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 #include <linux/sysfs.h>
35 #include <linux/vmalloc.h>
36 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
37 /* Include cpufreq header to add a notifier so that cpu frequency
38 * scaling can track the current CPU frequency
40 #include <linux/cpufreq.h>
41 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
47 * Targeted preemption latency for CPU-bound tasks:
48 * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
50 * NOTE: this latency value is not the same as the concept of
51 * 'timeslice length' - timeslices in CFS are of variable length
52 * and have no persistent notion like in traditional, time-slice
53 * based scheduling concepts.
55 * (to see the precise effective timeslice length of your workload,
56 * run vmstat and monitor the context-switches (cs) field)
58 unsigned int sysctl_sched_latency = 6000000ULL;
59 unsigned int normalized_sysctl_sched_latency = 6000000ULL;
62 * The initial- and re-scaling of tunables is configurable
63 * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
66 * SCHED_TUNABLESCALING_NONE - unscaled, always *1
67 * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
68 * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
70 enum sched_tunable_scaling sysctl_sched_tunable_scaling
71 = SCHED_TUNABLESCALING_LOG;
74 * Minimal preemption granularity for CPU-bound tasks:
75 * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
77 unsigned int sysctl_sched_min_granularity = 750000ULL;
78 unsigned int normalized_sysctl_sched_min_granularity = 750000ULL;
81 * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
83 static unsigned int sched_nr_latency = 8;
86 * After fork, child runs first. If set to 0 (default) then
87 * parent will (try to) run first.
89 unsigned int sysctl_sched_child_runs_first __read_mostly;
92 * SCHED_OTHER wake-up granularity.
93 * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
95 * This option delays the preemption effects of decoupled workloads
96 * and reduces their over-scheduling. Synchronous workloads will still
97 * have immediate wakeup/sleep latencies.
99 unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
100 unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
102 const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
105 * The exponential sliding window over which load is averaged for shares
109 unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
111 #ifdef CONFIG_CFS_BANDWIDTH
113 * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
114 * each time a cfs_rq requests quota.
116 * Note: in the case that the slice exceeds the runtime remaining (either due
117 * to consumption or the quota being specified to be smaller than the slice)
118 * we will always only issue the remaining available time.
120 * default: 5 msec, units: microseconds
122 unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL;
126 * Increase the granularity value when there are more CPUs,
127 * because with more CPUs the 'effective latency' as visible
128 * to users decreases. But the relationship is not linear,
129 * so pick a second-best guess by going with the log2 of the
132 * This idea comes from the SD scheduler of Con Kolivas:
134 static int get_update_sysctl_factor(void)
136 unsigned int cpus = min_t(int, num_online_cpus(), 8);
139 switch (sysctl_sched_tunable_scaling) {
140 case SCHED_TUNABLESCALING_NONE:
143 case SCHED_TUNABLESCALING_LINEAR:
146 case SCHED_TUNABLESCALING_LOG:
148 factor = 1 + ilog2(cpus);
155 static void update_sysctl(void)
157 unsigned int factor = get_update_sysctl_factor();
159 #define SET_SYSCTL(name) \
160 (sysctl_##name = (factor) * normalized_sysctl_##name)
161 SET_SYSCTL(sched_min_granularity);
162 SET_SYSCTL(sched_latency);
163 SET_SYSCTL(sched_wakeup_granularity);
167 void sched_init_granularity(void)
172 #if BITS_PER_LONG == 32
173 # define WMULT_CONST (~0UL)
175 # define WMULT_CONST (1UL << 32)
178 #define WMULT_SHIFT 32
181 * Shift right and round:
183 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
186 * delta *= weight / lw
189 calc_delta_mine(unsigned long delta_exec, unsigned long weight,
190 struct load_weight *lw)
195 * weight can be less than 2^SCHED_LOAD_RESOLUTION for task group sched
196 * entities since MIN_SHARES = 2. Treat weight as 1 if less than
197 * 2^SCHED_LOAD_RESOLUTION.
199 if (likely(weight > (1UL << SCHED_LOAD_RESOLUTION)))
200 tmp = (u64)delta_exec * scale_load_down(weight);
202 tmp = (u64)delta_exec;
204 if (!lw->inv_weight) {
205 unsigned long w = scale_load_down(lw->weight);
207 if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST))
209 else if (unlikely(!w))
210 lw->inv_weight = WMULT_CONST;
212 lw->inv_weight = WMULT_CONST / w;
216 * Check whether we'd overflow the 64-bit multiplication:
218 if (unlikely(tmp > WMULT_CONST))
219 tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight,
222 tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT);
224 return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
228 const struct sched_class fair_sched_class;
230 /**************************************************************
231 * CFS operations on generic schedulable entities:
234 #ifdef CONFIG_FAIR_GROUP_SCHED
236 /* cpu runqueue to which this cfs_rq is attached */
237 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
242 /* An entity is a task if it doesn't "own" a runqueue */
243 #define entity_is_task(se) (!se->my_q)
245 static inline struct task_struct *task_of(struct sched_entity *se)
247 #ifdef CONFIG_SCHED_DEBUG
248 WARN_ON_ONCE(!entity_is_task(se));
250 return container_of(se, struct task_struct, se);
253 /* Walk up scheduling entities hierarchy */
254 #define for_each_sched_entity(se) \
255 for (; se; se = se->parent)
257 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
262 /* runqueue on which this entity is (to be) queued */
263 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
268 /* runqueue "owned" by this group */
269 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
274 static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
277 static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
279 if (!cfs_rq->on_list) {
281 * Ensure we either appear before our parent (if already
282 * enqueued) or force our parent to appear after us when it is
283 * enqueued. The fact that we always enqueue bottom-up
284 * reduces this to two cases.
286 if (cfs_rq->tg->parent &&
287 cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) {
288 list_add_rcu(&cfs_rq->leaf_cfs_rq_list,
289 &rq_of(cfs_rq)->leaf_cfs_rq_list);
291 list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
292 &rq_of(cfs_rq)->leaf_cfs_rq_list);
296 /* We should have no load, but we need to update last_decay. */
297 update_cfs_rq_blocked_load(cfs_rq, 0);
301 static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
303 if (cfs_rq->on_list) {
304 list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
309 /* Iterate thr' all leaf cfs_rq's on a runqueue */
310 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
311 list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
313 /* Do the two (enqueued) entities belong to the same group ? */
315 is_same_group(struct sched_entity *se, struct sched_entity *pse)
317 if (se->cfs_rq == pse->cfs_rq)
323 static inline struct sched_entity *parent_entity(struct sched_entity *se)
328 /* return depth at which a sched entity is present in the hierarchy */
329 static inline int depth_se(struct sched_entity *se)
333 for_each_sched_entity(se)
340 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
342 int se_depth, pse_depth;
345 * preemption test can be made between sibling entities who are in the
346 * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
347 * both tasks until we find their ancestors who are siblings of common
351 /* First walk up until both entities are at same depth */
352 se_depth = depth_se(*se);
353 pse_depth = depth_se(*pse);
355 while (se_depth > pse_depth) {
357 *se = parent_entity(*se);
360 while (pse_depth > se_depth) {
362 *pse = parent_entity(*pse);
365 while (!is_same_group(*se, *pse)) {
366 *se = parent_entity(*se);
367 *pse = parent_entity(*pse);
371 #else /* !CONFIG_FAIR_GROUP_SCHED */
373 static inline struct task_struct *task_of(struct sched_entity *se)
375 return container_of(se, struct task_struct, se);
378 static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
380 return container_of(cfs_rq, struct rq, cfs);
383 #define entity_is_task(se) 1
385 #define for_each_sched_entity(se) \
386 for (; se; se = NULL)
388 static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
390 return &task_rq(p)->cfs;
393 static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
395 struct task_struct *p = task_of(se);
396 struct rq *rq = task_rq(p);
401 /* runqueue "owned" by this group */
402 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
407 static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
411 static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
415 #define for_each_leaf_cfs_rq(rq, cfs_rq) \
416 for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
419 is_same_group(struct sched_entity *se, struct sched_entity *pse)
424 static inline struct sched_entity *parent_entity(struct sched_entity *se)
430 find_matching_se(struct sched_entity **se, struct sched_entity **pse)
434 #endif /* CONFIG_FAIR_GROUP_SCHED */
436 static __always_inline
437 void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec);
439 /**************************************************************
440 * Scheduling class tree data structure manipulation methods:
443 static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime)
445 s64 delta = (s64)(vruntime - max_vruntime);
447 max_vruntime = vruntime;
452 static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
454 s64 delta = (s64)(vruntime - min_vruntime);
456 min_vruntime = vruntime;
461 static inline int entity_before(struct sched_entity *a,
462 struct sched_entity *b)
464 return (s64)(a->vruntime - b->vruntime) < 0;
467 static void update_min_vruntime(struct cfs_rq *cfs_rq)
469 u64 vruntime = cfs_rq->min_vruntime;
472 vruntime = cfs_rq->curr->vruntime;
474 if (cfs_rq->rb_leftmost) {
475 struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost,
480 vruntime = se->vruntime;
482 vruntime = min_vruntime(vruntime, se->vruntime);
485 /* ensure we never gain time by being placed backwards. */
486 cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
489 cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
494 * Enqueue an entity into the rb-tree:
496 static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
498 struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
499 struct rb_node *parent = NULL;
500 struct sched_entity *entry;
504 * Find the right place in the rbtree:
508 entry = rb_entry(parent, struct sched_entity, run_node);
510 * We dont care about collisions. Nodes with
511 * the same key stay together.
513 if (entity_before(se, entry)) {
514 link = &parent->rb_left;
516 link = &parent->rb_right;
522 * Maintain a cache of leftmost tree entries (it is frequently
526 cfs_rq->rb_leftmost = &se->run_node;
528 rb_link_node(&se->run_node, parent, link);
529 rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
532 static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
534 if (cfs_rq->rb_leftmost == &se->run_node) {
535 struct rb_node *next_node;
537 next_node = rb_next(&se->run_node);
538 cfs_rq->rb_leftmost = next_node;
541 rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
544 struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
546 struct rb_node *left = cfs_rq->rb_leftmost;
551 return rb_entry(left, struct sched_entity, run_node);
554 static struct sched_entity *__pick_next_entity(struct sched_entity *se)
556 struct rb_node *next = rb_next(&se->run_node);
561 return rb_entry(next, struct sched_entity, run_node);
564 #ifdef CONFIG_SCHED_DEBUG
565 struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
567 struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
572 return rb_entry(last, struct sched_entity, run_node);
575 /**************************************************************
576 * Scheduling class statistics methods:
579 int sched_proc_update_handler(struct ctl_table *table, int write,
580 void __user *buffer, size_t *lenp,
583 int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
584 int factor = get_update_sysctl_factor();
589 sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
590 sysctl_sched_min_granularity);
592 #define WRT_SYSCTL(name) \
593 (normalized_sysctl_##name = sysctl_##name / (factor))
594 WRT_SYSCTL(sched_min_granularity);
595 WRT_SYSCTL(sched_latency);
596 WRT_SYSCTL(sched_wakeup_granularity);
606 static inline unsigned long
607 calc_delta_fair(unsigned long delta, struct sched_entity *se)
609 if (unlikely(se->load.weight != NICE_0_LOAD))
610 delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load);
616 * The idea is to set a period in which each task runs once.
618 * When there are too many tasks (sched_nr_latency) we have to stretch
619 * this period because otherwise the slices get too small.
621 * p = (nr <= nl) ? l : l*nr/nl
623 static u64 __sched_period(unsigned long nr_running)
625 u64 period = sysctl_sched_latency;
626 unsigned long nr_latency = sched_nr_latency;
628 if (unlikely(nr_running > nr_latency)) {
629 period = sysctl_sched_min_granularity;
630 period *= nr_running;
637 * We calculate the wall-time slice from the period by taking a part
638 * proportional to the weight.
642 static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
644 u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq);
646 for_each_sched_entity(se) {
647 struct load_weight *load;
648 struct load_weight lw;
650 cfs_rq = cfs_rq_of(se);
651 load = &cfs_rq->load;
653 if (unlikely(!se->on_rq)) {
656 update_load_add(&lw, se->load.weight);
659 slice = calc_delta_mine(slice, se->load.weight, load);
665 * We calculate the vruntime slice of a to-be-inserted task.
669 static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
671 return calc_delta_fair(sched_slice(cfs_rq, se), se);
675 * Update the current task's runtime statistics. Skip current tasks that
676 * are not in our scheduling class.
679 __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
680 unsigned long delta_exec)
682 unsigned long delta_exec_weighted;
684 schedstat_set(curr->statistics.exec_max,
685 max((u64)delta_exec, curr->statistics.exec_max));
687 curr->sum_exec_runtime += delta_exec;
688 schedstat_add(cfs_rq, exec_clock, delta_exec);
689 delta_exec_weighted = calc_delta_fair(delta_exec, curr);
691 curr->vruntime += delta_exec_weighted;
692 update_min_vruntime(cfs_rq);
695 static void update_curr(struct cfs_rq *cfs_rq)
697 struct sched_entity *curr = cfs_rq->curr;
698 u64 now = rq_of(cfs_rq)->clock_task;
699 unsigned long delta_exec;
705 * Get the amount of time the current task was running
706 * since the last time we changed load (this cannot
707 * overflow on 32 bits):
709 delta_exec = (unsigned long)(now - curr->exec_start);
713 __update_curr(cfs_rq, curr, delta_exec);
714 curr->exec_start = now;
716 if (entity_is_task(curr)) {
717 struct task_struct *curtask = task_of(curr);
719 trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
720 cpuacct_charge(curtask, delta_exec);
721 account_group_exec_runtime(curtask, delta_exec);
724 account_cfs_rq_runtime(cfs_rq, delta_exec);
728 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
730 schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock);
734 * Task is being enqueued - update stats:
736 static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
739 * Are we enqueueing a waiting task? (for current tasks
740 * a dequeue/enqueue event is a NOP)
742 if (se != cfs_rq->curr)
743 update_stats_wait_start(cfs_rq, se);
747 update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
749 schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max,
750 rq_of(cfs_rq)->clock - se->statistics.wait_start));
751 schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1);
752 schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum +
753 rq_of(cfs_rq)->clock - se->statistics.wait_start);
754 #ifdef CONFIG_SCHEDSTATS
755 if (entity_is_task(se)) {
756 trace_sched_stat_wait(task_of(se),
757 rq_of(cfs_rq)->clock - se->statistics.wait_start);
760 schedstat_set(se->statistics.wait_start, 0);
764 update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
767 * Mark the end of the wait period if dequeueing a
770 if (se != cfs_rq->curr)
771 update_stats_wait_end(cfs_rq, se);
775 * We are picking a new current task - update its stats:
778 update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
781 * We are starting a new run period:
783 se->exec_start = rq_of(cfs_rq)->clock_task;
786 /**************************************************
787 * Scheduling class queueing methods:
790 #ifdef CONFIG_NUMA_BALANCING
792 * numa task sample period in ms
794 unsigned int sysctl_numa_balancing_scan_period_min = 100;
795 unsigned int sysctl_numa_balancing_scan_period_max = 100*50;
796 unsigned int sysctl_numa_balancing_scan_period_reset = 100*600;
798 /* Portion of address space to scan in MB */
799 unsigned int sysctl_numa_balancing_scan_size = 256;
801 /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */
802 unsigned int sysctl_numa_balancing_scan_delay = 1000;
804 static void task_numa_placement(struct task_struct *p)
808 if (!p->mm) /* for example, ksmd faulting in a user's mm */
810 seq = ACCESS_ONCE(p->mm->numa_scan_seq);
811 if (p->numa_scan_seq == seq)
813 p->numa_scan_seq = seq;
815 /* FIXME: Scheduling placement policy hints go here */
819 * Got a PROT_NONE fault for a page on @node.
821 void task_numa_fault(int node, int pages, bool migrated)
823 struct task_struct *p = current;
825 if (!sched_feat_numa(NUMA))
828 /* FIXME: Allocate task-specific structure for placement policy here */
831 * If pages are properly placed (did not migrate) then scan slower.
832 * This is reset periodically in case of phase changes
835 p->numa_scan_period = min(sysctl_numa_balancing_scan_period_max,
836 p->numa_scan_period + jiffies_to_msecs(10));
838 task_numa_placement(p);
841 static void reset_ptenuma_scan(struct task_struct *p)
843 ACCESS_ONCE(p->mm->numa_scan_seq)++;
844 p->mm->numa_scan_offset = 0;
848 * The expensive part of numa migration is done from task_work context.
849 * Triggered from task_tick_numa().
851 void task_numa_work(struct callback_head *work)
853 unsigned long migrate, next_scan, now = jiffies;
854 struct task_struct *p = current;
855 struct mm_struct *mm = p->mm;
856 struct vm_area_struct *vma;
857 unsigned long start, end;
860 WARN_ON_ONCE(p != container_of(work, struct task_struct, numa_work));
862 work->next = work; /* protect against double add */
864 * Who cares about NUMA placement when they're dying.
866 * NOTE: make sure not to dereference p->mm before this check,
867 * exit_task_work() happens _after_ exit_mm() so we could be called
868 * without p->mm even though we still had it when we enqueued this
871 if (p->flags & PF_EXITING)
875 * We do not care about task placement until a task runs on a node
876 * other than the first one used by the address space. This is
877 * largely because migrations are driven by what CPU the task
878 * is running on. If it's never scheduled on another node, it'll
879 * not migrate so why bother trapping the fault.
881 if (mm->first_nid == NUMA_PTE_SCAN_INIT)
882 mm->first_nid = numa_node_id();
883 if (mm->first_nid != NUMA_PTE_SCAN_ACTIVE) {
884 /* Are we running on a new node yet? */
885 if (numa_node_id() == mm->first_nid &&
886 !sched_feat_numa(NUMA_FORCE))
889 mm->first_nid = NUMA_PTE_SCAN_ACTIVE;
893 * Reset the scan period if enough time has gone by. Objective is that
894 * scanning will be reduced if pages are properly placed. As tasks
895 * can enter different phases this needs to be re-examined. Lacking
896 * proper tracking of reference behaviour, this blunt hammer is used.
898 migrate = mm->numa_next_reset;
899 if (time_after(now, migrate)) {
900 p->numa_scan_period = sysctl_numa_balancing_scan_period_min;
901 next_scan = now + msecs_to_jiffies(sysctl_numa_balancing_scan_period_reset);
902 xchg(&mm->numa_next_reset, next_scan);
906 * Enforce maximal scan/migration frequency..
908 migrate = mm->numa_next_scan;
909 if (time_before(now, migrate))
912 if (p->numa_scan_period == 0)
913 p->numa_scan_period = sysctl_numa_balancing_scan_period_min;
915 next_scan = now + msecs_to_jiffies(p->numa_scan_period);
916 if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate)
920 * Do not set pte_numa if the current running node is rate-limited.
921 * This loses statistics on the fault but if we are unwilling to
922 * migrate to this node, it is less likely we can do useful work
924 if (migrate_ratelimited(numa_node_id()))
927 start = mm->numa_scan_offset;
928 pages = sysctl_numa_balancing_scan_size;
929 pages <<= 20 - PAGE_SHIFT; /* MB in pages */
933 down_read(&mm->mmap_sem);
934 vma = find_vma(mm, start);
936 reset_ptenuma_scan(p);
940 for (; vma; vma = vma->vm_next) {
941 if (!vma_migratable(vma))
944 /* Skip small VMAs. They are not likely to be of relevance */
945 if (vma->vm_end - vma->vm_start < HPAGE_SIZE)
949 * Skip inaccessible VMAs to avoid any confusion between
950 * PROT_NONE and NUMA hinting ptes
952 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
956 start = max(start, vma->vm_start);
957 end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE);
958 end = min(end, vma->vm_end);
959 pages -= change_prot_numa(vma, start, end);
964 } while (end != vma->vm_end);
969 * It is possible to reach the end of the VMA list but the last few VMAs are
970 * not guaranteed to the vma_migratable. If they are not, we would find the
971 * !migratable VMA on the next scan but not reset the scanner to the start
975 mm->numa_scan_offset = start;
977 reset_ptenuma_scan(p);
978 up_read(&mm->mmap_sem);
982 * Drive the periodic memory faults..
984 void task_tick_numa(struct rq *rq, struct task_struct *curr)
986 struct callback_head *work = &curr->numa_work;
990 * We don't care about NUMA placement if we don't have memory.
992 if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work)
996 * Using runtime rather than walltime has the dual advantage that
997 * we (mostly) drive the selection from busy threads and that the
998 * task needs to have done some actual work before we bother with
1001 now = curr->se.sum_exec_runtime;
1002 period = (u64)curr->numa_scan_period * NSEC_PER_MSEC;
1004 if (now - curr->node_stamp > period) {
1005 if (!curr->node_stamp)
1006 curr->numa_scan_period = sysctl_numa_balancing_scan_period_min;
1007 curr->node_stamp = now;
1009 if (!time_before(jiffies, curr->mm->numa_next_scan)) {
1010 init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */
1011 task_work_add(curr, work, true);
1016 static void task_tick_numa(struct rq *rq, struct task_struct *curr)
1019 #endif /* CONFIG_NUMA_BALANCING */
1022 account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
1024 update_load_add(&cfs_rq->load, se->load.weight);
1025 if (!parent_entity(se))
1026 update_load_add(&rq_of(cfs_rq)->load, se->load.weight);
1028 if (entity_is_task(se))
1029 list_add(&se->group_node, &rq_of(cfs_rq)->cfs_tasks);
1031 cfs_rq->nr_running++;
1035 account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
1037 update_load_sub(&cfs_rq->load, se->load.weight);
1038 if (!parent_entity(se))
1039 update_load_sub(&rq_of(cfs_rq)->load, se->load.weight);
1040 if (entity_is_task(se))
1041 list_del_init(&se->group_node);
1042 cfs_rq->nr_running--;
1045 #ifdef CONFIG_FAIR_GROUP_SCHED
1047 static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq)
1052 * Use this CPU's actual weight instead of the last load_contribution
1053 * to gain a more accurate current total weight. See
1054 * update_cfs_rq_load_contribution().
1056 tg_weight = atomic64_read(&tg->load_avg);
1057 tg_weight -= cfs_rq->tg_load_contrib;
1058 tg_weight += cfs_rq->load.weight;
1063 static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
1065 long tg_weight, load, shares;
1067 tg_weight = calc_tg_weight(tg, cfs_rq);
1068 load = cfs_rq->load.weight;
1070 shares = (tg->shares * load);
1072 shares /= tg_weight;
1074 if (shares < MIN_SHARES)
1075 shares = MIN_SHARES;
1076 if (shares > tg->shares)
1077 shares = tg->shares;
1081 # else /* CONFIG_SMP */
1082 static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
1086 # endif /* CONFIG_SMP */
1087 static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
1088 unsigned long weight)
1091 /* commit outstanding execution time */
1092 if (cfs_rq->curr == se)
1093 update_curr(cfs_rq);
1094 account_entity_dequeue(cfs_rq, se);
1097 update_load_set(&se->load, weight);
1100 account_entity_enqueue(cfs_rq, se);
1103 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
1105 static void update_cfs_shares(struct cfs_rq *cfs_rq)
1107 struct task_group *tg;
1108 struct sched_entity *se;
1112 se = tg->se[cpu_of(rq_of(cfs_rq))];
1113 if (!se || throttled_hierarchy(cfs_rq))
1116 if (likely(se->load.weight == tg->shares))
1119 shares = calc_cfs_shares(cfs_rq, tg);
1121 reweight_entity(cfs_rq_of(se), se, shares);
1123 #else /* CONFIG_FAIR_GROUP_SCHED */
1124 static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
1127 #endif /* CONFIG_FAIR_GROUP_SCHED */
1129 /* Only depends on SMP, FAIR_GROUP_SCHED may be removed when useful in lb */
1130 #if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
1132 * We choose a half-life close to 1 scheduling period.
1133 * Note: The tables below are dependent on this value.
1135 #define LOAD_AVG_PERIOD 32
1136 #define LOAD_AVG_MAX 47742 /* maximum possible load avg */
1137 #define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_MAX_AVG */
1139 /* Precomputed fixed inverse multiplies for multiplication by y^n */
1140 static const u32 runnable_avg_yN_inv[] = {
1141 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6,
1142 0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85,
1143 0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581,
1144 0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9,
1145 0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80,
1146 0x85aac367, 0x82cd8698,
1150 * Precomputed \Sum y^k { 1<=k<=n }. These are floor(true_value) to prevent
1151 * over-estimates when re-combining.
1153 static const u32 runnable_avg_yN_sum[] = {
1154 0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103,
1155 9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082,
1156 17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371,
1161 * val * y^n, where y^32 ~= 0.5 (~1 scheduling period)
1163 static __always_inline u64 decay_load(u64 val, u64 n)
1165 unsigned int local_n;
1169 else if (unlikely(n > LOAD_AVG_PERIOD * 63))
1172 /* after bounds checking we can collapse to 32-bit */
1176 * As y^PERIOD = 1/2, we can combine
1177 * y^n = 1/2^(n/PERIOD) * k^(n%PERIOD)
1178 * With a look-up table which covers k^n (n<PERIOD)
1180 * To achieve constant time decay_load.
