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>
30 #include <trace/events/sched.h>
35 * Targeted preemption latency for CPU-bound tasks:
36 * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
38 * NOTE: this latency value is not the same as the concept of
39 * 'timeslice length' - timeslices in CFS are of variable length
40 * and have no persistent notion like in traditional, time-slice
41 * based scheduling concepts.
43 * (to see the precise effective timeslice length of your workload,
44 * run vmstat and monitor the context-switches (cs) field)
46 unsigned int sysctl_sched_latency = 6000000ULL;
47 unsigned int normalized_sysctl_sched_latency = 6000000ULL;
50 * The initial- and re-scaling of tunables is configurable
51 * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
54 * SCHED_TUNABLESCALING_NONE - unscaled, always *1
55 * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
56 * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
58 enum sched_tunable_scaling sysctl_sched_tunable_scaling
59 = SCHED_TUNABLESCALING_LOG;
62 * Minimal preemption granularity for CPU-bound tasks:
63 * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
65 unsigned int sysctl_sched_min_granularity = 750000ULL;
66 unsigned int normalized_sysctl_sched_min_granularity = 750000ULL;
69 * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
71 static unsigned int sched_nr_latency = 8;
74 * After fork, child runs first. If set to 0 (default) then
75 * parent will (try to) run first.
77 unsigned int sysctl_sched_child_runs_first __read_mostly;
80 * SCHED_OTHER wake-up granularity.
81 * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
83 * This option delays the preemption effects of decoupled workloads
84 * and reduces their over-scheduling. Synchronous workloads will still
85 * have immediate wakeup/sleep latencies.
87 unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
88 unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
90 const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
93 * The exponential sliding window over which load is averaged for shares
97 unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
99 #ifdef CONFIG_CFS_BANDWIDTH
101 * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
102 * each time a cfs_rq requests quota.
104 * Note: in the case that the slice exceeds the runtime remaining (either due
105 * to consumption or the quota being specified to be smaller than the slice)
106 * we will always only issue the remaining available time.
108 * default: 5 msec, units: microseconds
110 unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL;
114 * Increase the granularity value when there are more CPUs,
115 * because with more CPUs the 'effective latency' as visible
116 * to users decreases. But the relationship is not linear,
117 * so pick a second-best guess by going with the log2 of the
120 * This idea comes from the SD scheduler of Con Kolivas:
122 static int get_update_sysctl_factor(void)
124 unsigned int cpus = min_t(int, num_online_cpus(), 8);
127 switch (sysctl_sched_tunable_scaling) {
128 case SCHED_TUNABLESCALING_NONE:
131 case SCHED_TUNABLESCALING_LINEAR:
134 case SCHED_TUNABLESCALING_LOG:
136 factor = 1 + ilog2(cpus);
143 static void update_sysctl(void)
145 unsigned int factor = get_update_sysctl_factor();
147 #define SET_SYSCTL(name) \
148 (sysctl_##name = (factor) * normalized_sysctl_##name)
149 SET_SYSCTL(sched_min_granularity);
150 SET_SYSCTL(sched_latency);
151 SET_SYSCTL(sched_wakeup_granularity);
155 void sched_init_granularity(void)
160 #if BITS_PER_LONG == 32
161 # define WMULT_CONST (~0UL)
163 # define WMULT_CONST (1UL << 32)
166 #define WMULT_SHIFT 32
169 * Shift right and round:
171 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
174 * delta *= weight / lw
177 calc_delta_mine(unsigned long delta_exec, unsigned long weight,
178 struct load_weight *lw)
183 * weight can be less than 2^SCHED_LOAD_RESOLUTION for task group sched
184 * entities since MIN_SHARES = 2. Treat weight as 1 if less than
185 * 2^SCHED_LOAD_RESOLUTION.
187 if (likely(weight > (1UL << SCHED_LOAD_RESOLUTION)))
188 tmp = (u64)delta_exec * scale_load_down(weight);
190 tmp = (u64)delta_exec;
192 if (!lw->inv_weight) {
193 unsigned long w = scale_load_down(lw->weight);
195 if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST))
197 else if (unlikely(!w))
198 lw->inv_weight = WMULT_CONST;
200 lw->inv_weight = WMULT_CONST / w;
204 * Check whether we'd overflow the 64-bit multiplication:
206 if (unlikely(tmp > WMULT_CONST))
207 tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight,
210 tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT);
212 return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
216 const struct sched_class fair_sched_class;
218 /**************************************************************
219 * CFS operations on generic schedulable entities:
222 #ifdef CONFIG_FAIR_GROUP_SCHED
224 /* cpu runqueue to which this cfs_rq is attached */
225 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
230 /* An entity is a task if it doesn't "own" a runqueue */
231 #define entity_is_task(se) (!se->my_q)
233 static inline struct task_struct *task_of(struct sched_entity *se)
235 #ifdef CONFIG_SCHED_DEBUG
236 WARN_ON_ONCE(!entity_is_task(se));
238 return container_of(se, struct task_struct, se);
241 /* Walk up scheduling entities hierarchy */
242 #define for_each_sched_entity(se) \
243 for (; se; se = se->parent)
245 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
250 /* runqueue on which this entity is (to be) queued */
251 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
256 /* runqueue "owned" by this group */
257 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
262 static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
264 if (!cfs_rq->on_list) {
266 * Ensure we either appear before our parent (if already
267 * enqueued) or force our parent to appear after us when it is
268 * enqueued. The fact that we always enqueue bottom-up
269 * reduces this to two cases.
271 if (cfs_rq->tg->parent &&
272 cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) {
273 list_add_rcu(&cfs_rq->leaf_cfs_rq_list,
274 &rq_of(cfs_rq)->leaf_cfs_rq_list);
276 list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
277 &rq_of(cfs_rq)->leaf_cfs_rq_list);
284 static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
286 if (cfs_rq->on_list) {
287 list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
292 /* Iterate thr' all leaf cfs_rq's on a runqueue */
293 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
294 list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
296 /* Do the two (enqueued) entities belong to the same group ? */
298 is_same_group(struct sched_entity *se, struct sched_entity *pse)
300 if (se->cfs_rq == pse->cfs_rq)
306 static inline struct sched_entity *parent_entity(struct sched_entity *se)
311 /* return depth at which a sched entity is present in the hierarchy */
312 static inline int depth_se(struct sched_entity *se)
316 for_each_sched_entity(se)
323 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
325 int se_depth, pse_depth;
328 * preemption test can be made between sibling entities who are in the
329 * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
330 * both tasks until we find their ancestors who are siblings of common
334 /* First walk up until both entities are at same depth */
335 se_depth = depth_se(*se);
336 pse_depth = depth_se(*pse);
338 while (se_depth > pse_depth) {
340 *se = parent_entity(*se);
343 while (pse_depth > se_depth) {
345 *pse = parent_entity(*pse);
348 while (!is_same_group(*se, *pse)) {
349 *se = parent_entity(*se);
350 *pse = parent_entity(*pse);
354 #else /* !CONFIG_FAIR_GROUP_SCHED */
356 static inline struct task_struct *task_of(struct sched_entity *se)
358 return container_of(se, struct task_struct, se);
361 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
363 return container_of(cfs_rq, struct rq, cfs);
366 #define entity_is_task(se) 1
368 #define for_each_sched_entity(se) \
369 for (; se; se = NULL)
371 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
373 return &task_rq(p)->cfs;
376 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
378 struct task_struct *p = task_of(se);
379 struct rq *rq = task_rq(p);
384 /* runqueue "owned" by this group */
385 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
390 static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
394 static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
398 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
399 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
402 is_same_group(struct sched_entity *se, struct sched_entity *pse)
407 static inline struct sched_entity *parent_entity(struct sched_entity *se)
413 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
417 #endif /* CONFIG_FAIR_GROUP_SCHED */
419 static __always_inline
420 void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec);
422 /**************************************************************
423 * Scheduling class tree data structure manipulation methods:
426 static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime)
428 s64 delta = (s64)(vruntime - min_vruntime);
430 min_vruntime = vruntime;
435 static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
437 s64 delta = (s64)(vruntime - min_vruntime);
439 min_vruntime = vruntime;
444 static inline int entity_before(struct sched_entity *a,
445 struct sched_entity *b)
447 return (s64)(a->vruntime - b->vruntime) < 0;
450 static void update_min_vruntime(struct cfs_rq *cfs_rq)
452 u64 vruntime = cfs_rq->min_vruntime;
455 vruntime = cfs_rq->curr->vruntime;
457 if (cfs_rq->rb_leftmost) {
458 struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost,
463 vruntime = se->vruntime;
465 vruntime = min_vruntime(vruntime, se->vruntime);
468 cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
471 cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
476 * Enqueue an entity into the rb-tree:
478 static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
480 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
481 struct rb_node *parent = NULL;
482 struct sched_entity *entry;
486 * Find the right place in the rbtree:
490 entry = rb_entry(parent, struct sched_entity, run_node);
492 * We dont care about collisions. Nodes with
493 * the same key stay together.
495 if (entity_before(se, entry)) {
496 link = &parent->rb_left;
498 link = &parent->rb_right;
504 * Maintain a cache of leftmost tree entries (it is frequently
508 cfs_rq->rb_leftmost = &se->run_node;
510 rb_link_node(&se->run_node, parent, link);
511 rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
514 static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
516 if (cfs_rq->rb_leftmost == &se->run_node) {
517 struct rb_node *next_node;
519 next_node = rb_next(&se->run_node);
520 cfs_rq->rb_leftmost = next_node;
523 rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
526 struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
528 struct rb_node *left = cfs_rq->rb_leftmost;
533 return rb_entry(left, struct sched_entity, run_node);
536 static struct sched_entity *__pick_next_entity(struct sched_entity *se)
538 struct rb_node *next = rb_next(&se->run_node);
543 return rb_entry(next, struct sched_entity, run_node);
546 #ifdef CONFIG_SCHED_DEBUG
547 struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
549 struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
554 return rb_entry(last, struct sched_entity, run_node);
557 /**************************************************************
558 * Scheduling class statistics methods:
561 int sched_proc_update_handler(struct ctl_table *table, int write,
562 void __user *buffer, size_t *lenp,
565 int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
566 int factor = get_update_sysctl_factor();
571 sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
572 sysctl_sched_min_granularity);
574 #define WRT_SYSCTL(name) \
575 (normalized_sysctl_##name = sysctl_##name / (factor))
576 WRT_SYSCTL(sched_min_granularity);
577 WRT_SYSCTL(sched_latency);
578 WRT_SYSCTL(sched_wakeup_granularity);
588 static inline unsigned long
589 calc_delta_fair(unsigned long delta, struct sched_entity *se)
591 if (unlikely(se->load.weight != NICE_0_LOAD))
592 delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load);
598 * The idea is to set a period in which each task runs once.
600 * When there are too many tasks (sched_nr_latency) we have to stretch
601 * this period because otherwise the slices get too small.
603 * p = (nr <= nl) ? l : l*nr/nl
605 static u64 __sched_period(unsigned long nr_running)
607 u64 period = sysctl_sched_latency;
608 unsigned long nr_latency = sched_nr_latency;
610 if (unlikely(nr_running > nr_latency)) {
611 period = sysctl_sched_min_granularity;
612 period *= nr_running;
619 * We calculate the wall-time slice from the period by taking a part
620 * proportional to the weight.
624 static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
626 u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq);
628 for_each_sched_entity(se) {
629 struct load_weight *load;
630 struct load_weight lw;
632 cfs_rq = cfs_rq_of(se);
633 load = &cfs_rq->load;
635 if (unlikely(!se->on_rq)) {
638 update_load_add(&lw, se->load.weight);
641 slice = calc_delta_mine(slice, se->load.weight, load);
647 * We calculate the vruntime slice of a to be inserted task
651 static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
653 return calc_delta_fair(sched_slice(cfs_rq, se), se);
656 static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update);
657 static void update_cfs_shares(struct cfs_rq *cfs_rq);
660 * Update the current task's runtime statistics. Skip current tasks that
661 * are not in our scheduling class.
664 __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
665 unsigned long delta_exec)
667 unsigned long delta_exec_weighted;
669 schedstat_set(curr->statistics.exec_max,
670 max((u64)delta_exec, curr->statistics.exec_max));
672 curr->sum_exec_runtime += delta_exec;
673 schedstat_add(cfs_rq, exec_clock, delta_exec);
674 delta_exec_weighted = calc_delta_fair(delta_exec, curr);
676 curr->vruntime += delta_exec_weighted;
677 update_min_vruntime(cfs_rq);
679 #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
680 cfs_rq->load_unacc_exec_time += delta_exec;
684 static void update_curr(struct cfs_rq *cfs_rq)
686 struct sched_entity *curr = cfs_rq->curr;
687 u64 now = rq_of(cfs_rq)->clock_task;
688 unsigned long delta_exec;
694 * Get the amount of time the current task was running
695 * since the last time we changed load (this cannot
696 * overflow on 32 bits):
698 delta_exec = (unsigned long)(now - curr->exec_start);
702 __update_curr(cfs_rq, curr, delta_exec);
703 curr->exec_start = now;
705 if (entity_is_task(curr)) {
706 struct task_struct *curtask = task_of(curr);
708 trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
709 cpuacct_charge(curtask, delta_exec);
710 account_group_exec_runtime(curtask, delta_exec);
713 account_cfs_rq_runtime(cfs_rq, delta_exec);
717 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
719 schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock);
723 * Task is being enqueued - update stats:
725 static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
728 * Are we enqueueing a waiting task? (for current tasks
729 * a dequeue/enqueue event is a NOP)
731 if (se != cfs_rq->curr)
732 update_stats_wait_start(cfs_rq, se);
736 update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
738 schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max,
739 rq_of(cfs_rq)->clock - se->statistics.wait_start));
740 schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1);
741 schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum +
742 rq_of(cfs_rq)->clock - se->statistics.wait_start);
743 #ifdef CONFIG_SCHEDSTATS
744 if (entity_is_task(se)) {
745 trace_sched_stat_wait(task_of(se),
746 rq_of(cfs_rq)->clock - se->statistics.wait_start);
749 schedstat_set(se->statistics.wait_start, 0);
753 update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
756 * Mark the end of the wait period if dequeueing a
759 if (se != cfs_rq->curr)
760 update_stats_wait_end(cfs_rq, se);
764 * We are picking a new current task - update its stats:
767 update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
770 * We are starting a new run period:
772 se->exec_start = rq_of(cfs_rq)->clock_task;
775 /**************************************************
776 * Scheduling class queueing methods:
780 account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
782 update_load_add(&cfs_rq->load, se->load.weight);
783 if (!parent_entity(se))
784 update_load_add(&rq_of(cfs_rq)->load, se->load.weight);
786 if (entity_is_task(se))
787 list_add(&se->group_node, &rq_of(cfs_rq)->cfs_tasks);
789 cfs_rq->nr_running++;
793 account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
795 update_load_sub(&cfs_rq->load, se->load.weight);
796 if (!parent_entity(se))
797 update_load_sub(&rq_of(cfs_rq)->load, se->load.weight);
798 if (entity_is_task(se))
799 list_del_init(&se->group_node);
800 cfs_rq->nr_running--;
803 #ifdef CONFIG_FAIR_GROUP_SCHED
804 /* we need this in update_cfs_load and load-balance functions below */
805 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
807 static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq,
810 struct task_group *tg = cfs_rq->tg;
813 load_avg = div64_u64(cfs_rq->load_avg, cfs_rq->load_period+1);
814 load_avg -= cfs_rq->load_contribution;
816 if (global_update || abs(load_avg) > cfs_rq->load_contribution / 8) {
817 atomic_add(load_avg, &tg->load_weight);
818 cfs_rq->load_contribution += load_avg;
822 static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
824 u64 period = sysctl_sched_shares_window;
826 unsigned long load = cfs_rq->load.weight;
828 if (cfs_rq->tg == &root_task_group || throttled_hierarchy(cfs_rq))
831 now = rq_of(cfs_rq)->clock_task;
832 delta = now - cfs_rq->load_stamp;
834 /* truncate load history at 4 idle periods */
835 if (cfs_rq->load_stamp > cfs_rq->load_last &&
836 now - cfs_rq->load_last > 4 * period) {
837 cfs_rq->load_period = 0;
838 cfs_rq->load_avg = 0;
842 cfs_rq->load_stamp = now;
843 cfs_rq->load_unacc_exec_time = 0;
844 cfs_rq->load_period += delta;
846 cfs_rq->load_last = now;
847 cfs_rq->load_avg += delta * load;
850 /* consider updating load contribution on each fold or truncate */
851 if (global_update || cfs_rq->load_period > period
852 || !cfs_rq->load_period)
853 update_cfs_rq_load_contribution(cfs_rq, global_update);
855 while (cfs_rq->load_period > period) {
857 * Inline assembly required to prevent the compiler
858 * optimising this loop into a divmod call.
