2 * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH)
4 * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
6 * Interactivity improvements by Mike Galbraith
7 * (C) 2007 Mike Galbraith <efault@gmx.de>
9 * Various enhancements by Dmitry Adamushko.
10 * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com>
12 * Group scheduling enhancements by Srivatsa Vaddagiri
13 * Copyright IBM Corporation, 2007
14 * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
16 * Scaled math optimizations by Thomas Gleixner
17 * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de>
19 * Adaptive scheduling granularity, math enhancements by Peter Zijlstra
20 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
23 #include <linux/latencytop.h>
24 #include <linux/sched.h>
25 #include <linux/cpumask.h>
26 #include <linux/slab.h>
27 #include <linux/profile.h>
28 #include <linux/interrupt.h>
29 #include <linux/mempolicy.h>
30 #include <linux/migrate.h>
31 #include <linux/task_work.h>
33 #include <trace/events/sched.h>
34 #ifdef CONFIG_HMP_VARIABLE_SCALE
35 #include <linux/sysfs.h>
36 #include <linux/vmalloc.h>
37 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
38 /* Include cpufreq header to add a notifier so that cpu frequency
39 * scaling can track the current CPU frequency
41 #include <linux/cpufreq.h>
42 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
43 #endif /* CONFIG_HMP_VARIABLE_SCALE */
49 * Targeted preemption latency for CPU-bound tasks:
50 * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
52 * NOTE: this latency value is not the same as the concept of
53 * 'timeslice length' - timeslices in CFS are of variable length
54 * and have no persistent notion like in traditional, time-slice
55 * based scheduling concepts.
57 * (to see the precise effective timeslice length of your workload,
58 * run vmstat and monitor the context-switches (cs) field)
60 unsigned int sysctl_sched_latency = 6000000ULL;
61 unsigned int normalized_sysctl_sched_latency = 6000000ULL;
64 * The initial- and re-scaling of tunables is configurable
65 * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
68 * SCHED_TUNABLESCALING_NONE - unscaled, always *1
69 * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
70 * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
72 enum sched_tunable_scaling sysctl_sched_tunable_scaling
73 = SCHED_TUNABLESCALING_LOG;
76 * Minimal preemption granularity for CPU-bound tasks:
77 * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
79 unsigned int sysctl_sched_min_granularity = 750000ULL;
80 unsigned int normalized_sysctl_sched_min_granularity = 750000ULL;
83 * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
85 static unsigned int sched_nr_latency = 8;
88 * After fork, child runs first. If set to 0 (default) then
89 * parent will (try to) run first.
91 unsigned int sysctl_sched_child_runs_first __read_mostly;
94 * SCHED_OTHER wake-up granularity.
95 * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
97 * This option delays the preemption effects of decoupled workloads
98 * and reduces their over-scheduling. Synchronous workloads will still
99 * have immediate wakeup/sleep latencies.
101 unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
102 unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
104 const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
107 * The exponential sliding window over which load is averaged for shares
111 unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
113 #ifdef CONFIG_CFS_BANDWIDTH
115 * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
116 * each time a cfs_rq requests quota.
118 * Note: in the case that the slice exceeds the runtime remaining (either due
119 * to consumption or the quota being specified to be smaller than the slice)
120 * we will always only issue the remaining available time.
122 * default: 5 msec, units: microseconds
124 unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL;
128 * Increase the granularity value when there are more CPUs,
129 * because with more CPUs the 'effective latency' as visible
130 * to users decreases. But the relationship is not linear,
131 * so pick a second-best guess by going with the log2 of the
134 * This idea comes from the SD scheduler of Con Kolivas:
136 static int get_update_sysctl_factor(void)
138 unsigned int cpus = min_t(int, num_online_cpus(), 8);
141 switch (sysctl_sched_tunable_scaling) {
142 case SCHED_TUNABLESCALING_NONE:
145 case SCHED_TUNABLESCALING_LINEAR:
148 case SCHED_TUNABLESCALING_LOG:
150 factor = 1 + ilog2(cpus);
157 static void update_sysctl(void)
159 unsigned int factor = get_update_sysctl_factor();
161 #define SET_SYSCTL(name) \
162 (sysctl_##name = (factor) * normalized_sysctl_##name)
163 SET_SYSCTL(sched_min_granularity);
164 SET_SYSCTL(sched_latency);
165 SET_SYSCTL(sched_wakeup_granularity);
169 void sched_init_granularity(void)
174 #if BITS_PER_LONG == 32
175 # define WMULT_CONST (~0UL)
177 # define WMULT_CONST (1UL << 32)
180 #define WMULT_SHIFT 32
183 * Shift right and round:
185 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
188 * delta *= weight / lw
191 calc_delta_mine(unsigned long delta_exec, unsigned long weight,
192 struct load_weight *lw)
197 * weight can be less than 2^SCHED_LOAD_RESOLUTION for task group sched
198 * entities since MIN_SHARES = 2. Treat weight as 1 if less than
199 * 2^SCHED_LOAD_RESOLUTION.
201 if (likely(weight > (1UL << SCHED_LOAD_RESOLUTION)))
202 tmp = (u64)delta_exec * scale_load_down(weight);
204 tmp = (u64)delta_exec;
206 if (!lw->inv_weight) {
207 unsigned long w = scale_load_down(lw->weight);
209 if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST))
211 else if (unlikely(!w))
212 lw->inv_weight = WMULT_CONST;
214 lw->inv_weight = WMULT_CONST / w;
218 * Check whether we'd overflow the 64-bit multiplication:
220 if (unlikely(tmp > WMULT_CONST))
221 tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight,
224 tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT);
226 return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
230 const struct sched_class fair_sched_class;
232 /**************************************************************
233 * CFS operations on generic schedulable entities:
236 #ifdef CONFIG_FAIR_GROUP_SCHED
238 /* cpu runqueue to which this cfs_rq is attached */
239 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
244 /* An entity is a task if it doesn't "own" a runqueue */
245 #define entity_is_task(se) (!se->my_q)
247 static inline struct task_struct *task_of(struct sched_entity *se)
249 #ifdef CONFIG_SCHED_DEBUG
250 WARN_ON_ONCE(!entity_is_task(se));
252 return container_of(se, struct task_struct, se);
255 /* Walk up scheduling entities hierarchy */
256 #define for_each_sched_entity(se) \
257 for (; se; se = se->parent)
259 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
264 /* runqueue on which this entity is (to be) queued */
265 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
270 /* runqueue "owned" by this group */
271 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
276 static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
279 static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
281 if (!cfs_rq->on_list) {
283 * Ensure we either appear before our parent (if already
284 * enqueued) or force our parent to appear after us when it is
285 * enqueued. The fact that we always enqueue bottom-up
286 * reduces this to two cases.
288 if (cfs_rq->tg->parent &&
289 cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) {
290 list_add_rcu(&cfs_rq->leaf_cfs_rq_list,
291 &rq_of(cfs_rq)->leaf_cfs_rq_list);
293 list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
294 &rq_of(cfs_rq)->leaf_cfs_rq_list);
298 /* We should have no load, but we need to update last_decay. */
299 update_cfs_rq_blocked_load(cfs_rq, 0);
303 static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
305 if (cfs_rq->on_list) {
306 list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
311 /* Iterate thr' all leaf cfs_rq's on a runqueue */
312 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
313 list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
315 /* Do the two (enqueued) entities belong to the same group ? */
317 is_same_group(struct sched_entity *se, struct sched_entity *pse)
319 if (se->cfs_rq == pse->cfs_rq)
325 static inline struct sched_entity *parent_entity(struct sched_entity *se)
330 /* return depth at which a sched entity is present in the hierarchy */
331 static inline int depth_se(struct sched_entity *se)
335 for_each_sched_entity(se)
342 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
344 int se_depth, pse_depth;
347 * preemption test can be made between sibling entities who are in the
348 * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
349 * both tasks until we find their ancestors who are siblings of common
353 /* First walk up until both entities are at same depth */
354 se_depth = depth_se(*se);
355 pse_depth = depth_se(*pse);
357 while (se_depth > pse_depth) {
359 *se = parent_entity(*se);
362 while (pse_depth > se_depth) {
364 *pse = parent_entity(*pse);
367 while (!is_same_group(*se, *pse)) {
368 *se = parent_entity(*se);
369 *pse = parent_entity(*pse);
373 #else /* !CONFIG_FAIR_GROUP_SCHED */
375 static inline struct task_struct *task_of(struct sched_entity *se)
377 return container_of(se, struct task_struct, se);
380 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
382 return container_of(cfs_rq, struct rq, cfs);
385 #define entity_is_task(se) 1
387 #define for_each_sched_entity(se) \
388 for (; se; se = NULL)
390 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
392 return &task_rq(p)->cfs;
395 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
397 struct task_struct *p = task_of(se);
398 struct rq *rq = task_rq(p);
403 /* runqueue "owned" by this group */
404 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
409 static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
413 static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
417 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
418 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
421 is_same_group(struct sched_entity *se, struct sched_entity *pse)
426 static inline struct sched_entity *parent_entity(struct sched_entity *se)
432 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
436 #endif /* CONFIG_FAIR_GROUP_SCHED */
438 static __always_inline
439 void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec);
441 /**************************************************************
442 * Scheduling class tree data structure manipulation methods:
445 static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime)
447 s64 delta = (s64)(vruntime - max_vruntime);
449 max_vruntime = vruntime;
454 static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
456 s64 delta = (s64)(vruntime - min_vruntime);
458 min_vruntime = vruntime;
463 static inline int entity_before(struct sched_entity *a,
464 struct sched_entity *b)
466 return (s64)(a->vruntime - b->vruntime) < 0;
469 static void update_min_vruntime(struct cfs_rq *cfs_rq)
471 u64 vruntime = cfs_rq->min_vruntime;
474 vruntime = cfs_rq->curr->vruntime;
476 if (cfs_rq->rb_leftmost) {
477 struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost,
482 vruntime = se->vruntime;
484 vruntime = min_vruntime(vruntime, se->vruntime);
487 /* ensure we never gain time by being placed backwards. */
488 cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
491 cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
496 * Enqueue an entity into the rb-tree:
498 static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
500 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
501 struct rb_node *parent = NULL;
502 struct sched_entity *entry;
506 * Find the right place in the rbtree:
510 entry = rb_entry(parent, struct sched_entity, run_node);
512 * We dont care about collisions. Nodes with
513 * the same key stay together.
515 if (entity_before(se, entry)) {
516 link = &parent->rb_left;
518 link = &parent->rb_right;
524 * Maintain a cache of leftmost tree entries (it is frequently
528 cfs_rq->rb_leftmost = &se->run_node;
530 rb_link_node(&se->run_node, parent, link);
531 rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
534 static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
536 if (cfs_rq->rb_leftmost == &se->run_node) {
537 struct rb_node *next_node;
539 next_node = rb_next(&se->run_node);
540 cfs_rq->rb_leftmost = next_node;
543 rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
546 struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
548 struct rb_node *left = cfs_rq->rb_leftmost;
553 return rb_entry(left, struct sched_entity, run_node);
556 static struct sched_entity *__pick_next_entity(struct sched_entity *se)
558 struct rb_node *next = rb_next(&se->run_node);
563 return rb_entry(next, struct sched_entity, run_node);
566 #ifdef CONFIG_SCHED_DEBUG
567 struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
569 struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
574 return rb_entry(last, struct sched_entity, run_node);
577 /**************************************************************
578 * Scheduling class statistics methods:
581 int sched_proc_update_handler(struct ctl_table *table, int write,
582 void __user *buffer, size_t *lenp,
585 int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
586 int factor = get_update_sysctl_factor();
591 sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
592 sysctl_sched_min_granularity);
594 #define WRT_SYSCTL(name) \
595 (normalized_sysctl_##name = sysctl_##name / (factor))
596 WRT_SYSCTL(sched_min_granularity);
597 WRT_SYSCTL(sched_latency);
598 WRT_SYSCTL(sched_wakeup_granularity);
608 static inline unsigned long
609 calc_delta_fair(unsigned long delta, struct sched_entity *se)
611 if (unlikely(se->load.weight != NICE_0_LOAD))
612 delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load);
618 * The idea is to set a period in which each task runs once.
620 * When there are too many tasks (sched_nr_latency) we have to stretch
621 * this period because otherwise the slices get too small.
623 * p = (nr <= nl) ? l : l*nr/nl
625 static u64 __sched_period(unsigned long nr_running)
627 u64 period = sysctl_sched_latency;
628 unsigned long nr_latency = sched_nr_latency;
630 if (unlikely(nr_running > nr_latency)) {
631 period = sysctl_sched_min_granularity;
632 period *= nr_running;
639 * We calculate the wall-time slice from the period by taking a part
640 * proportional to the weight.
644 static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
646 u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq);
648 for_each_sched_entity(se) {
649 struct load_weight *load;
650 struct load_weight lw;
652 cfs_rq = cfs_rq_of(se);
653 load = &cfs_rq->load;
655 if (unlikely(!se->on_rq)) {
658 update_load_add(&lw, se->load.weight);
661 slice = calc_delta_mine(slice, se->load.weight, load);
667 * We calculate the vruntime slice of a to-be-inserted task.
671 static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
673 return calc_delta_fair(sched_slice(cfs_rq, se), se);
677 * Update the current task's runtime statistics. Skip current tasks that
678 * are not in our scheduling class.
681 __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
682 unsigned long delta_exec)
684 unsigned long delta_exec_weighted;
686 schedstat_set(curr->statistics.exec_max,
687 max((u64)delta_exec, curr->statistics.exec_max));
689 curr->sum_exec_runtime += delta_exec;
690 schedstat_add(cfs_rq, exec_clock, delta_exec);
691 delta_exec_weighted = calc_delta_fair(delta_exec, curr);
693 curr->vruntime += delta_exec_weighted;
694 update_min_vruntime(cfs_rq);
697 static void update_curr(struct cfs_rq *cfs_rq)
699 struct sched_entity *curr = cfs_rq->curr;
700 u64 now = rq_of(cfs_rq)->clock_task;
701 unsigned long delta_exec;
707 * Get the amount of time the current task was running
708 * since the last time we changed load (this cannot
709 * overflow on 32 bits):
711 delta_exec = (unsigned long)(now - curr->exec_start);
715 __update_curr(cfs_rq, curr, delta_exec);
716 curr->exec_start = now;
718 if (entity_is_task(curr)) {
719 struct task_struct *curtask = task_of(curr);
721 trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
722 cpuacct_charge(curtask, delta_exec);
723 account_group_exec_runtime(curtask, delta_exec);
726 account_cfs_rq_runtime(cfs_rq, delta_exec);
730 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
732 schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock);
736 * Task is being enqueued - update stats:
738 static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
741 * Are we enqueueing a waiting task? (for current tasks
742 * a dequeue/enqueue event is a NOP)
744 if (se != cfs_rq->curr)
745 update_stats_wait_start(cfs_rq, se);
749 update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
751 schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max,
752 rq_of(cfs_rq)->clock - se->statistics.wait_start));
753 schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1);
754 schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum +
755 rq_of(cfs_rq)->clock - se->statistics.wait_start);
756 #ifdef CONFIG_SCHEDSTATS
757 if (entity_is_task(se)) {
758 trace_sched_stat_wait(task_of(se),
759 rq_of(cfs_rq)->clock - se->statistics.wait_start);
762 schedstat_set(se->statistics.wait_start, 0);
766 update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
769 * Mark the end of the wait period if dequeueing a
772 if (se != cfs_rq->curr)
773 update_stats_wait_end(cfs_rq, se);
777 * We are picking a new current task - update its stats:
780 update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
783 * We are starting a new run period:
785 se->exec_start = rq_of(cfs_rq)->clock_task;
788 /**************************************************
789 * Scheduling class queueing methods:
792 #ifdef CONFIG_NUMA_BALANCING
794 * numa task sample period in ms
796 unsigned int sysctl_numa_balancing_scan_period_min = 100;
797 unsigned int sysctl_numa_balancing_scan_period_max = 100*50;
798 unsigned int sysctl_numa_balancing_scan_period_reset = 100*600;
800 /* Portion of address space to scan in MB */
801 unsigned int sysctl_numa_balancing_scan_size = 256;
803 /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */
804 unsigned int sysctl_numa_balancing_scan_delay = 1000;
806 static void task_numa_placement(struct task_struct *p)
810 if (!p->mm) /* for example, ksmd faulting in a user's mm */
812 seq = ACCESS_ONCE(p->mm->numa_scan_seq);
813 if (p->numa_scan_seq == seq)
815 p->numa_scan_seq = seq;
817 /* FIXME: Scheduling placement policy hints go here */
821 * Got a PROT_NONE fault for a page on @node.
823 void task_numa_fault(int node, int pages, bool migrated)
825 struct task_struct *p = current;
827 if (!sched_feat_numa(NUMA))
830 /* FIXME: Allocate task-specific structure for placement policy here */
833 * If pages are properly placed (did not migrate) then scan slower.
834 * This is reset periodically in case of phase changes
837 p->numa_scan_period = min(sysctl_numa_balancing_scan_period_max,
838 p->numa_scan_period + jiffies_to_msecs(10));
840 task_numa_placement(p);
843 static void reset_ptenuma_scan(struct task_struct *p)
845 ACCESS_ONCE(p->mm->numa_scan_seq)++;
846 p->mm->numa_scan_offset = 0;
850 * The expensive part of numa migration is done from task_work context.
851 * Triggered from task_tick_numa().
853 void task_numa_work(struct callback_head *work)
855 unsigned long migrate, next_scan, now = jiffies;
856 struct task_struct *p = current;
857 struct mm_struct *mm = p->mm;
858 struct vm_area_struct *vma;
859 unsigned long start, end;
862 WARN_ON_ONCE(p != container_of(work, struct task_struct, numa_work));
864 work->next = work; /* protect against double add */
866 * Who cares about NUMA placement when they're dying.
868 * NOTE: make sure not to dereference p->mm before this check,
869 * exit_task_work() happens _after_ exit_mm() so we could be called
870 * without p->mm even though we still had it when we enqueued this
873 if (p->flags & PF_EXITING)
877 * We do not care about task placement until a task runs on a node
878 * other than the first one used by the address space. This is
879 * largely because migrations are driven by what CPU the task
880 * is running on. If it's never scheduled on another node, it'll
881 * not migrate so why bother trapping the fault.
883 if (mm->first_nid == NUMA_PTE_SCAN_INIT)
884 mm->first_nid = numa_node_id();
885 if (mm->first_nid != NUMA_PTE_SCAN_ACTIVE) {
886 /* Are we running on a new node yet? */
887 if (numa_node_id() == mm->first_nid &&
888 !sched_feat_numa(NUMA_FORCE))
891 mm->first_nid = NUMA_PTE_SCAN_ACTIVE;
895 * Reset the scan period if enough time has gone by. Objective is that
896 * scanning will be reduced if pages are properly placed. As tasks
897 * can enter different phases this needs to be re-examined. Lacking
898 * proper tracking of reference behaviour, this blunt hammer is used.
900 migrate = mm->numa_next_reset;
901 if (time_after(now, migrate)) {
902 p->numa_scan_period = sysctl_numa_balancing_scan_period_min;
903 next_scan = now + msecs_to_jiffies(sysctl_numa_balancing_scan_period_reset);
904 xchg(&mm->numa_next_reset, next_scan);
908 * Enforce maximal scan/migration frequency..
910 migrate = mm->numa_next_scan;
911 if (time_before(now, migrate))
914 if (p->numa_scan_period == 0)
915 p->numa_scan_period = sysctl_numa_balancing_scan_period_min;
917 next_scan = now + msecs_to_jiffies(p->numa_scan_period);
918 if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate)
922 * Do not set pte_numa if the current running node is rate-limited.
923 * This loses statistics on the fault but if we are unwilling to
924 * migrate to this node, it is less likely we can do useful work
926 if (migrate_ratelimited(numa_node_id()))
929 start = mm->numa_scan_offset;
930 pages = sysctl_numa_balancing_scan_size;
931 pages <<= 20 - PAGE_SHIFT; /* MB in pages */
935 down_read(&mm->mmap_sem);
936 vma = find_vma(mm, start);
938 reset_ptenuma_scan(p);
942 for (; vma; vma = vma->vm_next) {
943 if (!vma_migratable(vma))
946 /* Skip small VMAs. They are not likely to be of relevance */
947 if (vma->vm_end - vma->vm_start < HPAGE_SIZE)
951 start = max(start, vma->vm_start);
952 end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE);
953 end = min(end, vma->vm_end);
954 pages -= change_prot_numa(vma, start, end);
959 } while (end != vma->vm_end);
964 * It is possible to reach the end of the VMA list but the last few VMAs are
965 * not guaranteed to the vma_migratable. If they are not, we would find the
966 * !migratable VMA on the next scan but not reset the scanner to the start
970 mm->numa_scan_offset = start;
972 reset_ptenuma_scan(p);
973 up_read(&mm->mmap_sem);
977 * Drive the periodic memory faults..
979 void task_tick_numa(struct rq *rq, struct task_struct *curr)
981 struct callback_head *work = &curr->numa_work;
985 * We don't care about NUMA placement if we don't have memory.
987 if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work)
991 * Using runtime rather than walltime has the dual advantage that
992 * we (mostly) drive the selection from busy threads and that the
993 * task needs to have done some actual work before we bother with
996 now = curr->se.sum_exec_runtime;
997 period = (u64)curr->numa_scan_period * NSEC_PER_MSEC;
999 if (now - curr->node_stamp > period) {
1000 if (!curr->node_stamp)
1001 curr->numa_scan_period = sysctl_numa_balancing_scan_period_min;
1002 curr->node_stamp = now;
1004 if (!time_before(jiffies, curr->mm->numa_next_scan)) {
1005 init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */
1006 task_work_add(curr, work, true);
1011 static void task_tick_numa(struct rq *rq, struct task_struct *curr)
1014 #endif /* CONFIG_NUMA_BALANCING */
1017 account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
1019 update_load_add(&cfs_rq->load, se->load.weight);
1020 if (!parent_entity(se))
1021 update_load_add(&rq_of(cfs_rq)->load, se->load.weight);
1023 if (entity_is_task(se))
1024 list_add(&se->group_node, &rq_of(cfs_rq)->cfs_tasks);
1026 cfs_rq->nr_running++;
1030 account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
1032 update_load_sub(&cfs_rq->load, se->load.weight);
1033 if (!parent_entity(se))
1034 update_load_sub(&rq_of(cfs_rq)->load, se->load.weight);
1035 if (entity_is_task(se))
1036 list_del_init(&se->group_node);
1037 cfs_rq->nr_running--;
1040 #ifdef CONFIG_FAIR_GROUP_SCHED
1042 static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq)
1047 * Use this CPU's actual weight instead of the last load_contribution
1048 * to gain a more accurate current total weight. See
1049 * update_cfs_rq_load_contribution().
1051 tg_weight = atomic64_read(&tg->load_avg);
1052 tg_weight -= cfs_rq->tg_load_contrib;
1053 tg_weight += cfs_rq->load.weight;
1058 static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
1060 long tg_weight, load, shares;
1062 tg_weight = calc_tg_weight(tg, cfs_rq);
1063 load = cfs_rq->load.weight;
1065 shares = (tg->shares * load);
1067 shares /= tg_weight;
1069 if (shares < MIN_SHARES)
1070 shares = MIN_SHARES;
1071 if (shares > tg->shares)
1072 shares = tg->shares;
1076 # else /* CONFIG_SMP */
1077 static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
1081 # endif /* CONFIG_SMP */
1082 static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
1083 unsigned long weight)
1086 /* commit outstanding execution time */
1087 if (cfs_rq->curr == se)
1088 update_curr(cfs_rq);
1089 account_entity_dequeue(cfs_rq, se);
1092 update_load_set(&se->load, weight);
1095 account_entity_enqueue(cfs_rq, se);
1098 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
1100 static void update_cfs_shares(struct cfs_rq *cfs_rq)
1102 struct task_group *tg;
1103 struct sched_entity *se;
1107 se = tg->se[cpu_of(rq_of(cfs_rq))];
1108 if (!se || throttled_hierarchy(cfs_rq))
1111 if (likely(se->load.weight == tg->shares))
1114 shares = calc_cfs_shares(cfs_rq, tg);
1116 reweight_entity(cfs_rq_of(se), se, shares);
1118 #else /* CONFIG_FAIR_GROUP_SCHED */
1119 static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
1122 #endif /* CONFIG_FAIR_GROUP_SCHED */
1124 /* Only depends on SMP, FAIR_GROUP_SCHED may be removed when useful in lb */
1125 #if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
1127 * We choose a half-life close to 1 scheduling period.
1128 * Note: The tables below are dependent on this value.