1182 if (unlikely(local_n >= LOAD_AVG_PERIOD)) {
1183 val >>= local_n / LOAD_AVG_PERIOD;
1184 local_n %= LOAD_AVG_PERIOD;
1187 val *= runnable_avg_yN_inv[local_n];
1188 /* We don't use SRR here since we always want to round down. */
1193 * For updates fully spanning n periods, the contribution to runnable
1194 * average will be: \Sum 1024*y^n
1196 * We can compute this reasonably efficiently by combining:
1197 * y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for n <PERIOD}
1199 static u32 __compute_runnable_contrib(u64 n)
1203 if (likely(n <= LOAD_AVG_PERIOD))
1204 return runnable_avg_yN_sum[n];
1205 else if (unlikely(n >= LOAD_AVG_MAX_N))
1206 return LOAD_AVG_MAX;
1208 /* Compute \Sum k^n combining precomputed values for k^i, \Sum k^j */
1210 contrib /= 2; /* y^LOAD_AVG_PERIOD = 1/2 */
1211 contrib += runnable_avg_yN_sum[LOAD_AVG_PERIOD];
1213 n -= LOAD_AVG_PERIOD;
1214 } while (n > LOAD_AVG_PERIOD);
1216 contrib = decay_load(contrib, n);
1217 return contrib + runnable_avg_yN_sum[n];
1220 #ifdef CONFIG_SCHED_HMP
1221 #define HMP_VARIABLE_SCALE_SHIFT 16ULL
1222 struct hmp_global_attr {
1223 struct attribute attr;
1224 ssize_t (*show)(struct kobject *kobj,
1225 struct attribute *attr, char *buf);
1226 ssize_t (*store)(struct kobject *a, struct attribute *b,
1227 const char *c, size_t count);
1229 int (*to_sysfs)(int);
1230 int (*from_sysfs)(int);
1231 ssize_t (*to_sysfs_text)(char *buf, int buf_size);
1234 #define HMP_DATA_SYSFS_MAX 8
1236 struct hmp_data_struct {
1237 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1238 int freqinvar_load_scale_enabled;
1240 int multiplier; /* used to scale the time delta */
1241 struct attribute_group attr_group;
1242 struct attribute *attributes[HMP_DATA_SYSFS_MAX + 1];
1243 struct hmp_global_attr attr[HMP_DATA_SYSFS_MAX];
1246 static u64 hmp_variable_scale_convert(u64 delta);
1247 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1248 /* Frequency-Invariant Load Modification:
1249 * Loads are calculated as in PJT's patch however we also scale the current
1250 * contribution in line with the frequency of the CPU that the task was
1252 * In this version, we use a simple linear scale derived from the maximum
1253 * frequency reported by CPUFreq. As an example:
1255 * Consider that we ran a task for 100% of the previous interval.
1257 * Our CPU was under asynchronous frequency control through one of the
1258 * CPUFreq governors.
1260 * The CPUFreq governor reports that it is able to scale the CPU between
1263 * During the period, the CPU was running at 1GHz.
1265 * In this case, our load contribution for that period is calculated as
1266 * 1 * (number_of_active_microseconds)
1268 * This results in our task being able to accumulate maximum load as normal.
1271 * Consider now that our CPU was executing at 500MHz.
1273 * We now scale the load contribution such that it is calculated as
1274 * 0.5 * (number_of_active_microseconds)
1276 * Our task can only record 50% maximum load during this period.
1278 * This represents the task consuming 50% of the CPU's *possible* compute
1279 * capacity. However the task did consume 100% of the CPU's *available*
1280 * compute capacity which is the value seen by the CPUFreq governor and
1281 * user-side CPU Utilization tools.
1283 * Restricting tracked load to be scaled by the CPU's frequency accurately
1284 * represents the consumption of possible compute capacity and allows the
1285 * HMP migration's simple threshold migration strategy to interact more
1286 * predictably with CPUFreq's asynchronous compute capacity changes.
1288 #define SCHED_FREQSCALE_SHIFT 10
1289 struct cpufreq_extents {
1295 /* Flag set when the governor in use only allows one frequency.
1298 #define SCHED_LOAD_FREQINVAR_SINGLEFREQ 0x01
1300 static struct cpufreq_extents freq_scale[CONFIG_NR_CPUS];
1301 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1302 #endif /* CONFIG_SCHED_HMP */
1304 /* We can represent the historical contribution to runnable average as the
1305 * coefficients of a geometric series. To do this we sub-divide our runnable
1306 * history into segments of approximately 1ms (1024us); label the segment that
1307 * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g.
1309 * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ...
1311 * (now) (~1ms ago) (~2ms ago)
1313 * Let u_i denote the fraction of p_i that the entity was runnable.
1315 * We then designate the fractions u_i as our co-efficients, yielding the
1316 * following representation of historical load:
1317 * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ...
1319 * We choose y based on the with of a reasonably scheduling period, fixing:
1322 * This means that the contribution to load ~32ms ago (u_32) will be weighted
1323 * approximately half as much as the contribution to load within the last ms
1326 * When a period "rolls over" and we have new u_0`, multiplying the previous
1327 * sum again by y is sufficient to update:
1328 * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... )
1329 * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
1331 static __always_inline int __update_entity_runnable_avg(u64 now,
1332 struct sched_avg *sa,
1338 u32 runnable_contrib;
1339 int delta_w, decayed = 0;
1340 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1342 u32 scaled_runnable_contrib;
1344 u32 curr_scale = 1024;
1345 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1347 delta = now - sa->last_runnable_update;
1348 #ifdef CONFIG_SCHED_HMP
1349 delta = hmp_variable_scale_convert(delta);
1352 * This should only happen when time goes backwards, which it
1353 * unfortunately does during sched clock init when we swap over to TSC.
1355 if ((s64)delta < 0) {
1356 sa->last_runnable_update = now;
1361 * Use 1024ns as the unit of measurement since it's a reasonable
1362 * approximation of 1us and fast to compute.
1367 sa->last_runnable_update = now;
1369 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1370 /* retrieve scale factor for load */
1371 if (hmp_data.freqinvar_load_scale_enabled)
1372 curr_scale = freq_scale[cpu].curr_scale;
1373 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1375 /* delta_w is the amount already accumulated against our next period */
1376 delta_w = sa->runnable_avg_period % 1024;
1377 if (delta + delta_w >= 1024) {
1378 /* period roll-over */
1382 * Now that we know we're crossing a period boundary, figure
1383 * out how much from delta we need to complete the current
1384 * period and accrue it.
1386 delta_w = 1024 - delta_w;
1387 /* scale runnable time if necessary */
1388 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1389 scaled_delta_w = (delta_w * curr_scale)
1390 >> SCHED_FREQSCALE_SHIFT;
1392 sa->runnable_avg_sum += scaled_delta_w;
1394 sa->usage_avg_sum += scaled_delta_w;
1397 sa->runnable_avg_sum += delta_w;
1399 sa->usage_avg_sum += delta_w;
1400 #endif /* #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1401 sa->runnable_avg_period += delta_w;
1405 /* Figure out how many additional periods this update spans */
1406 periods = delta / 1024;
1408 /* decay the load we have accumulated so far */
1409 sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum,
1411 sa->runnable_avg_period = decay_load(sa->runnable_avg_period,
1413 sa->usage_avg_sum = decay_load(sa->usage_avg_sum, periods + 1);
1414 /* add the contribution from this period */
1415 /* Efficiently calculate \sum (1..n_period) 1024*y^i */
1416 runnable_contrib = __compute_runnable_contrib(periods);
1417 /* Apply load scaling if necessary.
1418 * Note that multiplying the whole series is same as
1419 * multiplying all terms
1421 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1422 scaled_runnable_contrib = (runnable_contrib * curr_scale)
1423 >> SCHED_FREQSCALE_SHIFT;
1425 sa->runnable_avg_sum += scaled_runnable_contrib;
1427 sa->usage_avg_sum += scaled_runnable_contrib;
1430 sa->runnable_avg_sum += runnable_contrib;
1432 sa->usage_avg_sum += runnable_contrib;
1433 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1434 sa->runnable_avg_period += runnable_contrib;
1437 /* Remainder of delta accrued against u_0` */
1438 /* scale if necessary */
1439 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1440 scaled_delta = ((delta * curr_scale) >> SCHED_FREQSCALE_SHIFT);
1442 sa->runnable_avg_sum += scaled_delta;
1444 sa->usage_avg_sum += scaled_delta;
1447 sa->runnable_avg_sum += delta;
1449 sa->usage_avg_sum += delta;
1450 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */
1451 sa->runnable_avg_period += delta;
1456 /* Synchronize an entity's decay with its parenting cfs_rq.*/
1457 static inline u64 __synchronize_entity_decay(struct sched_entity *se)
1459 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1460 u64 decays = atomic64_read(&cfs_rq->decay_counter);
1462 decays -= se->avg.decay_count;
1464 se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays);
1465 se->avg.decay_count = 0;
1469 #ifdef CONFIG_FAIR_GROUP_SCHED
1470 static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
1473 struct task_group *tg = cfs_rq->tg;
1476 tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg;
1477 tg_contrib -= cfs_rq->tg_load_contrib;
1479 if (force_update || abs64(tg_contrib) > cfs_rq->tg_load_contrib / 8) {
1480 atomic64_add(tg_contrib, &tg->load_avg);
1481 cfs_rq->tg_load_contrib += tg_contrib;
1486 * Aggregate cfs_rq runnable averages into an equivalent task_group
1487 * representation for computing load contributions.
1489 static inline void __update_tg_runnable_avg(struct sched_avg *sa,
1490 struct cfs_rq *cfs_rq)
1492 struct task_group *tg = cfs_rq->tg;
1493 long contrib, usage_contrib;
1495 /* The fraction of a cpu used by this cfs_rq */
1496 contrib = div_u64(sa->runnable_avg_sum << NICE_0_SHIFT,
1497 sa->runnable_avg_period + 1);
1498 contrib -= cfs_rq->tg_runnable_contrib;
1500 usage_contrib = div_u64(sa->usage_avg_sum << NICE_0_SHIFT,
1501 sa->runnable_avg_period + 1);
1502 usage_contrib -= cfs_rq->tg_usage_contrib;
1505 * contrib/usage at this point represent deltas, only update if they
1508 if ((abs(contrib) > cfs_rq->tg_runnable_contrib / 64) ||
1509 (abs(usage_contrib) > cfs_rq->tg_usage_contrib / 64)) {
1510 atomic_add(contrib, &tg->runnable_avg);
1511 cfs_rq->tg_runnable_contrib += contrib;
1513 atomic_add(usage_contrib, &tg->usage_avg);
1514 cfs_rq->tg_usage_contrib += usage_contrib;
1518 static inline void __update_group_entity_contrib(struct sched_entity *se)
1520 struct cfs_rq *cfs_rq = group_cfs_rq(se);
1521 struct task_group *tg = cfs_rq->tg;
1526 contrib = cfs_rq->tg_load_contrib * tg->shares;
1527 se->avg.load_avg_contrib = div64_u64(contrib,
1528 atomic64_read(&tg->load_avg) + 1);
1531 * For group entities we need to compute a correction term in the case
1532 * that they are consuming <1 cpu so that we would contribute the same
1533 * load as a task of equal weight.
1535 * Explicitly co-ordinating this measurement would be expensive, but
1536 * fortunately the sum of each cpus contribution forms a usable
1537 * lower-bound on the true value.
1539 * Consider the aggregate of 2 contributions. Either they are disjoint
1540 * (and the sum represents true value) or they are disjoint and we are
1541 * understating by the aggregate of their overlap.
1543 * Extending this to N cpus, for a given overlap, the maximum amount we
1544 * understand is then n_i(n_i+1)/2 * w_i where n_i is the number of
1545 * cpus that overlap for this interval and w_i is the interval width.
1547 * On a small machine; the first term is well-bounded which bounds the
1548 * total error since w_i is a subset of the period. Whereas on a
1549 * larger machine, while this first term can be larger, if w_i is the
1550 * of consequential size guaranteed to see n_i*w_i quickly converge to
1551 * our upper bound of 1-cpu.
1553 runnable_avg = atomic_read(&tg->runnable_avg);
1554 if (runnable_avg < NICE_0_LOAD) {
1555 se->avg.load_avg_contrib *= runnable_avg;
1556 se->avg.load_avg_contrib >>= NICE_0_SHIFT;
1560 static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
1561 int force_update) {}
1562 static inline void __update_tg_runnable_avg(struct sched_avg *sa,
1563 struct cfs_rq *cfs_rq) {}
1564 static inline void __update_group_entity_contrib(struct sched_entity *se) {}
1567 static inline void __update_task_entity_contrib(struct sched_entity *se)
1571 /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
1572 contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);
1573 contrib /= (se->avg.runnable_avg_period + 1);
1574 se->avg.load_avg_contrib = scale_load(contrib);
1575 trace_sched_task_load_contrib(task_of(se), se->avg.load_avg_contrib);
1576 contrib = se->avg.runnable_avg_sum * scale_load_down(NICE_0_LOAD);
1577 contrib /= (se->avg.runnable_avg_period + 1);
1578 se->avg.load_avg_ratio = scale_load(contrib);
1579 trace_sched_task_runnable_ratio(task_of(se), se->avg.load_avg_ratio);
1582 /* Compute the current contribution to load_avg by se, return any delta */
1583 static long __update_entity_load_avg_contrib(struct sched_entity *se, long *ratio)
1585 long old_contrib = se->avg.load_avg_contrib;
1586 long old_ratio = se->avg.load_avg_ratio;
1588 if (entity_is_task(se)) {
1589 __update_task_entity_contrib(se);
1591 __update_tg_runnable_avg(&se->avg, group_cfs_rq(se));
1592 __update_group_entity_contrib(se);
1596 *ratio = se->avg.load_avg_ratio - old_ratio;
1597 return se->avg.load_avg_contrib - old_contrib;
1600 static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq,
1603 if (likely(load_contrib < cfs_rq->blocked_load_avg))
1604 cfs_rq->blocked_load_avg -= load_contrib;
1606 cfs_rq->blocked_load_avg = 0;
1609 static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq);
1611 /* Update a sched_entity's runnable average */
1612 static inline void update_entity_load_avg(struct sched_entity *se,
1615 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1616 long contrib_delta, ratio_delta;
1618 int cpu = -1; /* not used in normal case */
1620 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1621 cpu = cfs_rq->rq->cpu;
1624 * For a group entity we need to use their owned cfs_rq_clock_task() in
1625 * case they are the parent of a throttled hierarchy.
1627 if (entity_is_task(se))
1628 now = cfs_rq_clock_task(cfs_rq);
1630 now = cfs_rq_clock_task(group_cfs_rq(se));
1632 if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq,
1633 cfs_rq->curr == se, cpu))
1636 contrib_delta = __update_entity_load_avg_contrib(se, &ratio_delta);
1642 cfs_rq->runnable_load_avg += contrib_delta;
1643 rq_of(cfs_rq)->avg.load_avg_ratio += ratio_delta;
1645 subtract_blocked_load_contrib(cfs_rq, -contrib_delta);
1650 * Decay the load contributed by all blocked children and account this so that
1651 * their contribution may appropriately discounted when they wake up.
1653 static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update)
1655 u64 now = cfs_rq_clock_task(cfs_rq) >> 20;
1658 decays = now - cfs_rq->last_decay;
1659 if (!decays && !force_update)
1662 if (atomic64_read(&cfs_rq->removed_load)) {
1663 u64 removed_load = atomic64_xchg(&cfs_rq->removed_load, 0);
1664 subtract_blocked_load_contrib(cfs_rq, removed_load);
1668 cfs_rq->blocked_load_avg = decay_load(cfs_rq->blocked_load_avg,
1670 atomic64_add(decays, &cfs_rq->decay_counter);
1671 cfs_rq->last_decay = now;
1674 __update_cfs_rq_tg_load_contrib(cfs_rq, force_update);
1677 static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
1679 int cpu = -1; /* not used in normal case */
1681 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
1684 __update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable,
1686 __update_tg_runnable_avg(&rq->avg, &rq->cfs);
1687 trace_sched_rq_runnable_ratio(cpu_of(rq), rq->avg.load_avg_ratio);
1688 trace_sched_rq_runnable_load(cpu_of(rq), rq->cfs.runnable_load_avg);
1689 trace_sched_rq_nr_running(cpu_of(rq), rq->nr_running, rq->nr_iowait.counter);
1692 /* Add the load generated by se into cfs_rq's child load-average */
1693 static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
1694 struct sched_entity *se,
1698 * We track migrations using entity decay_count <= 0, on a wake-up
1699 * migration we use a negative decay count to track the remote decays
1700 * accumulated while sleeping.
1702 if (unlikely(se->avg.decay_count <= 0)) {
1703 se->avg.last_runnable_update = rq_of(cfs_rq)->clock_task;
1704 if (se->avg.decay_count) {
1706 * In a wake-up migration we have to approximate the
1707 * time sleeping. This is because we can't synchronize
1708 * clock_task between the two cpus, and it is not
1709 * guaranteed to be read-safe. Instead, we can
1710 * approximate this using our carried decays, which are
1711 * explicitly atomically readable.
1713 se->avg.last_runnable_update -= (-se->avg.decay_count)
1715 update_entity_load_avg(se, 0);
1716 /* Indicate that we're now synchronized and on-rq */
1717 se->avg.decay_count = 0;
1721 __synchronize_entity_decay(se);
1724 /* migrated tasks did not contribute to our blocked load */
1726 subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib);
1727 update_entity_load_avg(se, 0);
1730 cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
1731 rq_of(cfs_rq)->avg.load_avg_ratio += se->avg.load_avg_ratio;
1733 /* we force update consideration on load-balancer moves */
1734 update_cfs_rq_blocked_load(cfs_rq, !wakeup);
1738 * Remove se's load from this cfs_rq child load-average, if the entity is
1739 * transitioning to a blocked state we track its projected decay using
1742 static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
1743 struct sched_entity *se,
1746 update_entity_load_avg(se, 1);
1747 /* we force update consideration on load-balancer moves */
1748 update_cfs_rq_blocked_load(cfs_rq, !sleep);
1750 cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib;
1751 rq_of(cfs_rq)->avg.load_avg_ratio -= se->avg.load_avg_ratio;
1754 cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
1755 se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
1756 } /* migrations, e.g. sleep=0 leave decay_count == 0 */
1760 * Update the rq's load with the elapsed running time before entering
1761 * idle. if the last scheduled task is not a CFS task, idle_enter will
1762 * be the only way to update the runnable statistic.
1764 void idle_enter_fair(struct rq *this_rq)
1766 update_rq_runnable_avg(this_rq, 1);
1770 * Update the rq's load with the elapsed idle time before a task is
1771 * scheduled. if the newly scheduled task is not a CFS task, idle_exit will
1772 * be the only way to update the runnable statistic.
1774 void idle_exit_fair(struct rq *this_rq)
1776 update_rq_runnable_avg(this_rq, 0);
1780 static inline void update_entity_load_avg(struct sched_entity *se,
1781 int update_cfs_rq) {}
1782 static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
1783 static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
1784 struct sched_entity *se,
1786 static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
1787 struct sched_entity *se,
1789 static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
1790 int force_update) {}
1793 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
1795 #ifdef CONFIG_SCHEDSTATS
1796 struct task_struct *tsk = NULL;
1798 if (entity_is_task(se))
1801 if (se->statistics.sleep_start) {
1802 u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start;
1807 if (unlikely(delta > se->statistics.sleep_max))
1808 se->statistics.sleep_max = delta;
1810 se->statistics.sleep_start = 0;
1811 se->statistics.sum_sleep_runtime += delta;
1814 account_scheduler_latency(tsk, delta >> 10, 1);
1815 trace_sched_stat_sleep(tsk, delta);
1818 if (se->statistics.block_start) {
1819 u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start;
1824 if (unlikely(delta > se->statistics.block_max))
1825 se->statistics.block_max = delta;
1827 se->statistics.block_start = 0;
1828 se->statistics.sum_sleep_runtime += delta;
1831 if (tsk->in_iowait) {
1832 se->statistics.iowait_sum += delta;
1833 se->statistics.iowait_count++;
1834 trace_sched_stat_iowait(tsk, delta);
1837 trace_sched_stat_blocked(tsk, delta);
1840 * Blocking time is in units of nanosecs, so shift by
1841 * 20 to get a milliseconds-range estimation of the
1842 * amount of time that the task spent sleeping:
1844 if (unlikely(prof_on == SLEEP_PROFILING)) {
1845 profile_hits(SLEEP_PROFILING,
1846 (void *)get_wchan(tsk),
1849 account_scheduler_latency(tsk, delta >> 10, 0);
1855 static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
1857 #ifdef CONFIG_SCHED_DEBUG
1858 s64 d = se->vruntime - cfs_rq->min_vruntime;
1863 if (d > 3*sysctl_sched_latency)
1864 schedstat_inc(cfs_rq, nr_spread_over);
1869 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
1871 u64 vruntime = cfs_rq->min_vruntime;
1874 * The 'current' period is already promised to the current tasks,
1875 * however the extra weight of the new task will slow them down a
1876 * little, place the new task so that it fits in the slot that
1877 * stays open at the end.
1879 if (initial && sched_feat(START_DEBIT))
1880 vruntime += sched_vslice(cfs_rq, se);
1882 /* sleeps up to a single latency don't count. */
1884 unsigned long thresh = sysctl_sched_latency;
1887 * Halve their sleep time's effect, to allow
1888 * for a gentler effect of sleepers:
1890 if (sched_feat(GENTLE_FAIR_SLEEPERS))
1896 /* ensure we never gain time by being placed backwards. */
1897 se->vruntime = max_vruntime(se->vruntime, vruntime);
1900 static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
1903 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1906 * Update the normalized vruntime before updating min_vruntime
1907 * through callig update_curr().
1909 if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING))
1910 se->vruntime += cfs_rq->min_vruntime;
1913 * Update run-time statistics of the 'current'.
1915 update_curr(cfs_rq);
1916 enqueue_entity_load_avg(cfs_rq, se, flags & ENQUEUE_WAKEUP);
1917 account_entity_enqueue(cfs_rq, se);
1918 update_cfs_shares(cfs_rq);
1920 if (flags & ENQUEUE_WAKEUP) {
1921 place_entity(cfs_rq, se, 0);
1922 enqueue_sleeper(cfs_rq, se);
1925 update_stats_enqueue(cfs_rq, se);
1926 check_spread(cfs_rq, se);
1927 if (se != cfs_rq->curr)
1928 __enqueue_entity(cfs_rq, se);
1931 if (cfs_rq->nr_running == 1) {
1932 list_add_leaf_cfs_rq(cfs_rq);
1933 check_enqueue_throttle(cfs_rq);
1937 static void __clear_buddies_last(struct sched_entity *se)
1939 for_each_sched_entity(se) {
1940 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1941 if (cfs_rq->last == se)
1942 cfs_rq->last = NULL;
1948 static void __clear_buddies_next(struct sched_entity *se)
1950 for_each_sched_entity(se) {
1951 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1952 if (cfs_rq->next == se)
1953 cfs_rq->next = NULL;
1959 static void __clear_buddies_skip(struct sched_entity *se)
1961 for_each_sched_entity(se) {
1962 struct cfs_rq *cfs_rq = cfs_rq_of(se);
1963 if (cfs_rq->skip == se)
1964 cfs_rq->skip = NULL;
1970 static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
1972 if (cfs_rq->last == se)
1973 __clear_buddies_last(se);
1975 if (cfs_rq->next == se)
1976 __clear_buddies_next(se);
1978 if (cfs_rq->skip == se)
1979 __clear_buddies_skip(se);
1982 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
1985 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1988 * Update run-time statistics of the 'current'.
1990 update_curr(cfs_rq);
1991 dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP);
1993 update_stats_dequeue(cfs_rq, se);
1994 if (flags & DEQUEUE_SLEEP) {
1995 #ifdef CONFIG_SCHEDSTATS
1996 if (entity_is_task(se)) {
1997 struct task_struct *tsk = task_of(se);
1999 if (tsk->state & TASK_INTERRUPTIBLE)
2000 se->statistics.sleep_start = rq_of(cfs_rq)->clock;
2001 if (tsk->state & TASK_UNINTERRUPTIBLE)
2002 se->statistics.block_start = rq_of(cfs_rq)->clock;
2007 clear_buddies(cfs_rq, se);
2009 if (se != cfs_rq->curr)
2010 __dequeue_entity(cfs_rq, se);
2012 account_entity_dequeue(cfs_rq, se);
2015 * Normalize the entity after updating the min_vruntime because the
2016 * update can refer to the ->curr item and we need to reflect this
2017 * movement in our normalized position.
2019 if (!(flags & DEQUEUE_SLEEP))
2020 se->vruntime -= cfs_rq->min_vruntime;
2022 /* return excess runtime on last dequeue */
2023 return_cfs_rq_runtime(cfs_rq);
2025 update_min_vruntime(cfs_rq);
2026 update_cfs_shares(cfs_rq);
2030 * Preempt the current task with a newly woken task if needed:
2033 check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
2035 unsigned long ideal_runtime, delta_exec;
2036 struct sched_entity *se;
2039 ideal_runtime = sched_slice(cfs_rq, curr);
2040 delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
2041 if (delta_exec > ideal_runtime) {
2042 resched_task(rq_of(cfs_rq)->curr);
2044 * The current task ran long enough, ensure it doesn't get
2045 * re-elected due to buddy favours.
2047 clear_buddies(cfs_rq, curr);
2052 * Ensure that a task that missed wakeup preemption by a
2053 * narrow margin doesn't have to wait for a full slice.
2054 * This also mitigates buddy induced latencies under load.
2056 if (delta_exec < sysctl_sched_min_granularity)
2059 se = __pick_first_entity(cfs_rq);
2060 delta = curr->vruntime - se->vruntime;
2065 if (delta > ideal_runtime)
2066 resched_task(rq_of(cfs_rq)->curr);
2070 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
2072 /* 'current' is not kept within the tree. */
2075 * Any task has to be enqueued before it get to execute on
2076 * a CPU. So account for the time it spent waiting on the
2079 update_stats_wait_end(cfs_rq, se);
2080 __dequeue_entity(cfs_rq, se);
2081 update_entity_load_avg(se, 1);
2084 update_stats_curr_start(cfs_rq, se);
2086 #ifdef CONFIG_SCHEDSTATS
2088 * Track our maximum slice length, if the CPU's load is at
2089 * least twice that of our own weight (i.e. dont track it
2090 * when there are only lesser-weight tasks around):
2092 if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
2093 se->statistics.slice_max = max(se->statistics.slice_max,
2094 se->sum_exec_runtime - se->prev_sum_exec_runtime);
2097 se->prev_sum_exec_runtime = se->sum_exec_runtime;
2101 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
2104 * Pick the next process, keeping these things in mind, in this order:
2105 * 1) keep things fair between processes/task groups
2106 * 2) pick the "next" process, since someone really wants that to run
2107 * 3) pick the "last" process, for cache locality
2108 * 4) do not run the "skip" process, if something else is available
2110 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
2112 struct sched_entity *se = __pick_first_entity(cfs_rq);
2113 struct sched_entity *left = se;
2116 * Avoid running the skip buddy, if running something else can
2117 * be done without getting too unfair.