859 * See __iter_div_u64_rem() for another example of this.
861 asm("" : "+rm" (cfs_rq->load_period));
862 cfs_rq->load_period /= 2;
863 cfs_rq->load_avg /= 2;
866 if (!cfs_rq->curr && !cfs_rq->nr_running && !cfs_rq->load_avg)
867 list_del_leaf_cfs_rq(cfs_rq);
870 static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq)
875 * Use this CPU's actual weight instead of the last load_contribution
876 * to gain a more accurate current total weight. See
877 * update_cfs_rq_load_contribution().
879 tg_weight = atomic_read(&tg->load_weight);
880 tg_weight -= cfs_rq->load_contribution;
881 tg_weight += cfs_rq->load.weight;
886 static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
888 long tg_weight, load, shares;
890 tg_weight = calc_tg_weight(tg, cfs_rq);
891 load = cfs_rq->load.weight;
893 shares = (tg->shares * load);
897 if (shares < MIN_SHARES)
899 if (shares > tg->shares)
905 static void update_entity_shares_tick(struct cfs_rq *cfs_rq)
907 if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
908 update_cfs_load(cfs_rq, 0);
909 update_cfs_shares(cfs_rq);
912 # else /* CONFIG_SMP */
913 static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
917 static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
922 static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
925 # endif /* CONFIG_SMP */
926 static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
927 unsigned long weight)
930 /* commit outstanding execution time */
931 if (cfs_rq->curr == se)
933 account_entity_dequeue(cfs_rq, se);
936 update_load_set(&se->load, weight);
939 account_entity_enqueue(cfs_rq, se);
942 static void update_cfs_shares(struct cfs_rq *cfs_rq)
944 struct task_group *tg;
945 struct sched_entity *se;
949 se = tg->se[cpu_of(rq_of(cfs_rq))];
950 if (!se || throttled_hierarchy(cfs_rq))
953 if (likely(se->load.weight == tg->shares))
956 shares = calc_cfs_shares(cfs_rq, tg);
958 reweight_entity(cfs_rq_of(se), se, shares);
960 #else /* CONFIG_FAIR_GROUP_SCHED */
961 static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
965 static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
969 static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
972 #endif /* CONFIG_FAIR_GROUP_SCHED */
977 * val * y^n, where y^32 ~= 0.5 (~1 scheduling period)
979 static __always_inline u64 decay_load(u64 val, u64 n)
981 for (; n && val; n--) {
990 * We can represent the historical contribution to runnable average as the
991 * coefficients of a geometric series. To do this we sub-divide our runnable
992 * history into segments of approximately 1ms (1024us); label the segment that
993 * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g.
995 * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ...
997 * (now) (~1ms ago) (~2ms ago)
999 * Let u_i denote the fraction of p_i that the entity was runnable.
1001 * We then designate the fractions u_i as our co-efficients, yielding the
1002 * following representation of historical load:
1003 * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ...
1005 * We choose y based on the with of a reasonably scheduling period, fixing:
1008 * This means that the contribution to load ~32ms ago (u_32) will be weighted
1009 * approximately half as much as the contribution to load within the last ms
1012 * When a period "rolls over" and we have new u_0`, multiplying the previous
1013 * sum again by y is sufficient to update:
1014 * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... )
1015 * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
1017 static __always_inline int __update_entity_runnable_avg(u64 now,
1018 struct sched_avg *sa,
1022 int delta_w, decayed = 0;
1024 delta = now - sa->last_runnable_update;
1026 * This should only happen when time goes backwards, which it
1027 * unfortunately does during sched clock init when we swap over to TSC.
1029 if ((s64)delta < 0) {
1030 sa->last_runnable_update = now;
1035 * Use 1024ns as the unit of measurement since it's a reasonable
1036 * approximation of 1us and fast to compute.
1041 sa->last_runnable_update = now;
1043 /* delta_w is the amount already accumulated against our next period */
1044 delta_w = sa->runnable_avg_period % 1024;
1045 if (delta + delta_w >= 1024) {
1046 /* period roll-over */
1050 * Now that we know we're crossing a period boundary, figure
1051 * out how much from delta we need to complete the current
1052 * period and accrue it.
1054 delta_w = 1024 - delta_w;
1055 BUG_ON(delta_w > delta);
1058 sa->runnable_avg_sum += delta_w;
1059 sa->runnable_avg_period += delta_w;
1062 * Remainder of delta initiates a new period, roll over
1065 sa->runnable_avg_sum =
1066 decay_load(sa->runnable_avg_sum, 1);
1067 sa->runnable_avg_period =
1068 decay_load(sa->runnable_avg_period, 1);
1071 /* New period is empty */
1073 } while (delta >= 1024);
1076 /* Remainder of delta accrued against u_0` */
1078 sa->runnable_avg_sum += delta;
1079 sa->runnable_avg_period += delta;
1084 /* Update a sched_entity's runnable average */
1085 static inline void update_entity_load_avg(struct sched_entity *se)
1087 __update_entity_runnable_avg(rq_of(cfs_rq_of(se))->clock_task, &se->avg,
1091 static inline void update_entity_load_avg(struct sched_entity *se) {}
1094 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
1096 #ifdef CONFIG_SCHEDSTATS
1097 struct task_struct *tsk = NULL;
1099 if (entity_is_task(se))
1102 if (se->statistics.sleep_start) {
1103 u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start;
1108 if (unlikely(delta > se->statistics.sleep_max))
1109 se->statistics.sleep_max = delta;
1111 se->statistics.sleep_start = 0;
1112 se->statistics.sum_sleep_runtime += delta;
1115 account_scheduler_latency(tsk, delta >> 10, 1);
1116 trace_sched_stat_sleep(tsk, delta);
1119 if (se->statistics.block_start) {
1120 u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start;
1125 if (unlikely(delta > se->statistics.block_max))
1126 se->statistics.block_max = delta;
1128 se->statistics.block_start = 0;
1129 se->statistics.sum_sleep_runtime += delta;
1132 if (tsk->in_iowait) {
1133 se->statistics.iowait_sum += delta;
1134 se->statistics.iowait_count++;
1135 trace_sched_stat_iowait(tsk, delta);
1138 trace_sched_stat_blocked(tsk, delta);
1141 * Blocking time is in units of nanosecs, so shift by
1142 * 20 to get a milliseconds-range estimation of the
1143 * amount of time that the task spent sleeping:
1145 if (unlikely(prof_on == SLEEP_PROFILING)) {
1146 profile_hits(SLEEP_PROFILING,
1147 (void *)get_wchan(tsk),
1150 account_scheduler_latency(tsk, delta >> 10, 0);
1156 static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
1158 #ifdef CONFIG_SCHED_DEBUG
1159 s64 d = se->vruntime - cfs_rq->min_vruntime;
1164 if (d > 3*sysctl_sched_latency)
1165 schedstat_inc(cfs_rq, nr_spread_over);
1170 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
1172 u64 vruntime = cfs_rq->min_vruntime;
1175 * The 'current' period is already promised to the current tasks,
1176 * however the extra weight of the new task will slow them down a
1177 * little, place the new task so that it fits in the slot that
1178 * stays open at the end.
1180 if (initial && sched_feat(START_DEBIT))
1181 vruntime += sched_vslice(cfs_rq, se);
1183 /* sleeps up to a single latency don't count. */
1185 unsigned long thresh = sysctl_sched_latency;
1188 * Halve their sleep time's effect, to allow
1189 * for a gentler effect of sleepers:
1191 if (sched_feat(GENTLE_FAIR_SLEEPERS))
1197 /* ensure we never gain time by being placed backwards. */
1198 vruntime = max_vruntime(se->vruntime, vruntime);
1200 se->vruntime = vruntime;
1203 static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
1206 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1209 * Update the normalized vruntime before updating min_vruntime
1210 * through callig update_curr().
1212 if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING))
1213 se->vruntime += cfs_rq->min_vruntime;
1216 * Update run-time statistics of the 'current'.
1218 update_curr(cfs_rq);
1219 update_cfs_load(cfs_rq, 0);
1220 update_entity_load_avg(se);
1221 account_entity_enqueue(cfs_rq, se);
1222 update_cfs_shares(cfs_rq);
1224 if (flags & ENQUEUE_WAKEUP) {
1225 place_entity(cfs_rq, se, 0);
1226 enqueue_sleeper(cfs_rq, se);
1229 update_stats_enqueue(cfs_rq, se);
1230 check_spread(cfs_rq, se);
1231 if (se != cfs_rq->curr)
1232 __enqueue_entity(cfs_rq, se);
1235 if (cfs_rq->nr_running == 1) {
1236 list_add_leaf_cfs_rq(cfs_rq);
1237 check_enqueue_throttle(cfs_rq);
1241 static void __clear_buddies_last(struct sched_entity *se)
1243 for_each_sched_entity(se) {
1244 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1245 if (cfs_rq->last == se)
1246 cfs_rq->last = NULL;
1252 static void __clear_buddies_next(struct sched_entity *se)
1254 for_each_sched_entity(se) {
1255 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1256 if (cfs_rq->next == se)
1257 cfs_rq->next = NULL;
1263 static void __clear_buddies_skip(struct sched_entity *se)
1265 for_each_sched_entity(se) {
1266 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1267 if (cfs_rq->skip == se)
1268 cfs_rq->skip = NULL;
1274 static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
1276 if (cfs_rq->last == se)
1277 __clear_buddies_last(se);
1279 if (cfs_rq->next == se)
1280 __clear_buddies_next(se);
1282 if (cfs_rq->skip == se)
1283 __clear_buddies_skip(se);
1286 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
1289 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1292 * Update run-time statistics of the 'current'.
1294 update_curr(cfs_rq);
1295 update_entity_load_avg(se);
1297 update_stats_dequeue(cfs_rq, se);
1298 if (flags & DEQUEUE_SLEEP) {
1299 #ifdef CONFIG_SCHEDSTATS
1300 if (entity_is_task(se)) {
1301 struct task_struct *tsk = task_of(se);
1303 if (tsk->state & TASK_INTERRUPTIBLE)
1304 se->statistics.sleep_start = rq_of(cfs_rq)->clock;
1305 if (tsk->state & TASK_UNINTERRUPTIBLE)
1306 se->statistics.block_start = rq_of(cfs_rq)->clock;
1311 clear_buddies(cfs_rq, se);
1313 if (se != cfs_rq->curr)
1314 __dequeue_entity(cfs_rq, se);
1316 update_cfs_load(cfs_rq, 0);
1317 account_entity_dequeue(cfs_rq, se);
1320 * Normalize the entity after updating the min_vruntime because the
1321 * update can refer to the ->curr item and we need to reflect this
1322 * movement in our normalized position.
1324 if (!(flags & DEQUEUE_SLEEP))
1325 se->vruntime -= cfs_rq->min_vruntime;
1327 /* return excess runtime on last dequeue */
1328 return_cfs_rq_runtime(cfs_rq);
1330 update_min_vruntime(cfs_rq);
1331 update_cfs_shares(cfs_rq);
1335 * Preempt the current task with a newly woken task if needed:
1338 check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
1340 unsigned long ideal_runtime, delta_exec;
1341 struct sched_entity *se;
1344 ideal_runtime = sched_slice(cfs_rq, curr);
1345 delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
1346 if (delta_exec > ideal_runtime) {
1347 resched_task(rq_of(cfs_rq)->curr);
1349 * The current task ran long enough, ensure it doesn't get
1350 * re-elected due to buddy favours.
1352 clear_buddies(cfs_rq, curr);
1357 * Ensure that a task that missed wakeup preemption by a
1358 * narrow margin doesn't have to wait for a full slice.
1359 * This also mitigates buddy induced latencies under load.
1361 if (delta_exec < sysctl_sched_min_granularity)
1364 se = __pick_first_entity(cfs_rq);
1365 delta = curr->vruntime - se->vruntime;
1370 if (delta > ideal_runtime)
1371 resched_task(rq_of(cfs_rq)->curr);
1375 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
1377 /* 'current' is not kept within the tree. */
1380 * Any task has to be enqueued before it get to execute on
1381 * a CPU. So account for the time it spent waiting on the
1384 update_stats_wait_end(cfs_rq, se);
1385 __dequeue_entity(cfs_rq, se);
1388 update_stats_curr_start(cfs_rq, se);
1390 #ifdef CONFIG_SCHEDSTATS
1392 * Track our maximum slice length, if the CPU's load is at
1393 * least twice that of our own weight (i.e. dont track it
1394 * when there are only lesser-weight tasks around):
1396 if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
1397 se->statistics.slice_max = max(se->statistics.slice_max,
1398 se->sum_exec_runtime - se->prev_sum_exec_runtime);
1401 se->prev_sum_exec_runtime = se->sum_exec_runtime;
1405 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
1408 * Pick the next process, keeping these things in mind, in this order:
1409 * 1) keep things fair between processes/task groups
1410 * 2) pick the "next" process, since someone really wants that to run
1411 * 3) pick the "last" process, for cache locality
1412 * 4) do not run the "skip" process, if something else is available
1414 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
1416 struct sched_entity *se = __pick_first_entity(cfs_rq);
1417 struct sched_entity *left = se;
1420 * Avoid running the skip buddy, if running something else can
1421 * be done without getting too unfair.
1423 if (cfs_rq->skip == se) {
1424 struct sched_entity *second = __pick_next_entity(se);
1425 if (second && wakeup_preempt_entity(second, left) < 1)
1430 * Prefer last buddy, try to return the CPU to a preempted task.
1432 if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
1436 * Someone really wants this to run. If it's not unfair, run it.
1438 if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
1441 clear_buddies(cfs_rq, se);
1446 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
1448 static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
1451 * If still on the runqueue then deactivate_task()
1452 * was not called and update_curr() has to be done:
1455 update_curr(cfs_rq);
1457 /* throttle cfs_rqs exceeding runtime */
1458 check_cfs_rq_runtime(cfs_rq);
1460 check_spread(cfs_rq, prev);
1462 update_stats_wait_start(cfs_rq, prev);
1463 /* Put 'current' back into the tree. */
1464 __enqueue_entity(cfs_rq, prev);
1465 /* in !on_rq case, update occurred at dequeue */
1466 update_entity_load_avg(prev);
1468 cfs_rq->curr = NULL;
1472 entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
1475 * Update run-time statistics of the 'current'.
1477 update_curr(cfs_rq);
1480 * Ensure that runnable average is periodically updated.
1482 update_entity_load_avg(curr);
1485 * Update share accounting for long-running entities.
1487 update_entity_shares_tick(cfs_rq);
1489 #ifdef CONFIG_SCHED_HRTICK
1491 * queued ticks are scheduled to match the slice, so don't bother
1492 * validating it and just reschedule.
1495 resched_task(rq_of(cfs_rq)->curr);
1499 * don't let the period tick interfere with the hrtick preemption
1501 if (!sched_feat(DOUBLE_TICK) &&
1502 hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
1506 if (cfs_rq->nr_running > 1)
1507 check_preempt_tick(cfs_rq, curr);
1511 /**************************************************
1512 * CFS bandwidth control machinery
1515 #ifdef CONFIG_CFS_BANDWIDTH
1517 #ifdef HAVE_JUMP_LABEL
1518 static struct static_key __cfs_bandwidth_used;
1520 static inline bool cfs_bandwidth_used(void)
1522 return static_key_false(&__cfs_bandwidth_used);
1525 void account_cfs_bandwidth_used(int enabled, int was_enabled)
1527 /* only need to count groups transitioning between enabled/!enabled */
1528 if (enabled && !was_enabled)
1529 static_key_slow_inc(&__cfs_bandwidth_used);
1530 else if (!enabled && was_enabled)
1531 static_key_slow_dec(&__cfs_bandwidth_used);
1533 #else /* HAVE_JUMP_LABEL */
1534 static bool cfs_bandwidth_used(void)
1539 void account_cfs_bandwidth_used(int enabled, int was_enabled) {}
1540 #endif /* HAVE_JUMP_LABEL */
1543 * default period for cfs group bandwidth.