1130 #define LOAD_AVG_PERIOD 32
1131 #define LOAD_AVG_MAX 47742 /* maximum possible load avg */
1132 #define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_MAX_AVG */
1134 /* Precomputed fixed inverse multiplies for multiplication by y^n */
1135 static const u32 runnable_avg_yN_inv[] = {
1136 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6,
1137 0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85,
1138 0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581,
1139 0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9,
1140 0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80,
1141 0x85aac367, 0x82cd8698,
1145 * Precomputed \Sum y^k { 1<=k<=n }. These are floor(true_value) to prevent
1146 * over-estimates when re-combining.
1148 static const u32 runnable_avg_yN_sum[] = {
1149 0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103,
1150 9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082,
1151 17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371,
1156 * val * y^n, where y^32 ~= 0.5 (~1 scheduling period)
1158 static __always_inline u64 decay_load(u64 val, u64 n)
1160 unsigned int local_n;
1164 else if (unlikely(n > LOAD_AVG_PERIOD * 63))
1167 /* after bounds checking we can collapse to 32-bit */
1171 * As y^PERIOD = 1/2, we can combine
1172 * y^n = 1/2^(n/PERIOD) * k^(n%PERIOD)
1173 * With a look-up table which covers k^n (n<PERIOD)
1175 * To achieve constant time decay_load.
1177 if (unlikely(local_n >= LOAD_AVG_PERIOD)) {
1178 val >>= local_n / LOAD_AVG_PERIOD;
1179 local_n %= LOAD_AVG_PERIOD;
1182 val *= runnable_avg_yN_inv[local_n];
1183 /* We don't use SRR here since we always want to round down. */
1188 * For updates fully spanning n periods, the contribution to runnable
1189 * average will be: \Sum 1024*y^n
1191 * We can compute this reasonably efficiently by combining:
1192 * y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for n <PERIOD}
1194 static u32 __compute_runnable_contrib(u64 n)
1198 if (likely(n <= LOAD_AVG_PERIOD))
1199 return runnable_avg_yN_sum[n];
1200 else if (unlikely(n >= LOAD_AVG_MAX_N))
1201 return LOAD_AVG_MAX;
1203 /* Compute \Sum k^n combining precomputed values for k^i, \Sum k^j */
1205 contrib /= 2; /* y^LOAD_AVG_PERIOD = 1/2 */
1206 contrib += runnable_avg_yN_sum[LOAD_AVG_PERIOD];
1208 n -= LOAD_AVG_PERIOD;
1209 } while (n > LOAD_AVG_PERIOD);
1211 contrib = decay_load(contrib, n);
1212 return contrib + runnable_avg_yN_sum[n];
1215 #ifdef CONFIG_HMP_VARIABLE_SCALE
1217 #define HMP_VARIABLE_SCALE_SHIFT 16ULL
1218 struct hmp_global_attr {
1219 struct attribute attr;
1220 ssize_t (*show)(struct kobject *kobj,
1221 struct attribute *attr, char *buf);
1222 ssize_t (*store)(struct kobject *a, struct attribute *b,
1223 const char *c, size_t count);
1225 int (*to_sysfs)(int);
1226 int (*from_sysfs)(int);
1229 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1230 #define HMP_DATA_SYSFS_MAX 4
1232 #define HMP_DATA_SYSFS_MAX 3
1235 struct hmp_data_struct {
1236 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1237 int freqinvar_load_scale_enabled;
1239 int multiplier; /* used to scale the time delta */
1240 struct attribute_group attr_group;
1241 struct attribute *attributes[HMP_DATA_SYSFS_MAX + 1];
1242 struct hmp_global_attr attr[HMP_DATA_SYSFS_MAX];
1245 static u64 hmp_variable_scale_convert(u64 delta);
1246 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1247 /* Frequency-Invariant Load Modification:
1248 * Loads are calculated as in PJT's patch however we also scale the current
1249 * contribution in line with the frequency of the CPU that the task was
1251 * In this version, we use a simple linear scale derived from the maximum
1252 * frequency reported by CPUFreq. As an example:
1254 * Consider that we ran a task for 100% of the previous interval.
1256 * Our CPU was under asynchronous frequency control through one of the
1257 * CPUFreq governors.
1259 * The CPUFreq governor reports that it is able to scale the CPU between
1262 * During the period, the CPU was running at 1GHz.
1264 * In this case, our load contribution for that period is calculated as
1265 * 1 * (number_of_active_microseconds)
1267 * This results in our task being able to accumulate maximum load as normal.
1270 * Consider now that our CPU was executing at 500MHz.
1272 * We now scale the load contribution such that it is calculated as
1273 * 0.5 * (number_of_active_microseconds)
1275 * Our task can only record 50% maximum load during this period.
1277 * This represents the task consuming 50% of the CPU's *possible* compute
1278 * capacity. However the task did consume 100% of the CPU's *available*
1279 * compute capacity which is the value seen by the CPUFreq governor and
1280 * user-side CPU Utilization tools.
1282 * Restricting tracked load to be scaled by the CPU's frequency accurately
1283 * represents the consumption of possible compute capacity and allows the
1284 * HMP migration's simple threshold migration strategy to interact more
1285 * predictably with CPUFreq's asynchronous compute capacity changes.
1287 #define SCHED_FREQSCALE_SHIFT 10
1288 struct cpufreq_extents {
1294 /* Flag set when the governor in use only allows one frequency.
1297 #define SCHED_LOAD_FREQINVAR_SINGLEFREQ 0x01
1299 static struct cpufreq_extents freq_scale[CONFIG_NR_CPUS];
1300 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1301 #endif /* CONFIG_HMP_VARIABLE_SCALE */
1303 /* We can represent the historical contribution to runnable average as the
1304 * coefficients of a geometric series. To do this we sub-divide our runnable
1305 * history into segments of approximately 1ms (1024us); label the segment that
1306 * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g.
1308 * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ...
1310 * (now) (~1ms ago) (~2ms ago)
1312 * Let u_i denote the fraction of p_i that the entity was runnable.
1314 * We then designate the fractions u_i as our co-efficients, yielding the
1315 * following representation of historical load:
1316 * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ...
1318 * We choose y based on the with of a reasonably scheduling period, fixing:
1321 * This means that the contribution to load ~32ms ago (u_32) will be weighted
1322 * approximately half as much as the contribution to load within the last ms
1325 * When a period "rolls over" and we have new u_0`, multiplying the previous
1326 * sum again by y is sufficient to update:
1327 * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... )
1328 * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
1330 static __always_inline int __update_entity_runnable_avg(u64 now,
1331 struct sched_avg *sa,
1337 u32 runnable_contrib;
1338 int delta_w, decayed = 0;
1339 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1341 u32 scaled_runnable_contrib;
1343 u32 curr_scale = 1024;
1344 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1346 delta = now - sa->last_runnable_update;
1347 #ifdef CONFIG_HMP_VARIABLE_SCALE
1348 delta = hmp_variable_scale_convert(delta);
1351 * This should only happen when time goes backwards, which it
1352 * unfortunately does during sched clock init when we swap over to TSC.
1354 if ((s64)delta < 0) {
1355 sa->last_runnable_update = now;
1360 * Use 1024ns as the unit of measurement since it's a reasonable
1361 * approximation of 1us and fast to compute.
1366 sa->last_runnable_update = now;
1368 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1369 /* retrieve scale factor for load */
1370 if (hmp_data.freqinvar_load_scale_enabled)
1371 curr_scale = freq_scale[cpu].curr_scale;
1372 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1374 /* delta_w is the amount already accumulated against our next period */
1375 delta_w = sa->runnable_avg_period % 1024;
1376 if (delta + delta_w >= 1024) {
1377 /* period roll-over */
1381 * Now that we know we're crossing a period boundary, figure
1382 * out how much from delta we need to complete the current
1383 * period and accrue it.
1385 delta_w = 1024 - delta_w;
1386 /* scale runnable time if necessary */
1387 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1388 scaled_delta_w = (delta_w * curr_scale)
1389 >> SCHED_FREQSCALE_SHIFT;
1391 sa->runnable_avg_sum += scaled_delta_w;
1393 sa->usage_avg_sum += scaled_delta_w;
1396 sa->runnable_avg_sum += delta_w;
1398 sa->usage_avg_sum += delta_w;
1399 #endif /* #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1400 sa->runnable_avg_period += delta_w;
1404 /* Figure out how many additional periods this update spans */
1405 periods = delta / 1024;
1407 /* decay the load we have accumulated so far */
1408 sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum,
1410 sa->runnable_avg_period = decay_load(sa->runnable_avg_period,
1412 sa->usage_avg_sum = decay_load(sa->usage_avg_sum, periods + 1);
1413 /* add the contribution from this period */
1414 /* Efficiently calculate \sum (1..n_period) 1024*y^i */
1415 runnable_contrib = __compute_runnable_contrib(periods);
1416 /* Apply load scaling if necessary.
1417 * Note that multiplying the whole series is same as
1418 * multiplying all terms
1420 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1421 scaled_runnable_contrib = (runnable_contrib * curr_scale)
1422 >> SCHED_FREQSCALE_SHIFT;
1424 sa->runnable_avg_sum += scaled_runnable_contrib;
1426 sa->usage_avg_sum += scaled_runnable_contrib;
1429 sa->runnable_avg_sum += runnable_contrib;
1431 sa->usage_avg_sum += runnable_contrib;
1432 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1433 sa->runnable_avg_period += runnable_contrib;
1436 /* Remainder of delta accrued against u_0` */
1437 /* scale if necessary */
1438 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1439 scaled_delta = ((delta * curr_scale) >> SCHED_FREQSCALE_SHIFT);
1441 sa->runnable_avg_sum += scaled_delta;
1443 sa->usage_avg_sum += scaled_delta;
1446 sa->runnable_avg_sum += delta;
1448 sa->usage_avg_sum += delta;
1449 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1450 sa->runnable_avg_period += delta;
1455 /* Synchronize an entity's decay with its parenting cfs_rq.*/
1456 static inline u64 __synchronize_entity_decay(struct sched_entity *se)
1458 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1459 u64 decays = atomic64_read(&cfs_rq->decay_counter);
1461 decays -= se->avg.decay_count;
1465 se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays);
1466 se->avg.decay_count = 0;
1471 #ifdef CONFIG_FAIR_GROUP_SCHED
1472 static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
1475 struct task_group *tg = cfs_rq->tg;
1478 tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg;
1479 tg_contrib -= cfs_rq->tg_load_contrib;
1481 if (force_update || abs64(tg_contrib) > cfs_rq->tg_load_contrib / 8) {
1482 atomic64_add(tg_contrib, &tg->load_avg);
1483 cfs_rq->tg_load_contrib += tg_contrib;
1488 * Aggregate cfs_rq runnable averages into an equivalent task_group
1489 * representation for computing load contributions.
1491 static inline void __update_tg_runnable_avg(struct sched_avg *sa,
1492 struct cfs_rq *cfs_rq)
1494 struct task_group *tg = cfs_rq->tg;
1495 long contrib, usage_contrib;
1497 /* The fraction of a cpu used by this cfs_rq */
1498 contrib = div_u64(sa->runnable_avg_sum << NICE_0_SHIFT,
1499 sa->runnable_avg_period + 1);
1500 contrib -= cfs_rq->tg_runnable_contrib;
1502 usage_contrib = div_u64(sa->usage_avg_sum << NICE_0_SHIFT,
1503 sa->runnable_avg_period + 1);
1504 usage_contrib -= cfs_rq->tg_usage_contrib;
1507 * contrib/usage at this point represent deltas, only update if they
1510 if ((abs(contrib) > cfs_rq->tg_runnable_contrib / 64) ||
1511 (abs(usage_contrib) > cfs_rq->tg_usage_contrib / 64)) {
1512 atomic_add(contrib, &tg->runnable_avg);
1513 cfs_rq->tg_runnable_contrib += contrib;
1515 atomic_add(usage_contrib, &tg->usage_avg);
1516 cfs_rq->tg_usage_contrib += usage_contrib;
1520 static inline void __update_group_entity_contrib(struct sched_entity *se)
1522 struct cfs_rq *cfs_rq = group_cfs_rq(se);
1523 struct task_group *tg = cfs_rq->tg;
1528 contrib = cfs_rq->tg_load_contrib * tg->shares;
1529 se->avg.load_avg_contrib = div64_u64(contrib,
1530 atomic64_read(&tg->load_avg) + 1);
1533 * For group entities we need to compute a correction term in the case
1534 * that they are consuming <1 cpu so that we would contribute the same
1535 * load as a task of equal weight.
1537 * Explicitly co-ordinating this measurement would be expensive, but
1538 * fortunately the sum of each cpus contribution forms a usable
1539 * lower-bound on the true value.
1541 * Consider the aggregate of 2 contributions. Either they are disjoint
1542 * (and the sum represents true value) or they are disjoint and we are
1543 * understating by the aggregate of their overlap.
1545 * Extending this to N cpus, for a given overlap, the maximum amount we
1546 * understand is then n_i(n_i+1)/2 * w_i where n_i is the number of
1547 * cpus that overlap for this interval and w_i is the interval width.
1549 * On a small machine; the first term is well-bounded which bounds the
1550 * total error since w_i is a subset of the period. Whereas on a
1551 * larger machine, while this first term can be larger, if w_i is the
1552 * of consequential size guaranteed to see n_i*w_i quickly converge to
1553 * our upper bound of 1-cpu.
1555 runnable_avg = atomic_read(&tg->runnable_avg);
1556 if (runnable_avg < NICE_0_LOAD) {
1557 se->avg.load_avg_contrib *= runnable_avg;
1558 se->avg.load_avg_contrib >>= NICE_0_SHIFT;
1562 static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
1563 int force_update) {}
1564 static inline void __update_tg_runnable_avg(struct sched_avg *sa,
1565 struct cfs_rq *cfs_rq) {}
1566 static inline void __update_group_entity_contrib(struct sched_entity *se) {}
1569 static inline void __update_task_entity_contrib(struct sched_entity *se)
1573 /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
1574 contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);
1575 contrib /= (se->avg.runnable_avg_period + 1);
1576 se->avg.load_avg_contrib = scale_load(contrib);
1577 trace_sched_task_load_contrib(task_of(se), se->avg.load_avg_contrib);
1578 contrib = se->avg.runnable_avg_sum * scale_load_down(NICE_0_LOAD);
1579 contrib /= (se->avg.runnable_avg_period + 1);
1580 se->avg.load_avg_ratio = scale_load(contrib);
1581 trace_sched_task_runnable_ratio(task_of(se), se->avg.load_avg_ratio);
1584 /* Compute the current contribution to load_avg by se, return any delta */
1585 static long __update_entity_load_avg_contrib(struct sched_entity *se, long *ratio)
1587 long old_contrib = se->avg.load_avg_contrib;
1588 long old_ratio = se->avg.load_avg_ratio;
1590 if (entity_is_task(se)) {
1591 __update_task_entity_contrib(se);
1593 __update_tg_runnable_avg(&se->avg, group_cfs_rq(se));
1594 __update_group_entity_contrib(se);
1598 *ratio = se->avg.load_avg_ratio - old_ratio;
1599 return se->avg.load_avg_contrib - old_contrib;
1602 static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq,
1605 if (likely(load_contrib < cfs_rq->blocked_load_avg))
1606 cfs_rq->blocked_load_avg -= load_contrib;
1608 cfs_rq->blocked_load_avg = 0;
1611 static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq);
1613 /* Update a sched_entity's runnable average */
1614 static inline void update_entity_load_avg(struct sched_entity *se,
1617 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1618 long contrib_delta, ratio_delta;
1620 int cpu = -1; /* not used in normal case */
1622 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1623 cpu = cfs_rq->rq->cpu;
1626 * For a group entity we need to use their owned cfs_rq_clock_task() in
1627 * case they are the parent of a throttled hierarchy.
1629 if (entity_is_task(se))
1630 now = cfs_rq_clock_task(cfs_rq);
1632 now = cfs_rq_clock_task(group_cfs_rq(se));
1634 if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq,
1635 cfs_rq->curr == se, cpu))
1638 contrib_delta = __update_entity_load_avg_contrib(se, &ratio_delta);
1644 cfs_rq->runnable_load_avg += contrib_delta;
1645 rq_of(cfs_rq)->avg.load_avg_ratio += ratio_delta;
1647 subtract_blocked_load_contrib(cfs_rq, -contrib_delta);
1652 * Decay the load contributed by all blocked children and account this so that
1653 * their contribution may appropriately discounted when they wake up.
1655 static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update)
1657 u64 now = cfs_rq_clock_task(cfs_rq) >> 20;
1660 decays = now - cfs_rq->last_decay;
1661 if (!decays && !force_update)
1664 if (atomic64_read(&cfs_rq->removed_load)) {
1665 u64 removed_load = atomic64_xchg(&cfs_rq->removed_load, 0);
1666 subtract_blocked_load_contrib(cfs_rq, removed_load);
1670 cfs_rq->blocked_load_avg = decay_load(cfs_rq->blocked_load_avg,
1672 atomic64_add(decays, &cfs_rq->decay_counter);
1673 cfs_rq->last_decay = now;
1676 __update_cfs_rq_tg_load_contrib(cfs_rq, force_update);
1679 static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
1681 int cpu = -1; /* not used in normal case */
1683 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1686 __update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable,
1688 __update_tg_runnable_avg(&rq->avg, &rq->cfs);
1689 trace_sched_rq_runnable_ratio(cpu_of(rq), rq->avg.load_avg_ratio);
1690 trace_sched_rq_runnable_load(cpu_of(rq), rq->cfs.runnable_load_avg);
1691 trace_sched_rq_nr_running(cpu_of(rq), rq->nr_running, rq->nr_iowait.counter);
1694 /* Add the load generated by se into cfs_rq's child load-average */
1695 static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
1696 struct sched_entity *se,
1700 * We track migrations using entity decay_count <= 0, on a wake-up
1701 * migration we use a negative decay count to track the remote decays
1702 * accumulated while sleeping.
1704 if (unlikely(se->avg.decay_count <= 0)) {
1705 se->avg.last_runnable_update = rq_of(cfs_rq)->clock_task;
1706 if (se->avg.decay_count) {
1708 * In a wake-up migration we have to approximate the
1709 * time sleeping. This is because we can't synchronize
1710 * clock_task between the two cpus, and it is not
1711 * guaranteed to be read-safe. Instead, we can
1712 * approximate this using our carried decays, which are
1713 * explicitly atomically readable.
1715 se->avg.last_runnable_update -= (-se->avg.decay_count)
1717 update_entity_load_avg(se, 0);
1718 /* Indicate that we're now synchronized and on-rq */
1719 se->avg.decay_count = 0;
1723 __synchronize_entity_decay(se);
1726 /* migrated tasks did not contribute to our blocked load */
1728 subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib);
1729 update_entity_load_avg(se, 0);
1732 cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
1733 rq_of(cfs_rq)->avg.load_avg_ratio += se->avg.load_avg_ratio;
1735 /* we force update consideration on load-balancer moves */
1736 update_cfs_rq_blocked_load(cfs_rq, !wakeup);
1740 * Remove se's load from this cfs_rq child load-average, if the entity is
1741 * transitioning to a blocked state we track its projected decay using
1744 static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
1745 struct sched_entity *se,
1748 update_entity_load_avg(se, 1);
1749 /* we force update consideration on load-balancer moves */
1750 update_cfs_rq_blocked_load(cfs_rq, !sleep);
1752 cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib;
1753 rq_of(cfs_rq)->avg.load_avg_ratio -= se->avg.load_avg_ratio;
1756 cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
1757 se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
1758 } /* migrations, e.g. sleep=0 leave decay_count == 0 */
1762 * Update the rq's load with the elapsed running time before entering
1763 * idle. if the last scheduled task is not a CFS task, idle_enter will
1764 * be the only way to update the runnable statistic.
1766 void idle_enter_fair(struct rq *this_rq)
1768 update_rq_runnable_avg(this_rq, 1);
1772 * Update the rq's load with the elapsed idle time before a task is
1773 * scheduled. if the newly scheduled task is not a CFS task, idle_exit will
1774 * be the only way to update the runnable statistic.
1776 void idle_exit_fair(struct rq *this_rq)
1778 update_rq_runnable_avg(this_rq, 0);
1782 static inline void update_entity_load_avg(struct sched_entity *se,
1783 int update_cfs_rq) {}
1784 static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
1785 static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
1786 struct sched_entity *se,
1788 static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
1789 struct sched_entity *se,
1791 static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
1792 int force_update) {}
1795 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
1797 #ifdef CONFIG_SCHEDSTATS
1798 struct task_struct *tsk = NULL;
1800 if (entity_is_task(se))
1803 if (se->statistics.sleep_start) {
1804 u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start;
1809 if (unlikely(delta > se->statistics.sleep_max))
1810 se->statistics.sleep_max = delta;
1812 se->statistics.sleep_start = 0;
1813 se->statistics.sum_sleep_runtime += delta;
1816 account_scheduler_latency(tsk, delta >> 10, 1);
1817 trace_sched_stat_sleep(tsk, delta);
1820 if (se->statistics.block_start) {
1821 u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start;
1826 if (unlikely(delta > se->statistics.block_max))
1827 se->statistics.block_max = delta;
1829 se->statistics.block_start = 0;
1830 se->statistics.sum_sleep_runtime += delta;
1833 if (tsk->in_iowait) {
1834 se->statistics.iowait_sum += delta;
1835 se->statistics.iowait_count++;
1836 trace_sched_stat_iowait(tsk, delta);
1839 trace_sched_stat_blocked(tsk, delta);
1842 * Blocking time is in units of nanosecs, so shift by
1843 * 20 to get a milliseconds-range estimation of the
1844 * amount of time that the task spent sleeping:
1846 if (unlikely(prof_on == SLEEP_PROFILING)) {
1847 profile_hits(SLEEP_PROFILING,
1848 (void *)get_wchan(tsk),
1851 account_scheduler_latency(tsk, delta >> 10, 0);
1857 static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
1859 #ifdef CONFIG_SCHED_DEBUG
1860 s64 d = se->vruntime - cfs_rq->min_vruntime;
1865 if (d > 3*sysctl_sched_latency)
1866 schedstat_inc(cfs_rq, nr_spread_over);
1871 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
1873 u64 vruntime = cfs_rq->min_vruntime;
1876 * The 'current' period is already promised to the current tasks,
1877 * however the extra weight of the new task will slow them down a
1878 * little, place the new task so that it fits in the slot that
1879 * stays open at the end.
1881 if (initial && sched_feat(START_DEBIT))
1882 vruntime += sched_vslice(cfs_rq, se);
1884 /* sleeps up to a single latency don't count. */
1886 unsigned long thresh = sysctl_sched_latency;
1889 * Halve their sleep time's effect, to allow
1890 * for a gentler effect of sleepers:
1892 if (sched_feat(GENTLE_FAIR_SLEEPERS))
1898 /* ensure we never gain time by being placed backwards. */
1899 se->vruntime = max_vruntime(se->vruntime, vruntime);
1902 static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
1905 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1908 * Update the normalized vruntime before updating min_vruntime
1909 * through callig update_curr().
1911 if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING))
1912 se->vruntime += cfs_rq->min_vruntime;
1915 * Update run-time statistics of the 'current'.
1917 update_curr(cfs_rq);
1918 enqueue_entity_load_avg(cfs_rq, se, flags & ENQUEUE_WAKEUP);
1919 account_entity_enqueue(cfs_rq, se);
1920 update_cfs_shares(cfs_rq);
1922 if (flags & ENQUEUE_WAKEUP) {
1923 place_entity(cfs_rq, se, 0);
1924 enqueue_sleeper(cfs_rq, se);
1927 update_stats_enqueue(cfs_rq, se);
1928 check_spread(cfs_rq, se);
1929 if (se != cfs_rq->curr)
1930 __enqueue_entity(cfs_rq, se);
1933 if (cfs_rq->nr_running == 1) {
1934 list_add_leaf_cfs_rq(cfs_rq);
1935 check_enqueue_throttle(cfs_rq);
1939 static void __clear_buddies_last(struct sched_entity *se)
1941 for_each_sched_entity(se) {
1942 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1943 if (cfs_rq->last == se)
1944 cfs_rq->last = NULL;
1950 static void __clear_buddies_next(struct sched_entity *se)
1952 for_each_sched_entity(se) {
1953 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1954 if (cfs_rq->next == se)
1955 cfs_rq->next = NULL;
1961 static void __clear_buddies_skip(struct sched_entity *se)
1963 for_each_sched_entity(se) {
1964 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1965 if (cfs_rq->skip == se)
1966 cfs_rq->skip = NULL;
1972 static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
1974 if (cfs_rq->last == se)
1975 __clear_buddies_last(se);
1977 if (cfs_rq->next == se)
1978 __clear_buddies_next(se);
1980 if (cfs_rq->skip == se)
1981 __clear_buddies_skip(se);
1984 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
1987 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1990 * Update run-time statistics of the 'current'.