2119 if (cfs_rq->skip == se) {
2120 struct sched_entity *second = __pick_next_entity(se);
2121 if (second && wakeup_preempt_entity(second, left) < 1)
2126 * Prefer last buddy, try to return the CPU to a preempted task.
2128 if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
2132 * Someone really wants this to run. If it's not unfair, run it.
2134 if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
2137 clear_buddies(cfs_rq, se);
2142 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
2144 static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
2147 * If still on the runqueue then deactivate_task()
2148 * was not called and update_curr() has to be done:
2151 update_curr(cfs_rq);
2153 /* throttle cfs_rqs exceeding runtime */
2154 check_cfs_rq_runtime(cfs_rq);
2156 check_spread(cfs_rq, prev);
2158 update_stats_wait_start(cfs_rq, prev);
2159 /* Put 'current' back into the tree. */
2160 __enqueue_entity(cfs_rq, prev);
2161 /* in !on_rq case, update occurred at dequeue */
2162 update_entity_load_avg(prev, 1);
2164 cfs_rq->curr = NULL;
2168 entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
2171 * Update run-time statistics of the 'current'.
2173 update_curr(cfs_rq);
2176 * Ensure that runnable average is periodically updated.
2178 update_entity_load_avg(curr, 1);
2179 update_cfs_rq_blocked_load(cfs_rq, 1);
2180 update_cfs_shares(cfs_rq);
2182 #ifdef CONFIG_SCHED_HRTICK
2184 * queued ticks are scheduled to match the slice, so don't bother
2185 * validating it and just reschedule.
2188 resched_task(rq_of(cfs_rq)->curr);
2192 * don't let the period tick interfere with the hrtick preemption
2194 if (!sched_feat(DOUBLE_TICK) &&
2195 hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
2199 if (cfs_rq->nr_running > 1)
2200 check_preempt_tick(cfs_rq, curr);
2204 /**************************************************
2205 * CFS bandwidth control machinery
2208 #ifdef CONFIG_CFS_BANDWIDTH
2210 #ifdef HAVE_JUMP_LABEL
2211 static struct static_key __cfs_bandwidth_used;
2213 static inline bool cfs_bandwidth_used(void)
2215 return static_key_false(&__cfs_bandwidth_used);
2218 void cfs_bandwidth_usage_inc(void)
2220 static_key_slow_inc(&__cfs_bandwidth_used);
2223 void cfs_bandwidth_usage_dec(void)
2225 static_key_slow_dec(&__cfs_bandwidth_used);
2227 #else /* HAVE_JUMP_LABEL */
2228 static bool cfs_bandwidth_used(void)
2233 void cfs_bandwidth_usage_inc(void) {}
2234 void cfs_bandwidth_usage_dec(void) {}
2235 #endif /* HAVE_JUMP_LABEL */
2238 * default period for cfs group bandwidth.
2239 * default: 0.1s, units: nanoseconds
2241 static inline u64 default_cfs_period(void)
2243 return 100000000ULL;
2246 static inline u64 sched_cfs_bandwidth_slice(void)
2248 return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
2252 * Replenish runtime according to assigned quota and update expiration time.
2253 * We use sched_clock_cpu directly instead of rq->clock to avoid adding
2254 * additional synchronization around rq->lock.
2256 * requires cfs_b->lock
2258 void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
2262 if (cfs_b->quota == RUNTIME_INF)
2265 now = sched_clock_cpu(smp_processor_id());
2266 cfs_b->runtime = cfs_b->quota;
2267 cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period);
2270 static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
2272 return &tg->cfs_bandwidth;
2275 /* rq->task_clock normalized against any time this cfs_rq has spent throttled */
2276 static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
2278 if (unlikely(cfs_rq->throttle_count))
2279 return cfs_rq->throttled_clock_task;
2281 return rq_of(cfs_rq)->clock_task - cfs_rq->throttled_clock_task_time;
2284 /* returns 0 on failure to allocate runtime */
2285 static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2287 struct task_group *tg = cfs_rq->tg;
2288 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
2289 u64 amount = 0, min_amount, expires;
2291 /* note: this is a positive sum as runtime_remaining <= 0 */
2292 min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining;
2294 raw_spin_lock(&cfs_b->lock);
2295 if (cfs_b->quota == RUNTIME_INF)
2296 amount = min_amount;
2299 * If the bandwidth pool has become inactive, then at least one
2300 * period must have elapsed since the last consumption.
2301 * Refresh the global state and ensure bandwidth timer becomes
2304 if (!cfs_b->timer_active) {
2305 __refill_cfs_bandwidth_runtime(cfs_b);
2306 __start_cfs_bandwidth(cfs_b);
2309 if (cfs_b->runtime > 0) {
2310 amount = min(cfs_b->runtime, min_amount);
2311 cfs_b->runtime -= amount;
2315 expires = cfs_b->runtime_expires;
2316 raw_spin_unlock(&cfs_b->lock);
2318 cfs_rq->runtime_remaining += amount;
2320 * we may have advanced our local expiration to account for allowed
2321 * spread between our sched_clock and the one on which runtime was
2324 if ((s64)(expires - cfs_rq->runtime_expires) > 0)
2325 cfs_rq->runtime_expires = expires;
2327 return cfs_rq->runtime_remaining > 0;
2331 * Note: This depends on the synchronization provided by sched_clock and the
2332 * fact that rq->clock snapshots this value.
2334 static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2336 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2337 struct rq *rq = rq_of(cfs_rq);
2339 /* if the deadline is ahead of our clock, nothing to do */
2340 if (likely((s64)(rq->clock - cfs_rq->runtime_expires) < 0))
2343 if (cfs_rq->runtime_remaining < 0)
2347 * If the local deadline has passed we have to consider the
2348 * possibility that our sched_clock is 'fast' and the global deadline
2349 * has not truly expired.
2351 * Fortunately we can check determine whether this the case by checking
2352 * whether the global deadline has advanced.
2355 if ((s64)(cfs_rq->runtime_expires - cfs_b->runtime_expires) >= 0) {
2356 /* extend local deadline, drift is bounded above by 2 ticks */
2357 cfs_rq->runtime_expires += TICK_NSEC;
2359 /* global deadline is ahead, expiration has passed */
2360 cfs_rq->runtime_remaining = 0;
2364 static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
2365 unsigned long delta_exec)
2367 /* dock delta_exec before expiring quota (as it could span periods) */
2368 cfs_rq->runtime_remaining -= delta_exec;
2369 expire_cfs_rq_runtime(cfs_rq);
2371 if (likely(cfs_rq->runtime_remaining > 0))
2375 * if we're unable to extend our runtime we resched so that the active
2376 * hierarchy can be throttled
2378 if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
2379 resched_task(rq_of(cfs_rq)->curr);
2382 static __always_inline
2383 void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec)
2385 if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
2388 __account_cfs_rq_runtime(cfs_rq, delta_exec);
2391 static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
2393 return cfs_bandwidth_used() && cfs_rq->throttled;
2396 /* check whether cfs_rq, or any parent, is throttled */
2397 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
2399 return cfs_bandwidth_used() && cfs_rq->throttle_count;
2403 * Ensure that neither of the group entities corresponding to src_cpu or
2404 * dest_cpu are members of a throttled hierarchy when performing group
2405 * load-balance operations.
2407 static inline int throttled_lb_pair(struct task_group *tg,
2408 int src_cpu, int dest_cpu)
2410 struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
2412 src_cfs_rq = tg->cfs_rq[src_cpu];
2413 dest_cfs_rq = tg->cfs_rq[dest_cpu];
2415 return throttled_hierarchy(src_cfs_rq) ||
2416 throttled_hierarchy(dest_cfs_rq);
2419 /* updated child weight may affect parent so we have to do this bottom up */
2420 static int tg_unthrottle_up(struct task_group *tg, void *data)
2422 struct rq *rq = data;
2423 struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
2425 cfs_rq->throttle_count--;
2427 if (!cfs_rq->throttle_count) {
2428 /* adjust cfs_rq_clock_task() */
2429 cfs_rq->throttled_clock_task_time += rq->clock_task -
2430 cfs_rq->throttled_clock_task;
2437 static int tg_throttle_down(struct task_group *tg, void *data)
2439 struct rq *rq = data;
2440 struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
2442 /* group is entering throttled state, stop time */
2443 if (!cfs_rq->throttle_count)
2444 cfs_rq->throttled_clock_task = rq->clock_task;
2445 cfs_rq->throttle_count++;
2450 static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
2452 struct rq *rq = rq_of(cfs_rq);
2453 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2454 struct sched_entity *se;
2455 long task_delta, dequeue = 1;
2457 se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
2459 /* freeze hierarchy runnable averages while throttled */
2461 walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
2464 task_delta = cfs_rq->h_nr_running;
2465 for_each_sched_entity(se) {
2466 struct cfs_rq *qcfs_rq = cfs_rq_of(se);
2467 /* throttled entity or throttle-on-deactivate */
2472 dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
2473 qcfs_rq->h_nr_running -= task_delta;
2475 if (qcfs_rq->load.weight)
2480 rq->nr_running -= task_delta;
2482 cfs_rq->throttled = 1;
2483 cfs_rq->throttled_clock = rq->clock;
2484 raw_spin_lock(&cfs_b->lock);
2485 list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
2486 if (!cfs_b->timer_active)
2487 __start_cfs_bandwidth(cfs_b);
2488 raw_spin_unlock(&cfs_b->lock);
2491 void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
2493 struct rq *rq = rq_of(cfs_rq);
2494 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2495 struct sched_entity *se;
2499 se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
2501 cfs_rq->throttled = 0;
2502 raw_spin_lock(&cfs_b->lock);
2503 cfs_b->throttled_time += rq->clock - cfs_rq->throttled_clock;
2504 list_del_rcu(&cfs_rq->throttled_list);
2505 raw_spin_unlock(&cfs_b->lock);
2507 update_rq_clock(rq);
2508 /* update hierarchical throttle state */
2509 walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
2511 if (!cfs_rq->load.weight)
2514 task_delta = cfs_rq->h_nr_running;
2515 for_each_sched_entity(se) {
2519 cfs_rq = cfs_rq_of(se);
2521 enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);
2522 cfs_rq->h_nr_running += task_delta;
2524 if (cfs_rq_throttled(cfs_rq))
2529 rq->nr_running += task_delta;
2531 /* determine whether we need to wake up potentially idle cpu */
2532 if (rq->curr == rq->idle && rq->cfs.nr_running)
2533 resched_task(rq->curr);
2536 static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
2537 u64 remaining, u64 expires)
2539 struct cfs_rq *cfs_rq;
2540 u64 runtime = remaining;
2543 list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
2545 struct rq *rq = rq_of(cfs_rq);
2547 raw_spin_lock(&rq->lock);
2548 if (!cfs_rq_throttled(cfs_rq))
2551 runtime = -cfs_rq->runtime_remaining + 1;
2552 if (runtime > remaining)
2553 runtime = remaining;
2554 remaining -= runtime;
2556 cfs_rq->runtime_remaining += runtime;
2557 cfs_rq->runtime_expires = expires;
2559 /* we check whether we're throttled above */
2560 if (cfs_rq->runtime_remaining > 0)
2561 unthrottle_cfs_rq(cfs_rq);
2564 raw_spin_unlock(&rq->lock);
2575 * Responsible for refilling a task_group's bandwidth and unthrottling its
2576 * cfs_rqs as appropriate. If there has been no activity within the last
2577 * period the timer is deactivated until scheduling resumes; cfs_b->idle is
2578 * used to track this state.
2580 static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
2582 u64 runtime, runtime_expires;
2583 int idle = 1, throttled;
2585 raw_spin_lock(&cfs_b->lock);
2586 /* no need to continue the timer with no bandwidth constraint */
2587 if (cfs_b->quota == RUNTIME_INF)
2590 throttled = !list_empty(&cfs_b->throttled_cfs_rq);
2591 /* idle depends on !throttled (for the case of a large deficit) */
2592 idle = cfs_b->idle && !throttled;
2593 cfs_b->nr_periods += overrun;
2595 /* if we're going inactive then everything else can be deferred */
2600 * if we have relooped after returning idle once, we need to update our
2601 * status as actually running, so that other cpus doing
2602 * __start_cfs_bandwidth will stop trying to cancel us.
2604 cfs_b->timer_active = 1;
2606 __refill_cfs_bandwidth_runtime(cfs_b);
2609 /* mark as potentially idle for the upcoming period */
2614 /* account preceding periods in which throttling occurred */
2615 cfs_b->nr_throttled += overrun;
2618 * There are throttled entities so we must first use the new bandwidth
2619 * to unthrottle them before making it generally available. This
2620 * ensures that all existing debts will be paid before a new cfs_rq is
2623 runtime = cfs_b->runtime;
2624 runtime_expires = cfs_b->runtime_expires;
2628 * This check is repeated as we are holding onto the new bandwidth
2629 * while we unthrottle. This can potentially race with an unthrottled
2630 * group trying to acquire new bandwidth from the global pool.
2632 while (throttled && runtime > 0) {
2633 raw_spin_unlock(&cfs_b->lock);
2634 /* we can't nest cfs_b->lock while distributing bandwidth */
2635 runtime = distribute_cfs_runtime(cfs_b, runtime,
2637 raw_spin_lock(&cfs_b->lock);
2639 throttled = !list_empty(&cfs_b->throttled_cfs_rq);
2642 /* return (any) remaining runtime */
2643 cfs_b->runtime = runtime;
2645 * While we are ensured activity in the period following an
2646 * unthrottle, this also covers the case in which the new bandwidth is
2647 * insufficient to cover the existing bandwidth deficit. (Forcing the
2648 * timer to remain active while there are any throttled entities.)
2653 cfs_b->timer_active = 0;
2654 raw_spin_unlock(&cfs_b->lock);
2659 /* a cfs_rq won't donate quota below this amount */
2660 static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
2661 /* minimum remaining period time to redistribute slack quota */
2662 static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
2663 /* how long we wait to gather additional slack before distributing */
2664 static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
2667 * Are we near the end of the current quota period?
2669 * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the
2670 * hrtimer base being cleared by __hrtimer_start_range_ns. In the case of
2671 * migrate_hrtimers, base is never cleared, so we are fine.
2673 static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
2675 struct hrtimer *refresh_timer = &cfs_b->period_timer;
2678 /* if the call-back is running a quota refresh is already occurring */
2679 if (hrtimer_callback_running(refresh_timer))
2682 /* is a quota refresh about to occur? */
2683 remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
2684 if (remaining < min_expire)
2690 static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
2692 u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
2694 /* if there's a quota refresh soon don't bother with slack */
2695 if (runtime_refresh_within(cfs_b, min_left))
2698 start_bandwidth_timer(&cfs_b->slack_timer,
2699 ns_to_ktime(cfs_bandwidth_slack_period));
2702 /* we know any runtime found here is valid as update_curr() precedes return */
2703 static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2705 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2706 s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
2708 if (slack_runtime <= 0)
2711 raw_spin_lock(&cfs_b->lock);
2712 if (cfs_b->quota != RUNTIME_INF &&
2713 cfs_rq->runtime_expires == cfs_b->runtime_expires) {
2714 cfs_b->runtime += slack_runtime;
2716 /* we are under rq->lock, defer unthrottling using a timer */
2717 if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
2718 !list_empty(&cfs_b->throttled_cfs_rq))
2719 start_cfs_slack_bandwidth(cfs_b);
2721 raw_spin_unlock(&cfs_b->lock);
2723 /* even if it's not valid for return we don't want to try again */
2724 cfs_rq->runtime_remaining -= slack_runtime;
2727 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2729 if (!cfs_bandwidth_used())
2732 if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
2735 __return_cfs_rq_runtime(cfs_rq);
2739 * This is done with a timer (instead of inline with bandwidth return) since
2740 * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
2742 static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
2744 u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
2747 /* confirm we're still not at a refresh boundary */
2748 raw_spin_lock(&cfs_b->lock);
2749 if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) {
2750 raw_spin_unlock(&cfs_b->lock);
2754 if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) {
2755 runtime = cfs_b->runtime;
2758 expires = cfs_b->runtime_expires;
2759 raw_spin_unlock(&cfs_b->lock);
2764 runtime = distribute_cfs_runtime(cfs_b, runtime, expires);
2766 raw_spin_lock(&cfs_b->lock);
2767 if (expires == cfs_b->runtime_expires)
2768 cfs_b->runtime = runtime;
2769 raw_spin_unlock(&cfs_b->lock);
2773 * When a group wakes up we want to make sure that its quota is not already
2774 * expired/exceeded, otherwise it may be allowed to steal additional ticks of
2775 * runtime as update_curr() throttling can not not trigger until it's on-rq.
2777 static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
2779 if (!cfs_bandwidth_used())
2782 /* an active group must be handled by the update_curr()->put() path */
2783 if (!cfs_rq->runtime_enabled || cfs_rq->curr)
2786 /* ensure the group is not already throttled */
2787 if (cfs_rq_throttled(cfs_rq))
2790 /* update runtime allocation */
2791 account_cfs_rq_runtime(cfs_rq, 0);
2792 if (cfs_rq->runtime_remaining <= 0)
2793 throttle_cfs_rq(cfs_rq);
2796 /* conditionally throttle active cfs_rq's from put_prev_entity() */
2797 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2799 if (!cfs_bandwidth_used())
2802 if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
2806 * it's possible for a throttled entity to be forced into a running
2807 * state (e.g. set_curr_task), in this case we're finished.
2809 if (cfs_rq_throttled(cfs_rq))
2812 throttle_cfs_rq(cfs_rq);
2815 static inline u64 default_cfs_period(void);
2816 static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun);
2817 static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b);
2819 static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
2821 struct cfs_bandwidth *cfs_b =
2822 container_of(timer, struct cfs_bandwidth, slack_timer);
2823 do_sched_cfs_slack_timer(cfs_b);
2825 return HRTIMER_NORESTART;
2828 static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
2830 struct cfs_bandwidth *cfs_b =
2831 container_of(timer, struct cfs_bandwidth, period_timer);
2837 now = hrtimer_cb_get_time(timer);
2838 overrun = hrtimer_forward(timer, now, cfs_b->period);
2843 idle = do_sched_cfs_period_timer(cfs_b, overrun);
2846 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
2849 void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2851 raw_spin_lock_init(&cfs_b->lock);
2853 cfs_b->quota = RUNTIME_INF;
2854 cfs_b->period = ns_to_ktime(default_cfs_period());
2856 INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
2857 hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
2858 cfs_b->period_timer.function = sched_cfs_period_timer;
2859 hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
2860 cfs_b->slack_timer.function = sched_cfs_slack_timer;
2863 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2865 cfs_rq->runtime_enabled = 0;
2866 INIT_LIST_HEAD(&cfs_rq->throttled_list);
2869 /* requires cfs_b->lock, may release to reprogram timer */
2870 void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2873 * The timer may be active because we're trying to set a new bandwidth
2874 * period or because we're racing with the tear-down path
2875 * (timer_active==0 becomes visible before the hrtimer call-back
2876 * terminates). In either case we ensure that it's re-programmed
2878 while (unlikely(hrtimer_active(&cfs_b->period_timer)) &&
2879 hrtimer_try_to_cancel(&cfs_b->period_timer) < 0) {
2880 /* bounce the lock to allow do_sched_cfs_period_timer to run */
2881 raw_spin_unlock(&cfs_b->lock);
2883 raw_spin_lock(&cfs_b->lock);
2884 /* if someone else restarted the timer then we're done */
2885 if (cfs_b->timer_active)
2889 cfs_b->timer_active = 1;
2890 start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period);
2893 static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2895 hrtimer_cancel(&cfs_b->period_timer);
2896 hrtimer_cancel(&cfs_b->slack_timer);
2899 static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
2901 struct cfs_rq *cfs_rq;
2903 for_each_leaf_cfs_rq(rq, cfs_rq) {
2904 struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2906 if (!cfs_rq->runtime_enabled)
2910 * clock_task is not advancing so we just need to make sure
2911 * there's some valid quota amount
2913 cfs_rq->runtime_remaining = cfs_b->quota;
2914 if (cfs_rq_throttled(cfs_rq))
2915 unthrottle_cfs_rq(cfs_rq);
2919 #else /* CONFIG_CFS_BANDWIDTH */
2920 static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
2922 return rq_of(cfs_rq)->clock_task;
2925 static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
2926 unsigned long delta_exec) {}
2927 static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2928 static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
2929 static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2931 static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
2936 static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
2941 static inline int throttled_lb_pair(struct task_group *tg,
2942 int src_cpu, int dest_cpu)
2947 void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
2949 #ifdef CONFIG_FAIR_GROUP_SCHED
2950 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2953 static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
2957 static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
2958 static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
2960 #endif /* CONFIG_CFS_BANDWIDTH */
2962 /**************************************************
2963 * CFS operations on tasks:
2966 #ifdef CONFIG_SCHED_HRTICK
2967 static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
2969 struct sched_entity *se = &p->se;
2970 struct cfs_rq *cfs_rq = cfs_rq_of(se);
2972 WARN_ON(task_rq(p) != rq);
2974 if (cfs_rq->nr_running > 1) {
2975 u64 slice = sched_slice(cfs_rq, se);
2976 u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
2977 s64 delta = slice - ran;
2986 * Don't schedule slices shorter than 10000ns, that just
2987 * doesn't make sense. Rely on vruntime for fairness.
2990 delta = max_t(s64, 10000LL, delta);
2992 hrtick_start(rq, delta);
2997 * called from enqueue/dequeue and updates the hrtick when the
2998 * current task is from our class and nr_running is low enough
3001 static void hrtick_update(struct rq *rq)
3003 struct task_struct *curr = rq->curr;
3005 if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class)
3008 if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
3009 hrtick_start_fair(rq, curr);
3011 #else /* !CONFIG_SCHED_HRTICK */
3013 hrtick_start_fair(struct rq *rq, struct task_struct *p)
3017 static inline void hrtick_update(struct rq *rq)
3023 * The enqueue_task method is called before nr_running is
3024 * increased. Here we update the fair scheduling stats and
3025 * then put the task into the rbtree:
3028 enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
3030 struct cfs_rq *cfs_rq;
3031 struct sched_entity *se = &p->se;
3033 for_each_sched_entity(se) {
3036 cfs_rq = cfs_rq_of(se);
3037 enqueue_entity(cfs_rq, se, flags);
3040 * end evaluation on encountering a throttled cfs_rq
3042 * note: in the case of encountering a throttled cfs_rq we will
3043 * post the final h_nr_running increment below.
3045 if (cfs_rq_throttled(cfs_rq))
3047 cfs_rq->h_nr_running++;
3049 flags = ENQUEUE_WAKEUP;
3052 for_each_sched_entity(se) {
3053 cfs_rq = cfs_rq_of(se);
3054 cfs_rq->h_nr_running++;
3056 if (cfs_rq_throttled(cfs_rq))
3059 update_cfs_shares(cfs_rq);
3060 update_entity_load_avg(se, 1);
3064 update_rq_runnable_avg(rq, rq->nr_running);
3070 static void set_next_buddy(struct sched_entity *se);
3073 * The dequeue_task method is called before nr_running is
3074 * decreased. We remove the task from the rbtree and
3075 * update the fair scheduling stats:
3077 static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
3079 struct cfs_rq *cfs_rq;
3080 struct sched_entity *se = &p->se;
3081 int task_sleep = flags & DEQUEUE_SLEEP;
3083 for_each_sched_entity(se) {
3084 cfs_rq = cfs_rq_of(se);
3085 dequeue_entity(cfs_rq, se, flags);
3088 * end evaluation on encountering a throttled cfs_rq
3090 * note: in the case of encountering a throttled cfs_rq we will
3091 * post the final h_nr_running decrement below.
3093 if (cfs_rq_throttled(cfs_rq))
3095 cfs_rq->h_nr_running--;
3097 /* Don't dequeue parent if it has other entities besides us */
3098 if (cfs_rq->load.weight) {
3100 * Bias pick_next to pick a task from this cfs_rq, as
3101 * p is sleeping when it is within its sched_slice.
3103 if (task_sleep && parent_entity(se))
3104 set_next_buddy(parent_entity(se));
3106 /* avoid re-evaluating load for this entity */
3107 se = parent_entity(se);
3110 flags |= DEQUEUE_SLEEP;
3113 for_each_sched_entity(se) {
3114 cfs_rq = cfs_rq_of(se);
3115 cfs_rq->h_nr_running--;
3117 if (cfs_rq_throttled(cfs_rq))
3120 update_cfs_shares(cfs_rq);
3121 update_entity_load_avg(se, 1);
3126 update_rq_runnable_avg(rq, 1);
3132 /* Used instead of source_load when we know the type == 0 */
3133 static unsigned long weighted_cpuload(const int cpu)
3135 return cpu_rq(cpu)->load.weight;
3139 * Return a low guess at the load of a migration-source cpu weighted
3140 * according to the scheduling class and "nice" value.
3142 * We want to under-estimate the load of migration sources, to
3143 * balance conservatively.
3145 static unsigned long source_load(int cpu, int type)
3147 struct rq *rq = cpu_rq(cpu);
3148 unsigned long total = weighted_cpuload(cpu);
3150 if (type == 0 || !sched_feat(LB_BIAS))
3153 return min(rq->cpu_load[type-1], total);
3157 * Return a high guess at the load of a migration-target cpu weighted
3158 * according to the scheduling class and "nice" value.
