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
785 unsigned int sysctl_numa_balancing_scan_period_min = 100;
786 unsigned int sysctl_numa_balancing_scan_period_max = 100*16;
788 /* Portion of address space to scan in MB */
789 unsigned int sysctl_numa_balancing_scan_size = 256;
791 static void task_numa_placement(struct task_struct *p)
793 int seq = ACCESS_ONCE(p->mm->numa_scan_seq);
795 if (p->numa_scan_seq == seq)
797 p->numa_scan_seq = seq;
799 /* FIXME: Scheduling placement policy hints go here */
803 * Got a PROT_NONE fault for a page on @node.
805 void task_numa_fault(int node, int pages)
807 struct task_struct *p = current;
809 /* FIXME: Allocate task-specific structure for placement policy here */
811 task_numa_placement(p);
814 static void reset_ptenuma_scan(struct task_struct *p)
816 ACCESS_ONCE(p->mm->numa_scan_seq)++;
817 p->mm->numa_scan_offset = 0;
821 * The expensive part of numa migration is done from task_work context.
822 * Triggered from task_tick_numa().
824 void task_numa_work(struct callback_head *work)
826 unsigned long migrate, next_scan, now = jiffies;
827 struct task_struct *p = current;
828 struct mm_struct *mm = p->mm;
829 struct vm_area_struct *vma;
830 unsigned long offset, end;
833 WARN_ON_ONCE(p != container_of(work, struct task_struct, numa_work));
835 work->next = work; /* protect against double add */
837 * Who cares about NUMA placement when they're dying.
839 * NOTE: make sure not to dereference p->mm before this check,
840 * exit_task_work() happens _after_ exit_mm() so we could be called
841 * without p->mm even though we still had it when we enqueued this
844 if (p->flags & PF_EXITING)
848 * Enforce maximal scan/migration frequency..
850 migrate = mm->numa_next_scan;
851 if (time_before(now, migrate))
854 if (p->numa_scan_period == 0)
855 p->numa_scan_period = sysctl_numa_balancing_scan_period_min;
857 next_scan = now + 2*msecs_to_jiffies(p->numa_scan_period);
858 if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate)
861 offset = mm->numa_scan_offset;
862 length = sysctl_numa_balancing_scan_size;
865 down_read(&mm->mmap_sem);
866 vma = find_vma(mm, offset);
868 reset_ptenuma_scan(p);
872 for (; vma && length > 0; vma = vma->vm_next) {
873 if (!vma_migratable(vma))
876 /* Skip small VMAs. They are not likely to be of relevance */
877 if (((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < HPAGE_PMD_NR)
880 offset = max(offset, vma->vm_start);
881 end = min(ALIGN(offset + length, HPAGE_SIZE), vma->vm_end);
882 length -= end - offset;
884 change_prot_numa(vma, offset, end);
890 * It is possible to reach the end of the VMA list but the last few VMAs are
891 * not guaranteed to the vma_migratable. If they are not, we would find the
892 * !migratable VMA on the next scan but not reset the scanner to the start
896 mm->numa_scan_offset = offset;
898 reset_ptenuma_scan(p);
899 up_read(&mm->mmap_sem);
903 * Drive the periodic memory faults..
905 void task_tick_numa(struct rq *rq, struct task_struct *curr)
907 struct callback_head *work = &curr->numa_work;
911 * We don't care about NUMA placement if we don't have memory.
913 if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work)
917 * Using runtime rather than walltime has the dual advantage that
918 * we (mostly) drive the selection from busy threads and that the
919 * task needs to have done some actual work before we bother with
922 now = curr->se.sum_exec_runtime;
923 period = (u64)curr->numa_scan_period * NSEC_PER_MSEC;
925 if (now - curr->node_stamp > period) {
926 curr->node_stamp = now;
928 if (!time_before(jiffies, curr->mm->numa_next_scan)) {
929 init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */
930 task_work_add(curr, work, true);
935 static void task_tick_numa(struct rq *rq, struct task_struct *curr)
938 #endif /* CONFIG_NUMA_BALANCING */
941 account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
943 update_load_add(&cfs_rq->load, se->load.weight);
944 if (!parent_entity(se))
945 update_load_add(&rq_of(cfs_rq)->load, se->load.weight);
947 if (entity_is_task(se))
948 list_add(&se->group_node, &rq_of(cfs_rq)->cfs_tasks);
950 cfs_rq->nr_running++;
954 account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
956 update_load_sub(&cfs_rq->load, se->load.weight);
957 if (!parent_entity(se))
958 update_load_sub(&rq_of(cfs_rq)->load, se->load.weight);
959 if (entity_is_task(se))
960 list_del_init(&se->group_node);
961 cfs_rq->nr_running--;
964 #ifdef CONFIG_FAIR_GROUP_SCHED
965 /* we need this in update_cfs_load and load-balance functions below */
966 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
968 static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq,
971 struct task_group *tg = cfs_rq->tg;
974 load_avg = div64_u64(cfs_rq->load_avg, cfs_rq->load_period+1);
975 load_avg -= cfs_rq->load_contribution;
977 if (global_update || abs(load_avg) > cfs_rq->load_contribution / 8) {
978 atomic_add(load_avg, &tg->load_weight);
979 cfs_rq->load_contribution += load_avg;
983 static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
985 u64 period = sysctl_sched_shares_window;
987 unsigned long load = cfs_rq->load.weight;
989 if (cfs_rq->tg == &root_task_group || throttled_hierarchy(cfs_rq))
992 now = rq_of(cfs_rq)->clock_task;
993 delta = now - cfs_rq->load_stamp;
995 /* truncate load history at 4 idle periods */
996 if (cfs_rq->load_stamp > cfs_rq->load_last &&
997 now - cfs_rq->load_last > 4 * period) {
998 cfs_rq->load_period = 0;
999 cfs_rq->load_avg = 0;
1003 cfs_rq->load_stamp = now;
1004 cfs_rq->load_unacc_exec_time = 0;
1005 cfs_rq->load_period += delta;
1007 cfs_rq->load_last = now;
1008 cfs_rq->load_avg += delta * load;
1011 /* consider updating load contribution on each fold or truncate */
1012 if (global_update || cfs_rq->load_period > period
1013 || !cfs_rq->load_period)
1014 update_cfs_rq_load_contribution(cfs_rq, global_update);
1016 while (cfs_rq->load_period > period) {
1018 * Inline assembly required to prevent the compiler
1019 * optimising this loop into a divmod call.
1020 * See __iter_div_u64_rem() for another example of this.
1022 asm("" : "+rm" (cfs_rq->load_period));
1023 cfs_rq->load_period /= 2;
1024 cfs_rq->load_avg /= 2;
1027 if (!cfs_rq->curr && !cfs_rq->nr_running && !cfs_rq->load_avg)
1028 list_del_leaf_cfs_rq(cfs_rq);
1031 static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq)
1036 * Use this CPU's actual weight instead of the last load_contribution
1037 * to gain a more accurate current total weight. See
1038 * update_cfs_rq_load_contribution().
1040 tg_weight = atomic_read(&tg->load_weight);
1041 tg_weight -= cfs_rq->load_contribution;
1042 tg_weight += cfs_rq->load.weight;
1047 static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
1049 long tg_weight, load, shares;
1051 tg_weight = calc_tg_weight(tg, cfs_rq);
1052 load = cfs_rq->load.weight;
1054 shares = (tg->shares * load);
1056 shares /= tg_weight;
1058 if (shares < MIN_SHARES)
1059 shares = MIN_SHARES;
1060 if (shares > tg->shares)
1061 shares = tg->shares;
1066 static void update_entity_shares_tick(struct cfs_rq *cfs_rq)
1068 if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
1069 update_cfs_load(cfs_rq, 0);
1070 update_cfs_shares(cfs_rq);
1073 # else /* CONFIG_SMP */
1074 static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
1078 static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
1083 static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
1086 # endif /* CONFIG_SMP */
1087 static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
1088 unsigned long weight)
1091 /* commit outstanding execution time */
1092 if (cfs_rq->curr == se)
1093 update_curr(cfs_rq);
1094 account_entity_dequeue(cfs_rq, se);
1097 update_load_set(&se->load, weight);
1100 account_entity_enqueue(cfs_rq, se);
1103 static void update_cfs_shares(struct cfs_rq *cfs_rq)
1105 struct task_group *tg;
1106 struct sched_entity *se;
1110 se = tg->se[cpu_of(rq_of(cfs_rq))];
1111 if (!se || throttled_hierarchy(cfs_rq))
1114 if (likely(se->load.weight == tg->shares))
1117 shares = calc_cfs_shares(cfs_rq, tg);
1119 reweight_entity(cfs_rq_of(se), se, shares);
1121 #else /* CONFIG_FAIR_GROUP_SCHED */
1122 static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
1126 static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
1130 static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
1133 #endif /* CONFIG_FAIR_GROUP_SCHED */
1135 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
1137 #ifdef CONFIG_SCHEDSTATS
1138 struct task_struct *tsk = NULL;
1140 if (entity_is_task(se))
1143 if (se->statistics.sleep_start) {
1144 u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start;
1149 if (unlikely(delta > se->statistics.sleep_max))
1150 se->statistics.sleep_max = delta;
1152 se->statistics.sleep_start = 0;
1153 se->statistics.sum_sleep_runtime += delta;
1156 account_scheduler_latency(tsk, delta >> 10, 1);
1157 trace_sched_stat_sleep(tsk, delta);
1160 if (se->statistics.block_start) {
1161 u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start;
1166 if (unlikely(delta > se->statistics.block_max))
1167 se->statistics.block_max = delta;
1169 se->statistics.block_start = 0;
1170 se->statistics.sum_sleep_runtime += delta;
1173 if (tsk->in_iowait) {
1174 se->statistics.iowait_sum += delta;
1175 se->statistics.iowait_count++;
1176 trace_sched_stat_iowait(tsk, delta);
1179 trace_sched_stat_blocked(tsk, delta);
1182 * Blocking time is in units of nanosecs, so shift by
1183 * 20 to get a milliseconds-range estimation of the
1184 * amount of time that the task spent sleeping:
1186 if (unlikely(prof_on == SLEEP_PROFILING)) {
1187 profile_hits(SLEEP_PROFILING,
1188 (void *)get_wchan(tsk),
1191 account_scheduler_latency(tsk, delta >> 10, 0);
1197 static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
1199 #ifdef CONFIG_SCHED_DEBUG
1200 s64 d = se->vruntime - cfs_rq->min_vruntime;
1205 if (d > 3*sysctl_sched_latency)
1206 schedstat_inc(cfs_rq, nr_spread_over);
1211 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
1213 u64 vruntime = cfs_rq->min_vruntime;
1216 * The 'current' period is already promised to the current tasks,
1217 * however the extra weight of the new task will slow them down a
1218 * little, place the new task so that it fits in the slot that
1219 * stays open at the end.
1221 if (initial && sched_feat(START_DEBIT))
1222 vruntime += sched_vslice(cfs_rq, se);
1224 /* sleeps up to a single latency don't count. */
1226 unsigned long thresh = sysctl_sched_latency;
1229 * Halve their sleep time's effect, to allow
1230 * for a gentler effect of sleepers:
1232 if (sched_feat(GENTLE_FAIR_SLEEPERS))
1238 /* ensure we never gain time by being placed backwards. */
1239 vruntime = max_vruntime(se->vruntime, vruntime);
1241 se->vruntime = vruntime;
1244 static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
1247 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1250 * Update the normalized vruntime before updating min_vruntime
1251 * through callig update_curr().
1253 if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING))
1254 se->vruntime += cfs_rq->min_vruntime;
1257 * Update run-time statistics of the 'current'.
1259 update_curr(cfs_rq);
1260 update_cfs_load(cfs_rq, 0);
1261 account_entity_enqueue(cfs_rq, se);
1262 update_cfs_shares(cfs_rq);
1264 if (flags & ENQUEUE_WAKEUP) {
1265 place_entity(cfs_rq, se, 0);
1266 enqueue_sleeper(cfs_rq, se);
1269 update_stats_enqueue(cfs_rq, se);
1270 check_spread(cfs_rq, se);
1271 if (se != cfs_rq->curr)
1272 __enqueue_entity(cfs_rq, se);
1275 if (cfs_rq->nr_running == 1) {
1276 list_add_leaf_cfs_rq(cfs_rq);
1277 check_enqueue_throttle(cfs_rq);
1281 static void __clear_buddies_last(struct sched_entity *se)
1283 for_each_sched_entity(se) {
1284 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1285 if (cfs_rq->last == se)
1286 cfs_rq->last = NULL;
1292 static void __clear_buddies_next(struct sched_entity *se)
1294 for_each_sched_entity(se) {
1295 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1296 if (cfs_rq->next == se)
1297 cfs_rq->next = NULL;
1303 static void __clear_buddies_skip(struct sched_entity *se)
1305 for_each_sched_entity(se) {
1306 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1307 if (cfs_rq->skip == se)
1308 cfs_rq->skip = NULL;
1314 static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
1316 if (cfs_rq->last == se)
1317 __clear_buddies_last(se);
1319 if (cfs_rq->next == se)
1320 __clear_buddies_next(se);
1322 if (cfs_rq->skip == se)
1323 __clear_buddies_skip(se);
1326 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
1329 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1332 * Update run-time statistics of the 'current'.
1334 update_curr(cfs_rq);
1336 update_stats_dequeue(cfs_rq, se);
1337 if (flags & DEQUEUE_SLEEP) {
1338 #ifdef CONFIG_SCHEDSTATS
1339 if (entity_is_task(se)) {
1340 struct task_struct *tsk = task_of(se);
1342 if (tsk->state & TASK_INTERRUPTIBLE)
1343 se->statistics.sleep_start = rq_of(cfs_rq)->clock;
1344 if (tsk->state & TASK_UNINTERRUPTIBLE)
1345 se->statistics.block_start = rq_of(cfs_rq)->clock;
1350 clear_buddies(cfs_rq, se);
1352 if (se != cfs_rq->curr)
1353 __dequeue_entity(cfs_rq, se);
1355 update_cfs_load(cfs_rq, 0);
1356 account_entity_dequeue(cfs_rq, se);
1359 * Normalize the entity after updating the min_vruntime because the
1360 * update can refer to the ->curr item and we need to reflect this
1361 * movement in our normalized position.