1992 update_curr(cfs_rq);
1993 dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP);
1995 update_stats_dequeue(cfs_rq, se);
1996 if (flags & DEQUEUE_SLEEP) {
1997 #ifdef CONFIG_SCHEDSTATS
1998 if (entity_is_task(se)) {
1999 struct task_struct *tsk = task_of(se);
2001 if (tsk->state & TASK_INTERRUPTIBLE)
2002 se->statistics.sleep_start = rq_of(cfs_rq)->clock;
2003 if (tsk->state & TASK_UNINTERRUPTIBLE)
2004 se->statistics.block_start = rq_of(cfs_rq)->clock;
2009 clear_buddies(cfs_rq, se);
2011 if (se != cfs_rq->curr)
2012 __dequeue_entity(cfs_rq, se);
2014 account_entity_dequeue(cfs_rq, se);
2017 * Normalize the entity after updating the min_vruntime because the
2018 * update can refer to the ->curr item and we need to reflect this
2019 * movement in our normalized position.
2021 if (!(flags & DEQUEUE_SLEEP))
2022 se->vruntime -= cfs_rq->min_vruntime;
2024 /* return excess runtime on last dequeue */
2025 return_cfs_rq_runtime(cfs_rq);
2027 update_min_vruntime(cfs_rq);
2028 update_cfs_shares(cfs_rq);
2032 * Preempt the current task with a newly woken task if needed:
2035 check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
2037 unsigned long ideal_runtime, delta_exec;
2038 struct sched_entity *se;
2041 ideal_runtime = sched_slice(cfs_rq, curr);
2042 delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
2043 if (delta_exec > ideal_runtime) {
2044 resched_task(rq_of(cfs_rq)->curr);
2046 * The current task ran long enough, ensure it doesn't get
2047 * re-elected due to buddy favours.
2049 clear_buddies(cfs_rq, curr);
2054 * Ensure that a task that missed wakeup preemption by a
2055 * narrow margin doesn't have to wait for a full slice.
2056 * This also mitigates buddy induced latencies under load.
2058 if (delta_exec < sysctl_sched_min_granularity)
2061 se = __pick_first_entity(cfs_rq);
2062 delta = curr->vruntime - se->vruntime;
2067 if (delta > ideal_runtime)
2068 resched_task(rq_of(cfs_rq)->curr);
2072 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
2074 /* 'current' is not kept within the tree. */
2077 * Any task has to be enqueued before it get to execute on
2078 * a CPU. So account for the time it spent waiting on the
2081 update_stats_wait_end(cfs_rq, se);
2082 __dequeue_entity(cfs_rq, se);
2083 update_entity_load_avg(se, 1);
2086 update_stats_curr_start(cfs_rq, se);
2088 #ifdef CONFIG_SCHEDSTATS
2090 * Track our maximum slice length, if the CPU's load is at
2091 * least twice that of our own weight (i.e. dont track it
2092 * when there are only lesser-weight tasks around):
2094 if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
2095 se->statistics.slice_max = max(se->statistics.slice_max,
2096 se->sum_exec_runtime - se->prev_sum_exec_runtime);
2099 se->prev_sum_exec_runtime = se->sum_exec_runtime;
2103 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
2106 * Pick the next process, keeping these things in mind, in this order:
2107 * 1) keep things fair between processes/task groups
2108 * 2) pick the "next" process, since someone really wants that to run
2109 * 3) pick the "last" process, for cache locality
2110 * 4) do not run the "skip" process, if something else is available
2112 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
2114 struct sched_entity *se = __pick_first_entity(cfs_rq);
2115 struct sched_entity *left = se;
2118 * Avoid running the skip buddy, if running something else can
2119 * be done without getting too unfair.
2121 if (cfs_rq->skip == se) {
2122 struct sched_entity *second = __pick_next_entity(se);
2123 if (second && wakeup_preempt_entity(second, left) < 1)
2128 * Prefer last buddy, try to return the CPU to a preempted task.
2130 if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
2134 * Someone really wants this to run. If it's not unfair, run it.
2136 if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
2139 clear_buddies(cfs_rq, se);
2144 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
2146 static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
2149 * If still on the runqueue then deactivate_task()
2150 * was not called and update_curr() has to be done:
2153 update_curr(cfs_rq);
2155 /* throttle cfs_rqs exceeding runtime */
2156 check_cfs_rq_runtime(cfs_rq);
2158 check_spread(cfs_rq, prev);
2160 update_stats_wait_start(cfs_rq, prev);
2161 /* Put 'current' back into the tree. */
2162 __enqueue_entity(cfs_rq, prev);
2163 /* in !on_rq case, update occurred at dequeue */
2164 update_entity_load_avg(prev, 1);
2166 cfs_rq->curr = NULL;
2170 entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
2173 * Update run-time statistics of the 'current'.
2175 update_curr(cfs_rq);
2178 * Ensure that runnable average is periodically updated.
2180 update_entity_load_avg(curr, 1);
2181 update_cfs_rq_blocked_load(cfs_rq, 1);
2183 #ifdef CONFIG_SCHED_HRTICK
2185 * queued ticks are scheduled to match the slice, so don't bother
2186 * validating it and just reschedule.
2189 resched_task(rq_of(cfs_rq)->curr);
2193 * don't let the period tick interfere with the hrtick preemption
2195 if (!sched_feat(DOUBLE_TICK) &&
2196 hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
2200 if (cfs_rq->nr_running > 1)
2201 check_preempt_tick(cfs_rq, curr);
2205 /**************************************************
2206 * CFS bandwidth control machinery
2209 #ifdef CONFIG_CFS_BANDWIDTH
2211 #ifdef HAVE_JUMP_LABEL
2212 static struct static_key __cfs_bandwidth_used;
2214 static inline bool cfs_bandwidth_used(void)
2216 return static_key_false(&__cfs_bandwidth_used);
2219 void account_cfs_bandwidth_used(int enabled, int was_enabled)
2221 /* only need to count groups transitioning between enabled/!enabled */
2222 if (enabled && !was_enabled)
2223 static_key_slow_inc(&__cfs_bandwidth_used);
2224 else if (!enabled && was_enabled)
2225 static_key_slow_dec(&__cfs_bandwidth_used);
2227 #else /* HAVE_JUMP_LABEL */
2228 static bool cfs_bandwidth_used(void)
2233 void account_cfs_bandwidth_used(int enabled, int was_enabled) {}
2234 #endif /* HAVE_JUMP_LABEL */
2237 * default period for cfs group bandwidth.
2238 * default: 0.1s, units: nanoseconds
2240 static inline u64 default_cfs_period(void)
2242 return 100000000ULL;
2245 static inline u64 sched_cfs_bandwidth_slice(void)
2247 return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
2251 * Replenish runtime according to assigned quota and update expiration time.
2252 * We use sched_clock_cpu directly instead of rq->clock to avoid adding
2253 * additional synchronization around rq->lock.
2255 * requires cfs_b->lock
2257 void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
2261 if (cfs_b->quota == RUNTIME_INF)
2264 now = sched_clock_cpu(smp_processor_id());
2265 cfs_b->runtime = cfs_b->quota;
2266 cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period);
2269 static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
2271 return &tg->cfs_bandwidth;
2274 /* rq->task_clock normalized against any time this cfs_rq has spent throttled */
2275 static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
2277 if (unlikely(cfs_rq->throttle_count))
2278 return cfs_rq->throttled_clock_task;
2280 return rq_of(cfs_rq)->clock_task - cfs_rq->throttled_clock_task_time;
2283 /* returns 0 on failure to allocate runtime */
2284 static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2286 struct task_group *tg = cfs_rq->tg;
2287 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
2288 u64 amount = 0, min_amount, expires;
2290 /* note: this is a positive sum as runtime_remaining <= 0 */
2291 min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining;
2293 raw_spin_lock(&cfs_b->lock);
2294 if (cfs_b->quota == RUNTIME_INF)
2295 amount = min_amount;
2298 * If the bandwidth pool has become inactive, then at least one
2299 * period must have elapsed since the last consumption.
2300 * Refresh the global state and ensure bandwidth timer becomes
2303 if (!cfs_b->timer_active) {
2304 __refill_cfs_bandwidth_runtime(cfs_b);
2305 __start_cfs_bandwidth(cfs_b);
2308 if (cfs_b->runtime > 0) {
2309 amount = min(cfs_b->runtime, min_amount);
2310 cfs_b->runtime -= amount;
2314 expires = cfs_b->runtime_expires;
2315 raw_spin_unlock(&cfs_b->lock);
2317 cfs_rq->runtime_remaining += amount;
2319 * we may have advanced our local expiration to account for allowed
2320 * spread between our sched_clock and the one on which runtime was
2323 if ((s64)(expires - cfs_rq->runtime_expires) > 0)
2324 cfs_rq->runtime_expires = expires;
2326 return cfs_rq->runtime_remaining > 0;
2330 * Note: This depends on the synchronization provided by sched_clock and the
2331 * fact that rq->clock snapshots this value.
2333 static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2335 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2336 struct rq *rq = rq_of(cfs_rq);
2338 /* if the deadline is ahead of our clock, nothing to do */
2339 if (likely((s64)(rq->clock - cfs_rq->runtime_expires) < 0))
2342 if (cfs_rq->runtime_remaining < 0)
2346 * If the local deadline has passed we have to consider the
2347 * possibility that our sched_clock is 'fast' and the global deadline
2348 * has not truly expired.
2350 * Fortunately we can check determine whether this the case by checking
2351 * whether the global deadline has advanced.
2354 if ((s64)(cfs_rq->runtime_expires - cfs_b->runtime_expires) >= 0) {
2355 /* extend local deadline, drift is bounded above by 2 ticks */
2356 cfs_rq->runtime_expires += TICK_NSEC;
2358 /* global deadline is ahead, expiration has passed */
2359 cfs_rq->runtime_remaining = 0;
2363 static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
2364 unsigned long delta_exec)
2366 /* dock delta_exec before expiring quota (as it could span periods) */
2367 cfs_rq->runtime_remaining -= delta_exec;
2368 expire_cfs_rq_runtime(cfs_rq);
2370 if (likely(cfs_rq->runtime_remaining > 0))
2374 * if we're unable to extend our runtime we resched so that the active
2375 * hierarchy can be throttled
2377 if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
2378 resched_task(rq_of(cfs_rq)->curr);
2381 static __always_inline
2382 void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec)
2384 if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
2387 __account_cfs_rq_runtime(cfs_rq, delta_exec);
2390 static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
2392 return cfs_bandwidth_used() && cfs_rq->throttled;
2395 /* check whether cfs_rq, or any parent, is throttled */
2396 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
2398 return cfs_bandwidth_used() && cfs_rq->throttle_count;
2402 * Ensure that neither of the group entities corresponding to src_cpu or
2403 * dest_cpu are members of a throttled hierarchy when performing group
2404 * load-balance operations.
2406 static inline int throttled_lb_pair(struct task_group *tg,
2407 int src_cpu, int dest_cpu)
2409 struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
2411 src_cfs_rq = tg->cfs_rq[src_cpu];
2412 dest_cfs_rq = tg->cfs_rq[dest_cpu];
2414 return throttled_hierarchy(src_cfs_rq) ||
2415 throttled_hierarchy(dest_cfs_rq);
2418 /* updated child weight may affect parent so we have to do this bottom up */
2419 static int tg_unthrottle_up(struct task_group *tg, void *data)
2421 struct rq *rq = data;
2422 struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
2424 cfs_rq->throttle_count--;
2426 if (!cfs_rq->throttle_count) {
2427 /* adjust cfs_rq_clock_task() */
2428 cfs_rq->throttled_clock_task_time += rq->clock_task -
2429 cfs_rq->throttled_clock_task;
2436 static int tg_throttle_down(struct task_group *tg, void *data)
2438 struct rq *rq = data;
2439 struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
2441 /* group is entering throttled state, stop time */
2442 if (!cfs_rq->throttle_count)
2443 cfs_rq->throttled_clock_task = rq->clock_task;
2444 cfs_rq->throttle_count++;
2449 static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
2451 struct rq *rq = rq_of(cfs_rq);
2452 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2453 struct sched_entity *se;
2454 long task_delta, dequeue = 1;
2456 se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
2458 /* freeze hierarchy runnable averages while throttled */
2460 walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
2463 task_delta = cfs_rq->h_nr_running;
2464 for_each_sched_entity(se) {
2465 struct cfs_rq *qcfs_rq = cfs_rq_of(se);
2466 /* throttled entity or throttle-on-deactivate */
2471 dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
2472 qcfs_rq->h_nr_running -= task_delta;
2474 if (qcfs_rq->load.weight)
2479 rq->nr_running -= task_delta;
2481 cfs_rq->throttled = 1;
2482 cfs_rq->throttled_clock = rq->clock;
2483 raw_spin_lock(&cfs_b->lock);
2484 list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
2485 raw_spin_unlock(&cfs_b->lock);
2488 void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
2490 struct rq *rq = rq_of(cfs_rq);
2491 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2492 struct sched_entity *se;
2496 se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
2498 cfs_rq->throttled = 0;
2499 raw_spin_lock(&cfs_b->lock);
2500 cfs_b->throttled_time += rq->clock - cfs_rq->throttled_clock;
2501 list_del_rcu(&cfs_rq->throttled_list);
2502 raw_spin_unlock(&cfs_b->lock);
2504 update_rq_clock(rq);
2505 /* update hierarchical throttle state */
2506 walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
2508 if (!cfs_rq->load.weight)
2511 task_delta = cfs_rq->h_nr_running;
2512 for_each_sched_entity(se) {
2516 cfs_rq = cfs_rq_of(se);
2518 enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);
2519 cfs_rq->h_nr_running += task_delta;
2521 if (cfs_rq_throttled(cfs_rq))
2526 rq->nr_running += task_delta;
2528 /* determine whether we need to wake up potentially idle cpu */
2529 if (rq->curr == rq->idle && rq->cfs.nr_running)
2530 resched_task(rq->curr);
2533 static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
2534 u64 remaining, u64 expires)
2536 struct cfs_rq *cfs_rq;
2537 u64 runtime = remaining;
2540 list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
2542 struct rq *rq = rq_of(cfs_rq);
2544 raw_spin_lock(&rq->lock);
2545 if (!cfs_rq_throttled(cfs_rq))
2548 runtime = -cfs_rq->runtime_remaining + 1;
2549 if (runtime > remaining)
2550 runtime = remaining;
2551 remaining -= runtime;
2553 cfs_rq->runtime_remaining += runtime;
2554 cfs_rq->runtime_expires = expires;
2556 /* we check whether we're throttled above */
2557 if (cfs_rq->runtime_remaining > 0)
2558 unthrottle_cfs_rq(cfs_rq);
2561 raw_spin_unlock(&rq->lock);
2572 * Responsible for refilling a task_group's bandwidth and unthrottling its
2573 * cfs_rqs as appropriate. If there has been no activity within the last
2574 * period the timer is deactivated until scheduling resumes; cfs_b->idle is
2575 * used to track this state.
2577 static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
2579 u64 runtime, runtime_expires;
2580 int idle = 1, throttled;
2582 raw_spin_lock(&cfs_b->lock);
2583 /* no need to continue the timer with no bandwidth constraint */
2584 if (cfs_b->quota == RUNTIME_INF)
2587 throttled = !list_empty(&cfs_b->throttled_cfs_rq);
2588 /* idle depends on !throttled (for the case of a large deficit) */
2589 idle = cfs_b->idle && !throttled;
2590 cfs_b->nr_periods += overrun;
2592 /* if we're going inactive then everything else can be deferred */
2596 __refill_cfs_bandwidth_runtime(cfs_b);
2599 /* mark as potentially idle for the upcoming period */
2604 /* account preceding periods in which throttling occurred */
2605 cfs_b->nr_throttled += overrun;
2608 * There are throttled entities so we must first use the new bandwidth
2609 * to unthrottle them before making it generally available. This
2610 * ensures that all existing debts will be paid before a new cfs_rq is
2613 runtime = cfs_b->runtime;
2614 runtime_expires = cfs_b->runtime_expires;
2618 * This check is repeated as we are holding onto the new bandwidth
2619 * while we unthrottle. This can potentially race with an unthrottled
2620 * group trying to acquire new bandwidth from the global pool.
2622 while (throttled && runtime > 0) {
2623 raw_spin_unlock(&cfs_b->lock);
2624 /* we can't nest cfs_b->lock while distributing bandwidth */
2625 runtime = distribute_cfs_runtime(cfs_b, runtime,
2627 raw_spin_lock(&cfs_b->lock);
2629 throttled = !list_empty(&cfs_b->throttled_cfs_rq);
2632 /* return (any) remaining runtime */
2633 cfs_b->runtime = runtime;
2635 * While we are ensured activity in the period following an
2636 * unthrottle, this also covers the case in which the new bandwidth is
2637 * insufficient to cover the existing bandwidth deficit. (Forcing the
2638 * timer to remain active while there are any throttled entities.)
2643 cfs_b->timer_active = 0;
2644 raw_spin_unlock(&cfs_b->lock);
2649 /* a cfs_rq won't donate quota below this amount */
2650 static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
2651 /* minimum remaining period time to redistribute slack quota */
2652 static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
2653 /* how long we wait to gather additional slack before distributing */
2654 static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
2656 /* are we near the end of the current quota period? */
2657 static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
2659 struct hrtimer *refresh_timer = &cfs_b->period_timer;
2662 /* if the call-back is running a quota refresh is already occurring */
2663 if (hrtimer_callback_running(refresh_timer))
2666 /* is a quota refresh about to occur? */
2667 remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
2668 if (remaining < min_expire)
2674 static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
2676 u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
2678 /* if there's a quota refresh soon don't bother with slack */
2679 if (runtime_refresh_within(cfs_b, min_left))
2682 start_bandwidth_timer(&cfs_b->slack_timer,
2683 ns_to_ktime(cfs_bandwidth_slack_period));
2686 /* we know any runtime found here is valid as update_curr() precedes return */
2687 static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2689 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2690 s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
2692 if (slack_runtime <= 0)
2695 raw_spin_lock(&cfs_b->lock);
2696 if (cfs_b->quota != RUNTIME_INF &&
2697 cfs_rq->runtime_expires == cfs_b->runtime_expires) {
2698 cfs_b->runtime += slack_runtime;
2700 /* we are under rq->lock, defer unthrottling using a timer */
2701 if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
2702 !list_empty(&cfs_b->throttled_cfs_rq))
2703 start_cfs_slack_bandwidth(cfs_b);
2705 raw_spin_unlock(&cfs_b->lock);
2707 /* even if it's not valid for return we don't want to try again */
2708 cfs_rq->runtime_remaining -= slack_runtime;
2711 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2713 if (!cfs_bandwidth_used())
2716 if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
2719 __return_cfs_rq_runtime(cfs_rq);
2723 * This is done with a timer (instead of inline with bandwidth return) since
2724 * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
2726 static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
2728 u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
2731 /* confirm we're still not at a refresh boundary */
2732 if (runtime_refresh_within(cfs_b, min_bandwidth_expiration))
2735 raw_spin_lock(&cfs_b->lock);
2736 if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) {
2737 runtime = cfs_b->runtime;
2740 expires = cfs_b->runtime_expires;
2741 raw_spin_unlock(&cfs_b->lock);
2746 runtime = distribute_cfs_runtime(cfs_b, runtime, expires);
2748 raw_spin_lock(&cfs_b->lock);
2749 if (expires == cfs_b->runtime_expires)
2750 cfs_b->runtime = runtime;
2751 raw_spin_unlock(&cfs_b->lock);
2755 * When a group wakes up we want to make sure that its quota is not already
2756 * expired/exceeded, otherwise it may be allowed to steal additional ticks of
2757 * runtime as update_curr() throttling can not not trigger until it's on-rq.
2759 static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
2761 if (!cfs_bandwidth_used())
2764 /* an active group must be handled by the update_curr()->put() path */
2765 if (!cfs_rq->runtime_enabled || cfs_rq->curr)
2768 /* ensure the group is not already throttled */
2769 if (cfs_rq_throttled(cfs_rq))
2772 /* update runtime allocation */
2773 account_cfs_rq_runtime(cfs_rq, 0);
2774 if (cfs_rq->runtime_remaining <= 0)
2775 throttle_cfs_rq(cfs_rq);
2778 /* conditionally throttle active cfs_rq's from put_prev_entity() */
2779 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2781 if (!cfs_bandwidth_used())
2784 if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
2788 * it's possible for a throttled entity to be forced into a running
2789 * state (e.g. set_curr_task), in this case we're finished.
2791 if (cfs_rq_throttled(cfs_rq))
2794 throttle_cfs_rq(cfs_rq);
2797 static inline u64 default_cfs_period(void);
2798 static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun);
2799 static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b);
2801 static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
2803 struct cfs_bandwidth *cfs_b =
2804 container_of(timer, struct cfs_bandwidth, slack_timer);
2805 do_sched_cfs_slack_timer(cfs_b);
2807 return HRTIMER_NORESTART;
2810 static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
2812 struct cfs_bandwidth *cfs_b =
2813 container_of(timer, struct cfs_bandwidth, period_timer);
2819 now = hrtimer_cb_get_time(timer);
2820 overrun = hrtimer_forward(timer, now, cfs_b->period);
2825 idle = do_sched_cfs_period_timer(cfs_b, overrun);
2828 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
2831 void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2833 raw_spin_lock_init(&cfs_b->lock);
2835 cfs_b->quota = RUNTIME_INF;
2836 cfs_b->period = ns_to_ktime(default_cfs_period());
2838 INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
2839 hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
2840 cfs_b->period_timer.function = sched_cfs_period_timer;
2841 hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
2842 cfs_b->slack_timer.function = sched_cfs_slack_timer;
2845 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2847 cfs_rq->runtime_enabled = 0;
2848 INIT_LIST_HEAD(&cfs_rq->throttled_list);
2851 /* requires cfs_b->lock, may release to reprogram timer */
2852 void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2855 * The timer may be active because we're trying to set a new bandwidth
2856 * period or because we're racing with the tear-down path
2857 * (timer_active==0 becomes visible before the hrtimer call-back
2858 * terminates). In either case we ensure that it's re-programmed
2860 while (unlikely(hrtimer_active(&cfs_b->period_timer))) {
2861 raw_spin_unlock(&cfs_b->lock);
2862 /* ensure cfs_b->lock is available while we wait */
2863 hrtimer_cancel(&cfs_b->period_timer);
2865 raw_spin_lock(&cfs_b->lock);
2866 /* if someone else restarted the timer then we're done */
2867 if (cfs_b->timer_active)
2871 cfs_b->timer_active = 1;
2872 start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period);
2875 static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2877 hrtimer_cancel(&cfs_b->period_timer);
2878 hrtimer_cancel(&cfs_b->slack_timer);
2881 static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
2883 struct cfs_rq *cfs_rq;
2885 for_each_leaf_cfs_rq(rq, cfs_rq) {
2886 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2888 if (!cfs_rq->runtime_enabled)
2892 * clock_task is not advancing so we just need to make sure
2893 * there's some valid quota amount
2895 cfs_rq->runtime_remaining = cfs_b->quota;
2896 if (cfs_rq_throttled(cfs_rq))
2897 unthrottle_cfs_rq(cfs_rq);
2901 #else /* CONFIG_CFS_BANDWIDTH */
2902 static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
2904 return rq_of(cfs_rq)->clock_task;
2907 static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
2908 unsigned long delta_exec) {}
2909 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2910 static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
2911 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2913 static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
2918 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
2923 static inline int throttled_lb_pair(struct task_group *tg,
2924 int src_cpu, int dest_cpu)
2929 void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
2931 #ifdef CONFIG_FAIR_GROUP_SCHED
2932 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2935 static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
2939 static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
2940 static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
2942 #endif /* CONFIG_CFS_BANDWIDTH */
2944 /**************************************************
2945 * CFS operations on tasks:
2948 #ifdef CONFIG_SCHED_HRTICK
2949 static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
2951 struct sched_entity *se = &p->se;
2952 struct cfs_rq *cfs_rq = cfs_rq_of(se);
2954 WARN_ON(task_rq(p) != rq);
2956 if (cfs_rq->nr_running > 1) {
2957 u64 slice = sched_slice(cfs_rq, se);
2958 u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
2959 s64 delta = slice - ran;
2968 * Don't schedule slices shorter than 10000ns, that just
2969 * doesn't make sense. Rely on vruntime for fairness.
2972 delta = max_t(s64, 10000LL, delta);
2974 hrtick_start(rq, delta);
2979 * called from enqueue/dequeue and updates the hrtick when the
2980 * current task is from our class and nr_running is low enough
2983 static void hrtick_update(struct rq *rq)
2985 struct task_struct *curr = rq->curr;
2987 if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class)
2990 if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
2991 hrtick_start_fair(rq, curr);
2993 #else /* !CONFIG_SCHED_HRTICK */
2995 hrtick_start_fair(struct rq *rq, struct task_struct *p)
2999 static inline void hrtick_update(struct rq *rq)
3005 * The enqueue_task method is called before nr_running is
3006 * increased. Here we update the fair scheduling stats and
3007 * then put the task into the rbtree:
3010 enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
3012 struct cfs_rq *cfs_rq;
3013 struct sched_entity *se = &p->se;
3015 for_each_sched_entity(se) {
3018 cfs_rq = cfs_rq_of(se);
3019 enqueue_entity(cfs_rq, se, flags);
3022 * end evaluation on encountering a throttled cfs_rq
3024 * note: in the case of encountering a throttled cfs_rq we will
3025 * post the final h_nr_running increment below.