3160 static unsigned long target_load(int cpu, int type)
3162 struct rq *rq = cpu_rq(cpu);
3163 unsigned long total = weighted_cpuload(cpu);
3165 if (type == 0 || !sched_feat(LB_BIAS))
3168 return max(rq->cpu_load[type-1], total);
3171 static unsigned long power_of(int cpu)
3173 return cpu_rq(cpu)->cpu_power;
3176 static unsigned long cpu_avg_load_per_task(int cpu)
3178 struct rq *rq = cpu_rq(cpu);
3179 unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
3182 return rq->load.weight / nr_running;
3188 static void task_waking_fair(struct task_struct *p)
3190 struct sched_entity *se = &p->se;
3191 struct cfs_rq *cfs_rq = cfs_rq_of(se);
3194 #ifndef CONFIG_64BIT
3195 u64 min_vruntime_copy;
3198 min_vruntime_copy = cfs_rq->min_vruntime_copy;
3200 min_vruntime = cfs_rq->min_vruntime;
3201 } while (min_vruntime != min_vruntime_copy);
3203 min_vruntime = cfs_rq->min_vruntime;
3206 se->vruntime -= min_vruntime;
3209 #ifdef CONFIG_FAIR_GROUP_SCHED
3211 * effective_load() calculates the load change as seen from the root_task_group
3213 * Adding load to a group doesn't make a group heavier, but can cause movement
3214 * of group shares between cpus. Assuming the shares were perfectly aligned one
3215 * can calculate the shift in shares.
3217 * Calculate the effective load difference if @wl is added (subtracted) to @tg
3218 * on this @cpu and results in a total addition (subtraction) of @wg to the
3219 * total group weight.
3221 * Given a runqueue weight distribution (rw_i) we can compute a shares
3222 * distribution (s_i) using:
3224 * s_i = rw_i / \Sum rw_j (1)
3226 * Suppose we have 4 CPUs and our @tg is a direct child of the root group and
3227 * has 7 equal weight tasks, distributed as below (rw_i), with the resulting
3228 * shares distribution (s_i):
3230 * rw_i = { 2, 4, 1, 0 }
3231 * s_i = { 2/7, 4/7, 1/7, 0 }
3233 * As per wake_affine() we're interested in the load of two CPUs (the CPU the
3234 * task used to run on and the CPU the waker is running on), we need to
3235 * compute the effect of waking a task on either CPU and, in case of a sync
3236 * wakeup, compute the effect of the current task going to sleep.
3238 * So for a change of @wl to the local @cpu with an overall group weight change
3239 * of @wl we can compute the new shares distribution (s'_i) using:
3241 * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2)
3243 * Suppose we're interested in CPUs 0 and 1, and want to compute the load
3244 * differences in waking a task to CPU 0. The additional task changes the
3245 * weight and shares distributions like:
3247 * rw'_i = { 3, 4, 1, 0 }
3248 * s'_i = { 3/8, 4/8, 1/8, 0 }
3250 * We can then compute the difference in effective weight by using:
3252 * dw_i = S * (s'_i - s_i) (3)
3254 * Where 'S' is the group weight as seen by its parent.
3256 * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7)
3257 * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 -
3258 * 4/7) times the weight of the group.
3260 static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
3262 struct sched_entity *se = tg->se[cpu];
3264 if (!tg->parent) /* the trivial, non-cgroup case */
3267 for_each_sched_entity(se) {
3273 * W = @wg + \Sum rw_j
3275 W = wg + calc_tg_weight(tg, se->my_q);
3280 w = se->my_q->load.weight + wl;
3283 * wl = S * s'_i; see (2)
3286 wl = (w * tg->shares) / W;
3291 * Per the above, wl is the new se->load.weight value; since
3292 * those are clipped to [MIN_SHARES, ...) do so now. See
3293 * calc_cfs_shares().
3295 if (wl < MIN_SHARES)
3299 * wl = dw_i = S * (s'_i - s_i); see (3)
3301 wl -= se->load.weight;
3304 * Recursively apply this logic to all parent groups to compute
3305 * the final effective load change on the root group. Since
3306 * only the @tg group gets extra weight, all parent groups can
3307 * only redistribute existing shares. @wl is the shift in shares
3308 * resulting from this level per the above.
3317 static inline unsigned long effective_load(struct task_group *tg, int cpu,
3318 unsigned long wl, unsigned long wg)
3325 static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
3327 s64 this_load, load;
3328 int idx, this_cpu, prev_cpu;
3329 unsigned long tl_per_task;
3330 struct task_group *tg;
3331 unsigned long weight;
3335 this_cpu = smp_processor_id();
3336 prev_cpu = task_cpu(p);
3337 load = source_load(prev_cpu, idx);
3338 this_load = target_load(this_cpu, idx);
3341 * If sync wakeup then subtract the (maximum possible)
3342 * effect of the currently running task from the load
3343 * of the current CPU:
3346 tg = task_group(current);
3347 weight = current->se.load.weight;
3349 this_load += effective_load(tg, this_cpu, -weight, -weight);
3350 load += effective_load(tg, prev_cpu, 0, -weight);
3354 weight = p->se.load.weight;
3357 * In low-load situations, where prev_cpu is idle and this_cpu is idle
3358 * due to the sync cause above having dropped this_load to 0, we'll
3359 * always have an imbalance, but there's really nothing you can do
3360 * about that, so that's good too.
3362 * Otherwise check if either cpus are near enough in load to allow this
3363 * task to be woken on this_cpu.
3365 if (this_load > 0) {
3366 s64 this_eff_load, prev_eff_load;
3368 this_eff_load = 100;
3369 this_eff_load *= power_of(prev_cpu);
3370 this_eff_load *= this_load +
3371 effective_load(tg, this_cpu, weight, weight);
3373 prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2;
3374 prev_eff_load *= power_of(this_cpu);
3375 prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight);
3377 balanced = this_eff_load <= prev_eff_load;
3382 * If the currently running task will sleep within
3383 * a reasonable amount of time then attract this newly
3386 if (sync && balanced)
3389 schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
3390 tl_per_task = cpu_avg_load_per_task(this_cpu);
3393 (this_load <= load &&
3394 this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
3396 * This domain has SD_WAKE_AFFINE and
3397 * p is cache cold in this domain, and
3398 * there is no bad imbalance.
3400 schedstat_inc(sd, ttwu_move_affine);
3401 schedstat_inc(p, se.statistics.nr_wakeups_affine);
3409 * find_idlest_group finds and returns the least busy CPU group within the
3412 static struct sched_group *
3413 find_idlest_group(struct sched_domain *sd, struct task_struct *p,
3414 int this_cpu, int load_idx)
3416 struct sched_group *idlest = NULL, *group = sd->groups;
3417 unsigned long min_load = ULONG_MAX, this_load = 0;
3418 int imbalance = 100 + (sd->imbalance_pct-100)/2;
3421 unsigned long load, avg_load;
3425 /* Skip over this group if it has no CPUs allowed */
3426 if (!cpumask_intersects(sched_group_cpus(group),
3427 tsk_cpus_allowed(p)))
3430 local_group = cpumask_test_cpu(this_cpu,
3431 sched_group_cpus(group));
3433 /* Tally up the load of all CPUs in the group */
3436 for_each_cpu(i, sched_group_cpus(group)) {
3437 /* Bias balancing toward cpus of our domain */
3439 load = source_load(i, load_idx);
3441 load = target_load(i, load_idx);
3446 /* Adjust by relative CPU power of the group */
3447 avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power;
3450 this_load = avg_load;
3451 } else if (avg_load < min_load) {
3452 min_load = avg_load;
3455 } while (group = group->next, group != sd->groups);
3457 if (!idlest || 100*this_load < imbalance*min_load)
3463 * find_idlest_cpu - find the idlest cpu among the cpus in group.
3466 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
3468 unsigned long load, min_load = ULONG_MAX;
3472 /* Traverse only the allowed CPUs */
3473 for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) {
3474 load = weighted_cpuload(i);
3476 if (load < min_load || (load == min_load && i == this_cpu)) {
3486 * Try and locate an idle CPU in the sched_domain.
3488 static int select_idle_sibling(struct task_struct *p, int target)
3490 struct sched_domain *sd;
3491 struct sched_group *sg;
3492 int i = task_cpu(p);
3494 if (idle_cpu(target))
3498 * If the prevous cpu is cache affine and idle, don't be stupid.
3500 if (i != target && cpus_share_cache(i, target) && idle_cpu(i))
3504 * Otherwise, iterate the domains and find an elegible idle cpu.
3506 sd = rcu_dereference(per_cpu(sd_llc, target));
3507 for_each_lower_domain(sd) {
3510 if (!cpumask_intersects(sched_group_cpus(sg),
3511 tsk_cpus_allowed(p)))
3514 for_each_cpu(i, sched_group_cpus(sg)) {
3515 if (i == target || !idle_cpu(i))
3519 target = cpumask_first_and(sched_group_cpus(sg),
3520 tsk_cpus_allowed(p));
3524 } while (sg != sd->groups);
3530 #ifdef CONFIG_SCHED_HMP
3532 * Heterogenous multiprocessor (HMP) optimizations
3534 * The cpu types are distinguished using a list of hmp_domains
3535 * which each represent one cpu type using a cpumask.
3536 * The list is assumed ordered by compute capacity with the
3537 * fastest domain first.
3539 DEFINE_PER_CPU(struct hmp_domain *, hmp_cpu_domain);
3540 static const int hmp_max_tasks = 5;
3542 extern void __init arch_get_hmp_domains(struct list_head *hmp_domains_list);
3544 /* Setup hmp_domains */
3545 static int __init hmp_cpu_mask_setup(void)
3548 struct hmp_domain *domain;
3549 struct list_head *pos;
3552 pr_debug("Initializing HMP scheduler:\n");
3554 /* Initialize hmp_domains using platform code */
3555 arch_get_hmp_domains(&hmp_domains);
3556 if (list_empty(&hmp_domains)) {
3557 pr_debug("HMP domain list is empty!\n");
3561 /* Print hmp_domains */
3563 list_for_each(pos, &hmp_domains) {
3564 domain = list_entry(pos, struct hmp_domain, hmp_domains);
3565 cpulist_scnprintf(buf, 64, &domain->possible_cpus);
3566 pr_debug(" HMP domain %d: %s\n", dc, buf);
3568 for_each_cpu_mask(cpu, domain->possible_cpus) {
3569 per_cpu(hmp_cpu_domain, cpu) = domain;
3577 static struct hmp_domain *hmp_get_hmp_domain_for_cpu(int cpu)
3579 struct hmp_domain *domain;
3580 struct list_head *pos;
3582 list_for_each(pos, &hmp_domains) {
3583 domain = list_entry(pos, struct hmp_domain, hmp_domains);
3584 if(cpumask_test_cpu(cpu, &domain->possible_cpus))
3590 static void hmp_online_cpu(int cpu)
3592 struct hmp_domain *domain = hmp_get_hmp_domain_for_cpu(cpu);
3595 cpumask_set_cpu(cpu, &domain->cpus);
3598 static void hmp_offline_cpu(int cpu)
3600 struct hmp_domain *domain = hmp_get_hmp_domain_for_cpu(cpu);
3603 cpumask_clear_cpu(cpu, &domain->cpus);
3606 * Needed to determine heaviest tasks etc.
3608 static inline unsigned int hmp_cpu_is_fastest(int cpu);
3609 static inline unsigned int hmp_cpu_is_slowest(int cpu);
3610 static inline struct hmp_domain *hmp_slower_domain(int cpu);
3611 static inline struct hmp_domain *hmp_faster_domain(int cpu);
3613 /* must hold runqueue lock for queue se is currently on */
3614 static struct sched_entity *hmp_get_heaviest_task(
3615 struct sched_entity *se, int migrate_up)
3617 int num_tasks = hmp_max_tasks;
3618 struct sched_entity *max_se = se;
3619 unsigned long int max_ratio = se->avg.load_avg_ratio;
3620 const struct cpumask *hmp_target_mask = NULL;
3623 struct hmp_domain *hmp;
3624 if (hmp_cpu_is_fastest(cpu_of(se->cfs_rq->rq)))
3627 hmp = hmp_faster_domain(cpu_of(se->cfs_rq->rq));
3628 hmp_target_mask = &hmp->cpus;
3630 /* The currently running task is not on the runqueue */
3631 se = __pick_first_entity(cfs_rq_of(se));
3633 while (num_tasks && se) {
3634 if (entity_is_task(se) &&
3635 (se->avg.load_avg_ratio > max_ratio &&
3637 cpumask_intersects(hmp_target_mask,
3638 tsk_cpus_allowed(task_of(se))))) {
3640 max_ratio = se->avg.load_avg_ratio;
3642 se = __pick_next_entity(se);
3648 static struct sched_entity *hmp_get_lightest_task(
3649 struct sched_entity *se, int migrate_down)
3651 int num_tasks = hmp_max_tasks;
3652 struct sched_entity *min_se = se;
3653 unsigned long int min_ratio = se->avg.load_avg_ratio;
3654 const struct cpumask *hmp_target_mask = NULL;
3657 struct hmp_domain *hmp;
3658 if (hmp_cpu_is_slowest(cpu_of(se->cfs_rq->rq)))
3660 hmp = hmp_slower_domain(cpu_of(se->cfs_rq->rq));
3661 hmp_target_mask = &hmp->cpus;
3663 /* The currently running task is not on the runqueue */
3664 se = __pick_first_entity(cfs_rq_of(se));
3666 while (num_tasks && se) {
3667 if (entity_is_task(se) &&
3668 (se->avg.load_avg_ratio < min_ratio &&
3670 cpumask_intersects(hmp_target_mask,
3671 tsk_cpus_allowed(task_of(se))))) {
3673 min_ratio = se->avg.load_avg_ratio;
3675 se = __pick_next_entity(se);
3682 * Migration thresholds should be in the range [0..1023]
3683 * hmp_up_threshold: min. load required for migrating tasks to a faster cpu
3684 * hmp_down_threshold: max. load allowed for tasks migrating to a slower cpu
3686 * hmp_up_prio: Only up migrate task with high priority (<hmp_up_prio)
3687 * hmp_next_up_threshold: Delay before next up migration (1024 ~= 1 ms)
3688 * hmp_next_down_threshold: Delay before next down migration (1024 ~= 1 ms)
3690 * Small Task Packing:
3691 * We can choose to fill the littlest CPUs in an HMP system rather than
3692 * the typical spreading mechanic. This behavior is controllable using
3694 * hmp_packing_enabled: runtime control over pack/spread
3695 * hmp_full_threshold: Consider a CPU with this much unweighted load full
3697 unsigned int hmp_up_threshold = 700;
3698 unsigned int hmp_down_threshold = 512;
3699 #ifdef CONFIG_SCHED_HMP_PRIO_FILTER
3700 unsigned int hmp_up_prio = NICE_TO_PRIO(CONFIG_SCHED_HMP_PRIO_FILTER_VAL);
3702 unsigned int hmp_next_up_threshold = 4096;
3703 unsigned int hmp_next_down_threshold = 4096;
3705 #ifdef CONFIG_SCHED_HMP_LITTLE_PACKING
3706 #ifndef CONFIG_ARCH_VEXPRESS_TC2
3707 unsigned int hmp_packing_enabled = 1;
3708 unsigned int hmp_full_threshold = (NICE_0_LOAD * 9) / 8;
3710 /* TC2 has a sharp consumption curve @ around 800Mhz, so
3711 we aim to spread the load around that frequency. */
3712 unsigned int hmp_packing_enabled;
3713 unsigned int hmp_full_threshold = 650; /* 80% of the 800Mhz freq * NICE_0_LOAD */
3717 static unsigned int hmp_up_migration(int cpu, int *target_cpu, struct sched_entity *se);
3718 static unsigned int hmp_down_migration(int cpu, struct sched_entity *se);
3719 static inline unsigned int hmp_domain_min_load(struct hmp_domain *hmpd,
3720 int *min_cpu, struct cpumask *affinity);
3722 static inline struct hmp_domain *hmp_smallest_domain(void)
3724 return list_entry(hmp_domains.prev, struct hmp_domain, hmp_domains);
3727 /* Check if cpu is in fastest hmp_domain */
3728 static inline unsigned int hmp_cpu_is_fastest(int cpu)
3730 struct list_head *pos;
3732 pos = &hmp_cpu_domain(cpu)->hmp_domains;
3733 return pos == hmp_domains.next;
3736 /* Check if cpu is in slowest hmp_domain */
3737 static inline unsigned int hmp_cpu_is_slowest(int cpu)
3739 struct list_head *pos;
3741 pos = &hmp_cpu_domain(cpu)->hmp_domains;
3742 return list_is_last(pos, &hmp_domains);
3745 /* Next (slower) hmp_domain relative to cpu */
3746 static inline struct hmp_domain *hmp_slower_domain(int cpu)
3748 struct list_head *pos;
3750 pos = &hmp_cpu_domain(cpu)->hmp_domains;
3751 return list_entry(pos->next, struct hmp_domain, hmp_domains);
3754 /* Previous (faster) hmp_domain relative to cpu */
3755 static inline struct hmp_domain *hmp_faster_domain(int cpu)
3757 struct list_head *pos;
3759 pos = &hmp_cpu_domain(cpu)->hmp_domains;
3760 return list_entry(pos->prev, struct hmp_domain, hmp_domains);
3764 * Selects a cpu in previous (faster) hmp_domain
3766 static inline unsigned int hmp_select_faster_cpu(struct task_struct *tsk,
3769 int lowest_cpu=NR_CPUS;
3770 __always_unused int lowest_ratio;
3771 struct hmp_domain *hmp;
3773 if (hmp_cpu_is_fastest(cpu))
3774 hmp = hmp_cpu_domain(cpu);
3776 hmp = hmp_faster_domain(cpu);
3778 lowest_ratio = hmp_domain_min_load(hmp, &lowest_cpu,
3779 tsk_cpus_allowed(tsk));
3785 * Selects a cpu in next (slower) hmp_domain
3786 * Note that cpumask_any_and() returns the first cpu in the cpumask
3788 static inline unsigned int hmp_select_slower_cpu(struct task_struct *tsk,
3791 int lowest_cpu=NR_CPUS;
3792 struct hmp_domain *hmp;
3793 __always_unused int lowest_ratio;
3795 if (hmp_cpu_is_slowest(cpu))
3796 hmp = hmp_cpu_domain(cpu);
3798 hmp = hmp_slower_domain(cpu);
3800 lowest_ratio = hmp_domain_min_load(hmp, &lowest_cpu,
3801 tsk_cpus_allowed(tsk));
3805 #ifdef CONFIG_SCHED_HMP_LITTLE_PACKING
3807 * Select the 'best' candidate little CPU to wake up on.
3808 * Implements a packing strategy which examines CPU in
3809 * logical CPU order, and selects the first which will
3810 * have at least 10% capacity available, according to
3811 * both tracked load of the runqueue and the task.
3813 static inline unsigned int hmp_best_little_cpu(struct task_struct *tsk,
3816 unsigned long estimated_load;
3817 struct hmp_domain *hmp;
3818 struct sched_avg *avg;
3819 struct cpumask allowed_hmp_cpus;
3821 if(!hmp_packing_enabled ||
3822 tsk->se.avg.load_avg_ratio > ((NICE_0_LOAD * 90)/100))
3823 return hmp_select_slower_cpu(tsk, cpu);
3825 if (hmp_cpu_is_slowest(cpu))
3826 hmp = hmp_cpu_domain(cpu);
3828 hmp = hmp_slower_domain(cpu);
3830 /* respect affinity */
3831 cpumask_and(&allowed_hmp_cpus, &hmp->cpus,
3832 tsk_cpus_allowed(tsk));
3834 for_each_cpu_mask(tmp_cpu, allowed_hmp_cpus) {
3835 avg = &cpu_rq(tmp_cpu)->avg;
3836 /* estimate new rq load if we add this task */
3837 estimated_load = avg->load_avg_ratio +
3838 tsk->se.avg.load_avg_ratio;
3839 if (estimated_load <= hmp_full_threshold) {
3844 /* if no match was found, the task uses the initial value */
3848 static inline void hmp_next_up_delay(struct sched_entity *se, int cpu)
3850 /* hack - always use clock from first online CPU */
3851 u64 now = cpu_rq(cpumask_first(cpu_online_mask))->clock_task;
3852 se->avg.hmp_last_up_migration = now;
3853 se->avg.hmp_last_down_migration = 0;
3854 cpu_rq(cpu)->avg.hmp_last_up_migration = now;
3855 cpu_rq(cpu)->avg.hmp_last_down_migration = 0;
3858 static inline void hmp_next_down_delay(struct sched_entity *se, int cpu)
3860 /* hack - always use clock from first online CPU */
3861 u64 now = cpu_rq(cpumask_first(cpu_online_mask))->clock_task;
3862 se->avg.hmp_last_down_migration = now;
3863 se->avg.hmp_last_up_migration = 0;
3864 cpu_rq(cpu)->avg.hmp_last_down_migration = now;
3865 cpu_rq(cpu)->avg.hmp_last_up_migration = 0;
3869 * Heterogenous multiprocessor (HMP) optimizations
3871 * These functions allow to change the growing speed of the load_avg_ratio
3872 * by default it goes from 0 to 0.5 in LOAD_AVG_PERIOD = 32ms
3873 * This can now be changed with /sys/kernel/hmp/load_avg_period_ms.
3875 * These functions also allow to change the up and down threshold of HMP
3876 * using /sys/kernel/hmp/{up,down}_threshold.
3877 * Both must be between 0 and 1023. The threshold that is compared
3878 * to the load_avg_ratio is up_threshold/1024 and down_threshold/1024.
3880 * For instance, if load_avg_period = 64 and up_threshold = 512, an idle
3881 * task with a load of 0 will reach the threshold after 64ms of busy loop.
3883 * Changing load_avg_periods_ms has the same effect than changing the
3884 * default scaling factor Y=1002/1024 in the load_avg_ratio computation to
3885 * (1002/1024.0)^(LOAD_AVG_PERIOD/load_avg_period_ms), but the last one
3886 * could trigger overflows.
3887 * For instance, with Y = 1023/1024 in __update_task_entity_contrib()
3888 * "contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);"
3889 * could be overflowed for a weight > 2^12 even is the load_avg_contrib
3890 * should still be a 32bits result. This would not happen by multiplicating
3891 * delta time by 1/22 and setting load_avg_period_ms = 706.
3895 * By scaling the delta time it end-up increasing or decrease the
3896 * growing speed of the per entity load_avg_ratio
3897 * The scale factor hmp_data.multiplier is a fixed point
3898 * number: (32-HMP_VARIABLE_SCALE_SHIFT).HMP_VARIABLE_SCALE_SHIFT
3900 static inline u64 hmp_variable_scale_convert(u64 delta)
3902 #ifdef CONFIG_HMP_VARIABLE_SCALE
3903 u64 high = delta >> 32ULL;
3904 u64 low = delta & 0xffffffffULL;
3905 low *= hmp_data.multiplier;
3906 high *= hmp_data.multiplier;
3907 return (low >> HMP_VARIABLE_SCALE_SHIFT)
3908 + (high << (32ULL - HMP_VARIABLE_SCALE_SHIFT));
3914 static ssize_t hmp_show(struct kobject *kobj,
3915 struct attribute *attr, char *buf)
3917 struct hmp_global_attr *hmp_attr =
3918 container_of(attr, struct hmp_global_attr, attr);
3921 if (hmp_attr->to_sysfs_text != NULL)
3922 return hmp_attr->to_sysfs_text(buf, PAGE_SIZE);
3924 temp = *(hmp_attr->value);
3925 if (hmp_attr->to_sysfs != NULL)
3926 temp = hmp_attr->to_sysfs(temp);
3928 return (ssize_t)sprintf(buf, "%d\n", temp);
3931 static ssize_t hmp_store(struct kobject *a, struct attribute *attr,
3932 const char *buf, size_t count)
3935 ssize_t ret = count;
3936 struct hmp_global_attr *hmp_attr =
3937 container_of(attr, struct hmp_global_attr, attr);
3938 char *str = vmalloc(count + 1);
3941 memcpy(str, buf, count);
3943 if (sscanf(str, "%d", &temp) < 1)
3946 if (hmp_attr->from_sysfs != NULL)
3947 temp = hmp_attr->from_sysfs(temp);
3951 *(hmp_attr->value) = temp;
3957 static ssize_t hmp_print_domains(char *outbuf, int outbufsize)
3960 const char nospace[] = "%s", space[] = " %s";
3961 const char *fmt = nospace;
3962 struct hmp_domain *domain;
3963 struct list_head *pos;
3965 list_for_each(pos, &hmp_domains) {
3966 domain = list_entry(pos, struct hmp_domain, hmp_domains);
3967 if (cpumask_scnprintf(buf, 64, &domain->possible_cpus)) {
3968 outpos += sprintf(outbuf+outpos, fmt, buf);
3972 strcat(outbuf, "\n");
3976 #ifdef CONFIG_HMP_VARIABLE_SCALE
3977 static int hmp_period_tofrom_sysfs(int value)
3979 return (LOAD_AVG_PERIOD << HMP_VARIABLE_SCALE_SHIFT) / value;
3982 /* max value for threshold is 1024 */
3983 static int hmp_theshold_from_sysfs(int value)
3989 #if defined(CONFIG_SCHED_HMP_LITTLE_PACKING) || \
3990 defined(CONFIG_HMP_FREQUENCY_INVARIANT_SCALE)
3991 /* toggle control is only 0,1 off/on */
3992 static int hmp_toggle_from_sysfs(int value)
3994 if (value < 0 || value > 1)
3999 #ifdef CONFIG_SCHED_HMP_LITTLE_PACKING
4000 /* packing value must be non-negative */
4001 static int hmp_packing_from_sysfs(int value)
4008 static void hmp_attr_add(
4011 int (*to_sysfs)(int),
4012 int (*from_sysfs)(int),
4013 ssize_t (*to_sysfs_text)(char *, int),
4017 while (hmp_data.attributes[i] != NULL) {
4019 if (i >= HMP_DATA_SYSFS_MAX)
4023 hmp_data.attr[i].attr.mode = mode;
4025 hmp_data.attr[i].attr.mode = 0644;
4026 hmp_data.attr[i].show = hmp_show;
4027 hmp_data.attr[i].store = hmp_store;
4028 hmp_data.attr[i].attr.name = name;
4029 hmp_data.attr[i].value = value;
4030 hmp_data.attr[i].to_sysfs = to_sysfs;
4031 hmp_data.attr[i].from_sysfs = from_sysfs;
4032 hmp_data.attr[i].to_sysfs_text = to_sysfs_text;
4033 hmp_data.attributes[i] = &hmp_data.attr[i].attr;
4034 hmp_data.attributes[i + 1] = NULL;
4037 static int hmp_attr_init(void)
4040 memset(&hmp_data, sizeof(hmp_data), 0);
4041 hmp_attr_add("hmp_domains",
4047 hmp_attr_add("up_threshold",
4050 hmp_theshold_from_sysfs,
4053 hmp_attr_add("down_threshold",
4054 &hmp_down_threshold,
4056 hmp_theshold_from_sysfs,
4059 #ifdef CONFIG_HMP_VARIABLE_SCALE
4060 /* by default load_avg_period_ms == LOAD_AVG_PERIOD
4063 hmp_data.multiplier = hmp_period_tofrom_sysfs(LOAD_AVG_PERIOD);
4064 hmp_attr_add("load_avg_period_ms",
4065 &hmp_data.multiplier,
4066 hmp_period_tofrom_sysfs,
4067 hmp_period_tofrom_sysfs,
4071 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
4072 /* default frequency-invariant scaling ON */
4073 hmp_data.freqinvar_load_scale_enabled = 1;
4074 hmp_attr_add("frequency_invariant_load_scale",
4075 &hmp_data.freqinvar_load_scale_enabled,
4077 hmp_toggle_from_sysfs,
4081 #ifdef CONFIG_SCHED_HMP_LITTLE_PACKING
4082 hmp_attr_add("packing_enable",
4083 &hmp_packing_enabled,
4085 hmp_toggle_from_sysfs,
4088 hmp_attr_add("packing_limit",
4089 &hmp_full_threshold,
4091 hmp_packing_from_sysfs,
4095 hmp_data.attr_group.name = "hmp";
4096 hmp_data.attr_group.attrs = hmp_data.attributes;
4097 ret = sysfs_create_group(kernel_kobj,
4098 &hmp_data.attr_group);
4101 late_initcall(hmp_attr_init);
4103 * return the load of the lowest-loaded CPU in a given HMP domain
4104 * min_cpu optionally points to an int to receive the CPU.