1363 if (!(flags & DEQUEUE_SLEEP))
1364 se->vruntime -= cfs_rq->min_vruntime;
1366 /* return excess runtime on last dequeue */
1367 return_cfs_rq_runtime(cfs_rq);
1369 update_min_vruntime(cfs_rq);
1370 update_cfs_shares(cfs_rq);
1374 * Preempt the current task with a newly woken task if needed:
1377 check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
1379 unsigned long ideal_runtime, delta_exec;
1380 struct sched_entity *se;
1383 ideal_runtime = sched_slice(cfs_rq, curr);
1384 delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
1385 if (delta_exec > ideal_runtime) {
1386 resched_task(rq_of(cfs_rq)->curr);
1388 * The current task ran long enough, ensure it doesn't get
1389 * re-elected due to buddy favours.
1391 clear_buddies(cfs_rq, curr);
1396 * Ensure that a task that missed wakeup preemption by a
1397 * narrow margin doesn't have to wait for a full slice.
1398 * This also mitigates buddy induced latencies under load.
1400 if (delta_exec < sysctl_sched_min_granularity)
1403 se = __pick_first_entity(cfs_rq);
1404 delta = curr->vruntime - se->vruntime;
1409 if (delta > ideal_runtime)
1410 resched_task(rq_of(cfs_rq)->curr);
1414 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
1416 /* 'current' is not kept within the tree. */
1419 * Any task has to be enqueued before it get to execute on
1420 * a CPU. So account for the time it spent waiting on the
1423 update_stats_wait_end(cfs_rq, se);
1424 __dequeue_entity(cfs_rq, se);
1427 update_stats_curr_start(cfs_rq, se);
1429 #ifdef CONFIG_SCHEDSTATS
1431 * Track our maximum slice length, if the CPU's load is at
1432 * least twice that of our own weight (i.e. dont track it
1433 * when there are only lesser-weight tasks around):
1435 if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
1436 se->statistics.slice_max = max(se->statistics.slice_max,
1437 se->sum_exec_runtime - se->prev_sum_exec_runtime);
1440 se->prev_sum_exec_runtime = se->sum_exec_runtime;
1444 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
1447 * Pick the next process, keeping these things in mind, in this order:
1448 * 1) keep things fair between processes/task groups
1449 * 2) pick the "next" process, since someone really wants that to run
1450 * 3) pick the "last" process, for cache locality
1451 * 4) do not run the "skip" process, if something else is available
1453 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
1455 struct sched_entity *se = __pick_first_entity(cfs_rq);
1456 struct sched_entity *left = se;
1459 * Avoid running the skip buddy, if running something else can
1460 * be done without getting too unfair.
1462 if (cfs_rq->skip == se) {
1463 struct sched_entity *second = __pick_next_entity(se);
1464 if (second && wakeup_preempt_entity(second, left) < 1)
1469 * Prefer last buddy, try to return the CPU to a preempted task.
1471 if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
1475 * Someone really wants this to run. If it's not unfair, run it.
1477 if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
1480 clear_buddies(cfs_rq, se);
1485 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
1487 static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
1490 * If still on the runqueue then deactivate_task()
1491 * was not called and update_curr() has to be done:
1494 update_curr(cfs_rq);
1496 /* throttle cfs_rqs exceeding runtime */
1497 check_cfs_rq_runtime(cfs_rq);
1499 check_spread(cfs_rq, prev);
1501 update_stats_wait_start(cfs_rq, prev);
1502 /* Put 'current' back into the tree. */
1503 __enqueue_entity(cfs_rq, prev);
1505 cfs_rq->curr = NULL;
1509 entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
1512 * Update run-time statistics of the 'current'.
1514 update_curr(cfs_rq);
1517 * Update share accounting for long-running entities.
1519 update_entity_shares_tick(cfs_rq);
1521 #ifdef CONFIG_SCHED_HRTICK
1523 * queued ticks are scheduled to match the slice, so don't bother
1524 * validating it and just reschedule.
1527 resched_task(rq_of(cfs_rq)->curr);
1531 * don't let the period tick interfere with the hrtick preemption
1533 if (!sched_feat(DOUBLE_TICK) &&
1534 hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
1538 if (cfs_rq->nr_running > 1)
1539 check_preempt_tick(cfs_rq, curr);
1543 /**************************************************
1544 * CFS bandwidth control machinery
1547 #ifdef CONFIG_CFS_BANDWIDTH
1549 #ifdef HAVE_JUMP_LABEL
1550 static struct static_key __cfs_bandwidth_used;
1552 static inline bool cfs_bandwidth_used(void)
1554 return static_key_false(&__cfs_bandwidth_used);
1557 void account_cfs_bandwidth_used(int enabled, int was_enabled)
1559 /* only need to count groups transitioning between enabled/!enabled */
1560 if (enabled && !was_enabled)
1561 static_key_slow_inc(&__cfs_bandwidth_used);
1562 else if (!enabled && was_enabled)
1563 static_key_slow_dec(&__cfs_bandwidth_used);
1565 #else /* HAVE_JUMP_LABEL */
1566 static bool cfs_bandwidth_used(void)
1571 void account_cfs_bandwidth_used(int enabled, int was_enabled) {}
1572 #endif /* HAVE_JUMP_LABEL */
1575 * default period for cfs group bandwidth.
1576 * default: 0.1s, units: nanoseconds
1578 static inline u64 default_cfs_period(void)
1580 return 100000000ULL;
1583 static inline u64 sched_cfs_bandwidth_slice(void)
1585 return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
1589 * Replenish runtime according to assigned quota and update expiration time.
1590 * We use sched_clock_cpu directly instead of rq->clock to avoid adding
1591 * additional synchronization around rq->lock.
1593 * requires cfs_b->lock
1595 void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
1599 if (cfs_b->quota == RUNTIME_INF)
1602 now = sched_clock_cpu(smp_processor_id());
1603 cfs_b->runtime = cfs_b->quota;
1604 cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period);
1607 static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
1609 return &tg->cfs_bandwidth;
1612 /* returns 0 on failure to allocate runtime */
1613 static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
1615 struct task_group *tg = cfs_rq->tg;
1616 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
1617 u64 amount = 0, min_amount, expires;
1619 /* note: this is a positive sum as runtime_remaining <= 0 */
1620 min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining;
1622 raw_spin_lock(&cfs_b->lock);
1623 if (cfs_b->quota == RUNTIME_INF)
1624 amount = min_amount;
1627 * If the bandwidth pool has become inactive, then at least one
1628 * period must have elapsed since the last consumption.
1629 * Refresh the global state and ensure bandwidth timer becomes
1632 if (!cfs_b->timer_active) {
1633 __refill_cfs_bandwidth_runtime(cfs_b);
1634 __start_cfs_bandwidth(cfs_b);
1637 if (cfs_b->runtime > 0) {
1638 amount = min(cfs_b->runtime, min_amount);
1639 cfs_b->runtime -= amount;
1643 expires = cfs_b->runtime_expires;
1644 raw_spin_unlock(&cfs_b->lock);
1646 cfs_rq->runtime_remaining += amount;
1648 * we may have advanced our local expiration to account for allowed
1649 * spread between our sched_clock and the one on which runtime was
1652 if ((s64)(expires - cfs_rq->runtime_expires) > 0)
1653 cfs_rq->runtime_expires = expires;
1655 return cfs_rq->runtime_remaining > 0;
1659 * Note: This depends on the synchronization provided by sched_clock and the
1660 * fact that rq->clock snapshots this value.
1662 static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq)
1664 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
1665 struct rq *rq = rq_of(cfs_rq);
1667 /* if the deadline is ahead of our clock, nothing to do */
1668 if (likely((s64)(rq->clock - cfs_rq->runtime_expires) < 0))
1671 if (cfs_rq->runtime_remaining < 0)
1675 * If the local deadline has passed we have to consider the
1676 * possibility that our sched_clock is 'fast' and the global deadline
1677 * has not truly expired.
1679 * Fortunately we can check determine whether this the case by checking
1680 * whether the global deadline has advanced.
1683 if ((s64)(cfs_rq->runtime_expires - cfs_b->runtime_expires) >= 0) {
1684 /* extend local deadline, drift is bounded above by 2 ticks */
1685 cfs_rq->runtime_expires += TICK_NSEC;
1687 /* global deadline is ahead, expiration has passed */
1688 cfs_rq->runtime_remaining = 0;
1692 static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
1693 unsigned long delta_exec)
1695 /* dock delta_exec before expiring quota (as it could span periods) */
1696 cfs_rq->runtime_remaining -= delta_exec;
1697 expire_cfs_rq_runtime(cfs_rq);
1699 if (likely(cfs_rq->runtime_remaining > 0))
1703 * if we're unable to extend our runtime we resched so that the active
1704 * hierarchy can be throttled
1706 if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
1707 resched_task(rq_of(cfs_rq)->curr);
1710 static __always_inline
1711 void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec)
1713 if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
1716 __account_cfs_rq_runtime(cfs_rq, delta_exec);
1719 static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
1721 return cfs_bandwidth_used() && cfs_rq->throttled;
1724 /* check whether cfs_rq, or any parent, is throttled */
1725 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
1727 return cfs_bandwidth_used() && cfs_rq->throttle_count;
1731 * Ensure that neither of the group entities corresponding to src_cpu or
1732 * dest_cpu are members of a throttled hierarchy when performing group
1733 * load-balance operations.
1735 static inline int throttled_lb_pair(struct task_group *tg,
1736 int src_cpu, int dest_cpu)
1738 struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
1740 src_cfs_rq = tg->cfs_rq[src_cpu];
1741 dest_cfs_rq = tg->cfs_rq[dest_cpu];
1743 return throttled_hierarchy(src_cfs_rq) ||
1744 throttled_hierarchy(dest_cfs_rq);
1747 /* updated child weight may affect parent so we have to do this bottom up */
1748 static int tg_unthrottle_up(struct task_group *tg, void *data)
1750 struct rq *rq = data;
1751 struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
1753 cfs_rq->throttle_count--;
1755 if (!cfs_rq->throttle_count) {
1756 u64 delta = rq->clock_task - cfs_rq->load_stamp;
1758 /* leaving throttled state, advance shares averaging windows */
1759 cfs_rq->load_stamp += delta;
1760 cfs_rq->load_last += delta;
1762 /* update entity weight now that we are on_rq again */
1763 update_cfs_shares(cfs_rq);
1770 static int tg_throttle_down(struct task_group *tg, void *data)
1772 struct rq *rq = data;
1773 struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
1775 /* group is entering throttled state, record last load */
1776 if (!cfs_rq->throttle_count)
1777 update_cfs_load(cfs_rq, 0);
1778 cfs_rq->throttle_count++;
1783 static void throttle_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;
1788 long task_delta, dequeue = 1;
1790 se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
1792 /* account load preceding throttle */
1794 walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
1797 task_delta = cfs_rq->h_nr_running;
1798 for_each_sched_entity(se) {
1799 struct cfs_rq *qcfs_rq = cfs_rq_of(se);
1800 /* throttled entity or throttle-on-deactivate */
1805 dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
1806 qcfs_rq->h_nr_running -= task_delta;
1808 if (qcfs_rq->load.weight)
1813 rq->nr_running -= task_delta;
1815 cfs_rq->throttled = 1;
1816 cfs_rq->throttled_timestamp = rq->clock;
1817 raw_spin_lock(&cfs_b->lock);
1818 list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
1819 raw_spin_unlock(&cfs_b->lock);
1822 void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
1824 struct rq *rq = rq_of(cfs_rq);
1825 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
1826 struct sched_entity *se;
1830 se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
1832 cfs_rq->throttled = 0;
1833 raw_spin_lock(&cfs_b->lock);
1834 cfs_b->throttled_time += rq->clock - cfs_rq->throttled_timestamp;
1835 list_del_rcu(&cfs_rq->throttled_list);
1836 raw_spin_unlock(&cfs_b->lock);
1837 cfs_rq->throttled_timestamp = 0;
1839 update_rq_clock(rq);
1840 /* update hierarchical throttle state */
1841 walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
1843 if (!cfs_rq->load.weight)
1846 task_delta = cfs_rq->h_nr_running;
1847 for_each_sched_entity(se) {
1851 cfs_rq = cfs_rq_of(se);
1853 enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);
1854 cfs_rq->h_nr_running += task_delta;
1856 if (cfs_rq_throttled(cfs_rq))
1861 rq->nr_running += task_delta;
1863 /* determine whether we need to wake up potentially idle cpu */
1864 if (rq->curr == rq->idle && rq->cfs.nr_running)
1865 resched_task(rq->curr);
1868 static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
1869 u64 remaining, u64 expires)
1871 struct cfs_rq *cfs_rq;
1872 u64 runtime = remaining;
1875 list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
1877 struct rq *rq = rq_of(cfs_rq);
1879 raw_spin_lock(&rq->lock);
1880 if (!cfs_rq_throttled(cfs_rq))
1883 runtime = -cfs_rq->runtime_remaining + 1;
1884 if (runtime > remaining)
1885 runtime = remaining;
1886 remaining -= runtime;
1888 cfs_rq->runtime_remaining += runtime;
1889 cfs_rq->runtime_expires = expires;
1891 /* we check whether we're throttled above */
1892 if (cfs_rq->runtime_remaining > 0)
1893 unthrottle_cfs_rq(cfs_rq);
1896 raw_spin_unlock(&rq->lock);
1907 * Responsible for refilling a task_group's bandwidth and unthrottling its
1908 * cfs_rqs as appropriate. If there has been no activity within the last
1909 * period the timer is deactivated until scheduling resumes; cfs_b->idle is
1910 * used to track this state.
1912 static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
1914 u64 runtime, runtime_expires;
1915 int idle = 1, throttled;
1917 raw_spin_lock(&cfs_b->lock);
1918 /* no need to continue the timer with no bandwidth constraint */
1919 if (cfs_b->quota == RUNTIME_INF)
1922 throttled = !list_empty(&cfs_b->throttled_cfs_rq);
1923 /* idle depends on !throttled (for the case of a large deficit) */
1924 idle = cfs_b->idle && !throttled;
1925 cfs_b->nr_periods += overrun;
1927 /* if we're going inactive then everything else can be deferred */
1931 __refill_cfs_bandwidth_runtime(cfs_b);
1934 /* mark as potentially idle for the upcoming period */
1939 /* account preceding periods in which throttling occurred */
1940 cfs_b->nr_throttled += overrun;
1943 * There are throttled entities so we must first use the new bandwidth
1944 * to unthrottle them before making it generally available. This
1945 * ensures that all existing debts will be paid before a new cfs_rq is
1948 runtime = cfs_b->runtime;
1949 runtime_expires = cfs_b->runtime_expires;
1953 * This check is repeated as we are holding onto the new bandwidth
1954 * while we unthrottle. This can potentially race with an unthrottled
1955 * group trying to acquire new bandwidth from the global pool.