1544 * default: 0.1s, units: nanoseconds
1546 static inline u64 default_cfs_period(void)
1548 return 100000000ULL;
1551 static inline u64 sched_cfs_bandwidth_slice(void)
1553 return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
1557 * Replenish runtime according to assigned quota and update expiration time.
1558 * We use sched_clock_cpu directly instead of rq->clock to avoid adding
1559 * additional synchronization around rq->lock.
1561 * requires cfs_b->lock
1563 void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
1567 if (cfs_b->quota == RUNTIME_INF)
1570 now = sched_clock_cpu(smp_processor_id());
1571 cfs_b->runtime = cfs_b->quota;
1572 cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period);
1575 static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
1577 return &tg->cfs_bandwidth;
1580 /* returns 0 on failure to allocate runtime */
1581 static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
1583 struct task_group *tg = cfs_rq->tg;
1584 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
1585 u64 amount = 0, min_amount, expires;
1587 /* note: this is a positive sum as runtime_remaining <= 0 */
1588 min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining;
1590 raw_spin_lock(&cfs_b->lock);
1591 if (cfs_b->quota == RUNTIME_INF)
1592 amount = min_amount;
1595 * If the bandwidth pool has become inactive, then at least one
1596 * period must have elapsed since the last consumption.
1597 * Refresh the global state and ensure bandwidth timer becomes
1600 if (!cfs_b->timer_active) {
1601 __refill_cfs_bandwidth_runtime(cfs_b);
1602 __start_cfs_bandwidth(cfs_b);
1605 if (cfs_b->runtime > 0) {
1606 amount = min(cfs_b->runtime, min_amount);
1607 cfs_b->runtime -= amount;
1611 expires = cfs_b->runtime_expires;
1612 raw_spin_unlock(&cfs_b->lock);
1614 cfs_rq->runtime_remaining += amount;
1616 * we may have advanced our local expiration to account for allowed
1617 * spread between our sched_clock and the one on which runtime was
1620 if ((s64)(expires - cfs_rq->runtime_expires) > 0)
1621 cfs_rq->runtime_expires = expires;
1623 return cfs_rq->runtime_remaining > 0;
1627 * Note: This depends on the synchronization provided by sched_clock and the
1628 * fact that rq->clock snapshots this value.
1630 static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq)
1632 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
1633 struct rq *rq = rq_of(cfs_rq);
1635 /* if the deadline is ahead of our clock, nothing to do */
1636 if (likely((s64)(rq->clock - cfs_rq->runtime_expires) < 0))
1639 if (cfs_rq->runtime_remaining < 0)
1643 * If the local deadline has passed we have to consider the
1644 * possibility that our sched_clock is 'fast' and the global deadline
1645 * has not truly expired.
1647 * Fortunately we can check determine whether this the case by checking
1648 * whether the global deadline has advanced.
1651 if ((s64)(cfs_rq->runtime_expires - cfs_b->runtime_expires) >= 0) {
1652 /* extend local deadline, drift is bounded above by 2 ticks */
1653 cfs_rq->runtime_expires += TICK_NSEC;
1655 /* global deadline is ahead, expiration has passed */
1656 cfs_rq->runtime_remaining = 0;
1660 static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
1661 unsigned long delta_exec)
1663 /* dock delta_exec before expiring quota (as it could span periods) */
1664 cfs_rq->runtime_remaining -= delta_exec;
1665 expire_cfs_rq_runtime(cfs_rq);
1667 if (likely(cfs_rq->runtime_remaining > 0))
1671 * if we're unable to extend our runtime we resched so that the active
1672 * hierarchy can be throttled
1674 if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
1675 resched_task(rq_of(cfs_rq)->curr);
1678 static __always_inline
1679 void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec)
1681 if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
1684 __account_cfs_rq_runtime(cfs_rq, delta_exec);
1687 static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
1689 return cfs_bandwidth_used() && cfs_rq->throttled;
1692 /* check whether cfs_rq, or any parent, is throttled */
1693 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
1695 return cfs_bandwidth_used() && cfs_rq->throttle_count;
1699 * Ensure that neither of the group entities corresponding to src_cpu or
1700 * dest_cpu are members of a throttled hierarchy when performing group
1701 * load-balance operations.
1703 static inline int throttled_lb_pair(struct task_group *tg,
1704 int src_cpu, int dest_cpu)
1706 struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
1708 src_cfs_rq = tg->cfs_rq[src_cpu];
1709 dest_cfs_rq = tg->cfs_rq[dest_cpu];
1711 return throttled_hierarchy(src_cfs_rq) ||
1712 throttled_hierarchy(dest_cfs_rq);
1715 /* updated child weight may affect parent so we have to do this bottom up */
1716 static int tg_unthrottle_up(struct task_group *tg, void *data)
1718 struct rq *rq = data;
1719 struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
1721 cfs_rq->throttle_count--;
1723 if (!cfs_rq->throttle_count) {
1724 u64 delta = rq->clock_task - cfs_rq->load_stamp;
1726 /* leaving throttled state, advance shares averaging windows */
1727 cfs_rq->load_stamp += delta;
1728 cfs_rq->load_last += delta;
1730 /* update entity weight now that we are on_rq again */
1731 update_cfs_shares(cfs_rq);
1738 static int tg_throttle_down(struct task_group *tg, void *data)
1740 struct rq *rq = data;
1741 struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
1743 /* group is entering throttled state, record last load */
1744 if (!cfs_rq->throttle_count)
1745 update_cfs_load(cfs_rq, 0);
1746 cfs_rq->throttle_count++;
1751 static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
1753 struct rq *rq = rq_of(cfs_rq);
1754 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
1755 struct sched_entity *se;
1756 long task_delta, dequeue = 1;
1758 se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
1760 /* account load preceding throttle */
1762 walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
1765 task_delta = cfs_rq->h_nr_running;
1766 for_each_sched_entity(se) {
1767 struct cfs_rq *qcfs_rq = cfs_rq_of(se);
1768 /* throttled entity or throttle-on-deactivate */
1773 dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
1774 qcfs_rq->h_nr_running -= task_delta;
1776 if (qcfs_rq->load.weight)
1781 rq->nr_running -= task_delta;
1783 cfs_rq->throttled = 1;
1784 cfs_rq->throttled_timestamp = rq->clock;
1785 raw_spin_lock(&cfs_b->lock);
1786 list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
1787 raw_spin_unlock(&cfs_b->lock);
1790 void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
1792 struct rq *rq = rq_of(cfs_rq);
1793 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
1794 struct sched_entity *se;
1798 se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
1800 cfs_rq->throttled = 0;
1801 raw_spin_lock(&cfs_b->lock);
1802 cfs_b->throttled_time += rq->clock - cfs_rq->throttled_timestamp;
1803 list_del_rcu(&cfs_rq->throttled_list);
1804 raw_spin_unlock(&cfs_b->lock);
1805 cfs_rq->throttled_timestamp = 0;
1807 update_rq_clock(rq);
1808 /* update hierarchical throttle state */
1809 walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
1811 if (!cfs_rq->load.weight)
1814 task_delta = cfs_rq->h_nr_running;
1815 for_each_sched_entity(se) {
1819 cfs_rq = cfs_rq_of(se);
1821 enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);
1822 cfs_rq->h_nr_running += task_delta;
1824 if (cfs_rq_throttled(cfs_rq))
1829 rq->nr_running += task_delta;
1831 /* determine whether we need to wake up potentially idle cpu */
1832 if (rq->curr == rq->idle && rq->cfs.nr_running)
1833 resched_task(rq->curr);
1836 static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
1837 u64 remaining, u64 expires)
1839 struct cfs_rq *cfs_rq;
1840 u64 runtime = remaining;
1843 list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
1845 struct rq *rq = rq_of(cfs_rq);
1847 raw_spin_lock(&rq->lock);
1848 if (!cfs_rq_throttled(cfs_rq))
1851 runtime = -cfs_rq->runtime_remaining + 1;
1852 if (runtime > remaining)
1853 runtime = remaining;
1854 remaining -= runtime;
1856 cfs_rq->runtime_remaining += runtime;
1857 cfs_rq->runtime_expires = expires;
1859 /* we check whether we're throttled above */
1860 if (cfs_rq->runtime_remaining > 0)
1861 unthrottle_cfs_rq(cfs_rq);
1864 raw_spin_unlock(&rq->lock);
1875 * Responsible for refilling a task_group's bandwidth and unthrottling its
1876 * cfs_rqs as appropriate. If there has been no activity within the last
1877 * period the timer is deactivated until scheduling resumes; cfs_b->idle is
1878 * used to track this state.
1880 static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
1882 u64 runtime, runtime_expires;
1883 int idle = 1, throttled;
1885 raw_spin_lock(&cfs_b->lock);
1886 /* no need to continue the timer with no bandwidth constraint */
1887 if (cfs_b->quota == RUNTIME_INF)
1890 throttled = !list_empty(&cfs_b->throttled_cfs_rq);
1891 /* idle depends on !throttled (for the case of a large deficit) */
1892 idle = cfs_b->idle && !throttled;
1893 cfs_b->nr_periods += overrun;
1895 /* if we're going inactive then everything else can be deferred */
1899 __refill_cfs_bandwidth_runtime(cfs_b);
1902 /* mark as potentially idle for the upcoming period */
1907 /* account preceding periods in which throttling occurred */
1908 cfs_b->nr_throttled += overrun;
1911 * There are throttled entities so we must first use the new bandwidth
1912 * to unthrottle them before making it generally available. This
1913 * ensures that all existing debts will be paid before a new cfs_rq is
1916 runtime = cfs_b->runtime;
1917 runtime_expires = cfs_b->runtime_expires;
1921 * This check is repeated as we are holding onto the new bandwidth
1922 * while we unthrottle. This can potentially race with an unthrottled
1923 * group trying to acquire new bandwidth from the global pool.
1925 while (throttled && runtime > 0) {
1926 raw_spin_unlock(&cfs_b->lock);
1927 /* we can't nest cfs_b->lock while distributing bandwidth */
1928 runtime = distribute_cfs_runtime(cfs_b, runtime,
1930 raw_spin_lock(&cfs_b->lock);
1932 throttled = !list_empty(&cfs_b->throttled_cfs_rq);
1935 /* return (any) remaining runtime */
1936 cfs_b->runtime = runtime;
1938 * While we are ensured activity in the period following an
1939 * unthrottle, this also covers the case in which the new bandwidth is
1940 * insufficient to cover the existing bandwidth deficit. (Forcing the
1941 * timer to remain active while there are any throttled entities.)
1946 cfs_b->timer_active = 0;
1947 raw_spin_unlock(&cfs_b->lock);
1952 /* a cfs_rq won't donate quota below this amount */
1953 static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
1954 /* minimum remaining period time to redistribute slack quota */
1955 static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
1956 /* how long we wait to gather additional slack before distributing */
1957 static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
1959 /* are we near the end of the current quota period? */
1960 static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
1962 struct hrtimer *refresh_timer = &cfs_b->period_timer;
1965 /* if the call-back is running a quota refresh is already occurring */
1966 if (hrtimer_callback_running(refresh_timer))
1969 /* is a quota refresh about to occur? */
1970 remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
1971 if (remaining < min_expire)
1977 static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
1979 u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
1981 /* if there's a quota refresh soon don't bother with slack */
1982 if (runtime_refresh_within(cfs_b, min_left))
1985 start_bandwidth_timer(&cfs_b->slack_timer,
1986 ns_to_ktime(cfs_bandwidth_slack_period));
1989 /* we know any runtime found here is valid as update_curr() precedes return */
1990 static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
1992 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
1993 s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
1995 if (slack_runtime <= 0)
1998 raw_spin_lock(&cfs_b->lock);
1999 if (cfs_b->quota != RUNTIME_INF &&
2000 cfs_rq->runtime_expires == cfs_b->runtime_expires) {
2001 cfs_b->runtime += slack_runtime;
2003 /* we are under rq->lock, defer unthrottling using a timer */
2004 if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
2005 !list_empty(&cfs_b->throttled_cfs_rq))
2006 start_cfs_slack_bandwidth(cfs_b);
2008 raw_spin_unlock(&cfs_b->lock);
2010 /* even if it's not valid for return we don't want to try again */
2011 cfs_rq->runtime_remaining -= slack_runtime;
2014 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2016 if (!cfs_bandwidth_used())
2019 if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
2022 __return_cfs_rq_runtime(cfs_rq);
2026 * This is done with a timer (instead of inline with bandwidth return) since
2027 * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
2029 static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
2031 u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
2034 /* confirm we're still not at a refresh boundary */
2035 if (runtime_refresh_within(cfs_b, min_bandwidth_expiration))
2038 raw_spin_lock(&cfs_b->lock);
2039 if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) {
2040 runtime = cfs_b->runtime;
2043 expires = cfs_b->runtime_expires;
2044 raw_spin_unlock(&cfs_b->lock);
2049 runtime = distribute_cfs_runtime(cfs_b, runtime, expires);
2051 raw_spin_lock(&cfs_b->lock);
2052 if (expires == cfs_b->runtime_expires)
2053 cfs_b->runtime = runtime;
2054 raw_spin_unlock(&cfs_b->lock);
2058 * When a group wakes up we want to make sure that its quota is not already
2059 * expired/exceeded, otherwise it may be allowed to steal additional ticks of
2060 * runtime as update_curr() throttling can not not trigger until it's on-rq.
2062 static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
2064 if (!cfs_bandwidth_used())
2067 /* an active group must be handled by the update_curr()->put() path */
2068 if (!cfs_rq->runtime_enabled || cfs_rq->curr)
2071 /* ensure the group is not already throttled */
2072 if (cfs_rq_throttled(cfs_rq))
2075 /* update runtime allocation */
2076 account_cfs_rq_runtime(cfs_rq, 0);
2077 if (cfs_rq->runtime_remaining <= 0)
2078 throttle_cfs_rq(cfs_rq);
2081 /* conditionally throttle active cfs_rq's from put_prev_entity() */
2082 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2084 if (!cfs_bandwidth_used())
2087 if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
2091 * it's possible for a throttled entity to be forced into a running
2092 * state (e.g. set_curr_task), in this case we're finished.
2094 if (cfs_rq_throttled(cfs_rq))
2097 throttle_cfs_rq(cfs_rq);
2100 static inline u64 default_cfs_period(void);
2101 static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun);
2102 static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b);
2104 static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
2106 struct cfs_bandwidth *cfs_b =
2107 container_of(timer, struct cfs_bandwidth, slack_timer);
2108 do_sched_cfs_slack_timer(cfs_b);
2110 return HRTIMER_NORESTART;
2113 static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
2115 struct cfs_bandwidth *cfs_b =
2116 container_of(timer, struct cfs_bandwidth, period_timer);
2122 now = hrtimer_cb_get_time(timer);
2123 overrun = hrtimer_forward(timer, now, cfs_b->period);
2128 idle = do_sched_cfs_period_timer(cfs_b, overrun);
2131 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
2134 void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2136 raw_spin_lock_init(&cfs_b->lock);
2138 cfs_b->quota = RUNTIME_INF;
2139 cfs_b->period = ns_to_ktime(default_cfs_period());
2141 INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
2142 hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
2143 cfs_b->period_timer.function = sched_cfs_period_timer;
2144 hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
2145 cfs_b->slack_timer.function = sched_cfs_slack_timer;
2148 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2150 cfs_rq->runtime_enabled = 0;
2151 INIT_LIST_HEAD(&cfs_rq->throttled_list);
2154 /* requires cfs_b->lock, may release to reprogram timer */
2155 void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2158 * The timer may be active because we're trying to set a new bandwidth
2159 * period or because we're racing with the tear-down path
2160 * (timer_active==0 becomes visible before the hrtimer call-back
2161 * terminates). In either case we ensure that it's re-programmed
2163 while (unlikely(hrtimer_active(&cfs_b->period_timer))) {
2164 raw_spin_unlock(&cfs_b->lock);
2165 /* ensure cfs_b->lock is available while we wait */
2166 hrtimer_cancel(&cfs_b->period_timer);
2168 raw_spin_lock(&cfs_b->lock);
2169 /* if someone else restarted the timer then we're done */
2170 if (cfs_b->timer_active)
2174 cfs_b->timer_active = 1;
2175 start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period);
2178 static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2180 hrtimer_cancel(&cfs_b->period_timer);
2181 hrtimer_cancel(&cfs_b->slack_timer);
2184 static void unthrottle_offline_cfs_rqs(struct rq *rq)
2186 struct cfs_rq *cfs_rq;
2188 for_each_leaf_cfs_rq(rq, cfs_rq) {
2189 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2191 if (!cfs_rq->runtime_enabled)
2195 * clock_task is not advancing so we just need to make sure
2196 * there's some valid quota amount
2198 cfs_rq->runtime_remaining = cfs_b->quota;
2199 if (cfs_rq_throttled(cfs_rq))
2200 unthrottle_cfs_rq(cfs_rq);
2204 #else /* CONFIG_CFS_BANDWIDTH */
2205 static __always_inline
2206 void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec) {}
2207 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2208 static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
2209 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2211 static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
2216 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
2221 static inline int throttled_lb_pair(struct task_group *tg,
2222 int src_cpu, int dest_cpu)
2227 void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
2229 #ifdef CONFIG_FAIR_GROUP_SCHED
2230 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2233 static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
2237 static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
2238 static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
2240 #endif /* CONFIG_CFS_BANDWIDTH */
2242 /**************************************************
2243 * CFS operations on tasks:
2246 #ifdef CONFIG_SCHED_HRTICK
2247 static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
2249 struct sched_entity *se = &p->se;
2250 struct cfs_rq *cfs_rq = cfs_rq_of(se);
2252 WARN_ON(task_rq(p) != rq);
2254 if (cfs_rq->nr_running > 1) {
2255 u64 slice = sched_slice(cfs_rq, se);
2256 u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
2257 s64 delta = slice - ran;
2266 * Don't schedule slices shorter than 10000ns, that just
2267 * doesn't make sense. Rely on vruntime for fairness.