4105 * affinity optionally points to a cpumask containing the
4106 * CPUs to be considered. note:
4107 * + min_cpu = NR_CPUS only if no CPUs are in the set of
4108 * affinity && hmp_domain cpus
4109 * + min_cpu will always otherwise equal one of the CPUs in
4111 * + when more than one CPU has the same load, the one which
4112 * is least-recently-disturbed by an HMP migration will be
4114 * + if all CPUs are equally loaded or idle and the times are
4115 * all the same, the first in the set will be used
4116 * + if affinity is not set, cpu_online_mask is used
4118 static inline unsigned int hmp_domain_min_load(struct hmp_domain *hmpd,
4119 int *min_cpu, struct cpumask *affinity)
4122 int min_cpu_runnable_temp = NR_CPUS;
4123 u64 min_target_last_migration = ULLONG_MAX;
4124 u64 curr_last_migration;
4125 unsigned long min_runnable_load = INT_MAX;
4126 unsigned long contrib;
4127 struct sched_avg *avg;
4128 struct cpumask temp_cpumask;
4130 * only look at CPUs allowed if specified,
4131 * otherwise look at all online CPUs in the
4134 cpumask_and(&temp_cpumask, &hmpd->cpus, affinity ? affinity : cpu_online_mask);
4136 for_each_cpu_mask(cpu, temp_cpumask) {
4137 avg = &cpu_rq(cpu)->avg;
4138 /* used for both up and down migration */
4139 curr_last_migration = avg->hmp_last_up_migration ?
4140 avg->hmp_last_up_migration : avg->hmp_last_down_migration;
4142 contrib = avg->load_avg_ratio;
4144 * Consider a runqueue completely busy if there is any load
4145 * on it. Definitely not the best for overall fairness, but
4146 * does well in typical Android use cases.
4151 if ((contrib < min_runnable_load) ||
4152 (contrib == min_runnable_load &&
4153 curr_last_migration < min_target_last_migration)) {
4155 * if the load is the same target the CPU with
4156 * the longest time since a migration.
4157 * This is to spread migration load between
4158 * members of a domain more evenly when the
4159 * domain is fully loaded
4161 min_runnable_load = contrib;
4162 min_cpu_runnable_temp = cpu;
4163 min_target_last_migration = curr_last_migration;
4168 *min_cpu = min_cpu_runnable_temp;
4170 return min_runnable_load;
4174 * Calculate the task starvation
4175 * This is the ratio of actually running time vs. runnable time.
4176 * If the two are equal the task is getting the cpu time it needs or
4177 * it is alone on the cpu and the cpu is fully utilized.
4179 static inline unsigned int hmp_task_starvation(struct sched_entity *se)
4183 starvation = se->avg.usage_avg_sum * scale_load_down(NICE_0_LOAD);
4184 starvation /= (se->avg.runnable_avg_sum + 1);
4186 return scale_load(starvation);
4189 static inline unsigned int hmp_offload_down(int cpu, struct sched_entity *se)
4192 int dest_cpu = NR_CPUS;
4194 if (hmp_cpu_is_slowest(cpu))
4197 /* Is there an idle CPU in the current domain */
4198 min_usage = hmp_domain_min_load(hmp_cpu_domain(cpu), NULL, NULL);
4199 if (min_usage == 0) {
4200 trace_sched_hmp_offload_abort(cpu, min_usage, "load");
4204 /* Is the task alone on the cpu? */
4205 if (cpu_rq(cpu)->cfs.h_nr_running < 2) {
4206 trace_sched_hmp_offload_abort(cpu,
4207 cpu_rq(cpu)->cfs.h_nr_running, "nr_running");
4211 /* Is the task actually starving? */
4212 /* >=25% ratio running/runnable = starving */
4213 if (hmp_task_starvation(se) > 768) {
4214 trace_sched_hmp_offload_abort(cpu, hmp_task_starvation(se),
4219 /* Does the slower domain have any idle CPUs? */
4220 min_usage = hmp_domain_min_load(hmp_slower_domain(cpu), &dest_cpu,
4221 tsk_cpus_allowed(task_of(se)));
4223 if (min_usage == 0) {
4224 trace_sched_hmp_offload_succeed(cpu, dest_cpu);
4227 trace_sched_hmp_offload_abort(cpu,min_usage,"slowdomain");
4230 #endif /* CONFIG_SCHED_HMP */
4233 * sched_balance_self: balance the current task (running on cpu) in domains
4234 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
4237 * Balance, ie. select the least loaded group.
4239 * Returns the target CPU number, or the same CPU if no balancing is needed.
4241 * preempt must be disabled.
4244 select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
4246 struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
4247 int cpu = smp_processor_id();
4248 int prev_cpu = task_cpu(p);
4250 int want_affine = 0;
4251 int sync = wake_flags & WF_SYNC;
4253 if (p->nr_cpus_allowed == 1)
4256 #ifdef CONFIG_SCHED_HMP
4257 /* always put non-kernel forking tasks on a big domain */
4258 if (p->mm && (sd_flag & SD_BALANCE_FORK)) {
4259 new_cpu = hmp_select_faster_cpu(p, prev_cpu);
4260 if (new_cpu != NR_CPUS) {
4261 hmp_next_up_delay(&p->se, new_cpu);
4264 /* failed to perform HMP fork balance, use normal balance */
4269 if (sd_flag & SD_BALANCE_WAKE) {
4270 if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
4276 for_each_domain(cpu, tmp) {
4277 if (!(tmp->flags & SD_LOAD_BALANCE))
4281 * If both cpu and prev_cpu are part of this domain,
4282 * cpu is a valid SD_WAKE_AFFINE target.
4284 if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
4285 cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
4290 if (tmp->flags & sd_flag)
4295 if (cpu != prev_cpu && wake_affine(affine_sd, p, sync))
4298 new_cpu = select_idle_sibling(p, prev_cpu);
4303 int load_idx = sd->forkexec_idx;
4304 struct sched_group *group;
4307 if (!(sd->flags & sd_flag)) {
4312 if (sd_flag & SD_BALANCE_WAKE)
4313 load_idx = sd->wake_idx;
4315 group = find_idlest_group(sd, p, cpu, load_idx);
4321 new_cpu = find_idlest_cpu(group, p, cpu);
4322 if (new_cpu == -1 || new_cpu == cpu) {
4323 /* Now try balancing at a lower domain level of cpu */
4328 /* Now try balancing at a lower domain level of new_cpu */
4330 weight = sd->span_weight;
4332 for_each_domain(cpu, tmp) {
4333 if (weight <= tmp->span_weight)
4335 if (tmp->flags & sd_flag)
4338 /* while loop will break here if sd == NULL */
4343 #ifdef CONFIG_SCHED_HMP
4344 prev_cpu = task_cpu(p);
4346 if (hmp_up_migration(prev_cpu, &new_cpu, &p->se)) {
4347 hmp_next_up_delay(&p->se, new_cpu);
4348 trace_sched_hmp_migrate(p, new_cpu, HMP_MIGRATE_WAKEUP);
4351 if (hmp_down_migration(prev_cpu, &p->se)) {
4352 #ifdef CONFIG_SCHED_HMP_LITTLE_PACKING
4353 new_cpu = hmp_best_little_cpu(p, prev_cpu);
4355 new_cpu = hmp_select_slower_cpu(p, prev_cpu);
4357 if (new_cpu != prev_cpu) {
4358 hmp_next_down_delay(&p->se, new_cpu);
4359 trace_sched_hmp_migrate(p, new_cpu, HMP_MIGRATE_WAKEUP);
4363 /* Make sure that the task stays in its previous hmp domain */
4364 if (!cpumask_test_cpu(new_cpu, &hmp_cpu_domain(prev_cpu)->cpus))
4372 * Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
4373 * removed when useful for applications beyond shares distribution (e.g.
4376 #ifdef CONFIG_FAIR_GROUP_SCHED
4378 #ifdef CONFIG_NO_HZ_COMMON
4379 static int nohz_test_cpu(int cpu);
4381 static inline int nohz_test_cpu(int cpu)
4388 * Called immediately before a task is migrated to a new cpu; task_cpu(p) and
4389 * cfs_rq_of(p) references at time of call are still valid and identify the
4390 * previous cpu. However, the caller only guarantees p->pi_lock is held; no
4391 * other assumptions, including the state of rq->lock, should be made.
4394 migrate_task_rq_fair(struct task_struct *p, int next_cpu)
4396 struct sched_entity *se = &p->se;
4397 struct cfs_rq *cfs_rq = cfs_rq_of(se);
4400 * Load tracking: accumulate removed load so that it can be processed
4401 * when we next update owning cfs_rq under rq->lock. Tasks contribute
4402 * to blocked load iff they have a positive decay-count. It can never
4403 * be negative here since on-rq tasks have decay-count == 0.
4405 if (se->avg.decay_count) {
4407 * If we migrate a sleeping task away from a CPU
4408 * which has the tick stopped, then both the clock_task
4409 * and decay_counter will be out of date for that CPU
4410 * and we will not decay load correctly.
4412 if (!se->on_rq && nohz_test_cpu(task_cpu(p))) {
4413 struct rq *rq = cpu_rq(task_cpu(p));
4414 unsigned long flags;
4416 * Current CPU cannot be holding rq->lock in this
4417 * circumstance, but another might be. We must hold
4418 * rq->lock before we go poking around in its clocks
4420 raw_spin_lock_irqsave(&rq->lock, flags);
4421 update_rq_clock(rq);
4422 update_cfs_rq_blocked_load(cfs_rq, 0);
4423 raw_spin_unlock_irqrestore(&rq->lock, flags);
4425 se->avg.decay_count = -__synchronize_entity_decay(se);
4426 atomic64_add(se->avg.load_avg_contrib, &cfs_rq->removed_load);
4430 #endif /* CONFIG_SMP */
4432 static unsigned long
4433 wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
4435 unsigned long gran = sysctl_sched_wakeup_granularity;
4438 * Since its curr running now, convert the gran from real-time
4439 * to virtual-time in his units.
4441 * By using 'se' instead of 'curr' we penalize light tasks, so
4442 * they get preempted easier. That is, if 'se' < 'curr' then
4443 * the resulting gran will be larger, therefore penalizing the
4444 * lighter, if otoh 'se' > 'curr' then the resulting gran will
4445 * be smaller, again penalizing the lighter task.
4447 * This is especially important for buddies when the leftmost
4448 * task is higher priority than the buddy.
4450 return calc_delta_fair(gran, se);
4454 * Should 'se' preempt 'curr'.
4468 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
4470 s64 gran, vdiff = curr->vruntime - se->vruntime;
4475 gran = wakeup_gran(curr, se);
4482 static void set_last_buddy(struct sched_entity *se)
4484 if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
4487 for_each_sched_entity(se)
4488 cfs_rq_of(se)->last = se;
4491 static void set_next_buddy(struct sched_entity *se)
4493 if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
4496 for_each_sched_entity(se)
4497 cfs_rq_of(se)->next = se;
4500 static void set_skip_buddy(struct sched_entity *se)
4502 for_each_sched_entity(se)
4503 cfs_rq_of(se)->skip = se;
4507 * Preempt the current task with a newly woken task if needed:
4509 static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
4511 struct task_struct *curr = rq->curr;
4512 struct sched_entity *se = &curr->se, *pse = &p->se;
4513 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
4514 int scale = cfs_rq->nr_running >= sched_nr_latency;
4515 int next_buddy_marked = 0;
4517 if (unlikely(se == pse))
4521 * This is possible from callers such as move_task(), in which we
4522 * unconditionally check_prempt_curr() after an enqueue (which may have
4523 * lead to a throttle). This both saves work and prevents false
4524 * next-buddy nomination below.
4526 if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
4529 if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
4530 set_next_buddy(pse);
4531 next_buddy_marked = 1;
4535 * We can come here with TIF_NEED_RESCHED already set from new task
4538 * Note: this also catches the edge-case of curr being in a throttled
4539 * group (e.g. via set_curr_task), since update_curr() (in the
4540 * enqueue of curr) will have resulted in resched being set. This
4541 * prevents us from potentially nominating it as a false LAST_BUDDY
4544 if (test_tsk_need_resched(curr))
4547 /* Idle tasks are by definition preempted by non-idle tasks. */
4548 if (unlikely(curr->policy == SCHED_IDLE) &&
4549 likely(p->policy != SCHED_IDLE))
4553 * Batch and idle tasks do not preempt non-idle tasks (their preemption
4554 * is driven by the tick):
4556 if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
4559 find_matching_se(&se, &pse);
4560 update_curr(cfs_rq_of(se));
4562 if (wakeup_preempt_entity(se, pse) == 1) {
4564 * Bias pick_next to pick the sched entity that is
4565 * triggering this preemption.
4567 if (!next_buddy_marked)
4568 set_next_buddy(pse);
4577 * Only set the backward buddy when the current task is still
4578 * on the rq. This can happen when a wakeup gets interleaved
4579 * with schedule on the ->pre_schedule() or idle_balance()
4580 * point, either of which can * drop the rq lock.
4582 * Also, during early boot the idle thread is in the fair class,
4583 * for obvious reasons its a bad idea to schedule back to it.
4585 if (unlikely(!se->on_rq || curr == rq->idle))
4588 if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
4592 static struct task_struct *pick_next_task_fair(struct rq *rq)
4594 struct task_struct *p;
4595 struct cfs_rq *cfs_rq = &rq->cfs;
4596 struct sched_entity *se;
4598 if (!cfs_rq->nr_running)
4602 se = pick_next_entity(cfs_rq);
4603 set_next_entity(cfs_rq, se);
4604 cfs_rq = group_cfs_rq(se);
4608 if (hrtick_enabled(rq))
4609 hrtick_start_fair(rq, p);
4615 * Account for a descheduled task:
4617 static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
4619 struct sched_entity *se = &prev->se;
4620 struct cfs_rq *cfs_rq;
4622 for_each_sched_entity(se) {
4623 cfs_rq = cfs_rq_of(se);
4624 put_prev_entity(cfs_rq, se);
4629 * sched_yield() is very simple
4631 * The magic of dealing with the ->skip buddy is in pick_next_entity.
4633 static void yield_task_fair(struct rq *rq)
4635 struct task_struct *curr = rq->curr;
4636 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
4637 struct sched_entity *se = &curr->se;
4640 * Are we the only task in the tree?
4642 if (unlikely(rq->nr_running == 1))
4645 clear_buddies(cfs_rq, se);
4647 if (curr->policy != SCHED_BATCH) {
4648 update_rq_clock(rq);
4650 * Update run-time statistics of the 'current'.
4652 update_curr(cfs_rq);
4654 * Tell update_rq_clock() that we've just updated,
4655 * so we don't do microscopic update in schedule()
4656 * and double the fastpath cost.
4658 rq->skip_clock_update = 1;
4664 static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt)
4666 struct sched_entity *se = &p->se;
4668 /* throttled hierarchies are not runnable */
4669 if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
4672 /* Tell the scheduler that we'd really like pse to run next. */
4675 yield_task_fair(rq);
4681 /**************************************************
4682 * Fair scheduling class load-balancing methods.
4686 * The purpose of load-balancing is to achieve the same basic fairness the
4687 * per-cpu scheduler provides, namely provide a proportional amount of compute
4688 * time to each task. This is expressed in the following equation:
4690 * W_i,n/P_i == W_j,n/P_j for all i,j (1)
4692 * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight
4693 * W_i,0 is defined as:
4695 * W_i,0 = \Sum_j w_i,j (2)
4697 * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight
4698 * is derived from the nice value as per prio_to_weight[].
4700 * The weight average is an exponential decay average of the instantaneous
4703 * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3)
4705 * P_i is the cpu power (or compute capacity) of cpu i, typically it is the
4706 * fraction of 'recent' time available for SCHED_OTHER task execution. But it
4707 * can also include other factors [XXX].
4709 * To achieve this balance we define a measure of imbalance which follows
4710 * directly from (1):
4712 * imb_i,j = max{ avg(W/P), W_i/P_i } - min{ avg(W/P), W_j/P_j } (4)
4714 * We them move tasks around to minimize the imbalance. In the continuous
4715 * function space it is obvious this converges, in the discrete case we get
4716 * a few fun cases generally called infeasible weight scenarios.
4719 * - infeasible weights;
4720 * - local vs global optima in the discrete case. ]
4725 * In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
4726 * for all i,j solution, we create a tree of cpus that follows the hardware
4727 * topology where each level pairs two lower groups (or better). This results
4728 * in O(log n) layers. Furthermore we reduce the number of cpus going up the
4729 * tree to only the first of the previous level and we decrease the frequency
4730 * of load-balance at each level inv. proportional to the number of cpus in
4736 * \Sum { --- * --- * 2^i } = O(n) (5)
4738 * `- size of each group
4739 * | | `- number of cpus doing load-balance
4741 * `- sum over all levels
4743 * Coupled with a limit on how many tasks we can migrate every balance pass,
4744 * this makes (5) the runtime complexity of the balancer.
4746 * An important property here is that each CPU is still (indirectly) connected
4747 * to every other cpu in at most O(log n) steps:
4749 * The adjacency matrix of the resulting graph is given by:
4752 * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6)
4755 * And you'll find that:
4757 * A^(log_2 n)_i,j != 0 for all i,j (7)
4759 * Showing there's indeed a path between every cpu in at most O(log n) steps.
4760 * The task movement gives a factor of O(m), giving a convergence complexity
4763 * O(nm log n), n := nr_cpus, m := nr_tasks (8)
4768 * In order to avoid CPUs going idle while there's still work to do, new idle
4769 * balancing is more aggressive and has the newly idle cpu iterate up the domain
4770 * tree itself instead of relying on other CPUs to bring it work.
4772 * This adds some complexity to both (5) and (8) but it reduces the total idle
4780 * Cgroups make a horror show out of (2), instead of a simple sum we get:
4783 * W_i,0 = \Sum_j \Prod_k w_k * ----- (9)
4788 * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10)
4790 * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i.
4792 * The big problem is S_k, its a global sum needed to compute a local (W_i)
4795 * [XXX write more on how we solve this.. _after_ merging pjt's patches that
4796 * rewrite all of this once again.]
4799 static unsigned long __read_mostly max_load_balance_interval = HZ/10;
4801 #define LBF_ALL_PINNED 0x01
4802 #define LBF_NEED_BREAK 0x02
4803 #define LBF_SOME_PINNED 0x04
4806 struct sched_domain *sd;
4814 struct cpumask *dst_grpmask;
4816 enum cpu_idle_type idle;
4818 /* The set of CPUs under consideration for load-balancing */
4819 struct cpumask *cpus;
4824 unsigned int loop_break;
4825 unsigned int loop_max;
4829 * move_task - move a task from one runqueue to another runqueue.
4830 * Both runqueues must be locked.
4832 static void move_task(struct task_struct *p, struct lb_env *env)
4834 deactivate_task(env->src_rq, p, 0);
4835 set_task_cpu(p, env->dst_cpu);
4836 activate_task(env->dst_rq, p, 0);
4837 check_preempt_curr(env->dst_rq, p, 0);
4841 * Is this task likely cache-hot:
4844 task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
4848 if (p->sched_class != &fair_sched_class)
4851 if (unlikely(p->policy == SCHED_IDLE))
4855 * Buddy candidates are cache hot:
4857 if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running &&
4858 (&p->se == cfs_rq_of(&p->se)->next ||
4859 &p->se == cfs_rq_of(&p->se)->last))
4862 if (sysctl_sched_migration_cost == -1)
4864 if (sysctl_sched_migration_cost == 0)
4867 delta = now - p->se.exec_start;
4869 return delta < (s64)sysctl_sched_migration_cost;
4873 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
4876 int can_migrate_task(struct task_struct *p, struct lb_env *env)
4878 int tsk_cache_hot = 0;
4880 * We do not migrate tasks that are:
4881 * 1) throttled_lb_pair, or
4882 * 2) cannot be migrated to this CPU due to cpus_allowed, or
4883 * 3) running (obviously), or
4884 * 4) are cache-hot on their current CPU.
4886 if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
4889 if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
4892 schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
4895 * Remember if this task can be migrated to any other cpu in
4896 * our sched_group. We may want to revisit it if we couldn't
4897 * meet load balance goals by pulling other tasks on src_cpu.
4899 * Also avoid computing new_dst_cpu if we have already computed
4900 * one in current iteration.
4902 if (!env->dst_grpmask || (env->flags & LBF_SOME_PINNED))
4905 /* Prevent to re-select dst_cpu via env's cpus */
4906 for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) {
4907 if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) {
4908 env->flags |= LBF_SOME_PINNED;
4909 env->new_dst_cpu = cpu;
4917 /* Record that we found atleast one task that could run on dst_cpu */
4918 env->flags &= ~LBF_ALL_PINNED;
4920 if (task_running(env->src_rq, p)) {
4921 schedstat_inc(p, se.statistics.nr_failed_migrations_running);
4926 * Aggressive migration if:
4927 * 1) task is cache cold, or
4928 * 2) too many balance attempts have failed.
4930 tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
4931 if (!tsk_cache_hot ||
4932 env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
4934 if (tsk_cache_hot) {
4935 schedstat_inc(env->sd, lb_hot_gained[env->idle]);
4936 schedstat_inc(p, se.statistics.nr_forced_migrations);
4942 schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
4947 * move_one_task tries to move exactly one task from busiest to this_rq, as
4948 * part of active balancing operations within "domain".
4949 * Returns 1 if successful and 0 otherwise.
4951 * Called with both runqueues locked.
4953 static int move_one_task(struct lb_env *env)
4955 struct task_struct *p, *n;
4957 list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
4958 if (!can_migrate_task(p, env))
4963 * Right now, this is only the second place move_task()
4964 * is called, so we can safely collect move_task()
4965 * stats here rather than inside move_task().
4967 schedstat_inc(env->sd, lb_gained[env->idle]);
4973 static unsigned long task_h_load(struct task_struct *p);
4975 static const unsigned int sched_nr_migrate_break = 32;
4978 * move_tasks tries to move up to imbalance weighted load from busiest to
4979 * this_rq, as part of a balancing operation within domain "sd".
4980 * Returns 1 if successful and 0 otherwise.
4982 * Called with both runqueues locked.
4984 static int move_tasks(struct lb_env *env)
4986 struct list_head *tasks = &env->src_rq->cfs_tasks;
4987 struct task_struct *p;
4991 if (env->imbalance <= 0)
4994 while (!list_empty(tasks)) {
4995 p = list_first_entry(tasks, struct task_struct, se.group_node);
4998 /* We've more or less seen every task there is, call it quits */
4999 if (env->loop > env->loop_max)
5002 /* take a breather every nr_migrate tasks */
5003 if (env->loop > env->loop_break) {
5004 env->loop_break += sched_nr_migrate_break;
5005 env->flags |= LBF_NEED_BREAK;
5009 if (!can_migrate_task(p, env))
5012 load = task_h_load(p);
5014 if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed)
5017 if ((load / 2) > env->imbalance)
5022 env->imbalance -= load;
5024 #ifdef CONFIG_PREEMPT
5026 * NEWIDLE balancing is a source of latency, so preemptible
5027 * kernels will stop after the first task is pulled to minimize
5028 * the critical section.
5030 if (env->idle == CPU_NEWLY_IDLE)
5035 * We only want to steal up to the prescribed amount of
5038 if (env->imbalance <= 0)
5043 list_move_tail(&p->se.group_node, tasks);
5047 * Right now, this is one of only two places move_task() is called,
5048 * so we can safely collect move_task() stats here rather than
5049 * inside move_task().
5051 schedstat_add(env->sd, lb_gained[env->idle], pulled);
5056 #ifdef CONFIG_FAIR_GROUP_SCHED
5058 * update tg->load_weight by folding this cpu's load_avg
5060 static void __update_blocked_averages_cpu(struct task_group *tg, int cpu)
5062 struct sched_entity *se = tg->se[cpu];
5063 struct cfs_rq *cfs_rq = tg->cfs_rq[cpu];
5065 /* throttled entities do not contribute to load */
5066 if (throttled_hierarchy(cfs_rq))
5069 update_cfs_rq_blocked_load(cfs_rq, 1);
5072 update_entity_load_avg(se, 1);
5074 * We pivot on our runnable average having decayed to zero for
5075 * list removal. This generally implies that all our children
5076 * have also been removed (modulo rounding error or bandwidth
5077 * control); however, such cases are rare and we can fix these
5080 * TODO: fix up out-of-order children on enqueue.
5082 if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running)
5083 list_del_leaf_cfs_rq(cfs_rq);
5085 struct rq *rq = rq_of(cfs_rq);
5086 update_rq_runnable_avg(rq, rq->nr_running);
5090 static void update_blocked_averages(int cpu)
5092 struct rq *rq = cpu_rq(cpu);
5093 struct cfs_rq *cfs_rq;
5094 unsigned long flags;
5096 raw_spin_lock_irqsave(&rq->lock, flags);
5097 update_rq_clock(rq);
5099 * Iterates the task_group tree in a bottom up fashion, see
5100 * list_add_leaf_cfs_rq() for details.
5102 for_each_leaf_cfs_rq(rq, cfs_rq) {
5104 * Note: We may want to consider periodically releasing
5105 * rq->lock about these updates so that creating many task
5106 * groups does not result in continually extending hold time.
5108 __update_blocked_averages_cpu(cfs_rq->tg, rq->cpu);
5111 raw_spin_unlock_irqrestore(&rq->lock, flags);
5115 * Compute the cpu's hierarchical load factor for each task group.
5116 * This needs to be done in a top-down fashion because the load of a child
5117 * group is a fraction of its parents load.
5119 static int tg_load_down(struct task_group *tg, void *data)
5122 long cpu = (long)data;
5125 load = cpu_rq(cpu)->load.weight;
5127 load = tg->parent->cfs_rq[cpu]->h_load;
5128 load *= tg->se[cpu]->load.weight;
5129 load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
5132 tg->cfs_rq[cpu]->h_load = load;
5137 static void update_h_load(long cpu)
5139 struct rq *rq = cpu_rq(cpu);
5140 unsigned long now = jiffies;
5142 if (rq->h_load_throttle == now)
5145 rq->h_load_throttle = now;
5148 walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
5152 static unsigned long task_h_load(struct task_struct *p)
5154 struct cfs_rq *cfs_rq = task_cfs_rq(p);
5157 load = p->se.load.weight;
5158 load = div_u64(load * cfs_rq->h_load, cfs_rq->load.weight + 1);
5163 static inline void update_blocked_averages(int cpu)
5167 static inline void update_h_load(long cpu)
5171 static unsigned long task_h_load(struct task_struct *p)
5173 return p->se.load.weight;
5177 /********** Helpers for find_busiest_group ************************/
5179 * sd_lb_stats - Structure to store the statistics of a sched_domain
5180 * during load balancing.
5182 struct sd_lb_stats {
5183 struct sched_group *busiest; /* Busiest group in this sd */
5184 struct sched_group *this; /* Local group in this sd */
5185 unsigned long total_load; /* Total load of all groups in sd */
5186 unsigned long total_pwr; /* Total power of all groups in sd */
5187 unsigned long avg_load; /* Average load across all groups in sd */
5189 /** Statistics of this group */
5190 unsigned long this_load;
5191 unsigned long this_load_per_task;
5192 unsigned long this_nr_running;
5193 unsigned long this_has_capacity;
5194 unsigned int this_idle_cpus;
5196 /* Statistics of the busiest group */
5197 unsigned int busiest_idle_cpus;
5198 unsigned long max_load;
5199 unsigned long busiest_load_per_task;
5200 unsigned long busiest_nr_running;
5201 unsigned long busiest_group_capacity;
5202 unsigned long busiest_has_capacity;
5203 unsigned int busiest_group_weight;
5205 int group_imb; /* Is there imbalance in this sd */
5209 * sg_lb_stats - stats of a sched_group required for load_balancing
5211 struct sg_lb_stats {
5212 unsigned long avg_load; /*Avg load across the CPUs of the group */
5213 unsigned long group_load; /* Total load over the CPUs of the group */
5214 unsigned long sum_nr_running; /* Nr tasks running in the group */
5215 unsigned long sum_weighted_load; /* Weighted load of group's tasks */
5216 unsigned long group_capacity;
5217 unsigned long idle_cpus;
5218 unsigned long group_weight;
5219 int group_imb; /* Is there an imbalance in the group ? */
5220 int group_has_capacity; /* Is there extra capacity in the group? */
5224 * get_sd_load_idx - Obtain the load index for a given sched domain.
5225 * @sd: The sched_domain whose load_idx is to be obtained.
5226 * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
5228 static inline int get_sd_load_idx(struct sched_domain *sd,
5229 enum cpu_idle_type idle)
5235 load_idx = sd->busy_idx;
5238 case CPU_NEWLY_IDLE:
5239 load_idx = sd->newidle_idx;
5242 load_idx = sd->idle_idx;
5249 static unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
5251 return SCHED_POWER_SCALE;
5254 unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
5256 return default_scale_freq_power(sd, cpu);
5259 static unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
5261 unsigned long weight = sd->span_weight;
5262 unsigned long smt_gain = sd->smt_gain;
5269 unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
5271 return default_scale_smt_power(sd, cpu);
5274 static unsigned long scale_rt_power(int cpu)
5276 struct rq *rq = cpu_rq(cpu);
5277 u64 total, available, age_stamp, avg;
5280 * Since we're reading these variables without serialization make sure
5281 * we read them once before doing sanity checks on them.
5283 age_stamp = ACCESS_ONCE(rq->age_stamp);
5284 avg = ACCESS_ONCE(rq->rt_avg);
5286 total = sched_avg_period() + (rq->clock - age_stamp);
5288 if (unlikely(total < avg)) {
5289 /* Ensures that power won't end up being negative */
5292 available = total - avg;
5295 if (unlikely((s64)total < SCHED_POWER_SCALE))
5296 total = SCHED_POWER_SCALE;
5298 total >>= SCHED_POWER_SHIFT;
5300 return div_u64(available, total);
5303 static void update_cpu_power(struct sched_domain *sd, int cpu)
5305 unsigned long weight = sd->span_weight;
5306 unsigned long power = SCHED_POWER_SCALE;
5307 struct sched_group *sdg = sd->groups;
5309 if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
5310 if (sched_feat(ARCH_POWER))
5311 power *= arch_scale_smt_power(sd, cpu);
5313 power *= default_scale_smt_power(sd, cpu);
5315 power >>= SCHED_POWER_SHIFT;
5318 sdg->sgp->power_orig = power;
5320 if (sched_feat(ARCH_POWER))
5321 power *= arch_scale_freq_power(sd, cpu);
5323 power *= default_scale_freq_power(sd, cpu);
5325 power >>= SCHED_POWER_SHIFT;
5327 power *= scale_rt_power(cpu);
5328 power >>= SCHED_POWER_SHIFT;
5333 cpu_rq(cpu)->cpu_power = power;
5334 sdg->sgp->power = power;
5337 void update_group_power(struct sched_domain *sd, int cpu)
5339 struct sched_domain *child = sd->child;
5340 struct sched_group *group, *sdg = sd->groups;
5341 unsigned long power;
5342 unsigned long interval;
5344 interval = msecs_to_jiffies(sd->balance_interval);
5345 interval = clamp(interval, 1UL, max_load_balance_interval);
5346 sdg->sgp->next_update = jiffies + interval;
5349 update_cpu_power(sd, cpu);
5355 if (child->flags & SD_OVERLAP) {
5357 * SD_OVERLAP domains cannot assume that child groups
5358 * span the current group.
5361 for_each_cpu(cpu, sched_group_cpus(sdg))
5362 power += power_of(cpu);
5365 * !SD_OVERLAP domains can assume that child groups
5366 * span the current group.
5369 group = child->groups;
5371 power += group->sgp->power;
5372 group = group->next;
5373 } while (group != child->groups);
5376 sdg->sgp->power_orig = sdg->sgp->power = power;
5380 * Try and fix up capacity for tiny siblings, this is needed when
5381 * things like SD_ASYM_PACKING need f_b_g to select another sibling
5382 * which on its own isn't powerful enough.
5384 * See update_sd_pick_busiest() and check_asym_packing().
5387 fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
5390 * Only siblings can have significantly less than SCHED_POWER_SCALE
5392 if (!(sd->flags & SD_SHARE_CPUPOWER))
5396 * If ~90% of the cpu_power is still there, we're good.
5398 if (group->sgp->power * 32 > group->sgp->power_orig * 29)
5405 * update_sg_lb_stats - Update sched_group's statistics for load balancing.
5406 * @env: The load balancing environment.
5407 * @group: sched_group whose statistics are to be updated.
5408 * @load_idx: Load index of sched_domain of this_cpu for load calc.
5409 * @local_group: Does group contain this_cpu.
5410 * @balance: Should we balance.
5411 * @sgs: variable to hold the statistics for this group.
5413 static inline void update_sg_lb_stats(struct lb_env *env,
5414 struct sched_group *group, int load_idx,
5415 int local_group, int *balance, struct sg_lb_stats *sgs)
5417 unsigned long nr_running, max_nr_running, min_nr_running;
5418 unsigned long load, max_cpu_load, min_cpu_load;
5419 unsigned int balance_cpu = -1, first_idle_cpu = 0;
5420 unsigned long avg_load_per_task = 0;
5424 balance_cpu = group_balance_cpu(group);
5426 /* Tally up the load of all CPUs in the group */
5428 min_cpu_load = ~0UL;
5430 min_nr_running = ~0UL;
5432 for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
5433 struct rq *rq = cpu_rq(i);
5435 nr_running = rq->nr_running;
5437 /* Bias balancing toward cpus of our domain */
5439 if (idle_cpu(i) && !first_idle_cpu &&
5440 cpumask_test_cpu(i, sched_group_mask(group))) {
5445 load = target_load(i, load_idx);
5447 load = source_load(i, load_idx);
5448 if (load > max_cpu_load)
5449 max_cpu_load = load;
5450 if (min_cpu_load > load)
5451 min_cpu_load = load;
5453 if (nr_running > max_nr_running)
5454 max_nr_running = nr_running;
5455 if (min_nr_running > nr_running)
5456 min_nr_running = nr_running;
5459 sgs->group_load += load;
5460 sgs->sum_nr_running += nr_running;
5461 sgs->sum_weighted_load += weighted_cpuload(i);
5467 * First idle cpu or the first cpu(busiest) in this sched group
5468 * is eligible for doing load balancing at this and above
5469 * domains. In the newly idle case, we will allow all the cpu's
5470 * to do the newly idle load balance.
5473 if (env->idle != CPU_NEWLY_IDLE) {
5474 if (balance_cpu != env->dst_cpu) {
5478 update_group_power(env->sd, env->dst_cpu);
5479 } else if (time_after_eq(jiffies, group->sgp->next_update))
5480 update_group_power(env->sd, env->dst_cpu);
5483 /* Adjust by relative CPU power of the group */
5484 sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;
5487 * Consider the group unbalanced when the imbalance is larger
5488 * than the average weight of a task.
5490 * APZ: with cgroup the avg task weight can vary wildly and
5491 * might not be a suitable number - should we keep a
5492 * normalized nr_running number somewhere that negates
5495 if (sgs->sum_nr_running)
5496 avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
5498 if ((max_cpu_load - min_cpu_load) >= avg_load_per_task &&
5499 (max_nr_running - min_nr_running) > 1)
5502 sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
5504 if (!sgs->group_capacity)
5505 sgs->group_capacity = fix_small_capacity(env->sd, group);
5506 sgs->group_weight = group->group_weight;
5508 if (sgs->group_capacity > sgs->sum_nr_running)
5509 sgs->group_has_capacity = 1;
5513 * update_sd_pick_busiest - return 1 on busiest group
5514 * @env: The load balancing environment.
5515 * @sds: sched_domain statistics
5516 * @sg: sched_group candidate to be checked for being the busiest
5517 * @sgs: sched_group statistics
5519 * Determine if @sg is a busier group than the previously selected
5522 static bool update_sd_pick_busiest(struct lb_env *env,
5523 struct sd_lb_stats *sds,
5524 struct sched_group *sg,
5525 struct sg_lb_stats *sgs)
5527 if (sgs->avg_load <= sds->max_load)
5530 if (sgs->sum_nr_running > sgs->group_capacity)
5537 * ASYM_PACKING needs to move all the work to the lowest
5538 * numbered CPUs in the group, therefore mark all groups
5539 * higher than ourself as busy.
5541 if ((env->sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running &&
5542 env->dst_cpu < group_first_cpu(sg)) {
5546 if (group_first_cpu(sds->busiest) > group_first_cpu(sg))
5554 * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
5555 * @env: The load balancing environment.
5556 * @balance: Should we balance.
5557 * @sds: variable to hold the statistics for this sched_domain.
5559 static inline void update_sd_lb_stats(struct lb_env *env,
5560 int *balance, struct sd_lb_stats *sds)
5562 struct sched_domain *child = env->sd->child;
5563 struct sched_group *sg = env->sd->groups;
5564 struct sg_lb_stats sgs;
5565 int load_idx, prefer_sibling = 0;
5567 if (child && child->flags & SD_PREFER_SIBLING)
5570 load_idx = get_sd_load_idx(env->sd, env->idle);
5575 local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg));
5576 memset(&sgs, 0, sizeof(sgs));
5577 update_sg_lb_stats(env, sg, load_idx, local_group, balance, &sgs);
5579 if (local_group && !(*balance))
5582 sds->total_load += sgs.group_load;
5583 sds->total_pwr += sg->sgp->power;
5586 * In case the child domain prefers tasks go to siblings
5587 * first, lower the sg capacity to one so that we'll try
5588 * and move all the excess tasks away. We lower the capacity
5589 * of a group only if the local group has the capacity to fit
5590 * these excess tasks, i.e. nr_running < group_capacity. The
5591 * extra check prevents the case where you always pull from the
5592 * heaviest group when it is already under-utilized (possible
5593 * with a large weight task outweighs the tasks on the system).
5595 if (prefer_sibling && !local_group && sds->this_has_capacity)
5596 sgs.group_capacity = min(sgs.group_capacity, 1UL);
5599 sds->this_load = sgs.avg_load;
5601 sds->this_nr_running = sgs.sum_nr_running;
5602 sds->this_load_per_task = sgs.sum_weighted_load;
5603 sds->this_has_capacity = sgs.group_has_capacity;
5604 sds->this_idle_cpus = sgs.idle_cpus;
5605 } else if (update_sd_pick_busiest(env, sds, sg, &sgs)) {
5606 sds->max_load = sgs.avg_load;
5608 sds->busiest_nr_running = sgs.sum_nr_running;
5609 sds->busiest_idle_cpus = sgs.idle_cpus;
5610 sds->busiest_group_capacity = sgs.group_capacity;
5611 sds->busiest_load_per_task = sgs.sum_weighted_load;
5612 sds->busiest_has_capacity = sgs.group_has_capacity;
5613 sds->busiest_group_weight = sgs.group_weight;
5614 sds->group_imb = sgs.group_imb;
5618 } while (sg != env->sd->groups);
5622 * check_asym_packing - Check to see if the group is packed into the
5625 * This is primarily intended to used at the sibling level. Some
5626 * cores like POWER7 prefer to use lower numbered SMT threads. In the
5627 * case of POWER7, it can move to lower SMT modes only when higher
5628 * threads are idle. When in lower SMT modes, the threads will
5629 * perform better since they share less core resources. Hence when we
5630 * have idle threads, we want them to be the higher ones.
5632 * This packing function is run on idle threads. It checks to see if
5633 * the busiest CPU in this domain (core in the P7 case) has a higher
5634 * CPU number than the packing function is being run on. Here we are
5635 * assuming lower CPU number will be equivalent to lower a SMT thread
5638 * Returns 1 when packing is required and a task should be moved to
5639 * this CPU. The amount of the imbalance is returned in *imbalance.
5641 * @env: The load balancing environment.
5642 * @sds: Statistics of the sched_domain which is to be packed
5644 static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
5648 if (!(env->sd->flags & SD_ASYM_PACKING))
5654 busiest_cpu = group_first_cpu(sds->busiest);
5655 if (env->dst_cpu > busiest_cpu)
5658 env->imbalance = DIV_ROUND_CLOSEST(
5659 sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE);
5665 * fix_small_imbalance - Calculate the minor imbalance that exists
5666 * amongst the groups of a sched_domain, during
5668 * @env: The load balancing environment.
5669 * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
5672 void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
5674 unsigned long tmp, pwr_now = 0, pwr_move = 0;
5675 unsigned int imbn = 2;
5676 unsigned long scaled_busy_load_per_task;
5678 if (sds->this_nr_running) {
5679 sds->this_load_per_task /= sds->this_nr_running;
5680 if (sds->busiest_load_per_task >
5681 sds->this_load_per_task)
5684 sds->this_load_per_task =
5685 cpu_avg_load_per_task(env->dst_cpu);
5688 scaled_busy_load_per_task = sds->busiest_load_per_task
5689 * SCHED_POWER_SCALE;
5690 scaled_busy_load_per_task /= sds->busiest->sgp->power;
5692 if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
5693 (scaled_busy_load_per_task * imbn)) {
5694 env->imbalance = sds->busiest_load_per_task;
5699 * OK, we don't have enough imbalance to justify moving tasks,
5700 * however we may be able to increase total CPU power used by
5704 pwr_now += sds->busiest->sgp->power *
5705 min(sds->busiest_load_per_task, sds->max_load);
5706 pwr_now += sds->this->sgp->power *
5707 min(sds->this_load_per_task, sds->this_load);
5708 pwr_now /= SCHED_POWER_SCALE;
5710 /* Amount of load we'd subtract */
5711 tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
5712 sds->busiest->sgp->power;
5713 if (sds->max_load > tmp)
5714 pwr_move += sds->busiest->sgp->power *
5715 min(sds->busiest_load_per_task, sds->max_load - tmp);
5717 /* Amount of load we'd add */
5718 if (sds->max_load * sds->busiest->sgp->power <
5719 sds->busiest_load_per_task * SCHED_POWER_SCALE)
5720 tmp = (sds->max_load * sds->busiest->sgp->power) /
5721 sds->this->sgp->power;
5723 tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
5724 sds->this->sgp->power;
5725 pwr_move += sds->this->sgp->power *
5726 min(sds->this_load_per_task, sds->this_load + tmp);
5727 pwr_move /= SCHED_POWER_SCALE;
5729 /* Move if we gain throughput */
5730 if (pwr_move > pwr_now)
5731 env->imbalance = sds->busiest_load_per_task;
5735 * calculate_imbalance - Calculate the amount of imbalance present within the
5736 * groups of a given sched_domain during load balance.
5737 * @env: load balance environment
5738 * @sds: statistics of the sched_domain whose imbalance is to be calculated.
5740 static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
5742 unsigned long max_pull, load_above_capacity = ~0UL;
5744 sds->busiest_load_per_task /= sds->busiest_nr_running;
5745 if (sds->group_imb) {
5746 sds->busiest_load_per_task =
5747 min(sds->busiest_load_per_task, sds->avg_load);
5751 * In the presence of smp nice balancing, certain scenarios can have
5752 * max load less than avg load(as we skip the groups at or below
5753 * its cpu_power, while calculating max_load..)
5755 if (sds->max_load < sds->avg_load) {
5757 return fix_small_imbalance(env, sds);
5760 if (!sds->group_imb) {
5762 * Don't want to pull so many tasks that a group would go idle.
5764 load_above_capacity = (sds->busiest_nr_running -
5765 sds->busiest_group_capacity);
5767 load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
5769 load_above_capacity /= sds->busiest->sgp->power;
5773 * We're trying to get all the cpus to the average_load, so we don't
5774 * want to push ourselves above the average load, nor do we wish to
5775 * reduce the max loaded cpu below the average load. At the same time,
5776 * we also don't want to reduce the group load below the group capacity
5777 * (so that we can implement power-savings policies etc). Thus we look
5778 * for the minimum possible imbalance.
5779 * Be careful of negative numbers as they'll appear as very large values
5780 * with unsigned longs.
5782 max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);
5784 /* How much load to actually move to equalise the imbalance */
5785 env->imbalance = min(max_pull * sds->busiest->sgp->power,
5786 (sds->avg_load - sds->this_load) * sds->this->sgp->power)
5787 / SCHED_POWER_SCALE;
5790 * if *imbalance is less than the average load per runnable task
5791 * there is no guarantee that any tasks will be moved so we'll have
5792 * a think about bumping its value to force at least one task to be
5795 if (env->imbalance < sds->busiest_load_per_task)
5796 return fix_small_imbalance(env, sds);
5800 /******* find_busiest_group() helpers end here *********************/
5803 * find_busiest_group - Returns the busiest group within the sched_domain
5804 * if there is an imbalance. If there isn't an imbalance, and
5805 * the user has opted for power-savings, it returns a group whose
5806 * CPUs can be put to idle by rebalancing those tasks elsewhere, if
5807 * such a group exists.
5809 * Also calculates the amount of weighted load which should be moved
5810 * to restore balance.
5812 * @env: The load balancing environment.
5813 * @balance: Pointer to a variable indicating if this_cpu
5814 * is the appropriate cpu to perform load balancing at this_level.
5816 * Returns: - the busiest group if imbalance exists.
5817 * - If no imbalance and user has opted for power-savings balance,
5818 * return the least loaded group whose CPUs can be
5819 * put to idle by rebalancing its tasks onto our group.
5821 static struct sched_group *
5822 find_busiest_group(struct lb_env *env, int *balance)
5824 struct sd_lb_stats sds;
5826 memset(&sds, 0, sizeof(sds));
5829 * Compute the various statistics relavent for load balancing at
5832 update_sd_lb_stats(env, balance, &sds);
5835 * this_cpu is not the appropriate cpu to perform load balancing at
5841 if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) &&
5842 check_asym_packing(env, &sds))
5845 /* There is no busy sibling group to pull tasks from */
5846 if (!sds.busiest || sds.busiest_nr_running == 0)
5849 sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
5852 * If the busiest group is imbalanced the below checks don't
5853 * work because they assumes all things are equal, which typically
5854 * isn't true due to cpus_allowed constraints and the like.
5859 /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
5860 if (env->idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
5861 !sds.busiest_has_capacity)
5865 * If the local group is more busy than the selected busiest group
5866 * don't try and pull any tasks.
5868 if (sds.this_load >= sds.max_load)
5872 * Don't pull any tasks if this group is already above the domain
5875 if (sds.this_load >= sds.avg_load)
5878 if (env->idle == CPU_IDLE) {
5880 * This cpu is idle. If the busiest group load doesn't
5881 * have more tasks than the number of available cpu's and
5882 * there is no imbalance between this and busiest group
5883 * wrt to idle cpu's, it is balanced.
5885 if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) &&
5886 sds.busiest_nr_running <= sds.busiest_group_weight)
5890 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
5891 * imbalance_pct to be conservative.
5893 if (100 * sds.max_load <= env->sd->imbalance_pct * sds.this_load)
5898 /* Looks like there is an imbalance. Compute it */
5899 calculate_imbalance(env, &sds);
5909 * find_busiest_queue - find the busiest runqueue among the cpus in group.
5911 static struct rq *find_busiest_queue(struct lb_env *env,
5912 struct sched_group *group)
5914 struct rq *busiest = NULL, *rq;
5915 unsigned long max_load = 0;
5918 for_each_cpu(i, sched_group_cpus(group)) {
5919 unsigned long power = power_of(i);
5920 unsigned long capacity = DIV_ROUND_CLOSEST(power,
5925 capacity = fix_small_capacity(env->sd, group);
5927 if (!cpumask_test_cpu(i, env->cpus))
5931 wl = weighted_cpuload(i);
5934 * When comparing with imbalance, use weighted_cpuload()
5935 * which is not scaled with the cpu power.
5937 if (capacity && rq->nr_running == 1 && wl > env->imbalance)
5941 * For the load comparisons with the other cpu's, consider
5942 * the weighted_cpuload() scaled with the cpu power, so that
5943 * the load can be moved away from the cpu that is potentially
5944 * running at a lower capacity.
5946 wl = (wl * SCHED_POWER_SCALE) / power;
5948 if (wl > max_load) {
5958 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
5959 * so long as it is large enough.
5961 #define MAX_PINNED_INTERVAL 512
5963 /* Working cpumask for load_balance and load_balance_newidle. */
5964 DEFINE_PER_CPU(cpumask_var_t, load_balance_mask);
5966 static int need_active_balance(struct lb_env *env)
5968 struct sched_domain *sd = env->sd;
5970 if (env->idle == CPU_NEWLY_IDLE) {
5973 * ASYM_PACKING needs to force migrate tasks from busy but
5974 * higher numbered CPUs in order to pack all tasks in the
5975 * lowest numbered CPUs.
5977 if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu)
5981 return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
5984 static int active_load_balance_cpu_stop(void *data);
5987 * Check this_cpu to ensure it is balanced within domain. Attempt to move
5988 * tasks if there is an imbalance.