3027 if (cfs_rq_throttled(cfs_rq))
3029 cfs_rq->h_nr_running++;
3031 flags = ENQUEUE_WAKEUP;
3034 for_each_sched_entity(se) {
3035 cfs_rq = cfs_rq_of(se);
3036 cfs_rq->h_nr_running++;
3038 if (cfs_rq_throttled(cfs_rq))
3041 update_cfs_shares(cfs_rq);
3042 update_entity_load_avg(se, 1);
3046 update_rq_runnable_avg(rq, rq->nr_running);
3052 static void set_next_buddy(struct sched_entity *se);
3055 * The dequeue_task method is called before nr_running is
3056 * decreased. We remove the task from the rbtree and
3057 * update the fair scheduling stats:
3059 static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
3061 struct cfs_rq *cfs_rq;
3062 struct sched_entity *se = &p->se;
3063 int task_sleep = flags & DEQUEUE_SLEEP;
3065 for_each_sched_entity(se) {
3066 cfs_rq = cfs_rq_of(se);
3067 dequeue_entity(cfs_rq, se, flags);
3070 * end evaluation on encountering a throttled cfs_rq
3072 * note: in the case of encountering a throttled cfs_rq we will
3073 * post the final h_nr_running decrement below.
3075 if (cfs_rq_throttled(cfs_rq))
3077 cfs_rq->h_nr_running--;
3079 /* Don't dequeue parent if it has other entities besides us */
3080 if (cfs_rq->load.weight) {
3082 * Bias pick_next to pick a task from this cfs_rq, as
3083 * p is sleeping when it is within its sched_slice.
3085 if (task_sleep && parent_entity(se))
3086 set_next_buddy(parent_entity(se));
3088 /* avoid re-evaluating load for this entity */
3089 se = parent_entity(se);
3092 flags |= DEQUEUE_SLEEP;
3095 for_each_sched_entity(se) {
3096 cfs_rq = cfs_rq_of(se);
3097 cfs_rq->h_nr_running--;
3099 if (cfs_rq_throttled(cfs_rq))
3102 update_cfs_shares(cfs_rq);
3103 update_entity_load_avg(se, 1);
3108 update_rq_runnable_avg(rq, 1);
3114 /* Used instead of source_load when we know the type == 0 */
3115 static unsigned long weighted_cpuload(const int cpu)
3117 return cpu_rq(cpu)->load.weight;
3121 * Return a low guess at the load of a migration-source cpu weighted
3122 * according to the scheduling class and "nice" value.
3124 * We want to under-estimate the load of migration sources, to
3125 * balance conservatively.
3127 static unsigned long source_load(int cpu, int type)
3129 struct rq *rq = cpu_rq(cpu);
3130 unsigned long total = weighted_cpuload(cpu);
3132 if (type == 0 || !sched_feat(LB_BIAS))
3135 return min(rq->cpu_load[type-1], total);
3139 * Return a high guess at the load of a migration-target cpu weighted
3140 * according to the scheduling class and "nice" value.
3142 static unsigned long target_load(int cpu, int type)
3144 struct rq *rq = cpu_rq(cpu);
3145 unsigned long total = weighted_cpuload(cpu);
3147 if (type == 0 || !sched_feat(LB_BIAS))
3150 return max(rq->cpu_load[type-1], total);
3153 static unsigned long power_of(int cpu)
3155 return cpu_rq(cpu)->cpu_power;
3158 static unsigned long cpu_avg_load_per_task(int cpu)
3160 struct rq *rq = cpu_rq(cpu);
3161 unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
3164 return rq->load.weight / nr_running;
3170 static void task_waking_fair(struct task_struct *p)
3172 struct sched_entity *se = &p->se;
3173 struct cfs_rq *cfs_rq = cfs_rq_of(se);
3176 #ifndef CONFIG_64BIT
3177 u64 min_vruntime_copy;
3180 min_vruntime_copy = cfs_rq->min_vruntime_copy;
3182 min_vruntime = cfs_rq->min_vruntime;
3183 } while (min_vruntime != min_vruntime_copy);
3185 min_vruntime = cfs_rq->min_vruntime;
3188 se->vruntime -= min_vruntime;
3191 #ifdef CONFIG_FAIR_GROUP_SCHED
3193 * effective_load() calculates the load change as seen from the root_task_group
3195 * Adding load to a group doesn't make a group heavier, but can cause movement
3196 * of group shares between cpus. Assuming the shares were perfectly aligned one
3197 * can calculate the shift in shares.
3199 * Calculate the effective load difference if @wl is added (subtracted) to @tg
3200 * on this @cpu and results in a total addition (subtraction) of @wg to the
3201 * total group weight.
3203 * Given a runqueue weight distribution (rw_i) we can compute a shares
3204 * distribution (s_i) using:
3206 * s_i = rw_i / \Sum rw_j (1)
3208 * Suppose we have 4 CPUs and our @tg is a direct child of the root group and
3209 * has 7 equal weight tasks, distributed as below (rw_i), with the resulting
3210 * shares distribution (s_i):
3212 * rw_i = { 2, 4, 1, 0 }
3213 * s_i = { 2/7, 4/7, 1/7, 0 }
3215 * As per wake_affine() we're interested in the load of two CPUs (the CPU the
3216 * task used to run on and the CPU the waker is running on), we need to
3217 * compute the effect of waking a task on either CPU and, in case of a sync
3218 * wakeup, compute the effect of the current task going to sleep.
3220 * So for a change of @wl to the local @cpu with an overall group weight change
3221 * of @wl we can compute the new shares distribution (s'_i) using:
3223 * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2)
3225 * Suppose we're interested in CPUs 0 and 1, and want to compute the load
3226 * differences in waking a task to CPU 0. The additional task changes the
3227 * weight and shares distributions like:
3229 * rw'_i = { 3, 4, 1, 0 }
3230 * s'_i = { 3/8, 4/8, 1/8, 0 }
3232 * We can then compute the difference in effective weight by using:
3234 * dw_i = S * (s'_i - s_i) (3)
3236 * Where 'S' is the group weight as seen by its parent.
3238 * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7)
3239 * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 -
3240 * 4/7) times the weight of the group.
3242 static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
3244 struct sched_entity *se = tg->se[cpu];
3246 if (!tg->parent) /* the trivial, non-cgroup case */
3249 for_each_sched_entity(se) {
3255 * W = @wg + \Sum rw_j
3257 W = wg + calc_tg_weight(tg, se->my_q);
3262 w = se->my_q->load.weight + wl;
3265 * wl = S * s'_i; see (2)
3268 wl = (w * tg->shares) / W;
3273 * Per the above, wl is the new se->load.weight value; since
3274 * those are clipped to [MIN_SHARES, ...) do so now. See
3275 * calc_cfs_shares().
3277 if (wl < MIN_SHARES)
3281 * wl = dw_i = S * (s'_i - s_i); see (3)
3283 wl -= se->load.weight;
3286 * Recursively apply this logic to all parent groups to compute
3287 * the final effective load change on the root group. Since
3288 * only the @tg group gets extra weight, all parent groups can
3289 * only redistribute existing shares. @wl is the shift in shares
3290 * resulting from this level per the above.
3299 static inline unsigned long effective_load(struct task_group *tg, int cpu,
3300 unsigned long wl, unsigned long wg)
3307 static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
3309 s64 this_load, load;
3310 int idx, this_cpu, prev_cpu;
3311 unsigned long tl_per_task;
3312 struct task_group *tg;
3313 unsigned long weight;
3317 this_cpu = smp_processor_id();
3318 prev_cpu = task_cpu(p);
3319 load = source_load(prev_cpu, idx);
3320 this_load = target_load(this_cpu, idx);
3323 * If sync wakeup then subtract the (maximum possible)
3324 * effect of the currently running task from the load
3325 * of the current CPU:
3328 tg = task_group(current);
3329 weight = current->se.load.weight;
3331 this_load += effective_load(tg, this_cpu, -weight, -weight);
3332 load += effective_load(tg, prev_cpu, 0, -weight);
3336 weight = p->se.load.weight;
3339 * In low-load situations, where prev_cpu is idle and this_cpu is idle
3340 * due to the sync cause above having dropped this_load to 0, we'll
3341 * always have an imbalance, but there's really nothing you can do
3342 * about that, so that's good too.
3344 * Otherwise check if either cpus are near enough in load to allow this
3345 * task to be woken on this_cpu.
3347 if (this_load > 0) {
3348 s64 this_eff_load, prev_eff_load;
3350 this_eff_load = 100;
3351 this_eff_load *= power_of(prev_cpu);
3352 this_eff_load *= this_load +
3353 effective_load(tg, this_cpu, weight, weight);
3355 prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2;
3356 prev_eff_load *= power_of(this_cpu);
3357 prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight);
3359 balanced = this_eff_load <= prev_eff_load;
3364 * If the currently running task will sleep within
3365 * a reasonable amount of time then attract this newly
3368 if (sync && balanced)
3371 schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
3372 tl_per_task = cpu_avg_load_per_task(this_cpu);
3375 (this_load <= load &&
3376 this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
3378 * This domain has SD_WAKE_AFFINE and
3379 * p is cache cold in this domain, and
3380 * there is no bad imbalance.
3382 schedstat_inc(sd, ttwu_move_affine);
3383 schedstat_inc(p, se.statistics.nr_wakeups_affine);
3391 * find_idlest_group finds and returns the least busy CPU group within the
3394 static struct sched_group *
3395 find_idlest_group(struct sched_domain *sd, struct task_struct *p,
3396 int this_cpu, int load_idx)
3398 struct sched_group *idlest = NULL, *group = sd->groups;
3399 unsigned long min_load = ULONG_MAX, this_load = 0;
3400 int imbalance = 100 + (sd->imbalance_pct-100)/2;
3403 unsigned long load, avg_load;
3407 /* Skip over this group if it has no CPUs allowed */
3408 if (!cpumask_intersects(sched_group_cpus(group),
3409 tsk_cpus_allowed(p)))
3412 local_group = cpumask_test_cpu(this_cpu,
3413 sched_group_cpus(group));
3415 /* Tally up the load of all CPUs in the group */
3418 for_each_cpu(i, sched_group_cpus(group)) {
3419 /* Bias balancing toward cpus of our domain */
3421 load = source_load(i, load_idx);
3423 load = target_load(i, load_idx);
3428 /* Adjust by relative CPU power of the group */
3429 avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power;
3432 this_load = avg_load;
3433 } else if (avg_load < min_load) {
3434 min_load = avg_load;
3437 } while (group = group->next, group != sd->groups);
3439 if (!idlest || 100*this_load < imbalance*min_load)
3445 * find_idlest_cpu - find the idlest cpu among the cpus in group.
3448 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
3450 unsigned long load, min_load = ULONG_MAX;
3454 /* Traverse only the allowed CPUs */
3455 for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) {
3456 load = weighted_cpuload(i);
3458 if (load < min_load || (load == min_load && i == this_cpu)) {
3468 * Try and locate an idle CPU in the sched_domain.
3470 static int select_idle_sibling(struct task_struct *p, int target)
3472 struct sched_domain *sd;
3473 struct sched_group *sg;
3474 int i = task_cpu(p);
3476 if (idle_cpu(target))
3480 * If the prevous cpu is cache affine and idle, don't be stupid.
3482 if (i != target && cpus_share_cache(i, target) && idle_cpu(i))
3486 * Otherwise, iterate the domains and find an elegible idle cpu.
3488 sd = rcu_dereference(per_cpu(sd_llc, target));
3489 for_each_lower_domain(sd) {
3492 if (!cpumask_intersects(sched_group_cpus(sg),
3493 tsk_cpus_allowed(p)))
3496 for_each_cpu(i, sched_group_cpus(sg)) {
3497 if (i == target || !idle_cpu(i))
3501 target = cpumask_first_and(sched_group_cpus(sg),
3502 tsk_cpus_allowed(p));
3506 } while (sg != sd->groups);
3512 #ifdef CONFIG_SCHED_HMP
3514 * Heterogenous multiprocessor (HMP) optimizations
3516 * The cpu types are distinguished using a list of hmp_domains
3517 * which each represent one cpu type using a cpumask.
3518 * The list is assumed ordered by compute capacity with the
3519 * fastest domain first.
3521 DEFINE_PER_CPU(struct hmp_domain *, hmp_cpu_domain);
3522 static const int hmp_max_tasks = 5;
3524 extern void __init arch_get_hmp_domains(struct list_head *hmp_domains_list);
3526 /* Setup hmp_domains */
3527 static int __init hmp_cpu_mask_setup(void)
3530 struct hmp_domain *domain;
3531 struct list_head *pos;
3534 pr_debug("Initializing HMP scheduler:\n");
3536 /* Initialize hmp_domains using platform code */
3537 arch_get_hmp_domains(&hmp_domains);
3538 if (list_empty(&hmp_domains)) {
3539 pr_debug("HMP domain list is empty!\n");
3543 /* Print hmp_domains */
3545 list_for_each(pos, &hmp_domains) {
3546 domain = list_entry(pos, struct hmp_domain, hmp_domains);
3547 cpulist_scnprintf(buf, 64, &domain->possible_cpus);
3548 pr_debug(" HMP domain %d: %s\n", dc, buf);
3550 for_each_cpu_mask(cpu, domain->possible_cpus) {
3551 per_cpu(hmp_cpu_domain, cpu) = domain;
3559 static struct hmp_domain *hmp_get_hmp_domain_for_cpu(int cpu)
3561 struct hmp_domain *domain;
3562 struct list_head *pos;
3564 list_for_each(pos, &hmp_domains) {
3565 domain = list_entry(pos, struct hmp_domain, hmp_domains);
3566 if(cpumask_test_cpu(cpu, &domain->possible_cpus))
3572 static void hmp_online_cpu(int cpu)
3574 struct hmp_domain *domain = hmp_get_hmp_domain_for_cpu(cpu);
3577 cpumask_set_cpu(cpu, &domain->cpus);
3580 static void hmp_offline_cpu(int cpu)
3582 struct hmp_domain *domain = hmp_get_hmp_domain_for_cpu(cpu);
3585 cpumask_clear_cpu(cpu, &domain->cpus);
3588 * Needed to determine heaviest tasks etc.
3590 static inline unsigned int hmp_cpu_is_fastest(int cpu);
3591 static inline unsigned int hmp_cpu_is_slowest(int cpu);
3592 static inline struct hmp_domain *hmp_slower_domain(int cpu);
3593 static inline struct hmp_domain *hmp_faster_domain(int cpu);
3595 /* must hold runqueue lock for queue se is currently on */
3596 static struct sched_entity *hmp_get_heaviest_task(
3597 struct sched_entity *se, int migrate_up)
3599 int num_tasks = hmp_max_tasks;
3600 struct sched_entity *max_se = se;
3601 unsigned long int max_ratio = se->avg.load_avg_ratio;
3602 const struct cpumask *hmp_target_mask = NULL;
3605 struct hmp_domain *hmp;
3606 if (hmp_cpu_is_fastest(cpu_of(se->cfs_rq->rq)))
3609 hmp = hmp_faster_domain(cpu_of(se->cfs_rq->rq));
3610 hmp_target_mask = &hmp->cpus;
3612 /* The currently running task is not on the runqueue */
3613 se = __pick_first_entity(cfs_rq_of(se));
3615 while (num_tasks && se) {
3616 if (entity_is_task(se) &&
3617 (se->avg.load_avg_ratio > max_ratio &&
3619 cpumask_intersects(hmp_target_mask,
3620 tsk_cpus_allowed(task_of(se))))) {
3622 max_ratio = se->avg.load_avg_ratio;
3624 se = __pick_next_entity(se);
3630 static struct sched_entity *hmp_get_lightest_task(
3631 struct sched_entity *se, int migrate_down)
3633 int num_tasks = hmp_max_tasks;
3634 struct sched_entity *min_se = se;
3635 unsigned long int min_ratio = se->avg.load_avg_ratio;
3636 const struct cpumask *hmp_target_mask = NULL;
3639 struct hmp_domain *hmp;
3640 if (hmp_cpu_is_slowest(cpu_of(se->cfs_rq->rq)))
3642 hmp = hmp_slower_domain(cpu_of(se->cfs_rq->rq));
3643 hmp_target_mask = &hmp->cpus;
3645 /* The currently running task is not on the runqueue */
3646 se = __pick_first_entity(cfs_rq_of(se));
3648 while (num_tasks && se) {
3649 if (entity_is_task(se) &&
3650 (se->avg.load_avg_ratio < min_ratio &&
3652 cpumask_intersects(hmp_target_mask,
3653 tsk_cpus_allowed(task_of(se))))) {
3655 min_ratio = se->avg.load_avg_ratio;
3657 se = __pick_next_entity(se);
3664 * Migration thresholds should be in the range [0..1023]
3665 * hmp_up_threshold: min. load required for migrating tasks to a faster cpu
3666 * hmp_down_threshold: max. load allowed for tasks migrating to a slower cpu
3668 * hmp_up_prio: Only up migrate task with high priority (<hmp_up_prio)
3669 * hmp_next_up_threshold: Delay before next up migration (1024 ~= 1 ms)
3670 * hmp_next_down_threshold: Delay before next down migration (1024 ~= 1 ms)
3672 unsigned int hmp_up_threshold = 700;
3673 unsigned int hmp_down_threshold = 512;
3674 #ifdef CONFIG_SCHED_HMP_PRIO_FILTER
3675 unsigned int hmp_up_prio = NICE_TO_PRIO(CONFIG_SCHED_HMP_PRIO_FILTER_VAL);
3677 unsigned int hmp_next_up_threshold = 4096;
3678 unsigned int hmp_next_down_threshold = 4096;
3680 static unsigned int hmp_up_migration(int cpu, int *target_cpu, struct sched_entity *se);
3681 static unsigned int hmp_down_migration(int cpu, struct sched_entity *se);
3682 static inline unsigned int hmp_domain_min_load(struct hmp_domain *hmpd,
3683 int *min_cpu, struct cpumask *affinity);
3685 /* Check if cpu is in fastest hmp_domain */
3686 static inline unsigned int hmp_cpu_is_fastest(int cpu)
3688 struct list_head *pos;
3690 pos = &hmp_cpu_domain(cpu)->hmp_domains;
3691 return pos == hmp_domains.next;
3694 /* Check if cpu is in slowest hmp_domain */
3695 static inline unsigned int hmp_cpu_is_slowest(int cpu)
3697 struct list_head *pos;
3699 pos = &hmp_cpu_domain(cpu)->hmp_domains;
3700 return list_is_last(pos, &hmp_domains);
3703 /* Next (slower) hmp_domain relative to cpu */
3704 static inline struct hmp_domain *hmp_slower_domain(int cpu)
3706 struct list_head *pos;
3708 pos = &hmp_cpu_domain(cpu)->hmp_domains;
3709 return list_entry(pos->next, struct hmp_domain, hmp_domains);
3712 /* Previous (faster) hmp_domain relative to cpu */
3713 static inline struct hmp_domain *hmp_faster_domain(int cpu)
3715 struct list_head *pos;
3717 pos = &hmp_cpu_domain(cpu)->hmp_domains;
3718 return list_entry(pos->prev, struct hmp_domain, hmp_domains);
3722 * Selects a cpu in previous (faster) hmp_domain
3724 static inline unsigned int hmp_select_faster_cpu(struct task_struct *tsk,
3727 int lowest_cpu=NR_CPUS;
3728 __always_unused int lowest_ratio;
3729 struct hmp_domain *hmp;
3731 if (hmp_cpu_is_fastest(cpu))
3732 hmp = hmp_cpu_domain(cpu);
3734 hmp = hmp_faster_domain(cpu);
3736 lowest_ratio = hmp_domain_min_load(hmp, &lowest_cpu,
3737 tsk_cpus_allowed(tsk));
3743 * Selects a cpu in next (slower) hmp_domain
3744 * Note that cpumask_any_and() returns the first cpu in the cpumask
3746 static inline unsigned int hmp_select_slower_cpu(struct task_struct *tsk,
3749 int lowest_cpu=NR_CPUS;
3750 struct hmp_domain *hmp;
3751 __always_unused int lowest_ratio;
3753 if (hmp_cpu_is_slowest(cpu))
3754 hmp = hmp_cpu_domain(cpu);
3756 hmp = hmp_slower_domain(cpu);
3758 lowest_ratio = hmp_domain_min_load(hmp, &lowest_cpu,
3759 tsk_cpus_allowed(tsk));
3764 static inline void hmp_next_up_delay(struct sched_entity *se, int cpu)
3766 /* hack - always use clock from first online CPU */
3767 u64 now = cpu_rq(cpumask_first(cpu_online_mask))->clock_task;
3768 se->avg.hmp_last_up_migration = now;
3769 se->avg.hmp_last_down_migration = 0;
3770 cpu_rq(cpu)->avg.hmp_last_up_migration = now;
3771 cpu_rq(cpu)->avg.hmp_last_down_migration = 0;
3774 static inline void hmp_next_down_delay(struct sched_entity *se, int cpu)
3776 /* hack - always use clock from first online CPU */
3777 u64 now = cpu_rq(cpumask_first(cpu_online_mask))->clock_task;
3778 se->avg.hmp_last_down_migration = now;
3779 se->avg.hmp_last_up_migration = 0;
3780 cpu_rq(cpu)->avg.hmp_last_down_migration = now;
3781 cpu_rq(cpu)->avg.hmp_last_up_migration = 0;
3784 #ifdef CONFIG_HMP_VARIABLE_SCALE
3786 * Heterogenous multiprocessor (HMP) optimizations
3788 * These functions allow to change the growing speed of the load_avg_ratio
3789 * by default it goes from 0 to 0.5 in LOAD_AVG_PERIOD = 32ms
3790 * This can now be changed with /sys/kernel/hmp/load_avg_period_ms.
3792 * These functions also allow to change the up and down threshold of HMP
3793 * using /sys/kernel/hmp/{up,down}_threshold.
3794 * Both must be between 0 and 1023. The threshold that is compared
3795 * to the load_avg_ratio is up_threshold/1024 and down_threshold/1024.
3797 * For instance, if load_avg_period = 64 and up_threshold = 512, an idle
3798 * task with a load of 0 will reach the threshold after 64ms of busy loop.
3800 * Changing load_avg_periods_ms has the same effect than changing the
3801 * default scaling factor Y=1002/1024 in the load_avg_ratio computation to
3802 * (1002/1024.0)^(LOAD_AVG_PERIOD/load_avg_period_ms), but the last one
3803 * could trigger overflows.
3804 * For instance, with Y = 1023/1024 in __update_task_entity_contrib()
3805 * "contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);"
3806 * could be overflowed for a weight > 2^12 even is the load_avg_contrib
3807 * should still be a 32bits result. This would not happen by multiplicating
3808 * delta time by 1/22 and setting load_avg_period_ms = 706.
