domain to see if it is due to be balanced,
4827 * and initiates a balancing operation if so.
4829 * Balancing parameters are set up in arch_init_sched_domains.
4831 static void rebalance_domains(int cpu
, enum cpu_idle_type idle
)
4834 struct rq
*rq
= cpu_rq(cpu
);
4835 unsigned long interval
;
4836 struct sched_domain
*sd
;
4837 /* Earliest time when we have to do rebalance again */
4838 unsigned long next_balance
= jiffies
+ 60*HZ
;
4839 int update_next_balance
= 0;
4845 for_each_domain(cpu
, sd
) {
4846 if (!(sd
->flags
& SD_LOAD_BALANCE
))
4849 interval
= sd
->balance_interval
;
4850 if (idle
!= CPU_IDLE
)
4851 interval
*= sd
->busy_factor
;
4853 /* scale ms to jiffies */
4854 interval
= msecs_to_jiffies(interval
);
4855 interval
= clamp(interval
, 1UL, max_load_balance_interval
);
4857 need_serialize
= sd
->flags
& SD_SERIALIZE
;
4859 if (need_serialize
) {
4860 if (!spin_trylock(&balancing
))
4864 if (time_after_eq(jiffies
, sd
->last_balance
+ interval
)) {
4865 if (load_balance(cpu
, rq
, sd
, idle
, &balance
)) {
4867 * We've pulled tasks over so either we're no
4870 idle
= CPU_NOT_IDLE
;
4872 sd
->last_balance
= jiffies
;
4875 spin_unlock(&balancing
);
4877 if (time_after(next_balance
, sd
->last_balance
+ interval
)) {
4878 next_balance
= sd
->last_balance
+ interval
;
4879 update_next_balance
= 1;
4883 * Stop the load balance at this level. There is another
4884 * CPU in our sched group which is doing load balancing more
4893 * next_balance will be updated only when there is a need.
4894 * When the cpu is attached to null domain for ex, it will not be
4897 if (likely(update_next_balance
))
4898 rq
->next_balance
= next_balance
;
4903 * In CONFIG_NO_HZ case, the idle balance kickee will do the
4904 * rebalancing for all the cpus for whom scheduler ticks are stopped.
4906 static void nohz_idle_balance(int this_cpu
, enum cpu_idle_type idle
)
4908 struct rq
*this_rq
= cpu_rq(this_cpu
);
4912 if (idle
!= CPU_IDLE
||
4913 !test_bit(NOHZ_BALANCE_KICK
, nohz_flags(this_cpu
)))
4916 for_each_cpu(balance_cpu
, nohz
.idle_cpus_mask
) {
4917 if (balance_cpu
== this_cpu
|| !idle_cpu(balance_cpu
))
4921 * If this cpu gets work to do, stop the load balancing
4922 * work being done for other cpus. Next load
4923 * balancing owner will pick it up.
4928 rq
= cpu_rq(balance_cpu
);
4930 raw_spin_lock_irq(&rq
->lock
);
4931 update_rq_clock(rq
);
4932 update_idle_cpu_load(rq
);
4933 raw_spin_unlock_irq(&rq
->lock
);
4935 rebalance_domains(balance_cpu
, CPU_IDLE
);
4937 if (time_after(this_rq
->next_balance
, rq
->next_balance
))
4938 this_rq
->next_balance
= rq
->next_balance
;
4940 nohz
.next_balance
= this_rq
->next_balance
;
4942 clear_bit(NOHZ_BALANCE_KICK
, nohz_flags(this_cpu
));
4946 * Current heuristic for kicking the idle load balancer in the presence
4947 * of an idle cpu is the system.
4948 * - This rq has more than one task.
4949 * - At any scheduler domain level, this cpu's scheduler group has multiple
4950 * busy cpu's exceeding the group's power.
4951 * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
4952 * domain span are idle.