5990 static int load_balance(int this_cpu, struct rq *this_rq,
5991 struct sched_domain *sd, enum cpu_idle_type idle,
5994 int ld_moved, cur_ld_moved, active_balance = 0;
5995 struct sched_group *group;
5997 unsigned long flags;
5998 struct cpumask *cpus = __get_cpu_var(load_balance_mask);
6000 struct lb_env env = {
6002 .dst_cpu = this_cpu,
6004 .dst_grpmask = sched_group_cpus(sd->groups),
6006 .loop_break = sched_nr_migrate_break,
6011 * For NEWLY_IDLE load_balancing, we don't need to consider
6012 * other cpus in our group
6014 if (idle == CPU_NEWLY_IDLE)
6015 env.dst_grpmask = NULL;
6017 cpumask_copy(cpus, cpu_active_mask);
6019 schedstat_inc(sd, lb_count[idle]);
6022 group = find_busiest_group(&env, balance);
6028 schedstat_inc(sd, lb_nobusyg[idle]);
6032 busiest = find_busiest_queue(&env, group);
6034 schedstat_inc(sd, lb_nobusyq[idle]);
6038 BUG_ON(busiest == env.dst_rq);
6040 schedstat_add(sd, lb_imbalance[idle], env.imbalance);
6043 if (busiest->nr_running > 1) {
6045 * Attempt to move tasks. If find_busiest_group has found
6046 * an imbalance but busiest->nr_running <= 1, the group is
6047 * still unbalanced. ld_moved simply stays zero, so it is
6048 * correctly treated as an imbalance.
6050 env.flags |= LBF_ALL_PINNED;
6051 env.src_cpu = busiest->cpu;
6052 env.src_rq = busiest;
6053 env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running);
6055 update_h_load(env.src_cpu);
6057 local_irq_save(flags);
6058 double_rq_lock(env.dst_rq, busiest);
6061 * cur_ld_moved - load moved in current iteration
6062 * ld_moved - cumulative load moved across iterations
6064 cur_ld_moved = move_tasks(&env);
6065 ld_moved += cur_ld_moved;
6066 double_rq_unlock(env.dst_rq, busiest);
6067 local_irq_restore(flags);
6070 * some other cpu did the load balance for us.
6072 if (cur_ld_moved && env.dst_cpu != smp_processor_id())
6073 resched_cpu(env.dst_cpu);
6075 if (env.flags & LBF_NEED_BREAK) {
6076 env.flags &= ~LBF_NEED_BREAK;
6081 * Revisit (affine) tasks on src_cpu that couldn't be moved to
6082 * us and move them to an alternate dst_cpu in our sched_group
6083 * where they can run. The upper limit on how many times we
6084 * iterate on same src_cpu is dependent on number of cpus in our
6087 * This changes load balance semantics a bit on who can move
6088 * load to a given_cpu. In addition to the given_cpu itself
6089 * (or a ilb_cpu acting on its behalf where given_cpu is
6090 * nohz-idle), we now have balance_cpu in a position to move
6091 * load to given_cpu. In rare situations, this may cause
6092 * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
6093 * _independently_ and at _same_ time to move some load to
6094 * given_cpu) causing exceess load to be moved to given_cpu.
6095 * This however should not happen so much in practice and
6096 * moreover subsequent load balance cycles should correct the
6097 * excess load moved.
6099 if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) {
6101 env.dst_rq = cpu_rq(env.new_dst_cpu);
6102 env.dst_cpu = env.new_dst_cpu;
6103 env.flags &= ~LBF_SOME_PINNED;
6105 env.loop_break = sched_nr_migrate_break;
6107 /* Prevent to re-select dst_cpu via env's cpus */
6108 cpumask_clear_cpu(env.dst_cpu, env.cpus);
6111 * Go back to "more_balance" rather than "redo" since we
6112 * need to continue with same src_cpu.
6117 /* All tasks on this runqueue were pinned by CPU affinity */
6118 if (unlikely(env.flags & LBF_ALL_PINNED)) {
6119 cpumask_clear_cpu(cpu_of(busiest), cpus);
6120 if (!cpumask_empty(cpus)) {
6122 env.loop_break = sched_nr_migrate_break;
6130 schedstat_inc(sd, lb_failed[idle]);
6132 * Increment the failure counter only on periodic balance.
6133 * We do not want newidle balance, which can be very
6134 * frequent, pollute the failure counter causing
6135 * excessive cache_hot migrations and active balances.
6137 if (idle != CPU_NEWLY_IDLE)
6138 sd->nr_balance_failed++;
6140 if (need_active_balance(&env)) {
6141 raw_spin_lock_irqsave(&busiest->lock, flags);
6143 /* don't kick the active_load_balance_cpu_stop,
6144 * if the curr task on busiest cpu can't be
6147 if (!cpumask_test_cpu(this_cpu,
6148 tsk_cpus_allowed(busiest->curr))) {
6149 raw_spin_unlock_irqrestore(&busiest->lock,
6151 env.flags |= LBF_ALL_PINNED;
6152 goto out_one_pinned;
6156 * ->active_balance synchronizes accesses to
6157 * ->active_balance_work. Once set, it's cleared
6158 * only after active load balance is finished.
6160 if (!busiest->active_balance) {
6161 busiest->active_balance = 1;
6162 busiest->push_cpu = this_cpu;
6165 raw_spin_unlock_irqrestore(&busiest->lock, flags);
6167 if (active_balance) {
6168 stop_one_cpu_nowait(cpu_of(busiest),
6169 active_load_balance_cpu_stop, busiest,
6170 &busiest->active_balance_work);
6174 * We've kicked active balancing, reset the failure
6177 sd->nr_balance_failed = sd->cache_nice_tries+1;
6180 sd->nr_balance_failed = 0;
6182 if (likely(!active_balance)) {
6183 /* We were unbalanced, so reset the balancing interval */
6184 sd->balance_interval = sd->min_interval;
6187 * If we've begun active balancing, start to back off. This
6188 * case may not be covered by the all_pinned logic if there
6189 * is only 1 task on the busy runqueue (because we don't call
6192 if (sd->balance_interval < sd->max_interval)
6193 sd->balance_interval *= 2;
6199 schedstat_inc(sd, lb_balanced[idle]);
6201 sd->nr_balance_failed = 0;
6204 /* tune up the balancing interval */
6205 if (((env.flags & LBF_ALL_PINNED) &&
6206 sd->balance_interval < MAX_PINNED_INTERVAL) ||
6207 (sd->balance_interval < sd->max_interval))
6208 sd->balance_interval *= 2;
6214 #ifdef CONFIG_SCHED_HMP
6215 static unsigned int hmp_idle_pull(int this_cpu);
6218 * idle_balance is called by schedule() if this_cpu is about to become
6219 * idle. Attempts to pull tasks from other CPUs.
6221 void idle_balance(int this_cpu, struct rq *this_rq)
6223 struct sched_domain *sd;
6224 int pulled_task = 0;
6225 unsigned long next_balance = jiffies + HZ;
6227 this_rq->idle_stamp = this_rq->clock;
6229 if (this_rq->avg_idle < sysctl_sched_migration_cost)
6233 * Drop the rq->lock, but keep IRQ/preempt disabled.
6235 raw_spin_unlock(&this_rq->lock);
6237 update_blocked_averages(this_cpu);
6239 for_each_domain(this_cpu, sd) {
6240 unsigned long interval;
6243 if (!(sd->flags & SD_LOAD_BALANCE))
6246 if (sd->flags & SD_BALANCE_NEWIDLE) {
6247 /* If we've pulled tasks over stop searching: */
6248 pulled_task = load_balance(this_cpu, this_rq,
6249 sd, CPU_NEWLY_IDLE, &balance);
6252 interval = msecs_to_jiffies(sd->balance_interval);
6253 if (time_after(next_balance, sd->last_balance + interval))
6254 next_balance = sd->last_balance + interval;
6256 this_rq->idle_stamp = 0;
6261 #ifdef CONFIG_SCHED_HMP
6263 pulled_task = hmp_idle_pull(this_cpu);
6265 raw_spin_lock(&this_rq->lock);
6267 if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
6269 * We are going idle. next_balance may be set based on
6270 * a busy processor. So reset next_balance.
6272 this_rq->next_balance = next_balance;
6277 * active_load_balance_cpu_stop is run by cpu stopper. It pushes
6278 * running tasks off the busiest CPU onto idle CPUs. It requires at
6279 * least 1 task to be running on each physical CPU where possible, and
6280 * avoids physical / logical imbalances.
6282 static int active_load_balance_cpu_stop(void *data)
6284 struct rq *busiest_rq = data;
6285 int busiest_cpu = cpu_of(busiest_rq);
6286 int target_cpu = busiest_rq->push_cpu;
6287 struct rq *target_rq = cpu_rq(target_cpu);
6288 struct sched_domain *sd;
6290 raw_spin_lock_irq(&busiest_rq->lock);
6292 /* make sure the requested cpu hasn't gone down in the meantime */
6293 if (unlikely(busiest_cpu != smp_processor_id() ||
6294 !busiest_rq->active_balance))
6297 /* Is there any task to move? */
6298 if (busiest_rq->nr_running <= 1)
6302 * This condition is "impossible", if it occurs
6303 * we need to fix it. Originally reported by
6304 * Bjorn Helgaas on a 128-cpu setup.
6306 BUG_ON(busiest_rq == target_rq);
6308 /* move a task from busiest_rq to target_rq */
6309 double_lock_balance(busiest_rq, target_rq);
6311 /* Search for an sd spanning us and the target CPU. */
6313 for_each_domain(target_cpu, sd) {
6314 if ((sd->flags & SD_LOAD_BALANCE) &&
6315 cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
6320 struct lb_env env = {
6322 .dst_cpu = target_cpu,
6323 .dst_rq = target_rq,
6324 .src_cpu = busiest_rq->cpu,
6325 .src_rq = busiest_rq,
6329 schedstat_inc(sd, alb_count);
6331 if (move_one_task(&env))
6332 schedstat_inc(sd, alb_pushed);
6334 schedstat_inc(sd, alb_failed);
6337 double_unlock_balance(busiest_rq, target_rq);
6339 busiest_rq->active_balance = 0;
6340 raw_spin_unlock_irq(&busiest_rq->lock);
6344 #ifdef CONFIG_NO_HZ_COMMON
6346 * idle load balancing details
6347 * - When one of the busy CPUs notice that there may be an idle rebalancing
6348 * needed, they will kick the idle load balancer, which then does idle
6349 * load balancing for all the idle CPUs.
6352 cpumask_var_t idle_cpus_mask;
6354 unsigned long next_balance; /* in jiffy units */
6355 } nohz ____cacheline_aligned;
6358 * nohz_test_cpu used when load tracking is enabled. FAIR_GROUP_SCHED
6359 * dependency below may be removed when load tracking guards are
6362 #ifdef CONFIG_FAIR_GROUP_SCHED
6363 static int nohz_test_cpu(int cpu)
6365 return cpumask_test_cpu(cpu, nohz.idle_cpus_mask);
6369 #ifdef CONFIG_SCHED_HMP_LITTLE_PACKING
6371 * Decide if the tasks on the busy CPUs in the
6372 * littlest domain would benefit from an idle balance
6374 static int hmp_packing_ilb_needed(int cpu)
6376 struct hmp_domain *hmp;
6377 /* always allow ilb on non-slowest domain */
6378 if (!hmp_cpu_is_slowest(cpu))
6381 /* if disabled, use normal ILB behaviour */
6382 if (!hmp_packing_enabled)
6385 hmp = hmp_cpu_domain(cpu);
6386 for_each_cpu_and(cpu, &hmp->cpus, nohz.idle_cpus_mask) {
6387 /* only idle balance if a CPU is loaded over threshold */
6388 if (cpu_rq(cpu)->avg.load_avg_ratio > hmp_full_threshold)
6395 static inline int find_new_ilb(int call_cpu)
6397 int ilb = cpumask_first(nohz.idle_cpus_mask);
6398 #ifdef CONFIG_SCHED_HMP
6401 /* restrict nohz balancing to occur in the same hmp domain */
6402 ilb = cpumask_first_and(nohz.idle_cpus_mask,
6403 &((struct hmp_domain *)hmp_cpu_domain(call_cpu))->cpus);
6405 #ifdef CONFIG_SCHED_HMP_LITTLE_PACKING
6406 if (ilb < nr_cpu_ids)
6407 ilb_needed = hmp_packing_ilb_needed(ilb);
6410 if (ilb_needed && ilb < nr_cpu_ids && idle_cpu(ilb))
6413 if (ilb < nr_cpu_ids && idle_cpu(ilb))
6421 * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
6422 * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
6423 * CPU (if there is one).
6425 static void nohz_balancer_kick(int cpu)
6429 nohz.next_balance++;
6431 ilb_cpu = find_new_ilb(cpu);
6433 if (ilb_cpu >= nr_cpu_ids)
6436 if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu)))
6439 * Use smp_send_reschedule() instead of resched_cpu().
6440 * This way we generate a sched IPI on the target cpu which
6441 * is idle. And the softirq performing nohz idle load balance
6442 * will be run before returning from the IPI.
6444 smp_send_reschedule(ilb_cpu);
6448 static inline void nohz_balance_exit_idle(int cpu)
6450 if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
6451 cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
6452 atomic_dec(&nohz.nr_cpus);
6453 clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
6457 static inline void set_cpu_sd_state_busy(void)
6459 struct sched_domain *sd;
6460 int cpu = smp_processor_id();
6463 sd = rcu_dereference_check_sched_domain(cpu_rq(cpu)->sd);
6465 if (!sd || !sd->nohz_idle)
6469 for (; sd; sd = sd->parent)
6470 atomic_inc(&sd->groups->sgp->nr_busy_cpus);
6475 void set_cpu_sd_state_idle(void)
6477 struct sched_domain *sd;
6478 int cpu = smp_processor_id();
6481 sd = rcu_dereference_check_sched_domain(cpu_rq(cpu)->sd);
6483 if (!sd || sd->nohz_idle)
6487 for (; sd; sd = sd->parent)
6488 atomic_dec(&sd->groups->sgp->nr_busy_cpus);
6494 * This routine will record that the cpu is going idle with tick stopped.
6495 * This info will be used in performing idle load balancing in the future.
6497 void nohz_balance_enter_idle(int cpu)
6500 * If this cpu is going down, then nothing needs to be done.
6502 if (!cpu_active(cpu))
6505 if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
6508 cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
6509 atomic_inc(&nohz.nr_cpus);
6510 set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
6513 static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
6514 unsigned long action, void *hcpu)
6516 switch (action & ~CPU_TASKS_FROZEN) {
6518 nohz_balance_exit_idle(smp_processor_id());
6526 static DEFINE_SPINLOCK(balancing);
6529 * Scale the max load_balance interval with the number of CPUs in the system.
6530 * This trades load-balance latency on larger machines for less cross talk.
6532 void update_max_interval(void)
6534 max_load_balance_interval = HZ*num_online_cpus()/10;
6538 * It checks each scheduling domain to see if it is due to be balanced,
6539 * and initiates a balancing operation if so.
6541 * Balancing parameters are set up in init_sched_domains.
6543 static void rebalance_domains(int cpu, enum cpu_idle_type idle)
6546 struct rq *rq = cpu_rq(cpu);
6547 unsigned long interval;
6548 struct sched_domain *sd;
6549 /* Earliest time when we have to do rebalance again */
6550 unsigned long next_balance = jiffies + 60*HZ;
6551 int update_next_balance = 0;
6554 update_blocked_averages(cpu);
6557 for_each_domain(cpu, sd) {
6558 if (!(sd->flags & SD_LOAD_BALANCE))
6561 interval = sd->balance_interval;
6562 if (idle != CPU_IDLE)
6563 interval *= sd->busy_factor;
6565 /* scale ms to jiffies */
6566 interval = msecs_to_jiffies(interval);
6567 interval = clamp(interval, 1UL, max_load_balance_interval);
6569 need_serialize = sd->flags & SD_SERIALIZE;
6571 if (need_serialize) {
6572 if (!spin_trylock(&balancing))
6576 if (time_after_eq(jiffies, sd->last_balance + interval)) {
6577 if (load_balance(cpu, rq, sd, idle, &balance)) {
6579 * The LBF_SOME_PINNED logic could have changed
6580 * env->dst_cpu, so we can't know our idle
6581 * state even if we migrated tasks. Update it.
6583 idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE;
6585 sd->last_balance = jiffies;
6588 spin_unlock(&balancing);
6590 if (time_after(next_balance, sd->last_balance + interval)) {
6591 next_balance = sd->last_balance + interval;
6592 update_next_balance = 1;
6596 * Stop the load balance at this level. There is another
6597 * CPU in our sched group which is doing load balancing more
6606 * next_balance will be updated only when there is a need.
6607 * When the cpu is attached to null domain for ex, it will not be
6610 if (likely(update_next_balance))
6611 rq->next_balance = next_balance;
6614 #ifdef CONFIG_NO_HZ_COMMON
6616 * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
6617 * rebalancing for all the cpus for whom scheduler ticks are stopped.
6619 static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle)
6621 struct rq *this_rq = cpu_rq(this_cpu);
6625 if (idle != CPU_IDLE ||
6626 !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
6629 for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
6630 if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
6634 * If this cpu gets work to do, stop the load balancing
6635 * work being done for other cpus. Next load
6636 * balancing owner will pick it up.
6641 rq = cpu_rq(balance_cpu);
6643 raw_spin_lock_irq(&rq->lock);
6644 update_rq_clock(rq);
6645 update_idle_cpu_load(rq);
6646 raw_spin_unlock_irq(&rq->lock);
6648 rebalance_domains(balance_cpu, CPU_IDLE);
6650 if (time_after(this_rq->next_balance, rq->next_balance))
6651 this_rq->next_balance = rq->next_balance;
6653 nohz.next_balance = this_rq->next_balance;
6655 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu));
6659 * Current heuristic for kicking the idle load balancer in the presence
6660 * of an idle cpu is the system.
6661 * - This rq has more than one task.
6662 * - At any scheduler domain level, this cpu's scheduler group has multiple
6663 * busy cpu's exceeding the group's power.
6664 * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
6665 * domain span are idle.
6667 static inline int nohz_kick_needed(struct rq *rq, int cpu)
6669 unsigned long now = jiffies;
6670 struct sched_domain *sd;
6672 if (unlikely(idle_cpu(cpu)))
6676 * We may be recently in ticked or tickless idle mode. At the first
6677 * busy tick after returning from idle, we will update the busy stats.
6679 set_cpu_sd_state_busy();
6680 nohz_balance_exit_idle(cpu);
6683 * None are in tickless mode and hence no need for NOHZ idle load
6686 if (likely(!atomic_read(&nohz.nr_cpus)))
6689 if (time_before(now, nohz.next_balance))
6692 #ifdef CONFIG_SCHED_HMP
6694 * Bail out if there are no nohz CPUs in our
6695 * HMP domain, since we will move tasks between
6696 * domains through wakeup and force balancing
6697 * as necessary based upon task load.
6699 if (cpumask_first_and(nohz.idle_cpus_mask,
6700 &((struct hmp_domain *)hmp_cpu_domain(cpu))->cpus) >= nr_cpu_ids)
6704 if (rq->nr_running >= 2)
6708 for_each_domain(cpu, sd) {
6709 struct sched_group *sg = sd->groups;
6710 struct sched_group_power *sgp = sg->sgp;
6711 int nr_busy = atomic_read(&sgp->nr_busy_cpus);
6713 if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
6714 goto need_kick_unlock;
6716 if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
6717 && (cpumask_first_and(nohz.idle_cpus_mask,
6718 sched_domain_span(sd)) < cpu))
6719 goto need_kick_unlock;
6721 if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
6733 static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { }
6736 #ifdef CONFIG_SCHED_HMP
6737 /* Check if task should migrate to a faster cpu */
6738 static unsigned int hmp_up_migration(int cpu, int *target_cpu, struct sched_entity *se)
6740 struct task_struct *p = task_of(se);
6741 int temp_target_cpu;
6744 if (hmp_cpu_is_fastest(cpu))
6747 #ifdef CONFIG_SCHED_HMP_PRIO_FILTER
6748 /* Filter by task priority */
6749 if (p->prio >= hmp_up_prio)
6752 if (se->avg.load_avg_ratio < hmp_up_threshold)
6755 /* Let the task load settle before doing another up migration */
6756 /* hack - always use clock from first online CPU */
6757 now = cpu_rq(cpumask_first(cpu_online_mask))->clock_task;
6758 if (((now - se->avg.hmp_last_up_migration) >> 10)
6759 < hmp_next_up_threshold)
6762 /* hmp_domain_min_load only returns 0 for an
6763 * idle CPU or 1023 for any partly-busy one.
6764 * Be explicit about requirement for an idle CPU.
6766 if (hmp_domain_min_load(hmp_faster_domain(cpu), &temp_target_cpu,
6767 tsk_cpus_allowed(p)) == 0 && temp_target_cpu != NR_CPUS) {
6769 *target_cpu = temp_target_cpu;
6775 /* Check if task should migrate to a slower cpu */
6776 static unsigned int hmp_down_migration(int cpu, struct sched_entity *se)
6778 struct task_struct *p = task_of(se);
6781 if (hmp_cpu_is_slowest(cpu)) {
6782 #ifdef CONFIG_SCHED_HMP_LITTLE_PACKING
6783 if(hmp_packing_enabled)
6790 #ifdef CONFIG_SCHED_HMP_PRIO_FILTER
6791 /* Filter by task priority */
6792 if ((p->prio >= hmp_up_prio) &&
6793 cpumask_intersects(&hmp_slower_domain(cpu)->cpus,
6794 tsk_cpus_allowed(p))) {
6799 /* Let the task load settle before doing another down migration */
6800 /* hack - always use clock from first online CPU */
6801 now = cpu_rq(cpumask_first(cpu_online_mask))->clock_task;
6802 if (((now - se->avg.hmp_last_down_migration) >> 10)
6803 < hmp_next_down_threshold)
6806 if (cpumask_intersects(&hmp_slower_domain(cpu)->cpus,
6807 tsk_cpus_allowed(p))
6808 && se->avg.load_avg_ratio < hmp_down_threshold) {
6815 * hmp_can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
6816 * Ideally this function should be merged with can_migrate_task() to avoid
6819 static int hmp_can_migrate_task(struct task_struct *p, struct lb_env *env)
6821 int tsk_cache_hot = 0;
6824 * We do not migrate tasks that are:
6825 * 1) running (obviously), or
6826 * 2) cannot be migrated to this CPU due to cpus_allowed
6828 if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
6829 schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
6832 env->flags &= ~LBF_ALL_PINNED;
6834 if (task_running(env->src_rq, p)) {
6835 schedstat_inc(p, se.statistics.nr_failed_migrations_running);
6840 * Aggressive migration if:
6841 * 1) task is cache cold, or
6842 * 2) too many balance attempts have failed.
6845 tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
6846 if (!tsk_cache_hot ||
6847 env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
6848 #ifdef CONFIG_SCHEDSTATS
6849 if (tsk_cache_hot) {
6850 schedstat_inc(env->sd, lb_hot_gained[env->idle]);
6851 schedstat_inc(p, se.statistics.nr_forced_migrations);
6861 * move_specific_task tries to move a specific task.
6862 * Returns 1 if successful and 0 otherwise.
6863 * Called with both runqueues locked.
6865 static int move_specific_task(struct lb_env *env, struct task_struct *pm)
6867 struct task_struct *p, *n;
6869 list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
6870 if (throttled_lb_pair(task_group(p), env->src_rq->cpu,
6874 if (!hmp_can_migrate_task(p, env))
6876 /* Check if we found the right task */
6882 * Right now, this is only the third place move_task()
6883 * is called, so we can safely collect move_task()
6884 * stats here rather than inside move_task().
6886 schedstat_inc(env->sd, lb_gained[env->idle]);
6893 * hmp_active_task_migration_cpu_stop is run by cpu stopper and used to
6894 * migrate a specific task from one runqueue to another.
6895 * hmp_force_up_migration uses this to push a currently running task
6897 * Based on active_load_balance_stop_cpu and can potentially be merged.
6899 static int hmp_active_task_migration_cpu_stop(void *data)
6901 struct rq *busiest_rq = data;
6902 struct task_struct *p = busiest_rq->migrate_task;
6903 int busiest_cpu = cpu_of(busiest_rq);
6904 int target_cpu = busiest_rq->push_cpu;
6905 struct rq *target_rq = cpu_rq(target_cpu);
6906 struct sched_domain *sd;
6908 raw_spin_lock_irq(&busiest_rq->lock);
6909 /* make sure the requested cpu hasn't gone down in the meantime */
6910 if (unlikely(busiest_cpu != smp_processor_id() ||
6911 !busiest_rq->active_balance)) {
6914 /* Is there any task to move? */
6915 if (busiest_rq->nr_running <= 1)
6917 /* Task has migrated meanwhile, abort forced migration */
6918 if (task_rq(p) != busiest_rq)
6921 * This condition is "impossible", if it occurs
6922 * we need to fix it. Originally reported by
6923 * Bjorn Helgaas on a 128-cpu setup.
6925 BUG_ON(busiest_rq == target_rq);
6927 /* move a task from busiest_rq to target_rq */
6928 double_lock_balance(busiest_rq, target_rq);
6930 /* Search for an sd spanning us and the target CPU. */
6932 for_each_domain(target_cpu, sd) {
6933 if (cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
6938 struct lb_env env = {
6940 .dst_cpu = target_cpu,
6941 .dst_rq = target_rq,
6942 .src_cpu = busiest_rq->cpu,
6943 .src_rq = busiest_rq,
6947 schedstat_inc(sd, alb_count);
6949 if (move_specific_task(&env, p))
6950 schedstat_inc(sd, alb_pushed);
6952 schedstat_inc(sd, alb_failed);
6955 double_unlock_balance(busiest_rq, target_rq);
6958 busiest_rq->active_balance = 0;
6959 raw_spin_unlock_irq(&busiest_rq->lock);
6964 * hmp_idle_pull_cpu_stop is run by cpu stopper and used to
6965 * migrate a specific task from one runqueue to another.
6966 * hmp_idle_pull uses this to push a currently running task
6967 * off a runqueue to a faster CPU.
6968 * Locking is slightly different than usual.
6969 * Based on active_load_balance_stop_cpu and can potentially be merged.