2270 delta = max_t(s64, 10000LL, delta);
2272 hrtick_start(rq, delta);
2277 * called from enqueue/dequeue and updates the hrtick when the
2278 * current task is from our class and nr_running is low enough
2281 static void hrtick_update(struct rq *rq)
2283 struct task_struct *curr = rq->curr;
2285 if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class)
2288 if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
2289 hrtick_start_fair(rq, curr);
2291 #else /* !CONFIG_SCHED_HRTICK */
2293 hrtick_start_fair(struct rq *rq, struct task_struct *p)
2297 static inline void hrtick_update(struct rq *rq)
2303 * The enqueue_task method is called before nr_running is
2304 * increased. Here we update the fair scheduling stats and
2305 * then put the task into the rbtree:
2308 enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
2310 struct cfs_rq *cfs_rq;
2311 struct sched_entity *se = &p->se;
2313 for_each_sched_entity(se) {
2316 cfs_rq = cfs_rq_of(se);
2317 enqueue_entity(cfs_rq, se, flags);
2320 * end evaluation on encountering a throttled cfs_rq
2322 * note: in the case of encountering a throttled cfs_rq we will
2323 * post the final h_nr_running increment below.
2325 if (cfs_rq_throttled(cfs_rq))
2327 cfs_rq->h_nr_running++;
2329 flags = ENQUEUE_WAKEUP;
2332 for_each_sched_entity(se) {
2333 cfs_rq = cfs_rq_of(se);
2334 cfs_rq->h_nr_running++;
2336 if (cfs_rq_throttled(cfs_rq))
2339 update_cfs_load(cfs_rq, 0);
2340 update_cfs_shares(cfs_rq);
2348 static void set_next_buddy(struct sched_entity *se);
2351 * The dequeue_task method is called before nr_running is
2352 * decreased. We remove the task from the rbtree and
2353 * update the fair scheduling stats:
2355 static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
2357 struct cfs_rq *cfs_rq;
2358 struct sched_entity *se = &p->se;
2359 int task_sleep = flags & DEQUEUE_SLEEP;
2361 for_each_sched_entity(se) {
2362 cfs_rq = cfs_rq_of(se);
2363 dequeue_entity(cfs_rq, se, flags);
2366 * end evaluation on encountering a throttled cfs_rq
2368 * note: in the case of encountering a throttled cfs_rq we will
2369 * post the final h_nr_running decrement below.
2371 if (cfs_rq_throttled(cfs_rq))
2373 cfs_rq->h_nr_running--;
2375 /* Don't dequeue parent if it has other entities besides us */
2376 if (cfs_rq->load.weight) {
2378 * Bias pick_next to pick a task from this cfs_rq, as
2379 * p is sleeping when it is within its sched_slice.
2381 if (task_sleep && parent_entity(se))
2382 set_next_buddy(parent_entity(se));
2384 /* avoid re-evaluating load for this entity */
2385 se = parent_entity(se);
2388 flags |= DEQUEUE_SLEEP;
2391 for_each_sched_entity(se) {
2392 cfs_rq = cfs_rq_of(se);
2393 cfs_rq->h_nr_running--;
2395 if (cfs_rq_throttled(cfs_rq))
2398 update_cfs_load(cfs_rq, 0);
2399 update_cfs_shares(cfs_rq);
2408 /* Used instead of source_load when we know the type == 0 */
2409 static unsigned long weighted_cpuload(const int cpu)
2411 return cpu_rq(cpu)->load.weight;
2415 * Return a low guess at the load of a migration-source cpu weighted
2416 * according to the scheduling class and "nice" value.
2418 * We want to under-estimate the load of migration sources, to
2419 * balance conservatively.
2421 static unsigned long source_load(int cpu, int type)
2423 struct rq *rq = cpu_rq(cpu);
2424 unsigned long total = weighted_cpuload(cpu);
2426 if (type == 0 || !sched_feat(LB_BIAS))
2429 return min(rq->cpu_load[type-1], total);
2433 * Return a high guess at the load of a migration-target cpu weighted
2434 * according to the scheduling class and "nice" value.
2436 static unsigned long target_load(int cpu, int type)
2438 struct rq *rq = cpu_rq(cpu);
2439 unsigned long total = weighted_cpuload(cpu);
2441 if (type == 0 || !sched_feat(LB_BIAS))
2444 return max(rq->cpu_load[type-1], total);
2447 static unsigned long power_of(int cpu)
2449 return cpu_rq(cpu)->cpu_power;
2452 static unsigned long cpu_avg_load_per_task(int cpu)
2454 struct rq *rq = cpu_rq(cpu);
2455 unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
2458 return rq->load.weight / nr_running;
2464 static void task_waking_fair(struct task_struct *p)
2466 struct sched_entity *se = &p->se;
2467 struct cfs_rq *cfs_rq = cfs_rq_of(se);
2470 #ifndef CONFIG_64BIT
2471 u64 min_vruntime_copy;
2474 min_vruntime_copy = cfs_rq->min_vruntime_copy;
2476 min_vruntime = cfs_rq->min_vruntime;
2477 } while (min_vruntime != min_vruntime_copy);
2479 min_vruntime = cfs_rq->min_vruntime;
2482 se->vruntime -= min_vruntime;
2485 #ifdef CONFIG_FAIR_GROUP_SCHED
2487 * effective_load() calculates the load change as seen from the root_task_group
2489 * Adding load to a group doesn't make a group heavier, but can cause movement
2490 * of group shares between cpus. Assuming the shares were perfectly aligned one
2491 * can calculate the shift in shares.
2493 * Calculate the effective load difference if @wl is added (subtracted) to @tg
2494 * on this @cpu and results in a total addition (subtraction) of @wg to the
2495 * total group weight.
2497 * Given a runqueue weight distribution (rw_i) we can compute a shares
2498 * distribution (s_i) using:
2500 * s_i = rw_i / \Sum rw_j (1)
2502 * Suppose we have 4 CPUs and our @tg is a direct child of the root group and
2503 * has 7 equal weight tasks, distributed as below (rw_i), with the resulting
2504 * shares distribution (s_i):
2506 * rw_i = { 2, 4, 1, 0 }
2507 * s_i = { 2/7, 4/7, 1/7, 0 }
2509 * As per wake_affine() we're interested in the load of two CPUs (the CPU the
2510 * task used to run on and the CPU the waker is running on), we need to
2511 * compute the effect of waking a task on either CPU and, in case of a sync
2512 * wakeup, compute the effect of the current task going to sleep.
2514 * So for a change of @wl to the local @cpu with an overall group weight change
2515 * of @wl we can compute the new shares distribution (s'_i) using:
2517 * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2)
2519 * Suppose we're interested in CPUs 0 and 1, and want to compute the load
2520 * differences in waking a task to CPU 0. The additional task changes the
2521 * weight and shares distributions like:
2523 * rw'_i = { 3, 4, 1, 0 }
2524 * s'_i = { 3/8, 4/8, 1/8, 0 }
2526 * We can then compute the difference in effective weight by using:
2528 * dw_i = S * (s'_i - s_i) (3)
2530 * Where 'S' is the group weight as seen by its parent.
2532 * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7)
2533 * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 -
2534 * 4/7) times the weight of the group.
2536 static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
2538 struct sched_entity *se = tg->se[cpu];
2540 if (!tg->parent) /* the trivial, non-cgroup case */
2543 for_each_sched_entity(se) {
2549 * W = @wg + \Sum rw_j
2551 W = wg + calc_tg_weight(tg, se->my_q);
2556 w = se->my_q->load.weight + wl;
2559 * wl = S * s'_i; see (2)
2562 wl = (w * tg->shares) / W;
2567 * Per the above, wl is the new se->load.weight value; since
2568 * those are clipped to [MIN_SHARES, ...) do so now. See
2569 * calc_cfs_shares().
2571 if (wl < MIN_SHARES)
2575 * wl = dw_i = S * (s'_i - s_i); see (3)
2577 wl -= se->load.weight;
2580 * Recursively apply this logic to all parent groups to compute
2581 * the final effective load change on the root group. Since
2582 * only the @tg group gets extra weight, all parent groups can
2583 * only redistribute existing shares. @wl is the shift in shares
2584 * resulting from this level per the above.
2593 static inline unsigned long effective_load(struct task_group *tg, int cpu,
2594 unsigned long wl, unsigned long wg)
2601 static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
2603 s64 this_load, load;
2604 int idx, this_cpu, prev_cpu;
2605 unsigned long tl_per_task;
2606 struct task_group *tg;
2607 unsigned long weight;
2611 this_cpu = smp_processor_id();
2612 prev_cpu = task_cpu(p);
2613 load = source_load(prev_cpu, idx);
2614 this_load = target_load(this_cpu, idx);
2617 * If sync wakeup then subtract the (maximum possible)
2618 * effect of the currently running task from the load
2619 * of the current CPU:
2622 tg = task_group(current);
2623 weight = current->se.load.weight;
2625 this_load += effective_load(tg, this_cpu, -weight, -weight);
2626 load += effective_load(tg, prev_cpu, 0, -weight);
2630 weight = p->se.load.weight;
2633 * In low-load situations, where prev_cpu is idle and this_cpu is idle
2634 * due to the sync cause above having dropped this_load to 0, we'll
2635 * always have an imbalance, but there's really nothing you can do
2636 * about that, so that's good too.
2638 * Otherwise check if either cpus are near enough in load to allow this
2639 * task to be woken on this_cpu.
2641 if (this_load > 0) {
2642 s64 this_eff_load, prev_eff_load;
2644 this_eff_load = 100;
2645 this_eff_load *= power_of(prev_cpu);
2646 this_eff_load *= this_load +
2647 effective_load(tg, this_cpu, weight, weight);
2649 prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2;
2650 prev_eff_load *= power_of(this_cpu);
2651 prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight);
2653 balanced = this_eff_load <= prev_eff_load;
2658 * If the currently running task will sleep within
2659 * a reasonable amount of time then attract this newly
2662 if (sync && balanced)
2665 schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
2666 tl_per_task = cpu_avg_load_per_task(this_cpu);
2669 (this_load <= load &&
2670 this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
2672 * This domain has SD_WAKE_AFFINE and
2673 * p is cache cold in this domain, and
2674 * there is no bad imbalance.
2676 schedstat_inc(sd, ttwu_move_affine);
2677 schedstat_inc(p, se.statistics.nr_wakeups_affine);
2685 * find_idlest_group finds and returns the least busy CPU group within the
2688 static struct sched_group *
2689 find_idlest_group(struct sched_domain *sd, struct task_struct *p,
2690 int this_cpu, int load_idx)
2692 struct sched_group *idlest = NULL, *group = sd->groups;
2693 unsigned long min_load = ULONG_MAX, this_load = 0;
2694 int imbalance = 100 + (sd->imbalance_pct-100)/2;
2697 unsigned long load, avg_load;
2701 /* Skip over this group if it has no CPUs allowed */
2702 if (!cpumask_intersects(sched_group_cpus(group),
2703 tsk_cpus_allowed(p)))
2706 local_group = cpumask_test_cpu(this_cpu,
2707 sched_group_cpus(group));
2709 /* Tally up the load of all CPUs in the group */
2712 for_each_cpu(i, sched_group_cpus(group)) {
2713 /* Bias balancing toward cpus of our domain */
2715 load = source_load(i, load_idx);
2717 load = target_load(i, load_idx);
2722 /* Adjust by relative CPU power of the group */
2723 avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power;
2726 this_load = avg_load;
2727 } else if (avg_load < min_load) {
2728 min_load = avg_load;
2731 } while (group = group->next, group != sd->groups);
2733 if (!idlest || 100*this_load < imbalance*min_load)
2739 * find_idlest_cpu - find the idlest cpu among the cpus in group.
2742 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
2744 unsigned long load, min_load = ULONG_MAX;
2748 /* Traverse only the allowed CPUs */
2749 for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) {
2750 load = weighted_cpuload(i);
2752 if (load < min_load || (load == min_load && i == this_cpu)) {
2762 * Try and locate an idle CPU in the sched_domain.
2764 static int select_idle_sibling(struct task_struct *p, int target)
2766 int cpu = smp_processor_id();
2767 int prev_cpu = task_cpu(p);
2768 struct sched_domain *sd;
2769 struct sched_group *sg;
2773 * If the task is going to be woken-up on this cpu and if it is
2774 * already idle, then it is the right target.
2776 if (target == cpu && idle_cpu(cpu))
2780 * If the task is going to be woken-up on the cpu where it previously
2781 * ran and if it is currently idle, then it the right target.
2783 if (target == prev_cpu && idle_cpu(prev_cpu))
2787 * Otherwise, iterate the domains and find an elegible idle cpu.
2789 sd = rcu_dereference(per_cpu(sd_llc, target));
2790 for_each_lower_domain(sd) {
2793 if (!cpumask_intersects(sched_group_cpus(sg),
2794 tsk_cpus_allowed(p)))
2797 for_each_cpu(i, sched_group_cpus(sg)) {
2802 target = cpumask_first_and(sched_group_cpus(sg),
2803 tsk_cpus_allowed(p));
2807 } while (sg != sd->groups);
2814 * sched_balance_self: balance the current task (running on cpu) in domains
2815 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
2818 * Balance, ie. select the least loaded group.
2820 * Returns the target CPU number, or the same CPU if no balancing is needed.
2822 * preempt must be disabled.
2825 select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
2827 struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
2828 int cpu = smp_processor_id();
2829 int prev_cpu = task_cpu(p);
2831 int want_affine = 0;
2832 int sync = wake_flags & WF_SYNC;
2834 if (p->nr_cpus_allowed == 1)
2837 if (sd_flag & SD_BALANCE_WAKE) {
2838 if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
2844 for_each_domain(cpu, tmp) {
2845 if (!(tmp->flags & SD_LOAD_BALANCE))
2849 * If both cpu and prev_cpu are part of this domain,
2850 * cpu is a valid SD_WAKE_AFFINE target.