3812 * By scaling the delta time it end-up increasing or decrease the
3813 * growing speed of the per entity load_avg_ratio
3814 * The scale factor hmp_data.multiplier is a fixed point
3815 * number: (32-HMP_VARIABLE_SCALE_SHIFT).HMP_VARIABLE_SCALE_SHIFT
3817 static u64 hmp_variable_scale_convert(u64 delta)
3819 u64 high = delta >> 32ULL;
3820 u64 low = delta & 0xffffffffULL;
3821 low *= hmp_data.multiplier;
3822 high *= hmp_data.multiplier;
3823 return (low >> HMP_VARIABLE_SCALE_SHIFT)
3824 + (high << (32ULL - HMP_VARIABLE_SCALE_SHIFT));
3827 static ssize_t hmp_show(struct kobject *kobj,
3828 struct attribute *attr, char *buf)
3831 struct hmp_global_attr *hmp_attr =
3832 container_of(attr, struct hmp_global_attr, attr);
3833 int temp = *(hmp_attr->value);
3834 if (hmp_attr->to_sysfs != NULL)
3835 temp = hmp_attr->to_sysfs(temp);
3836 ret = sprintf(buf, "%d\n", temp);
3840 static ssize_t hmp_store(struct kobject *a, struct attribute *attr,
3841 const char *buf, size_t count)
3844 ssize_t ret = count;
3845 struct hmp_global_attr *hmp_attr =
3846 container_of(attr, struct hmp_global_attr, attr);
3847 char *str = vmalloc(count + 1);
3850 memcpy(str, buf, count);
3852 if (sscanf(str, "%d", &temp) < 1)
3855 if (hmp_attr->from_sysfs != NULL)
3856 temp = hmp_attr->from_sysfs(temp);
3860 *(hmp_attr->value) = temp;
3866 static int hmp_period_tofrom_sysfs(int value)
3868 return (LOAD_AVG_PERIOD << HMP_VARIABLE_SCALE_SHIFT) / value;
3871 /* max value for threshold is 1024 */
3872 static int hmp_theshold_from_sysfs(int value)
3878 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
3879 /* freqinvar control is only 0,1 off/on */
3880 static int hmp_freqinvar_from_sysfs(int value)
3882 if (value < 0 || value > 1)
3887 static void hmp_attr_add(
3890 int (*to_sysfs)(int),
3891 int (*from_sysfs)(int))
3894 while (hmp_data.attributes[i] != NULL) {
3896 if (i >= HMP_DATA_SYSFS_MAX)
3899 hmp_data.attr[i].attr.mode = 0644;
3900 hmp_data.attr[i].show = hmp_show;
3901 hmp_data.attr[i].store = hmp_store;
3902 hmp_data.attr[i].attr.name = name;
3903 hmp_data.attr[i].value = value;
3904 hmp_data.attr[i].to_sysfs = to_sysfs;
3905 hmp_data.attr[i].from_sysfs = from_sysfs;
3906 hmp_data.attributes[i] = &hmp_data.attr[i].attr;
3907 hmp_data.attributes[i + 1] = NULL;
3910 static int hmp_attr_init(void)
3913 memset(&hmp_data, sizeof(hmp_data), 0);
3914 /* by default load_avg_period_ms == LOAD_AVG_PERIOD
3917 hmp_data.multiplier = hmp_period_tofrom_sysfs(LOAD_AVG_PERIOD);
3919 hmp_attr_add("load_avg_period_ms",
3920 &hmp_data.multiplier,
3921 hmp_period_tofrom_sysfs,
3922 hmp_period_tofrom_sysfs);
3923 hmp_attr_add("up_threshold",
3926 hmp_theshold_from_sysfs);
3927 hmp_attr_add("down_threshold",
3928 &hmp_down_threshold,
3930 hmp_theshold_from_sysfs);
3931 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
3932 /* default frequency-invariant scaling ON */
3933 hmp_data.freqinvar_load_scale_enabled = 1;
3934 hmp_attr_add("frequency_invariant_load_scale",
3935 &hmp_data.freqinvar_load_scale_enabled,
3937 hmp_freqinvar_from_sysfs);
3939 hmp_data.attr_group.name = "hmp";
3940 hmp_data.attr_group.attrs = hmp_data.attributes;
3941 ret = sysfs_create_group(kernel_kobj,
3942 &hmp_data.attr_group);
3945 late_initcall(hmp_attr_init);
3946 #endif /* CONFIG_HMP_VARIABLE_SCALE */
3948 * return the load of the lowest-loaded CPU in a given HMP domain
3949 * min_cpu optionally points to an int to receive the CPU.
3950 * affinity optionally points to a cpumask containing the
3951 * CPUs to be considered. note:
3952 * + min_cpu = NR_CPUS only if no CPUs are in the set of
3953 * affinity && hmp_domain cpus
3954 * + min_cpu will always otherwise equal one of the CPUs in
3956 * + when more than one CPU has the same load, the one which
3957 * is least-recently-disturbed by an HMP migration will be
3959 * + if all CPUs are equally loaded or idle and the times are
3960 * all the same, the first in the set will be used
3961 * + if affinity is not set, cpu_online_mask is used
3963 static inline unsigned int hmp_domain_min_load(struct hmp_domain *hmpd,
3964 int *min_cpu, struct cpumask *affinity)
3967 int min_cpu_runnable_temp = NR_CPUS;
3968 u64 min_target_last_migration = ULLONG_MAX;
3969 u64 curr_last_migration;
3970 unsigned long min_runnable_load = INT_MAX;
3971 unsigned long contrib;
3972 struct sched_avg *avg;
3973 struct cpumask temp_cpumask;
3975 * only look at CPUs allowed if specified,
3976 * otherwise look at all online CPUs in the
3979 cpumask_and(&temp_cpumask, &hmpd->cpus, affinity ? affinity : cpu_online_mask);
3981 for_each_cpu_mask(cpu, temp_cpumask) {
3982 avg = &cpu_rq(cpu)->avg;
3983 /* used for both up and down migration */
3984 curr_last_migration = avg->hmp_last_up_migration ?
3985 avg->hmp_last_up_migration : avg->hmp_last_down_migration;
3987 contrib = avg->load_avg_ratio;
3989 * Consider a runqueue completely busy if there is any load
3990 * on it. Definitely not the best for overall fairness, but
3991 * does well in typical Android use cases.
3996 if ((contrib < min_runnable_load) ||
3997 (contrib == min_runnable_load &&
3998 curr_last_migration < min_target_last_migration)) {
4000 * if the load is the same target the CPU with
4001 * the longest time since a migration.
4002 * This is to spread migration load between
4003 * members of a domain more evenly when the
4004 * domain is fully loaded
4006 min_runnable_load = contrib;
4007 min_cpu_runnable_temp = cpu;
4008 min_target_last_migration = curr_last_migration;
4013 *min_cpu = min_cpu_runnable_temp;
4015 return min_runnable_load;
4019 * Calculate the task starvation
4020 * This is the ratio of actually running time vs. runnable time.
4021 * If the two are equal the task is getting the cpu time it needs or
4022 * it is alone on the cpu and the cpu is fully utilized.
4024 static inline unsigned int hmp_task_starvation(struct sched_entity *se)
4028 starvation = se->avg.usage_avg_sum * scale_load_down(NICE_0_LOAD);
4029 starvation /= (se->avg.runnable_avg_sum + 1);
4031 return scale_load(starvation);
4034 static inline unsigned int hmp_offload_down(int cpu, struct sched_entity *se)
4037 int dest_cpu = NR_CPUS;
4039 if (hmp_cpu_is_slowest(cpu))
4042 /* Is there an idle CPU in the current domain */
4043 min_usage = hmp_domain_min_load(hmp_cpu_domain(cpu), NULL, NULL);
4044 if (min_usage == 0) {
4045 trace_sched_hmp_offload_abort(cpu, min_usage, "load");
4049 /* Is the task alone on the cpu? */
4050 if (cpu_rq(cpu)->cfs.h_nr_running < 2) {
4051 trace_sched_hmp_offload_abort(cpu,
4052 cpu_rq(cpu)->cfs.h_nr_running, "nr_running");
4056 /* Is the task actually starving? */
4057 /* >=25% ratio running/runnable = starving */
4058 if (hmp_task_starvation(se) > 768) {
4059 trace_sched_hmp_offload_abort(cpu, hmp_task_starvation(se),
4064 /* Does the slower domain have any idle CPUs? */
4065 min_usage = hmp_domain_min_load(hmp_slower_domain(cpu), &dest_cpu,
4066 tsk_cpus_allowed(task_of(se)));
4068 if (min_usage == 0) {
4069 trace_sched_hmp_offload_succeed(cpu, dest_cpu);
4072 trace_sched_hmp_offload_abort(cpu,min_usage,"slowdomain");
4075 #endif /* CONFIG_SCHED_HMP */
4078 * sched_balance_self: balance the current task (running on cpu) in domains
4079 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
4082 * Balance, ie. select the least loaded group.
4084 * Returns the target CPU number, or the same CPU if no balancing is needed.
4086 * preempt must be disabled.
4089 select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
4091 struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
4092 int cpu = smp_processor_id();
4093 int prev_cpu = task_cpu(p);
4095 int want_affine = 0;
4096 int sync = wake_flags & WF_SYNC;
4098 if (p->nr_cpus_allowed == 1)
4101 #ifdef CONFIG_SCHED_HMP
4102 /* always put non-kernel forking tasks on a big domain */
4103 if (p->mm && (sd_flag & SD_BALANCE_FORK)) {
4104 new_cpu = hmp_select_faster_cpu(p, prev_cpu);
4105 if (new_cpu != NR_CPUS) {
4106 hmp_next_up_delay(&p->se, new_cpu);
4109 /* failed to perform HMP fork balance, use normal balance */
4114 if (sd_flag & SD_BALANCE_WAKE) {
4115 if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
4121 for_each_domain(cpu, tmp) {
4122 if (!(tmp->flags & SD_LOAD_BALANCE))
4126 * If both cpu and prev_cpu are part of this domain,
4127 * cpu is a valid SD_WAKE_AFFINE target.
4129 if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
4130 cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
4135 if (tmp->flags & sd_flag)
4140 if (cpu != prev_cpu && wake_affine(affine_sd, p, sync))
4143 new_cpu = select_idle_sibling(p, prev_cpu);
4148 int load_idx = sd->forkexec_idx;
4149 struct sched_group *group;
4152 if (!(sd->flags & sd_flag)) {
4157 if (sd_flag & SD_BALANCE_WAKE)
4158 load_idx = sd->wake_idx;
4160 group = find_idlest_group(sd, p, cpu, load_idx);
4166 new_cpu = find_idlest_cpu(group, p, cpu);
4167 if (new_cpu == -1 || new_cpu == cpu) {
4168 /* Now try balancing at a lower domain level of cpu */
4173 /* Now try balancing at a lower domain level of new_cpu */
4175 weight = sd->span_weight;
4177 for_each_domain(cpu, tmp) {
4178 if (weight <= tmp->span_weight)
4180 if (tmp->flags & sd_flag)
4183 /* while loop will break here if sd == NULL */
4188 #ifdef CONFIG_SCHED_HMP
4189 prev_cpu = task_cpu(p);
4191 if (hmp_up_migration(prev_cpu, &new_cpu, &p->se)) {
4192 hmp_next_up_delay(&p->se, new_cpu);
4193 trace_sched_hmp_migrate(p, new_cpu, HMP_MIGRATE_WAKEUP);
4196 if (hmp_down_migration(prev_cpu, &p->se)) {
4197 new_cpu = hmp_select_slower_cpu(p, prev_cpu);
4198 hmp_next_down_delay(&p->se, new_cpu);
4199 trace_sched_hmp_migrate(p, new_cpu, HMP_MIGRATE_WAKEUP);
4202 /* Make sure that the task stays in its previous hmp domain */
4203 if (!cpumask_test_cpu(new_cpu, &hmp_cpu_domain(prev_cpu)->cpus))
4211 * Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
4212 * removed when useful for applications beyond shares distribution (e.g.
4215 #ifdef CONFIG_FAIR_GROUP_SCHED
4217 * Called immediately before a task is migrated to a new cpu; task_cpu(p) and
4218 * cfs_rq_of(p) references at time of call are still valid and identify the
4219 * previous cpu. However, the caller only guarantees p->pi_lock is held; no
4220 * other assumptions, including the state of rq->lock, should be made.
4223 migrate_task_rq_fair(struct task_struct *p, int next_cpu)
4225 struct sched_entity *se = &p->se;
4226 struct cfs_rq *cfs_rq = cfs_rq_of(se);
4229 * Load tracking: accumulate removed load so that it can be processed
4230 * when we next update owning cfs_rq under rq->lock. Tasks contribute
4231 * to blocked load iff they have a positive decay-count. It can never
4232 * be negative here since on-rq tasks have decay-count == 0.
4234 if (se->avg.decay_count) {
4235 se->avg.decay_count = -__synchronize_entity_decay(se);
4236 atomic64_add(se->avg.load_avg_contrib, &cfs_rq->removed_load);
4240 #endif /* CONFIG_SMP */
4242 static unsigned long
4243 wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
4245 unsigned long gran = sysctl_sched_wakeup_granularity;
4248 * Since its curr running now, convert the gran from real-time
4249 * to virtual-time in his units.
4251 * By using 'se' instead of 'curr' we penalize light tasks, so
4252 * they get preempted easier. That is, if 'se' < 'curr' then
4253 * the resulting gran will be larger, therefore penalizing the
4254 * lighter, if otoh 'se' > 'curr' then the resulting gran will
4255 * be smaller, again penalizing the lighter task.
4257 * This is especially important for buddies when the leftmost
4258 * task is higher priority than the buddy.
4260 return calc_delta_fair(gran, se);
4264 * Should 'se' preempt 'curr'.
4278 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
4280 s64 gran, vdiff = curr->vruntime - se->vruntime;
4285 gran = wakeup_gran(curr, se);
4292 static void set_last_buddy(struct sched_entity *se)
4294 if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
4297 for_each_sched_entity(se)
4298 cfs_rq_of(se)->last = se;
4301 static void set_next_buddy(struct sched_entity *se)
4303 if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
4306 for_each_sched_entity(se)
4307 cfs_rq_of(se)->next = se;
4310 static void set_skip_buddy(struct sched_entity *se)
4312 for_each_sched_entity(se)
4313 cfs_rq_of(se)->skip = se;
4317 * Preempt the current task with a newly woken task if needed:
4319 static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
4321 struct task_struct *curr = rq->curr;
4322 struct sched_entity *se = &curr->se, *pse = &p->se;
4323 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
4324 int scale = cfs_rq->nr_running >= sched_nr_latency;
4325 int next_buddy_marked = 0;
4327 if (unlikely(se == pse))
4331 * This is possible from callers such as move_task(), in which we
4332 * unconditionally check_prempt_curr() after an enqueue (which may have
4333 * lead to a throttle). This both saves work and prevents false
4334 * next-buddy nomination below.
4336 if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
4339 if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
4340 set_next_buddy(pse);
4341 next_buddy_marked = 1;
4345 * We can come here with TIF_NEED_RESCHED already set from new task
4348 * Note: this also catches the edge-case of curr being in a throttled
4349 * group (e.g. via set_curr_task), since update_curr() (in the
4350 * enqueue of curr) will have resulted in resched being set. This
4351 * prevents us from potentially nominating it as a false LAST_BUDDY
4354 if (test_tsk_need_resched(curr))
4357 /* Idle tasks are by definition preempted by non-idle tasks. */
4358 if (unlikely(curr->policy == SCHED_IDLE) &&
4359 likely(p->policy != SCHED_IDLE))
4363 * Batch and idle tasks do not preempt non-idle tasks (their preemption
4364 * is driven by the tick):
4366 if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
4369 find_matching_se(&se, &pse);
4370 update_curr(cfs_rq_of(se));
4372 if (wakeup_preempt_entity(se, pse) == 1) {
4374 * Bias pick_next to pick the sched entity that is
4375 * triggering this preemption.
4377 if (!next_buddy_marked)
4378 set_next_buddy(pse);
4387 * Only set the backward buddy when the current task is still
4388 * on the rq. This can happen when a wakeup gets interleaved
4389 * with schedule on the ->pre_schedule() or idle_balance()
4390 * point, either of which can * drop the rq lock.
4392 * Also, during early boot the idle thread is in the fair class,
4393 * for obvious reasons its a bad idea to schedule back to it.
4395 if (unlikely(!se->on_rq || curr == rq->idle))
4398 if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
4402 static struct task_struct *pick_next_task_fair(struct rq *rq)
4404 struct task_struct *p;
4405 struct cfs_rq *cfs_rq = &rq->cfs;
4406 struct sched_entity *se;
4408 if (!cfs_rq->nr_running)
4412 se = pick_next_entity(cfs_rq);
4413 set_next_entity(cfs_rq, se);
4414 cfs_rq = group_cfs_rq(se);
4418 if (hrtick_enabled(rq))
4419 hrtick_start_fair(rq, p);
4425 * Account for a descheduled task:
4427 static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
4429 struct sched_entity *se = &prev->se;
4430 struct cfs_rq *cfs_rq;
4432 for_each_sched_entity(se) {
4433 cfs_rq = cfs_rq_of(se);
4434 put_prev_entity(cfs_rq, se);
4439 * sched_yield() is very simple
4441 * The magic of dealing with the ->skip buddy is in pick_next_entity.
4443 static void yield_task_fair(struct rq *rq)
4445 struct task_struct *curr = rq->curr;
4446 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
4447 struct sched_entity *se = &curr->se;
4450 * Are we the only task in the tree?
4452 if (unlikely(rq->nr_running == 1))
4455 clear_buddies(cfs_rq, se);
4457 if (curr->policy != SCHED_BATCH) {
4458 update_rq_clock(rq);
4460 * Update run-time statistics of the 'current'.
4462 update_curr(cfs_rq);
4464 * Tell update_rq_clock() that we've just updated,
4465 * so we don't do microscopic update in schedule()
4466 * and double the fastpath cost.
4468 rq->skip_clock_update = 1;
4474 static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt)
4476 struct sched_entity *se = &p->se;
4478 /* throttled hierarchies are not runnable */
4479 if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
4482 /* Tell the scheduler that we'd really like pse to run next. */
4485 yield_task_fair(rq);
4491 /**************************************************
4492 * Fair scheduling class load-balancing methods.
4496 * The purpose of load-balancing is to achieve the same basic fairness the
4497 * per-cpu scheduler provides, namely provide a proportional amount of compute
4498 * time to each task. This is expressed in the following equation:
4500 * W_i,n/P_i == W_j,n/P_j for all i,j (1)
4502 * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight
4503 * W_i,0 is defined as:
4505 * W_i,0 = \Sum_j w_i,j (2)
4507 * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight
4508 * is derived from the nice value as per prio_to_weight[].
4510 * The weight average is an exponential decay average of the instantaneous
4513 * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3)
4515 * P_i is the cpu power (or compute capacity) of cpu i, typically it is the
4516 * fraction of 'recent' time available for SCHED_OTHER task execution. But it
4517 * can also include other factors [XXX].
4519 * To achieve this balance we define a measure of imbalance which follows
4520 * directly from (1):
4522 * imb_i,j = max{ avg(W/P), W_i/P_i } - min{ avg(W/P), W_j/P_j } (4)
4524 * We them move tasks around to minimize the imbalance. In the continuous
4525 * function space it is obvious this converges, in the discrete case we get
4526 * a few fun cases generally called infeasible weight scenarios.
4529 * - infeasible weights;
4530 * - local vs global optima in the discrete case. ]
4535 * In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
4536 * for all i,j solution, we create a tree of cpus that follows the hardware
4537 * topology where each level pairs two lower groups (or better). This results
4538 * in O(log n) layers. Furthermore we reduce the number of cpus going up the
4539 * tree to only the first of the previous level and we decrease the frequency
4540 * of load-balance at each level inv. proportional to the number of cpus in
4546 * \Sum { --- * --- * 2^i } = O(n) (5)
4548 * `- size of each group
4549 * | | `- number of cpus doing load-balance
4551 * `- sum over all levels
4553 * Coupled with a limit on how many tasks we can migrate every balance pass,
4554 * this makes (5) the runtime complexity of the balancer.
4556 * An important property here is that each CPU is still (indirectly) connected
4557 * to every other cpu in at most O(log n) steps:
4559 * The adjacency matrix of the resulting graph is given by:
4562 * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6)
4565 * And you'll find that:
4567 * A^(log_2 n)_i,j != 0 for all i,j (7)
4569 * Showing there's indeed a path between every cpu in at most O(log n) steps.
4570 * The task movement gives a factor of O(m), giving a convergence complexity
4573 * O(nm log n), n := nr_cpus, m := nr_tasks (8)
4578 * In order to avoid CPUs going idle while there's still work to do, new idle
4579 * balancing is more aggressive and has the newly idle cpu iterate up the domain
4580 * tree itself instead of relying on other CPUs to bring it work.
4582 * This adds some complexity to both (5) and (8) but it reduces the total idle
4590 * Cgroups make a horror show out of (2), instead of a simple sum we get:
4593 * W_i,0 = \Sum_j \Prod_k w_k * ----- (9)
4598 * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10)
4600 * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i.
4602 * The big problem is S_k, its a global sum needed to compute a local (W_i)
4605 * [XXX write more on how we solve this.. _after_ merging pjt's patches that
4606 * rewrite all of this once again.]
4609 static unsigned long __read_mostly max_load_balance_interval = HZ/10;
4611 #define LBF_ALL_PINNED 0x01
4612 #define LBF_NEED_BREAK 0x02
4613 #define LBF_SOME_PINNED 0x04
4616 struct sched_domain *sd;
4624 struct cpumask *dst_grpmask;
4626 enum cpu_idle_type idle;
4628 /* The set of CPUs under consideration for load-balancing */
4629 struct cpumask *cpus;
4634 unsigned int loop_break;
4635 unsigned int loop_max;
4639 * move_task - move a task from one runqueue to another runqueue.
4640 * Both runqueues must be locked.
4642 static void move_task(struct task_struct *p, struct lb_env *env)
4644 deactivate_task(env->src_rq, p, 0);
4645 set_task_cpu(p, env->dst_cpu);
4646 activate_task(env->dst_rq, p, 0);
4647 check_preempt_curr(env->dst_rq, p, 0);
4651 * Is this task likely cache-hot:
4654 task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
4658 if (p->sched_class != &fair_sched_class)
4661 if (unlikely(p->policy == SCHED_IDLE))
4665 * Buddy candidates are cache hot:
4667 if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running &&
4668 (&p->se == cfs_rq_of(&p->se)->next ||
4669 &p->se == cfs_rq_of(&p->se)->last))
4672 if (sysctl_sched_migration_cost == -1)
4674 if (sysctl_sched_migration_cost == 0)
4677 delta = now - p->se.exec_start;
4679 return delta < (s64)sysctl_sched_migration_cost;
4683 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
4686 int can_migrate_task(struct task_struct *p, struct lb_env *env)
4688 int tsk_cache_hot = 0;
4690 * We do not migrate tasks that are:
4691 * 1) throttled_lb_pair, or
4692 * 2) cannot be migrated to this CPU due to cpus_allowed, or
4693 * 3) running (obviously), or
4694 * 4) are cache-hot on their current CPU.
4696 if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
4699 if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
4702 schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
4705 * Remember if this task can be migrated to any other cpu in
4706 * our sched_group. We may want to revisit it if we couldn't
4707 * meet load balance goals by pulling other tasks on src_cpu.
4709 * Also avoid computing new_dst_cpu if we have already computed
4710 * one in current iteration.
4712 if (!env->dst_grpmask || (env->flags & LBF_SOME_PINNED))
4715 /* Prevent to re-select dst_cpu via env's cpus */
4716 for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) {
4717 if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) {
4718 env->flags |= LBF_SOME_PINNED;
4719 env->new_dst_cpu = cpu;
4727 /* Record that we found atleast one task that could run on dst_cpu */
4728 env->flags &= ~LBF_ALL_PINNED;
4730 if (task_running(env->src_rq, p)) {
4731 schedstat_inc(p, se.statistics.nr_failed_migrations_running);
4736 * Aggressive migration if:
4737 * 1) task is cache cold, or
4738 * 2) too many balance attempts have failed.
4740 tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
4741 if (!tsk_cache_hot ||
4742 env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
4744 if (tsk_cache_hot) {
4745 schedstat_inc(env->sd, lb_hot_gained[env->idle]);
4746 schedstat_inc(p, se.statistics.nr_forced_migrations);
4752 schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
4757 * move_one_task tries to move exactly one task from busiest to this_rq, as
4758 * part of active balancing operations within "domain".
4759 * Returns 1 if successful and 0 otherwise.
4761 * Called with both runqueues locked.
4763 static int move_one_task(struct lb_env *env)
4765 struct task_struct *p, *n;
4767 list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
4768 if (!can_migrate_task(p, env))
4773 * Right now, this is only the second place move_task()
4774 * is called, so we can safely collect move_task()
4775 * stats here rather than inside move_task().
4777 schedstat_inc(env->sd, lb_gained[env->idle]);
4783 static unsigned long task_h_load(struct task_struct *p);
4785 static const unsigned int sched_nr_migrate_break = 32;
4788 * move_tasks tries to move up to imbalance weighted load from busiest to
4789 * this_rq, as part of a balancing operation within domain "sd".
4790 * Returns 1 if successful and 0 otherwise.
4792 * Called with both runqueues locked.
4794 static int move_tasks(struct lb_env *env)
4796 struct list_head *tasks = &env->src_rq->cfs_tasks;
4797 struct task_struct *p;
4801 if (env->imbalance <= 0)
4804 while (!list_empty(tasks)) {
4805 p = list_first_entry(tasks, struct task_struct, se.group_node);
4808 /* We've more or less seen every task there is, call it quits */
4809 if (env->loop > env->loop_max)
4812 /* take a breather every nr_migrate tasks */
4813 if (env->loop > env->loop_break) {
4814 env->loop_break += sched_nr_migrate_break;
4815 env->flags |= LBF_NEED_BREAK;
4819 if (!can_migrate_task(p, env))
4822 load = task_h_load(p);
4824 if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed)
4827 if ((load / 2) > env->imbalance)
4832 env->imbalance -= load;
4834 #ifdef CONFIG_PREEMPT
4836 * NEWIDLE balancing is a source of latency, so preemptible
4837 * kernels will stop after the first task is pulled to minimize
4838 * the critical section.