1957 while (throttled && runtime > 0) {
1958 raw_spin_unlock(&cfs_b->lock);
1959 /* we can't nest cfs_b->lock while distributing bandwidth */
1960 runtime = distribute_cfs_runtime(cfs_b, runtime,
1962 raw_spin_lock(&cfs_b->lock);
1964 throttled = !list_empty(&cfs_b->throttled_cfs_rq);
1967 /* return (any) remaining runtime */
1968 cfs_b->runtime = runtime;
1970 * While we are ensured activity in the period following an
1971 * unthrottle, this also covers the case in which the new bandwidth is
1972 * insufficient to cover the existing bandwidth deficit. (Forcing the
1973 * timer to remain active while there are any throttled entities.)
1978 cfs_b->timer_active = 0;
1979 raw_spin_unlock(&cfs_b->lock);
1984 /* a cfs_rq won't donate quota below this amount */
1985 static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
1986 /* minimum remaining period time to redistribute slack quota */
1987 static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
1988 /* how long we wait to gather additional slack before distributing */
1989 static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
1991 /* are we near the end of the current quota period? */
1992 static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
1994 struct hrtimer *refresh_timer = &cfs_b->period_timer;
1997 /* if the call-back is running a quota refresh is already occurring */
1998 if (hrtimer_callback_running(refresh_timer))
2001 /* is a quota refresh about to occur? */
2002 remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
2003 if (remaining < min_expire)
2009 static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
2011 u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
2013 /* if there's a quota refresh soon don't bother with slack */
2014 if (runtime_refresh_within(cfs_b, min_left))
2017 start_bandwidth_timer(&cfs_b->slack_timer,
2018 ns_to_ktime(cfs_bandwidth_slack_period));
2021 /* we know any runtime found here is valid as update_curr() precedes return */
2022 static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2024 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2025 s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
2027 if (slack_runtime <= 0)
2030 raw_spin_lock(&cfs_b->lock);
2031 if (cfs_b->quota != RUNTIME_INF &&
2032 cfs_rq->runtime_expires == cfs_b->runtime_expires) {
2033 cfs_b->runtime += slack_runtime;
2035 /* we are under rq->lock, defer unthrottling using a timer */
2036 if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
2037 !list_empty(&cfs_b->throttled_cfs_rq))
2038 start_cfs_slack_bandwidth(cfs_b);
2040 raw_spin_unlock(&cfs_b->lock);
2042 /* even if it's not valid for return we don't want to try again */
2043 cfs_rq->runtime_remaining -= slack_runtime;
2046 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2048 if (!cfs_bandwidth_used())
2051 if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
2054 __return_cfs_rq_runtime(cfs_rq);
2058 * This is done with a timer (instead of inline with bandwidth return) since
2059 * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
2061 static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
2063 u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
2066 /* confirm we're still not at a refresh boundary */
2067 if (runtime_refresh_within(cfs_b, min_bandwidth_expiration))
2070 raw_spin_lock(&cfs_b->lock);
2071 if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) {
2072 runtime = cfs_b->runtime;
2075 expires = cfs_b->runtime_expires;
2076 raw_spin_unlock(&cfs_b->lock);
2081 runtime = distribute_cfs_runtime(cfs_b, runtime, expires);
2083 raw_spin_lock(&cfs_b->lock);
2084 if (expires == cfs_b->runtime_expires)
2085 cfs_b->runtime = runtime;
2086 raw_spin_unlock(&cfs_b->lock);
2090 * When a group wakes up we want to make sure that its quota is not already
2091 * expired/exceeded, otherwise it may be allowed to steal additional ticks of
2092 * runtime as update_curr() throttling can not not trigger until it's on-rq.
2094 static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
2096 if (!cfs_bandwidth_used())
2099 /* an active group must be handled by the update_curr()->put() path */
2100 if (!cfs_rq->runtime_enabled || cfs_rq->curr)
2103 /* ensure the group is not already throttled */
2104 if (cfs_rq_throttled(cfs_rq))
2107 /* update runtime allocation */
2108 account_cfs_rq_runtime(cfs_rq, 0);
2109 if (cfs_rq->runtime_remaining <= 0)
2110 throttle_cfs_rq(cfs_rq);
2113 /* conditionally throttle active cfs_rq's from put_prev_entity() */
2114 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2116 if (!cfs_bandwidth_used())
2119 if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
2123 * it's possible for a throttled entity to be forced into a running
2124 * state (e.g. set_curr_task), in this case we're finished.
2126 if (cfs_rq_throttled(cfs_rq))
2129 throttle_cfs_rq(cfs_rq);
2132 static inline u64 default_cfs_period(void);
2133 static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun);
2134 static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b);
2136 static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
2138 struct cfs_bandwidth *cfs_b =
2139 container_of(timer, struct cfs_bandwidth, slack_timer);
2140 do_sched_cfs_slack_timer(cfs_b);
2142 return HRTIMER_NORESTART;
2145 static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
2147 struct cfs_bandwidth *cfs_b =
2148 container_of(timer, struct cfs_bandwidth, period_timer);
2154 now = hrtimer_cb_get_time(timer);
2155 overrun = hrtimer_forward(timer, now, cfs_b->period);
2160 idle = do_sched_cfs_period_timer(cfs_b, overrun);
2163 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
2166 void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2168 raw_spin_lock_init(&cfs_b->lock);
2170 cfs_b->quota = RUNTIME_INF;
2171 cfs_b->period = ns_to_ktime(default_cfs_period());
2173 INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
2174 hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
2175 cfs_b->period_timer.function = sched_cfs_period_timer;
2176 hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
2177 cfs_b->slack_timer.function = sched_cfs_slack_timer;
2180 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2182 cfs_rq->runtime_enabled = 0;
2183 INIT_LIST_HEAD(&cfs_rq->throttled_list);
2186 /* requires cfs_b->lock, may release to reprogram timer */
2187 void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2190 * The timer may be active because we're trying to set a new bandwidth
2191 * period or because we're racing with the tear-down path
2192 * (timer_active==0 becomes visible before the hrtimer call-back
2193 * terminates). In either case we ensure that it's re-programmed
2195 while (unlikely(hrtimer_active(&cfs_b->period_timer))) {
2196 raw_spin_unlock(&cfs_b->lock);
2197 /* ensure cfs_b->lock is available while we wait */
2198 hrtimer_cancel(&cfs_b->period_timer);
2200 raw_spin_lock(&cfs_b->lock);
2201 /* if someone else restarted the timer then we're done */
2202 if (cfs_b->timer_active)
2206 cfs_b->timer_active = 1;
2207 start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period);
2210 static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2212 hrtimer_cancel(&cfs_b->period_timer);
2213 hrtimer_cancel(&cfs_b->slack_timer);
2216 static void unthrottle_offline_cfs_rqs(struct rq *rq)
2218 struct cfs_rq *cfs_rq;
2220 for_each_leaf_cfs_rq(rq, cfs_rq) {
2221 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2223 if (!cfs_rq->runtime_enabled)
2227 * clock_task is not advancing so we just need to make sure
2228 * there's some valid quota amount
2230 cfs_rq->runtime_remaining = cfs_b->quota;
2231 if (cfs_rq_throttled(cfs_rq))
2232 unthrottle_cfs_rq(cfs_rq);
2236 #else /* CONFIG_CFS_BANDWIDTH */
2237 static __always_inline
2238 void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec) {}
2239 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2240 static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
2241 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2243 static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
2248 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
2253 static inline int throttled_lb_pair(struct task_group *tg,
2254 int src_cpu, int dest_cpu)
2259 void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
2261 #ifdef CONFIG_FAIR_GROUP_SCHED
2262 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2265 static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
2269 static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
2270 static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
2272 #endif /* CONFIG_CFS_BANDWIDTH */
2274 /**************************************************
2275 * CFS operations on tasks:
2278 #ifdef CONFIG_SCHED_HRTICK
2279 static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
2281 struct sched_entity *se = &p->se;
2282 struct cfs_rq *cfs_rq = cfs_rq_of(se);
2284 WARN_ON(task_rq(p) != rq);
2286 if (cfs_rq->nr_running > 1) {
2287 u64 slice = sched_slice(cfs_rq, se);
2288 u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
2289 s64 delta = slice - ran;
2298 * Don't schedule slices shorter than 10000ns, that just
2299 * doesn't make sense. Rely on vruntime for fairness.
2302 delta = max_t(s64, 10000LL, delta);
2304 hrtick_start(rq, delta);
2309 * called from enqueue/dequeue and updates the hrtick when the
2310 * current task is from our class and nr_running is low enough
2313 static void hrtick_update(struct rq *rq)
2315 struct task_struct *curr = rq->curr;
2317 if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class)
2320 if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
2321 hrtick_start_fair(rq, curr);
2323 #else /* !CONFIG_SCHED_HRTICK */
2325 hrtick_start_fair(struct rq *rq, struct task_struct *p)
2329 static inline void hrtick_update(struct rq *rq)
2335 * The enqueue_task method is called before nr_running is
2336 * increased. Here we update the fair scheduling stats and
2337 * then put the task into the rbtree:
2340 enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
2342 struct cfs_rq *cfs_rq;
2343 struct sched_entity *se = &p->se;
2345 for_each_sched_entity(se) {
2348 cfs_rq = cfs_rq_of(se);
2349 enqueue_entity(cfs_rq, se, flags);
2352 * end evaluation on encountering a throttled cfs_rq
2354 * note: in the case of encountering a throttled cfs_rq we will
2355 * post the final h_nr_running increment below.
2357 if (cfs_rq_throttled(cfs_rq))
2359 cfs_rq->h_nr_running++;
2361 flags = ENQUEUE_WAKEUP;
2364 for_each_sched_entity(se) {
2365 cfs_rq = cfs_rq_of(se);
2366 cfs_rq->h_nr_running++;
2368 if (cfs_rq_throttled(cfs_rq))
2371 update_cfs_load(cfs_rq, 0);
2372 update_cfs_shares(cfs_rq);
2380 static void set_next_buddy(struct sched_entity *se);
2383 * The dequeue_task method is called before nr_running is
2384 * decreased. We remove the task from the rbtree and
2385 * update the fair scheduling stats:
2387 static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
2389 struct cfs_rq *cfs_rq;
2390 struct sched_entity *se = &p->se;
2391 int task_sleep = flags & DEQUEUE_SLEEP;
2393 for_each_sched_entity(se) {
2394 cfs_rq = cfs_rq_of(se);
2395 dequeue_entity(cfs_rq, se, flags);
2398 * end evaluation on encountering a throttled cfs_rq
2400 * note: in the case of encountering a throttled cfs_rq we will
2401 * post the final h_nr_running decrement below.
2403 if (cfs_rq_throttled(cfs_rq))
2405 cfs_rq->h_nr_running--;
2407 /* Don't dequeue parent if it has other entities besides us */
2408 if (cfs_rq->load.weight) {
2410 * Bias pick_next to pick a task from this cfs_rq, as
2411 * p is sleeping when it is within its sched_slice.
2413 if (task_sleep && parent_entity(se))
2414 set_next_buddy(parent_entity(se));
2416 /* avoid re-evaluating load for this entity */
2417 se = parent_entity(se);
2420 flags |= DEQUEUE_SLEEP;
2423 for_each_sched_entity(se) {
2424 cfs_rq = cfs_rq_of(se);
2425 cfs_rq->h_nr_running--;
2427 if (cfs_rq_throttled(cfs_rq))
2430 update_cfs_load(cfs_rq, 0);
2431 update_cfs_shares(cfs_rq);
2440 /* Used instead of source_load when we know the type == 0 */
2441 static unsigned long weighted_cpuload(const int cpu)
2443 return cpu_rq(cpu)->load.weight;
2447 * Return a low guess at the load of a migration-source cpu weighted
2448 * according to the scheduling class and "nice" value.
2450 * We want to under-estimate the load of migration sources, to
2451 * balance conservatively.
2453 static unsigned long source_load(int cpu, int type)
2455 struct rq *rq = cpu_rq(cpu);
2456 unsigned long total = weighted_cpuload(cpu);
2458 if (type == 0 || !sched_feat(LB_BIAS))
2461 return min(rq->cpu_load[type-1], total);
2465 * Return a high guess at the load of a migration-target cpu weighted
2466 * according to the scheduling class and "nice" value.
2468 static unsigned long target_load(int cpu, int type)
2470 struct rq *rq = cpu_rq(cpu);
2471 unsigned long total = weighted_cpuload(cpu);
2473 if (type == 0 || !sched_feat(LB_BIAS))
2476 return max(rq->cpu_load[type-1], total);
2479 static unsigned long power_of(int cpu)
2481 return cpu_rq(cpu)->cpu_power;
2484 static unsigned long cpu_avg_load_per_task(int cpu)
2486 struct rq *rq = cpu_rq(cpu);
2487 unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
2490 return rq->load.weight / nr_running;
2496 static void task_waking_fair(struct task_struct *p)
2498 struct sched_entity *se = &p->se;
2499 struct cfs_rq *cfs_rq = cfs_rq_of(se);
2502 #ifndef CONFIG_64BIT
2503 u64 min_vruntime_copy;
2506 min_vruntime_copy = cfs_rq->min_vruntime_copy;
2508 min_vruntime = cfs_rq->min_vruntime;
2509 } while (min_vruntime != min_vruntime_copy);
2511 min_vruntime = cfs_rq->min_vruntime;
2514 se->vruntime -= min_vruntime;
2517 #ifdef CONFIG_FAIR_GROUP_SCHED
2519 * effective_load() calculates the load change as seen from the root_task_group
2521 * Adding load to a group doesn't make a group heavier, but can cause movement
2522 * of group shares between cpus. Assuming the shares were perfectly aligned one
2523 * can calculate the shift in shares.
2525 * Calculate the effective load difference if @wl is added (subtracted) to @tg
2526 * on this @cpu and results in a total addition (subtraction) of @wg to the
2527 * total group weight.
2529 * Given a runqueue weight distribution (rw_i) we can compute a shares
2530 * distribution (s_i) using:
2532 * s_i = rw_i / \Sum rw_j (1)
2534 * Suppose we have 4 CPUs and our @tg is a direct child of the root group and
2535 * has 7 equal weight tasks, distributed as below (rw_i), with the resulting
2536 * shares distribution (s_i):
2538 * rw_i = { 2, 4, 1, 0 }
2539 * s_i = { 2/7, 4/7, 1/7, 0 }
2541 * As per wake_affine() we're interested in the load of two CPUs (the CPU the
2542 * task used to run on and the CPU the waker is running on), we need to
2543 * compute the effect of waking a task on either CPU and, in case of a sync
2544 * wakeup, compute the effect of the current task going to sleep.