4954 static inline int nohz_kick_needed(struct rq
*rq
, int cpu
)
4956 unsigned long now
= jiffies
;
4957 struct sched_domain
*sd
;
4959 if (unlikely(idle_cpu(cpu
)))
4963 * We may be recently in ticked or tickless idle mode. At the first
4964 * busy tick after returning from idle, we will update the busy stats.
4966 set_cpu_sd_state_busy();
4967 nohz_balance_exit_idle(cpu
);
4970 * None are in tickless mode and hence no need for NOHZ idle load
4973 if (likely(!atomic_read(&nohz
.nr_cpus
)))
4976 if (time_before(now
, nohz
.next_balance
))
4979 if (rq
->nr_running
>= 2)
4983 for_each_domain(cpu
, sd
) {
4984 struct sched_group
*sg
= sd
->groups
;
4985 struct sched_group_power
*sgp
= sg
->sgp
;
4986 int nr_busy
= atomic_read(&sgp
->nr_busy_cpus
);
4988 if (sd
->flags
& SD_SHARE_PKG_RESOURCES
&& nr_busy
> 1)
4989 goto need_kick_unlock
;
4991 if (sd
->flags
& SD_ASYM_PACKING
&& nr_busy
!= sg
->group_weight
4992 && (cpumask_first_and(nohz
.idle_cpus_mask
,
4993 sched_domain_span(sd
)) < cpu
))
4994 goto need_kick_unlock
;
4996 if (!(sd
->flags
& (SD_SHARE_PKG_RESOURCES
| SD_ASYM_PACKING
)))
5008 static void nohz_idle_balance(int this_cpu
, enum cpu_idle_type idle
) { }
5012 * run_rebalance_domains is triggered when needed from the scheduler tick.
5013 * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
5015 static void run_rebalance_domains(struct softirq_action
*h
)
5017 int this_cpu
= smp_processor_id();
5018 struct rq
*this_rq
= cpu_rq(this_cpu
);
5019 enum cpu_idle_type idle
= this_rq
->idle_balance
?
5020 CPU_IDLE
: CPU_NOT_IDLE
;
5022 rebalance_domains(this_cpu
, idle
);
5025 * If this cpu has a pending nohz_balance_kick, then do the
5026 * balancing on behalf of the other idle cpus whose ticks are
5029 nohz_idle_balance(this_cpu
, idle
);
5032 static inline int on_null_domain(int cpu
)
5034 return !rcu_dereference_sched(cpu_rq(cpu
)->sd
);
5038 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
5040 void trigger_load_balance(struct rq
*rq
, int cpu
)
5042 /* Don't need to rebalance while attached to NULL domain */
5043 if (time_after_eq(jiffies
, rq
->next_balance
) &&
5044 likely(!on_null_domain(cpu
)))
5045 raise_softirq(SCHED_SOFTIRQ
);
5047 if (nohz_kick_needed(rq
, cpu
) && likely(!on_null_domain(cpu
)))
5048 nohz_balancer_kick(cpu
);
5052 static void rq_online_fair(struct rq
*rq
)
5057 static void rq_offline_fair(struct rq
*rq
)
5061 /* Ensure any throttled groups are reachable by pick_next_task */
5062 unthrottle_offline_cfs_rqs(rq
);
5065 #endif /* CONFIG_SMP */
5068 * scheduler tick hitting a task of our scheduling class:
5070 static void task_tick_fair(struct rq
*rq
, struct task_struct
*curr
, int queued
)
5072 struct cfs_rq
*cfs_rq
;
5073 struct sched_entity
*se
= &curr
->se
;
5075 for_each_sched_entity(se
) {
5076 cfs_rq
= cfs_rq_of(se
);
5077 entity_tick(cfs_rq
, se
, queued
);
5080 if (sched_feat_numa(NUMA
))
5081 task_tick_numa(rq
, curr
);
5085 * called on fork with the child task as argument from the parent's context
5086 * - child not yet on the tasklist
5087 * - preemption disabled
5089 static void task_fork_fair(struct task_struct
*p
)
5091 struct cfs_rq
*cfs_rq
;
5092 struct sched_entity
*se
= &p
->se
, *curr
;
5093 int this_cpu
= smp_processor_id();
5094 struct rq
*rq
= this_rq();
5095 unsigned long flags
;
5097 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5099 update_rq_clock(rq
);
5101 cfs_rq
= task_cfs_rq(current
);
5102 curr
= cfs_rq
->curr
;
5104 if (unlikely(task_cpu(p
) != this_cpu
)) {
5106 __set_task_cpu(p
, this_cpu
);
5110 update_curr(cfs_rq
);
5113 se
->vruntime
= curr
->vruntime
;
5114 place_entity(cfs_rq
, se
, 1);
5116 if (sysctl_sched_child_runs_first
&& curr
&& entity_before(curr
, se
)) {
5118 * Upon rescheduling, sched_class::put_prev_task() will place
5119 * 'current' within the tree based on its new key value.
5121 swap(curr
->vruntime
, se
->vruntime
);
5122 resched_task(rq
->curr
);
5125 se
->vruntime
-= cfs_rq
->min_vruntime
;
5127 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5131 * Priority of the task has changed. Check to see if we preempt
5135 prio_changed_fair(struct rq
*rq
, struct task_struct
*p
, int oldprio
)
5141 * Reschedule if we are currently running on this runqueue and
5142 * our priority decreased, or if we are not currently running on
5143 * this runqueue and our priority is higher than the current's
5145 if (rq
->curr
== p
) {
5146 if (p
->prio
> oldprio
)
5147 resched_task(rq
->curr
);
5149 check_preempt_curr(rq
, p
, 0);
5152 static void switched_from_fair(struct rq
*rq
, struct task_struct
*p
)
5154 struct sched_entity
*se
= &p
->se
;
5155 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
5158 * Ensure the task's vruntime is normalized, so that when its
5159 * switched back to the fair class the enqueue_entity(.flags=0) will
5160 * do the right thing.
5162 * If it was on_rq, then the dequeue_entity(.flags=0) will already
5163 * have normalized the vruntime, if it was !on_rq, then only when
5164 * the task is sleeping will it still have non-normalized vruntime.
5166 if (!se
->on_rq
&& p
->state
!= TASK_RUNNING
) {
5168 * Fix up our vruntime so that the current sleep doesn't
5169 * cause 'unlimited' sleep bonus.
5171 place_entity(cfs_rq
, se
, 0);
5172 se
->vruntime
-= cfs_rq
->min_vruntime
;
5177 * We switched to the sched_fair class.
5179 static void switched_to_fair(struct rq
*rq
, struct task_struct
*p
)
5185 * We were most likely switched from sched_rt, so
5186 * kick off the schedule if running, otherwise just see
5187 * if we can still preempt the current task.
5190 resched_task(rq
->curr
);
5192 check_preempt_curr(rq
, p
, 0);
5195 /* Account for a task changing its policy or group.
5197 * This routine is mostly called to set cfs_rq->curr field when a task
5198 * migrates between groups/classes.
5200 static void set_curr_task_fair(struct rq
*rq
)
5202 struct sched_entity
*se
= &rq
->curr
->se
;
5204 for_each_sched_entity(se
) {
5205 struct cfs_rq
*cfs_rq
= cfs_rq_of(se
);
5207 set_next_entity(cfs_rq
, se
);
5208 /* ensure bandwidth has been allocated on our new cfs_rq */
5209 account_cfs_rq_runtime(cfs_rq
, 0);
5213 void init_cfs_rq(struct cfs_rq
*cfs_rq
)
5215 cfs_rq
->tasks_timeline
= RB_ROOT
;
5216 cfs_rq
->min_vruntime
= (u64
)(-(1LL << 20));
5217 #ifndef CONFIG_64BIT
5218 cfs_rq
->min_vruntime_copy
= cfs_rq
->min_vruntime
;
5222 #ifdef CONFIG_FAIR_GROUP_SCHED
5223 static void task_move_group_fair(struct task_struct
*p
, int on_rq
)
5226 * If the task was not on the rq at the time of this cgroup movement
5227 * it must have been asleep, sleeping tasks keep their ->vruntime
5228 * absolute on their old rq until wakeup (needed for the fair sleeper
5229 * bonus in place_entity()).
5231 * If it was on the rq, we've just 'preempted' it, which does convert
5232 * ->vruntime to a relative base.
5234 * Make sure both cases convert their relative position when migrating
5235 * to another cgroup's rq. This does somewhat interfere with the
5236 * fair sleeper stuff for the first placement, but who cares.
5239 * When !on_rq, vruntime of the task has usually NOT been normalized.
5240 * But there are some cases where it has already been normalized:
5242 * - Moving a forked child which is waiting for being woken up by
5243 * wake_up_new_task().
5244 * - Moving a task which has been woken up by try_to_wake_up() and
5245 * waiting for actually being woken up by sched_ttwu_pending().
5247 * To prevent boost or penalty in the new cfs_rq caused by delta
5248 * min_vruntime between the two cfs_rqs, we skip vruntime adjustment.
5250 if (!on_rq
&& (!p
->se
.sum_exec_runtime
|| p
->state
== TASK_WAKING
))
5254 p
->se
.vruntime
-= cfs_rq_of(&p
->se
)->min_vruntime
;
5255 set_task_rq(p
, task_cpu(p
));
5257 p
->se
.vruntime
+= cfs_rq_of(&p
->se
)->min_vruntime
;
5260 void free_fair_sched_group(struct task_group
*tg
)
5264 destroy_cfs_bandwidth(tg_cfs_bandwidth(tg
));
5266 for_each_possible_cpu(i
) {
5268 kfree(tg
->cfs_rq
[i
]);
5277 int alloc_fair_sched_group(struct task_group
*tg
, struct task_group
*parent
)
5279 struct cfs_rq
*cfs_rq
;
5280 struct sched_entity
*se
;
5283 tg
->cfs_rq
= kzalloc(sizeof(cfs_rq
) * nr_cpu_ids
, GFP_KERNEL
);
5286 tg
->se
= kzalloc(sizeof(se
) * nr_cpu_ids
, GFP_KERNEL
);
5290 tg
->shares
= NICE_0_LOAD
;
5292 init_cfs_bandwidth(tg_cfs_bandwidth(tg
));
5294 for_each_possible_cpu(i
) {
5295 cfs_rq
= kzalloc_node(sizeof(struct cfs_rq
),
5296 GFP_KERNEL
, cpu_to_node(i
));
5300 se
= kzalloc_node(sizeof(struct sched_entity
),
5301 GFP_KERNEL
, cpu_to_node(i
));
5305 init_cfs_rq(cfs_rq
);
5306 init_tg_cfs_entry(tg
, cfs_rq
, se
, i
, parent
->se
[i
]);
5317 void unregister_fair_sched_group(struct task_group
*tg
, int cpu
)
5319 struct rq
*rq
= cpu_rq(cpu
);
5320 unsigned long flags
;
5323 * Only empty task groups can be destroyed; so we can speculatively
5324 * check on_list without danger of it being re-added.
5326 if (!tg
->cfs_rq
[cpu
]->on_list
)
5329 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5330 list_del_leaf_cfs_rq(tg
->cfs_rq
[cpu
]);
5331 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5334 void init_tg_cfs_entry(struct task_group
*tg
, struct cfs_rq
*cfs_rq
,
5335 struct sched_entity
*se
, int cpu
,
5336 struct sched_entity
*parent
)
5338 struct rq
*rq
= cpu_rq(cpu
);
5343 /* allow initial update_cfs_load() to truncate */
5344 cfs_rq
->load_stamp
= 1;
5346 init_cfs_rq_runtime(cfs_rq
);
5348 tg
->cfs_rq
[cpu
] = cfs_rq
;
5351 /* se could be NULL for root_task_group */
5356 se
->cfs_rq
= &rq
->cfs
;
5358 se
->cfs_rq
= parent
->my_q
;
5361 update_load_set(&se
->load
, 0);
5362 se
->parent
= parent
;
5365 static DEFINE_MUTEX(shares_mutex
);
5367 int sched_group_set_shares(struct task_group
*tg
, unsigned long shares
)
5370 unsigned long flags
;
5373 * We can't change the weight of the root cgroup.
5378 shares
= clamp(shares
, scale_load(MIN_SHARES
), scale_load(MAX_SHARES
));
5380 mutex_lock(&shares_mutex
);
5381 if (tg
->shares
== shares
)
5384 tg
->shares
= shares
;
5385 for_each_possible_cpu(i
) {
5386 struct rq
*rq
= cpu_rq(i
);
5387 struct sched_entity
*se
;
5390 /* Propagate contribution to hierarchy */
5391 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5392 for_each_sched_entity(se
)
5393 update_cfs_shares(group_cfs_rq(se
));
5394 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5398 mutex_unlock(&shares_mutex
);
5401 #else /* CONFIG_FAIR_GROUP_SCHED */
5403 void free_fair_sched_group(struct task_group
*tg
) { }
5405 int alloc_fair_sched_group(struct task_group
*tg
, struct task_group
*parent
)
5410 void unregister_fair_sched_group(struct task_group
*tg
, int cpu
) { }
5412 #endif /* CONFIG_FAIR_GROUP_SCHED */
5415 static unsigned int get_rr_interval_fair(struct rq
*rq
, struct task_struct
*task
)
5417 struct sched_entity
*se
= &task
->se
;
5418 unsigned int rr_interval
= 0;
5421 * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
5424 if (rq
->cfs
.load
.weight
)
5425 rr_interval
= NS_TO_JIFFIES(sched_slice(&rq
->cfs
, se
));
5431 * All the scheduling class methods:
5433 const struct sched_class fair_sched_class
= {
5434 .next
= &idle_sched_class
,
5435 .enqueue_task
= enqueue_task_fair
,
5436 .dequeue_task
= dequeue_task_fair
,
5437 .yield_task
= yield_task_fair
,
5438 .yield_to_task
= yield_to_task_fair
,
5440 .check_preempt_curr
= check_preempt_wakeup
,
5442 .pick_next_task
= pick_next_task_fair
,
5443 .put_prev_task
= put_prev_task_fair
,
5446 .select_task_rq
= select_task_rq_fair
,
5448 .rq_online
= rq_online_fair
,
5449 .rq_offline
= rq_offline_fair
,
5451 .task_waking
= task_waking_fair
,
5454 .set_curr_task
= set_curr_task_fair
,
5455 .task_tick
= task_tick_fair
,
5456 .task_fork
= task_fork_fair
,
5458 .prio_changed
= prio_changed_fair
,
5459 .switched_from
= switched_from_fair
,
5460 .switched_to
= switched_to_fair
,
5462 .get_rr_interval
= get_rr_interval_fair
,
5464 #ifdef CONFIG_FAIR_GROUP_SCHED
5465 .task_move_group
= task_move_group_fair
,
5469 #ifdef CONFIG_SCHED_DEBUG
5470 void print_cfs_stats(struct seq_file
*m
, int cpu
)
5472 struct cfs_rq
*cfs_rq
;
5475 for_each_leaf_cfs_rq(cpu_rq(cpu
), cfs_rq
)
5476 print_cfs_rq(m
, cpu
, cfs_rq
);
5481 __init
void init_sched_fair_class(void)
5484 open_softirq(SCHED_SOFTIRQ
, run_rebalance_domains
);
5487 nohz
.next_balance
= jiffies
;
5488 zalloc_cpumask_var(&nohz
.idle_cpus_mask
, GFP_NOWAIT
);
5489 cpu_notifier(sched_ilb_notifier
, 0);