4840 if (env->idle == CPU_NEWLY_IDLE)
4845 * We only want to steal up to the prescribed amount of
4848 if (env->imbalance <= 0)
4853 list_move_tail(&p->se.group_node, tasks);
4857 * Right now, this is one of only two places move_task() is called,
4858 * so we can safely collect move_task() stats here rather than
4859 * inside move_task().
4861 schedstat_add(env->sd, lb_gained[env->idle], pulled);
4866 #ifdef CONFIG_FAIR_GROUP_SCHED
4868 * update tg->load_weight by folding this cpu's load_avg
4870 static void __update_blocked_averages_cpu(struct task_group *tg, int cpu)
4872 struct sched_entity *se = tg->se[cpu];
4873 struct cfs_rq *cfs_rq = tg->cfs_rq[cpu];
4875 /* throttled entities do not contribute to load */
4876 if (throttled_hierarchy(cfs_rq))
4879 update_cfs_rq_blocked_load(cfs_rq, 1);
4882 update_entity_load_avg(se, 1);
4884 * We pivot on our runnable average having decayed to zero for
4885 * list removal. This generally implies that all our children
4886 * have also been removed (modulo rounding error or bandwidth
4887 * control); however, such cases are rare and we can fix these
4890 * TODO: fix up out-of-order children on enqueue.
4892 if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running)
4893 list_del_leaf_cfs_rq(cfs_rq);
4895 struct rq *rq = rq_of(cfs_rq);
4896 update_rq_runnable_avg(rq, rq->nr_running);
4900 static void update_blocked_averages(int cpu)
4902 struct rq *rq = cpu_rq(cpu);
4903 struct cfs_rq *cfs_rq;
4904 unsigned long flags;
4906 raw_spin_lock_irqsave(&rq->lock, flags);
4907 update_rq_clock(rq);
4909 * Iterates the task_group tree in a bottom up fashion, see
4910 * list_add_leaf_cfs_rq() for details.
4912 for_each_leaf_cfs_rq(rq, cfs_rq) {
4914 * Note: We may want to consider periodically releasing
4915 * rq->lock about these updates so that creating many task
4916 * groups does not result in continually extending hold time.
4918 __update_blocked_averages_cpu(cfs_rq->tg, rq->cpu);
4921 raw_spin_unlock_irqrestore(&rq->lock, flags);
4925 * Compute the cpu's hierarchical load factor for each task group.
4926 * This needs to be done in a top-down fashion because the load of a child
4927 * group is a fraction of its parents load.
4929 static int tg_load_down(struct task_group *tg, void *data)
4932 long cpu = (long)data;
4935 load = cpu_rq(cpu)->load.weight;
4937 load = tg->parent->cfs_rq[cpu]->h_load;
4938 load *= tg->se[cpu]->load.weight;
4939 load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
4942 tg->cfs_rq[cpu]->h_load = load;
4947 static void update_h_load(long cpu)
4949 struct rq *rq = cpu_rq(cpu);
4950 unsigned long now = jiffies;
4952 if (rq->h_load_throttle == now)
4955 rq->h_load_throttle = now;
4958 walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
4962 static unsigned long task_h_load(struct task_struct *p)
4964 struct cfs_rq *cfs_rq = task_cfs_rq(p);
4967 load = p->se.load.weight;
4968 load = div_u64(load * cfs_rq->h_load, cfs_rq->load.weight + 1);
4973 static inline void update_blocked_averages(int cpu)
4977 static inline void update_h_load(long cpu)
4981 static unsigned long task_h_load(struct task_struct *p)
4983 return p->se.load.weight;
4987 /********** Helpers for find_busiest_group ************************/
4989 * sd_lb_stats - Structure to store the statistics of a sched_domain
4990 * during load balancing.
4992 struct sd_lb_stats {
4993 struct sched_group *busiest; /* Busiest group in this sd */
4994 struct sched_group *this; /* Local group in this sd */
4995 unsigned long total_load; /* Total load of all groups in sd */
4996 unsigned long total_pwr; /* Total power of all groups in sd */
4997 unsigned long avg_load; /* Average load across all groups in sd */
4999 /** Statistics of this group */
5000 unsigned long this_load;
5001 unsigned long this_load_per_task;
5002 unsigned long this_nr_running;
5003 unsigned long this_has_capacity;
5004 unsigned int this_idle_cpus;
5006 /* Statistics of the busiest group */
5007 unsigned int busiest_idle_cpus;
5008 unsigned long max_load;
5009 unsigned long busiest_load_per_task;
5010 unsigned long busiest_nr_running;
5011 unsigned long busiest_group_capacity;
5012 unsigned long busiest_has_capacity;
5013 unsigned int busiest_group_weight;
5015 int group_imb; /* Is there imbalance in this sd */
5019 * sg_lb_stats - stats of a sched_group required for load_balancing
5021 struct sg_lb_stats {
5022 unsigned long avg_load; /*Avg load across the CPUs of the group */
5023 unsigned long group_load; /* Total load over the CPUs of the group */
5024 unsigned long sum_nr_running; /* Nr tasks running in the group */
5025 unsigned long sum_weighted_load; /* Weighted load of group's tasks */
5026 unsigned long group_capacity;
5027 unsigned long idle_cpus;
5028 unsigned long group_weight;
5029 int group_imb; /* Is there an imbalance in the group ? */
5030 int group_has_capacity; /* Is there extra capacity in the group? */
5034 * get_sd_load_idx - Obtain the load index for a given sched domain.
5035 * @sd: The sched_domain whose load_idx is to be obtained.
5036 * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
5038 static inline int get_sd_load_idx(struct sched_domain *sd,
5039 enum cpu_idle_type idle)
5045 load_idx = sd->busy_idx;
5048 case CPU_NEWLY_IDLE:
5049 load_idx = sd->newidle_idx;
5052 load_idx = sd->idle_idx;
5059 static unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
5061 return SCHED_POWER_SCALE;
5064 unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
5066 return default_scale_freq_power(sd, cpu);
5069 static unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
5071 unsigned long weight = sd->span_weight;
5072 unsigned long smt_gain = sd->smt_gain;
5079 unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
5081 return default_scale_smt_power(sd, cpu);
5084 static unsigned long scale_rt_power(int cpu)
5086 struct rq *rq = cpu_rq(cpu);
5087 u64 total, available, age_stamp, avg;
5090 * Since we're reading these variables without serialization make sure
5091 * we read them once before doing sanity checks on them.
5093 age_stamp = ACCESS_ONCE(rq->age_stamp);
5094 avg = ACCESS_ONCE(rq->rt_avg);
5096 total = sched_avg_period() + (rq->clock - age_stamp);
5098 if (unlikely(total < avg)) {
5099 /* Ensures that power won't end up being negative */
5102 available = total - avg;
5105 if (unlikely((s64)total < SCHED_POWER_SCALE))
5106 total = SCHED_POWER_SCALE;
5108 total >>= SCHED_POWER_SHIFT;
5110 return div_u64(available, total);
5113 static void update_cpu_power(struct sched_domain *sd, int cpu)
5115 unsigned long weight = sd->span_weight;
5116 unsigned long power = SCHED_POWER_SCALE;
5117 struct sched_group *sdg = sd->groups;
5119 if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
5120 if (sched_feat(ARCH_POWER))
5121 power *= arch_scale_smt_power(sd, cpu);
5123 power *= default_scale_smt_power(sd, cpu);
5125 power >>= SCHED_POWER_SHIFT;
5128 sdg->sgp->power_orig = power;
5130 if (sched_feat(ARCH_POWER))
5131 power *= arch_scale_freq_power(sd, cpu);
5133 power *= default_scale_freq_power(sd, cpu);
5135 power >>= SCHED_POWER_SHIFT;
5137 power *= scale_rt_power(cpu);
5138 power >>= SCHED_POWER_SHIFT;
5143 cpu_rq(cpu)->cpu_power = power;
5144 sdg->sgp->power = power;
5147 void update_group_power(struct sched_domain *sd, int cpu)
5149 struct sched_domain *child = sd->child;
5150 struct sched_group *group, *sdg = sd->groups;
5151 unsigned long power;
5152 unsigned long interval;
5154 interval = msecs_to_jiffies(sd->balance_interval);
5155 interval = clamp(interval, 1UL, max_load_balance_interval);
5156 sdg->sgp->next_update = jiffies + interval;
5159 update_cpu_power(sd, cpu);
5165 if (child->flags & SD_OVERLAP) {
5167 * SD_OVERLAP domains cannot assume that child groups
5168 * span the current group.
5171 for_each_cpu(cpu, sched_group_cpus(sdg))
5172 power += power_of(cpu);
5175 * !SD_OVERLAP domains can assume that child groups
5176 * span the current group.
5179 group = child->groups;
5181 power += group->sgp->power;
5182 group = group->next;
5183 } while (group != child->groups);
5186 sdg->sgp->power_orig = sdg->sgp->power = power;
5190 * Try and fix up capacity for tiny siblings, this is needed when
5191 * things like SD_ASYM_PACKING need f_b_g to select another sibling
5192 * which on its own isn't powerful enough.
5194 * See update_sd_pick_busiest() and check_asym_packing().
5197 fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
5200 * Only siblings can have significantly less than SCHED_POWER_SCALE
5202 if (!(sd->flags & SD_SHARE_CPUPOWER))
5206 * If ~90% of the cpu_power is still there, we're good.
5208 if (group->sgp->power * 32 > group->sgp->power_orig * 29)
5215 * update_sg_lb_stats - Update sched_group's statistics for load balancing.
5216 * @env: The load balancing environment.
5217 * @group: sched_group whose statistics are to be updated.
5218 * @load_idx: Load index of sched_domain of this_cpu for load calc.
5219 * @local_group: Does group contain this_cpu.
5220 * @balance: Should we balance.
5221 * @sgs: variable to hold the statistics for this group.
5223 static inline void update_sg_lb_stats(struct lb_env *env,
5224 struct sched_group *group, int load_idx,
5225 int local_group, int *balance, struct sg_lb_stats *sgs)
5227 unsigned long nr_running, max_nr_running, min_nr_running;
5228 unsigned long load, max_cpu_load, min_cpu_load;
5229 unsigned int balance_cpu = -1, first_idle_cpu = 0;
5230 unsigned long avg_load_per_task = 0;
5234 balance_cpu = group_balance_cpu(group);
5236 /* Tally up the load of all CPUs in the group */
5238 min_cpu_load = ~0UL;
5240 min_nr_running = ~0UL;
5242 for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
5243 struct rq *rq = cpu_rq(i);
5245 nr_running = rq->nr_running;
5247 /* Bias balancing toward cpus of our domain */
5249 if (idle_cpu(i) && !first_idle_cpu &&
5250 cpumask_test_cpu(i, sched_group_mask(group))) {
5255 load = target_load(i, load_idx);
5257 load = source_load(i, load_idx);
5258 if (load > max_cpu_load)
5259 max_cpu_load = load;
5260 if (min_cpu_load > load)
5261 min_cpu_load = load;
5263 if (nr_running > max_nr_running)
5264 max_nr_running = nr_running;
5265 if (min_nr_running > nr_running)
5266 min_nr_running = nr_running;
5269 sgs->group_load += load;
5270 sgs->sum_nr_running += nr_running;
5271 sgs->sum_weighted_load += weighted_cpuload(i);
5277 * First idle cpu or the first cpu(busiest) in this sched group
5278 * is eligible for doing load balancing at this and above
5279 * domains. In the newly idle case, we will allow all the cpu's
5280 * to do the newly idle load balance.
5283 if (env->idle != CPU_NEWLY_IDLE) {
5284 if (balance_cpu != env->dst_cpu) {
5288 update_group_power(env->sd, env->dst_cpu);
5289 } else if (time_after_eq(jiffies, group->sgp->next_update))
5290 update_group_power(env->sd, env->dst_cpu);
5293 /* Adjust by relative CPU power of the group */
5294 sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;
5297 * Consider the group unbalanced when the imbalance is larger
5298 * than the average weight of a task.
5300 * APZ: with cgroup the avg task weight can vary wildly and
5301 * might not be a suitable number - should we keep a
5302 * normalized nr_running number somewhere that negates
5305 if (sgs->sum_nr_running)
5306 avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
5308 if ((max_cpu_load - min_cpu_load) >= avg_load_per_task &&
5309 (max_nr_running - min_nr_running) > 1)
5312 sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
5314 if (!sgs->group_capacity)
5315 sgs->group_capacity = fix_small_capacity(env->sd, group);
5316 sgs->group_weight = group->group_weight;
5318 if (sgs->group_capacity > sgs->sum_nr_running)
5319 sgs->group_has_capacity = 1;
5323 * update_sd_pick_busiest - return 1 on busiest group
5324 * @env: The load balancing environment.
5325 * @sds: sched_domain statistics
5326 * @sg: sched_group candidate to be checked for being the busiest
5327 * @sgs: sched_group statistics
5329 * Determine if @sg is a busier group than the previously selected
5332 static bool update_sd_pick_busiest(struct lb_env *env,
5333 struct sd_lb_stats *sds,
5334 struct sched_group *sg,
5335 struct sg_lb_stats *sgs)
5337 if (sgs->avg_load <= sds->max_load)
5340 if (sgs->sum_nr_running > sgs->group_capacity)
5347 * ASYM_PACKING needs to move all the work to the lowest
5348 * numbered CPUs in the group, therefore mark all groups
5349 * higher than ourself as busy.
5351 if ((env->sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running &&
5352 env->dst_cpu < group_first_cpu(sg)) {
5356 if (group_first_cpu(sds->busiest) > group_first_cpu(sg))
5364 * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
5365 * @env: The load balancing environment.
5366 * @balance: Should we balance.
5367 * @sds: variable to hold the statistics for this sched_domain.
5369 static inline void update_sd_lb_stats(struct lb_env *env,
5370 int *balance, struct sd_lb_stats *sds)
5372 struct sched_domain *child = env->sd->child;
5373 struct sched_group *sg = env->sd->groups;
5374 struct sg_lb_stats sgs;
5375 int load_idx, prefer_sibling = 0;
5377 if (child && child->flags & SD_PREFER_SIBLING)
5380 load_idx = get_sd_load_idx(env->sd, env->idle);
5385 local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg));
5386 memset(&sgs, 0, sizeof(sgs));
5387 update_sg_lb_stats(env, sg, load_idx, local_group, balance, &sgs);
5389 if (local_group && !(*balance))
5392 sds->total_load += sgs.group_load;
5393 sds->total_pwr += sg->sgp->power;
5396 * In case the child domain prefers tasks go to siblings
5397 * first, lower the sg capacity to one so that we'll try
5398 * and move all the excess tasks away. We lower the capacity
5399 * of a group only if the local group has the capacity to fit
5400 * these excess tasks, i.e. nr_running < group_capacity. The
5401 * extra check prevents the case where you always pull from the
5402 * heaviest group when it is already under-utilized (possible
5403 * with a large weight task outweighs the tasks on the system).
5405 if (prefer_sibling && !local_group && sds->this_has_capacity)
5406 sgs.group_capacity = min(sgs.group_capacity, 1UL);
5409 sds->this_load = sgs.avg_load;
5411 sds->this_nr_running = sgs.sum_nr_running;
5412 sds->this_load_per_task = sgs.sum_weighted_load;
5413 sds->this_has_capacity = sgs.group_has_capacity;
5414 sds->this_idle_cpus = sgs.idle_cpus;
5415 } else if (update_sd_pick_busiest(env, sds, sg, &sgs)) {
5416 sds->max_load = sgs.avg_load;
5418 sds->busiest_nr_running = sgs.sum_nr_running;
5419 sds->busiest_idle_cpus = sgs.idle_cpus;
5420 sds->busiest_group_capacity = sgs.group_capacity;
5421 sds->busiest_load_per_task = sgs.sum_weighted_load;
5422 sds->busiest_has_capacity = sgs.group_has_capacity;
5423 sds->busiest_group_weight = sgs.group_weight;
5424 sds->group_imb = sgs.group_imb;
5428 } while (sg != env->sd->groups);
5432 * check_asym_packing - Check to see if the group is packed into the
5435 * This is primarily intended to used at the sibling level. Some
5436 * cores like POWER7 prefer to use lower numbered SMT threads. In the
5437 * case of POWER7, it can move to lower SMT modes only when higher
5438 * threads are idle. When in lower SMT modes, the threads will
5439 * perform better since they share less core resources. Hence when we
5440 * have idle threads, we want them to be the higher ones.
5442 * This packing function is run on idle threads. It checks to see if
5443 * the busiest CPU in this domain (core in the P7 case) has a higher
5444 * CPU number than the packing function is being run on. Here we are
5445 * assuming lower CPU number will be equivalent to lower a SMT thread
5448 * Returns 1 when packing is required and a task should be moved to
5449 * this CPU. The amount of the imbalance is returned in *imbalance.
5451 * @env: The load balancing environment.
5452 * @sds: Statistics of the sched_domain which is to be packed
5454 static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
5458 if (!(env->sd->flags & SD_ASYM_PACKING))
5464 busiest_cpu = group_first_cpu(sds->busiest);
5465 if (env->dst_cpu > busiest_cpu)
5468 env->imbalance = DIV_ROUND_CLOSEST(
5469 sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE);
5475 * fix_small_imbalance - Calculate the minor imbalance that exists
5476 * amongst the groups of a sched_domain, during
5478 * @env: The load balancing environment.
5479 * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
5482 void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
5484 unsigned long tmp, pwr_now = 0, pwr_move = 0;
5485 unsigned int imbn = 2;
5486 unsigned long scaled_busy_load_per_task;
5488 if (sds->this_nr_running) {
5489 sds->this_load_per_task /= sds->this_nr_running;
5490 if (sds->busiest_load_per_task >
5491 sds->this_load_per_task)
5494 sds->this_load_per_task =
5495 cpu_avg_load_per_task(env->dst_cpu);
5498 scaled_busy_load_per_task = sds->busiest_load_per_task
5499 * SCHED_POWER_SCALE;
5500 scaled_busy_load_per_task /= sds->busiest->sgp->power;
5502 if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
5503 (scaled_busy_load_per_task * imbn)) {
5504 env->imbalance = sds->busiest_load_per_task;
5509 * OK, we don't have enough imbalance to justify moving tasks,
5510 * however we may be able to increase total CPU power used by
5514 pwr_now += sds->busiest->sgp->power *
5515 min(sds->busiest_load_per_task, sds->max_load);
5516 pwr_now += sds->this->sgp->power *
5517 min(sds->this_load_per_task, sds->this_load);
5518 pwr_now /= SCHED_POWER_SCALE;
5520 /* Amount of load we'd subtract */
5521 tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
5522 sds->busiest->sgp->power;
5523 if (sds->max_load > tmp)
5524 pwr_move += sds->busiest->sgp->power *
5525 min(sds->busiest_load_per_task, sds->max_load - tmp);
5527 /* Amount of load we'd add */
5528 if (sds->max_load * sds->busiest->sgp->power <
5529 sds->busiest_load_per_task * SCHED_POWER_SCALE)
5530 tmp = (sds->max_load * sds->busiest->sgp->power) /
5531 sds->this->sgp->power;
5533 tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
5534 sds->this->sgp->power;
5535 pwr_move += sds->this->sgp->power *
5536 min(sds->this_load_per_task, sds->this_load + tmp);
5537 pwr_move /= SCHED_POWER_SCALE;
5539 /* Move if we gain throughput */
5540 if (pwr_move > pwr_now)
5541 env->imbalance = sds->busiest_load_per_task;
5545 * calculate_imbalance - Calculate the amount of imbalance present within the
5546 * groups of a given sched_domain during load balance.
5547 * @env: load balance environment
5548 * @sds: statistics of the sched_domain whose imbalance is to be calculated.
5550 static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
5552 unsigned long max_pull, load_above_capacity = ~0UL;
5554 sds->busiest_load_per_task /= sds->busiest_nr_running;
5555 if (sds->group_imb) {
5556 sds->busiest_load_per_task =
5557 min(sds->busiest_load_per_task, sds->avg_load);
5561 * In the presence of smp nice balancing, certain scenarios can have
5562 * max load less than avg load(as we skip the groups at or below
5563 * its cpu_power, while calculating max_load..)
5565 if (sds->max_load < sds->avg_load) {
5567 return fix_small_imbalance(env, sds);
5570 if (!sds->group_imb) {
5572 * Don't want to pull so many tasks that a group would go idle.
5574 load_above_capacity = (sds->busiest_nr_running -
5575 sds->busiest_group_capacity);
5577 load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
5579 load_above_capacity /= sds->busiest->sgp->power;
5583 * We're trying to get all the cpus to the average_load, so we don't
5584 * want to push ourselves above the average load, nor do we wish to
5585 * reduce the max loaded cpu below the average load. At the same time,
5586 * we also don't want to reduce the group load below the group capacity
5587 * (so that we can implement power-savings policies etc). Thus we look
5588 * for the minimum possible imbalance.
5589 * Be careful of negative numbers as they'll appear as very large values
5590 * with unsigned longs.
5592 max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);
5594 /* How much load to actually move to equalise the imbalance */
5595 env->imbalance = min(max_pull * sds->busiest->sgp->power,
5596 (sds->avg_load - sds->this_load) * sds->this->sgp->power)
5597 / SCHED_POWER_SCALE;
5600 * if *imbalance is less than the average load per runnable task
5601 * there is no guarantee that any tasks will be moved so we'll have
5602 * a think about bumping its value to force at least one task to be
5605 if (env->imbalance < sds->busiest_load_per_task)
5606 return fix_small_imbalance(env, sds);
5610 /******* find_busiest_group() helpers end here *********************/
5613 * find_busiest_group - Returns the busiest group within the sched_domain
5614 * if there is an imbalance. If there isn't an imbalance, and
5615 * the user has opted for power-savings, it returns a group whose
5616 * CPUs can be put to idle by rebalancing those tasks elsewhere, if
5617 * such a group exists.
5619 * Also calculates the amount of weighted load which should be moved
5620 * to restore balance.
5622 * @env: The load balancing environment.
5623 * @balance: Pointer to a variable indicating if this_cpu
5624 * is the appropriate cpu to perform load balancing at this_level.
5626 * Returns: - the busiest group if imbalance exists.
5627 * - If no imbalance and user has opted for power-savings balance,
5628 * return the least loaded group whose CPUs can be
5629 * put to idle by rebalancing its tasks onto our group.
5631 static struct sched_group *
5632 find_busiest_group(struct lb_env *env, int *balance)
5634 struct sd_lb_stats sds;
5636 memset(&sds, 0, sizeof(sds));
5639 * Compute the various statistics relavent for load balancing at
5642 update_sd_lb_stats(env, balance, &sds);
5645 * this_cpu is not the appropriate cpu to perform load balancing at
5651 if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) &&
5652 check_asym_packing(env, &sds))
5655 /* There is no busy sibling group to pull tasks from */
5656 if (!sds.busiest || sds.busiest_nr_running == 0)
5659 sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
5662 * If the busiest group is imbalanced the below checks don't
5663 * work because they assumes all things are equal, which typically
5664 * isn't true due to cpus_allowed constraints and the like.
5669 /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
5670 if (env->idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
5671 !sds.busiest_has_capacity)
5675 * If the local group is more busy than the selected busiest group
5676 * don't try and pull any tasks.
5678 if (sds.this_load >= sds.max_load)
5682 * Don't pull any tasks if this group is already above the domain
5685 if (sds.this_load >= sds.avg_load)
5688 if (env->idle == CPU_IDLE) {
5690 * This cpu is idle. If the busiest group load doesn't
5691 * have more tasks than the number of available cpu's and
5692 * there is no imbalance between this and busiest group
5693 * wrt to idle cpu's, it is balanced.
5695 if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) &&
5696 sds.busiest_nr_running <= sds.busiest_group_weight)
5700 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
5701 * imbalance_pct to be conservative.
5703 if (100 * sds.max_load <= env->sd->imbalance_pct * sds.this_load)
5708 /* Looks like there is an imbalance. Compute it */
5709 calculate_imbalance(env, &sds);
5719 * find_busiest_queue - find the busiest runqueue among the cpus in group.
5721 static struct rq *find_busiest_queue(struct lb_env *env,
5722 struct sched_group *group)
5724 struct rq *busiest = NULL, *rq;
5725 unsigned long max_load = 0;
5728 for_each_cpu(i, sched_group_cpus(group)) {
5729 unsigned long power = power_of(i);
5730 unsigned long capacity = DIV_ROUND_CLOSEST(power,
5735 capacity = fix_small_capacity(env->sd, group);
5737 if (!cpumask_test_cpu(i, env->cpus))
5741 wl = weighted_cpuload(i);
5744 * When comparing with imbalance, use weighted_cpuload()
5745 * which is not scaled with the cpu power.
5747 if (capacity && rq->nr_running == 1 && wl > env->imbalance)
5751 * For the load comparisons with the other cpu's, consider
5752 * the weighted_cpuload() scaled with the cpu power, so that
5753 * the load can be moved away from the cpu that is potentially
5754 * running at a lower capacity.