2546 * So for a change of @wl to the local @cpu with an overall group weight change
2547 * of @wl we can compute the new shares distribution (s'_i) using:
2549 * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2)
2551 * Suppose we're interested in CPUs 0 and 1, and want to compute the load
2552 * differences in waking a task to CPU 0. The additional task changes the
2553 * weight and shares distributions like:
2555 * rw'_i = { 3, 4, 1, 0 }
2556 * s'_i = { 3/8, 4/8, 1/8, 0 }
2558 * We can then compute the difference in effective weight by using:
2560 * dw_i = S * (s'_i - s_i) (3)
2562 * Where 'S' is the group weight as seen by its parent.
2564 * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7)
2565 * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 -
2566 * 4/7) times the weight of the group.
2568 static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
2570 struct sched_entity *se = tg->se[cpu];
2572 if (!tg->parent) /* the trivial, non-cgroup case */
2575 for_each_sched_entity(se) {
2581 * W = @wg + \Sum rw_j
2583 W = wg + calc_tg_weight(tg, se->my_q);
2588 w = se->my_q->load.weight + wl;
2591 * wl = S * s'_i; see (2)
2594 wl = (w * tg->shares) / W;
2599 * Per the above, wl is the new se->load.weight value; since
2600 * those are clipped to [MIN_SHARES, ...) do so now. See
2601 * calc_cfs_shares().
2603 if (wl < MIN_SHARES)
2607 * wl = dw_i = S * (s'_i - s_i); see (3)
2609 wl -= se->load.weight;
2612 * Recursively apply this logic to all parent groups to compute
2613 * the final effective load change on the root group. Since
2614 * only the @tg group gets extra weight, all parent groups can
2615 * only redistribute existing shares. @wl is the shift in shares
2616 * resulting from this level per the above.
2625 static inline unsigned long effective_load(struct task_group *tg, int cpu,
2626 unsigned long wl, unsigned long wg)
2633 static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
2635 s64 this_load, load;
2636 int idx, this_cpu, prev_cpu;
2637 unsigned long tl_per_task;
2638 struct task_group *tg;
2639 unsigned long weight;
2643 this_cpu = smp_processor_id();
2644 prev_cpu = task_cpu(p);
2645 load = source_load(prev_cpu, idx);
2646 this_load = target_load(this_cpu, idx);
2649 * If sync wakeup then subtract the (maximum possible)
2650 * effect of the currently running task from the load
2651 * of the current CPU:
2654 tg = task_group(current);
2655 weight = current->se.load.weight;
2657 this_load += effective_load(tg, this_cpu, -weight, -weight);
2658 load += effective_load(tg, prev_cpu, 0, -weight);
2662 weight = p->se.load.weight;
2665 * In low-load situations, where prev_cpu is idle and this_cpu is idle
2666 * due to the sync cause above having dropped this_load to 0, we'll
2667 * always have an imbalance, but there's really nothing you can do
2668 * about that, so that's good too.
2670 * Otherwise check if either cpus are near enough in load to allow this
2671 * task to be woken on this_cpu.
2673 if (this_load > 0) {
2674 s64 this_eff_load, prev_eff_load;
2676 this_eff_load = 100;
2677 this_eff_load *= power_of(prev_cpu);
2678 this_eff_load *= this_load +
2679 effective_load(tg, this_cpu, weight, weight);
2681 prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2;
2682 prev_eff_load *= power_of(this_cpu);
2683 prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight);
2685 balanced = this_eff_load <= prev_eff_load;
2690 * If the currently running task will sleep within
2691 * a reasonable amount of time then attract this newly
2694 if (sync && balanced)
2697 schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
2698 tl_per_task = cpu_avg_load_per_task(this_cpu);
2701 (this_load <= load &&
2702 this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
2704 * This domain has SD_WAKE_AFFINE and
2705 * p is cache cold in this domain, and
2706 * there is no bad imbalance.
2708 schedstat_inc(sd, ttwu_move_affine);
2709 schedstat_inc(p, se.statistics.nr_wakeups_affine);
2717 * find_idlest_group finds and returns the least busy CPU group within the
2720 static struct sched_group *
2721 find_idlest_group(struct sched_domain *sd, struct task_struct *p,
2722 int this_cpu, int load_idx)
2724 struct sched_group *idlest = NULL, *group = sd->groups;
2725 unsigned long min_load = ULONG_MAX, this_load = 0;
2726 int imbalance = 100 + (sd->imbalance_pct-100)/2;
2729 unsigned long load, avg_load;
2733 /* Skip over this group if it has no CPUs allowed */
2734 if (!cpumask_intersects(sched_group_cpus(group),
2735 tsk_cpus_allowed(p)))
2738 local_group = cpumask_test_cpu(this_cpu,
2739 sched_group_cpus(group));
2741 /* Tally up the load of all CPUs in the group */
2744 for_each_cpu(i, sched_group_cpus(group)) {
2745 /* Bias balancing toward cpus of our domain */
2747 load = source_load(i, load_idx);
2749 load = target_load(i, load_idx);
2754 /* Adjust by relative CPU power of the group */
2755 avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power;
2758 this_load = avg_load;
2759 } else if (avg_load < min_load) {
2760 min_load = avg_load;
2763 } while (group = group->next, group != sd->groups);
2765 if (!idlest || 100*this_load < imbalance*min_load)
2771 * find_idlest_cpu - find the idlest cpu among the cpus in group.
2774 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
2776 unsigned long load, min_load = ULONG_MAX;
2780 /* Traverse only the allowed CPUs */
2781 for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) {
2782 load = weighted_cpuload(i);
2784 if (load < min_load || (load == min_load && i == this_cpu)) {
2794 * Try and locate an idle CPU in the sched_domain.
2796 static int select_idle_sibling(struct task_struct *p, int target)
2798 int cpu = smp_processor_id();
2799 int prev_cpu = task_cpu(p);
2800 struct sched_domain *sd;
2801 struct sched_group *sg;
2805 * If the task is going to be woken-up on this cpu and if it is
2806 * already idle, then it is the right target.
2808 if (target == cpu && idle_cpu(cpu))
2812 * If the task is going to be woken-up on the cpu where it previously
2813 * ran and if it is currently idle, then it the right target.
2815 if (target == prev_cpu && idle_cpu(prev_cpu))
2819 * Otherwise, iterate the domains and find an elegible idle cpu.
2821 sd = rcu_dereference(per_cpu(sd_llc, target));
2822 for_each_lower_domain(sd) {
2825 if (!cpumask_intersects(sched_group_cpus(sg),
2826 tsk_cpus_allowed(p)))
2829 for_each_cpu(i, sched_group_cpus(sg)) {
2834 target = cpumask_first_and(sched_group_cpus(sg),
2835 tsk_cpus_allowed(p));
2839 } while (sg != sd->groups);
2846 * sched_balance_self: balance the current task (running on cpu) in domains
2847 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
2850 * Balance, ie. select the least loaded group.
2852 * Returns the target CPU number, or the same CPU if no balancing is needed.
2854 * preempt must be disabled.
2857 select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
2859 struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
2860 int cpu = smp_processor_id();
2861 int prev_cpu = task_cpu(p);
2863 int want_affine = 0;
2864 int sync = wake_flags & WF_SYNC;
2866 if (p->nr_cpus_allowed == 1)
2869 if (sd_flag & SD_BALANCE_WAKE) {
2870 if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
2876 for_each_domain(cpu, tmp) {
2877 if (!(tmp->flags & SD_LOAD_BALANCE))
2881 * If both cpu and prev_cpu are part of this domain,
2882 * cpu is a valid SD_WAKE_AFFINE target.
2884 if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
2885 cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
2890 if (tmp->flags & sd_flag)
2895 if (cpu != prev_cpu && wake_affine(affine_sd, p, sync))
2898 new_cpu = select_idle_sibling(p, prev_cpu);
2903 int load_idx = sd->forkexec_idx;
2904 struct sched_group *group;
2907 if (!(sd->flags & sd_flag)) {
2912 if (sd_flag & SD_BALANCE_WAKE)
2913 load_idx = sd->wake_idx;
2915 group = find_idlest_group(sd, p, cpu, load_idx);
2921 new_cpu = find_idlest_cpu(group, p, cpu);
2922 if (new_cpu == -1 || new_cpu == cpu) {
2923 /* Now try balancing at a lower domain level of cpu */
2928 /* Now try balancing at a lower domain level of new_cpu */
2930 weight = sd->span_weight;
2932 for_each_domain(cpu, tmp) {
2933 if (weight <= tmp->span_weight)
2935 if (tmp->flags & sd_flag)
2938 /* while loop will break here if sd == NULL */
2945 #endif /* CONFIG_SMP */
2947 static unsigned long
2948 wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
2950 unsigned long gran = sysctl_sched_wakeup_granularity;
2953 * Since its curr running now, convert the gran from real-time
2954 * to virtual-time in his units.
2956 * By using 'se' instead of 'curr' we penalize light tasks, so
2957 * they get preempted easier. That is, if 'se' < 'curr' then
2958 * the resulting gran will be larger, therefore penalizing the
2959 * lighter, if otoh 'se' > 'curr' then the resulting gran will
2960 * be smaller, again penalizing the lighter task.
2962 * This is especially important for buddies when the leftmost
2963 * task is higher priority than the buddy.
2965 return calc_delta_fair(gran, se);
2969 * Should 'se' preempt 'curr'.
2983 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
2985 s64 gran, vdiff = curr->vruntime - se->vruntime;
2990 gran = wakeup_gran(curr, se);
2997 static void set_last_buddy(struct sched_entity *se)
2999 if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
3002 for_each_sched_entity(se)
3003 cfs_rq_of(se)->last = se;
3006 static void set_next_buddy(struct sched_entity *se)
3008 if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
3011 for_each_sched_entity(se)
3012 cfs_rq_of(se)->next = se;
3015 static void set_skip_buddy(struct sched_entity *se)
3017 for_each_sched_entity(se)
3018 cfs_rq_of(se)->skip = se;
3022 * Preempt the current task with a newly woken task if needed:
3024 static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
3026 struct task_struct *curr = rq->curr;
3027 struct sched_entity *se = &curr->se, *pse = &p->se;
3028 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
3029 int scale = cfs_rq->nr_running >= sched_nr_latency;
3030 int next_buddy_marked = 0;
3032 if (unlikely(se == pse))
3036 * This is possible from callers such as move_task(), in which we
3037 * unconditionally check_prempt_curr() after an enqueue (which may have
3038 * lead to a throttle). This both saves work and prevents false
3039 * next-buddy nomination below.
3041 if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
3044 if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
3045 set_next_buddy(pse);
3046 next_buddy_marked = 1;
3050 * We can come here with TIF_NEED_RESCHED already set from new task
3053 * Note: this also catches the edge-case of curr being in a throttled
3054 * group (e.g. via set_curr_task), since update_curr() (in the
3055 * enqueue of curr) will have resulted in resched being set. This
3056 * prevents us from potentially nominating it as a false LAST_BUDDY
3059 if (test_tsk_need_resched(curr))
3062 /* Idle tasks are by definition preempted by non-idle tasks. */
3063 if (unlikely(curr->policy == SCHED_IDLE) &&
3064 likely(p->policy != SCHED_IDLE))
3068 * Batch and idle tasks do not preempt non-idle tasks (their preemption
3069 * is driven by the tick):
3071 if (unlikely(p->policy != SCHED_NORMAL))
3074 find_matching_se(&se, &pse);
3075 update_curr(cfs_rq_of(se));
3077 if (wakeup_preempt_entity(se, pse) == 1) {
3079 * Bias pick_next to pick the sched entity that is
3080 * triggering this preemption.
3082 if (!next_buddy_marked)
3083 set_next_buddy(pse);
3092 * Only set the backward buddy when the current task is still
3093 * on the rq. This can happen when a wakeup gets interleaved
3094 * with schedule on the ->pre_schedule() or idle_balance()
3095 * point, either of which can * drop the rq lock.
3097 * Also, during early boot the idle thread is in the fair class,
3098 * for obvious reasons its a bad idea to schedule back to it.
3100 if (unlikely(!se->on_rq || curr == rq->idle))
3103 if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
3107 static struct task_struct *pick_next_task_fair(struct rq *rq)
3109 struct task_struct *p;
3110 struct cfs_rq *cfs_rq = &rq->cfs;
3111 struct sched_entity *se;
3113 if (!cfs_rq->nr_running)
3117 se = pick_next_entity(cfs_rq);
3118 set_next_entity(cfs_rq, se);
3119 cfs_rq = group_cfs_rq(se);
3123 if (hrtick_enabled(rq))
3124 hrtick_start_fair(rq, p);
3130 * Account for a descheduled task:
3132 static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
3134 struct sched_entity *se = &prev->se;
3135 struct cfs_rq *cfs_rq;
3137 for_each_sched_entity(se) {
3138 cfs_rq = cfs_rq_of(se);
3139 put_prev_entity(cfs_rq, se);
3144 * sched_yield() is very simple
3146 * The magic of dealing with the ->skip buddy is in pick_next_entity.
3148 static void yield_task_fair(struct rq *rq)
3150 struct task_struct *curr = rq->curr;
3151 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
3152 struct sched_entity *se = &curr->se;
3155 * Are we the only task in the tree?
3157 if (unlikely(rq->nr_running == 1))
3160 clear_buddies(cfs_rq, se);
3162 if (curr->policy != SCHED_BATCH) {
3163 update_rq_clock(rq);
3165 * Update run-time statistics of the 'current'.
3167 update_curr(cfs_rq);
3169 * Tell update_rq_clock() that we've just updated,
3170 * so we don't do microscopic update in schedule()
3171 * and double the fastpath cost.
3173 rq->skip_clock_update = 1;
3179 static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt)
3181 struct sched_entity *se = &p->se;
3183 /* throttled hierarchies are not runnable */
3184 if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
3187 /* Tell the scheduler that we'd really like pse to run next. */
3190 yield_task_fair(rq);
3196 /**************************************************
3197 * Fair scheduling class load-balancing methods:
3200 static unsigned long __read_mostly max_load_balance_interval = HZ/10;
3202 #define LBF_ALL_PINNED 0x01
3203 #define LBF_NEED_BREAK 0x02
3204 #define LBF_SOME_PINNED 0x04
3207 struct sched_domain *sd;
3215 struct cpumask *dst_grpmask;
3217 enum cpu_idle_type idle;
3219 /* The set of CPUs under consideration for load-balancing */
3220 struct cpumask *cpus;
3225 unsigned int loop_break;
3226 unsigned int loop_max;
3230 * move_task - move a task from one runqueue to another runqueue.
3231 * Both runqueues must be locked.