2852 if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
2853 cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
2858 if (tmp->flags & sd_flag)
2863 if (cpu != prev_cpu && wake_affine(affine_sd, p, sync))
2866 new_cpu = select_idle_sibling(p, prev_cpu);
2871 int load_idx = sd->forkexec_idx;
2872 struct sched_group *group;
2875 if (!(sd->flags & sd_flag)) {
2880 if (sd_flag & SD_BALANCE_WAKE)
2881 load_idx = sd->wake_idx;
2883 group = find_idlest_group(sd, p, cpu, load_idx);
2889 new_cpu = find_idlest_cpu(group, p, cpu);
2890 if (new_cpu == -1 || new_cpu == cpu) {
2891 /* Now try balancing at a lower domain level of cpu */
2896 /* Now try balancing at a lower domain level of new_cpu */
2898 weight = sd->span_weight;
2900 for_each_domain(cpu, tmp) {
2901 if (weight <= tmp->span_weight)
2903 if (tmp->flags & sd_flag)
2906 /* while loop will break here if sd == NULL */
2913 #endif /* CONFIG_SMP */
2915 static unsigned long
2916 wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
2918 unsigned long gran = sysctl_sched_wakeup_granularity;
2921 * Since its curr running now, convert the gran from real-time
2922 * to virtual-time in his units.
2924 * By using 'se' instead of 'curr' we penalize light tasks, so
2925 * they get preempted easier. That is, if 'se' < 'curr' then
2926 * the resulting gran will be larger, therefore penalizing the
2927 * lighter, if otoh 'se' > 'curr' then the resulting gran will
2928 * be smaller, again penalizing the lighter task.
2930 * This is especially important for buddies when the leftmost
2931 * task is higher priority than the buddy.
2933 return calc_delta_fair(gran, se);
2937 * Should 'se' preempt 'curr'.
2951 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
2953 s64 gran, vdiff = curr->vruntime - se->vruntime;
2958 gran = wakeup_gran(curr, se);
2965 static void set_last_buddy(struct sched_entity *se)
2967 if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
2970 for_each_sched_entity(se)
2971 cfs_rq_of(se)->last = se;
2974 static void set_next_buddy(struct sched_entity *se)
2976 if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
2979 for_each_sched_entity(se)
2980 cfs_rq_of(se)->next = se;
2983 static void set_skip_buddy(struct sched_entity *se)
2985 for_each_sched_entity(se)
2986 cfs_rq_of(se)->skip = se;
2990 * Preempt the current task with a newly woken task if needed:
2992 static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
2994 struct task_struct *curr = rq->curr;
2995 struct sched_entity *se = &curr->se, *pse = &p->se;
2996 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
2997 int scale = cfs_rq->nr_running >= sched_nr_latency;
2998 int next_buddy_marked = 0;
3000 if (unlikely(se == pse))
3004 * This is possible from callers such as move_task(), in which we
3005 * unconditionally check_prempt_curr() after an enqueue (which may have
3006 * lead to a throttle). This both saves work and prevents false
3007 * next-buddy nomination below.
3009 if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
3012 if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
3013 set_next_buddy(pse);
3014 next_buddy_marked = 1;
3018 * We can come here with TIF_NEED_RESCHED already set from new task
3021 * Note: this also catches the edge-case of curr being in a throttled
3022 * group (e.g. via set_curr_task), since update_curr() (in the
3023 * enqueue of curr) will have resulted in resched being set. This
3024 * prevents us from potentially nominating it as a false LAST_BUDDY
3027 if (test_tsk_need_resched(curr))
3030 /* Idle tasks are by definition preempted by non-idle tasks. */
3031 if (unlikely(curr->policy == SCHED_IDLE) &&
3032 likely(p->policy != SCHED_IDLE))
3036 * Batch and idle tasks do not preempt non-idle tasks (their preemption
3037 * is driven by the tick):
3039 if (unlikely(p->policy != SCHED_NORMAL))
3042 find_matching_se(&se, &pse);
3043 update_curr(cfs_rq_of(se));
3045 if (wakeup_preempt_entity(se, pse) == 1) {
3047 * Bias pick_next to pick the sched entity that is
3048 * triggering this preemption.
3050 if (!next_buddy_marked)
3051 set_next_buddy(pse);
3060 * Only set the backward buddy when the current task is still
3061 * on the rq. This can happen when a wakeup gets interleaved
3062 * with schedule on the ->pre_schedule() or idle_balance()
3063 * point, either of which can * drop the rq lock.
3065 * Also, during early boot the idle thread is in the fair class,
3066 * for obvious reasons its a bad idea to schedule back to it.
3068 if (unlikely(!se->on_rq || curr == rq->idle))
3071 if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
3075 static struct task_struct *pick_next_task_fair(struct rq *rq)
3077 struct task_struct *p;
3078 struct cfs_rq *cfs_rq = &rq->cfs;
3079 struct sched_entity *se;
3081 if (!cfs_rq->nr_running)
3085 se = pick_next_entity(cfs_rq);
3086 set_next_entity(cfs_rq, se);
3087 cfs_rq = group_cfs_rq(se);
3091 if (hrtick_enabled(rq))
3092 hrtick_start_fair(rq, p);
3098 * Account for a descheduled task:
3100 static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
3102 struct sched_entity *se = &prev->se;
3103 struct cfs_rq *cfs_rq;
3105 for_each_sched_entity(se) {
3106 cfs_rq = cfs_rq_of(se);
3107 put_prev_entity(cfs_rq, se);
3112 * sched_yield() is very simple
3114 * The magic of dealing with the ->skip buddy is in pick_next_entity.
3116 static void yield_task_fair(struct rq *rq)
3118 struct task_struct *curr = rq->curr;
3119 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
3120 struct sched_entity *se = &curr->se;
3123 * Are we the only task in the tree?
3125 if (unlikely(rq->nr_running == 1))
3128 clear_buddies(cfs_rq, se);
3130 if (curr->policy != SCHED_BATCH) {
3131 update_rq_clock(rq);
3133 * Update run-time statistics of the 'current'.
3135 update_curr(cfs_rq);
3137 * Tell update_rq_clock() that we've just updated,
3138 * so we don't do microscopic update in schedule()
3139 * and double the fastpath cost.
3141 rq->skip_clock_update = 1;
3147 static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt)
3149 struct sched_entity *se = &p->se;
3151 /* throttled hierarchies are not runnable */
3152 if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
3155 /* Tell the scheduler that we'd really like pse to run next. */
3158 yield_task_fair(rq);
3164 /**************************************************
3165 * Fair scheduling class load-balancing methods:
3168 static unsigned long __read_mostly max_load_balance_interval = HZ/10;
3170 #define LBF_ALL_PINNED 0x01
3171 #define LBF_NEED_BREAK 0x02
3172 #define LBF_SOME_PINNED 0x04
3175 struct sched_domain *sd;
3183 struct cpumask *dst_grpmask;
3185 enum cpu_idle_type idle;
3187 /* The set of CPUs under consideration for load-balancing */
3188 struct cpumask *cpus;
3193 unsigned int loop_break;
3194 unsigned int loop_max;
3198 * move_task - move a task from one runqueue to another runqueue.
3199 * Both runqueues must be locked.
3201 static void move_task(struct task_struct *p, struct lb_env *env)
3203 deactivate_task(env->src_rq, p, 0);
3204 set_task_cpu(p, env->dst_cpu);
3205 activate_task(env->dst_rq, p, 0);
3206 check_preempt_curr(env->dst_rq, p, 0);
3210 * Is this task likely cache-hot:
3213 task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
3217 if (p->sched_class != &fair_sched_class)
3220 if (unlikely(p->policy == SCHED_IDLE))
3224 * Buddy candidates are cache hot:
3226 if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running &&
3227 (&p->se == cfs_rq_of(&p->se)->next ||
3228 &p->se == cfs_rq_of(&p->se)->last))
3231 if (sysctl_sched_migration_cost == -1)
3233 if (sysctl_sched_migration_cost == 0)
3236 delta = now - p->se.exec_start;
3238 return delta < (s64)sysctl_sched_migration_cost;
3242 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
3245 int can_migrate_task(struct task_struct *p, struct lb_env *env)
3247 int tsk_cache_hot = 0;
3249 * We do not migrate tasks that are:
3250 * 1) running (obviously), or
3251 * 2) cannot be migrated to this CPU due to cpus_allowed, or
3252 * 3) are cache-hot on their current CPU.
3254 if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
3257 schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
3260 * Remember if this task can be migrated to any other cpu in
3261 * our sched_group. We may want to revisit it if we couldn't
3262 * meet load balance goals by pulling other tasks on src_cpu.
3264 * Also avoid computing new_dst_cpu if we have already computed
3265 * one in current iteration.
3267 if (!env->dst_grpmask || (env->flags & LBF_SOME_PINNED))
3270 new_dst_cpu = cpumask_first_and(env->dst_grpmask,
3271 tsk_cpus_allowed(p));
3272 if (new_dst_cpu < nr_cpu_ids) {
3273 env->flags |= LBF_SOME_PINNED;
3274 env->new_dst_cpu = new_dst_cpu;
3279 /* Record that we found atleast one task that could run on dst_cpu */
3280 env->flags &= ~LBF_ALL_PINNED;
3282 if (task_running(env->src_rq, p)) {
3283 schedstat_inc(p, se.statistics.nr_failed_migrations_running);
3288 * Aggressive migration if:
3289 * 1) task is cache cold, or
3290 * 2) too many balance attempts have failed.
3293 tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
3294 if (!tsk_cache_hot ||
3295 env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
3296 #ifdef CONFIG_SCHEDSTATS
3297 if (tsk_cache_hot) {
3298 schedstat_inc(env->sd, lb_hot_gained[env->idle]);
3299 schedstat_inc(p, se.statistics.nr_forced_migrations);
3305 if (tsk_cache_hot) {
3306 schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
3313 * move_one_task tries to move exactly one task from busiest to this_rq, as
3314 * part of active balancing operations within "domain".
3315 * Returns 1 if successful and 0 otherwise.
3317 * Called with both runqueues locked.
3319 static int move_one_task(struct lb_env *env)
3321 struct task_struct *p, *n;
3323 list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
3324 if (throttled_lb_pair(task_group(p), env->src_rq->cpu, env->dst_cpu))
3327 if (!can_migrate_task(p, env))
3332 * Right now, this is only the second place move_task()
3333 * is called, so we can safely collect move_task()
3334 * stats here rather than inside move_task().
3336 schedstat_inc(env->sd, lb_gained[env->idle]);
3342 static unsigned long task_h_load(struct task_struct *p);
3344 static const unsigned int sched_nr_migrate_break = 32;
3347 * move_tasks tries to move up to imbalance weighted load from busiest to
3348 * this_rq, as part of a balancing operation within domain "sd".
3349 * Returns 1 if successful and 0 otherwise.
3351 * Called with both runqueues locked.
3353 static int move_tasks(struct lb_env *env)
3355 struct list_head *tasks = &env->src_rq->cfs_tasks;
3356 struct task_struct *p;
3360 if (env->imbalance <= 0)
3363 while (!list_empty(tasks)) {
3364 p = list_first_entry(tasks, struct task_struct, se.group_node);
3367 /* We've more or less seen every task there is, call it quits */
3368 if (env->loop > env->loop_max)
3371 /* take a breather every nr_migrate tasks */
3372 if (env->loop > env->loop_break) {
3373 env->loop_break += sched_nr_migrate_break;
3374 env->flags |= LBF_NEED_BREAK;
3378 if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
3381 load = task_h_load(p);
3383 if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed)
3386 if ((load / 2) > env->imbalance)
3389 if (!can_migrate_task(p, env))
3394 env->imbalance -= load;
3396 #ifdef CONFIG_PREEMPT
3398 * NEWIDLE balancing is a source of latency, so preemptible
3399 * kernels will stop after the first task is pulled to minimize
3400 * the critical section.
3402 if (env->idle == CPU_NEWLY_IDLE)
3407 * We only want to steal up to the prescribed amount of
3410 if (env->imbalance <= 0)
3415 list_move_tail(&p->se.group_node, tasks);
3419 * Right now, this is one of only two places move_task() is called,
3420 * so we can safely collect move_task() stats here rather than
3421 * inside move_task().
3423 schedstat_add(env->sd, lb_gained[env->idle], pulled);
3428 #ifdef CONFIG_FAIR_GROUP_SCHED
3430 * update tg->load_weight by folding this cpu's load_avg
3432 static int update_shares_cpu(struct task_group *tg, int cpu)
3434 struct cfs_rq *cfs_rq;
3435 unsigned long flags;
3442 cfs_rq = tg->cfs_rq[cpu];
3444 raw_spin_lock_irqsave(&rq->lock, flags);
3446 update_rq_clock(rq);
3447 update_cfs_load(cfs_rq, 1);
3450 * We need to update shares after updating tg->load_weight in
3451 * order to adjust the weight of groups with long running tasks.
3453 update_cfs_shares(cfs_rq);
3455 raw_spin_unlock_irqrestore(&rq->lock, flags);
3460 static void update_shares(int cpu)
3462 struct cfs_rq *cfs_rq;
3463 struct rq *rq = cpu_rq(cpu);
3467 * Iterates the task_group tree in a bottom up fashion, see
3468 * list_add_leaf_cfs_rq() for details.
3470 for_each_leaf_cfs_rq(rq, cfs_rq) {
3471 /* throttled entities do not contribute to load */
3472 if (throttled_hierarchy(cfs_rq))
3475 update_shares_cpu(cfs_rq->tg, cpu);
3481 * Compute the cpu's hierarchical load factor for each task group.
3482 * This needs to be done in a top-down fashion because the load of a child
3483 * group is a fraction of its parents load.
3485 static int tg_load_down(struct task_group *tg, void *data)
3488 long cpu = (long)data;
3491 load = cpu_rq(cpu)->load.weight;
3493 load = tg->parent->cfs_rq[cpu]->h_load;
3494 load *= tg->se[cpu]->load.weight;
3495 load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
3498 tg->cfs_rq[cpu]->h_load = load;
3503 static void update_h_load(long cpu)
3505 struct rq *rq = cpu_rq(cpu);
3506 unsigned long now = jiffies;
3508 if (rq->h_load_throttle == now)
3511 rq->h_load_throttle = now;
3514 walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
3518 static unsigned long task_h_load(struct task_struct *p)
3520 struct cfs_rq *cfs_rq = task_cfs_rq(p);
3523 load = p->se.load.weight;
3524 load = div_u64(load * cfs_rq->h_load, cfs_rq->load.weight + 1);
3529 static inline void update_shares(int cpu)
3533 static inline void update_h_load(long cpu)
3537 static unsigned long task_h_load(struct task_struct *p)
3539 return p->se.load.weight;
3543 /********** Helpers for find_busiest_group ************************/
3545 * sd_lb_stats - Structure to store the statistics of a sched_domain
3546 * during load balancing.
3548 struct sd_lb_stats {
3549 struct sched_group *busiest; /* Busiest group in this sd */
3550 struct sched_group *this; /* Local group in this sd */
3551 unsigned long total_load; /* Total load of all groups in sd */
3552 unsigned long total_pwr; /* Total power of all groups in sd */
3553 unsigned long avg_load; /* Average load across all groups in sd */
3555 /** Statistics of this group */
3556 unsigned long this_load;
3557 unsigned long this_load_per_task;
3558 unsigned long this_nr_running;
3559 unsigned long this_has_capacity;
3560 unsigned int this_idle_cpus;
3562 /* Statistics of the busiest group */
3563 unsigned int busiest_idle_cpus;
3564 unsigned long max_load;
3565 unsigned long busiest_load_per_task;
3566 unsigned long busiest_nr_running;
3567 unsigned long busiest_group_capacity;
3568 unsigned long busiest_has_capacity;
3569 unsigned int busiest_group_weight;
3571 int group_imb; /* Is there imbalance in this sd */
3575 * sg_lb_stats - stats of a sched_group required for load_balancing
3577 struct sg_lb_stats {
3578 unsigned long avg_load; /*Avg load across the CPUs of the group */
3579 unsigned long group_load; /* Total load over the CPUs of the group */
3580 unsigned long sum_nr_running; /* Nr tasks running in the group */
3581 unsigned long sum_weighted_load; /* Weighted load of group's tasks */
3582 unsigned long group_capacity;
3583 unsigned long idle_cpus;
3584 unsigned long group_weight;
3585 int group_imb; /* Is there an imbalance in the group ? */
3586 int group_has_capacity; /* Is there extra capacity in the group? */
3590 * get_sd_load_idx - Obtain the load index for a given sched domain.
3591 * @sd: The sched_domain whose load_idx is to be obtained.
3592 * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
3594 static inline int get_sd_load_idx(struct sched_domain *sd,
3595 enum cpu_idle_type idle)
3601 load_idx = sd->busy_idx;
3604 case CPU_NEWLY_IDLE:
3605 load_idx = sd->newidle_idx;
3608 load_idx = sd->idle_idx;
3615 unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
3617 return SCHED_POWER_SCALE;
3620 unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
3622 return default_scale_freq_power(sd, cpu);
3625 unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
3627 unsigned long weight = sd->span_weight;
3628 unsigned long smt_gain = sd->smt_gain;
3635 unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
3637 return default_scale_smt_power(sd, cpu);
3640 unsigned long scale_rt_power(int cpu)
3642 struct rq *rq = cpu_rq(cpu);
3643 u64 total, available, age_stamp, avg;
3646 * Since we're reading these variables without serialization make sure
3647 * we read them once before doing sanity checks on them.
3649 age_stamp = ACCESS_ONCE(rq->age_stamp);
3650 avg = ACCESS_ONCE(rq->rt_avg);
3652 total = sched_avg_period() + (rq->clock - age_stamp);
3654 if (unlikely(total < avg)) {
3655 /* Ensures that power won't end up being negative */
3658 available = total - avg;
3661 if (unlikely((s64)total < SCHED_POWER_SCALE))
3662 total = SCHED_POWER_SCALE;
3664 total >>= SCHED_POWER_SHIFT;
3666 return div_u64(available, total);
3669 static void update_cpu_power(struct sched_domain *sd, int cpu)
3671 unsigned long weight = sd->span_weight;
3672 unsigned long power = SCHED_POWER_SCALE;
3673 struct sched_group *sdg = sd->groups;
3675 if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
3676 if (sched_feat(ARCH_POWER))
3677 power *= arch_scale_smt_power(sd, cpu);
3679 power *= default_scale_smt_power(sd, cpu);
3681 power >>= SCHED_POWER_SHIFT;
3684 sdg->sgp->power_orig = power;
3686 if (sched_feat(ARCH_POWER))
3687 power *= arch_scale_freq_power(sd, cpu);
3689 power *= default_scale_freq_power(sd, cpu);
3691 power >>= SCHED_POWER_SHIFT;
3693 power *= scale_rt_power(cpu);
3694 power >>= SCHED_POWER_SHIFT;
3699 cpu_rq(cpu)->cpu_power = power;
3700 sdg->sgp->power = power;
3703 void update_group_power(struct sched_domain *sd, int cpu)
3705 struct sched_domain *child = sd->child;
3706 struct sched_group *group, *sdg = sd->groups;
3707 unsigned long power;
3708 unsigned long interval;
3710 interval = msecs_to_jiffies(sd->balance_interval);
3711 interval = clamp(interval, 1UL, max_load_balance_interval);
3712 sdg->sgp->next_update = jiffies + interval;
3715 update_cpu_power(sd, cpu);
3721 if (child->flags & SD_OVERLAP) {
3723 * SD_OVERLAP domains cannot assume that child groups
3724 * span the current group.
3727 for_each_cpu(cpu, sched_group_cpus(sdg))
3728 power += power_of(cpu);
3731 * !SD_OVERLAP domains can assume that child groups
3732 * span the current group.
3735 group = child->groups;
3737 power += group->sgp->power;
3738 group = group->next;
3739 } while (group != child->groups);
3742 sdg->sgp->power_orig = sdg->sgp->power = power;
3746 * Try and fix up capacity for tiny siblings, this is needed when
3747 * things like SD_ASYM_PACKING need f_b_g to select another sibling
3748 * which on its own isn't powerful enough.
3750 * See update_sd_pick_busiest() and check_asym_packing().
3753 fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
3756 * Only siblings can have significantly less than SCHED_POWER_SCALE
3758 if (!(sd->flags & SD_SHARE_CPUPOWER))
3762 * If ~90% of the cpu_power is still there, we're good.
3764 if (group->sgp->power * 32 > group->sgp->power_orig * 29)
3771 * update_sg_lb_stats - Update sched_group's statistics for load balancing.
3772 * @env: The load balancing environment.
3773 * @group: sched_group whose statistics are to be updated.
3774 * @load_idx: Load index of sched_domain of this_cpu for load calc.
3775 * @local_group: Does group contain this_cpu.
3776 * @balance: Should we balance.
3777 * @sgs: variable to hold the statistics for this group.
3779 static inline void update_sg_lb_stats(struct lb_env *env,
3780 struct sched_group *group, int load_idx,
3781 int local_group, int *balance, struct sg_lb_stats *sgs)
3783 unsigned long nr_running, max_nr_running, min_nr_running;
3784 unsigned long load, max_cpu_load, min_cpu_load;
3785 unsigned int balance_cpu = -1, first_idle_cpu = 0;
3786 unsigned long avg_load_per_task = 0;
3790 balance_cpu = group_balance_cpu(group);
3792 /* Tally up the load of all CPUs in the group */
3794 min_cpu_load = ~0UL;
3796 min_nr_running = ~0UL;
3798 for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
3799 struct rq *rq = cpu_rq(i);
3801 nr_running = rq->nr_running;
3803 /* Bias balancing toward cpus of our domain */
3805 if (idle_cpu(i) && !first_idle_cpu &&
3806 cpumask_test_cpu(i, sched_group_mask(group))) {
3811 load = target_load(i, load_idx);
3813 load = source_load(i, load_idx);
3814 if (load > max_cpu_load)
3815 max_cpu_load = load;
3816 if (min_cpu_load > load)
3817 min_cpu_load = load;
3819 if (nr_running > max_nr_running)
3820 max_nr_running = nr_running;
3821 if (min_nr_running > nr_running)
3822 min_nr_running = nr_running;
3825 sgs->group_load += load;
3826 sgs->sum_nr_running += nr_running;
3827 sgs->sum_weighted_load += weighted_cpuload(i);
3833 * First idle cpu or the first cpu(busiest) in this sched group
3834 * is eligible for doing load balancing at this and above
3835 * domains. In the newly idle case, we will allow all the cpu's
3836 * to do the newly idle load balance.
3839 if (env->idle != CPU_NEWLY_IDLE) {
3840 if (balance_cpu != env->dst_cpu) {
3844 update_group_power(env->sd, env->dst_cpu);
3845 } else if (time_after_eq(jiffies, group->sgp->next_update))
3846 update_group_power(env->sd, env->dst_cpu);
3849 /* Adjust by relative CPU power of the group */
3850 sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;
3853 * Consider the group unbalanced when the imbalance is larger
3854 * than the average weight of a task.
3856 * APZ: with cgroup the avg task weight can vary wildly and
3857 * might not be a suitable number - should we keep a
3858 * normalized nr_running number somewhere that negates
3861 if (sgs->sum_nr_running)
3862 avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
3864 if ((max_cpu_load - min_cpu_load) >= avg_load_per_task &&
3865 (max_nr_running - min_nr_running) > 1)
3868 sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
3870 if (!sgs->group_capacity)
3871 sgs->group_capacity = fix_small_capacity(env->sd, group);
3872 sgs->group_weight = group->group_weight;
3874 if (sgs->group_capacity > sgs->sum_nr_running)
3875 sgs->group_has_capacity = 1;
3879 * update_sd_pick_busiest - return 1 on busiest group
3880 * @env: The load balancing environment.
3881 * @sds: sched_domain statistics
3882 * @sg: sched_group candidate to be checked for being the busiest
3883 * @sgs: sched_group statistics
3885 * Determine if @sg is a busier group than the previously selected
3888 static bool update_sd_pick_busiest(struct lb_env *env,
3889 struct sd_lb_stats *sds,
3890 struct sched_group *sg,
3891 struct sg_lb_stats *sgs)
3893 if (sgs->avg_load <= sds->max_load)
3896 if (sgs->sum_nr_running > sgs->group_capacity)
3903 * ASYM_PACKING needs to move all the work to the lowest
3904 * numbered CPUs in the group, therefore mark all groups
3905 * higher than ourself as busy.
3907 if ((env->sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running &&
3908 env->dst_cpu < group_first_cpu(sg)) {
3912 if (group_first_cpu(sds->busiest) > group_first_cpu(sg))
3920 * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
3921 * @env: The load balancing environment.
3922 * @balance: Should we balance.
3923 * @sds: variable to hold the statistics for this sched_domain.
3925 static inline void update_sd_lb_stats(struct lb_env *env,
3926 int *balance, struct sd_lb_stats *sds)
3928 struct sched_domain *child = env->sd->child;
3929 struct sched_group *sg = env->sd->groups;
3930 struct sg_lb_stats sgs;
3931 int load_idx, prefer_sibling = 0;
3933 if (child && child->flags & SD_PREFER_SIBLING)
3936 load_idx = get_sd_load_idx(env->sd, env->idle);
3941 local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg));
3942 memset(&sgs, 0, sizeof(sgs));
3943 update_sg_lb_stats(env, sg, load_idx, local_group, balance, &sgs);
3945 if (local_group && !(*balance))
3948 sds->total_load += sgs.group_load;
3949 sds->total_pwr += sg->sgp->power;
3952 * In case the child domain prefers tasks go to siblings
3953 * first, lower the sg capacity to one so that we'll try
3954 * and move all the excess tasks away. We lower the capacity
3955 * of a group only if the local group has the capacity to fit
3956 * these excess tasks, i.e. nr_running < group_capacity. The
3957 * extra check prevents the case where you always pull from the
3958 * heaviest group when it is already under-utilized (possible
3959 * with a large weight task outweighs the tasks on the system).
3961 if (prefer_sibling && !local_group && sds->this_has_capacity)
3962 sgs.group_capacity = min(sgs.group_capacity, 1UL);
3965 sds->this_load = sgs.avg_load;
3967 sds->this_nr_running = sgs.sum_nr_running;
3968 sds->this_load_per_task = sgs.sum_weighted_load;
3969 sds->this_has_capacity = sgs.group_has_capacity;
3970 sds->this_idle_cpus = sgs.idle_cpus;
3971 } else if (update_sd_pick_busiest(env, sds, sg, &sgs)) {
3972 sds->max_load = sgs.avg_load;
3974 sds->busiest_nr_running = sgs.sum_nr_running;
3975 sds->busiest_idle_cpus = sgs.idle_cpus;
3976 sds->busiest_group_capacity = sgs.group_capacity;
3977 sds->busiest_load_per_task = sgs.sum_weighted_load;
3978 sds->busiest_has_capacity = sgs.group_has_capacity;
3979 sds->busiest_group_weight = sgs.group_weight;
3980 sds->group_imb = sgs.group_imb;
3984 } while (sg != env->sd->groups);
3988 * check_asym_packing - Check to see if the group is packed into the
3991 * This is primarily intended to used at the sibling level. Some
3992 * cores like POWER7 prefer to use lower numbered SMT threads. In the
3993 * case of POWER7, it can move to lower SMT modes only when higher
3994 * threads are idle. When in lower SMT modes, the threads will
3995 * perform better since they share less core resources. Hence when we
3996 * have idle threads, we want them to be the higher ones.
3998 * This packing function is run on idle threads. It checks to see if
3999 * the busiest CPU in this domain (core in the P7 case) has a higher
4000 * CPU number than the packing function is being run on. Here we are
4001 * assuming lower CPU number will be equivalent to lower a SMT thread
4004 * Returns 1 when packing is required and a task should be moved to
4005 * this CPU. The amount of the imbalance is returned in *imbalance.
4007 * @env: The load balancing environment.
4008 * @sds: Statistics of the sched_domain which is to be packed
4010 static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
4014 if (!(env->sd->flags & SD_ASYM_PACKING))
4020 busiest_cpu = group_first_cpu(sds->busiest);
4021 if (env->dst_cpu > busiest_cpu)
4024 env->imbalance = DIV_ROUND_CLOSEST(
4025 sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE);
4031 * fix_small_imbalance - Calculate the minor imbalance that exists
4032 * amongst the groups of a sched_domain, during
4034 * @env: The load balancing environment.
4035 * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
4038 void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
4040 unsigned long tmp, pwr_now = 0, pwr_move = 0;
4041 unsigned int imbn = 2;
4042 unsigned long scaled_busy_load_per_task;
4044 if (sds->this_nr_running) {
4045 sds->this_load_per_task /= sds->this_nr_running;
4046 if (sds->busiest_load_per_task >
4047 sds->this_load_per_task)
4050 sds->this_load_per_task =
4051 cpu_avg_load_per_task(env->dst_cpu);
4054 scaled_busy_load_per_task = sds->busiest_load_per_task
4055 * SCHED_POWER_SCALE;
4056 scaled_busy_load_per_task /= sds->busiest->sgp->power;
4058 if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
4059 (scaled_busy_load_per_task * imbn)) {
4060 env->imbalance = sds->busiest_load_per_task;
4065 * OK, we don't have enough imbalance to justify moving tasks,
4066 * however we may be able to increase total CPU power used by
4070 pwr_now += sds->busiest->sgp->power *
4071 min(sds->busiest_load_per_task, sds->max_load);
4072 pwr_now += sds->this->sgp->power *
4073 min(sds->this_load_per_task, sds->this_load);
4074 pwr_now /= SCHED_POWER_SCALE;
4076 /* Amount of load we'd subtract */
4077 tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
4078 sds->busiest->sgp->power;
4079 if (sds->max_load > tmp)
4080 pwr_move += sds->busiest->sgp->power *
4081 min(sds->busiest_load_per_task, sds->max_load - tmp);
4083 /* Amount of load we'd add */
4084 if (sds->max_load * sds->busiest->sgp->power <
4085 sds->busiest_load_per_task * SCHED_POWER_SCALE)
4086 tmp = (sds->max_load * sds->busiest->sgp->power) /
4087 sds->this->sgp->power;
4089 tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
4090 sds->this->sgp->power;
4091 pwr_move += sds->this->sgp->power *
4092 min(sds->this_load_per_task, sds->this_load + tmp);
4093 pwr_move /= SCHED_POWER_SCALE;
4095 /* Move if we gain throughput */
4096 if (pwr_move > pwr_now)
4097 env->imbalance = sds->busiest_load_per_task;
4101 * calculate_imbalance - Calculate the amount of imbalance present within the
4102 * groups of a given sched_domain during load balance.
4103 * @env: load balance environment
4104 * @sds: statistics of the sched_domain whose imbalance is to be calculated.
4106 static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
4108 unsigned long max_pull, load_above_capacity = ~0UL;
4110 sds->busiest_load_per_task /= sds->busiest_nr_running;
4111 if (sds->group_imb) {
4112 sds->busiest_load_per_task =
4113 min(sds->busiest_load_per_task, sds->avg_load);
4117 * In the presence of smp nice balancing, certain scenarios can have
4118 * max load less than avg load(as we skip the groups at or below
4119 * its cpu_power, while calculating max_load..)
4121 if (sds->max_load < sds->avg_load) {
4123 return fix_small_imbalance(env, sds);
4126 if (!sds->group_imb) {
4128 * Don't want to pull so many tasks that a group would go idle.
4130 load_above_capacity = (sds->busiest_nr_running -
4131 sds->busiest_group_capacity);
4133 load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
4135 load_above_capacity /= sds->busiest->sgp->power;
4139 * We're trying to get all the cpus to the average_load, so we don't
4140 * want to push ourselves above the average load, nor do we wish to
4141 * reduce the max loaded cpu below the average load. At the same time,
4142 * we also don't want to reduce the group load below the group capacity
4143 * (so that we can implement power-savings policies etc). Thus we look
4144 * for the minimum possible imbalance.
4145 * Be careful of negative numbers as they'll appear as very large values
4146 * with unsigned longs.
4148 max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);
4150 /* How much load to actually move to equalise the imbalance */
4151 env->imbalance = min(max_pull * sds->busiest->sgp->power,
4152 (sds->avg_load - sds->this_load) * sds->this->sgp->power)
4153 / SCHED_POWER_SCALE;
4156 * if *imbalance is less than the average load per runnable task
4157 * there is no guarantee that any tasks will be moved so we'll have
4158 * a think about bumping its value to force at least one task to be
4161 if (env->imbalance < sds->busiest_load_per_task)
4162 return fix_small_imbalance(env, sds);
4166 /******* find_busiest_group() helpers end here *********************/
4169 * find_busiest_group - Returns the busiest group within the sched_domain
4170 * if there is an imbalance. If there isn't an imbalance, and
4171 * the user has opted for power-savings, it returns a group whose
4172 * CPUs can be put to idle by rebalancing those tasks elsewhere, if
4173 * such a group exists.
4175 * Also calculates the amount of weighted load which should be moved
4176 * to restore balance.
4178 * @env: The load balancing environment.
4179 * @balance: Pointer to a variable indicating if this_cpu
4180 * is the appropriate cpu to perform load balancing at this_level.
4182 * Returns: - the busiest group if imbalance exists.
4183 * - If no imbalance and user has opted for power-savings balance,
4184 * return the least loaded group whose CPUs can be
4185 * put to idle by rebalancing its tasks onto our group.
4187 static struct sched_group *
4188 find_busiest_group(struct lb_env *env, int *balance)
4190 struct sd_lb_stats sds;
4192 memset(&sds, 0, sizeof(sds));
4195 * Compute the various statistics relavent for load balancing at
4198 update_sd_lb_stats(env, balance, &sds);
4201 * this_cpu is not the appropriate cpu to perform load balancing at
4207 if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) &&
4208 check_asym_packing(env, &sds))
4211 /* There is no busy sibling group to pull tasks from */
4212 if (!sds.busiest || sds.busiest_nr_running == 0)
4215 sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
4218 * If the busiest group is imbalanced the below checks don't
4219 * work because they assumes all things are equal, which typically
4220 * isn't true due to cpus_allowed constraints and the like.
4225 /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
4226 if (env->idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
4227 !sds.busiest_has_capacity)
4231 * If the local group is more busy than the selected busiest group
4232 * don't try and pull any tasks.
4234 if (sds.this_load >= sds.max_load)
4238 * Don't pull any tasks if this group is already above the domain
4241 if (sds.this_load >= sds.avg_load)
4244 if (env->idle == CPU_IDLE) {
4246 * This cpu is idle. If the busiest group load doesn't
4247 * have more tasks than the number of available cpu's and
4248 * there is no imbalance between this and busiest group
4249 * wrt to idle cpu's, it is balanced.
4251 if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) &&
4252 sds.busiest_nr_running <= sds.busiest_group_weight)
4256 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
4257 * imbalance_pct to be conservative.
4259 if (100 * sds.max_load <= env->sd->imbalance_pct * sds.this_load)
4264 /* Looks like there is an imbalance. Compute it */
4265 calculate_imbalance(env, &sds);
4275 * find_busiest_queue - find the busiest runqueue among the cpus in group.
4277 static struct rq *find_busiest_queue(struct lb_env *env,
4278 struct sched_group *group)
4280 struct rq *busiest = NULL, *rq;
4281 unsigned long max_load = 0;
4284 for_each_cpu(i, sched_group_cpus(group)) {
4285 unsigned long power = power_of(i);
4286 unsigned long capacity = DIV_ROUND_CLOSEST(power,
4291 capacity = fix_small_capacity(env->sd, group);
4293 if (!cpumask_test_cpu(i, env->cpus))
4297 wl = weighted_cpuload(i);
4300 * When comparing with imbalance, use weighted_cpuload()
4301 * which is not scaled with the cpu power.
4303 if (capacity && rq->nr_running == 1 && wl > env->imbalance)
4307 * For the load comparisons with the other cpu's, consider
4308 * the weighted_cpuload() scaled with the cpu power, so that
4309 * the load can be moved away from the cpu that is potentially
4310 * running at a lower capacity.
4312 wl = (wl * SCHED_POWER_SCALE) / power;
4314 if (wl > max_load) {
4324 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
4325 * so long as it is large enough.
4327 #define MAX_PINNED_INTERVAL 512
4329 /* Working cpumask for load_balance and load_balance_newidle. */
4330 DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
4332 static int need_active_balance(struct lb_env *env)
4334 struct sched_domain *sd = env->sd;
4336 if (env->idle == CPU_NEWLY_IDLE) {
4339 * ASYM_PACKING needs to force migrate tasks from busy but
4340 * higher numbered CPUs in order to pack all tasks in the
4341 * lowest numbered CPUs.
4343 if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu)
4347 return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
4350 static int active_load_balance_cpu_stop(void *data);
4353 * Check this_cpu to ensure it is balanced within domain. Attempt to move
4354 * tasks if there is an imbalance.
4356 static int load_balance(int this_cpu, struct rq *this_rq,
4357 struct sched_domain *sd, enum cpu_idle_type idle,
4360 int ld_moved, cur_ld_moved, active_balance = 0;
4361 int lb_iterations, max_lb_iterations;
4362 struct sched_group *group;
4364 unsigned long flags;
4365 struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
4367 struct lb_env env = {
4369 .dst_cpu = this_cpu,
4371 .dst_grpmask = sched_group_cpus(sd->groups),
4373 .loop_break = sched_nr_migrate_break,
4377 cpumask_copy(cpus, cpu_active_mask);
4378 max_lb_iterations = cpumask_weight(env.dst_grpmask);
4380 schedstat_inc(sd, lb_count[idle]);
4383 group = find_busiest_group(&env, balance);
4389 schedstat_inc(sd, lb_nobusyg[idle]);
4393 busiest = find_busiest_queue(&env, group);
4395 schedstat_inc(sd, lb_nobusyq[idle]);
4399 BUG_ON(busiest == env.dst_rq);
4401 schedstat_add(sd, lb_imbalance[idle], env.imbalance);
4405 if (busiest->nr_running > 1) {
4407 * Attempt to move tasks. If find_busiest_group has found
4408 * an imbalance but busiest->nr_running <= 1, the group is
4409 * still unbalanced. ld_moved simply stays zero, so it is
4410 * correctly treated as an imbalance.
4412 env.flags |= LBF_ALL_PINNED;
4413 env.src_cpu = busiest->cpu;
4414 env.src_rq = busiest;
4415 env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running);
4417 update_h_load(env.src_cpu);
4419 local_irq_save(flags);
4420 double_rq_lock(env.dst_rq, busiest);
4423 * cur_ld_moved - load moved in current iteration
4424 * ld_moved - cumulative load moved across iterations
4426 cur_ld_moved = move_tasks(&env);
4427 ld_moved += cur_ld_moved;
4428 double_rq_unlock(env.dst_rq, busiest);
4429 local_irq_restore(flags);
4431 if (env.flags & LBF_NEED_BREAK) {
4432 env.flags &= ~LBF_NEED_BREAK;
4437 * some other cpu did the load balance for us.
4439 if (cur_ld_moved && env.dst_cpu != smp_processor_id())
4440 resched_cpu(env.dst_cpu);
4443 * Revisit (affine) tasks on src_cpu that couldn't be moved to
4444 * us and move them to an alternate dst_cpu in our sched_group
4445 * where they can run. The upper limit on how many times we
4446 * iterate on same src_cpu is dependent on number of cpus in our
4449 * This changes load balance semantics a bit on who can move
4450 * load to a given_cpu. In addition to the given_cpu itself
4451 * (or a ilb_cpu acting on its behalf where given_cpu is
4452 * nohz-idle), we now have balance_cpu in a position to move
4453 * load to given_cpu. In rare situations, this may cause
4454 * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
4455 * _independently_ and at _same_ time to move some load to
4456 * given_cpu) causing exceess load to be moved to given_cpu.
4457 * This however should not happen so much in practice and
4458 * moreover subsequent load balance cycles should correct the
4459 * excess load moved.
4461 if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0 &&
4462 lb_iterations++ < max_lb_iterations) {
4464 env.dst_rq = cpu_rq(env.new_dst_cpu);
4465 env.dst_cpu = env.new_dst_cpu;
4466 env.flags &= ~LBF_SOME_PINNED;
4468 env.loop_break = sched_nr_migrate_break;
4470 * Go back to "more_balance" rather than "redo" since we
4471 * need to continue with same src_cpu.
4476 /* All tasks on this runqueue were pinned by CPU affinity */
4477 if (unlikely(env.flags & LBF_ALL_PINNED)) {
4478 cpumask_clear_cpu(cpu_of(busiest), cpus);
4479 if (!cpumask_empty(cpus)) {
4481 env.loop_break = sched_nr_migrate_break;
4489 schedstat_inc(sd, lb_failed[idle]);
4491 * Increment the failure counter only on periodic balance.
4492 * We do not want newidle balance, which can be very
4493 * frequent, pollute the failure counter causing
4494 * excessive cache_hot migrations and active balances.
4496 if (idle != CPU_NEWLY_IDLE)
4497 sd->nr_balance_failed++;
4499 if (need_active_balance(&env)) {
4500 raw_spin_lock_irqsave(&busiest->lock, flags);
4502 /* don't kick the active_load_balance_cpu_stop,
4503 * if the curr task on busiest cpu can't be
4506 if (!cpumask_test_cpu(this_cpu,
4507 tsk_cpus_allowed(busiest->curr))) {
4508 raw_spin_unlock_irqrestore(&busiest->lock,
4510 env.flags |= LBF_ALL_PINNED;
4511 goto out_one_pinned;
4515 * ->active_balance synchronizes accesses to
4516 * ->active_balance_work. Once set, it's cleared
4517 * only after active load balance is finished.
4519 if (!busiest->active_balance) {
4520 busiest->active_balance = 1;
4521 busiest->push_cpu = this_cpu;
4524 raw_spin_unlock_irqrestore(&busiest->lock, flags);
4526 if (active_balance) {
4527 stop_one_cpu_nowait(cpu_of(busiest),
4528 active_load_balance_cpu_stop, busiest,
4529 &busiest->active_balance_work);
4533 * We've kicked active balancing, reset the failure
4536 sd->nr_balance_failed = sd->cache_nice_tries+1;
4539 sd->nr_balance_failed = 0;
4541 if (likely(!active_balance)) {
4542 /* We were unbalanced, so reset the balancing interval */
4543 sd->balance_interval = sd->min_interval;
4546 * If we've begun active balancing, start to back off. This
4547 * case may not be covered by the all_pinned logic if there
4548 * is only 1 task on the busy runqueue (because we don't call
4551 if (sd->balance_interval < sd->max_interval)
4552 sd->balance_interval *= 2;
4558 schedstat_inc(sd, lb_balanced[idle]);
4560 sd->nr_balance_failed = 0;
4563 /* tune up the balancing interval */
4564 if (((env.flags & LBF_ALL_PINNED) &&
4565 sd->balance_interval < MAX_PINNED_INTERVAL) ||
4566 (sd->balance_interval < sd->max_interval))
4567 sd->balance_interval *= 2;
4575 * idle_balance is called by schedule() if this_cpu is about to become
4576 * idle. Attempts to pull tasks from other CPUs.
4578 void idle_balance(int this_cpu, struct rq *this_rq)
4580 struct sched_domain *sd;
4581 int pulled_task = 0;
4582 unsigned long next_balance = jiffies + HZ;
4584 this_rq->idle_stamp = this_rq->clock;
4586 if (this_rq->avg_idle < sysctl_sched_migration_cost)
4590 * Drop the rq->lock, but keep IRQ/preempt disabled.
4592 raw_spin_unlock(&this_rq->lock);
4594 update_shares(this_cpu);
4596 for_each_domain(this_cpu, sd) {
4597 unsigned long interval;
4600 if (!(sd->flags & SD_LOAD_BALANCE))
4603 if (sd->flags & SD_BALANCE_NEWIDLE) {
4604 /* If we've pulled tasks over stop searching: */
4605 pulled_task = load_balance(this_cpu, this_rq,
4606 sd, CPU_NEWLY_IDLE, &balance);
4609 interval = msecs_to_jiffies(sd->balance_interval);
4610 if (time_after(next_balance, sd->last_balance + interval))
4611 next_balance = sd->last_balance + interval;
4613 this_rq->idle_stamp = 0;
4619 raw_spin_lock(&this_rq->lock);
4621 if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
4623 * We are going idle. next_balance may be set based on
4624 * a busy processor. So reset next_balance.
4626 this_rq->next_balance = next_balance;
4631 * active_load_balance_cpu_stop is run by cpu stopper. It pushes
4632 * running tasks off the busiest CPU onto idle CPUs. It requires at
4633 * least 1 task to be running on each physical CPU where possible, and
4634 * avoids physical / logical imbalances.
4636 static int active_load_balance_cpu_stop(void *data)
4638 struct rq *busiest_rq = data;
4639 int busiest_cpu = cpu_of(busiest_rq);
4640 int target_cpu = busiest_rq->push_cpu;
4641 struct rq *target_rq = cpu_rq(target_cpu);
4642 struct sched_domain *sd;
4644 raw_spin_lock_irq(&busiest_rq->lock);
4646 /* make sure the requested cpu hasn't gone down in the meantime */
4647 if (unlikely(busiest_cpu != smp_processor_id() ||
4648 !busiest_rq->active_balance))
4651 /* Is there any task to move? */
4652 if (busiest_rq->nr_running <= 1)
4656 * This condition is "impossible", if it occurs
4657 * we need to fix it. Originally reported by
4658 * Bjorn Helgaas on a 128-cpu setup.
4660 BUG_ON(busiest_rq == target_rq);
4662 /* move a task from busiest_rq to target_rq */
4663 double_lock_balance(busiest_rq, target_rq);
4665 /* Search for an sd spanning us and the target CPU. */
4667 for_each_domain(target_cpu, sd) {
4668 if ((sd->flags & SD_LOAD_BALANCE) &&
4669 cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
4674 struct lb_env env = {
4676 .dst_cpu = target_cpu,
4677 .dst_rq = target_rq,
4678 .src_cpu = busiest_rq->cpu,
4679 .src_rq = busiest_rq,
4683 schedstat_inc(sd, alb_count);
4685 if (move_one_task(&env))
4686 schedstat_inc(sd, alb_pushed);
4688 schedstat_inc(sd, alb_failed);
4691 double_unlock_balance(busiest_rq, target_rq);
4693 busiest_rq->active_balance = 0;
4694 raw_spin_unlock_irq(&busiest_rq->lock);
4700 * idle load balancing details
4701 * - When one of the busy CPUs notice that there may be an idle rebalancing
4702 * needed, they will kick the idle load balancer, which then does idle
4703 * load balancing for all the idle CPUs.
4706 cpumask_var_t idle_cpus_mask;
4708 unsigned long next_balance; /* in jiffy units */
4709 } nohz ____cacheline_aligned;
4711 static inline int find_new_ilb(int call_cpu)
4713 int ilb = cpumask_first(nohz.idle_cpus_mask);
4715 if (ilb < nr_cpu_ids && idle_cpu(ilb))
4722 * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
4723 * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
4724 * CPU (if there is one).
4726 static void nohz_balancer_kick(int cpu)
4730 nohz.next_balance++;
4732 ilb_cpu = find_new_ilb(cpu);
4734 if (ilb_cpu >= nr_cpu_ids)
4737 if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu)))
4740 * Use smp_send_reschedule() instead of resched_cpu().
4741 * This way we generate a sched IPI on the target cpu which
4742 * is idle. And the softirq performing nohz idle load balance
4743 * will be run before returning from the IPI.
4745 smp_send_reschedule(ilb_cpu);
4749 static inline void nohz_balance_exit_idle(int cpu)
4751 if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
4752 cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
4753 atomic_dec(&nohz.nr_cpus);
4754 clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
4758 static inline void set_cpu_sd_state_busy(void)
4760 struct sched_domain *sd;
4761 int cpu = smp_processor_id();
4763 if (!test_bit(NOHZ_IDLE, nohz_flags(cpu)))
4765 clear_bit(NOHZ_IDLE, nohz_flags(cpu));
4768 for_each_domain(cpu, sd)
4769 atomic_inc(&sd->groups->sgp->nr_busy_cpus);
4773 void set_cpu_sd_state_idle(void)
4775 struct sched_domain *sd;
4776 int cpu = smp_processor_id();
4778 if (test_bit(NOHZ_IDLE, nohz_flags(cpu)))
4780 set_bit(NOHZ_IDLE, nohz_flags(cpu));
4783 for_each_domain(cpu, sd)
4784 atomic_dec(&sd->groups->sgp->nr_busy_cpus);
4789 * This routine will record that the cpu is going idle with tick stopped.
4790 * This info will be used in performing idle load balancing in the future.
4792 void nohz_balance_enter_idle(int cpu)
4795 * If this cpu is going down, then nothing needs to be done.
4797 if (!cpu_active(cpu))
4800 if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
4803 cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
4804 atomic_inc(&nohz.nr_cpus);
4805 set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
4808 static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
4809 unsigned long action, void *hcpu)
4811 switch (action & ~CPU_TASKS_FROZEN) {
4813 nohz_balance_exit_idle(smp_processor_id());
4821 static DEFINE_SPINLOCK(balancing);
4824 * Scale the max load_balance interval with the number of CPUs in the system.
4825 * This trades load-balance latency on larger machines for less cross talk.
4827 void update_max_interval(void)
4829 max_load_balance_interval = HZ*num_online_cpus()/10;
4833 * It checks each scheduling domain to see if it is due to be balanced,
4834 * and initiates a balancing operation if so.
4836 * Balancing parameters are set up in arch_init_sched_domains.
4838 static void rebalance_domains(int cpu, enum cpu_idle_type idle)
4841 struct rq *rq = cpu_rq(cpu);
4842 unsigned long interval;
4843 struct sched_domain *sd;
4844 /* Earliest time when we have to do rebalance again */
4845 unsigned long next_balance = jiffies + 60*HZ;
4846 int update_next_balance = 0;
4852 for_each_domain(cpu, sd) {
4853 if (!(sd->flags & SD_LOAD_BALANCE))
4856 interval = sd->balance_interval;
4857 if (idle != CPU_IDLE)
4858 interval *= sd->busy_factor;
4860 /* scale ms to jiffies */
4861 interval = msecs_to_jiffies(interval);
4862 interval = clamp(interval, 1UL, max_load_balance_interval);
4864 need_serialize = sd->flags & SD_SERIALIZE;
4866 if (need_serialize) {
4867 if (!spin_trylock(&balancing))
4871 if (time_after_eq(jiffies, sd->last_balance + interval)) {
4872 if (load_balance(cpu, rq, sd, idle, &balance)) {
4874 * We've pulled tasks over so either we're no
4877 idle = CPU_NOT_IDLE;
4879 sd->last_balance = jiffies;
4882 spin_unlock(&balancing);
4884 if (time_after(next_balance, sd->last_balance + interval)) {
4885 next_balance = sd->last_balance + interval;
4886 update_next_balance = 1;
4890 * Stop the load balance at this level. There is another
4891 * CPU in our sched group which is doing load balancing more
4900 * next_balance will be updated only when there is a need.
4901 * When the cpu is attached to null domain for ex, it will not be
4904 if (likely(update_next_balance))
4905 rq->next_balance = next_balance;
4910 * In CONFIG_NO_HZ case, the idle balance kickee will do the
4911 * rebalancing for all the cpus for whom scheduler ticks are stopped.
4913 static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle)
4915 struct rq *this_rq = cpu_rq(this_cpu);
4919 if (idle != CPU_IDLE ||
4920 !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
4923 for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
4924 if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
4928 * If this cpu gets work to do, stop the load balancing
4929 * work being done for other cpus. Next load
4930 * balancing owner will pick it up.
4935 rq = cpu_rq(balance_cpu);
4937 raw_spin_lock_irq(&rq->lock);
4938 update_rq_clock(rq);
4939 update_idle_cpu_load(rq);
4940 raw_spin_unlock_irq(&rq->lock);
4942 rebalance_domains(balance_cpu, CPU_IDLE);
4944 if (time_after(this_rq->next_balance, rq->next_balance))
4945 this_rq->next_balance = rq->next_balance;
4947 nohz.next_balance = this_rq->next_balance;
4949 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu));
4953 * Current heuristic for kicking the idle load balancer in the presence
4954 * of an idle cpu is the system.
4955 * - This rq has more than one task.
4956 * - At any scheduler domain level, this cpu's scheduler group has multiple
4957 * busy cpu's exceeding the group's power.
4958 * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
4959 * domain span are idle.
4961 static inline int nohz_kick_needed(struct rq *rq, int cpu)
4963 unsigned long now = jiffies;
4964 struct sched_domain *sd;
4966 if (unlikely(idle_cpu(cpu)))
4970 * We may be recently in ticked or tickless idle mode. At the first
4971 * busy tick after returning from idle, we will update the busy stats.
4973 set_cpu_sd_state_busy();
4974 nohz_balance_exit_idle(cpu);
4977 * None are in tickless mode and hence no need for NOHZ idle load
4980 if (likely(!atomic_read(&nohz.nr_cpus)))
4983 if (time_before(now, nohz.next_balance))
4986 if (rq->nr_running >= 2)
4990 for_each_domain(cpu, sd) {
4991 struct sched_group *sg = sd->groups;
4992 struct sched_group_power *sgp = sg->sgp;
4993 int nr_busy = atomic_read(&sgp->nr_busy_cpus);
4995 if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
4996 goto need_kick_unlock;
4998 if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
4999 && (cpumask_first_and(nohz.idle_cpus_mask,
5000 sched_domain_span(sd)) < cpu))
5001 goto need_kick_unlock;
5003 if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
5015 static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { }
5019 * run_rebalance_domains is triggered when needed from the scheduler tick.
5020 * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
5022 static void run_rebalance_domains(struct softirq_action *h)
5024 int this_cpu = smp_processor_id();
5025 struct rq *this_rq = cpu_rq(this_cpu);
5026 enum cpu_idle_type idle = this_rq->idle_balance ?
5027 CPU_IDLE : CPU_NOT_IDLE;
5029 rebalance_domains(this_cpu, idle);
5032 * If this cpu has a pending nohz_balance_kick, then do the
5033 * balancing on behalf of the other idle cpus whose ticks are
5036 nohz_idle_balance(this_cpu, idle);
5039 static inline int on_null_domain(int cpu)
5041 return !rcu_dereference_sched(cpu_rq(cpu)->sd);
5045 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
5047 void trigger_load_balance(struct rq *rq, int cpu)
5049 /* Don't need to rebalance while attached to NULL domain */
5050 if (time_after_eq(jiffies, rq->next_balance) &&
5051 likely(!on_null_domain(cpu)))
5052 raise_softirq(SCHED_SOFTIRQ);
5054 if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu)))
5055 nohz_balancer_kick(cpu);
5059 static void rq_online_fair(struct rq *rq)
5064 static void rq_offline_fair(struct rq *rq)
5068 /* Ensure any throttled groups are reachable by pick_next_task */
5069 unthrottle_offline_cfs_rqs(rq);
5072 #endif /* CONFIG_SMP */
5075 * scheduler tick hitting a task of our scheduling class:
5077 static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
5079 struct cfs_rq *cfs_rq;
5080 struct sched_entity *se = &curr->se;
5082 for_each_sched_entity(se) {
5083 cfs_rq = cfs_rq_of(se);
5084 entity_tick(cfs_rq, se, queued);
5089 * called on fork with the child task as argument from the parent's context
5090 * - child not yet on the tasklist
5091 * - preemption disabled
5093 static void task_fork_fair(struct task_struct *p)
5095 struct cfs_rq *cfs_rq;
5096 struct sched_entity *se = &p->se, *curr;
5097 int this_cpu = smp_processor_id();
5098 struct rq *rq = this_rq();
5099 unsigned long flags;
5101 raw_spin_lock_irqsave(&rq->lock, flags);
5103 update_rq_clock(rq);
5105 cfs_rq = task_cfs_rq(current);
5106 curr = cfs_rq->curr;
5108 if (unlikely(task_cpu(p) != this_cpu)) {
5110 __set_task_cpu(p, this_cpu);
5114 update_curr(cfs_rq);
5117 se->vruntime = curr->vruntime;
5118 place_entity(cfs_rq, se, 1);
5120 if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
5122 * Upon rescheduling, sched_class::put_prev_task() will place
5123 * 'current' within the tree based on its new key value.
5125 swap(curr->vruntime, se->vruntime);
5126 resched_task(rq->curr);
5129 se->vruntime -= cfs_rq->min_vruntime;
5131 raw_spin_unlock_irqrestore(&rq->lock, flags);
5135 * Priority of the task has changed. Check to see if we preempt
5139 prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
5145 * Reschedule if we are currently running on this runqueue and
5146 * our priority decreased, or if we are not currently running on
5147 * this runqueue and our priority is higher than the current's
5149 if (rq->curr == p) {
5150 if (p->prio > oldprio)
5151 resched_task(rq->curr);
5153 check_preempt_curr(rq, p, 0);
5156 static void switched_from_fair(struct rq *rq, struct task_struct *p)
5158 struct sched_entity *se = &p->se;
5159 struct cfs_rq *cfs_rq = cfs_rq_of(se);
5162 * Ensure the task's vruntime is normalized, so that when its
5163 * switched back to the fair class the enqueue_entity(.flags=0) will
5164 * do the right thing.
5166 * If it was on_rq, then the dequeue_entity(.flags=0) will already
5167 * have normalized the vruntime, if it was !on_rq, then only when
5168 * the task is sleeping will it still have non-normalized vruntime.
5170 if (!se->on_rq && p->state != TASK_RUNNING) {
5172 * Fix up our vruntime so that the current sleep doesn't
5173 * cause 'unlimited' sleep bonus.
5175 place_entity(cfs_rq, se, 0);
5176 se->vruntime -= cfs_rq->min_vruntime;
5181 * We switched to the sched_fair class.
5183 static void switched_to_fair(struct rq *rq, struct task_struct *p)
5189 * We were most likely switched from sched_rt, so
5190 * kick off the schedule if running, otherwise just see
5191 * if we can still preempt the current task.
5194 resched_task(rq->curr);
5196 check_preempt_curr(rq, p, 0);
5199 /* Account for a task changing its policy or group.
5201 * This routine is mostly called to set cfs_rq->curr field when a task
5202 * migrates between groups/classes.
5204 static void set_curr_task_fair(struct rq *rq)
5206 struct sched_entity *se = &rq->curr->se;
5208 for_each_sched_entity(se) {
5209 struct cfs_rq *cfs_rq = cfs_rq_of(se);
5211 set_next_entity(cfs_rq, se);
5212 /* ensure bandwidth has been allocated on our new cfs_rq */
5213 account_cfs_rq_runtime(cfs_rq, 0);
5217 void init_cfs_rq(struct cfs_rq *cfs_rq)
5219 cfs_rq->tasks_timeline = RB_ROOT;
5220 cfs_rq->min_vruntime = (u64)(-(1LL << 20));
5221 #ifndef CONFIG_64BIT
5222 cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
5226 #ifdef CONFIG_FAIR_GROUP_SCHED
5227 static void task_move_group_fair(struct task_struct *p, int on_rq)
5230 * If the task was not on the rq at the time of this cgroup movement
5231 * it must have been asleep, sleeping tasks keep their ->vruntime
5232 * absolute on their old rq until wakeup (needed for the fair sleeper
5233 * bonus in place_entity()).
5235 * If it was on the rq, we've just 'preempted' it, which does convert
5236 * ->vruntime to a relative base.
5238 * Make sure both cases convert their relative position when migrating
5239 * to another cgroup's rq. This does somewhat interfere with the
5240 * fair sleeper stuff for the first placement, but who cares.
5243 * When !on_rq, vruntime of the task has usually NOT been normalized.
5244 * But there are some cases where it has already been normalized:
5246 * - Moving a forked child which is waiting for being woken up by
5247 * wake_up_new_task().
5248 * - Moving a task which has been woken up by try_to_wake_up() and
5249 * waiting for actually being woken up by sched_ttwu_pending().
5251 * To prevent boost or penalty in the new cfs_rq caused by delta
5252 * min_vruntime between the two cfs_rqs, we skip vruntime adjustment.
5254 if (!on_rq && (!p->se.sum_exec_runtime || p->state == TASK_WAKING))
5258 p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime;
5259 set_task_rq(p, task_cpu(p));
5261 p->se.vruntime += cfs_rq_of(&p->se)->min_vruntime;
5264 void free_fair_sched_group(struct task_group *tg)
5268 destroy_cfs_bandwidth(tg_cfs_bandwidth(tg));
5270 for_each_possible_cpu(i) {
5272 kfree(tg->cfs_rq[i]);
5281 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
5283 struct cfs_rq *cfs_rq;
5284 struct sched_entity *se;
5287 tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL);
5290 tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL);
5294 tg->shares = NICE_0_LOAD;
5296 init_cfs_bandwidth(tg_cfs_bandwidth(tg));
5298 for_each_possible_cpu(i) {
5299 cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
5300 GFP_KERNEL, cpu_to_node(i));
5304 se = kzalloc_node(sizeof(struct sched_entity),
5305 GFP_KERNEL, cpu_to_node(i));
5309 init_cfs_rq(cfs_rq);
5310 init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);
5321 void unregister_fair_sched_group(struct task_group *tg, int cpu)
5323 struct rq *rq = cpu_rq(cpu);
5324 unsigned long flags;
5327 * Only empty task groups can be destroyed; so we can speculatively
5328 * check on_list without danger of it being re-added.
5330 if (!tg->cfs_rq[cpu]->on_list)
5333 raw_spin_lock_irqsave(&rq->lock, flags);
5334 list_del_leaf_cfs_rq(tg->cfs_rq[cpu]);
5335 raw_spin_unlock_irqrestore(&rq->lock, flags);
5338 void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
5339 struct sched_entity *se, int cpu,
5340 struct sched_entity *parent)
5342 struct rq *rq = cpu_rq(cpu);
5347 /* allow initial update_cfs_load() to truncate */
5348 cfs_rq->load_stamp = 1;
5350 init_cfs_rq_runtime(cfs_rq);
5352 tg->cfs_rq[cpu] = cfs_rq;
5355 /* se could be NULL for root_task_group */
5360 se->cfs_rq = &rq->cfs;
5362 se->cfs_rq = parent->my_q;
5365 update_load_set(&se->load, 0);
5366 se->parent = parent;
5369 static DEFINE_MUTEX(shares_mutex);
5371 int sched_group_set_shares(struct task_group *tg, unsigned long shares)
5374 unsigned long flags;
5377 * We can't change the weight of the root cgroup.
5382 shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES));
5384 mutex_lock(&shares_mutex);
5385 if (tg->shares == shares)
5388 tg->shares = shares;
5389 for_each_possible_cpu(i) {
5390 struct rq *rq = cpu_rq(i);
5391 struct sched_entity *se;
5394 /* Propagate contribution to hierarchy */
5395 raw_spin_lock_irqsave(&rq->lock, flags);
5396 for_each_sched_entity(se)
5397 update_cfs_shares(group_cfs_rq(se));
5398 raw_spin_unlock_irqrestore(&rq->lock, flags);
5402 mutex_unlock(&shares_mutex);
5405 #else /* CONFIG_FAIR_GROUP_SCHED */
5407 void free_fair_sched_group(struct task_group *tg) { }
5409 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
5414 void unregister_fair_sched_group(struct task_group *tg, int cpu) { }
5416 #endif /* CONFIG_FAIR_GROUP_SCHED */
5419 static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
5421 struct sched_entity *se = &task->se;
5422 unsigned int rr_interval = 0;
5425 * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
5428 if (rq->cfs.load.weight)
5429 rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
5435 * All the scheduling class methods:
5437 const struct sched_class fair_sched_class = {
5438 .next = &idle_sched_class,
5439 .enqueue_task = enqueue_task_fair,
5440 .dequeue_task = dequeue_task_fair,
5441 .yield_task = yield_task_fair,
5442 .yield_to_task = yield_to_task_fair,
5444 .check_preempt_curr = check_preempt_wakeup,
5446 .pick_next_task = pick_next_task_fair,
5447 .put_prev_task = put_prev_task_fair,
5450 .select_task_rq = select_task_rq_fair,
5452 .rq_online = rq_online_fair,
5453 .rq_offline = rq_offline_fair,
5455 .task_waking = task_waking_fair,
5458 .set_curr_task = set_curr_task_fair,
5459 .task_tick = task_tick_fair,
5460 .task_fork = task_fork_fair,
5462 .prio_changed = prio_changed_fair,
5463 .switched_from = switched_from_fair,
5464 .switched_to = switched_to_fair,
5466 .get_rr_interval = get_rr_interval_fair,
5468 #ifdef CONFIG_FAIR_GROUP_SCHED
5469 .task_move_group = task_move_group_fair,
5473 #ifdef CONFIG_SCHED_DEBUG
5474 void print_cfs_stats(struct seq_file *m, int cpu)
5476 struct cfs_rq *cfs_rq;
5479 for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
5480 print_cfs_rq(m, cpu, cfs_rq);
5485 __init void init_sched_fair_class(void)
5488 open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
5491 nohz.next_balance = jiffies;
5492 zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
5493 cpu_notifier(sched_ilb_notifier, 0);