5756 wl = (wl * SCHED_POWER_SCALE) / power;
5758 if (wl > max_load) {
5768 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
5769 * so long as it is large enough.
5771 #define MAX_PINNED_INTERVAL 512
5773 /* Working cpumask for load_balance and load_balance_newidle. */
5774 DEFINE_PER_CPU(cpumask_var_t, load_balance_mask);
5776 static int need_active_balance(struct lb_env *env)
5778 struct sched_domain *sd = env->sd;
5780 if (env->idle == CPU_NEWLY_IDLE) {
5783 * ASYM_PACKING needs to force migrate tasks from busy but
5784 * higher numbered CPUs in order to pack all tasks in the
5785 * lowest numbered CPUs.
5787 if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu)
5791 return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
5794 static int active_load_balance_cpu_stop(void *data);
5797 * Check this_cpu to ensure it is balanced within domain. Attempt to move
5798 * tasks if there is an imbalance.
5800 static int load_balance(int this_cpu, struct rq *this_rq,
5801 struct sched_domain *sd, enum cpu_idle_type idle,
5804 int ld_moved, cur_ld_moved, active_balance = 0;
5805 struct sched_group *group;
5807 unsigned long flags;
5808 struct cpumask *cpus = __get_cpu_var(load_balance_mask);
5810 struct lb_env env = {
5812 .dst_cpu = this_cpu,
5814 .dst_grpmask = sched_group_cpus(sd->groups),
5816 .loop_break = sched_nr_migrate_break,
5821 * For NEWLY_IDLE load_balancing, we don't need to consider
5822 * other cpus in our group
5824 if (idle == CPU_NEWLY_IDLE)
5825 env.dst_grpmask = NULL;
5827 cpumask_copy(cpus, cpu_active_mask);
5829 schedstat_inc(sd, lb_count[idle]);
5832 group = find_busiest_group(&env, balance);
5838 schedstat_inc(sd, lb_nobusyg[idle]);
5842 busiest = find_busiest_queue(&env, group);
5844 schedstat_inc(sd, lb_nobusyq[idle]);
5848 BUG_ON(busiest == env.dst_rq);
5850 schedstat_add(sd, lb_imbalance[idle], env.imbalance);
5853 if (busiest->nr_running > 1) {
5855 * Attempt to move tasks. If find_busiest_group has found
5856 * an imbalance but busiest->nr_running <= 1, the group is
5857 * still unbalanced. ld_moved simply stays zero, so it is
5858 * correctly treated as an imbalance.
5860 env.flags |= LBF_ALL_PINNED;
5861 env.src_cpu = busiest->cpu;
5862 env.src_rq = busiest;
5863 env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running);
5865 update_h_load(env.src_cpu);
5867 local_irq_save(flags);
5868 double_rq_lock(env.dst_rq, busiest);
5871 * cur_ld_moved - load moved in current iteration
5872 * ld_moved - cumulative load moved across iterations
5874 cur_ld_moved = move_tasks(&env);
5875 ld_moved += cur_ld_moved;
5876 double_rq_unlock(env.dst_rq, busiest);
5877 local_irq_restore(flags);
5880 * some other cpu did the load balance for us.
5882 if (cur_ld_moved && env.dst_cpu != smp_processor_id())
5883 resched_cpu(env.dst_cpu);
5885 if (env.flags & LBF_NEED_BREAK) {
5886 env.flags &= ~LBF_NEED_BREAK;
5891 * Revisit (affine) tasks on src_cpu that couldn't be moved to
5892 * us and move them to an alternate dst_cpu in our sched_group
5893 * where they can run. The upper limit on how many times we
5894 * iterate on same src_cpu is dependent on number of cpus in our
5897 * This changes load balance semantics a bit on who can move
5898 * load to a given_cpu. In addition to the given_cpu itself
5899 * (or a ilb_cpu acting on its behalf where given_cpu is
5900 * nohz-idle), we now have balance_cpu in a position to move
5901 * load to given_cpu. In rare situations, this may cause
5902 * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
5903 * _independently_ and at _same_ time to move some load to
5904 * given_cpu) causing exceess load to be moved to given_cpu.
5905 * This however should not happen so much in practice and
5906 * moreover subsequent load balance cycles should correct the
5907 * excess load moved.
5909 if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) {
5911 env.dst_rq = cpu_rq(env.new_dst_cpu);
5912 env.dst_cpu = env.new_dst_cpu;
5913 env.flags &= ~LBF_SOME_PINNED;
5915 env.loop_break = sched_nr_migrate_break;
5917 /* Prevent to re-select dst_cpu via env's cpus */
5918 cpumask_clear_cpu(env.dst_cpu, env.cpus);
5921 * Go back to "more_balance" rather than "redo" since we
5922 * need to continue with same src_cpu.
5927 /* All tasks on this runqueue were pinned by CPU affinity */
5928 if (unlikely(env.flags & LBF_ALL_PINNED)) {
5929 cpumask_clear_cpu(cpu_of(busiest), cpus);
5930 if (!cpumask_empty(cpus)) {
5932 env.loop_break = sched_nr_migrate_break;
5940 schedstat_inc(sd, lb_failed[idle]);
5942 * Increment the failure counter only on periodic balance.
5943 * We do not want newidle balance, which can be very
5944 * frequent, pollute the failure counter causing
5945 * excessive cache_hot migrations and active balances.
5947 if (idle != CPU_NEWLY_IDLE)
5948 sd->nr_balance_failed++;
5950 if (need_active_balance(&env)) {
5951 raw_spin_lock_irqsave(&busiest->lock, flags);
5953 /* don't kick the active_load_balance_cpu_stop,
5954 * if the curr task on busiest cpu can't be
5957 if (!cpumask_test_cpu(this_cpu,
5958 tsk_cpus_allowed(busiest->curr))) {
5959 raw_spin_unlock_irqrestore(&busiest->lock,
5961 env.flags |= LBF_ALL_PINNED;
5962 goto out_one_pinned;
5966 * ->active_balance synchronizes accesses to
5967 * ->active_balance_work. Once set, it's cleared
5968 * only after active load balance is finished.
5970 if (!busiest->active_balance) {
5971 busiest->active_balance = 1;
5972 busiest->push_cpu = this_cpu;
5975 raw_spin_unlock_irqrestore(&busiest->lock, flags);
5977 if (active_balance) {
5978 stop_one_cpu_nowait(cpu_of(busiest),
5979 active_load_balance_cpu_stop, busiest,
5980 &busiest->active_balance_work);
5984 * We've kicked active balancing, reset the failure
5987 sd->nr_balance_failed = sd->cache_nice_tries+1;
5990 sd->nr_balance_failed = 0;
5992 if (likely(!active_balance)) {
5993 /* We were unbalanced, so reset the balancing interval */
5994 sd->balance_interval = sd->min_interval;
5997 * If we've begun active balancing, start to back off. This
5998 * case may not be covered by the all_pinned logic if there
5999 * is only 1 task on the busy runqueue (because we don't call
6002 if (sd->balance_interval < sd->max_interval)
6003 sd->balance_interval *= 2;
6009 schedstat_inc(sd, lb_balanced[idle]);
6011 sd->nr_balance_failed = 0;
6014 /* tune up the balancing interval */
6015 if (((env.flags & LBF_ALL_PINNED) &&
6016 sd->balance_interval < MAX_PINNED_INTERVAL) ||
6017 (sd->balance_interval < sd->max_interval))
6018 sd->balance_interval *= 2;
6024 #ifdef CONFIG_SCHED_HMP
6025 static unsigned int hmp_idle_pull(int this_cpu);
6028 * idle_balance is called by schedule() if this_cpu is about to become
6029 * idle. Attempts to pull tasks from other CPUs.
6031 void idle_balance(int this_cpu, struct rq *this_rq)
6033 struct sched_domain *sd;
6034 int pulled_task = 0;
6035 unsigned long next_balance = jiffies + HZ;
6037 this_rq->idle_stamp = this_rq->clock;
6039 if (this_rq->avg_idle < sysctl_sched_migration_cost)
6043 * Drop the rq->lock, but keep IRQ/preempt disabled.
6045 raw_spin_unlock(&this_rq->lock);
6047 update_blocked_averages(this_cpu);
6049 for_each_domain(this_cpu, sd) {
6050 unsigned long interval;
6053 if (!(sd->flags & SD_LOAD_BALANCE))
6056 if (sd->flags & SD_BALANCE_NEWIDLE) {
6057 /* If we've pulled tasks over stop searching: */
6058 pulled_task = load_balance(this_cpu, this_rq,
6059 sd, CPU_NEWLY_IDLE, &balance);
6062 interval = msecs_to_jiffies(sd->balance_interval);
6063 if (time_after(next_balance, sd->last_balance + interval))
6064 next_balance = sd->last_balance + interval;
6066 this_rq->idle_stamp = 0;
6071 #ifdef CONFIG_SCHED_HMP
6073 pulled_task = hmp_idle_pull(this_cpu);
6075 raw_spin_lock(&this_rq->lock);
6077 if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
6079 * We are going idle. next_balance may be set based on
6080 * a busy processor. So reset next_balance.
6082 this_rq->next_balance = next_balance;
6087 * active_load_balance_cpu_stop is run by cpu stopper. It pushes
6088 * running tasks off the busiest CPU onto idle CPUs. It requires at
6089 * least 1 task to be running on each physical CPU where possible, and
6090 * avoids physical / logical imbalances.
6092 static int active_load_balance_cpu_stop(void *data)
6094 struct rq *busiest_rq = data;
6095 int busiest_cpu = cpu_of(busiest_rq);
6096 int target_cpu = busiest_rq->push_cpu;
6097 struct rq *target_rq = cpu_rq(target_cpu);
6098 struct sched_domain *sd;
6100 raw_spin_lock_irq(&busiest_rq->lock);
6102 /* make sure the requested cpu hasn't gone down in the meantime */
6103 if (unlikely(busiest_cpu != smp_processor_id() ||
6104 !busiest_rq->active_balance))
6107 /* Is there any task to move? */
6108 if (busiest_rq->nr_running <= 1)
6112 * This condition is "impossible", if it occurs
6113 * we need to fix it. Originally reported by
6114 * Bjorn Helgaas on a 128-cpu setup.
6116 BUG_ON(busiest_rq == target_rq);
6118 /* move a task from busiest_rq to target_rq */
6119 double_lock_balance(busiest_rq, target_rq);
6121 /* Search for an sd spanning us and the target CPU. */
6123 for_each_domain(target_cpu, sd) {
6124 if ((sd->flags & SD_LOAD_BALANCE) &&
6125 cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
6130 struct lb_env env = {
6132 .dst_cpu = target_cpu,
6133 .dst_rq = target_rq,
6134 .src_cpu = busiest_rq->cpu,
6135 .src_rq = busiest_rq,
6139 schedstat_inc(sd, alb_count);
6141 if (move_one_task(&env))
6142 schedstat_inc(sd, alb_pushed);
6144 schedstat_inc(sd, alb_failed);
6147 double_unlock_balance(busiest_rq, target_rq);
6149 busiest_rq->active_balance = 0;
6150 raw_spin_unlock_irq(&busiest_rq->lock);
6154 #ifdef CONFIG_NO_HZ_COMMON
6156 * idle load balancing details
6157 * - When one of the busy CPUs notice that there may be an idle rebalancing
6158 * needed, they will kick the idle load balancer, which then does idle
6159 * load balancing for all the idle CPUs.
6162 cpumask_var_t idle_cpus_mask;
6164 unsigned long next_balance; /* in jiffy units */
6165 } nohz ____cacheline_aligned;
6167 static inline int find_new_ilb(int call_cpu)
6169 int ilb = cpumask_first(nohz.idle_cpus_mask);
6170 #ifdef CONFIG_SCHED_HMP
6171 /* restrict nohz balancing to occur in the same hmp domain */
6172 ilb = cpumask_first_and(nohz.idle_cpus_mask,
6173 &((struct hmp_domain *)hmp_cpu_domain(call_cpu))->cpus);
6175 if (ilb < nr_cpu_ids && idle_cpu(ilb))
6182 * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
6183 * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
6184 * CPU (if there is one).
6186 static void nohz_balancer_kick(int cpu)
6190 nohz.next_balance++;
6192 ilb_cpu = find_new_ilb(cpu);
6194 if (ilb_cpu >= nr_cpu_ids)
6197 if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu)))
6200 * Use smp_send_reschedule() instead of resched_cpu().
6201 * This way we generate a sched IPI on the target cpu which
6202 * is idle. And the softirq performing nohz idle load balance
6203 * will be run before returning from the IPI.
6205 smp_send_reschedule(ilb_cpu);
6209 static inline void nohz_balance_exit_idle(int cpu)
6211 if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
6212 cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
6213 atomic_dec(&nohz.nr_cpus);
6214 clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
6218 static inline void set_cpu_sd_state_busy(void)
6220 struct sched_domain *sd;
6221 int cpu = smp_processor_id();
6224 sd = rcu_dereference_check_sched_domain(cpu_rq(cpu)->sd);
6226 if (!sd || !sd->nohz_idle)
6230 for (; sd; sd = sd->parent)
6231 atomic_inc(&sd->groups->sgp->nr_busy_cpus);
6236 void set_cpu_sd_state_idle(void)
6238 struct sched_domain *sd;
6239 int cpu = smp_processor_id();
6242 sd = rcu_dereference_check_sched_domain(cpu_rq(cpu)->sd);
6244 if (!sd || sd->nohz_idle)
6248 for (; sd; sd = sd->parent)
6249 atomic_dec(&sd->groups->sgp->nr_busy_cpus);
6255 * This routine will record that the cpu is going idle with tick stopped.
6256 * This info will be used in performing idle load balancing in the future.
6258 void nohz_balance_enter_idle(int cpu)
6261 * If this cpu is going down, then nothing needs to be done.
6263 if (!cpu_active(cpu))
6266 if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
6269 cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
6270 atomic_inc(&nohz.nr_cpus);
6271 set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
6274 static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
6275 unsigned long action, void *hcpu)
6277 switch (action & ~CPU_TASKS_FROZEN) {
6279 nohz_balance_exit_idle(smp_processor_id());
6287 static DEFINE_SPINLOCK(balancing);
6290 * Scale the max load_balance interval with the number of CPUs in the system.
6291 * This trades load-balance latency on larger machines for less cross talk.
6293 void update_max_interval(void)
6295 max_load_balance_interval = HZ*num_online_cpus()/10;
6299 * It checks each scheduling domain to see if it is due to be balanced,
6300 * and initiates a balancing operation if so.
6302 * Balancing parameters are set up in init_sched_domains.
6304 static void rebalance_domains(int cpu, enum cpu_idle_type idle)
6307 struct rq *rq = cpu_rq(cpu);
6308 unsigned long interval;
6309 struct sched_domain *sd;
6310 /* Earliest time when we have to do rebalance again */
6311 unsigned long next_balance = jiffies + 60*HZ;
6312 int update_next_balance = 0;
6315 update_blocked_averages(cpu);
6318 for_each_domain(cpu, sd) {
6319 if (!(sd->flags & SD_LOAD_BALANCE))
6322 interval = sd->balance_interval;
6323 if (idle != CPU_IDLE)
6324 interval *= sd->busy_factor;
6326 /* scale ms to jiffies */
6327 interval = msecs_to_jiffies(interval);
6328 interval = clamp(interval, 1UL, max_load_balance_interval);
6330 need_serialize = sd->flags & SD_SERIALIZE;
6332 if (need_serialize) {
6333 if (!spin_trylock(&balancing))
6337 if (time_after_eq(jiffies, sd->last_balance + interval)) {
6338 if (load_balance(cpu, rq, sd, idle, &balance)) {
6340 * The LBF_SOME_PINNED logic could have changed
6341 * env->dst_cpu, so we can't know our idle
6342 * state even if we migrated tasks. Update it.
6344 idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE;
6346 sd->last_balance = jiffies;
6349 spin_unlock(&balancing);
6351 if (time_after(next_balance, sd->last_balance + interval)) {
6352 next_balance = sd->last_balance + interval;
6353 update_next_balance = 1;
6357 * Stop the load balance at this level. There is another
6358 * CPU in our sched group which is doing load balancing more
6367 * next_balance will be updated only when there is a need.
6368 * When the cpu is attached to null domain for ex, it will not be
6371 if (likely(update_next_balance))
6372 rq->next_balance = next_balance;
6375 #ifdef CONFIG_NO_HZ_COMMON
6377 * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
6378 * rebalancing for all the cpus for whom scheduler ticks are stopped.
6380 static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle)
6382 struct rq *this_rq = cpu_rq(this_cpu);
6386 if (idle != CPU_IDLE ||
6387 !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
6390 for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
6391 if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
6395 * If this cpu gets work to do, stop the load balancing
6396 * work being done for other cpus. Next load
6397 * balancing owner will pick it up.
6402 rq = cpu_rq(balance_cpu);
6404 raw_spin_lock_irq(&rq->lock);
6405 update_rq_clock(rq);
6406 update_idle_cpu_load(rq);
6407 raw_spin_unlock_irq(&rq->lock);
6409 rebalance_domains(balance_cpu, CPU_IDLE);
6411 if (time_after(this_rq->next_balance, rq->next_balance))
6412 this_rq->next_balance = rq->next_balance;
6414 nohz.next_balance = this_rq->next_balance;
6416 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu));
6420 * Current heuristic for kicking the idle load balancer in the presence
6421 * of an idle cpu is the system.
6422 * - This rq has more than one task.
6423 * - At any scheduler domain level, this cpu's scheduler group has multiple
6424 * busy cpu's exceeding the group's power.
6425 * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
6426 * domain span are idle.
6428 static inline int nohz_kick_needed(struct rq *rq, int cpu)
6430 unsigned long now = jiffies;
6431 struct sched_domain *sd;
6433 if (unlikely(idle_cpu(cpu)))
6437 * We may be recently in ticked or tickless idle mode. At the first
6438 * busy tick after returning from idle, we will update the busy stats.
6440 set_cpu_sd_state_busy();
6441 nohz_balance_exit_idle(cpu);
6444 * None are in tickless mode and hence no need for NOHZ idle load
6447 if (likely(!atomic_read(&nohz.nr_cpus)))
6450 if (time_before(now, nohz.next_balance))
6453 #ifdef CONFIG_SCHED_HMP
6455 * Bail out if there are no nohz CPUs in our
6456 * HMP domain, since we will move tasks between
6457 * domains through wakeup and force balancing
6458 * as necessary based upon task load.
6460 if (cpumask_first_and(nohz.idle_cpus_mask,
6461 &((struct hmp_domain *)hmp_cpu_domain(cpu))->cpus) >= nr_cpu_ids)
6465 if (rq->nr_running >= 2)
6469 for_each_domain(cpu, sd) {
6470 struct sched_group *sg = sd->groups;
6471 struct sched_group_power *sgp = sg->sgp;
6472 int nr_busy = atomic_read(&sgp->nr_busy_cpus);
6474 if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
6475 goto need_kick_unlock;
6477 if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
6478 && (cpumask_first_and(nohz.idle_cpus_mask,
6479 sched_domain_span(sd)) < cpu))
6480 goto need_kick_unlock;
6482 if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
6494 static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { }
6497 #ifdef CONFIG_SCHED_HMP
6498 /* Check if task should migrate to a faster cpu */
6499 static unsigned int hmp_up_migration(int cpu, int *target_cpu, struct sched_entity *se)
6501 struct task_struct *p = task_of(se);
6502 int temp_target_cpu;
6505 if (hmp_cpu_is_fastest(cpu))
6508 #ifdef CONFIG_SCHED_HMP_PRIO_FILTER
6509 /* Filter by task priority */
6510 if (p->prio >= hmp_up_prio)
6513 if (se->avg.load_avg_ratio < hmp_up_threshold)
6516 /* Let the task load settle before doing another up migration */
6517 /* hack - always use clock from first online CPU */
6518 now = cpu_rq(cpumask_first(cpu_online_mask))->clock_task;
6519 if (((now - se->avg.hmp_last_up_migration) >> 10)
6520 < hmp_next_up_threshold)
6523 /* hmp_domain_min_load only returns 0 for an
6524 * idle CPU or 1023 for any partly-busy one.
6525 * Be explicit about requirement for an idle CPU.
6527 if (hmp_domain_min_load(hmp_faster_domain(cpu), &temp_target_cpu,
6528 tsk_cpus_allowed(p)) == 0 && temp_target_cpu != NR_CPUS) {
6530 *target_cpu = temp_target_cpu;
6536 /* Check if task should migrate to a slower cpu */
6537 static unsigned int hmp_down_migration(int cpu, struct sched_entity *se)
6539 struct task_struct *p = task_of(se);
6542 if (hmp_cpu_is_slowest(cpu))
6545 #ifdef CONFIG_SCHED_HMP_PRIO_FILTER
6546 /* Filter by task priority */
6547 if ((p->prio >= hmp_up_prio) &&
6548 cpumask_intersects(&hmp_slower_domain(cpu)->cpus,
6549 tsk_cpus_allowed(p))) {
6554 /* Let the task load settle before doing another down migration */
6555 /* hack - always use clock from first online CPU */
6556 now = cpu_rq(cpumask_first(cpu_online_mask))->clock_task;
6557 if (((now - se->avg.hmp_last_down_migration) >> 10)
6558 < hmp_next_down_threshold)
6561 if (cpumask_intersects(&hmp_slower_domain(cpu)->cpus,
6562 tsk_cpus_allowed(p))
6563 && se->avg.load_avg_ratio < hmp_down_threshold) {
6570 * hmp_can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
6571 * Ideally this function should be merged with can_migrate_task() to avoid
6574 static int hmp_can_migrate_task(struct task_struct *p, struct lb_env *env)
6576 int tsk_cache_hot = 0;
6579 * We do not migrate tasks that are:
6580 * 1) running (obviously), or
6581 * 2) cannot be migrated to this CPU due to cpus_allowed
6583 if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
6584 schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
6587 env->flags &= ~LBF_ALL_PINNED;
6589 if (task_running(env->src_rq, p)) {
6590 schedstat_inc(p, se.statistics.nr_failed_migrations_running);
6595 * Aggressive migration if:
6596 * 1) task is cache cold, or
6597 * 2) too many balance attempts have failed.
6600 tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
6601 if (!tsk_cache_hot ||
6602 env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
6603 #ifdef CONFIG_SCHEDSTATS
6604 if (tsk_cache_hot) {
6605 schedstat_inc(env->sd, lb_hot_gained[env->idle]);
6606 schedstat_inc(p, se.statistics.nr_forced_migrations);
6616 * move_specific_task tries to move a specific task.
6617 * Returns 1 if successful and 0 otherwise.
6618 * Called with both runqueues locked.
6620 static int move_specific_task(struct lb_env *env, struct task_struct *pm)
6622 struct task_struct *p, *n;
6624 list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
6625 if (throttled_lb_pair(task_group(p), env->src_rq->cpu,
6629 if (!hmp_can_migrate_task(p, env))
6631 /* Check if we found the right task */
6637 * Right now, this is only the third place move_task()
6638 * is called, so we can safely collect move_task()
6639 * stats here rather than inside move_task().
6641 schedstat_inc(env->sd, lb_gained[env->idle]);
6648 * hmp_active_task_migration_cpu_stop is run by cpu stopper and used to
6649 * migrate a specific task from one runqueue to another.
6650 * hmp_force_up_migration uses this to push a currently running task
6652 * Based on active_load_balance_stop_cpu and can potentially be merged.
6654 static int hmp_active_task_migration_cpu_stop(void *data)
6656 struct rq *busiest_rq = data;
6657 struct task_struct *p = busiest_rq->migrate_task;
6658 int busiest_cpu = cpu_of(busiest_rq);
6659 int target_cpu = busiest_rq->push_cpu;
6660 struct rq *target_rq = cpu_rq(target_cpu);
6661 struct sched_domain *sd;
6663 raw_spin_lock_irq(&busiest_rq->lock);
6664 /* make sure the requested cpu hasn't gone down in the meantime */
6665 if (unlikely(busiest_cpu != smp_processor_id() ||
6666 !busiest_rq->active_balance)) {
6669 /* Is there any task to move? */
6670 if (busiest_rq->nr_running <= 1)
6672 /* Task has migrated meanwhile, abort forced migration */
6673 if (task_rq(p) != busiest_rq)
6676 * This condition is "impossible", if it occurs
6677 * we need to fix it. Originally reported by
6678 * Bjorn Helgaas on a 128-cpu setup.