3233 static void move_task(struct task_struct *p, struct lb_env *env)
3235 deactivate_task(env->src_rq, p, 0);
3236 set_task_cpu(p, env->dst_cpu);
3237 activate_task(env->dst_rq, p, 0);
3238 check_preempt_curr(env->dst_rq, p, 0);
3242 * Is this task likely cache-hot:
3245 task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
3249 if (p->sched_class != &fair_sched_class)
3252 if (unlikely(p->policy == SCHED_IDLE))
3256 * Buddy candidates are cache hot:
3258 if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running &&
3259 (&p->se == cfs_rq_of(&p->se)->next ||
3260 &p->se == cfs_rq_of(&p->se)->last))
3263 if (sysctl_sched_migration_cost == -1)
3265 if (sysctl_sched_migration_cost == 0)
3268 delta = now - p->se.exec_start;
3270 return delta < (s64)sysctl_sched_migration_cost;
3274 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
3277 int can_migrate_task(struct task_struct *p, struct lb_env *env)
3279 int tsk_cache_hot = 0;
3281 * We do not migrate tasks that are:
3282 * 1) running (obviously), or
3283 * 2) cannot be migrated to this CPU due to cpus_allowed, or
3284 * 3) are cache-hot on their current CPU.
3286 if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
3289 schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
3292 * Remember if this task can be migrated to any other cpu in
3293 * our sched_group. We may want to revisit it if we couldn't
3294 * meet load balance goals by pulling other tasks on src_cpu.
3296 * Also avoid computing new_dst_cpu if we have already computed
3297 * one in current iteration.
3299 if (!env->dst_grpmask || (env->flags & LBF_SOME_PINNED))
3302 new_dst_cpu = cpumask_first_and(env->dst_grpmask,
3303 tsk_cpus_allowed(p));
3304 if (new_dst_cpu < nr_cpu_ids) {
3305 env->flags |= LBF_SOME_PINNED;
3306 env->new_dst_cpu = new_dst_cpu;
3311 /* Record that we found atleast one task that could run on dst_cpu */
3312 env->flags &= ~LBF_ALL_PINNED;
3314 if (task_running(env->src_rq, p)) {
3315 schedstat_inc(p, se.statistics.nr_failed_migrations_running);
3320 * Aggressive migration if:
3321 * 1) task is cache cold, or
3322 * 2) too many balance attempts have failed.
3325 tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
3326 if (!tsk_cache_hot ||
3327 env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
3328 #ifdef CONFIG_SCHEDSTATS
3329 if (tsk_cache_hot) {
3330 schedstat_inc(env->sd, lb_hot_gained[env->idle]);
3331 schedstat_inc(p, se.statistics.nr_forced_migrations);
3337 if (tsk_cache_hot) {
3338 schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
3345 * move_one_task tries to move exactly one task from busiest to this_rq, as
3346 * part of active balancing operations within "domain".
3347 * Returns 1 if successful and 0 otherwise.
3349 * Called with both runqueues locked.
3351 static int move_one_task(struct lb_env *env)
3353 struct task_struct *p, *n;
3355 list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
3356 if (throttled_lb_pair(task_group(p), env->src_rq->cpu, env->dst_cpu))
3359 if (!can_migrate_task(p, env))
3364 * Right now, this is only the second place move_task()
3365 * is called, so we can safely collect move_task()
3366 * stats here rather than inside move_task().
3368 schedstat_inc(env->sd, lb_gained[env->idle]);
3374 static unsigned long task_h_load(struct task_struct *p);
3376 static const unsigned int sched_nr_migrate_break = 32;
3379 * move_tasks tries to move up to imbalance weighted load from busiest to
3380 * this_rq, as part of a balancing operation within domain "sd".
3381 * Returns 1 if successful and 0 otherwise.
3383 * Called with both runqueues locked.
3385 static int move_tasks(struct lb_env *env)
3387 struct list_head *tasks = &env->src_rq->cfs_tasks;
3388 struct task_struct *p;
3392 if (env->imbalance <= 0)
3395 while (!list_empty(tasks)) {
3396 p = list_first_entry(tasks, struct task_struct, se.group_node);
3399 /* We've more or less seen every task there is, call it quits */
3400 if (env->loop > env->loop_max)
3403 /* take a breather every nr_migrate tasks */
3404 if (env->loop > env->loop_break) {
3405 env->loop_break += sched_nr_migrate_break;
3406 env->flags |= LBF_NEED_BREAK;
3410 if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
3413 load = task_h_load(p);
3415 if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed)
3418 if ((load / 2) > env->imbalance)
3421 if (!can_migrate_task(p, env))
3426 env->imbalance -= load;
3428 #ifdef CONFIG_PREEMPT
3430 * NEWIDLE balancing is a source of latency, so preemptible
3431 * kernels will stop after the first task is pulled to minimize
3432 * the critical section.
3434 if (env->idle == CPU_NEWLY_IDLE)
3439 * We only want to steal up to the prescribed amount of
3442 if (env->imbalance <= 0)
3447 list_move_tail(&p->se.group_node, tasks);
3451 * Right now, this is one of only two places move_task() is called,
3452 * so we can safely collect move_task() stats here rather than
3453 * inside move_task().
3455 schedstat_add(env->sd, lb_gained[env->idle], pulled);
3460 #ifdef CONFIG_FAIR_GROUP_SCHED
3462 * update tg->load_weight by folding this cpu's load_avg
3464 static int update_shares_cpu(struct task_group *tg, int cpu)
3466 struct cfs_rq *cfs_rq;
3467 unsigned long flags;
3474 cfs_rq = tg->cfs_rq[cpu];
3476 raw_spin_lock_irqsave(&rq->lock, flags);
3478 update_rq_clock(rq);
3479 update_cfs_load(cfs_rq, 1);
3482 * We need to update shares after updating tg->load_weight in
3483 * order to adjust the weight of groups with long running tasks.
3485 update_cfs_shares(cfs_rq);
3487 raw_spin_unlock_irqrestore(&rq->lock, flags);
3492 static void update_shares(int cpu)
3494 struct cfs_rq *cfs_rq;
3495 struct rq *rq = cpu_rq(cpu);
3499 * Iterates the task_group tree in a bottom up fashion, see
3500 * list_add_leaf_cfs_rq() for details.
3502 for_each_leaf_cfs_rq(rq, cfs_rq) {
3503 /* throttled entities do not contribute to load */
3504 if (throttled_hierarchy(cfs_rq))
3507 update_shares_cpu(cfs_rq->tg, cpu);
3513 * Compute the cpu's hierarchical load factor for each task group.
3514 * This needs to be done in a top-down fashion because the load of a child
3515 * group is a fraction of its parents load.
3517 static int tg_load_down(struct task_group *tg, void *data)
3520 long cpu = (long)data;
3523 load = cpu_rq(cpu)->load.weight;
3525 load = tg->parent->cfs_rq[cpu]->h_load;
3526 load *= tg->se[cpu]->load.weight;
3527 load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
3530 tg->cfs_rq[cpu]->h_load = load;
3535 static void update_h_load(long cpu)
3537 struct rq *rq = cpu_rq(cpu);
3538 unsigned long now = jiffies;
3540 if (rq->h_load_throttle == now)
3543 rq->h_load_throttle = now;
3546 walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
3550 static unsigned long task_h_load(struct task_struct *p)
3552 struct cfs_rq *cfs_rq = task_cfs_rq(p);
3555 load = p->se.load.weight;
3556 load = div_u64(load * cfs_rq->h_load, cfs_rq->load.weight + 1);
3561 static inline void update_shares(int cpu)
3565 static inline void update_h_load(long cpu)
3569 static unsigned long task_h_load(struct task_struct *p)
3571 return p->se.load.weight;
3575 /********** Helpers for find_busiest_group ************************/
3577 * sd_lb_stats - Structure to store the statistics of a sched_domain
3578 * during load balancing.
3580 struct sd_lb_stats {
3581 struct sched_group *busiest; /* Busiest group in this sd */
3582 struct sched_group *this; /* Local group in this sd */
3583 unsigned long total_load; /* Total load of all groups in sd */
3584 unsigned long total_pwr; /* Total power of all groups in sd */
3585 unsigned long avg_load; /* Average load across all groups in sd */
3587 /** Statistics of this group */
3588 unsigned long this_load;
3589 unsigned long this_load_per_task;
3590 unsigned long this_nr_running;
3591 unsigned long this_has_capacity;
3592 unsigned int this_idle_cpus;
3594 /* Statistics of the busiest group */
3595 unsigned int busiest_idle_cpus;
3596 unsigned long max_load;
3597 unsigned long busiest_load_per_task;
3598 unsigned long busiest_nr_running;
3599 unsigned long busiest_group_capacity;
3600 unsigned long busiest_has_capacity;
3601 unsigned int busiest_group_weight;
3603 int group_imb; /* Is there imbalance in this sd */
3607 * sg_lb_stats - stats of a sched_group required for load_balancing
3609 struct sg_lb_stats {
3610 unsigned long avg_load; /*Avg load across the CPUs of the group */
3611 unsigned long group_load; /* Total load over the CPUs of the group */
3612 unsigned long sum_nr_running; /* Nr tasks running in the group */
3613 unsigned long sum_weighted_load; /* Weighted load of group's tasks */
3614 unsigned long group_capacity;
3615 unsigned long idle_cpus;
3616 unsigned long group_weight;
3617 int group_imb; /* Is there an imbalance in the group ? */
3618 int group_has_capacity; /* Is there extra capacity in the group? */
3622 * get_sd_load_idx - Obtain the load index for a given sched domain.
3623 * @sd: The sched_domain whose load_idx is to be obtained.
3624 * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
3626 static inline int get_sd_load_idx(struct sched_domain *sd,
3627 enum cpu_idle_type idle)
3633 load_idx = sd->busy_idx;
3636 case CPU_NEWLY_IDLE:
3637 load_idx = sd->newidle_idx;
3640 load_idx = sd->idle_idx;
3647 unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
3649 return SCHED_POWER_SCALE;
3652 unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
3654 return default_scale_freq_power(sd, cpu);
3657 unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
3659 unsigned long weight = sd->span_weight;
3660 unsigned long smt_gain = sd->smt_gain;
3667 unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
3669 return default_scale_smt_power(sd, cpu);
3672 unsigned long scale_rt_power(int cpu)
3674 struct rq *rq = cpu_rq(cpu);
3675 u64 total, available, age_stamp, avg;
3678 * Since we're reading these variables without serialization make sure
3679 * we read them once before doing sanity checks on them.
3681 age_stamp = ACCESS_ONCE(rq->age_stamp);
3682 avg = ACCESS_ONCE(rq->rt_avg);
3684 total = sched_avg_period() + (rq->clock - age_stamp);
3686 if (unlikely(total < avg)) {
3687 /* Ensures that power won't end up being negative */
3690 available = total - avg;
3693 if (unlikely((s64)total < SCHED_POWER_SCALE))
3694 total = SCHED_POWER_SCALE;
3696 total >>= SCHED_POWER_SHIFT;
3698 return div_u64(available, total);
3701 static void update_cpu_power(struct sched_domain *sd, int cpu)
3703 unsigned long weight = sd->span_weight;
3704 unsigned long power = SCHED_POWER_SCALE;
3705 struct sched_group *sdg = sd->groups;
3707 if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
3708 if (sched_feat(ARCH_POWER))
3709 power *= arch_scale_smt_power(sd, cpu);
3711 power *= default_scale_smt_power(sd, cpu);
3713 power >>= SCHED_POWER_SHIFT;
3716 sdg->sgp->power_orig = power;
3718 if (sched_feat(ARCH_POWER))
3719 power *= arch_scale_freq_power(sd, cpu);
3721 power *= default_scale_freq_power(sd, cpu);
3723 power >>= SCHED_POWER_SHIFT;
3725 power *= scale_rt_power(cpu);
3726 power >>= SCHED_POWER_SHIFT;
3731 cpu_rq(cpu)->cpu_power = power;
3732 sdg->sgp->power = power;
3735 void update_group_power(struct sched_domain *sd, int cpu)
3737 struct sched_domain *child = sd->child;
3738 struct sched_group *group, *sdg = sd->groups;
3739 unsigned long power;
3740 unsigned long interval;
3742 interval = msecs_to_jiffies(sd->balance_interval);
3743 interval = clamp(interval, 1UL, max_load_balance_interval);
3744 sdg->sgp->next_update = jiffies + interval;
3747 update_cpu_power(sd, cpu);
3753 if (child->flags & SD_OVERLAP) {
3755 * SD_OVERLAP domains cannot assume that child groups
3756 * span the current group.
3759 for_each_cpu(cpu, sched_group_cpus(sdg))
3760 power += power_of(cpu);
3763 * !SD_OVERLAP domains can assume that child groups
3764 * span the current group.
3767 group = child->groups;
3769 power += group->sgp->power;
3770 group = group->next;
3771 } while (group != child->groups);
3774 sdg->sgp->power_orig = sdg->sgp->power = power;
3778 * Try and fix up capacity for tiny siblings, this is needed when
3779 * things like SD_ASYM_PACKING need f_b_g to select another sibling
3780 * which on its own isn't powerful enough.
3782 * See update_sd_pick_busiest() and check_asym_packing().
3785 fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
3788 * Only siblings can have significantly less than SCHED_POWER_SCALE
3790 if (!(sd->flags & SD_SHARE_CPUPOWER))
3794 * If ~90% of the cpu_power is still there, we're good.
3796 if (group->sgp->power * 32 > group->sgp->power_orig * 29)
3803 * update_sg_lb_stats - Update sched_group's statistics for load balancing.
3804 * @env: The load balancing environment.
3805 * @group: sched_group whose statistics are to be updated.
3806 * @load_idx: Load index of sched_domain of this_cpu for load calc.
3807 * @local_group: Does group contain this_cpu.
3808 * @balance: Should we balance.
3809 * @sgs: variable to hold the statistics for this group.
3811 static inline void update_sg_lb_stats(struct lb_env *env,
3812 struct sched_group *group, int load_idx,
3813 int local_group, int *balance, struct sg_lb_stats *sgs)
3815 unsigned long nr_running, max_nr_running, min_nr_running;
3816 unsigned long load, max_cpu_load, min_cpu_load;
3817 unsigned int balance_cpu = -1, first_idle_cpu = 0;
3818 unsigned long avg_load_per_task = 0;
3822 balance_cpu = group_balance_cpu(group);
3824 /* Tally up the load of all CPUs in the group */
3826 min_cpu_load = ~0UL;
3828 min_nr_running = ~0UL;
3830 for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
3831 struct rq *rq = cpu_rq(i);
3833 nr_running = rq->nr_running;
3835 /* Bias balancing toward cpus of our domain */
3837 if (idle_cpu(i) && !first_idle_cpu &&
3838 cpumask_test_cpu(i, sched_group_mask(group))) {
3843 load = target_load(i, load_idx);
3845 load = source_load(i, load_idx);
3846 if (load > max_cpu_load)
3847 max_cpu_load = load;
3848 if (min_cpu_load > load)
3849 min_cpu_load = load;
3851 if (nr_running > max_nr_running)
3852 max_nr_running = nr_running;
3853 if (min_nr_running > nr_running)
3854 min_nr_running = nr_running;
3857 sgs->group_load += load;
3858 sgs->sum_nr_running += nr_running;
3859 sgs->sum_weighted_load += weighted_cpuload(i);
3865 * First idle cpu or the first cpu(busiest) in this sched group
3866 * is eligible for doing load balancing at this and above
3867 * domains. In the newly idle case, we will allow all the cpu's
3868 * to do the newly idle load balance.
3871 if (env->idle != CPU_NEWLY_IDLE) {
3872 if (balance_cpu != env->dst_cpu) {
3876 update_group_power(env->sd, env->dst_cpu);
3877 } else if (time_after_eq(jiffies, group->sgp->next_update))
3878 update_group_power(env->sd, env->dst_cpu);
3881 /* Adjust by relative CPU power of the group */
3882 sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;
3885 * Consider the group unbalanced when the imbalance is larger
3886 * than the average weight of a task.
3888 * APZ: with cgroup the avg task weight can vary wildly and
3889 * might not be a suitable number - should we keep a
3890 * normalized nr_running number somewhere that negates
3893 if (sgs->sum_nr_running)
3894 avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
3896 if ((max_cpu_load - min_cpu_load) >= avg_load_per_task &&
3897 (max_nr_running - min_nr_running) > 1)
3900 sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
3902 if (!sgs->group_capacity)
3903 sgs->group_capacity = fix_small_capacity(env->sd, group);
3904 sgs->group_weight = group->group_weight;
3906 if (sgs->group_capacity > sgs->sum_nr_running)
3907 sgs->group_has_capacity = 1;
3911 * update_sd_pick_busiest - return 1 on busiest group
3912 * @env: The load balancing environment.
3913 * @sds: sched_domain statistics
3914 * @sg: sched_group candidate to be checked for being the busiest
3915 * @sgs: sched_group statistics
3917 * Determine if @sg is a busier group than the previously selected
3920 static bool update_sd_pick_busiest(struct lb_env *env,
3921 struct sd_lb_stats *sds,
3922 struct sched_group *sg,
3923 struct sg_lb_stats *sgs)
3925 if (sgs->avg_load <= sds->max_load)
3928 if (sgs->sum_nr_running > sgs->group_capacity)
3935 * ASYM_PACKING needs to move all the work to the lowest
3936 * numbered CPUs in the group, therefore mark all groups
3937 * higher than ourself as busy.
3939 if ((env->sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running &&
3940 env->dst_cpu < group_first_cpu(sg)) {
3944 if (group_first_cpu(sds->busiest) > group_first_cpu(sg))
3952 * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
3953 * @env: The load balancing environment.
3954 * @balance: Should we balance.
3955 * @sds: variable to hold the statistics for this sched_domain.
3957 static inline void update_sd_lb_stats(struct lb_env *env,
3958 int *balance, struct sd_lb_stats *sds)
3960 struct sched_domain *child = env->sd->child;
3961 struct sched_group *sg = env->sd->groups;
3962 struct sg_lb_stats sgs;
3963 int load_idx, prefer_sibling = 0;
3965 if (child && child->flags & SD_PREFER_SIBLING)
3968 load_idx = get_sd_load_idx(env->sd, env->idle);
3973 local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg));
3974 memset(&sgs, 0, sizeof(sgs));
3975 update_sg_lb_stats(env, sg, load_idx, local_group, balance, &sgs);
3977 if (local_group && !(*balance))
3980 sds->total_load += sgs.group_load;
3981 sds->total_pwr += sg->sgp->power;
3984 * In case the child domain prefers tasks go to siblings
3985 * first, lower the sg capacity to one so that we'll try
3986 * and move all the excess tasks away. We lower the capacity
3987 * of a group only if the local group has the capacity to fit
3988 * these excess tasks, i.e. nr_running < group_capacity. The
3989 * extra check prevents the case where you always pull from the
3990 * heaviest group when it is already under-utilized (possible
3991 * with a large weight task outweighs the tasks on the system).
3993 if (prefer_sibling && !local_group && sds->this_has_capacity)
3994 sgs.group_capacity = min(sgs.group_capacity, 1UL);
3997 sds->this_load = sgs.avg_load;
3999 sds->this_nr_running = sgs.sum_nr_running;
4000 sds->this_load_per_task = sgs.sum_weighted_load;
4001 sds->this_has_capacity = sgs.group_has_capacity;
4002 sds->this_idle_cpus = sgs.idle_cpus;
4003 } else if (update_sd_pick_busiest(env, sds, sg, &sgs)) {
4004 sds->max_load = sgs.avg_load;
4006 sds->busiest_nr_running = sgs.sum_nr_running;
4007 sds->busiest_idle_cpus = sgs.idle_cpus;
4008 sds->busiest_group_capacity = sgs.group_capacity;
4009 sds->busiest_load_per_task = sgs.sum_weighted_load;
4010 sds->busiest_has_capacity = sgs.group_has_capacity;
4011 sds->busiest_group_weight = sgs.group_weight;
4012 sds->group_imb = sgs.group_imb;
4016 } while (sg != env->sd->groups);
4020 * check_asym_packing - Check to see if the group is packed into the
4023 * This is primarily intended to used at the sibling level. Some
4024 * cores like POWER7 prefer to use lower numbered SMT threads. In the
4025 * case of POWER7, it can move to lower SMT modes only when higher
4026 * threads are idle. When in lower SMT modes, the threads will
4027 * perform better since they share less core resources. Hence when we
4028 * have idle threads, we want them to be the higher ones.
4030 * This packing function is run on idle threads. It checks to see if
4031 * the busiest CPU in this domain (core in the P7 case) has a higher
4032 * CPU number than the packing function is being run on. Here we are
4033 * assuming lower CPU number will be equivalent to lower a SMT thread
4036 * Returns 1 when packing is required and a task should be moved to
4037 * this CPU. The amount of the imbalance is returned in *imbalance.
4039 * @env: The load balancing environment.
4040 * @sds: Statistics of the sched_domain which is to be packed
4042 static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
4046 if (!(env->sd->flags & SD_ASYM_PACKING))
4052 busiest_cpu = group_first_cpu(sds->busiest);
4053 if (env->dst_cpu > busiest_cpu)
4056 env->imbalance = DIV_ROUND_CLOSEST(
4057 sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE);
4063 * fix_small_imbalance - Calculate the minor imbalance that exists
4064 * amongst the groups of a sched_domain, during
4066 * @env: The load balancing environment.
4067 * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
4070 void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
4072 unsigned long tmp, pwr_now = 0, pwr_move = 0;
4073 unsigned int imbn = 2;
4074 unsigned long scaled_busy_load_per_task;
4076 if (sds->this_nr_running) {
4077 sds->this_load_per_task /= sds->this_nr_running;
4078 if (sds->busiest_load_per_task >
4079 sds->this_load_per_task)
4082 sds->this_load_per_task =
4083 cpu_avg_load_per_task(env->dst_cpu);
4086 scaled_busy_load_per_task = sds->busiest_load_per_task
4087 * SCHED_POWER_SCALE;
4088 scaled_busy_load_per_task /= sds->busiest->sgp->power;
4090 if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
4091 (scaled_busy_load_per_task * imbn)) {
4092 env->imbalance = sds->busiest_load_per_task;
4097 * OK, we don't have enough imbalance to justify moving tasks,
4098 * however we may be able to increase total CPU power used by
4102 pwr_now += sds->busiest->sgp->power *
4103 min(sds->busiest_load_per_task, sds->max_load);
4104 pwr_now += sds->this->sgp->power *
4105 min(sds->this_load_per_task, sds->this_load);
4106 pwr_now /= SCHED_POWER_SCALE;
4108 /* Amount of load we'd subtract */
4109 tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
4110 sds->busiest->sgp->power;
4111 if (sds->max_load > tmp)
4112 pwr_move += sds->busiest->sgp->power *
4113 min(sds->busiest_load_per_task, sds->max_load - tmp);
4115 /* Amount of load we'd add */
4116 if (sds->max_load * sds->busiest->sgp->power <
4117 sds->busiest_load_per_task * SCHED_POWER_SCALE)
4118 tmp = (sds->max_load * sds->busiest->sgp->power) /
4119 sds->this->sgp->power;
4121 tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
4122 sds->this->sgp->power;
4123 pwr_move += sds->this->sgp->power *
4124 min(sds->this_load_per_task, sds->this_load + tmp);
4125 pwr_move /= SCHED_POWER_SCALE;
4127 /* Move if we gain throughput */
4128 if (pwr_move > pwr_now)
4129 env->imbalance = sds->busiest_load_per_task;
4133 * calculate_imbalance - Calculate the amount of imbalance present within the
4134 * groups of a given sched_domain during load balance.
4135 * @env: load balance environment
4136 * @sds: statistics of the sched_domain whose imbalance is to be calculated.
4138 static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
4140 unsigned long max_pull, load_above_capacity = ~0UL;
4142 sds->busiest_load_per_task /= sds->busiest_nr_running;
4143 if (sds->group_imb) {
4144 sds->busiest_load_per_task =
4145 min(sds->busiest_load_per_task, sds->avg_load);
4149 * In the presence of smp nice balancing, certain scenarios can have
4150 * max load less than avg load(as we skip the groups at or below
4151 * its cpu_power, while calculating max_load..)
4153 if (sds->max_load < sds->avg_load) {
4155 return fix_small_imbalance(env, sds);
4158 if (!sds->group_imb) {
4160 * Don't want to pull so many tasks that a group would go idle.
4162 load_above_capacity = (sds->busiest_nr_running -
4163 sds->busiest_group_capacity);
4165 load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
4167 load_above_capacity /= sds->busiest->sgp->power;
4171 * We're trying to get all the cpus to the average_load, so we don't
4172 * want to push ourselves above the average load, nor do we wish to
4173 * reduce the max loaded cpu below the average load. At the same time,
4174 * we also don't want to reduce the group load below the group capacity
4175 * (so that we can implement power-savings policies etc). Thus we look
4176 * for the minimum possible imbalance.
4177 * Be careful of negative numbers as they'll appear as very large values
4178 * with unsigned longs.
4180 max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);
4182 /* How much load to actually move to equalise the imbalance */
4183 env->imbalance = min(max_pull * sds->busiest->sgp->power,
4184 (sds->avg_load - sds->this_load) * sds->this->sgp->power)
4185 / SCHED_POWER_SCALE;
4188 * if *imbalance is less than the average load per runnable task
4189 * there is no guarantee that any tasks will be moved so we'll have
4190 * a think about bumping its value to force at least one task to be
4193 if (env->imbalance < sds->busiest_load_per_task)
4194 return fix_small_imbalance(env, sds);
4198 /******* find_busiest_group() helpers end here *********************/
4201 * find_busiest_group - Returns the busiest group within the sched_domain
4202 * if there is an imbalance. If there isn't an imbalance, and
4203 * the user has opted for power-savings, it returns a group whose
4204 * CPUs can be put to idle by rebalancing those tasks elsewhere, if
4205 * such a group exists.
4207 * Also calculates the amount of weighted load which should be moved
4208 * to restore balance.
4210 * @env: The load balancing environment.
4211 * @balance: Pointer to a variable indicating if this_cpu
4212 * is the appropriate cpu to perform load balancing at this_level.
4214 * Returns: - the busiest group if imbalance exists.
4215 * - If no imbalance and user has opted for power-savings balance,
4216 * return the least loaded group whose CPUs can be
4217 * put to idle by rebalancing its tasks onto our group.
4219 static struct sched_group *
4220 find_busiest_group(struct lb_env *env, int *balance)
4222 struct sd_lb_stats sds;
4224 memset(&sds, 0, sizeof(sds));
4227 * Compute the various statistics relavent for load balancing at
4230 update_sd_lb_stats(env, balance, &sds);
4233 * this_cpu is not the appropriate cpu to perform load balancing at
4239 if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) &&
4240 check_asym_packing(env, &sds))
4243 /* There is no busy sibling group to pull tasks from */
4244 if (!sds.busiest || sds.busiest_nr_running == 0)
4247 sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
4250 * If the busiest group is imbalanced the below checks don't
4251 * work because they assumes all things are equal, which typically
4252 * isn't true due to cpus_allowed constraints and the like.
4257 /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
4258 if (env->idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
4259 !sds.busiest_has_capacity)
4263 * If the local group is more busy than the selected busiest group
4264 * don't try and pull any tasks.
4266 if (sds.this_load >= sds.max_load)
4270 * Don't pull any tasks if this group is already above the domain
4273 if (sds.this_load >= sds.avg_load)
4276 if (env->idle == CPU_IDLE) {
4278 * This cpu is idle. If the busiest group load doesn't
4279 * have more tasks than the number of available cpu's and
4280 * there is no imbalance between this and busiest group
4281 * wrt to idle cpu's, it is balanced.
4283 if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) &&
4284 sds.busiest_nr_running <= sds.busiest_group_weight)
4288 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
4289 * imbalance_pct to be conservative.
4291 if (100 * sds.max_load <= env->sd->imbalance_pct * sds.this_load)
4296 /* Looks like there is an imbalance. Compute it */
4297 calculate_imbalance(env, &sds);
4307 * find_busiest_queue - find the busiest runqueue among the cpus in group.
4309 static struct rq *find_busiest_queue(struct lb_env *env,
4310 struct sched_group *group)
4312 struct rq *busiest = NULL, *rq;
4313 unsigned long max_load = 0;
4316 for_each_cpu(i, sched_group_cpus(group)) {
4317 unsigned long power = power_of(i);
4318 unsigned long capacity = DIV_ROUND_CLOSEST(power,
4323 capacity = fix_small_capacity(env->sd, group);
4325 if (!cpumask_test_cpu(i, env->cpus))
4329 wl = weighted_cpuload(i);
4332 * When comparing with imbalance, use weighted_cpuload()
4333 * which is not scaled with the cpu power.
4335 if (capacity && rq->nr_running == 1 && wl > env->imbalance)
4339 * For the load comparisons with the other cpu's, consider
4340 * the weighted_cpuload() scaled with the cpu power, so that
4341 * the load can be moved away from the cpu that is potentially
4342 * running at a lower capacity.
4344 wl = (wl * SCHED_POWER_SCALE) / power;
4346 if (wl > max_load) {
4356 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
4357 * so long as it is large enough.
4359 #define MAX_PINNED_INTERVAL 512
4361 /* Working cpumask for load_balance and load_balance_newidle. */
4362 DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
4364 static int need_active_balance(struct lb_env *env)
4366 struct sched_domain *sd = env->sd;
4368 if (env->idle == CPU_NEWLY_IDLE) {
4371 * ASYM_PACKING needs to force migrate tasks from busy but
4372 * higher numbered CPUs in order to pack all tasks in the
4373 * lowest numbered CPUs.
4375 if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu)
4379 return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
4382 static int active_load_balance_cpu_stop(void *data);
4385 * Check this_cpu to ensure it is balanced within domain. Attempt to move
4386 * tasks if there is an imbalance.
4388 static int load_balance(int this_cpu, struct rq *this_rq,
4389 struct sched_domain *sd, enum cpu_idle_type idle,
4392 int ld_moved, cur_ld_moved, active_balance = 0;
4393 int lb_iterations, max_lb_iterations;
4394 struct sched_group *group;
4396 unsigned long flags;
4397 struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
4399 struct lb_env env = {
4401 .dst_cpu = this_cpu,
4403 .dst_grpmask = sched_group_cpus(sd->groups),
4405 .loop_break = sched_nr_migrate_break,
4409 cpumask_copy(cpus, cpu_active_mask);
4410 max_lb_iterations = cpumask_weight(env.dst_grpmask);
4412 schedstat_inc(sd, lb_count[idle]);
4415 group = find_busiest_group(&env, balance);
4421 schedstat_inc(sd, lb_nobusyg[idle]);
4425 busiest = find_busiest_queue(&env, group);
4427 schedstat_inc(sd, lb_nobusyq[idle]);
4431 BUG_ON(busiest == env.dst_rq);
4433 schedstat_add(sd, lb_imbalance[idle], env.imbalance);
4437 if (busiest->nr_running > 1) {
4439 * Attempt to move tasks. If find_busiest_group has found
4440 * an imbalance but busiest->nr_running <= 1, the group is
4441 * still unbalanced. ld_moved simply stays zero, so it is
4442 * correctly treated as an imbalance.
4444 env.flags |= LBF_ALL_PINNED;
4445 env.src_cpu = busiest->cpu;
4446 env.src_rq = busiest;
4447 env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running);
4449 update_h_load(env.src_cpu);
4451 local_irq_save(flags);
4452 double_rq_lock(env.dst_rq, busiest);
4455 * cur_ld_moved - load moved in current iteration
4456 * ld_moved - cumulative load moved across iterations
4458 cur_ld_moved = move_tasks(&env);
4459 ld_moved += cur_ld_moved;
4460 double_rq_unlock(env.dst_rq, busiest);
4461 local_irq_restore(flags);
4463 if (env.flags & LBF_NEED_BREAK) {
4464 env.flags &= ~LBF_NEED_BREAK;
4469 * some other cpu did the load balance for us.
4471 if (cur_ld_moved && env.dst_cpu != smp_processor_id())
4472 resched_cpu(env.dst_cpu);
4475 * Revisit (affine) tasks on src_cpu that couldn't be moved to
4476 * us and move them to an alternate dst_cpu in our sched_group
4477 * where they can run. The upper limit on how many times we
4478 * iterate on same src_cpu is dependent on number of cpus in our
4481 * This changes load balance semantics a bit on who can move
4482 * load to a given_cpu. In addition to the given_cpu itself
4483 * (or a ilb_cpu acting on its behalf where given_cpu is
4484 * nohz-idle), we now have balance_cpu in a position to move
4485 * load to given_cpu. In rare situations, this may cause
4486 * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
4487 * _independently_ and at _same_ time to move some load to
4488 * given_cpu) causing exceess load to be moved to given_cpu.
4489 * This however should not happen so much in practice and
4490 * moreover subsequent load balance cycles should correct the
4491 * excess load moved.
4493 if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0 &&
4494 lb_iterations++ < max_lb_iterations) {
4496 env.dst_rq = cpu_rq(env.new_dst_cpu);
4497 env.dst_cpu = env.new_dst_cpu;
4498 env.flags &= ~LBF_SOME_PINNED;
4500 env.loop_break = sched_nr_migrate_break;
4502 * Go back to "more_balance" rather than "redo" since we
4503 * need to continue with same src_cpu.
4508 /* All tasks on this runqueue were pinned by CPU affinity */
4509 if (unlikely(env.flags & LBF_ALL_PINNED)) {
4510 cpumask_clear_cpu(cpu_of(busiest), cpus);
4511 if (!cpumask_empty(cpus)) {
4513 env.loop_break = sched_nr_migrate_break;
4521 schedstat_inc(sd, lb_failed[idle]);
4523 * Increment the failure counter only on periodic balance.
4524 * We do not want newidle balance, which can be very
4525 * frequent, pollute the failure counter causing
4526 * excessive cache_hot migrations and active balances.
4528 if (idle != CPU_NEWLY_IDLE)
4529 sd->nr_balance_failed++;
4531 if (need_active_balance(&env)) {
4532 raw_spin_lock_irqsave(&busiest->lock, flags);
4534 /* don't kick the active_load_balance_cpu_stop,
4535 * if the curr task on busiest cpu can't be
4538 if (!cpumask_test_cpu(this_cpu,
4539 tsk_cpus_allowed(busiest->curr))) {
4540 raw_spin_unlock_irqrestore(&busiest->lock,
4542 env.flags |= LBF_ALL_PINNED;
4543 goto out_one_pinned;
4547 * ->active_balance synchronizes accesses to
4548 * ->active_balance_work. Once set, it's cleared
4549 * only after active load balance is finished.
4551 if (!busiest->active_balance) {
4552 busiest->active_balance = 1;
4553 busiest->push_cpu = this_cpu;
4556 raw_spin_unlock_irqrestore(&busiest->lock, flags);
4558 if (active_balance) {
4559 stop_one_cpu_nowait(cpu_of(busiest),
4560 active_load_balance_cpu_stop, busiest,
4561 &busiest->active_balance_work);
4565 * We've kicked active balancing, reset the failure
4568 sd->nr_balance_failed = sd->cache_nice_tries+1;
4571 sd->nr_balance_failed = 0;
4573 if (likely(!active_balance)) {
4574 /* We were unbalanced, so reset the balancing interval */
4575 sd->balance_interval = sd->min_interval;
4578 * If we've begun active balancing, start to back off. This
4579 * case may not be covered by the all_pinned logic if there
4580 * is only 1 task on the busy runqueue (because we don't call
4583 if (sd->balance_interval < sd->max_interval)
4584 sd->balance_interval *= 2;
4590 schedstat_inc(sd, lb_balanced[idle]);
4592 sd->nr_balance_failed = 0;
4595 /* tune up the balancing interval */
4596 if (((env.flags & LBF_ALL_PINNED) &&
4597 sd->balance_interval < MAX_PINNED_INTERVAL) ||
4598 (sd->balance_interval < sd->max_interval))
4599 sd->balance_interval *= 2;
4607 * idle_balance is called by schedule() if this_cpu is about to become
4608 * idle. Attempts to pull tasks from other CPUs.
4610 void idle_balance(int this_cpu, struct rq *this_rq)
4612 struct sched_domain *sd;
4613 int pulled_task = 0;
4614 unsigned long next_balance = jiffies + HZ;
4616 this_rq->idle_stamp = this_rq->clock;
4618 if (this_rq->avg_idle < sysctl_sched_migration_cost)
4622 * Drop the rq->lock, but keep IRQ/preempt disabled.
4624 raw_spin_unlock(&this_rq->lock);
4626 update_shares(this_cpu);
4628 for_each_domain(this_cpu, sd) {
4629 unsigned long interval;
4632 if (!(sd->flags & SD_LOAD_BALANCE))
4635 if (sd->flags & SD_BALANCE_NEWIDLE) {
4636 /* If we've pulled tasks over stop searching: */
4637 pulled_task = load_balance(this_cpu, this_rq,
4638 sd, CPU_NEWLY_IDLE, &balance);
4641 interval = msecs_to_jiffies(sd->balance_interval);
4642 if (time_after(next_balance, sd->last_balance + interval))
4643 next_balance = sd->last_balance + interval;
4645 this_rq->idle_stamp = 0;
4651 raw_spin_lock(&this_rq->lock);
4653 if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
4655 * We are going idle. next_balance may be set based on
4656 * a busy processor. So reset next_balance.
4658 this_rq->next_balance = next_balance;
4663 * active_load_balance_cpu_stop is run by cpu stopper. It pushes
4664 * running tasks off the busiest CPU onto idle CPUs. It requires at
4665 * least 1 task to be running on each physical CPU where possible, and
4666 * avoids physical / logical imbalances.
4668 static int active_load_balance_cpu_stop(void *data)
4670 struct rq *busiest_rq = data;
4671 int busiest_cpu = cpu_of(busiest_rq);
4672 int target_cpu = busiest_rq->push_cpu;
4673 struct rq *target_rq = cpu_rq(target_cpu);
4674 struct sched_domain *sd;
4676 raw_spin_lock_irq(&busiest_rq->lock);
4678 /* make sure the requested cpu hasn't gone down in the meantime */
4679 if (unlikely(busiest_cpu != smp_processor_id() ||
4680 !busiest_rq->active_balance))
4683 /* Is there any task to move? */
4684 if (busiest_rq->nr_running <= 1)
4688 * This condition is "impossible", if it occurs
4689 * we need to fix it. Originally reported by
4690 * Bjorn Helgaas on a 128-cpu setup.
4692 BUG_ON(busiest_rq == target_rq);
4694 /* move a task from busiest_rq to target_rq */
4695 double_lock_balance(busiest_rq, target_rq);
4697 /* Search for an sd spanning us and the target CPU. */
4699 for_each_domain(target_cpu, sd) {
4700 if ((sd->flags & SD_LOAD_BALANCE) &&
4701 cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
4706 struct lb_env env = {
4708 .dst_cpu = target_cpu,
4709 .dst_rq = target_rq,
4710 .src_cpu = busiest_rq->cpu,
4711 .src_rq = busiest_rq,
4715 schedstat_inc(sd, alb_count);
4717 if (move_one_task(&env))
4718 schedstat_inc(sd, alb_pushed);
4720 schedstat_inc(sd, alb_failed);
4723 double_unlock_balance(busiest_rq, target_rq);
4725 busiest_rq->active_balance = 0;
4726 raw_spin_unlock_irq(&busiest_rq->lock);
4732 * idle load balancing details
4733 * - When one of the busy CPUs notice that there may be an idle rebalancing
4734 * needed, they will kick the idle load balancer, which then does idle
4735 * load balancing for all the idle CPUs.
4738 cpumask_var_t idle_cpus_mask;
4740 unsigned long next_balance; /* in jiffy units */
4741 } nohz ____cacheline_aligned;
4743 static inline int find_new_ilb(int call_cpu)
4745 int ilb = cpumask_first(nohz.idle_cpus_mask);
4747 if (ilb < nr_cpu_ids && idle_cpu(ilb))
4754 * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
4755 * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
4756 * CPU (if there is one).
4758 static void nohz_balancer_kick(int cpu)
4762 nohz.next_balance++;
4764 ilb_cpu = find_new_ilb(cpu);
4766 if (ilb_cpu >= nr_cpu_ids)
4769 if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu)))
4772 * Use smp_send_reschedule() instead of resched_cpu().
4773 * This way we generate a sched IPI on the target cpu which
4774 * is idle. And the softirq performing nohz idle load balance
4775 * will be run before returning from the IPI.
4777 smp_send_reschedule(ilb_cpu);
4781 static inline void nohz_balance_exit_idle(int cpu)
4783 if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
4784 cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
4785 atomic_dec(&nohz.nr_cpus);
4786 clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
4790 static inline void set_cpu_sd_state_busy(void)
4792 struct sched_domain *sd;
4793 int cpu = smp_processor_id();
4795 if (!test_bit(NOHZ_IDLE, nohz_flags(cpu)))
4797 clear_bit(NOHZ_IDLE, nohz_flags(cpu));
4800 for_each_domain(cpu, sd)
4801 atomic_inc(&sd->groups->sgp->nr_busy_cpus);
4805 void set_cpu_sd_state_idle(void)
4807 struct sched_domain *sd;
4808 int cpu = smp_processor_id();
4810 if (test_bit(NOHZ_IDLE, nohz_flags(cpu)))
4812 set_bit(NOHZ_IDLE, nohz_flags(cpu));
4815 for_each_domain(cpu, sd)
4816 atomic_dec(&sd->groups->sgp->nr_busy_cpus);
4821 * This routine will record that the cpu is going idle with tick stopped.
4822 * This info will be used in performing idle load balancing in the future.
4824 void nohz_balance_enter_idle(int cpu)
4827 * If this cpu is going down, then nothing needs to be done.
4829 if (!cpu_active(cpu))
4832 if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
4835 cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
4836 atomic_inc(&nohz.nr_cpus);
4837 set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
4840 static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
4841 unsigned long action, void *hcpu)
4843 switch (action & ~CPU_TASKS_FROZEN) {
4845 nohz_balance_exit_idle(smp_processor_id());
4853 static DEFINE_SPINLOCK(balancing);
4856 * Scale the max load_balance interval with the number of CPUs in the system.
4857 * This trades load-balance latency on larger machines for less cross talk.
4859 void update_max_interval(void)
4861 max_load_balance_interval = HZ*num_online_cpus()/10;
4865 * It checks each scheduling domain to see if it is due to be balanced,
4866 * and initiates a balancing operation if so.
4868 * Balancing parameters are set up in arch_init_sched_domains.
4870 static void rebalance_domains(int cpu, enum cpu_idle_type idle)
4873 struct rq *rq = cpu_rq(cpu);
4874 unsigned long interval;
4875 struct sched_domain *sd;
4876 /* Earliest time when we have to do rebalance again */
4877 unsigned long next_balance = jiffies + 60*HZ;
4878 int update_next_balance = 0;
4884 for_each_domain(cpu, sd) {
4885 if (!(sd->flags & SD_LOAD_BALANCE))
4888 interval = sd->balance_interval;
4889 if (idle != CPU_IDLE)
4890 interval *= sd->busy_factor;
4892 /* scale ms to jiffies */
4893 interval = msecs_to_jiffies(interval);
4894 interval = clamp(interval, 1UL, max_load_balance_interval);
4896 need_serialize = sd->flags & SD_SERIALIZE;
4898 if (need_serialize) {
4899 if (!spin_trylock(&balancing))
4903 if (time_after_eq(jiffies, sd->last_balance + interval)) {
4904 if (load_balance(cpu, rq, sd, idle, &balance)) {
4906 * We've pulled tasks over so either we're no
4909 idle = CPU_NOT_IDLE;
4911 sd->last_balance = jiffies;
4914 spin_unlock(&balancing);
4916 if (time_after(next_balance, sd->last_balance + interval)) {
4917 next_balance = sd->last_balance + interval;
4918 update_next_balance = 1;
4922 * Stop the load balance at this level. There is another
4923 * CPU in our sched group which is doing load balancing more
4932 * next_balance will be updated only when there is a need.
4933 * When the cpu is attached to null domain for ex, it will not be
4936 if (likely(update_next_balance))
4937 rq->next_balance = next_balance;
4942 * In CONFIG_NO_HZ case, the idle balance kickee will do the
4943 * rebalancing for all the cpus for whom scheduler ticks are stopped.
4945 static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle)
4947 struct rq *this_rq = cpu_rq(this_cpu);
4951 if (idle != CPU_IDLE ||
4952 !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
4955 for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
4956 if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
4960 * If this cpu gets work to do, stop the load balancing
4961 * work being done for other cpus. Next load
4962 * balancing owner will pick it up.
4967 rq = cpu_rq(balance_cpu);
4969 raw_spin_lock_irq(&rq->lock);
4970 update_rq_clock(rq);
4971 update_idle_cpu_load(rq);
4972 raw_spin_unlock_irq(&rq->lock);
4974 rebalance_domains(balance_cpu, CPU_IDLE);
4976 if (time_after(this_rq->next_balance, rq->next_balance))
4977 this_rq->next_balance = rq->next_balance;
4979 nohz.next_balance = this_rq->next_balance;
4981 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu));
4985 * Current heuristic for kicking the idle load balancer in the presence
4986 * of an idle cpu is the system.
4987 * - This rq has more than one task.
4988 * - At any scheduler domain level, this cpu's scheduler group has multiple
4989 * busy cpu's exceeding the group's power.
4990 * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
4991 * domain span are idle.
4993 static inline int nohz_kick_needed(struct rq *rq, int cpu)
4995 unsigned long now = jiffies;
4996 struct sched_domain *sd;
4998 if (unlikely(idle_cpu(cpu)))
5002 * We may be recently in ticked or tickless idle mode. At the first
5003 * busy tick after returning from idle, we will update the busy stats.
5005 set_cpu_sd_state_busy();
5006 nohz_balance_exit_idle(cpu);
5009 * None are in tickless mode and hence no need for NOHZ idle load
5012 if (likely(!atomic_read(&nohz.nr_cpus)))
5015 if (time_before(now, nohz.next_balance))
5018 if (rq->nr_running >= 2)
5022 for_each_domain(cpu, sd) {
5023 struct sched_group *sg = sd->groups;
5024 struct sched_group_power *sgp = sg->sgp;
5025 int nr_busy = atomic_read(&sgp->nr_busy_cpus);
5027 if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
5028 goto need_kick_unlock;
5030 if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
5031 && (cpumask_first_and(nohz.idle_cpus_mask,
5032 sched_domain_span(sd)) < cpu))
5033 goto need_kick_unlock;
5035 if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
5047 static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { }
5051 * run_rebalance_domains is triggered when needed from the scheduler tick.
5052 * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
5054 static void run_rebalance_domains(struct softirq_action *h)
5056 int this_cpu = smp_processor_id();
5057 struct rq *this_rq = cpu_rq(this_cpu);
5058 enum cpu_idle_type idle = this_rq->idle_balance ?
5059 CPU_IDLE : CPU_NOT_IDLE;
5061 rebalance_domains(this_cpu, idle);
5064 * If this cpu has a pending nohz_balance_kick, then do the
5065 * balancing on behalf of the other idle cpus whose ticks are
5068 nohz_idle_balance(this_cpu, idle);
5071 static inline int on_null_domain(int cpu)
5073 return !rcu_dereference_sched(cpu_rq(cpu)->sd);
5077 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
5079 void trigger_load_balance(struct rq *rq, int cpu)
5081 /* Don't need to rebalance while attached to NULL domain */
5082 if (time_after_eq(jiffies, rq->next_balance) &&
5083 likely(!on_null_domain(cpu)))
5084 raise_softirq(SCHED_SOFTIRQ);
5086 if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu)))
5087 nohz_balancer_kick(cpu);
5091 static void rq_online_fair(struct rq *rq)
5096 static void rq_offline_fair(struct rq *rq)
5100 /* Ensure any throttled groups are reachable by pick_next_task */
5101 unthrottle_offline_cfs_rqs(rq);
5104 #endif /* CONFIG_SMP */
5107 * scheduler tick hitting a task of our scheduling class:
5109 static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
5111 struct cfs_rq *cfs_rq;
5112 struct sched_entity *se = &curr->se;
5114 for_each_sched_entity(se) {
5115 cfs_rq = cfs_rq_of(se);
5116 entity_tick(cfs_rq, se, queued);
5119 if (sched_feat_numa(NUMA))
5120 task_tick_numa(rq, curr);
5124 * called on fork with the child task as argument from the parent's context
5125 * - child not yet on the tasklist
5126 * - preemption disabled
5128 static void task_fork_fair(struct task_struct *p)
5130 struct cfs_rq *cfs_rq;
5131 struct sched_entity *se = &p->se, *curr;
5132 int this_cpu = smp_processor_id();
5133 struct rq *rq = this_rq();
5134 unsigned long flags;
5136 raw_spin_lock_irqsave(&rq->lock, flags);
5138 update_rq_clock(rq);
5140 cfs_rq = task_cfs_rq(current);
5141 curr = cfs_rq->curr;
5143 if (unlikely(task_cpu(p) != this_cpu)) {
5145 __set_task_cpu(p, this_cpu);
5149 update_curr(cfs_rq);
5152 se->vruntime = curr->vruntime;
5153 place_entity(cfs_rq, se, 1);
5155 if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
5157 * Upon rescheduling, sched_class::put_prev_task() will place
5158 * 'current' within the tree based on its new key value.
5160 swap(curr->vruntime, se->vruntime);
5161 resched_task(rq->curr);
5164 se->vruntime -= cfs_rq->min_vruntime;
5166 raw_spin_unlock_irqrestore(&rq->lock, flags);
5170 * Priority of the task has changed. Check to see if we preempt
5174 prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
5180 * Reschedule if we are currently running on this runqueue and
5181 * our priority decreased, or if we are not currently running on
5182 * this runqueue and our priority is higher than the current's
5184 if (rq->curr == p) {
5185 if (p->prio > oldprio)
5186 resched_task(rq->curr);
5188 check_preempt_curr(rq, p, 0);
5191 static void switched_from_fair(struct rq *rq, struct task_struct *p)
5193 struct sched_entity *se = &p->se;
5194 struct cfs_rq *cfs_rq = cfs_rq_of(se);
5197 * Ensure the task's vruntime is normalized, so that when its
5198 * switched back to the fair class the enqueue_entity(.flags=0) will
5199 * do the right thing.
5201 * If it was on_rq, then the dequeue_entity(.flags=0) will already
5202 * have normalized the vruntime, if it was !on_rq, then only when
5203 * the task is sleeping will it still have non-normalized vruntime.
5205 if (!se->on_rq && p->state != TASK_RUNNING) {
5207 * Fix up our vruntime so that the current sleep doesn't
5208 * cause 'unlimited' sleep bonus.
5210 place_entity(cfs_rq, se, 0);
5211 se->vruntime -= cfs_rq->min_vruntime;
5216 * We switched to the sched_fair class.
5218 static void switched_to_fair(struct rq *rq, struct task_struct *p)
5224 * We were most likely switched from sched_rt, so
5225 * kick off the schedule if running, otherwise just see
5226 * if we can still preempt the current task.
5229 resched_task(rq->curr);
5231 check_preempt_curr(rq, p, 0);
5234 /* Account for a task changing its policy or group.
5236 * This routine is mostly called to set cfs_rq->curr field when a task
5237 * migrates between groups/classes.
5239 static void set_curr_task_fair(struct rq *rq)
5241 struct sched_entity *se = &rq->curr->se;
5243 for_each_sched_entity(se) {
5244 struct cfs_rq *cfs_rq = cfs_rq_of(se);
5246 set_next_entity(cfs_rq, se);
5247 /* ensure bandwidth has been allocated on our new cfs_rq */
5248 account_cfs_rq_runtime(cfs_rq, 0);
5252 void init_cfs_rq(struct cfs_rq *cfs_rq)
5254 cfs_rq->tasks_timeline = RB_ROOT;
5255 cfs_rq->min_vruntime = (u64)(-(1LL << 20));
5256 #ifndef CONFIG_64BIT
5257 cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
5261 #ifdef CONFIG_FAIR_GROUP_SCHED
5262 static void task_move_group_fair(struct task_struct *p, int on_rq)
5265 * If the task was not on the rq at the time of this cgroup movement
5266 * it must have been asleep, sleeping tasks keep their ->vruntime
5267 * absolute on their old rq until wakeup (needed for the fair sleeper
5268 * bonus in place_entity()).
5270 * If it was on the rq, we've just 'preempted' it, which does convert
5271 * ->vruntime to a relative base.
5273 * Make sure both cases convert their relative position when migrating
5274 * to another cgroup's rq. This does somewhat interfere with the
5275 * fair sleeper stuff for the first placement, but who cares.
5278 * When !on_rq, vruntime of the task has usually NOT been normalized.
5279 * But there are some cases where it has already been normalized:
5281 * - Moving a forked child which is waiting for being woken up by
5282 * wake_up_new_task().
5283 * - Moving a task which has been woken up by try_to_wake_up() and
5284 * waiting for actually being woken up by sched_ttwu_pending().
5286 * To prevent boost or penalty in the new cfs_rq caused by delta
5287 * min_vruntime between the two cfs_rqs, we skip vruntime adjustment.
5289 if (!on_rq && (!p->se.sum_exec_runtime || p->state == TASK_WAKING))
5293 p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime;
5294 set_task_rq(p, task_cpu(p));
5296 p->se.vruntime += cfs_rq_of(&p->se)->min_vruntime;
5299 void free_fair_sched_group(struct task_group *tg)
5303 destroy_cfs_bandwidth(tg_cfs_bandwidth(tg));
5305 for_each_possible_cpu(i) {
5307 kfree(tg->cfs_rq[i]);
5316 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
5318 struct cfs_rq *cfs_rq;
5319 struct sched_entity *se;
5322 tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL);
5325 tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL);
5329 tg->shares = NICE_0_LOAD;
5331 init_cfs_bandwidth(tg_cfs_bandwidth(tg));
5333 for_each_possible_cpu(i) {
5334 cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
5335 GFP_KERNEL, cpu_to_node(i));
5339 se = kzalloc_node(sizeof(struct sched_entity),
5340 GFP_KERNEL, cpu_to_node(i));
5344 init_cfs_rq(cfs_rq);
5345 init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);
5356 void unregister_fair_sched_group(struct task_group *tg, int cpu)
5358 struct rq *rq = cpu_rq(cpu);
5359 unsigned long flags;
5362 * Only empty task groups can be destroyed; so we can speculatively
5363 * check on_list without danger of it being re-added.
5365 if (!tg->cfs_rq[cpu]->on_list)
5368 raw_spin_lock_irqsave(&rq->lock, flags);
5369 list_del_leaf_cfs_rq(tg->cfs_rq[cpu]);
5370 raw_spin_unlock_irqrestore(&rq->lock, flags);
5373 void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
5374 struct sched_entity *se, int cpu,
5375 struct sched_entity *parent)
5377 struct rq *rq = cpu_rq(cpu);
5382 /* allow initial update_cfs_load() to truncate */
5383 cfs_rq->load_stamp = 1;
5385 init_cfs_rq_runtime(cfs_rq);
5387 tg->cfs_rq[cpu] = cfs_rq;
5390 /* se could be NULL for root_task_group */
5395 se->cfs_rq = &rq->cfs;
5397 se->cfs_rq = parent->my_q;
5400 update_load_set(&se->load, 0);
5401 se->parent = parent;
5404 static DEFINE_MUTEX(shares_mutex);
5406 int sched_group_set_shares(struct task_group *tg, unsigned long shares)
5409 unsigned long flags;
5412 * We can't change the weight of the root cgroup.
5417 shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES));
5419 mutex_lock(&shares_mutex);
5420 if (tg->shares == shares)
5423 tg->shares = shares;
5424 for_each_possible_cpu(i) {
5425 struct rq *rq = cpu_rq(i);
5426 struct sched_entity *se;
5429 /* Propagate contribution to hierarchy */
5430 raw_spin_lock_irqsave(&rq->lock, flags);
5431 for_each_sched_entity(se)
5432 update_cfs_shares(group_cfs_rq(se));
5433 raw_spin_unlock_irqrestore(&rq->lock, flags);
5437 mutex_unlock(&shares_mutex);
5440 #else /* CONFIG_FAIR_GROUP_SCHED */
5442 void free_fair_sched_group(struct task_group *tg) { }
5444 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
5449 void unregister_fair_sched_group(struct task_group *tg, int cpu) { }
5451 #endif /* CONFIG_FAIR_GROUP_SCHED */
5454 static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
5456 struct sched_entity *se = &task->se;
5457 unsigned int rr_interval = 0;
5460 * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
5463 if (rq->cfs.load.weight)
5464 rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
5470 * All the scheduling class methods:
5472 const struct sched_class fair_sched_class = {
5473 .next = &idle_sched_class,
5474 .enqueue_task = enqueue_task_fair,
5475 .dequeue_task = dequeue_task_fair,
5476 .yield_task = yield_task_fair,
5477 .yield_to_task = yield_to_task_fair,
5479 .check_preempt_curr = check_preempt_wakeup,
5481 .pick_next_task = pick_next_task_fair,
5482 .put_prev_task = put_prev_task_fair,
5485 .select_task_rq = select_task_rq_fair,
5487 .rq_online = rq_online_fair,
5488 .rq_offline = rq_offline_fair,
5490 .task_waking = task_waking_fair,
5493 .set_curr_task = set_curr_task_fair,
5494 .task_tick = task_tick_fair,
5495 .task_fork = task_fork_fair,
5497 .prio_changed = prio_changed_fair,
5498 .switched_from = switched_from_fair,
5499 .switched_to = switched_to_fair,
5501 .get_rr_interval = get_rr_interval_fair,
5503 #ifdef CONFIG_FAIR_GROUP_SCHED
5504 .task_move_group = task_move_group_fair,
5508 #ifdef CONFIG_SCHED_DEBUG
5509 void print_cfs_stats(struct seq_file *m, int cpu)
5511 struct cfs_rq *cfs_rq;
5514 for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
5515 print_cfs_rq(m, cpu, cfs_rq);
5520 __init void init_sched_fair_class(void)
5523 open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
5526 nohz.next_balance = jiffies;
5527 zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
5528 cpu_notifier(sched_ilb_notifier, 0);