6971 static int hmp_idle_pull_cpu_stop(void *data)
6973 struct rq *busiest_rq = data;
6974 struct task_struct *p = busiest_rq->migrate_task;
6975 int busiest_cpu = cpu_of(busiest_rq);
6976 int target_cpu = busiest_rq->push_cpu;
6977 struct rq *target_rq = cpu_rq(target_cpu);
6978 struct sched_domain *sd;
6980 raw_spin_lock_irq(&busiest_rq->lock);
6982 /* make sure the requested cpu hasn't gone down in the meantime */
6983 if (unlikely(busiest_cpu != smp_processor_id() ||
6984 !busiest_rq->active_balance))
6987 /* Is there any task to move? */
6988 if (busiest_rq->nr_running <= 1)
6991 /* Task has migrated meanwhile, abort forced migration */
6992 if (task_rq(p) != busiest_rq)
6996 * This condition is "impossible", if it occurs
6997 * we need to fix it. Originally reported by
6998 * Bjorn Helgaas on a 128-cpu setup.
7000 BUG_ON(busiest_rq == target_rq);
7002 /* move a task from busiest_rq to target_rq */
7003 double_lock_balance(busiest_rq, target_rq);
7005 /* Search for an sd spanning us and the target CPU. */
7007 for_each_domain(target_cpu, sd) {
7008 if (cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
7012 struct lb_env env = {
7014 .dst_cpu = target_cpu,
7015 .dst_rq = target_rq,
7016 .src_cpu = busiest_rq->cpu,
7017 .src_rq = busiest_rq,
7021 schedstat_inc(sd, alb_count);
7023 if (move_specific_task(&env, p))
7024 schedstat_inc(sd, alb_pushed);
7026 schedstat_inc(sd, alb_failed);
7029 double_unlock_balance(busiest_rq, target_rq);
7032 busiest_rq->active_balance = 0;
7033 raw_spin_unlock_irq(&busiest_rq->lock);
7038 * Move task in a runnable state to another CPU.
7040 * Tailored on 'active_load_balance_stop_cpu' with slight
7041 * modification to locking and pre-transfer checks. Note
7042 * rq->lock must be held before calling.
7044 static void hmp_migrate_runnable_task(struct rq *rq)
7046 struct sched_domain *sd;
7047 int src_cpu = cpu_of(rq);
7048 struct rq *src_rq = rq;
7049 int dst_cpu = rq->push_cpu;
7050 struct rq *dst_rq = cpu_rq(dst_cpu);
7051 struct task_struct *p = rq->migrate_task;
7053 * One last check to make sure nobody else is playing
7054 * with the source rq.
7056 if (src_rq->active_balance)
7059 if (src_rq->nr_running <= 1)
7062 if (task_rq(p) != src_rq)
7065 * Not sure if this applies here but one can never
7068 BUG_ON(src_rq == dst_rq);
7070 double_lock_balance(src_rq, dst_rq);
7073 for_each_domain(dst_cpu, sd) {
7074 if (cpumask_test_cpu(src_cpu, sched_domain_span(sd)))
7079 struct lb_env env = {
7088 schedstat_inc(sd, alb_count);
7090 if (move_specific_task(&env, p))
7091 schedstat_inc(sd, alb_pushed);
7093 schedstat_inc(sd, alb_failed);
7097 double_unlock_balance(src_rq, dst_rq);
7102 static DEFINE_SPINLOCK(hmp_force_migration);
7105 * hmp_force_up_migration checks runqueues for tasks that need to
7106 * be actively migrated to a faster cpu.
7108 static void hmp_force_up_migration(int this_cpu)
7110 int cpu, target_cpu;
7111 struct sched_entity *curr, *orig;
7113 unsigned long flags;
7114 unsigned int force, got_target;
7115 struct task_struct *p;
7117 if (!spin_trylock(&hmp_force_migration))
7119 for_each_online_cpu(cpu) {
7122 target = cpu_rq(cpu);
7123 raw_spin_lock_irqsave(&target->lock, flags);
7124 curr = target->cfs.curr;
7126 raw_spin_unlock_irqrestore(&target->lock, flags);
7129 if (!entity_is_task(curr)) {
7130 struct cfs_rq *cfs_rq;
7132 cfs_rq = group_cfs_rq(curr);
7134 curr = cfs_rq->curr;
7135 cfs_rq = group_cfs_rq(curr);
7139 curr = hmp_get_heaviest_task(curr, 1);
7141 if (hmp_up_migration(cpu, &target_cpu, curr)) {
7142 if (!target->active_balance) {
7144 target->push_cpu = target_cpu;
7145 target->migrate_task = p;
7147 trace_sched_hmp_migrate(p, target->push_cpu, HMP_MIGRATE_FORCE);
7148 hmp_next_up_delay(&p->se, target->push_cpu);
7151 if (!got_target && !target->active_balance) {
7153 * For now we just check the currently running task.
7154 * Selecting the lightest task for offloading will
7155 * require extensive book keeping.
7157 curr = hmp_get_lightest_task(orig, 1);
7159 target->push_cpu = hmp_offload_down(cpu, curr);
7160 if (target->push_cpu < NR_CPUS) {
7162 target->migrate_task = p;
7164 trace_sched_hmp_migrate(p, target->push_cpu, HMP_MIGRATE_OFFLOAD);
7165 hmp_next_down_delay(&p->se, target->push_cpu);
7169 * We have a target with no active_balance. If the task
7170 * is not currently running move it, otherwise let the
7171 * CPU stopper take care of it.
7173 if (got_target && !target->active_balance) {
7174 if (!task_running(target, p)) {
7175 trace_sched_hmp_migrate_force_running(p, 0);
7176 hmp_migrate_runnable_task(target);
7178 target->active_balance = 1;
7183 raw_spin_unlock_irqrestore(&target->lock, flags);
7186 stop_one_cpu_nowait(cpu_of(target),
7187 hmp_active_task_migration_cpu_stop,
7188 target, &target->active_balance_work);
7190 spin_unlock(&hmp_force_migration);
7193 * hmp_idle_pull looks at little domain runqueues to see
7194 * if a task should be pulled.
7196 * Reuses hmp_force_migration spinlock.
7199 static unsigned int hmp_idle_pull(int this_cpu)
7202 struct sched_entity *curr, *orig;
7203 struct hmp_domain *hmp_domain = NULL;
7204 struct rq *target = NULL, *rq;
7205 unsigned long flags, ratio = 0;
7206 unsigned int force = 0;
7207 struct task_struct *p = NULL;
7209 if (!hmp_cpu_is_slowest(this_cpu))
7210 hmp_domain = hmp_slower_domain(this_cpu);
7214 if (!spin_trylock(&hmp_force_migration))
7217 /* first select a task */
7218 for_each_cpu(cpu, &hmp_domain->cpus) {
7220 raw_spin_lock_irqsave(&rq->lock, flags);
7221 curr = rq->cfs.curr;
7223 raw_spin_unlock_irqrestore(&rq->lock, flags);
7226 if (!entity_is_task(curr)) {
7227 struct cfs_rq *cfs_rq;
7229 cfs_rq = group_cfs_rq(curr);
7231 curr = cfs_rq->curr;
7232 if (!entity_is_task(curr))
7233 cfs_rq = group_cfs_rq(curr);
7239 curr = hmp_get_heaviest_task(curr, 1);
7240 if (curr->avg.load_avg_ratio > hmp_up_threshold &&
7241 curr->avg.load_avg_ratio > ratio) {
7244 ratio = curr->avg.load_avg_ratio;
7246 raw_spin_unlock_irqrestore(&rq->lock, flags);
7252 /* now we have a candidate */
7253 raw_spin_lock_irqsave(&target->lock, flags);
7254 if (!target->active_balance && task_rq(p) == target) {
7256 target->push_cpu = this_cpu;
7257 target->migrate_task = p;
7258 trace_sched_hmp_migrate(p, target->push_cpu, HMP_MIGRATE_IDLE_PULL);
7259 hmp_next_up_delay(&p->se, target->push_cpu);
7261 * if the task isn't running move it right away.
7262 * Otherwise setup the active_balance mechanic and let
7263 * the CPU stopper do its job.
7265 if (!task_running(target, p)) {
7266 trace_sched_hmp_migrate_idle_running(p, 0);
7267 hmp_migrate_runnable_task(target);
7269 target->active_balance = 1;
7273 raw_spin_unlock_irqrestore(&target->lock, flags);
7276 stop_one_cpu_nowait(cpu_of(target),
7277 hmp_idle_pull_cpu_stop,
7278 target, &target->active_balance_work);
7281 spin_unlock(&hmp_force_migration);
7285 static void hmp_force_up_migration(int this_cpu) { }
7286 #endif /* CONFIG_SCHED_HMP */
7289 * run_rebalance_domains is triggered when needed from the scheduler tick.
7290 * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
7292 static void run_rebalance_domains(struct softirq_action *h)
7294 int this_cpu = smp_processor_id();
7295 struct rq *this_rq = cpu_rq(this_cpu);
7296 enum cpu_idle_type idle = this_rq->idle_balance ?
7297 CPU_IDLE : CPU_NOT_IDLE;
7299 hmp_force_up_migration(this_cpu);
7301 rebalance_domains(this_cpu, idle);
7304 * If this cpu has a pending nohz_balance_kick, then do the
7305 * balancing on behalf of the other idle cpus whose ticks are
7308 nohz_idle_balance(this_cpu, idle);
7311 static inline int on_null_domain(int cpu)
7313 return !rcu_dereference_sched(cpu_rq(cpu)->sd);
7317 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
7319 void trigger_load_balance(struct rq *rq, int cpu)
7321 /* Don't need to rebalance while attached to NULL domain */
7322 if (time_after_eq(jiffies, rq->next_balance) &&
7323 likely(!on_null_domain(cpu)))
7324 raise_softirq(SCHED_SOFTIRQ);
7325 #ifdef CONFIG_NO_HZ_COMMON
7326 if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu)))
7327 nohz_balancer_kick(cpu);
7331 static void rq_online_fair(struct rq *rq)
7333 #ifdef CONFIG_SCHED_HMP
7334 hmp_online_cpu(rq->cpu);
7339 static void rq_offline_fair(struct rq *rq)
7341 #ifdef CONFIG_SCHED_HMP
7342 hmp_offline_cpu(rq->cpu);
7346 /* Ensure any throttled groups are reachable by pick_next_task */
7347 unthrottle_offline_cfs_rqs(rq);
7350 #endif /* CONFIG_SMP */
7353 * scheduler tick hitting a task of our scheduling class:
7355 static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
7357 struct cfs_rq *cfs_rq;
7358 struct sched_entity *se = &curr->se;
7360 for_each_sched_entity(se) {
7361 cfs_rq = cfs_rq_of(se);
7362 entity_tick(cfs_rq, se, queued);
7365 if (sched_feat_numa(NUMA))
7366 task_tick_numa(rq, curr);
7368 update_rq_runnable_avg(rq, 1);
7372 * called on fork with the child task as argument from the parent's context
7373 * - child not yet on the tasklist
7374 * - preemption disabled
7376 static void task_fork_fair(struct task_struct *p)
7378 struct cfs_rq *cfs_rq;
7379 struct sched_entity *se = &p->se, *curr;
7380 int this_cpu = smp_processor_id();
7381 struct rq *rq = this_rq();
7382 unsigned long flags;
7384 raw_spin_lock_irqsave(&rq->lock, flags);
7386 update_rq_clock(rq);
7388 cfs_rq = task_cfs_rq(current);
7389 curr = cfs_rq->curr;
7392 * Not only the cpu but also the task_group of the parent might have
7393 * been changed after parent->se.parent,cfs_rq were copied to
7394 * child->se.parent,cfs_rq. So call __set_task_cpu() to make those
7395 * of child point to valid ones.
7398 __set_task_cpu(p, this_cpu);
7401 update_curr(cfs_rq);
7404 se->vruntime = curr->vruntime;
7405 place_entity(cfs_rq, se, 1);
7407 if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
7409 * Upon rescheduling, sched_class::put_prev_task() will place
7410 * 'current' within the tree based on its new key value.
7412 swap(curr->vruntime, se->vruntime);
7413 resched_task(rq->curr);
7416 se->vruntime -= cfs_rq->min_vruntime;
7418 raw_spin_unlock_irqrestore(&rq->lock, flags);
7422 * Priority of the task has changed. Check to see if we preempt
7426 prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
7432 * Reschedule if we are currently running on this runqueue and
7433 * our priority decreased, or if we are not currently running on
7434 * this runqueue and our priority is higher than the current's
7436 if (rq->curr == p) {
7437 if (p->prio > oldprio)
7438 resched_task(rq->curr);
7440 check_preempt_curr(rq, p, 0);
7443 static void switched_from_fair(struct rq *rq, struct task_struct *p)
7445 struct sched_entity *se = &p->se;
7446 struct cfs_rq *cfs_rq = cfs_rq_of(se);
7449 * Ensure the task's vruntime is normalized, so that when it's
7450 * switched back to the fair class the enqueue_entity(.flags=0) will
7451 * do the right thing.
7453 * If it's on_rq, then the dequeue_entity(.flags=0) will already
7454 * have normalized the vruntime, if it's !on_rq, then only when
7455 * the task is sleeping will it still have non-normalized vruntime.
7457 if (!p->on_rq && p->state != TASK_RUNNING) {
7459 * Fix up our vruntime so that the current sleep doesn't
7460 * cause 'unlimited' sleep bonus.
7462 place_entity(cfs_rq, se, 0);
7463 se->vruntime -= cfs_rq->min_vruntime;
7466 #if defined(CONFIG_FAIR_GROUP_SCHED) && defined(CONFIG_SMP)
7468 * Remove our load from contribution when we leave sched_fair
7469 * and ensure we don't carry in an old decay_count if we
7472 if (p->se.avg.decay_count) {
7473 struct cfs_rq *cfs_rq = cfs_rq_of(&p->se);
7474 __synchronize_entity_decay(&p->se);
7475 subtract_blocked_load_contrib(cfs_rq,
7476 p->se.avg.load_avg_contrib);
7482 * We switched to the sched_fair class.
7484 static void switched_to_fair(struct rq *rq, struct task_struct *p)
7490 * We were most likely switched from sched_rt, so
7491 * kick off the schedule if running, otherwise just see
7492 * if we can still preempt the current task.
7495 resched_task(rq->curr);
7497 check_preempt_curr(rq, p, 0);
7500 /* Account for a task changing its policy or group.
7502 * This routine is mostly called to set cfs_rq->curr field when a task
7503 * migrates between groups/classes.
7505 static void set_curr_task_fair(struct rq *rq)
7507 struct sched_entity *se = &rq->curr->se;
7509 for_each_sched_entity(se) {
7510 struct cfs_rq *cfs_rq = cfs_rq_of(se);
7512 set_next_entity(cfs_rq, se);
7513 /* ensure bandwidth has been allocated on our new cfs_rq */
7514 account_cfs_rq_runtime(cfs_rq, 0);
7518 void init_cfs_rq(struct cfs_rq *cfs_rq)
7520 cfs_rq->tasks_timeline = RB_ROOT;
7521 cfs_rq->min_vruntime = (u64)(-(1LL << 20));
7522 #ifndef CONFIG_64BIT
7523 cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
7525 #if defined(CONFIG_FAIR_GROUP_SCHED) && defined(CONFIG_SMP)
7526 atomic64_set(&cfs_rq->decay_counter, 1);
7527 atomic64_set(&cfs_rq->removed_load, 0);
7531 #ifdef CONFIG_FAIR_GROUP_SCHED
7532 static void task_move_group_fair(struct task_struct *p, int on_rq)
7534 struct cfs_rq *cfs_rq;
7536 * If the task was not on the rq at the time of this cgroup movement
7537 * it must have been asleep, sleeping tasks keep their ->vruntime
7538 * absolute on their old rq until wakeup (needed for the fair sleeper
7539 * bonus in place_entity()).
7541 * If it was on the rq, we've just 'preempted' it, which does convert
7542 * ->vruntime to a relative base.
7544 * Make sure both cases convert their relative position when migrating
7545 * to another cgroup's rq. This does somewhat interfere with the
7546 * fair sleeper stuff for the first placement, but who cares.
7549 * When !on_rq, vruntime of the task has usually NOT been normalized.
7550 * But there are some cases where it has already been normalized:
7552 * - Moving a forked child which is waiting for being woken up by
7553 * wake_up_new_task().
7554 * - Moving a task which has been woken up by try_to_wake_up() and
7555 * waiting for actually being woken up by sched_ttwu_pending().
7557 * To prevent boost or penalty in the new cfs_rq caused by delta
7558 * min_vruntime between the two cfs_rqs, we skip vruntime adjustment.
7560 if (!on_rq && (!p->se.sum_exec_runtime || p->state == TASK_WAKING))
7564 p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime;
7565 set_task_rq(p, task_cpu(p));
7567 cfs_rq = cfs_rq_of(&p->se);
7568 p->se.vruntime += cfs_rq->min_vruntime;
7571 * migrate_task_rq_fair() will have removed our previous
7572 * contribution, but we must synchronize for ongoing future
7575 p->se.avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
7576 cfs_rq->blocked_load_avg += p->se.avg.load_avg_contrib;
7581 void free_fair_sched_group(struct task_group *tg)
7585 destroy_cfs_bandwidth(tg_cfs_bandwidth(tg));
7587 for_each_possible_cpu(i) {
7589 kfree(tg->cfs_rq[i]);
7598 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
7600 struct cfs_rq *cfs_rq;
7601 struct sched_entity *se;
7604 tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL);
7607 tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL);
7611 tg->shares = NICE_0_LOAD;
7613 init_cfs_bandwidth(tg_cfs_bandwidth(tg));
7615 for_each_possible_cpu(i) {
7616 cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
7617 GFP_KERNEL, cpu_to_node(i));
7621 se = kzalloc_node(sizeof(struct sched_entity),
7622 GFP_KERNEL, cpu_to_node(i));
7626 init_cfs_rq(cfs_rq);
7627 init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);
7638 void unregister_fair_sched_group(struct task_group *tg, int cpu)
7640 struct rq *rq = cpu_rq(cpu);
7641 unsigned long flags;
7644 * Only empty task groups can be destroyed; so we can speculatively
7645 * check on_list without danger of it being re-added.
7647 if (!tg->cfs_rq[cpu]->on_list)
7650 raw_spin_lock_irqsave(&rq->lock, flags);
7651 list_del_leaf_cfs_rq(tg->cfs_rq[cpu]);
7652 raw_spin_unlock_irqrestore(&rq->lock, flags);
7655 void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
7656 struct sched_entity *se, int cpu,
7657 struct sched_entity *parent)
7659 struct rq *rq = cpu_rq(cpu);
7663 init_cfs_rq_runtime(cfs_rq);
7665 tg->cfs_rq[cpu] = cfs_rq;
7668 /* se could be NULL for root_task_group */
7673 se->cfs_rq = &rq->cfs;
7675 se->cfs_rq = parent->my_q;
7678 /* guarantee group entities always have weight */
7679 update_load_set(&se->load, NICE_0_LOAD);
7680 se->parent = parent;
7683 static DEFINE_MUTEX(shares_mutex);
7685 int sched_group_set_shares(struct task_group *tg, unsigned long shares)
7688 unsigned long flags;
7691 * We can't change the weight of the root cgroup.
7696 shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES));
7698 mutex_lock(&shares_mutex);
7699 if (tg->shares == shares)
7702 tg->shares = shares;
7703 for_each_possible_cpu(i) {
7704 struct rq *rq = cpu_rq(i);
7705 struct sched_entity *se;
7708 /* Propagate contribution to hierarchy */
7709 raw_spin_lock_irqsave(&rq->lock, flags);
7710 for_each_sched_entity(se)
7711 update_cfs_shares(group_cfs_rq(se));
7712 raw_spin_unlock_irqrestore(&rq->lock, flags);
7716 mutex_unlock(&shares_mutex);
7719 #else /* CONFIG_FAIR_GROUP_SCHED */
7721 void free_fair_sched_group(struct task_group *tg) { }
7723 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
7728 void unregister_fair_sched_group(struct task_group *tg, int cpu) { }
7730 #endif /* CONFIG_FAIR_GROUP_SCHED */
7733 static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
7735 struct sched_entity *se = &task->se;
7736 unsigned int rr_interval = 0;
7739 * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
7742 if (rq->cfs.load.weight)
7743 rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se));
7749 * All the scheduling class methods:
7751 const struct sched_class fair_sched_class = {
7752 .next = &idle_sched_class,
7753 .enqueue_task = enqueue_task_fair,
7754 .dequeue_task = dequeue_task_fair,
7755 .yield_task = yield_task_fair,
7756 .yield_to_task = yield_to_task_fair,
7758 .check_preempt_curr = check_preempt_wakeup,
7760 .pick_next_task = pick_next_task_fair,
7761 .put_prev_task = put_prev_task_fair,
7764 .select_task_rq = select_task_rq_fair,
7765 #ifdef CONFIG_FAIR_GROUP_SCHED
7766 .migrate_task_rq = migrate_task_rq_fair,
7768 .rq_online = rq_online_fair,
7769 .rq_offline = rq_offline_fair,
7771 .task_waking = task_waking_fair,
7774 .set_curr_task = set_curr_task_fair,
7775 .task_tick = task_tick_fair,
7776 .task_fork = task_fork_fair,
7778 .prio_changed = prio_changed_fair,
7779 .switched_from = switched_from_fair,
7780 .switched_to = switched_to_fair,
7782 .get_rr_interval = get_rr_interval_fair,
7784 #ifdef CONFIG_FAIR_GROUP_SCHED
7785 .task_move_group = task_move_group_fair,
7789 #ifdef CONFIG_SCHED_DEBUG
7790 void print_cfs_stats(struct seq_file *m, int cpu)
7792 struct cfs_rq *cfs_rq;
7795 for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
7796 print_cfs_rq(m, cpu, cfs_rq);
7801 __init void init_sched_fair_class(void)
7804 open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
7806 #ifdef CONFIG_NO_HZ_COMMON
7807 nohz.next_balance = jiffies;
7808 zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
7809 cpu_notifier(sched_ilb_notifier, 0);
7812 #ifdef CONFIG_SCHED_HMP
7813 hmp_cpu_mask_setup();
7819 #ifdef CONFIG_HMP_FREQUENCY_INVARIANT_SCALE
7820 static u32 cpufreq_calc_scale(u32 min, u32 max, u32 curr)
7822 u32 result = curr / max;
7826 /* Called when the CPU Frequency is changed.
7827 * Once for each CPU.
7829 static int cpufreq_callback(struct notifier_block *nb,
7830 unsigned long val, void *data)
7832 struct cpufreq_freqs *freq = data;
7833 int cpu = freq->cpu;
7834 struct cpufreq_extents *extents;
7836 if (freq->flags & CPUFREQ_CONST_LOOPS)
7839 if (val != CPUFREQ_POSTCHANGE)
7842 /* if dynamic load scale is disabled, set the load scale to 1.0 */
7843 if (!hmp_data.freqinvar_load_scale_enabled) {
7844 freq_scale[cpu].curr_scale = 1024;
7848 extents = &freq_scale[cpu];
7849 if (extents->flags & SCHED_LOAD_FREQINVAR_SINGLEFREQ) {
7850 /* If our governor was recognised as a single-freq governor,
7853 extents->curr_scale = 1024;
7855 extents->curr_scale = cpufreq_calc_scale(extents->min,
7856 extents->max, freq->new);
7862 /* Called when the CPUFreq governor is changed.
7863 * Only called for the CPUs which are actually changed by the
7866 static int cpufreq_policy_callback(struct notifier_block *nb,
7867 unsigned long event, void *data)
7869 struct cpufreq_policy *policy = data;
7870 struct cpufreq_extents *extents;
7871 int cpu, singleFreq = 0;
7872 static const char performance_governor[] = "performance";
7873 static const char powersave_governor[] = "powersave";
7875 if (event == CPUFREQ_START)
7878 if (event != CPUFREQ_INCOMPATIBLE)
7881 /* CPUFreq governors do not accurately report the range of
7882 * CPU Frequencies they will choose from.
7883 * We recognise performance and powersave governors as
7884 * single-frequency only.
7886 if (!strncmp(policy->governor->name, performance_governor,
7887 strlen(performance_governor)) ||
7888 !strncmp(policy->governor->name, powersave_governor,
7889 strlen(powersave_governor)))
7892 /* Make sure that all CPUs impacted by this policy are
7893 * updated since we will only get a notification when the
7894 * user explicitly changes the policy on a CPU.
7896 for_each_cpu(cpu, policy->cpus) {
7897 extents = &freq_scale[cpu];
7898 extents->max = policy->max >> SCHED_FREQSCALE_SHIFT;
7899 extents->min = policy->min >> SCHED_FREQSCALE_SHIFT;
7900 if (!hmp_data.freqinvar_load_scale_enabled) {
7901 extents->curr_scale = 1024;
7902 } else if (singleFreq) {
7903 extents->flags |= SCHED_LOAD_FREQINVAR_SINGLEFREQ;
7904 extents->curr_scale = 1024;
7906 extents->flags &= ~SCHED_LOAD_FREQINVAR_SINGLEFREQ;
7907 extents->curr_scale = cpufreq_calc_scale(extents->min,
7908 extents->max, policy->cur);
7915 static struct notifier_block cpufreq_notifier = {
7916 .notifier_call = cpufreq_callback,
7918 static struct notifier_block cpufreq_policy_notifier = {
7919 .notifier_call = cpufreq_policy_callback,
7922 static int __init register_sched_cpufreq_notifier(void)
7926 /* init safe defaults since there are no policies at registration */
7927 for (ret = 0; ret < CONFIG_NR_CPUS; ret++) {
7929 freq_scale[ret].max = 1024;
7930 freq_scale[ret].min = 1024;
7931 freq_scale[ret].curr_scale = 1024;
7934 pr_info("sched: registering cpufreq notifiers for scale-invariant loads\n");
7935 ret = cpufreq_register_notifier(&cpufreq_policy_notifier,
7936 CPUFREQ_POLICY_NOTIFIER);
7939 ret = cpufreq_register_notifier(&cpufreq_notifier,
7940 CPUFREQ_TRANSITION_NOTIFIER);
7945 core_initcall(register_sched_cpufreq_notifier);
7946 #endif /* CONFIG_HMP_FREQUENCY_INVARIANT_SCALE */