6680 BUG_ON(busiest_rq == target_rq);
6682 /* move a task from busiest_rq to target_rq */
6683 double_lock_balance(busiest_rq, target_rq);
6685 /* Search for an sd spanning us and the target CPU. */
6687 for_each_domain(target_cpu, sd) {
6688 if (cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
6693 struct lb_env env = {
6695 .dst_cpu = target_cpu,
6696 .dst_rq = target_rq,
6697 .src_cpu = busiest_rq->cpu,
6698 .src_rq = busiest_rq,
6702 schedstat_inc(sd, alb_count);
6704 if (move_specific_task(&env, p))
6705 schedstat_inc(sd, alb_pushed);
6707 schedstat_inc(sd, alb_failed);
6710 double_unlock_balance(busiest_rq, target_rq);
6713 busiest_rq->active_balance = 0;
6714 raw_spin_unlock_irq(&busiest_rq->lock);
6719 * hmp_idle_pull_cpu_stop is run by cpu stopper and used to
6720 * migrate a specific task from one runqueue to another.
6721 * hmp_idle_pull uses this to push a currently running task
6722 * off a runqueue to a faster CPU.
6723 * Locking is slightly different than usual.
6724 * Based on active_load_balance_stop_cpu and can potentially be merged.
6726 static int hmp_idle_pull_cpu_stop(void *data)
6728 struct rq *busiest_rq = data;
6729 struct task_struct *p = busiest_rq->migrate_task;
6730 int busiest_cpu = cpu_of(busiest_rq);
6731 int target_cpu = busiest_rq->push_cpu;
6732 struct rq *target_rq = cpu_rq(target_cpu);
6733 struct sched_domain *sd;
6735 raw_spin_lock_irq(&busiest_rq->lock);
6737 /* make sure the requested cpu hasn't gone down in the meantime */
6738 if (unlikely(busiest_cpu != smp_processor_id() ||
6739 !busiest_rq->active_balance))
6742 /* Is there any task to move? */
6743 if (busiest_rq->nr_running <= 1)
6746 /* Task has migrated meanwhile, abort forced migration */
6747 if (task_rq(p) != busiest_rq)
6751 * This condition is "impossible", if it occurs
6752 * we need to fix it. Originally reported by
6753 * Bjorn Helgaas on a 128-cpu setup.
6755 BUG_ON(busiest_rq == target_rq);
6757 /* move a task from busiest_rq to target_rq */
6758 double_lock_balance(busiest_rq, target_rq);
6760 /* Search for an sd spanning us and the target CPU. */
6762 for_each_domain(target_cpu, sd) {
6763 if (cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
6767 struct lb_env env = {
6769 .dst_cpu = target_cpu,
6770 .dst_rq = target_rq,
6771 .src_cpu = busiest_rq->cpu,
6772 .src_rq = busiest_rq,
6776 schedstat_inc(sd, alb_count);
6778 if (move_specific_task(&env, p))
6779 schedstat_inc(sd, alb_pushed);
6781 schedstat_inc(sd, alb_failed);
6784 double_unlock_balance(busiest_rq, target_rq);
6787 busiest_rq->active_balance = 0;
6788 raw_spin_unlock_irq(&busiest_rq->lock);
6792 static DEFINE_SPINLOCK(hmp_force_migration);
6795 * hmp_force_up_migration checks runqueues for tasks that need to
6796 * be actively migrated to a faster cpu.
6798 static void hmp_force_up_migration(int this_cpu)
6800 int cpu, target_cpu;
6801 struct sched_entity *curr, *orig;
6803 unsigned long flags;
6805 struct task_struct *p;
6807 if (!spin_trylock(&hmp_force_migration))
6809 for_each_online_cpu(cpu) {
6811 target = cpu_rq(cpu);
6812 raw_spin_lock_irqsave(&target->lock, flags);
6813 curr = target->cfs.curr;
6815 raw_spin_unlock_irqrestore(&target->lock, flags);
6818 if (!entity_is_task(curr)) {
6819 struct cfs_rq *cfs_rq;
6821 cfs_rq = group_cfs_rq(curr);
6823 curr = cfs_rq->curr;
6824 cfs_rq = group_cfs_rq(curr);
6828 curr = hmp_get_heaviest_task(curr, 1);
6830 if (hmp_up_migration(cpu, &target_cpu, curr)) {
6831 if (!target->active_balance) {
6833 target->active_balance = 1;
6834 target->push_cpu = target_cpu;
6835 target->migrate_task = p;
6837 trace_sched_hmp_migrate(p, target->push_cpu, HMP_MIGRATE_FORCE);
6838 hmp_next_up_delay(&p->se, target->push_cpu);
6841 if (!force && !target->active_balance) {
6843 * For now we just check the currently running task.
6844 * Selecting the lightest task for offloading will
6845 * require extensive book keeping.
6847 curr = hmp_get_lightest_task(orig, 1);
6849 target->push_cpu = hmp_offload_down(cpu, curr);
6850 if (target->push_cpu < NR_CPUS) {
6852 target->active_balance = 1;
6853 target->migrate_task = p;
6855 trace_sched_hmp_migrate(p, target->push_cpu, HMP_MIGRATE_OFFLOAD);
6856 hmp_next_down_delay(&p->se, target->push_cpu);
6859 raw_spin_unlock_irqrestore(&target->lock, flags);
6861 stop_one_cpu_nowait(cpu_of(target),
6862 hmp_active_task_migration_cpu_stop,
6863 target, &target->active_balance_work);
6865 spin_unlock(&hmp_force_migration);
6868 * hmp_idle_pull looks at little domain runqueues to see
6869 * if a task should be pulled.
6871 * Reuses hmp_force_migration spinlock.
6874 static unsigned int hmp_idle_pull(int this_cpu)
6877 struct sched_entity *curr, *orig;
6878 struct hmp_domain *hmp_domain = NULL;
6879 struct rq *target, *rq;
6880 unsigned long flags, ratio = 0;
6881 unsigned int force = 0;
6882 struct task_struct *p = NULL;
6884 if (!hmp_cpu_is_slowest(this_cpu))
6885 hmp_domain = hmp_slower_domain(this_cpu);
6889 if (!spin_trylock(&hmp_force_migration))
6892 /* first select a task */
6893 for_each_cpu(cpu, &hmp_domain->cpus) {
6895 raw_spin_lock_irqsave(&rq->lock, flags);
6896 curr = rq->cfs.curr;
6898 raw_spin_unlock_irqrestore(&rq->lock, flags);
6901 if (!entity_is_task(curr)) {
6902 struct cfs_rq *cfs_rq;
6904 cfs_rq = group_cfs_rq(curr);
6906 curr = cfs_rq->curr;
6907 if (!entity_is_task(curr))
6908 cfs_rq = group_cfs_rq(curr);
6914 curr = hmp_get_heaviest_task(curr, 1);
6915 if (curr->avg.load_avg_ratio > hmp_up_threshold &&
6916 curr->avg.load_avg_ratio > ratio) {
6919 ratio = curr->avg.load_avg_ratio;
6921 raw_spin_unlock_irqrestore(&rq->lock, flags);
6927 /* now we have a candidate */
6928 raw_spin_lock_irqsave(&target->lock, flags);
6929 if (!target->active_balance && task_rq(p) == target) {
6931 target->active_balance = 1;
6932 target->push_cpu = this_cpu;
6933 target->migrate_task = p;
6935 trace_sched_hmp_migrate(p, target->push_cpu, HMP_MIGRATE_IDLE_PULL);
6936 hmp_next_up_delay(&p->se, target->push_cpu);
6938 raw_spin_unlock_irqrestore(&target->lock, flags);
6940 stop_one_cpu_nowait(cpu_of(target),
6941 hmp_idle_pull_cpu_stop,
6942 target, &target->active_balance_work);
6945 spin_unlock(&hmp_force_migration);
6949 static void hmp_force_up_migration(int this_cpu) { }
6950 #endif /* CONFIG_SCHED_HMP */
6953 * run_rebalance_domains is triggered when needed from the scheduler tick.
6954 * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
6956 static void run_rebalance_domains(struct softirq_action *h)
6958 int this_cpu = smp_processor_id();
6959 struct rq *this_rq = cpu_rq(this_cpu);
6960 enum cpu_idle_type idle = this_rq->idle_balance ?
6961 CPU_IDLE : CPU_NOT_IDLE;
6963 hmp_force_up_migration(this_cpu);
6965 rebalance_domains(this_cpu, idle);
6968 * If this cpu has a pending nohz_balance_kick, then do the
6969 * balancing on behalf of the other idle cpus whose ticks are
6972 nohz_idle_balance(this_cpu, idle);
6975 static inline int on_null_domain(int cpu)
6977 return !rcu_dereference_sched(cpu_rq(cpu)->sd);
6981 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
6983 void trigger_load_balance(struct rq *rq, int cpu)
6985 /* Don't need to rebalance while attached to NULL domain */
6986 if (time_after_eq(jiffies, rq->next_balance) &&
6987 likely(!on_null_domain(cpu)))
6988 raise_softirq(SCHED_SOFTIRQ);
6989 #ifdef CONFIG_NO_HZ_COMMON
6990 if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu)))
6991 nohz_balancer_kick(cpu);
6995 static void rq_online_fair(struct rq *rq)
6997 #ifdef CONFIG_SCHED_HMP
6998 hmp_online_cpu(rq->cpu);
7003 static void rq_offline_fair(struct rq *rq)
7005 #ifdef CONFIG_SCHED_HMP
7006 hmp_offline_cpu(rq->cpu);
7010 /* Ensure any throttled groups are reachable by pick_next_task */
7011 unthrottle_offline_cfs_rqs(rq);
7014 #endif /* CONFIG_SMP */
7017 * scheduler tick hitting a task of our scheduling class:
7019 static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
7021 struct cfs_rq *cfs_rq;
7022 struct sched_entity *se = &curr->se;
7024 for_each_sched_entity(se) {
7025 cfs_rq = cfs_rq_of(se);
7026 entity_tick(cfs_rq, se, queued);
7029 if (sched_feat_numa(NUMA))
7030 task_tick_numa(rq, curr);
7032 update_rq_runnable_avg(rq, 1);
7036 * called on fork with the child task as argument from the parent's context
7037 * - child not yet on the tasklist
7038 * - preemption disabled
7040 static void task_fork_fair(struct task_struct *p)
7042 struct cfs_rq *cfs_rq;
7043 struct sched_entity *se = &p->se, *curr;
7044 int this_cpu = smp_processor_id();
7045 struct rq *rq = this_rq();
7046 unsigned long flags;
7048 raw_spin_lock_irqsave(&rq->lock, flags);
7050 update_rq_clock(rq);
7052 cfs_rq = task_cfs_rq(current);
7053 curr = cfs_rq->curr;
7055 if (unlikely(task_cpu(p) != this_cpu)) {
7057 __set_task_cpu(p, this_cpu);
7061 update_curr(cfs_rq);
7064 se->vruntime = curr->vruntime;
7065 place_entity(cfs_rq, se, 1);
7067 if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
7069 * Upon rescheduling, sched_class::put_prev_task() will place
7070 * 'current' within the tree based on its new key value.
7072 swap(curr->vruntime, se->vruntime);
7073 resched_task(rq->curr);
7076 se->vruntime -= cfs_rq->min_vruntime;
7078 raw_spin_unlock_irqrestore(&rq->lock, flags);
7082 * Priority of the task has changed. Check to see if we preempt
7086 prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
7092 * Reschedule if we are currently running on this runqueue and
7093 * our priority decreased, or if we are not currently running on
7094 * this runqueue and our priority is higher than the current's
7096 if (rq->curr == p) {
7097 if (p->prio > oldprio)
7098 resched_task(rq->curr);
7100 check_preempt_curr(rq, p, 0);
7103 static void switched_from_fair(struct rq *rq, struct task_struct *p)
7105 struct sched_entity *se = &p->se;
7106 struct cfs_rq *cfs_rq = cfs_rq_of(se);
7109 * Ensure the task's vruntime is normalized, so that when its
7110 * switched back to the fair class the enqueue_entity(.flags=0) will
7111 * do the right thing.
7113 * If it was on_rq, then the dequeue_entity(.flags=0) will already
7114 * have normalized the vruntime, if it was !on_rq, then only when
7115 * the task is sleeping will it still have non-normalized vruntime.
7117 if (!se->on_rq && p->state != TASK_RUNNING) {
7119 * Fix up our vruntime so that the current sleep doesn't
7120 * cause 'unlimited' sleep bonus.
7122 place_entity(cfs_rq, se, 0);
7123 se->vruntime -= cfs_rq->min_vruntime;
7126 #if defined(CONFIG_FAIR_GROUP_SCHED) && defined(CONFIG_SMP)
7128 * Remove our load from contribution when we leave sched_fair
7129 * and ensure we don't carry in an old decay_count if we
7132 if (p->se.avg.decay_count) {
7133 struct cfs_rq *cfs_rq = cfs_rq_of(&p->se);
7134 __synchronize_entity_decay(&p->se);
7135 subtract_blocked_load_contrib(cfs_rq,
7136 p->se.avg.load_avg_contrib);
7142 * We switched to the sched_fair class.
7144 static void switched_to_fair(struct rq *rq, struct task_struct *p)
7150 * We were most likely switched from sched_rt, so
7151 * kick off the schedule if running, otherwise just see
7152 * if we can still preempt the current task.
7155 resched_task(rq->curr);
7157 check_preempt_curr(rq, p, 0);
7160 /* Account for a task changing its policy or group.
7162 * This routine is mostly called to set cfs_rq->curr field when a task
7163 * migrates between groups/classes.
7165 static void set_curr_task_fair(struct rq *rq)
7167 struct sched_entity *se = &rq->curr->se;
7169 for_each_sched_entity(se) {
7170 struct cfs_rq *cfs_rq = cfs_rq_of(se);
7172 set_next_entity(cfs_rq, se);
7173 /* ensure bandwidth has been allocated on our new cfs_rq */
7174 account_cfs_rq_runtime(cfs_rq, 0);
7178 void init_cfs_rq(struct cfs_rq *cfs_rq)
7180 cfs_rq->tasks_timeline = RB_ROOT;
7181 cfs_rq->min_vruntime = (u64)(-(1LL << 20));
7182 #ifndef CONFIG_64BIT
7183 cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
7185 #if defined(CONFIG_FAIR_GROUP_SCHED) && defined(CONFIG_SMP)
7186 atomic64_set(&cfs_rq->decay_counter, 1);
7187 atomic64_set(&cfs_rq->removed_load, 0);
7191 #ifdef CONFIG_FAIR_GROUP_SCHED
7192 static void task_move_group_fair(struct task_struct *p, int on_rq)
7194 struct cfs_rq *cfs_rq;
7196 * If the task was not on the rq at the time of this cgroup movement
7197 * it must have been asleep, sleeping tasks keep their ->vruntime
7198 * absolute on their old rq until wakeup (needed for the fair sleeper
7199 * bonus in place_entity()).
7201 * If it was on the rq, we've just 'preempted' it, which does convert
7202 * ->vruntime to a relative base.
7204 * Make sure both cases convert their relative position when migrating
7205 * to another cgroup's rq. This does somewhat interfere with the
7206 * fair sleeper stuff for the first placement, but who cares.
7209 * When !on_rq, vruntime of the task has usually NOT been normalized.
7210 * But there are some cases where it has already been normalized:
7212 * - Moving a forked child which is waiting for being woken up by
7213 * wake_up_new_task().
7214 * - Moving a task which has been woken up by try_to_wake_up() and
7215 * waiting for actually being woken up by sched_ttwu_pending().
7217 * To prevent boost or penalty in the new cfs_rq caused by delta
7218 * min_vruntime between the two cfs_rqs, we skip vruntime adjustment.
7220 if (!on_rq && (!p->se.sum_exec_runtime || p->state == TASK_WAKING))
7224 p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime;
7225 set_task_rq(p, task_cpu(p));
7227 cfs_rq = cfs_rq_of(&p->se);
7228 p->se.vruntime += cfs_rq->min_vruntime;
7231 * migrate_task_rq_fair() will have removed our previous
7232 * contribution, but we must synchronize for ongoing future
7235 p->se.avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
7236 cfs_rq->blocked_load_avg += p->se.avg.load_avg_contrib;
7241 void free_fair_sched_group(struct task_group *tg)
7245 destroy_cfs_bandwidth(tg_cfs_bandwidth(tg));
7247 for_each_possible_cpu(i) {
7249 kfree(tg->cfs_rq[i]);
7258 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
7260 struct cfs_rq *cfs_rq;
7261 struct sched_entity *se;
7264 tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL);
7267 tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL);
7271 tg->shares = NICE_0_LOAD;
7273 init_cfs_bandwidth(tg_cfs_bandwidth(tg));
7275 for_each_possible_cpu(i) {
7276 cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
7277 GFP_KERNEL, cpu_to_node(i));
7281 se = kzalloc_node(sizeof(struct sched_entity),
7282 GFP_KERNEL, cpu_to_node(i));
7286 init_cfs_rq(cfs_rq);
7287 init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);
7298 void unregister_fair_sched_group(struct task_group *tg, int cpu)
7300 struct rq *rq = cpu_rq(cpu);
7301 unsigned long flags;
7304 * Only empty task groups can be destroyed; so we can speculatively
7305 * check on_list without danger of it being re-added.
7307 if (!tg->cfs_rq[cpu]->on_list)
7310 raw_spin_lock_irqsave(&rq->lock, flags);
7311 list_del_leaf_cfs_rq(tg->cfs_rq[cpu]);
7312 raw_spin_unlock_irqrestore(&rq->lock, flags);
7315 void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
7316 struct sched_entity *se, int cpu,
7317 struct sched_entity *parent)
7319 struct rq *rq = cpu_rq(cpu);
7323 init_cfs_rq_runtime(cfs_rq);
7325 tg->cfs_rq[cpu] = cfs_rq;
7328 /* se could be NULL for root_task_group */
7333 se->cfs_rq = &rq->cfs;
7335 se->cfs_rq = parent->my_q;
7338 update_load_set(&se->load, 0);
7339 se->parent = parent;
7342 static DEFINE_MUTEX(shares_mutex);
7344 int sched_group_set_shares(struct task_group *tg, unsigned long shares)
7347 unsigned long flags;
7350 * We can't change the weight of the root cgroup.
7355 shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES));
7357 mutex_lock(&shares_mutex);
7358 if (tg->shares == shares)
7361 tg->shares = shares;
7362 for_each_possible_cpu(i) {
7363 struct rq *rq = cpu_rq(i);
7364 struct sched_entity *se;
7367 /* Propagate contribution to hierarchy */
7368 raw_spin_lock_irqsave(&rq->lock, flags);
7369 for_each_sched_entity(se)
7370 update_cfs_shares(group_cfs_rq(se));
7371 raw_spin_unlock_irqrestore(&rq->lock, flags);
7375 mutex_unlock(&shares_mutex);
7378 #else /* CONFIG_FAIR_GROUP_SCHED */
7380 void free_fair_sched_group(struct task_group *tg) { }
7382 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
7387 void unregister_fair_sched_group(struct task_group *tg, int cpu) { }
7389 #endif /* CONFIG_FAIR_GROUP_SCHED */
7392 static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
7394 struct sched_entity *se = &task->se;
7395 unsigned int rr_interval = 0;
7398 * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
7401 if (rq->cfs.load.weight)
7402 rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se));
7408 * All the scheduling class methods:
7410 const struct sched_class fair_sched_class = {
7411 .next = &idle_sched_class,
7412 .enqueue_task = enqueue_task_fair,
7413 .dequeue_task = dequeue_task_fair,
7414 .yield_task = yield_task_fair,
7415 .yield_to_task = yield_to_task_fair,
7417 .check_preempt_curr = check_preempt_wakeup,
7419 .pick_next_task = pick_next_task_fair,
7420 .put_prev_task = put_prev_task_fair,
7423 .select_task_rq = select_task_rq_fair,
7424 #ifdef CONFIG_FAIR_GROUP_SCHED
7425 .migrate_task_rq = migrate_task_rq_fair,
7427 .rq_online = rq_online_fair,
7428 .rq_offline = rq_offline_fair,
7430 .task_waking = task_waking_fair,
7433 .set_curr_task = set_curr_task_fair,
7434 .task_tick = task_tick_fair,
7435 .task_fork = task_fork_fair,
7437 .prio_changed = prio_changed_fair,
7438 .switched_from = switched_from_fair,
7439 .switched_to = switched_to_fair,
7441 .get_rr_interval = get_rr_interval_fair,
7443 #ifdef CONFIG_FAIR_GROUP_SCHED
7444 .task_move_group = task_move_group_fair,
7448 #ifdef CONFIG_SCHED_DEBUG
7449 void print_cfs_stats(struct seq_file *m, int cpu)
7451 struct cfs_rq *cfs_rq;
7454 for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
7455 print_cfs_rq(m, cpu, cfs_rq);
7460 __init void init_sched_fair_class(void)
7463 open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
7465 #ifdef CONFIG_NO_HZ_COMMON
7466 nohz.next_balance = jiffies;
7467 zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
7468 cpu_notifier(sched_ilb_notifier, 0);
7471 #ifdef CONFIG_SCHED_HMP
7472 hmp_cpu_mask_setup();
7478 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
7479 static u32 cpufreq_calc_scale(u32 min, u32 max, u32 curr)
7481 u32 result = curr / max;
7485 /* Called when the CPU Frequency is changed.
7486 * Once for each CPU.
7488 static int cpufreq_callback(struct notifier_block *nb,
7489 unsigned long val, void *data)
7491 struct cpufreq_freqs *freq = data;
7492 int cpu = freq->cpu;
7493 struct cpufreq_extents *extents;
7495 if (freq->flags & CPUFREQ_CONST_LOOPS)
7498 if (val != CPUFREQ_POSTCHANGE)
7501 /* if dynamic load scale is disabled, set the load scale to 1.0 */
7502 if (!hmp_data.freqinvar_load_scale_enabled) {
7503 freq_scale[cpu].curr_scale = 1024;
7507 extents = &freq_scale[cpu];
7508 if (extents->flags & SCHED_LOAD_FREQINVAR_SINGLEFREQ) {
7509 /* If our governor was recognised as a single-freq governor,
7512 extents->curr_scale = 1024;
7514 extents->curr_scale = cpufreq_calc_scale(extents->min,
7515 extents->max, freq->new);
7521 /* Called when the CPUFreq governor is changed.
7522 * Only called for the CPUs which are actually changed by the
7525 static int cpufreq_policy_callback(struct notifier_block *nb,
7526 unsigned long event, void *data)
7528 struct cpufreq_policy *policy = data;
7529 struct cpufreq_extents *extents;
7530 int cpu, singleFreq = 0;
7531 static const char performance_governor[] = "performance";
7532 static const char powersave_governor[] = "powersave";
7534 if (event == CPUFREQ_START)
7537 if (event != CPUFREQ_INCOMPATIBLE)
7540 /* CPUFreq governors do not accurately report the range of
7541 * CPU Frequencies they will choose from.
7542 * We recognise performance and powersave governors as
7543 * single-frequency only.
7545 if (!strncmp(policy->governor->name, performance_governor,
7546 strlen(performance_governor)) ||
7547 !strncmp(policy->governor->name, powersave_governor,
7548 strlen(powersave_governor)))
7551 /* Make sure that all CPUs impacted by this policy are
7552 * updated since we will only get a notification when the
7553 * user explicitly changes the policy on a CPU.
7555 for_each_cpu(cpu, policy->cpus) {
7556 extents = &freq_scale[cpu];
7557 extents->max = policy->max >> SCHED_FREQSCALE_SHIFT;
7558 extents->min = policy->min >> SCHED_FREQSCALE_SHIFT;
7559 if (!hmp_data.freqinvar_load_scale_enabled) {
7560 extents->curr_scale = 1024;
7561 } else if (singleFreq) {
7562 extents->flags |= SCHED_LOAD_FREQINVAR_SINGLEFREQ;
7563 extents->curr_scale = 1024;
7565 extents->flags &= ~SCHED_LOAD_FREQINVAR_SINGLEFREQ;
7566 extents->curr_scale = cpufreq_calc_scale(extents->min,
7567 extents->max, policy->cur);
7574 static struct notifier_block cpufreq_notifier = {
7575 .notifier_call = cpufreq_callback,
7577 static struct notifier_block cpufreq_policy_notifier = {
7578 .notifier_call = cpufreq_policy_callback,
7581 static int __init register_sched_cpufreq_notifier(void)
7585 /* init safe defaults since there are no policies at registration */
7586 for (ret = 0; ret < CONFIG_NR_CPUS; ret++) {
7588 freq_scale[ret].max = 1024;
7589 freq_scale[ret].min = 1024;
7590 freq_scale[ret].curr_scale = 1024;
7593 pr_info("sched: registering cpufreq notifiers for scale-invariant loads\n");
7594 ret = cpufreq_register_notifier(&cpufreq_policy_notifier,
7595 CPUFREQ_POLICY_NOTIFIER);
7598 ret = cpufreq_register_notifier(&cpufreq_notifier,
7599 CPUFREQ_TRANSITION_NOTIFIER);
7604 core_initcall(register_sched_cpufreq_notifier);
7605 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */