diff options
Diffstat (limited to 'kernel/sched_fair.c')
| -rw-r--r-- | kernel/sched_fair.c | 5601 |
1 files changed, 0 insertions, 5601 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c deleted file mode 100644 index cd3b64219d9..00000000000 --- a/kernel/sched_fair.c +++ /dev/null @@ -1,5601 +0,0 @@ -/* - * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH) - * - * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> - * - * Interactivity improvements by Mike Galbraith - * (C) 2007 Mike Galbraith <efault@gmx.de> - * - * Various enhancements by Dmitry Adamushko. - * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com> - * - * Group scheduling enhancements by Srivatsa Vaddagiri - * Copyright IBM Corporation, 2007 - * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> - * - * Scaled math optimizations by Thomas Gleixner - * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de> - * - * Adaptive scheduling granularity, math enhancements by Peter Zijlstra - * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> - */ - -#include <linux/latencytop.h> -#include <linux/sched.h> -#include <linux/cpumask.h> -#include <linux/slab.h> -#include <linux/profile.h> -#include <linux/interrupt.h> - -#include <trace/events/sched.h> - -#include "sched.h" - -/* - * Targeted preemption latency for CPU-bound tasks: - * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds) - * - * NOTE: this latency value is not the same as the concept of - * 'timeslice length' - timeslices in CFS are of variable length - * and have no persistent notion like in traditional, time-slice - * based scheduling concepts. - * - * (to see the precise effective timeslice length of your workload, - * run vmstat and monitor the context-switches (cs) field) - */ -unsigned int sysctl_sched_latency = 6000000ULL; -unsigned int normalized_sysctl_sched_latency = 6000000ULL; - -/* - * The initial- and re-scaling of tunables is configurable - * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus)) - * - * Options are: - * SCHED_TUNABLESCALING_NONE - unscaled, always *1 - * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus) - * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus - */ -enum sched_tunable_scaling sysctl_sched_tunable_scaling - = SCHED_TUNABLESCALING_LOG; - -/* - * Minimal preemption granularity for CPU-bound tasks: - * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds) - */ -unsigned int sysctl_sched_min_granularity = 750000ULL; -unsigned int normalized_sysctl_sched_min_granularity = 750000ULL; - -/* - * is kept at sysctl_sched_latency / sysctl_sched_min_granularity - */ -static unsigned int sched_nr_latency = 8; - -/* - * After fork, child runs first. If set to 0 (default) then - * parent will (try to) run first. - */ -unsigned int sysctl_sched_child_runs_first __read_mostly; - -/* - * SCHED_OTHER wake-up granularity. - * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds) - * - * This option delays the preemption effects of decoupled workloads - * and reduces their over-scheduling. Synchronous workloads will still - * have immediate wakeup/sleep latencies. - */ -unsigned int sysctl_sched_wakeup_granularity = 1000000UL; -unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL; - -const_debug unsigned int sysctl_sched_migration_cost = 500000UL; - -/* - * The exponential sliding window over which load is averaged for shares - * distribution. - * (default: 10msec) - */ -unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL; - -#ifdef CONFIG_CFS_BANDWIDTH -/* - * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool - * each time a cfs_rq requests quota. - * - * Note: in the case that the slice exceeds the runtime remaining (either due - * to consumption or the quota being specified to be smaller than the slice) - * we will always only issue the remaining available time. - * - * default: 5 msec, units: microseconds - */ -unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL; -#endif - -/* - * Increase the granularity value when there are more CPUs, - * because with more CPUs the 'effective latency' as visible - * to users decreases. But the relationship is not linear, - * so pick a second-best guess by going with the log2 of the - * number of CPUs. - * - * This idea comes from the SD scheduler of Con Kolivas: - */ -static int get_update_sysctl_factor(void) -{ - unsigned int cpus = min_t(int, num_online_cpus(), 8); - unsigned int factor; - - switch (sysctl_sched_tunable_scaling) { - case SCHED_TUNABLESCALING_NONE: - factor = 1; - break; - case SCHED_TUNABLESCALING_LINEAR: - factor = cpus; - break; - case SCHED_TUNABLESCALING_LOG: - default: - factor = 1 + ilog2(cpus); - break; - } - - return factor; -} - -static void update_sysctl(void) -{ - unsigned int factor = get_update_sysctl_factor(); - -#define SET_SYSCTL(name) \ - (sysctl_##name = (factor) * normalized_sysctl_##name) - SET_SYSCTL(sched_min_granularity); - SET_SYSCTL(sched_latency); - SET_SYSCTL(sched_wakeup_granularity); -#undef SET_SYSCTL -} - -void sched_init_granularity(void) -{ - update_sysctl(); -} - -#if BITS_PER_LONG == 32 -# define WMULT_CONST (~0UL) -#else -# define WMULT_CONST (1UL << 32) -#endif - -#define WMULT_SHIFT 32 - -/* - * Shift right and round: - */ -#define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y)) - -/* - * delta *= weight / lw - */ -static unsigned long -calc_delta_mine(unsigned long delta_exec, unsigned long weight, - struct load_weight *lw) -{ - u64 tmp; - - /* - * weight can be less than 2^SCHED_LOAD_RESOLUTION for task group sched - * entities since MIN_SHARES = 2. Treat weight as 1 if less than - * 2^SCHED_LOAD_RESOLUTION. - */ - if (likely(weight > (1UL << SCHED_LOAD_RESOLUTION))) - tmp = (u64)delta_exec * scale_load_down(weight); - else - tmp = (u64)delta_exec; - - if (!lw->inv_weight) { - unsigned long w = scale_load_down(lw->weight); - - if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST)) - lw->inv_weight = 1; - else if (unlikely(!w)) - lw->inv_weight = WMULT_CONST; - else - lw->inv_weight = WMULT_CONST / w; - } - - /* - * Check whether we'd overflow the 64-bit multiplication: - */ - if (unlikely(tmp > WMULT_CONST)) - tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight, - WMULT_SHIFT/2); - else - tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT); - - return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX); -} - - -const struct sched_class fair_sched_class; - -/************************************************************** - * CFS operations on generic schedulable entities: - */ - -#ifdef CONFIG_FAIR_GROUP_SCHED - -/* cpu runqueue to which this cfs_rq is attached */ -static inline struct rq *rq_of(struct cfs_rq *cfs_rq) -{ - return cfs_rq->rq; -} - -/* An entity is a task if it doesn't "own" a runqueue */ -#define entity_is_task(se) (!se->my_q) - -static inline struct task_struct *task_of(struct sched_entity *se) -{ -#ifdef CONFIG_SCHED_DEBUG - WARN_ON_ONCE(!entity_is_task(se)); -#endif - return container_of(se, struct task_struct, se); -} - -/* Walk up scheduling entities hierarchy */ -#define for_each_sched_entity(se) \ - for (; se; se = se->parent) - -static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) -{ - return p->se.cfs_rq; -} - -/* runqueue on which this entity is (to be) queued */ -static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) -{ - return se->cfs_rq; -} - -/* runqueue "owned" by this group */ -static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) -{ - return grp->my_q; -} - -static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) -{ - if (!cfs_rq->on_list) { - /* - * Ensure we either appear before our parent (if already - * enqueued) or force our parent to appear after us when it is - * enqueued. The fact that we always enqueue bottom-up - * reduces this to two cases. - */ - if (cfs_rq->tg->parent && - cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) { - list_add_rcu(&cfs_rq->leaf_cfs_rq_list, - &rq_of(cfs_rq)->leaf_cfs_rq_list); - } else { - list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list, - &rq_of(cfs_rq)->leaf_cfs_rq_list); - } - - cfs_rq->on_list = 1; - } -} - -static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) -{ - if (cfs_rq->on_list) { - list_del_rcu(&cfs_rq->leaf_cfs_rq_list); - cfs_rq->on_list = 0; - } -} - -/* Iterate thr' all leaf cfs_rq's on a runqueue */ -#define for_each_leaf_cfs_rq(rq, cfs_rq) \ - list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) - -/* Do the two (enqueued) entities belong to the same group ? */ -static inline int -is_same_group(struct sched_entity *se, struct sched_entity *pse) -{ - if (se->cfs_rq == pse->cfs_rq) - return 1; - - return 0; -} - -static inline struct sched_entity *parent_entity(struct sched_entity *se) -{ - return se->parent; -} - -/* return depth at which a sched entity is present in the hierarchy */ -static inline int depth_se(struct sched_entity *se) -{ - int depth = 0; - - for_each_sched_entity(se) - depth++; - - return depth; -} - -static void -find_matching_se(struct sched_entity **se, struct sched_entity **pse) -{ - int se_depth, pse_depth; - - /* - * preemption test can be made between sibling entities who are in the - * same cfs_rq i.e who have a common parent. Walk up the hierarchy of - * both tasks until we find their ancestors who are siblings of common - * parent. - */ - - /* First walk up until both entities are at same depth */ - se_depth = depth_se(*se); - pse_depth = depth_se(*pse); - - while (se_depth > pse_depth) { - se_depth--; - *se = parent_entity(*se); - } - - while (pse_depth > se_depth) { - pse_depth--; - *pse = parent_entity(*pse); - } - - while (!is_same_group(*se, *pse)) { - *se = parent_entity(*se); - *pse = parent_entity(*pse); - } -} - -#else /* !CONFIG_FAIR_GROUP_SCHED */ - -static inline struct task_struct *task_of(struct sched_entity *se) -{ - return container_of(se, struct task_struct, se); -} - -static inline struct rq *rq_of(struct cfs_rq *cfs_rq) -{ - return container_of(cfs_rq, struct rq, cfs); -} - -#define entity_is_task(se) 1 - -#define for_each_sched_entity(se) \ - for (; se; se = NULL) - -static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) -{ - return &task_rq(p)->cfs; -} - -static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) -{ - struct task_struct *p = task_of(se); - struct rq *rq = task_rq(p); - - return &rq->cfs; -} - -/* runqueue "owned" by this group */ -static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) -{ - return NULL; -} - -static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) -{ -} - -static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) -{ -} - -#define for_each_leaf_cfs_rq(rq, cfs_rq) \ - for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) - -static inline int -is_same_group(struct sched_entity *se, struct sched_entity *pse) -{ - return 1; -} - -static inline struct sched_entity *parent_entity(struct sched_entity *se) -{ - return NULL; -} - -static inline void -find_matching_se(struct sched_entity **se, struct sched_entity **pse) -{ -} - -#endif /* CONFIG_FAIR_GROUP_SCHED */ - -static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, - unsigned long delta_exec); - -/************************************************************** - * Scheduling class tree data structure manipulation methods: - */ - -static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime) -{ - s64 delta = (s64)(vruntime - min_vruntime); - if (delta > 0) - min_vruntime = vruntime; - - return min_vruntime; -} - -static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime) -{ - s64 delta = (s64)(vruntime - min_vruntime); - if (delta < 0) - min_vruntime = vruntime; - - return min_vruntime; -} - -static inline int entity_before(struct sched_entity *a, - struct sched_entity *b) -{ - return (s64)(a->vruntime - b->vruntime) < 0; -} - -static void update_min_vruntime(struct cfs_rq *cfs_rq) -{ - u64 vruntime = cfs_rq->min_vruntime; - - if (cfs_rq->curr) - vruntime = cfs_rq->curr->vruntime; - - if (cfs_rq->rb_leftmost) { - struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost, - struct sched_entity, - run_node); - - if (!cfs_rq->curr) - vruntime = se->vruntime; - else - vruntime = min_vruntime(vruntime, se->vruntime); - } - - cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); -#ifndef CONFIG_64BIT - smp_wmb(); - cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; -#endif -} - -/* - * Enqueue an entity into the rb-tree: - */ -static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - struct rb_node **link = &cfs_rq->tasks_timeline.rb_node; - struct rb_node *parent = NULL; - struct sched_entity *entry; - int leftmost = 1; - - /* - * Find the right place in the rbtree: - */ - while (*link) { - parent = *link; - entry = rb_entry(parent, struct sched_entity, run_node); - /* - * We dont care about collisions. Nodes with - * the same key stay together. - */ - if (entity_before(se, entry)) { - link = &parent->rb_left; - } else { - link = &parent->rb_right; - leftmost = 0; - } - } - - /* - * Maintain a cache of leftmost tree entries (it is frequently - * used): - */ - if (leftmost) - cfs_rq->rb_leftmost = &se->run_node; - - rb_link_node(&se->run_node, parent, link); - rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline); -} - -static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - if (cfs_rq->rb_leftmost == &se->run_node) { - struct rb_node *next_node; - - next_node = rb_next(&se->run_node); - cfs_rq->rb_leftmost = next_node; - } - - rb_erase(&se->run_node, &cfs_rq->tasks_timeline); -} - -struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq) -{ - struct rb_node *left = cfs_rq->rb_leftmost; - - if (!left) - return NULL; - - return rb_entry(left, struct sched_entity, run_node); -} - -static struct sched_entity *__pick_next_entity(struct sched_entity *se) -{ - struct rb_node *next = rb_next(&se->run_node); - - if (!next) - return NULL; - - return rb_entry(next, struct sched_entity, run_node); -} - -#ifdef CONFIG_SCHED_DEBUG -struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) -{ - struct rb_node *last = rb_last(&cfs_rq->tasks_timeline); - - if (!last) - return NULL; - - return rb_entry(last, struct sched_entity, run_node); -} - -/************************************************************** - * Scheduling class statistics methods: - */ - -int sched_proc_update_handler(struct ctl_table *table, int write, - void __user *buffer, size_t *lenp, - loff_t *ppos) -{ - int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); - int factor = get_update_sysctl_factor(); - - if (ret || !write) - return ret; - - sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency, - sysctl_sched_min_granularity); - -#define WRT_SYSCTL(name) \ - (normalized_sysctl_##name = sysctl_##name / (factor)) - WRT_SYSCTL(sched_min_granularity); - WRT_SYSCTL(sched_latency); - WRT_SYSCTL(sched_wakeup_granularity); -#undef WRT_SYSCTL - - return 0; -} -#endif - -/* - * delta /= w - */ -static inline unsigned long -calc_delta_fair(unsigned long delta, struct sched_entity *se) -{ - if (unlikely(se->load.weight != NICE_0_LOAD)) - delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load); - - return delta; -} - -/* - * The idea is to set a period in which each task runs once. - * - * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch - * this period because otherwise the slices get too small. - * - * p = (nr <= nl) ? l : l*nr/nl - */ -static u64 __sched_period(unsigned long nr_running) -{ - u64 period = sysctl_sched_latency; - unsigned long nr_latency = sched_nr_latency; - - if (unlikely(nr_running > nr_latency)) { - period = sysctl_sched_min_granularity; - period *= nr_running; - } - - return period; -} - -/* - * We calculate the wall-time slice from the period by taking a part - * proportional to the weight. - * - * s = p*P[w/rw] - */ -static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq); - - for_each_sched_entity(se) { - struct load_weight *load; - struct load_weight lw; - - cfs_rq = cfs_rq_of(se); - load = &cfs_rq->load; - - if (unlikely(!se->on_rq)) { - lw = cfs_rq->load; - - update_load_add(&lw, se->load.weight); - load = &lw; - } - slice = calc_delta_mine(slice, se->load.weight, load); - } - return slice; -} - -/* - * We calculate the vruntime slice of a to be inserted task - * - * vs = s/w - */ -static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - return calc_delta_fair(sched_slice(cfs_rq, se), se); -} - -static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update); -static void update_cfs_shares(struct cfs_rq *cfs_rq); - -/* - * Update the current task's runtime statistics. Skip current tasks that - * are not in our scheduling class. - */ -static inline void -__update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr, - unsigned long delta_exec) -{ - unsigned long delta_exec_weighted; - - schedstat_set(curr->statistics.exec_max, - max((u64)delta_exec, curr->statistics.exec_max)); - - curr->sum_exec_runtime += delta_exec; - schedstat_add(cfs_rq, exec_clock, delta_exec); - delta_exec_weighted = calc_delta_fair(delta_exec, curr); - - curr->vruntime += delta_exec_weighted; - update_min_vruntime(cfs_rq); - -#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED - cfs_rq->load_unacc_exec_time += delta_exec; -#endif -} - -static void update_curr(struct cfs_rq *cfs_rq) -{ - struct sched_entity *curr = cfs_rq->curr; - u64 now = rq_of(cfs_rq)->clock_task; - unsigned long delta_exec; - - if (unlikely(!curr)) - return; - - /* - * Get the amount of time the current task was running - * since the last time we changed load (this cannot - * overflow on 32 bits): - */ - delta_exec = (unsigned long)(now - curr->exec_start); - if (!delta_exec) - return; - - __update_curr(cfs_rq, curr, delta_exec); - curr->exec_start = now; - - if (entity_is_task(curr)) { - struct task_struct *curtask = task_of(curr); - - trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); - cpuacct_charge(curtask, delta_exec); - account_group_exec_runtime(curtask, delta_exec); - } - - account_cfs_rq_runtime(cfs_rq, delta_exec); -} - -static inline void -update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock); -} - -/* - * Task is being enqueued - update stats: - */ -static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - /* - * Are we enqueueing a waiting task? (for current tasks - * a dequeue/enqueue event is a NOP) - */ - if (se != cfs_rq->curr) - update_stats_wait_start(cfs_rq, se); -} - -static void -update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max, - rq_of(cfs_rq)->clock - se->statistics.wait_start)); - schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1); - schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum + - rq_of(cfs_rq)->clock - se->statistics.wait_start); -#ifdef CONFIG_SCHEDSTATS - if (entity_is_task(se)) { - trace_sched_stat_wait(task_of(se), - rq_of(cfs_rq)->clock - se->statistics.wait_start); - } -#endif - schedstat_set(se->statistics.wait_start, 0); -} - -static inline void -update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - /* - * Mark the end of the wait period if dequeueing a - * waiting task: - */ - if (se != cfs_rq->curr) - update_stats_wait_end(cfs_rq, se); -} - -/* - * We are picking a new current task - update its stats: - */ -static inline void -update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - /* - * We are starting a new run period: - */ - se->exec_start = rq_of(cfs_rq)->clock_task; -} - -/************************************************** - * Scheduling class queueing methods: - */ - -#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED -static void -add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight) -{ - cfs_rq->task_weight += weight; -} -#else -static inline void -add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight) -{ -} -#endif - -static void -account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - update_load_add(&cfs_rq->load, se->load.weight); - if (!parent_entity(se)) - update_load_add(&rq_of(cfs_rq)->load, se->load.weight); - if (entity_is_task(se)) { - add_cfs_task_weight(cfs_rq, se->load.weight); - list_add(&se->group_node, &cfs_rq->tasks); - } - cfs_rq->nr_running++; -} - -static void -account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - update_load_sub(&cfs_rq->load, se->load.weight); - if (!parent_entity(se)) - update_load_sub(&rq_of(cfs_rq)->load, se->load.weight); - if (entity_is_task(se)) { - add_cfs_task_weight(cfs_rq, -se->load.weight); - list_del_init(&se->group_node); - } - cfs_rq->nr_running--; -} - -#ifdef CONFIG_FAIR_GROUP_SCHED -/* we need this in update_cfs_load and load-balance functions below */ -static inline int throttled_hierarchy(struct cfs_rq *cfs_rq); -# ifdef CONFIG_SMP -static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq, - int global_update) -{ - struct task_group *tg = cfs_rq->tg; - long load_avg; - - load_avg = div64_u64(cfs_rq->load_avg, cfs_rq->load_period+1); - load_avg -= cfs_rq->load_contribution; - - if (global_update || abs(load_avg) > cfs_rq->load_contribution / 8) { - atomic_add(load_avg, &tg->load_weight); - cfs_rq->load_contribution += load_avg; - } -} - -static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update) -{ - u64 period = sysctl_sched_shares_window; - u64 now, delta; - unsigned long load = cfs_rq->load.weight; - - if (cfs_rq->tg == &root_task_group || throttled_hierarchy(cfs_rq)) - return; - - now = rq_of(cfs_rq)->clock_task; - delta = now - cfs_rq->load_stamp; - - /* truncate load history at 4 idle periods */ - if (cfs_rq->load_stamp > cfs_rq->load_last && - now - cfs_rq->load_last > 4 * period) { - cfs_rq->load_period = 0; - cfs_rq->load_avg = 0; - delta = period - 1; - } - - cfs_rq->load_stamp = now; - cfs_rq->load_unacc_exec_time = 0; - cfs_rq->load_period += delta; - if (load) { - cfs_rq->load_last = now; - cfs_rq->load_avg += delta * load; - } - - /* consider updating load contribution on each fold or truncate */ - if (global_update || cfs_rq->load_period > period - || !cfs_rq->load_period) - update_cfs_rq_load_contribution(cfs_rq, global_update); - - while (cfs_rq->load_period > period) { - /* - * Inline assembly required to prevent the compiler - * optimising this loop into a divmod call. - * See __iter_div_u64_rem() for another example of this. - */ - asm("" : "+rm" (cfs_rq->load_period)); - cfs_rq->load_period /= 2; - cfs_rq->load_avg /= 2; - } - - if (!cfs_rq->curr && !cfs_rq->nr_running && !cfs_rq->load_avg) - list_del_leaf_cfs_rq(cfs_rq); -} - -static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq) -{ - long tg_weight; - - /* - * Use this CPU's actual weight instead of the last load_contribution - * to gain a more accurate current total weight. See - * update_cfs_rq_load_contribution(). - */ - tg_weight = atomic_read(&tg->load_weight); - tg_weight -= cfs_rq->load_contribution; - tg_weight += cfs_rq->load.weight; - - return tg_weight; -} - -static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) -{ - long tg_weight, load, shares; - - tg_weight = calc_tg_weight(tg, cfs_rq); - load = cfs_rq->load.weight; - - shares = (tg->shares * load); - if (tg_weight) - shares /= tg_weight; - - if (shares < MIN_SHARES) - shares = MIN_SHARES; - if (shares > tg->shares) - shares = tg->shares; - - return shares; -} - -static void update_entity_shares_tick(struct cfs_rq *cfs_rq) -{ - if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) { - update_cfs_load(cfs_rq, 0); - update_cfs_shares(cfs_rq); - } -} -# else /* CONFIG_SMP */ -static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update) -{ -} - -static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) -{ - return tg->shares; -} - -static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq) -{ -} -# endif /* CONFIG_SMP */ -static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, - unsigned long weight) -{ - if (se->on_rq) { - /* commit outstanding execution time */ - if (cfs_rq->curr == se) - update_curr(cfs_rq); - account_entity_dequeue(cfs_rq, se); - } - - update_load_set(&se->load, weight); - - if (se->on_rq) - account_entity_enqueue(cfs_rq, se); -} - -static void update_cfs_shares(struct cfs_rq *cfs_rq) -{ - struct task_group *tg; - struct sched_entity *se; - long shares; - - tg = cfs_rq->tg; - se = tg->se[cpu_of(rq_of(cfs_rq))]; - if (!se || throttled_hierarchy(cfs_rq)) - return; -#ifndef CONFIG_SMP - if (likely(se->load.weight == tg->shares)) - return; -#endif - shares = calc_cfs_shares(cfs_rq, tg); - - reweight_entity(cfs_rq_of(se), se, shares); -} -#else /* CONFIG_FAIR_GROUP_SCHED */ -static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update) -{ -} - -static inline void update_cfs_shares(struct cfs_rq *cfs_rq) -{ -} - -static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq) -{ -} -#endif /* CONFIG_FAIR_GROUP_SCHED */ - -static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ -#ifdef CONFIG_SCHEDSTATS - struct task_struct *tsk = NULL; - - if (entity_is_task(se)) - tsk = task_of(se); - - if (se->statistics.sleep_start) { - u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start; - - if ((s64)delta < 0) - delta = 0; - - if (unlikely(delta > se->statistics.sleep_max)) - se->statistics.sleep_max = delta; - - se->statistics.sleep_start = 0; - se->statistics.sum_sleep_runtime += delta; - - if (tsk) { - account_scheduler_latency(tsk, delta >> 10, 1); - trace_sched_stat_sleep(tsk, delta); - } - } - if (se->statistics.block_start) { - u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start; - - if ((s64)delta < 0) - delta = 0; - - if (unlikely(delta > se->statistics.block_max)) - se->statistics.block_max = delta; - - se->statistics.block_start = 0; - se->statistics.sum_sleep_runtime += delta; - - if (tsk) { - if (tsk->in_iowait) { - se->statistics.iowait_sum += delta; - se->statistics.iowait_count++; - trace_sched_stat_iowait(tsk, delta); - } - - /* - * Blocking time is in units of nanosecs, so shift by - * 20 to get a milliseconds-range estimation of the - * amount of time that the task spent sleeping: - */ - if (unlikely(prof_on == SLEEP_PROFILING)) { - profile_hits(SLEEP_PROFILING, - (void *)get_wchan(tsk), - delta >> 20); - } - account_scheduler_latency(tsk, delta >> 10, 0); - } - } -#endif -} - -static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ -#ifdef CONFIG_SCHED_DEBUG - s64 d = se->vruntime - cfs_rq->min_vruntime; - - if (d < 0) - d = -d; - - if (d > 3*sysctl_sched_latency) - schedstat_inc(cfs_rq, nr_spread_over); -#endif -} - -static void -place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) -{ - u64 vruntime = cfs_rq->min_vruntime; - - /* - * The 'current' period is already promised to the current tasks, - * however the extra weight of the new task will slow them down a - * little, place the new task so that it fits in the slot that - * stays open at the end. - */ - if (initial && sched_feat(START_DEBIT)) - vruntime += sched_vslice(cfs_rq, se); - - /* sleeps up to a single latency don't count. */ - if (!initial) { - unsigned long thresh = sysctl_sched_latency; - - /* - * Halve their sleep time's effect, to allow - * for a gentler effect of sleepers: - */ - if (sched_feat(GENTLE_FAIR_SLEEPERS)) - thresh >>= 1; - - vruntime -= thresh; - } - - /* ensure we never gain time by being placed backwards. */ - vruntime = max_vruntime(se->vruntime, vruntime); - - se->vruntime = vruntime; -} - -static void check_enqueue_throttle(struct cfs_rq *cfs_rq); - -static void -enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) -{ - /* - * Update the normalized vruntime before updating min_vruntime - * through callig update_curr(). - */ - if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING)) - se->vruntime += cfs_rq->min_vruntime; - - /* - * Update run-time statistics of the 'current'. - */ - update_curr(cfs_rq); - update_cfs_load(cfs_rq, 0); - account_entity_enqueue(cfs_rq, se); - update_cfs_shares(cfs_rq); - - if (flags & ENQUEUE_WAKEUP) { - place_entity(cfs_rq, se, 0); - enqueue_sleeper(cfs_rq, se); - } - - update_stats_enqueue(cfs_rq, se); - check_spread(cfs_rq, se); - if (se != cfs_rq->curr) - __enqueue_entity(cfs_rq, se); - se->on_rq = 1; - - if (cfs_rq->nr_running == 1) { - list_add_leaf_cfs_rq(cfs_rq); - check_enqueue_throttle(cfs_rq); - } -} - -static void __clear_buddies_last(struct sched_entity *se) -{ - for_each_sched_entity(se) { - struct cfs_rq *cfs_rq = cfs_rq_of(se); - if (cfs_rq->last == se) - cfs_rq->last = NULL; - else - break; - } -} - -static void __clear_buddies_next(struct sched_entity *se) -{ - for_each_sched_entity(se) { - struct cfs_rq *cfs_rq = cfs_rq_of(se); - if (cfs_rq->next == se) - cfs_rq->next = NULL; - else - break; - } -} - -static void __clear_buddies_skip(struct sched_entity *se) -{ - for_each_sched_entity(se) { - struct cfs_rq *cfs_rq = cfs_rq_of(se); - if (cfs_rq->skip == se) - cfs_rq->skip = NULL; - else - break; - } -} - -static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - if (cfs_rq->last == se) - __clear_buddies_last(se); - - if (cfs_rq->next == se) - __clear_buddies_next(se); - - if (cfs_rq->skip == se) - __clear_buddies_skip(se); -} - -static void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); - -static void -dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) -{ - /* - * Update run-time statistics of the 'current'. - */ - update_curr(cfs_rq); - - update_stats_dequeue(cfs_rq, se); - if (flags & DEQUEUE_SLEEP) { -#ifdef CONFIG_SCHEDSTATS - if (entity_is_task(se)) { - struct task_struct *tsk = task_of(se); - - if (tsk->state & TASK_INTERRUPTIBLE) - se->statistics.sleep_start = rq_of(cfs_rq)->clock; - if (tsk->state & TASK_UNINTERRUPTIBLE) - se->statistics.block_start = rq_of(cfs_rq)->clock; - } -#endif - } - - clear_buddies(cfs_rq, se); - - if (se != cfs_rq->curr) - __dequeue_entity(cfs_rq, se); - se->on_rq = 0; - update_cfs_load(cfs_rq, 0); - account_entity_dequeue(cfs_rq, se); - - /* - * Normalize the entity after updating the min_vruntime because the - * update can refer to the ->curr item and we need to reflect this - * movement in our normalized position. - */ - if (!(flags & DEQUEUE_SLEEP)) - se->vruntime -= cfs_rq->min_vruntime; - - /* return excess runtime on last dequeue */ - return_cfs_rq_runtime(cfs_rq); - - update_min_vruntime(cfs_rq); - update_cfs_shares(cfs_rq); -} - -/* - * Preempt the current task with a newly woken task if needed: - */ -static void -check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) -{ - unsigned long ideal_runtime, delta_exec; - struct sched_entity *se; - s64 delta; - - ideal_runtime = sched_slice(cfs_rq, curr); - delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; - if (delta_exec > ideal_runtime) { - resched_task(rq_of(cfs_rq)->curr); - /* - * The current task ran long enough, ensure it doesn't get - * re-elected due to buddy favours. - */ - clear_buddies(cfs_rq, curr); - return; - } - - /* - * Ensure that a task that missed wakeup preemption by a - * narrow margin doesn't have to wait for a full slice. - * This also mitigates buddy induced latencies under load. - */ - if (delta_exec < sysctl_sched_min_granularity) - return; - - se = __pick_first_entity(cfs_rq); - delta = curr->vruntime - se->vruntime; - - if (delta < 0) - return; - - if (delta > ideal_runtime) - resched_task(rq_of(cfs_rq)->curr); -} - -static void -set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) -{ - /* 'current' is not kept within the tree. */ - if (se->on_rq) { - /* - * Any task has to be enqueued before it get to execute on - * a CPU. So account for the time it spent waiting on the - * runqueue. - */ - update_stats_wait_end(cfs_rq, se); - __dequeue_entity(cfs_rq, se); - } - - update_stats_curr_start(cfs_rq, se); - cfs_rq->curr = se; -#ifdef CONFIG_SCHEDSTATS - /* - * Track our maximum slice length, if the CPU's load is at - * least twice that of our own weight (i.e. dont track it - * when there are only lesser-weight tasks around): - */ - if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) { - se->statistics.slice_max = max(se->statistics.slice_max, - se->sum_exec_runtime - se->prev_sum_exec_runtime); - } -#endif - se->prev_sum_exec_runtime = se->sum_exec_runtime; -} - -static int -wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se); - -/* - * Pick the next process, keeping these things in mind, in this order: - * 1) keep things fair between processes/task groups - * 2) pick the "next" process, since someone really wants that to run - * 3) pick the "last" process, for cache locality - * 4) do not run the "skip" process, if something else is available - */ -static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) -{ - struct sched_entity *se = __pick_first_entity(cfs_rq); - struct sched_entity *left = se; - - /* - * Avoid running the skip buddy, if running something else can - * be done without getting too unfair. - */ - if (cfs_rq->skip == se) { - struct sched_entity *second = __pick_next_entity(se); - if (second && wakeup_preempt_entity(second, left) < 1) - se = second; - } - - /* - * Prefer last buddy, try to return the CPU to a preempted task. - */ - if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) - se = cfs_rq->last; - - /* - * Someone really wants this to run. If it's not unfair, run it. - */ - if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) - se = cfs_rq->next; - - clear_buddies(cfs_rq, se); - - return se; -} - -static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq); - -static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) -{ - /* - * If still on the runqueue then deactivate_task() - * was not called and update_curr() has to be done: - */ - if (prev->on_rq) - update_curr(cfs_rq); - - /* throttle cfs_rqs exceeding runtime */ - check_cfs_rq_runtime(cfs_rq); - - check_spread(cfs_rq, prev); - if (prev->on_rq) { - update_stats_wait_start(cfs_rq, prev); - /* Put 'current' back into the tree. */ - __enqueue_entity(cfs_rq, prev); - } - cfs_rq->curr = NULL; -} - -static void -entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) -{ - /* - * Update run-time statistics of the 'current'. - */ - update_curr(cfs_rq); - - /* - * Update share accounting for long-running entities. - */ - update_entity_shares_tick(cfs_rq); - -#ifdef CONFIG_SCHED_HRTICK - /* - * queued ticks are scheduled to match the slice, so don't bother - * validating it and just reschedule. - */ - if (queued) { - resched_task(rq_of(cfs_rq)->curr); - return; - } - /* - * don't let the period tick interfere with the hrtick preemption - */ - if (!sched_feat(DOUBLE_TICK) && - hrtimer_active(&rq_of(cfs_rq)->hrtick_timer)) - return; -#endif - - if (cfs_rq->nr_running > 1) - check_preempt_tick(cfs_rq, curr); -} - - -/************************************************** - * CFS bandwidth control machinery - */ - -#ifdef CONFIG_CFS_BANDWIDTH - -#ifdef HAVE_JUMP_LABEL -static struct jump_label_key __cfs_bandwidth_used; - -static inline bool cfs_bandwidth_used(void) -{ - return static_branch(&__cfs_bandwidth_used); -} - -void account_cfs_bandwidth_used(int enabled, int was_enabled) -{ - /* only need to count groups transitioning between enabled/!enabled */ - if (enabled && !was_enabled) - jump_label_inc(&__cfs_bandwidth_used); - else if (!enabled && was_enabled) - jump_label_dec(&__cfs_bandwidth_used); -} -#else /* HAVE_JUMP_LABEL */ -static bool cfs_bandwidth_used(void) -{ - return true; -} - -void account_cfs_bandwidth_used(int enabled, int was_enabled) {} -#endif /* HAVE_JUMP_LABEL */ - -/* - * default period for cfs group bandwidth. - * default: 0.1s, units: nanoseconds - */ -static inline u64 default_cfs_period(void) -{ - return 100000000ULL; -} - -static inline u64 sched_cfs_bandwidth_slice(void) -{ - return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC; -} - -/* - * Replenish runtime according to assigned quota and update expiration time. - * We use sched_clock_cpu directly instead of rq->clock to avoid adding - * additional synchronization around rq->lock. - * - * requires cfs_b->lock - */ -void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b) -{ - u64 now; - - if (cfs_b->quota == RUNTIME_INF) - return; - - now = sched_clock_cpu(smp_processor_id()); - cfs_b->runtime = cfs_b->quota; - cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period); -} - -static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) -{ - return &tg->cfs_bandwidth; -} - -/* returns 0 on failure to allocate runtime */ -static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq) -{ - struct task_group *tg = cfs_rq->tg; - struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg); - u64 amount = 0, min_amount, expires; - - /* note: this is a positive sum as runtime_remaining <= 0 */ - min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining; - - raw_spin_lock(&cfs_b->lock); - if (cfs_b->quota == RUNTIME_INF) - amount = min_amount; - else { - /* - * If the bandwidth pool has become inactive, then at least one - * period must have elapsed since the last consumption. - * Refresh the global state and ensure bandwidth timer becomes - * active. - */ - if (!cfs_b->timer_active) { - __refill_cfs_bandwidth_runtime(cfs_b); - __start_cfs_bandwidth(cfs_b); - } - - if (cfs_b->runtime > 0) { - amount = min(cfs_b->runtime, min_amount); - cfs_b->runtime -= amount; - cfs_b->idle = 0; - } - } - expires = cfs_b->runtime_expires; - raw_spin_unlock(&cfs_b->lock); - - cfs_rq->runtime_remaining += amount; - /* - * we may have advanced our local expiration to account for allowed - * spread between our sched_clock and the one on which runtime was - * issued. - */ - if ((s64)(expires - cfs_rq->runtime_expires) > 0) - cfs_rq->runtime_expires = expires; - - return cfs_rq->runtime_remaining > 0; -} - -/* - * Note: This depends on the synchronization provided by sched_clock and the - * fact that rq->clock snapshots this value. - */ -static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq) -{ - struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); - struct rq *rq = rq_of(cfs_rq); - - /* if the deadline is ahead of our clock, nothing to do */ - if (likely((s64)(rq->clock - cfs_rq->runtime_expires) < 0)) - return; - - if (cfs_rq->runtime_remaining < 0) - return; - - /* - * If the local deadline has passed we have to consider the - * possibility that our sched_clock is 'fast' and the global deadline - * has not truly expired. - * - * Fortunately we can check determine whether this the case by checking - * whether the global deadline has advanced. - */ - - if ((s64)(cfs_rq->runtime_expires - cfs_b->runtime_expires) >= 0) { - /* extend local deadline, drift is bounded above by 2 ticks */ - cfs_rq->runtime_expires += TICK_NSEC; - } else { - /* global deadline is ahead, expiration has passed */ - cfs_rq->runtime_remaining = 0; - } -} - -static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, - unsigned long delta_exec) -{ - /* dock delta_exec before expiring quota (as it could span periods) */ - cfs_rq->runtime_remaining -= delta_exec; - expire_cfs_rq_runtime(cfs_rq); - - if (likely(cfs_rq->runtime_remaining > 0)) - return; - - /* - * if we're unable to extend our runtime we resched so that the active - * hierarchy can be throttled - */ - if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr)) - resched_task(rq_of(cfs_rq)->curr); -} - -static __always_inline void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, - unsigned long delta_exec) -{ - if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled) - return; - - __account_cfs_rq_runtime(cfs_rq, delta_exec); -} - -static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) -{ - return cfs_bandwidth_used() && cfs_rq->throttled; -} - -/* check whether cfs_rq, or any parent, is throttled */ -static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) -{ - return cfs_bandwidth_used() && cfs_rq->throttle_count; -} - -/* - * Ensure that neither of the group entities corresponding to src_cpu or - * dest_cpu are members of a throttled hierarchy when performing group - * load-balance operations. - */ -static inline int throttled_lb_pair(struct task_group *tg, - int src_cpu, int dest_cpu) -{ - struct cfs_rq *src_cfs_rq, *dest_cfs_rq; - - src_cfs_rq = tg->cfs_rq[src_cpu]; - dest_cfs_rq = tg->cfs_rq[dest_cpu]; - - return throttled_hierarchy(src_cfs_rq) || - throttled_hierarchy(dest_cfs_rq); -} - -/* updated child weight may affect parent so we have to do this bottom up */ -static int tg_unthrottle_up(struct task_group *tg, void *data) -{ - struct rq *rq = data; - struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; - - cfs_rq->throttle_count--; -#ifdef CONFIG_SMP - if (!cfs_rq->throttle_count) { - u64 delta = rq->clock_task - cfs_rq->load_stamp; - - /* leaving throttled state, advance shares averaging windows */ - cfs_rq->load_stamp += delta; - cfs_rq->load_last += delta; - - /* update entity weight now that we are on_rq again */ - update_cfs_shares(cfs_rq); - } -#endif - - return 0; -} - -static int tg_throttle_down(struct task_group *tg, void *data) -{ - struct rq *rq = data; - struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; - - /* group is entering throttled state, record last load */ - if (!cfs_rq->throttle_count) - update_cfs_load(cfs_rq, 0); - cfs_rq->throttle_count++; - - return 0; -} - -static void throttle_cfs_rq(struct cfs_rq *cfs_rq) -{ - struct rq *rq = rq_of(cfs_rq); - struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); - struct sched_entity *se; - long task_delta, dequeue = 1; - - se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; - - /* account load preceding throttle */ - rcu_read_lock(); - walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq); - rcu_read_unlock(); - - task_delta = cfs_rq->h_nr_running; - for_each_sched_entity(se) { - struct cfs_rq *qcfs_rq = cfs_rq_of(se); - /* throttled entity or throttle-on-deactivate */ - if (!se->on_rq) - break; - - if (dequeue) - dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP); - qcfs_rq->h_nr_running -= task_delta; - - if (qcfs_rq->load.weight) - dequeue = 0; - } - - if (!se) - rq->nr_running -= task_delta; - - cfs_rq->throttled = 1; - cfs_rq->throttled_timestamp = rq->clock; - raw_spin_lock(&cfs_b->lock); - list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq); - raw_spin_unlock(&cfs_b->lock); -} - -void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) -{ - struct rq *rq = rq_of(cfs_rq); - struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); - struct sched_entity *se; - int enqueue = 1; - long task_delta; - - se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; - - cfs_rq->throttled = 0; - raw_spin_lock(&cfs_b->lock); - cfs_b->throttled_time += rq->clock - cfs_rq->throttled_timestamp; - list_del_rcu(&cfs_rq->throttled_list); - raw_spin_unlock(&cfs_b->lock); - cfs_rq->throttled_timestamp = 0; - - update_rq_clock(rq); - /* update hierarchical throttle state */ - walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq); - - if (!cfs_rq->load.weight) - return; - - task_delta = cfs_rq->h_nr_running; - for_each_sched_entity(se) { - if (se->on_rq) - enqueue = 0; - - cfs_rq = cfs_rq_of(se); - if (enqueue) - enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP); - cfs_rq->h_nr_running += task_delta; - - if (cfs_rq_throttled(cfs_rq)) - break; - } - - if (!se) - rq->nr_running += task_delta; - - /* determine whether we need to wake up potentially idle cpu */ - if (rq->curr == rq->idle && rq->cfs.nr_running) - resched_task(rq->curr); -} - -static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, - u64 remaining, u64 expires) -{ - struct cfs_rq *cfs_rq; - u64 runtime = remaining; - - rcu_read_lock(); - list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq, - throttled_list) { - struct rq *rq = rq_of(cfs_rq); - - raw_spin_lock(&rq->lock); - if (!cfs_rq_throttled(cfs_rq)) - goto next; - - runtime = -cfs_rq->runtime_remaining + 1; - if (runtime > remaining) - runtime = remaining; - remaining -= runtime; - - cfs_rq->runtime_remaining += runtime; - cfs_rq->runtime_expires = expires; - - /* we check whether we're throttled above */ - if (cfs_rq->runtime_remaining > 0) - unthrottle_cfs_rq(cfs_rq); - -next: - raw_spin_unlock(&rq->lock); - - if (!remaining) - break; - } - rcu_read_unlock(); - - return remaining; -} - -/* - * Responsible for refilling a task_group's bandwidth and unthrottling its - * cfs_rqs as appropriate. If there has been no activity within the last - * period the timer is deactivated until scheduling resumes; cfs_b->idle is - * used to track this state. - */ -static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) -{ - u64 runtime, runtime_expires; - int idle = 1, throttled; - - raw_spin_lock(&cfs_b->lock); - /* no need to continue the timer with no bandwidth constraint */ - if (cfs_b->quota == RUNTIME_INF) - goto out_unlock; - - throttled = !list_empty(&cfs_b->throttled_cfs_rq); - /* idle depends on !throttled (for the case of a large deficit) */ - idle = cfs_b->idle && !throttled; - cfs_b->nr_periods += overrun; - - /* if we're going inactive then everything else can be deferred */ - if (idle) - goto out_unlock; - - __refill_cfs_bandwidth_runtime(cfs_b); - - if (!throttled) { - /* mark as potentially idle for the upcoming period */ - cfs_b->idle = 1; - goto out_unlock; - } - - /* account preceding periods in which throttling occurred */ - cfs_b->nr_throttled += overrun; - - /* - * There are throttled entities so we must first use the new bandwidth - * to unthrottle them before making it generally available. This - * ensures that all existing debts will be paid before a new cfs_rq is - * allowed to run. - */ - runtime = cfs_b->runtime; - runtime_expires = cfs_b->runtime_expires; - cfs_b->runtime = 0; - - /* - * This check is repeated as we are holding onto the new bandwidth - * while we unthrottle. This can potentially race with an unthrottled - * group trying to acquire new bandwidth from the global pool. - */ - while (throttled && runtime > 0) { - raw_spin_unlock(&cfs_b->lock); - /* we can't nest cfs_b->lock while distributing bandwidth */ - runtime = distribute_cfs_runtime(cfs_b, runtime, - runtime_expires); - raw_spin_lock(&cfs_b->lock); - - throttled = !list_empty(&cfs_b->throttled_cfs_rq); - } - - /* return (any) remaining runtime */ - cfs_b->runtime = runtime; - /* - * While we are ensured activity in the period following an - * unthrottle, this also covers the case in which the new bandwidth is - * insufficient to cover the existing bandwidth deficit. (Forcing the - * timer to remain active while there are any throttled entities.) - */ - cfs_b->idle = 0; -out_unlock: - if (idle) - cfs_b->timer_active = 0; - raw_spin_unlock(&cfs_b->lock); - - return idle; -} - -/* a cfs_rq won't donate quota below this amount */ -static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC; -/* minimum remaining period time to redistribute slack quota */ -static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC; -/* how long we wait to gather additional slack before distributing */ -static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC; - -/* are we near the end of the current quota period? */ -static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) -{ - struct hrtimer *refresh_timer = &cfs_b->period_timer; - u64 remaining; - - /* if the call-back is running a quota refresh is already occurring */ - if (hrtimer_callback_running(refresh_timer)) - return 1; - - /* is a quota refresh about to occur? */ - remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer)); - if (remaining < min_expire) - return 1; - - return 0; -} - -static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b) -{ - u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration; - - /* if there's a quota refresh soon don't bother with slack */ - if (runtime_refresh_within(cfs_b, min_left)) - return; - - start_bandwidth_timer(&cfs_b->slack_timer, - ns_to_ktime(cfs_bandwidth_slack_period)); -} - -/* we know any runtime found here is valid as update_curr() precedes return */ -static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq) -{ - struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); - s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime; - - if (slack_runtime <= 0) - return; - - raw_spin_lock(&cfs_b->lock); - if (cfs_b->quota != RUNTIME_INF && - cfs_rq->runtime_expires == cfs_b->runtime_expires) { - cfs_b->runtime += slack_runtime; - - /* we are under rq->lock, defer unthrottling using a timer */ - if (cfs_b->runtime > sched_cfs_bandwidth_slice() && - !list_empty(&cfs_b->throttled_cfs_rq)) - start_cfs_slack_bandwidth(cfs_b); - } - raw_spin_unlock(&cfs_b->lock); - - /* even if it's not valid for return we don't want to try again */ - cfs_rq->runtime_remaining -= slack_runtime; -} - -static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) -{ - if (!cfs_bandwidth_used()) - return; - - if (!cfs_rq->runtime_enabled || cfs_rq->nr_running) - return; - - __return_cfs_rq_runtime(cfs_rq); -} - -/* - * This is done with a timer (instead of inline with bandwidth return) since - * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs. - */ -static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b) -{ - u64 runtime = 0, slice = sched_cfs_bandwidth_slice(); - u64 expires; - - /* confirm we're still not at a refresh boundary */ - if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) - return; - - raw_spin_lock(&cfs_b->lock); - if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) { - runtime = cfs_b->runtime; - cfs_b->runtime = 0; - } - expires = cfs_b->runtime_expires; - raw_spin_unlock(&cfs_b->lock); - - if (!runtime) - return; - - runtime = distribute_cfs_runtime(cfs_b, runtime, expires); - - raw_spin_lock(&cfs_b->lock); - if (expires == cfs_b->runtime_expires) - cfs_b->runtime = runtime; - raw_spin_unlock(&cfs_b->lock); -} - -/* - * When a group wakes up we want to make sure that its quota is not already - * expired/exceeded, otherwise it may be allowed to steal additional ticks of - * runtime as update_curr() throttling can not not trigger until it's on-rq. - */ -static void check_enqueue_throttle(struct cfs_rq *cfs_rq) -{ - if (!cfs_bandwidth_used()) - return; - - /* an active group must be handled by the update_curr()->put() path */ - if (!cfs_rq->runtime_enabled || cfs_rq->curr) - return; - - /* ensure the group is not already throttled */ - if (cfs_rq_throttled(cfs_rq)) - return; - - /* update runtime allocation */ - account_cfs_rq_runtime(cfs_rq, 0); - if (cfs_rq->runtime_remaining <= 0) - throttle_cfs_rq(cfs_rq); -} - -/* conditionally throttle active cfs_rq's from put_prev_entity() */ -static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) -{ - if (!cfs_bandwidth_used()) - return; - - if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0)) - return; - - /* - * it's possible for a throttled entity to be forced into a running - * state (e.g. set_curr_task), in this case we're finished. - */ - if (cfs_rq_throttled(cfs_rq)) - return; - - throttle_cfs_rq(cfs_rq); -} - -static inline u64 default_cfs_period(void); -static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun); -static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b); - -static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer) -{ - struct cfs_bandwidth *cfs_b = - container_of(timer, struct cfs_bandwidth, slack_timer); - do_sched_cfs_slack_timer(cfs_b); - - return HRTIMER_NORESTART; -} - -static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) -{ - struct cfs_bandwidth *cfs_b = - container_of(timer, struct cfs_bandwidth, period_timer); - ktime_t now; - int overrun; - int idle = 0; - - for (;;) { - now = hrtimer_cb_get_time(timer); - overrun = hrtimer_forward(timer, now, cfs_b->period); - - if (!overrun) - break; - - idle = do_sched_cfs_period_timer(cfs_b, overrun); - } - - return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; -} - -void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) -{ - raw_spin_lock_init(&cfs_b->lock); - cfs_b->runtime = 0; - cfs_b->quota = RUNTIME_INF; - cfs_b->period = ns_to_ktime(default_cfs_period()); - - INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq); - hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); - cfs_b->period_timer.function = sched_cfs_period_timer; - hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); - cfs_b->slack_timer.function = sched_cfs_slack_timer; -} - -static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) -{ - cfs_rq->runtime_enabled = 0; - INIT_LIST_HEAD(&cfs_rq->throttled_list); -} - -/* requires cfs_b->lock, may release to reprogram timer */ -void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b) -{ - /* - * The timer may be active because we're trying to set a new bandwidth - * period or because we're racing with the tear-down path - * (timer_active==0 becomes visible before the hrtimer call-back - * terminates). In either case we ensure that it's re-programmed - */ - while (unlikely(hrtimer_active(&cfs_b->period_timer))) { - raw_spin_unlock(&cfs_b->lock); - /* ensure cfs_b->lock is available while we wait */ - hrtimer_cancel(&cfs_b->period_timer); - - raw_spin_lock(&cfs_b->lock); - /* if someone else restarted the timer then we're done */ - if (cfs_b->timer_active) - return; - } - - cfs_b->timer_active = 1; - start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period); -} - -static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) -{ - hrtimer_cancel(&cfs_b->period_timer); - hrtimer_cancel(&cfs_b->slack_timer); -} - -void unthrottle_offline_cfs_rqs(struct rq *rq) -{ - struct cfs_rq *cfs_rq; - - for_each_leaf_cfs_rq(rq, cfs_rq) { - struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); - - if (!cfs_rq->runtime_enabled) - continue; - - /* - * clock_task is not advancing so we just need to make sure - * there's some valid quota amount - */ - cfs_rq->runtime_remaining = cfs_b->quota; - if (cfs_rq_throttled(cfs_rq)) - unthrottle_cfs_rq(cfs_rq); - } -} - -#else /* CONFIG_CFS_BANDWIDTH */ -static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, - unsigned long delta_exec) {} -static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} -static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {} -static void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} - -static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) -{ - return 0; -} - -static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) -{ - return 0; -} - -static inline int throttled_lb_pair(struct task_group *tg, - int src_cpu, int dest_cpu) -{ - return 0; -} - -void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} - -#ifdef CONFIG_FAIR_GROUP_SCHED -static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} -#endif - -static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) -{ - return NULL; -} -static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} -void unthrottle_offline_cfs_rqs(struct rq *rq) {} - -#endif /* CONFIG_CFS_BANDWIDTH */ - -/************************************************** - * CFS operations on tasks: - */ - -#ifdef CONFIG_SCHED_HRTICK -static void hrtick_start_fair(struct rq *rq, struct task_struct *p) -{ - struct sched_entity *se = &p->se; - struct cfs_rq *cfs_rq = cfs_rq_of(se); - - WARN_ON(task_rq(p) != rq); - - if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) { - u64 slice = sched_slice(cfs_rq, se); - u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime; - s64 delta = slice - ran; - - if (delta < 0) { - if (rq->curr == p) - resched_task(p); - return; - } - - /* - * Don't schedule slices shorter than 10000ns, that just - * doesn't make sense. Rely on vruntime for fairness. - */ - if (rq->curr != p) - delta = max_t(s64, 10000LL, delta); - - hrtick_start(rq, delta); - } -} - -/* - * called from enqueue/dequeue and updates the hrtick when the - * current task is from our class and nr_running is low enough - * to matter. - */ -static void hrtick_update(struct rq *rq) -{ - struct task_struct *curr = rq->curr; - - if (curr->sched_class != &fair_sched_class) - return; - - if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency) - hrtick_start_fair(rq, curr); -} -#else /* !CONFIG_SCHED_HRTICK */ -static inline void -hrtick_start_fair(struct rq *rq, struct task_struct *p) -{ -} - -static inline void hrtick_update(struct rq *rq) -{ -} -#endif - -/* - * The enqueue_task method is called before nr_running is - * increased. Here we update the fair scheduling stats and - * then put the task into the rbtree: - */ -static void -enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) -{ - struct cfs_rq *cfs_rq; - struct sched_entity *se = &p->se; - - for_each_sched_entity(se) { - if (se->on_rq) - break; - cfs_rq = cfs_rq_of(se); - enqueue_entity(cfs_rq, se, flags); - - /* - * end evaluation on encountering a throttled cfs_rq - * - * note: in the case of encountering a throttled cfs_rq we will - * post the final h_nr_running increment below. - */ - if (cfs_rq_throttled(cfs_rq)) - break; - cfs_rq->h_nr_running++; - - flags = ENQUEUE_WAKEUP; - } - - for_each_sched_entity(se) { - cfs_rq = cfs_rq_of(se); - cfs_rq->h_nr_running++; - - if (cfs_rq_throttled(cfs_rq)) - break; - - update_cfs_load(cfs_rq, 0); - update_cfs_shares(cfs_rq); - } - - if (!se) - inc_nr_running(rq); - hrtick_update(rq); -} - -static void set_next_buddy(struct sched_entity *se); - -/* - * The dequeue_task method is called before nr_running is - * decreased. We remove the task from the rbtree and - * update the fair scheduling stats: - */ -static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) -{ - struct cfs_rq *cfs_rq; - struct sched_entity *se = &p->se; - int task_sleep = flags & DEQUEUE_SLEEP; - - for_each_sched_entity(se) { - cfs_rq = cfs_rq_of(se); - dequeue_entity(cfs_rq, se, flags); - - /* - * end evaluation on encountering a throttled cfs_rq - * - * note: in the case of encountering a throttled cfs_rq we will - * post the final h_nr_running decrement below. - */ - if (cfs_rq_throttled(cfs_rq)) - break; - cfs_rq->h_nr_running--; - - /* Don't dequeue parent if it has other entities besides us */ - if (cfs_rq->load.weight) { - /* - * Bias pick_next to pick a task from this cfs_rq, as - * p is sleeping when it is within its sched_slice. - */ - if (task_sleep && parent_entity(se)) - set_next_buddy(parent_entity(se)); - - /* avoid re-evaluating load for this entity */ - se = parent_entity(se); - break; - } - flags |= DEQUEUE_SLEEP; - } - - for_each_sched_entity(se) { - cfs_rq = cfs_rq_of(se); - cfs_rq->h_nr_running--; - - if (cfs_rq_throttled(cfs_rq)) - break; - - update_cfs_load(cfs_rq, 0); - update_cfs_shares(cfs_rq); - } - - if (!se) - dec_nr_running(rq); - hrtick_update(rq); -} - -#ifdef CONFIG_SMP -/* Used instead of source_load when we know the type == 0 */ -static unsigned long weighted_cpuload(const int cpu) -{ - return cpu_rq(cpu)->load.weight; -} - -/* - * Return a low guess at the load of a migration-source cpu weighted - * according to the scheduling class and "nice" value. - * - * We want to under-estimate the load of migration sources, to - * balance conservatively. - */ -static unsigned long source_load(int cpu, int type) -{ - struct rq *rq = cpu_rq(cpu); - unsigned long total = weighted_cpuload(cpu); - - if (type == 0 || !sched_feat(LB_BIAS)) - return total; - - return min(rq->cpu_load[type-1], total); -} - -/* - * Return a high guess at the load of a migration-target cpu weighted - * according to the scheduling class and "nice" value. - */ -static unsigned long target_load(int cpu, int type) -{ - struct rq *rq = cpu_rq(cpu); - unsigned long total = weighted_cpuload(cpu); - - if (type == 0 || !sched_feat(LB_BIAS)) - return total; - - return max(rq->cpu_load[type-1], total); -} - -static unsigned long power_of(int cpu) -{ - return cpu_rq(cpu)->cpu_power; -} - -static unsigned long cpu_avg_load_per_task(int cpu) -{ - struct rq *rq = cpu_rq(cpu); - unsigned long nr_running = ACCESS_ONCE(rq->nr_running); - - if (nr_running) - return rq->load.weight / nr_running; - - return 0; -} - - -static void task_waking_fair(struct task_struct *p) -{ - struct sched_entity *se = &p->se; - struct cfs_rq *cfs_rq = cfs_rq_of(se); - u64 min_vruntime; - -#ifndef CONFIG_64BIT - u64 min_vruntime_copy; - - do { - min_vruntime_copy = cfs_rq->min_vruntime_copy; - smp_rmb(); - min_vruntime = cfs_rq->min_vruntime; - } while (min_vruntime != min_vruntime_copy); -#else - min_vruntime = cfs_rq->min_vruntime; -#endif - - se->vruntime -= min_vruntime; -} - -#ifdef CONFIG_FAIR_GROUP_SCHED -/* - * effective_load() calculates the load change as seen from the root_task_group - * - * Adding load to a group doesn't make a group heavier, but can cause movement - * of group shares between cpus. Assuming the shares were perfectly aligned one - * can calculate the shift in shares. - * - * Calculate the effective load difference if @wl is added (subtracted) to @tg - * on this @cpu and results in a total addition (subtraction) of @wg to the - * total group weight. - * - * Given a runqueue weight distribution (rw_i) we can compute a shares - * distribution (s_i) using: - * - * s_i = rw_i / \Sum rw_j (1) - * - * Suppose we have 4 CPUs and our @tg is a direct child of the root group and - * has 7 equal weight tasks, distributed as below (rw_i), with the resulting - * shares distribution (s_i): - * - * rw_i = { 2, 4, 1, 0 } - * s_i = { 2/7, 4/7, 1/7, 0 } - * - * As per wake_affine() we're interested in the load of two CPUs (the CPU the - * task used to run on and the CPU the waker is running on), we need to - * compute the effect of waking a task on either CPU and, in case of a sync - * wakeup, compute the effect of the current task going to sleep. - * - * So for a change of @wl to the local @cpu with an overall group weight change - * of @wl we can compute the new shares distribution (s'_i) using: - * - * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2) - * - * Suppose we're interested in CPUs 0 and 1, and want to compute the load - * differences in waking a task to CPU 0. The additional task changes the - * weight and shares distributions like: - * - * rw'_i = { 3, 4, 1, 0 } - * s'_i = { 3/8, 4/8, 1/8, 0 } - * - * We can then compute the difference in effective weight by using: - * - * dw_i = S * (s'_i - s_i) (3) - * - * Where 'S' is the group weight as seen by its parent. - * - * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7) - * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 - - * 4/7) times the weight of the group. - */ -static long effective_load(struct task_group *tg, int cpu, long wl, long wg) -{ - struct sched_entity *se = tg->se[cpu]; - - if (!tg->parent) /* the trivial, non-cgroup case */ - return wl; - - for_each_sched_entity(se) { - long w, W; - - tg = se->my_q->tg; - - /* - * W = @wg + \Sum rw_j - */ - W = wg + calc_tg_weight(tg, se->my_q); - - /* - * w = rw_i + @wl - */ - w = se->my_q->load.weight + wl; - - /* - * wl = S * s'_i; see (2) - */ - if (W > 0 && w < W) - wl = (w * tg->shares) / W; - else - wl = tg->shares; - - /* - * Per the above, wl is the new se->load.weight value; since - * those are clipped to [MIN_SHARES, ...) do so now. See - * calc_cfs_shares(). - */ - if (wl < MIN_SHARES) - wl = MIN_SHARES; - - /* - * wl = dw_i = S * (s'_i - s_i); see (3) - */ - wl -= se->load.weight; - - /* - * Recursively apply this logic to all parent groups to compute - * the final effective load change on the root group. Since - * only the @tg group gets extra weight, all parent groups can - * only redistribute existing shares. @wl is the shift in shares - * resulting from this level per the above. - */ - wg = 0; - } - - return wl; -} -#else - -static inline unsigned long effective_load(struct task_group *tg, int cpu, - unsigned long wl, unsigned long wg) -{ - return wl; -} - -#endif - -static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) -{ - s64 this_load, load; - int idx, this_cpu, prev_cpu; - unsigned long tl_per_task; - struct task_group *tg; - unsigned long weight; - int balanced; - - idx = sd->wake_idx; - this_cpu = smp_processor_id(); - prev_cpu = task_cpu(p); - load = source_load(prev_cpu, idx); - this_load = target_load(this_cpu, idx); - - /* - * If sync wakeup then subtract the (maximum possible) - * effect of the currently running task from the load - * of the current CPU: - */ - if (sync) { - tg = task_group(current); - weight = current->se.load.weight; - - this_load += effective_load(tg, this_cpu, -weight, -weight); - load += effective_load(tg, prev_cpu, 0, -weight); - } - - tg = task_group(p); - weight = p->se.load.weight; - - /* - * In low-load situations, where prev_cpu is idle and this_cpu is idle - * due to the sync cause above having dropped this_load to 0, we'll - * always have an imbalance, but there's really nothing you can do - * about that, so that's good too. - * - * Otherwise check if either cpus are near enough in load to allow this - * task to be woken on this_cpu. - */ - if (this_load > 0) { - s64 this_eff_load, prev_eff_load; - - this_eff_load = 100; - this_eff_load *= power_of(prev_cpu); - this_eff_load *= this_load + - effective_load(tg, this_cpu, weight, weight); - - prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2; - prev_eff_load *= power_of(this_cpu); - prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight); - - balanced = this_eff_load <= prev_eff_load; - } else - balanced = true; - - /* - * If the currently running task will sleep within - * a reasonable amount of time then attract this newly - * woken task: - */ - if (sync && balanced) - return 1; - - schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts); - tl_per_task = cpu_avg_load_per_task(this_cpu); - - if (balanced || - (this_load <= load && - this_load + target_load(prev_cpu, idx) <= tl_per_task)) { - /* - * This domain has SD_WAKE_AFFINE and - * p is cache cold in this domain, and - * there is no bad imbalance. - */ - schedstat_inc(sd, ttwu_move_affine); - schedstat_inc(p, se.statistics.nr_wakeups_affine); - - return 1; - } - return 0; -} - -/* - * find_idlest_group finds and returns the least busy CPU group within the - * domain. - */ -static struct sched_group * -find_idlest_group(struct sched_domain *sd, struct task_struct *p, - int this_cpu, int load_idx) -{ - struct sched_group *idlest = NULL, *group = sd->groups; - unsigned long min_load = ULONG_MAX, this_load = 0; - int imbalance = 100 + (sd->imbalance_pct-100)/2; - - do { - unsigned long load, avg_load; - int local_group; - int i; - - /* Skip over this group if it has no CPUs allowed */ - if (!cpumask_intersects(sched_group_cpus(group), - tsk_cpus_allowed(p))) - continue; - - local_group = cpumask_test_cpu(this_cpu, - sched_group_cpus(group)); - - /* Tally up the load of all CPUs in the group */ - avg_load = 0; - - for_each_cpu(i, sched_group_cpus(group)) { - /* Bias balancing toward cpus of our domain */ - if (local_group) - load = source_load(i, load_idx); - else - load = target_load(i, load_idx); - - avg_load += load; - } - - /* Adjust by relative CPU power of the group */ - avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power; - - if (local_group) { - this_load = avg_load; - } else if (avg_load < min_load) { - min_load = avg_load; - idlest = group; - } - } while (group = group->next, group != sd->groups); - - if (!idlest || 100*this_load < imbalance*min_load) - return NULL; - return idlest; -} - -/* - * find_idlest_cpu - find the idlest cpu among the cpus in group. - */ -static int -find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) -{ - unsigned long load, min_load = ULONG_MAX; - int idlest = -1; - int i; - - /* Traverse only the allowed CPUs */ - for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) { - load = weighted_cpuload(i); - - if (load < min_load || (load == min_load && i == this_cpu)) { - min_load = load; - idlest = i; - } - } - - return idlest; -} - -/* - * Try and locate an idle CPU in the sched_domain. - */ -static int select_idle_sibling(struct task_struct *p, int target) -{ - int cpu = smp_processor_id(); - int prev_cpu = task_cpu(p); - struct sched_domain *sd; - struct sched_group *sg; - int i, smt = 0; - - /* - * If the task is going to be woken-up on this cpu and if it is - * already idle, then it is the right target. - */ - if (target == cpu && idle_cpu(cpu)) - return cpu; - - /* - * If the task is going to be woken-up on the cpu where it previously - * ran and if it is currently idle, then it the right target. - */ - if (target == prev_cpu && idle_cpu(prev_cpu)) - return prev_cpu; - - /* - * Otherwise, iterate the domains and find an elegible idle cpu. - */ - rcu_read_lock(); -again: - for_each_domain(target, sd) { - if (!smt && (sd->flags & SD_SHARE_CPUPOWER)) - continue; - - if (!(sd->flags & SD_SHARE_PKG_RESOURCES)) { - if (!smt) { - smt = 1; - goto again; - } - break; - } - - sg = sd->groups; - do { - if (!cpumask_intersects(sched_group_cpus(sg), - tsk_cpus_allowed(p))) - goto next; - - for_each_cpu(i, sched_group_cpus(sg)) { - if (!idle_cpu(i)) - goto next; - } - - target = cpumask_first_and(sched_group_cpus(sg), - tsk_cpus_allowed(p)); - goto done; -next: - sg = sg->next; - } while (sg != sd->groups); - } -done: - rcu_read_unlock(); - - return target; -} - -/* - * sched_balance_self: balance the current task (running on cpu) in domains - * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and - * SD_BALANCE_EXEC. - * - * Balance, ie. select the least loaded group. - * - * Returns the target CPU number, or the same CPU if no balancing is needed. - * - * preempt must be disabled. - */ -static int -select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags) -{ - struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL; - int cpu = smp_processor_id(); - int prev_cpu = task_cpu(p); - int new_cpu = cpu; - int want_affine = 0; - int want_sd = 1; - int sync = wake_flags & WF_SYNC; - - if (sd_flag & SD_BALANCE_WAKE) { - if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) - want_affine = 1; - new_cpu = prev_cpu; - } - - rcu_read_lock(); - for_each_domain(cpu, tmp) { - if (!(tmp->flags & SD_LOAD_BALANCE)) - continue; - - /* - * If power savings logic is enabled for a domain, see if we - * are not overloaded, if so, don't balance wider. - */ - if (tmp->flags & (SD_POWERSAVINGS_BALANCE|SD_PREFER_LOCAL)) { - unsigned long power = 0; - unsigned long nr_running = 0; - unsigned long capacity; - int i; - - for_each_cpu(i, sched_domain_span(tmp)) { - power += power_of(i); - nr_running += cpu_rq(i)->cfs.nr_running; - } - - capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE); - - if (tmp->flags & SD_POWERSAVINGS_BALANCE) - nr_running /= 2; - - if (nr_running < capacity) - want_sd = 0; - } - - /* - * If both cpu and prev_cpu are part of this domain, - * cpu is a valid SD_WAKE_AFFINE target. - */ - if (want_affine && (tmp->flags & SD_WAKE_AFFINE) && - cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) { - affine_sd = tmp; - want_affine = 0; - } - - if (!want_sd && !want_affine) - break; - - if (!(tmp->flags & sd_flag)) - continue; - - if (want_sd) - sd = tmp; - } - - if (affine_sd) { - if (cpu == prev_cpu || wake_affine(affine_sd, p, sync)) - prev_cpu = cpu; - - new_cpu = select_idle_sibling(p, prev_cpu); - goto unlock; - } - - while (sd) { - int load_idx = sd->forkexec_idx; - struct sched_group *group; - int weight; - - if (!(sd->flags & sd_flag)) { - sd = sd->child; - continue; - } - - if (sd_flag & SD_BALANCE_WAKE) - load_idx = sd->wake_idx; - - group = find_idlest_group(sd, p, cpu, load_idx); - if (!group) { - sd = sd->child; - continue; - } - - new_cpu = find_idlest_cpu(group, p, cpu); - if (new_cpu == -1 || new_cpu == cpu) { - /* Now try balancing at a lower domain level of cpu */ - sd = sd->child; - continue; - } - - /* Now try balancing at a lower domain level of new_cpu */ - cpu = new_cpu; - weight = sd->span_weight; - sd = NULL; - for_each_domain(cpu, tmp) { - if (weight <= tmp->span_weight) - break; - if (tmp->flags & sd_flag) - sd = tmp; - } - /* while loop will break here if sd == NULL */ - } -unlock: - rcu_read_unlock(); - - return new_cpu; -} -#endif /* CONFIG_SMP */ - -static unsigned long -wakeup_gran(struct sched_entity *curr, struct sched_entity *se) -{ - unsigned long gran = sysctl_sched_wakeup_granularity; - - /* - * Since its curr running now, convert the gran from real-time - * to virtual-time in his units. - * - * By using 'se' instead of 'curr' we penalize light tasks, so - * they get preempted easier. That is, if 'se' < 'curr' then - * the resulting gran will be larger, therefore penalizing the - * lighter, if otoh 'se' > 'curr' then the resulting gran will - * be smaller, again penalizing the lighter task. - * - * This is especially important for buddies when the leftmost - * task is higher priority than the buddy. - */ - return calc_delta_fair(gran, se); -} - -/* - * Should 'se' preempt 'curr'. - * - * |s1 - * |s2 - * |s3 - * g - * |<--->|c - * - * w(c, s1) = -1 - * w(c, s2) = 0 - * w(c, s3) = 1 - * - */ -static int -wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se) -{ - s64 gran, vdiff = curr->vruntime - se->vruntime; - - if (vdiff <= 0) - return -1; - - gran = wakeup_gran(curr, se); - if (vdiff > gran) - return 1; - - return 0; -} - -static void set_last_buddy(struct sched_entity *se) -{ - if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) - return; - - for_each_sched_entity(se) - cfs_rq_of(se)->last = se; -} - -static void set_next_buddy(struct sched_entity *se) -{ - if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) - return; - - for_each_sched_entity(se) - cfs_rq_of(se)->next = se; -} - -static void set_skip_buddy(struct sched_entity *se) -{ - for_each_sched_entity(se) - cfs_rq_of(se)->skip = se; -} - -/* - * Preempt the current task with a newly woken task if needed: - */ -static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) -{ - struct task_struct *curr = rq->curr; - struct sched_entity *se = &curr->se, *pse = &p->se; - struct cfs_rq *cfs_rq = task_cfs_rq(curr); - int scale = cfs_rq->nr_running >= sched_nr_latency; - int next_buddy_marked = 0; - - if (unlikely(se == pse)) - return; - - /* - * This is possible from callers such as pull_task(), in which we - * unconditionally check_prempt_curr() after an enqueue (which may have - * lead to a throttle). This both saves work and prevents false - * next-buddy nomination below. - */ - if (unlikely(throttled_hierarchy(cfs_rq_of(pse)))) - return; - - if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) { - set_next_buddy(pse); - next_buddy_marked = 1; - } - - /* - * We can come here with TIF_NEED_RESCHED already set from new task - * wake up path. - * - * Note: this also catches the edge-case of curr being in a throttled - * group (e.g. via set_curr_task), since update_curr() (in the - * enqueue of curr) will have resulted in resched being set. This - * prevents us from potentially nominating it as a false LAST_BUDDY - * below. - */ - if (test_tsk_need_resched(curr)) - return; - - /* Idle tasks are by definition preempted by non-idle tasks. */ - if (unlikely(curr->policy == SCHED_IDLE) && - likely(p->policy != SCHED_IDLE)) - goto preempt; - - /* - * Batch and idle tasks do not preempt non-idle tasks (their preemption - * is driven by the tick): - */ - if (unlikely(p->policy != SCHED_NORMAL)) - return; - - find_matching_se(&se, &pse); - update_curr(cfs_rq_of(se)); - BUG_ON(!pse); - if (wakeup_preempt_entity(se, pse) == 1) { - /* - * Bias pick_next to pick the sched entity that is - * triggering this preemption. - */ - if (!next_buddy_marked) - set_next_buddy(pse); - goto preempt; - } - - return; - -preempt: - resched_task(curr); - /* - * Only set the backward buddy when the current task is still - * on the rq. This can happen when a wakeup gets interleaved - * with schedule on the ->pre_schedule() or idle_balance() - * point, either of which can * drop the rq lock. - * - * Also, during early boot the idle thread is in the fair class, - * for obvious reasons its a bad idea to schedule back to it. - */ - if (unlikely(!se->on_rq || curr == rq->idle)) - return; - - if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se)) - set_last_buddy(se); -} - -static struct task_struct *pick_next_task_fair(struct rq *rq) -{ - struct task_struct *p; - struct cfs_rq *cfs_rq = &rq->cfs; - struct sched_entity *se; - - if (!cfs_rq->nr_running) - return NULL; - - do { - se = pick_next_entity(cfs_rq); - set_next_entity(cfs_rq, se); - cfs_rq = group_cfs_rq(se); - } while (cfs_rq); - - p = task_of(se); - hrtick_start_fair(rq, p); - - return p; -} - -/* - * Account for a descheduled task: - */ -static void put_prev_task_fair(struct rq *rq, struct task_struct *prev) -{ - struct sched_entity *se = &prev->se; - struct cfs_rq *cfs_rq; - - for_each_sched_entity(se) { - cfs_rq = cfs_rq_of(se); - put_prev_entity(cfs_rq, se); - } -} - -/* - * sched_yield() is very simple - * - * The magic of dealing with the ->skip buddy is in pick_next_entity. - */ -static void yield_task_fair(struct rq *rq) -{ - struct task_struct *curr = rq->curr; - struct cfs_rq *cfs_rq = task_cfs_rq(curr); - struct sched_entity *se = &curr->se; - - /* - * Are we the only task in the tree? - */ - if (unlikely(rq->nr_running == 1)) - return; - - clear_buddies(cfs_rq, se); - - if (curr->policy != SCHED_BATCH) { - update_rq_clock(rq); - /* - * Update run-time statistics of the 'current'. - */ - update_curr(cfs_rq); - } - - set_skip_buddy(se); -} - -static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt) -{ - struct sched_entity *se = &p->se; - - /* throttled hierarchies are not runnable */ - if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se))) - return false; - - /* Tell the scheduler that we'd really like pse to run next. */ - set_next_buddy(se); - - yield_task_fair(rq); - - return true; -} - -#ifdef CONFIG_SMP -/************************************************** - * Fair scheduling class load-balancing methods: - */ - -/* - * pull_task - move a task from a remote runqueue to the local runqueue. - * Both runqueues must be locked. - */ -static void pull_task(struct rq *src_rq, struct task_struct *p, - struct rq *this_rq, int this_cpu) -{ - deactivate_task(src_rq, p, 0); - set_task_cpu(p, this_cpu); - activate_task(this_rq, p, 0); - check_preempt_curr(this_rq, p, 0); -} - -/* - * Is this task likely cache-hot: - */ -static int -task_hot(struct task_struct *p, u64 now, struct sched_domain *sd) -{ - s64 delta; - - if (p->sched_class != &fair_sched_class) - return 0; - - if (unlikely(p->policy == SCHED_IDLE)) - return 0; - - /* - * Buddy candidates are cache hot: - */ - if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running && - (&p->se == cfs_rq_of(&p->se)->next || - &p->se == cfs_rq_of(&p->se)->last)) - return 1; - - if (sysctl_sched_migration_cost == -1) - return 1; - if (sysctl_sched_migration_cost == 0) - return 0; - - delta = now - p->se.exec_start; - - return delta < (s64)sysctl_sched_migration_cost; -} - -/* - * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? - */ -static -int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu, - struct sched_domain *sd, enum cpu_idle_type idle, - int *all_pinned) -{ - int tsk_cache_hot = 0; - /* - * We do not migrate tasks that are: - * 1) running (obviously), or - * 2) cannot be migrated to this CPU due to cpus_allowed, or - * 3) are cache-hot on their current CPU. - */ - if (!cpumask_test_cpu(this_cpu, tsk_cpus_allowed(p))) { - schedstat_inc(p, se.statistics.nr_failed_migrations_affine); - return 0; - } - *all_pinned = 0; - - if (task_running(rq, p)) { - schedstat_inc(p, se.statistics.nr_failed_migrations_running); - return 0; - } - - /* - * Aggressive migration if: - * 1) task is cache cold, or - * 2) too many balance attempts have failed. - */ - - tsk_cache_hot = task_hot(p, rq->clock_task, sd); - if (!tsk_cache_hot || - sd->nr_balance_failed > sd->cache_nice_tries) { -#ifdef CONFIG_SCHEDSTATS - if (tsk_cache_hot) { - schedstat_inc(sd, lb_hot_gained[idle]); - schedstat_inc(p, se.statistics.nr_forced_migrations); - } -#endif - return 1; - } - - if (tsk_cache_hot) { - schedstat_inc(p, se.statistics.nr_failed_migrations_hot); - return 0; - } - return 1; -} - -/* - * move_one_task tries to move exactly one task from busiest to this_rq, as - * part of active balancing operations within "domain". - * Returns 1 if successful and 0 otherwise. - * - * Called with both runqueues locked. - */ -static int -move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest, - struct sched_domain *sd, enum cpu_idle_type idle) -{ - struct task_struct *p, *n; - struct cfs_rq *cfs_rq; - int pinned = 0; - - for_each_leaf_cfs_rq(busiest, cfs_rq) { - list_for_each_entry_safe(p, n, &cfs_rq->tasks, se.group_node) { - if (throttled_lb_pair(task_group(p), - busiest->cpu, this_cpu)) - break; - - if (!can_migrate_task(p, busiest, this_cpu, - sd, idle, &pinned)) - continue; - - pull_task(busiest, p, this_rq, this_cpu); - /* - * Right now, this is only the second place pull_task() - * is called, so we can safely collect pull_task() - * stats here rather than inside pull_task(). - */ - schedstat_inc(sd, lb_gained[idle]); - return 1; - } - } - - return 0; -} - -static unsigned long -balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest, - unsigned long max_load_move, struct sched_domain *sd, - enum cpu_idle_type idle, int *all_pinned, - struct cfs_rq *busiest_cfs_rq) -{ - int loops = 0, pulled = 0; - long rem_load_move = max_load_move; - struct task_struct *p, *n; - - if (max_load_move == 0) - goto out; - - list_for_each_entry_safe(p, n, &busiest_cfs_rq->tasks, se.group_node) { - if (loops++ > sysctl_sched_nr_migrate) - break; - - if ((p->se.load.weight >> 1) > rem_load_move || - !can_migrate_task(p, busiest, this_cpu, sd, idle, - all_pinned)) - continue; - - pull_task(busiest, p, this_rq, this_cpu); - pulled++; - rem_load_move -= p->se.load.weight; - -#ifdef CONFIG_PREEMPT - /* - * NEWIDLE balancing is a source of latency, so preemptible - * kernels will stop after the first task is pulled to minimize - * the critical section. - */ - if (idle == CPU_NEWLY_IDLE) - break; -#endif - - /* - * We only want to steal up to the prescribed amount of - * weighted load. - */ - if (rem_load_move <= 0) - break; - } -out: - /* - * Right now, this is one of only two places pull_task() is called, - * so we can safely collect pull_task() stats here rather than - * inside pull_task(). - */ - schedstat_add(sd, lb_gained[idle], pulled); - - return max_load_move - rem_load_move; -} - -#ifdef CONFIG_FAIR_GROUP_SCHED -/* - * update tg->load_weight by folding this cpu's load_avg - */ -static int update_shares_cpu(struct task_group *tg, int cpu) -{ - struct cfs_rq *cfs_rq; - unsigned long flags; - struct rq *rq; - - if (!tg->se[cpu]) - return 0; - - rq = cpu_rq(cpu); - cfs_rq = tg->cfs_rq[cpu]; - - raw_spin_lock_irqsave(&rq->lock, flags); - - update_rq_clock(rq); - update_cfs_load(cfs_rq, 1); - - /* - * We need to update shares after updating tg->load_weight in - * order to adjust the weight of groups with long running tasks. - */ - update_cfs_shares(cfs_rq); - - raw_spin_unlock_irqrestore(&rq->lock, flags); - - return 0; -} - -static void update_shares(int cpu) -{ - struct cfs_rq *cfs_rq; - struct rq *rq = cpu_rq(cpu); - - rcu_read_lock(); - /* - * Iterates the task_group tree in a bottom up fashion, see - * list_add_leaf_cfs_rq() for details. - */ - for_each_leaf_cfs_rq(rq, cfs_rq) { - /* throttled entities do not contribute to load */ - if (throttled_hierarchy(cfs_rq)) - continue; - - update_shares_cpu(cfs_rq->tg, cpu); - } - rcu_read_unlock(); -} - -/* - * Compute the cpu's hierarchical load factor for each task group. - * This needs to be done in a top-down fashion because the load of a child - * group is a fraction of its parents load. - */ -static int tg_load_down(struct task_group *tg, void *data) -{ - unsigned long load; - long cpu = (long)data; - - if (!tg->parent) { - load = cpu_rq(cpu)->load.weight; - } else { - load = tg->parent->cfs_rq[cpu]->h_load; - load *= tg->se[cpu]->load.weight; - load /= tg->parent->cfs_rq[cpu]->load.weight + 1; - } - - tg->cfs_rq[cpu]->h_load = load; - - return 0; -} - -static void update_h_load(long cpu) -{ - walk_tg_tree(tg_load_down, tg_nop, (void *)cpu); -} - -static unsigned long -load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, - unsigned long max_load_move, - struct sched_domain *sd, enum cpu_idle_type idle, - int *all_pinned) -{ - long rem_load_move = max_load_move; - struct cfs_rq *busiest_cfs_rq; - - rcu_read_lock(); - update_h_load(cpu_of(busiest)); - - for_each_leaf_cfs_rq(busiest, busiest_cfs_rq) { - unsigned long busiest_h_load = busiest_cfs_rq->h_load; - unsigned long busiest_weight = busiest_cfs_rq->load.weight; - u64 rem_load, moved_load; - - /* - * empty group or part of a throttled hierarchy - */ - if (!busiest_cfs_rq->task_weight || - throttled_lb_pair(busiest_cfs_rq->tg, cpu_of(busiest), this_cpu)) - continue; - - rem_load = (u64)rem_load_move * busiest_weight; - rem_load = div_u64(rem_load, busiest_h_load + 1); - - moved_load = balance_tasks(this_rq, this_cpu, busiest, - rem_load, sd, idle, all_pinned, - busiest_cfs_rq); - - if (!moved_load) - continue; - - moved_load *= busiest_h_load; - moved_load = div_u64(moved_load, busiest_weight + 1); - - rem_load_move -= moved_load; - if (rem_load_move < 0) - break; - } - rcu_read_unlock(); - - return max_load_move - rem_load_move; -} -#else -static inline void update_shares(int cpu) -{ -} - -static unsigned long -load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, - unsigned long max_load_move, - struct sched_domain *sd, enum cpu_idle_type idle, - int *all_pinned) -{ - return balance_tasks(this_rq, this_cpu, busiest, - max_load_move, sd, idle, all_pinned, - &busiest->cfs); -} -#endif - -/* - * move_tasks tries to move up to max_load_move weighted load from busiest to - * this_rq, as part of a balancing operation within domain "sd". - * Returns 1 if successful and 0 otherwise. - * - * Called with both runqueues locked. - */ -static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest, - unsigned long max_load_move, - struct sched_domain *sd, enum cpu_idle_type idle, - int *all_pinned) -{ - unsigned long total_load_moved = 0, load_moved; - - do { - load_moved = load_balance_fair(this_rq, this_cpu, busiest, - max_load_move - total_load_moved, - sd, idle, all_pinned); - - total_load_moved += load_moved; - -#ifdef CONFIG_PREEMPT - /* - * NEWIDLE balancing is a source of latency, so preemptible - * kernels will stop after the first task is pulled to minimize - * the critical section. - */ - if (idle == CPU_NEWLY_IDLE && this_rq->nr_running) - break; - - if (raw_spin_is_contended(&this_rq->lock) || - raw_spin_is_contended(&busiest->lock)) - break; -#endif - } while (load_moved && max_load_move > total_load_moved); - - return total_load_moved > 0; -} - -/********** Helpers for find_busiest_group ************************/ -/* - * sd_lb_stats - Structure to store the statistics of a sched_domain - * during load balancing. - */ -struct sd_lb_stats { - struct sched_group *busiest; /* Busiest group in this sd */ - struct sched_group *this; /* Local group in this sd */ - unsigned long total_load; /* Total load of all groups in sd */ - unsigned long total_pwr; /* Total power of all groups in sd */ - unsigned long avg_load; /* Average load across all groups in sd */ - - /** Statistics of this group */ - unsigned long this_load; - unsigned long this_load_per_task; - unsigned long this_nr_running; - unsigned long this_has_capacity; - unsigned int this_idle_cpus; - - /* Statistics of the busiest group */ - unsigned int busiest_idle_cpus; - unsigned long max_load; - unsigned long busiest_load_per_task; - unsigned long busiest_nr_running; - unsigned long busiest_group_capacity; - unsigned long busiest_has_capacity; - unsigned int busiest_group_weight; - - int group_imb; /* Is there imbalance in this sd */ -#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) - int power_savings_balance; /* Is powersave balance needed for this sd */ - struct sched_group *group_min; /* Least loaded group in sd */ - struct sched_group *group_leader; /* Group which relieves group_min */ - unsigned long min_load_per_task; /* load_per_task in group_min */ - unsigned long leader_nr_running; /* Nr running of group_leader */ - unsigned long min_nr_running; /* Nr running of group_min */ -#endif -}; - -/* - * sg_lb_stats - stats of a sched_group required for load_balancing - */ -struct sg_lb_stats { - unsigned long avg_load; /*Avg load across the CPUs of the group */ - unsigned long group_load; /* Total load over the CPUs of the group */ - unsigned long sum_nr_running; /* Nr tasks running in the group */ - unsigned long sum_weighted_load; /* Weighted load of group's tasks */ - unsigned long group_capacity; - unsigned long idle_cpus; - unsigned long group_weight; - int group_imb; /* Is there an imbalance in the group ? */ - int group_has_capacity; /* Is there extra capacity in the group? */ -}; - -/** - * get_sd_load_idx - Obtain the load index for a given sched domain. - * @sd: The sched_domain whose load_idx is to be obtained. - * @idle: The Idle status of the CPU for whose sd load_icx is obtained. - */ -static inline int get_sd_load_idx(struct sched_domain *sd, - enum cpu_idle_type idle) -{ - int load_idx; - - switch (idle) { - case CPU_NOT_IDLE: - load_idx = sd->busy_idx; - break; - - case CPU_NEWLY_IDLE: - load_idx = sd->newidle_idx; - break; - default: - load_idx = sd->idle_idx; - break; - } - - return load_idx; -} - - -#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) -/** - * init_sd_power_savings_stats - Initialize power savings statistics for - * the given sched_domain, during load balancing. - * - * @sd: Sched domain whose power-savings statistics are to be initialized. - * @sds: Variable containing the statistics for sd. - * @idle: Idle status of the CPU at which we're performing load-balancing. - */ -static inline void init_sd_power_savings_stats(struct sched_domain *sd, - struct sd_lb_stats *sds, enum cpu_idle_type idle) -{ - /* - * Busy processors will not participate in power savings - * balance. - */ - if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE)) - sds->power_savings_balance = 0; - else { - sds->power_savings_balance = 1; - sds->min_nr_running = ULONG_MAX; - sds->leader_nr_running = 0; - } -} - -/** - * update_sd_power_savings_stats - Update the power saving stats for a - * sched_domain while performing load balancing. - * - * @group: sched_group belonging to the sched_domain under consideration. - * @sds: Variable containing the statistics of the sched_domain - * @local_group: Does group contain the CPU for which we're performing - * load balancing ? - * @sgs: Variable containing the statistics of the group. - */ -static inline void update_sd_power_savings_stats(struct sched_group *group, - struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs) -{ - - if (!sds->power_savings_balance) - return; - - /* - * If the local group is idle or completely loaded - * no need to do power savings balance at this domain - */ - if (local_group && (sds->this_nr_running >= sgs->group_capacity || - !sds->this_nr_running)) - sds->power_savings_balance = 0; - - /* - * If a group is already running at full capacity or idle, - * don't include that group in power savings calculations - */ - if (!sds->power_savings_balance || - sgs->sum_nr_running >= sgs->group_capacity || - !sgs->sum_nr_running) - return; - - /* - * Calculate the group which has the least non-idle load. - * This is the group from where we need to pick up the load - * for saving power - */ - if ((sgs->sum_nr_running < sds->min_nr_running) || - (sgs->sum_nr_running == sds->min_nr_running && - group_first_cpu(group) > group_first_cpu(sds->group_min))) { - sds->group_min = group; - sds->min_nr_running = sgs->sum_nr_running; - sds->min_load_per_task = sgs->sum_weighted_load / - sgs->sum_nr_running; - } - - /* - * Calculate the group which is almost near its - * capacity but still has some space to pick up some load - * from other group and save more power - */ - if (sgs->sum_nr_running + 1 > sgs->group_capacity) - return; - - if (sgs->sum_nr_running > sds->leader_nr_running || - (sgs->sum_nr_running == sds->leader_nr_running && - group_first_cpu(group) < group_first_cpu(sds->group_leader))) { - sds->group_leader = group; - sds->leader_nr_running = sgs->sum_nr_running; - } -} - -/** - * check_power_save_busiest_group - see if there is potential for some power-savings balance - * @sds: Variable containing the statistics of the sched_domain - * under consideration. - * @this_cpu: Cpu at which we're currently performing load-balancing. - * @imbalance: Variable to store the imbalance. - * - * Description: - * Check if we have potential to perform some power-savings balance. - * If yes, set the busiest group to be the least loaded group in the - * sched_domain, so that it's CPUs can be put to idle. - * - * Returns 1 if there is potential to perform power-savings balance. - * Else returns 0. - */ -static inline int check_power_save_busiest_group(struct sd_lb_stats *sds, - int this_cpu, unsigned long *imbalance) -{ - if (!sds->power_savings_balance) - return 0; - - if (sds->this != sds->group_leader || - sds->group_leader == sds->group_min) - return 0; - - *imbalance = sds->min_load_per_task; - sds->busiest = sds->group_min; - - return 1; - -} -#else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */ -static inline void init_sd_power_savings_stats(struct sched_domain *sd, - struct sd_lb_stats *sds, enum cpu_idle_type idle) -{ - return; -} - -static inline void update_sd_power_savings_stats(struct sched_group *group, - struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs) -{ - return; -} - -static inline int check_power_save_busiest_group(struct sd_lb_stats *sds, - int this_cpu, unsigned long *imbalance) -{ - return 0; -} -#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */ - - -unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu) -{ - return SCHED_POWER_SCALE; -} - -unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu) -{ - return default_scale_freq_power(sd, cpu); -} - -unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu) -{ - unsigned long weight = sd->span_weight; - unsigned long smt_gain = sd->smt_gain; - - smt_gain /= weight; - - return smt_gain; -} - -unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu) -{ - return default_scale_smt_power(sd, cpu); -} - -unsigned long scale_rt_power(int cpu) -{ - struct rq *rq = cpu_rq(cpu); - u64 total, available; - - total = sched_avg_period() + (rq->clock - rq->age_stamp); - - if (unlikely(total < rq->rt_avg)) { - /* Ensures that power won't end up being negative */ - available = 0; - } else { - available = total - rq->rt_avg; - } - - if (unlikely((s64)total < SCHED_POWER_SCALE)) - total = SCHED_POWER_SCALE; - - total >>= SCHED_POWER_SHIFT; - - return div_u64(available, total); -} - -static void update_cpu_power(struct sched_domain *sd, int cpu) -{ - unsigned long weight = sd->span_weight; - unsigned long power = SCHED_POWER_SCALE; - struct sched_group *sdg = sd->groups; - - if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) { - if (sched_feat(ARCH_POWER)) - power *= arch_scale_smt_power(sd, cpu); - else - power *= default_scale_smt_power(sd, cpu); - - power >>= SCHED_POWER_SHIFT; - } - - sdg->sgp->power_orig = power; - - if (sched_feat(ARCH_POWER)) - power *= arch_scale_freq_power(sd, cpu); - else - power *= default_scale_freq_power(sd, cpu); - - power >>= SCHED_POWER_SHIFT; - - power *= scale_rt_power(cpu); - power >>= SCHED_POWER_SHIFT; - - if (!power) - power = 1; - - cpu_rq(cpu)->cpu_power = power; - sdg->sgp->power = power; -} - -void update_group_power(struct sched_domain *sd, int cpu) -{ - struct sched_domain *child = sd->child; - struct sched_group *group, *sdg = sd->groups; - unsigned long power; - - if (!child) { - update_cpu_power(sd, cpu); - return; - } - - power = 0; - - group = child->groups; - do { - power += group->sgp->power; - group = group->next; - } while (group != child->groups); - - sdg->sgp->power = power; -} - -/* - * Try and fix up capacity for tiny siblings, this is needed when - * things like SD_ASYM_PACKING need f_b_g to select another sibling - * which on its own isn't powerful enough. - * - * See update_sd_pick_busiest() and check_asym_packing(). - */ -static inline int -fix_small_capacity(struct sched_domain *sd, struct sched_group *group) -{ - /* - * Only siblings can have significantly less than SCHED_POWER_SCALE - */ - if (!(sd->flags & SD_SHARE_CPUPOWER)) - return 0; - - /* - * If ~90% of the cpu_power is still there, we're good. - */ - if (group->sgp->power * 32 > group->sgp->power_orig * 29) - return 1; - - return 0; -} - -/** - * update_sg_lb_stats - Update sched_group's statistics for load balancing. - * @sd: The sched_domain whose statistics are to be updated. - * @group: sched_group whose statistics are to be updated. - * @this_cpu: Cpu for which load balance is currently performed. - * @idle: Idle status of this_cpu - * @load_idx: Load index of sched_domain of this_cpu for load calc. - * @local_group: Does group contain this_cpu. - * @cpus: Set of cpus considered for load balancing. - * @balance: Should we balance. - * @sgs: variable to hold the statistics for this group. - */ -static inline void update_sg_lb_stats(struct sched_domain *sd, - struct sched_group *group, int this_cpu, - enum cpu_idle_type idle, int load_idx, - int local_group, const struct cpumask *cpus, - int *balance, struct sg_lb_stats *sgs) -{ - unsigned long load, max_cpu_load, min_cpu_load, max_nr_running; - int i; - unsigned int balance_cpu = -1, first_idle_cpu = 0; - unsigned long avg_load_per_task = 0; - - if (local_group) - balance_cpu = group_first_cpu(group); - - /* Tally up the load of all CPUs in the group */ - max_cpu_load = 0; - min_cpu_load = ~0UL; - max_nr_running = 0; - - for_each_cpu_and(i, sched_group_cpus(group), cpus) { - struct rq *rq = cpu_rq(i); - - /* Bias balancing toward cpus of our domain */ - if (local_group) { - if (idle_cpu(i) && !first_idle_cpu) { - first_idle_cpu = 1; - balance_cpu = i; - } - - load = target_load(i, load_idx); - } else { - load = source_load(i, load_idx); - if (load > max_cpu_load) { - max_cpu_load = load; - max_nr_running = rq->nr_running; - } - if (min_cpu_load > load) - min_cpu_load = load; - } - - sgs->group_load += load; - sgs->sum_nr_running += rq->nr_running; - sgs->sum_weighted_load += weighted_cpuload(i); - if (idle_cpu(i)) - sgs->idle_cpus++; - } - - /* - * First idle cpu or the first cpu(busiest) in this sched group - * is eligible for doing load balancing at this and above - * domains. In the newly idle case, we will allow all the cpu's - * to do the newly idle load balance. - */ - if (idle != CPU_NEWLY_IDLE && local_group) { - if (balance_cpu != this_cpu) { - *balance = 0; - return; - } - update_group_power(sd, this_cpu); - } - - /* Adjust by relative CPU power of the group */ - sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power; - - /* - * Consider the group unbalanced when the imbalance is larger - * than the average weight of a task. - * - * APZ: with cgroup the avg task weight can vary wildly and - * might not be a suitable number - should we keep a - * normalized nr_running number somewhere that negates - * the hierarchy? - */ - if (sgs->sum_nr_running) - avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; - - if ((max_cpu_load - min_cpu_load) >= avg_load_per_task && max_nr_running > 1) - sgs->group_imb = 1; - - sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power, - SCHED_POWER_SCALE); - if (!sgs->group_capacity) - sgs->group_capacity = fix_small_capacity(sd, group); - sgs->group_weight = group->group_weight; - - if (sgs->group_capacity > sgs->sum_nr_running) - sgs->group_has_capacity = 1; -} - -/** - * update_sd_pick_busiest - return 1 on busiest group - * @sd: sched_domain whose statistics are to be checked - * @sds: sched_domain statistics - * @sg: sched_group candidate to be checked for being the busiest - * @sgs: sched_group statistics - * @this_cpu: the current cpu - * - * Determine if @sg is a busier group than the previously selected - * busiest group. - */ -static bool update_sd_pick_busiest(struct sched_domain *sd, - struct sd_lb_stats *sds, - struct sched_group *sg, - struct sg_lb_stats *sgs, - int this_cpu) -{ - if (sgs->avg_load <= sds->max_load) - return false; - - if (sgs->sum_nr_running > sgs->group_capacity) - return true; - - if (sgs->group_imb) - return true; - - /* - * ASYM_PACKING needs to move all the work to the lowest - * numbered CPUs in the group, therefore mark all groups - * higher than ourself as busy. - */ - if ((sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running && - this_cpu < group_first_cpu(sg)) { - if (!sds->busiest) - return true; - - if (group_first_cpu(sds->busiest) > group_first_cpu(sg)) - return true; - } - - return false; -} - -/** - * update_sd_lb_stats - Update sched_domain's statistics for load balancing. - * @sd: sched_domain whose statistics are to be updated. - * @this_cpu: Cpu for which load balance is currently performed. - * @idle: Idle status of this_cpu - * @cpus: Set of cpus considered for load balancing. - * @balance: Should we balance. - * @sds: variable to hold the statistics for this sched_domain. - */ -static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu, - enum cpu_idle_type idle, const struct cpumask *cpus, - int *balance, struct sd_lb_stats *sds) -{ - struct sched_domain *child = sd->child; - struct sched_group *sg = sd->groups; - struct sg_lb_stats sgs; - int load_idx, prefer_sibling = 0; - - if (child && child->flags & SD_PREFER_SIBLING) - prefer_sibling = 1; - - init_sd_power_savings_stats(sd, sds, idle); - load_idx = get_sd_load_idx(sd, idle); - - do { - int local_group; - - local_group = cpumask_test_cpu(this_cpu, sched_group_cpus(sg)); - memset(&sgs, 0, sizeof(sgs)); - update_sg_lb_stats(sd, sg, this_cpu, idle, load_idx, - local_group, cpus, balance, &sgs); - - if (local_group && !(*balance)) - return; - - sds->total_load += sgs.group_load; - sds->total_pwr += sg->sgp->power; - - /* - * In case the child domain prefers tasks go to siblings - * first, lower the sg capacity to one so that we'll try - * and move all the excess tasks away. We lower the capacity - * of a group only if the local group has the capacity to fit - * these excess tasks, i.e. nr_running < group_capacity. The - * extra check prevents the case where you always pull from the - * heaviest group when it is already under-utilized (possible - * with a large weight task outweighs the tasks on the system). - */ - if (prefer_sibling && !local_group && sds->this_has_capacity) - sgs.group_capacity = min(sgs.group_capacity, 1UL); - - if (local_group) { - sds->this_load = sgs.avg_load; - sds->this = sg; - sds->this_nr_running = sgs.sum_nr_running; - sds->this_load_per_task = sgs.sum_weighted_load; - sds->this_has_capacity = sgs.group_has_capacity; - sds->this_idle_cpus = sgs.idle_cpus; - } else if (update_sd_pick_busiest(sd, sds, sg, &sgs, this_cpu)) { - sds->max_load = sgs.avg_load; - sds->busiest = sg; - sds->busiest_nr_running = sgs.sum_nr_running; - sds->busiest_idle_cpus = sgs.idle_cpus; - sds->busiest_group_capacity = sgs.group_capacity; - sds->busiest_load_per_task = sgs.sum_weighted_load; - sds->busiest_has_capacity = sgs.group_has_capacity; - sds->busiest_group_weight = sgs.group_weight; - sds->group_imb = sgs.group_imb; - } - - update_sd_power_savings_stats(sg, sds, local_group, &sgs); - sg = sg->next; - } while (sg != sd->groups); -} - -/** - * check_asym_packing - Check to see if the group is packed into the - * sched doman. - * - * This is primarily intended to used at the sibling level. Some - * cores like POWER7 prefer to use lower numbered SMT threads. In the - * case of POWER7, it can move to lower SMT modes only when higher - * threads are idle. When in lower SMT modes, the threads will - * perform better since they share less core resources. Hence when we - * have idle threads, we want them to be the higher ones. - * - * This packing function is run on idle threads. It checks to see if - * the busiest CPU in this domain (core in the P7 case) has a higher - * CPU number than the packing function is being run on. Here we are - * assuming lower CPU number will be equivalent to lower a SMT thread - * number. - * - * Returns 1 when packing is required and a task should be moved to - * this CPU. The amount of the imbalance is returned in *imbalance. - * - * @sd: The sched_domain whose packing is to be checked. - * @sds: Statistics of the sched_domain which is to be packed - * @this_cpu: The cpu at whose sched_domain we're performing load-balance. - * @imbalance: returns amount of imbalanced due to packing. - */ -static int check_asym_packing(struct sched_domain *sd, - struct sd_lb_stats *sds, - int this_cpu, unsigned long *imbalance) -{ - int busiest_cpu; - - if (!(sd->flags & SD_ASYM_PACKING)) - return 0; - - if (!sds->busiest) - return 0; - - busiest_cpu = group_first_cpu(sds->busiest); - if (this_cpu > busiest_cpu) - return 0; - - *imbalance = DIV_ROUND_CLOSEST(sds->max_load * sds->busiest->sgp->power, - SCHED_POWER_SCALE); - return 1; -} - -/** - * fix_small_imbalance - Calculate the minor imbalance that exists - * amongst the groups of a sched_domain, during - * load balancing. - * @sds: Statistics of the sched_domain whose imbalance is to be calculated. - * @this_cpu: The cpu at whose sched_domain we're performing load-balance. - * @imbalance: Variable to store the imbalance. - */ -static inline void fix_small_imbalance(struct sd_lb_stats *sds, - int this_cpu, unsigned long *imbalance) -{ - unsigned long tmp, pwr_now = 0, pwr_move = 0; - unsigned int imbn = 2; - unsigned long scaled_busy_load_per_task; - - if (sds->this_nr_running) { - sds->this_load_per_task /= sds->this_nr_running; - if (sds->busiest_load_per_task > - sds->this_load_per_task) - imbn = 1; - } else - sds->this_load_per_task = - cpu_avg_load_per_task(this_cpu); - - scaled_busy_load_per_task = sds->busiest_load_per_task - * SCHED_POWER_SCALE; - scaled_busy_load_per_task /= sds->busiest->sgp->power; - - if (sds->max_load - sds->this_load + scaled_busy_load_per_task >= - (scaled_busy_load_per_task * imbn)) { - *imbalance = sds->busiest_load_per_task; - return; - } - - /* - * OK, we don't have enough imbalance to justify moving tasks, - * however we may be able to increase total CPU power used by - * moving them. - */ - - pwr_now += sds->busiest->sgp->power * - min(sds->busiest_load_per_task, sds->max_load); - pwr_now += sds->this->sgp->power * - min(sds->this_load_per_task, sds->this_load); - pwr_now /= SCHED_POWER_SCALE; - - /* Amount of load we'd subtract */ - tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) / - sds->busiest->sgp->power; - if (sds->max_load > tmp) - pwr_move += sds->busiest->sgp->power * - min(sds->busiest_load_per_task, sds->max_load - tmp); - - /* Amount of load we'd add */ - if (sds->max_load * sds->busiest->sgp->power < - sds->busiest_load_per_task * SCHED_POWER_SCALE) - tmp = (sds->max_load * sds->busiest->sgp->power) / - sds->this->sgp->power; - else - tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) / - sds->this->sgp->power; - pwr_move += sds->this->sgp->power * - min(sds->this_load_per_task, sds->this_load + tmp); - pwr_move /= SCHED_POWER_SCALE; - - /* Move if we gain throughput */ - if (pwr_move > pwr_now) - *imbalance = sds->busiest_load_per_task; -} - -/** - * calculate_imbalance - Calculate the amount of imbalance present within the - * groups of a given sched_domain during load balance. - * @sds: statistics of the sched_domain whose imbalance is to be calculated. - * @this_cpu: Cpu for which currently load balance is being performed. - * @imbalance: The variable to store the imbalance. - */ -static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu, - unsigned long *imbalance) -{ - unsigned long max_pull, load_above_capacity = ~0UL; - - sds->busiest_load_per_task /= sds->busiest_nr_running; - if (sds->group_imb) { - sds->busiest_load_per_task = - min(sds->busiest_load_per_task, sds->avg_load); - } - - /* - * In the presence of smp nice balancing, certain scenarios can have - * max load less than avg load(as we skip the groups at or below - * its cpu_power, while calculating max_load..) - */ - if (sds->max_load < sds->avg_load) { - *imbalance = 0; - return fix_small_imbalance(sds, this_cpu, imbalance); - } - - if (!sds->group_imb) { - /* - * Don't want to pull so many tasks that a group would go idle. - */ - load_above_capacity = (sds->busiest_nr_running - - sds->busiest_group_capacity); - - load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE); - - load_above_capacity /= sds->busiest->sgp->power; - } - - /* - * We're trying to get all the cpus to the average_load, so we don't - * want to push ourselves above the average load, nor do we wish to - * reduce the max loaded cpu below the average load. At the same time, - * we also don't want to reduce the group load below the group capacity - * (so that we can implement power-savings policies etc). Thus we look - * for the minimum possible imbalance. - * Be careful of negative numbers as they'll appear as very large values - * with unsigned longs. - */ - max_pull = min(sds->max_load - sds->avg_load, load_above_capacity); - - /* How much load to actually move to equalise the imbalance */ - *imbalance = min(max_pull * sds->busiest->sgp->power, - (sds->avg_load - sds->this_load) * sds->this->sgp->power) - / SCHED_POWER_SCALE; - - /* - * if *imbalance is less than the average load per runnable task - * there is no guarantee that any tasks will be moved so we'll have - * a think about bumping its value to force at least one task to be - * moved - */ - if (*imbalance < sds->busiest_load_per_task) - return fix_small_imbalance(sds, this_cpu, imbalance); - -} - -/******* find_busiest_group() helpers end here *********************/ - -/** - * find_busiest_group - Returns the busiest group within the sched_domain - * if there is an imbalance. If there isn't an imbalance, and - * the user has opted for power-savings, it returns a group whose - * CPUs can be put to idle by rebalancing those tasks elsewhere, if - * such a group exists. - * - * Also calculates the amount of weighted load which should be moved - * to restore balance. - * - * @sd: The sched_domain whose busiest group is to be returned. - * @this_cpu: The cpu for which load balancing is currently being performed. - * @imbalance: Variable which stores amount of weighted load which should - * be moved to restore balance/put a group to idle. - * @idle: The idle status of this_cpu. - * @cpus: The set of CPUs under consideration for load-balancing. - * @balance: Pointer to a variable indicating if this_cpu - * is the appropriate cpu to perform load balancing at this_level. - * - * Returns: - the busiest group if imbalance exists. - * - If no imbalance and user has opted for power-savings balance, - * return the least loaded group whose CPUs can be - * put to idle by rebalancing its tasks onto our group. - */ -static struct sched_group * -find_busiest_group(struct sched_domain *sd, int this_cpu, - unsigned long *imbalance, enum cpu_idle_type idle, - const struct cpumask *cpus, int *balance) -{ - struct sd_lb_stats sds; - - memset(&sds, 0, sizeof(sds)); - - /* - * Compute the various statistics relavent for load balancing at - * this level. - */ - update_sd_lb_stats(sd, this_cpu, idle, cpus, balance, &sds); - - /* - * this_cpu is not the appropriate cpu to perform load balancing at - * this level. - */ - if (!(*balance)) - goto ret; - - if ((idle == CPU_IDLE || idle == CPU_NEWLY_IDLE) && - check_asym_packing(sd, &sds, this_cpu, imbalance)) - return sds.busiest; - - /* There is no busy sibling group to pull tasks from */ - if (!sds.busiest || sds.busiest_nr_running == 0) - goto out_balanced; - - sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr; - - /* - * If the busiest group is imbalanced the below checks don't - * work because they assumes all things are equal, which typically - * isn't true due to cpus_allowed constraints and the like. - */ - if (sds.group_imb) - goto force_balance; - - /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */ - if (idle == CPU_NEWLY_IDLE && sds.this_has_capacity && - !sds.busiest_has_capacity) - goto force_balance; - - /* - * If the local group is more busy than the selected busiest group - * don't try and pull any tasks. - */ - if (sds.this_load >= sds.max_load) - goto out_balanced; - - /* - * Don't pull any tasks if this group is already above the domain - * average load. - */ - if (sds.this_load >= sds.avg_load) - goto out_balanced; - - if (idle == CPU_IDLE) { - /* - * This cpu is idle. If the busiest group load doesn't - * have more tasks than the number of available cpu's and - * there is no imbalance between this and busiest group - * wrt to idle cpu's, it is balanced. - */ - if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) && - sds.busiest_nr_running <= sds.busiest_group_weight) - goto out_balanced; - } else { - /* - * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use - * imbalance_pct to be conservative. - */ - if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load) - goto out_balanced; - } - -force_balance: - /* Looks like there is an imbalance. Compute it */ - calculate_imbalance(&sds, this_cpu, imbalance); - return sds.busiest; - -out_balanced: - /* - * There is no obvious imbalance. But check if we can do some balancing - * to save power. - */ - if (check_power_save_busiest_group(&sds, this_cpu, imbalance)) - return sds.busiest; -ret: - *imbalance = 0; - return NULL; -} - -/* - * find_busiest_queue - find the busiest runqueue among the cpus in group. - */ -static struct rq * -find_busiest_queue(struct sched_domain *sd, struct sched_group *group, - enum cpu_idle_type idle, unsigned long imbalance, - const struct cpumask *cpus) -{ - struct rq *busiest = NULL, *rq; - unsigned long max_load = 0; - int i; - - for_each_cpu(i, sched_group_cpus(group)) { - unsigned long power = power_of(i); - unsigned long capacity = DIV_ROUND_CLOSEST(power, - SCHED_POWER_SCALE); - unsigned long wl; - - if (!capacity) - capacity = fix_small_capacity(sd, group); - - if (!cpumask_test_cpu(i, cpus)) - continue; - - rq = cpu_rq(i); - wl = weighted_cpuload(i); - - /* - * When comparing with imbalance, use weighted_cpuload() - * which is not scaled with the cpu power. - */ - if (capacity && rq->nr_running == 1 && wl > imbalance) - continue; - - /* - * For the load comparisons with the other cpu's, consider - * the weighted_cpuload() scaled with the cpu power, so that - * the load can be moved away from the cpu that is potentially - * running at a lower capacity. - */ - wl = (wl * SCHED_POWER_SCALE) / power; - - if (wl > max_load) { - max_load = wl; - busiest = rq; - } - } - - return busiest; -} - -/* - * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but - * so long as it is large enough. - */ -#define MAX_PINNED_INTERVAL 512 - -/* Working cpumask for load_balance and load_balance_newidle. */ -DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask); - -static int need_active_balance(struct sched_domain *sd, int idle, - int busiest_cpu, int this_cpu) -{ - if (idle == CPU_NEWLY_IDLE) { - - /* - * ASYM_PACKING needs to force migrate tasks from busy but - * higher numbered CPUs in order to pack all tasks in the - * lowest numbered CPUs. - */ - if ((sd->flags & SD_ASYM_PACKING) && busiest_cpu > this_cpu) - return 1; - - /* - * The only task running in a non-idle cpu can be moved to this - * cpu in an attempt to completely freeup the other CPU - * package. - * - * The package power saving logic comes from - * find_busiest_group(). If there are no imbalance, then - * f_b_g() will return NULL. However when sched_mc={1,2} then - * f_b_g() will select a group from which a running task may be - * pulled to this cpu in order to make the other package idle. - * If there is no opportunity to make a package idle and if - * there are no imbalance, then f_b_g() will return NULL and no - * action will be taken in load_balance_newidle(). - * - * Under normal task pull operation due to imbalance, there - * will be more than one task in the source run queue and - * move_tasks() will succeed. ld_moved will be true and this - * active balance code will not be triggered. - */ - if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP) - return 0; - } - - return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2); -} - -static int active_load_balance_cpu_stop(void *data); - -/* - * Check this_cpu to ensure it is balanced within domain. Attempt to move - * tasks if there is an imbalance. - */ -static int load_balance(int this_cpu, struct rq *this_rq, - struct sched_domain *sd, enum cpu_idle_type idle, - int *balance) -{ - int ld_moved, all_pinned = 0, active_balance = 0; - struct sched_group *group; - unsigned long imbalance; - struct rq *busiest; - unsigned long flags; - struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask); - - cpumask_copy(cpus, cpu_active_mask); - - schedstat_inc(sd, lb_count[idle]); - -redo: - group = find_busiest_group(sd, this_cpu, &imbalance, idle, - cpus, balance); - - if (*balance == 0) - goto out_balanced; - - if (!group) { - schedstat_inc(sd, lb_nobusyg[idle]); - goto out_balanced; - } - - busiest = find_busiest_queue(sd, group, idle, imbalance, cpus); - if (!busiest) { - schedstat_inc(sd, lb_nobusyq[idle]); - goto out_balanced; - } - - BUG_ON(busiest == this_rq); - - schedstat_add(sd, lb_imbalance[idle], imbalance); - - ld_moved = 0; - if (busiest->nr_running > 1) { - /* - * Attempt to move tasks. If find_busiest_group has found - * an imbalance but busiest->nr_running <= 1, the group is - * still unbalanced. ld_moved simply stays zero, so it is - * correctly treated as an imbalance. - */ - all_pinned = 1; - local_irq_save(flags); - double_rq_lock(this_rq, busiest); - ld_moved = move_tasks(this_rq, this_cpu, busiest, - imbalance, sd, idle, &all_pinned); - double_rq_unlock(this_rq, busiest); - local_irq_restore(flags); - - /* - * some other cpu did the load balance for us. - */ - if (ld_moved && this_cpu != smp_processor_id()) - resched_cpu(this_cpu); - - /* All tasks on this runqueue were pinned by CPU affinity */ - if (unlikely(all_pinned)) { - cpumask_clear_cpu(cpu_of(busiest), cpus); - if (!cpumask_empty(cpus)) - goto redo; - goto out_balanced; - } - } - - if (!ld_moved) { - schedstat_inc(sd, lb_failed[idle]); - /* - * Increment the failure counter only on periodic balance. - * We do not want newidle balance, which can be very - * frequent, pollute the failure counter causing - * excessive cache_hot migrations and active balances. - */ - if (idle != CPU_NEWLY_IDLE) - sd->nr_balance_failed++; - - if (need_active_balance(sd, idle, cpu_of(busiest), this_cpu)) { - raw_spin_lock_irqsave(&busiest->lock, flags); - - /* don't kick the active_load_balance_cpu_stop, - * if the curr task on busiest cpu can't be - * moved to this_cpu - */ - if (!cpumask_test_cpu(this_cpu, - tsk_cpus_allowed(busiest->curr))) { - raw_spin_unlock_irqrestore(&busiest->lock, - flags); - all_pinned = 1; - goto out_one_pinned; - } - - /* - * ->active_balance synchronizes accesses to - * ->active_balance_work. Once set, it's cleared - * only after active load balance is finished. - */ - if (!busiest->active_balance) { - busiest->active_balance = 1; - busiest->push_cpu = this_cpu; - active_balance = 1; - } - raw_spin_unlock_irqrestore(&busiest->lock, flags); - - if (active_balance) - stop_one_cpu_nowait(cpu_of(busiest), - active_load_balance_cpu_stop, busiest, - &busiest->active_balance_work); - - /* - * We've kicked active balancing, reset the failure - * counter. - */ - sd->nr_balance_failed = sd->cache_nice_tries+1; - } - } else - sd->nr_balance_failed = 0; - - if (likely(!active_balance)) { - /* We were unbalanced, so reset the balancing interval */ - sd->balance_interval = sd->min_interval; - } else { - /* - * If we've begun active balancing, start to back off. This - * case may not be covered by the all_pinned logic if there - * is only 1 task on the busy runqueue (because we don't call - * move_tasks). - */ - if (sd->balance_interval < sd->max_interval) - sd->balance_interval *= 2; - } - - goto out; - -out_balanced: - schedstat_inc(sd, lb_balanced[idle]); - - sd->nr_balance_failed = 0; - -out_one_pinned: - /* tune up the balancing interval */ - if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) || - (sd->balance_interval < sd->max_interval)) - sd->balance_interval *= 2; - - ld_moved = 0; -out: - return ld_moved; -} - -/* - * idle_balance is called by schedule() if this_cpu is about to become - * idle. Attempts to pull tasks from other CPUs. - */ -void idle_balance(int this_cpu, struct rq *this_rq) -{ - struct sched_domain *sd; - int pulled_task = 0; - unsigned long next_balance = jiffies + HZ; - - this_rq->idle_stamp = this_rq->clock; - - if (this_rq->avg_idle < sysctl_sched_migration_cost) - return; - - /* - * Drop the rq->lock, but keep IRQ/preempt disabled. - */ - raw_spin_unlock(&this_rq->lock); - - update_shares(this_cpu); - rcu_read_lock(); - for_each_domain(this_cpu, sd) { - unsigned long interval; - int balance = 1; - - if (!(sd->flags & SD_LOAD_BALANCE)) - continue; - - if (sd->flags & SD_BALANCE_NEWIDLE) { - /* If we've pulled tasks over stop searching: */ - pulled_task = load_balance(this_cpu, this_rq, - sd, CPU_NEWLY_IDLE, &balance); - } - - interval = msecs_to_jiffies(sd->balance_interval); - if (time_after(next_balance, sd->last_balance + interval)) - next_balance = sd->last_balance + interval; - if (pulled_task) { - this_rq->idle_stamp = 0; - break; - } - } - rcu_read_unlock(); - - raw_spin_lock(&this_rq->lock); - - if (pulled_task || time_after(jiffies, this_rq->next_balance)) { - /* - * We are going idle. next_balance may be set based on - * a busy processor. So reset next_balance. - */ - this_rq->next_balance = next_balance; - } -} - -/* - * active_load_balance_cpu_stop is run by cpu stopper. It pushes - * running tasks off the busiest CPU onto idle CPUs. It requires at - * least 1 task to be running on each physical CPU where possible, and - * avoids physical / logical imbalances. - */ -static int active_load_balance_cpu_stop(void *data) -{ - struct rq *busiest_rq = data; - int busiest_cpu = cpu_of(busiest_rq); - int target_cpu = busiest_rq->push_cpu; - struct rq *target_rq = cpu_rq(target_cpu); - struct sched_domain *sd; - - raw_spin_lock_irq(&busiest_rq->lock); - - /* make sure the requested cpu hasn't gone down in the meantime */ - if (unlikely(busiest_cpu != smp_processor_id() || - !busiest_rq->active_balance)) - goto out_unlock; - - /* Is there any task to move? */ - if (busiest_rq->nr_running <= 1) - goto out_unlock; - - /* - * This condition is "impossible", if it occurs - * we need to fix it. Originally reported by - * Bjorn Helgaas on a 128-cpu setup. - */ - BUG_ON(busiest_rq == target_rq); - - /* move a task from busiest_rq to target_rq */ - double_lock_balance(busiest_rq, target_rq); - - /* Search for an sd spanning us and the target CPU. */ - rcu_read_lock(); - for_each_domain(target_cpu, sd) { - if ((sd->flags & SD_LOAD_BALANCE) && - cpumask_test_cpu(busiest_cpu, sched_domain_span(sd))) - break; - } - - if (likely(sd)) { - schedstat_inc(sd, alb_count); - - if (move_one_task(target_rq, target_cpu, busiest_rq, - sd, CPU_IDLE)) - schedstat_inc(sd, alb_pushed); - else - schedstat_inc(sd, alb_failed); - } - rcu_read_unlock(); - double_unlock_balance(busiest_rq, target_rq); -out_unlock: - busiest_rq->active_balance = 0; - raw_spin_unlock_irq(&busiest_rq->lock); - return 0; -} - -#ifdef CONFIG_NO_HZ -/* - * idle load balancing details - * - One of the idle CPUs nominates itself as idle load_balancer, while - * entering idle. - * - This idle load balancer CPU will also go into tickless mode when - * it is idle, just like all other idle CPUs - * - When one of the busy CPUs notice that there may be an idle rebalancing - * needed, they will kick the idle load balancer, which then does idle - * load balancing for all the idle CPUs. - */ -static struct { - atomic_t load_balancer; - atomic_t first_pick_cpu; - atomic_t second_pick_cpu; - cpumask_var_t idle_cpus_mask; - cpumask_var_t grp_idle_mask; - unsigned long next_balance; /* in jiffy units */ -} nohz ____cacheline_aligned; - -int get_nohz_load_balancer(void) -{ - return atomic_read(&nohz.load_balancer); -} - -#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) -/** - * lowest_flag_domain - Return lowest sched_domain containing flag. - * @cpu: The cpu whose lowest level of sched domain is to - * be returned. - * @flag: The flag to check for the lowest sched_domain - * for the given cpu. - * - * Returns the lowest sched_domain of a cpu which contains the given flag. - */ -static inline struct sched_domain *lowest_flag_domain(int cpu, int flag) -{ - struct sched_domain *sd; - - for_each_domain(cpu, sd) - if (sd->flags & flag) - break; - - return sd; -} - -/** - * for_each_flag_domain - Iterates over sched_domains containing the flag. - * @cpu: The cpu whose domains we're iterating over. - * @sd: variable holding the value of the power_savings_sd - * for cpu. - * @flag: The flag to filter the sched_domains to be iterated. - * - * Iterates over all the scheduler domains for a given cpu that has the 'flag' - * set, starting from the lowest sched_domain to the highest. - */ -#define for_each_flag_domain(cpu, sd, flag) \ - for (sd = lowest_flag_domain(cpu, flag); \ - (sd && (sd->flags & flag)); sd = sd->parent) - -/** - * is_semi_idle_group - Checks if the given sched_group is semi-idle. - * @ilb_group: group to be checked for semi-idleness - * - * Returns: 1 if the group is semi-idle. 0 otherwise. - * - * We define a sched_group to be semi idle if it has atleast one idle-CPU - * and atleast one non-idle CPU. This helper function checks if the given - * sched_group is semi-idle or not. - */ -static inline int is_semi_idle_group(struct sched_group *ilb_group) -{ - cpumask_and(nohz.grp_idle_mask, nohz.idle_cpus_mask, - sched_group_cpus(ilb_group)); - - /* - * A sched_group is semi-idle when it has atleast one busy cpu - * and atleast one idle cpu. - */ - if (cpumask_empty(nohz.grp_idle_mask)) - return 0; - - if (cpumask_equal(nohz.grp_idle_mask, sched_group_cpus(ilb_group))) - return 0; - - return 1; -} -/** - * find_new_ilb - Finds the optimum idle load balancer for nomination. - * @cpu: The cpu which is nominating a new idle_load_balancer. - * - * Returns: Returns the id of the idle load balancer if it exists, - * Else, returns >= nr_cpu_ids. - * - * This algorithm picks the idle load balancer such that it belongs to a - * semi-idle powersavings sched_domain. The idea is to try and avoid - * completely idle packages/cores just for the purpose of idle load balancing - * when there are other idle cpu's which are better suited for that job. - */ -static int find_new_ilb(int cpu) -{ - struct sched_domain *sd; - struct sched_group *ilb_group; - int ilb = nr_cpu_ids; - - /* - * Have idle load balancer selection from semi-idle packages only - * when power-aware load balancing is enabled - */ - if (!(sched_smt_power_savings || sched_mc_power_savings)) - goto out_done; - - /* - * Optimize for the case when we have no idle CPUs or only one - * idle CPU. Don't walk the sched_domain hierarchy in such cases - */ - if (cpumask_weight(nohz.idle_cpus_mask) < 2) - goto out_done; - - rcu_read_lock(); - for_each_flag_domain(cpu, sd, SD_POWERSAVINGS_BALANCE) { - ilb_group = sd->groups; - - do { - if (is_semi_idle_group(ilb_group)) { - ilb = cpumask_first(nohz.grp_idle_mask); - goto unlock; - } - - ilb_group = ilb_group->next; - - } while (ilb_group != sd->groups); - } -unlock: - rcu_read_unlock(); - -out_done: - return ilb; -} -#else /* (CONFIG_SCHED_MC || CONFIG_SCHED_SMT) */ -static inline int find_new_ilb(int call_cpu) -{ - return nr_cpu_ids; -} -#endif - -/* - * Kick a CPU to do the nohz balancing, if it is time for it. We pick the - * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle - * CPU (if there is one). - */ -static void nohz_balancer_kick(int cpu) -{ - int ilb_cpu; - - nohz.next_balance++; - - ilb_cpu = get_nohz_load_balancer(); - - if (ilb_cpu >= nr_cpu_ids) { - ilb_cpu = cpumask_first(nohz.idle_cpus_mask); - if (ilb_cpu >= nr_cpu_ids) - return; - } - - if (!cpu_rq(ilb_cpu)->nohz_balance_kick) { - cpu_rq(ilb_cpu)->nohz_balance_kick = 1; - - smp_mb(); - /* - * Use smp_send_reschedule() instead of resched_cpu(). - * This way we generate a sched IPI on the target cpu which - * is idle. And the softirq performing nohz idle load balance - * will be run before returning from the IPI. - */ - smp_send_reschedule(ilb_cpu); - } - return; -} - -/* - * This routine will try to nominate the ilb (idle load balancing) - * owner among the cpus whose ticks are stopped. ilb owner will do the idle - * load balancing on behalf of all those cpus. - * - * When the ilb owner becomes busy, we will not have new ilb owner until some - * idle CPU wakes up and goes back to idle or some busy CPU tries to kick - * idle load balancing by kicking one of the idle CPUs. - * - * Ticks are stopped for the ilb owner as well, with busy CPU kicking this - * ilb owner CPU in future (when there is a need for idle load balancing on - * behalf of all idle CPUs). - */ -void select_nohz_load_balancer(int stop_tick) -{ - int cpu = smp_processor_id(); - - if (stop_tick) { - if (!cpu_active(cpu)) { - if (atomic_read(&nohz.load_balancer) != cpu) - return; - - /* - * If we are going offline and still the leader, - * give up! - */ - if (atomic_cmpxchg(&nohz.load_balancer, cpu, - nr_cpu_ids) != cpu) - BUG(); - - return; - } - - cpumask_set_cpu(cpu, nohz.idle_cpus_mask); - - if (atomic_read(&nohz.first_pick_cpu) == cpu) - atomic_cmpxchg(&nohz.first_pick_cpu, cpu, nr_cpu_ids); - if (atomic_read(&nohz.second_pick_cpu) == cpu) - atomic_cmpxchg(&nohz.second_pick_cpu, cpu, nr_cpu_ids); - - if (atomic_read(&nohz.load_balancer) >= nr_cpu_ids) { - int new_ilb; - - /* make me the ilb owner */ - if (atomic_cmpxchg(&nohz.load_balancer, nr_cpu_ids, - cpu) != nr_cpu_ids) - return; - - /* - * Check to see if there is a more power-efficient - * ilb. - */ - new_ilb = find_new_ilb(cpu); - if (new_ilb < nr_cpu_ids && new_ilb != cpu) { - atomic_set(&nohz.load_balancer, nr_cpu_ids); - resched_cpu(new_ilb); - return; - } - return; - } - } else { - if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask)) - return; - - cpumask_clear_cpu(cpu, nohz.idle_cpus_mask); - - if (atomic_read(&nohz.load_balancer) == cpu) - if (atomic_cmpxchg(&nohz.load_balancer, cpu, - nr_cpu_ids) != cpu) - BUG(); - } - return; -} -#endif - -static DEFINE_SPINLOCK(balancing); - -static unsigned long __read_mostly max_load_balance_interval = HZ/10; - -/* - * Scale the max load_balance interval with the number of CPUs in the system. - * This trades load-balance latency on larger machines for less cross talk. - */ -void update_max_interval(void) -{ - max_load_balance_interval = HZ*num_online_cpus()/10; -} - -/* - * It checks each scheduling domain to see if it is due to be balanced, - * and initiates a balancing operation if so. - * - * Balancing parameters are set up in arch_init_sched_domains. - */ -static void rebalance_domains(int cpu, enum cpu_idle_type idle) -{ - int balance = 1; - struct rq *rq = cpu_rq(cpu); - unsigned long interval; - struct sched_domain *sd; - /* Earliest time when we have to do rebalance again */ - unsigned long next_balance = jiffies + 60*HZ; - int update_next_balance = 0; - int need_serialize; - - update_shares(cpu); - - rcu_read_lock(); - for_each_domain(cpu, sd) { - if (!(sd->flags & SD_LOAD_BALANCE)) - continue; - - interval = sd->balance_interval; - if (idle != CPU_IDLE) - interval *= sd->busy_factor; - - /* scale ms to jiffies */ - interval = msecs_to_jiffies(interval); - interval = clamp(interval, 1UL, max_load_balance_interval); - - need_serialize = sd->flags & SD_SERIALIZE; - - if (need_serialize) { - if (!spin_trylock(&balancing)) - goto out; - } - - if (time_after_eq(jiffies, sd->last_balance + interval)) { - if (load_balance(cpu, rq, sd, idle, &balance)) { - /* - * We've pulled tasks over so either we're no - * longer idle. - */ - idle = CPU_NOT_IDLE; - } - sd->last_balance = jiffies; - } - if (need_serialize) - spin_unlock(&balancing); -out: - if (time_after(next_balance, sd->last_balance + interval)) { - next_balance = sd->last_balance + interval; - update_next_balance = 1; - } - - /* - * Stop the load balance at this level. There is another - * CPU in our sched group which is doing load balancing more - * actively. - */ - if (!balance) - break; - } - rcu_read_unlock(); - - /* - * next_balance will be updated only when there is a need. - * When the cpu is attached to null domain for ex, it will not be - * updated. - */ - if (likely(update_next_balance)) - rq->next_balance = next_balance; -} - -#ifdef CONFIG_NO_HZ -/* - * In CONFIG_NO_HZ case, the idle balance kickee will do the - * rebalancing for all the cpus for whom scheduler ticks are stopped. - */ -static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) -{ - struct rq *this_rq = cpu_rq(this_cpu); - struct rq *rq; - int balance_cpu; - - if (idle != CPU_IDLE || !this_rq->nohz_balance_kick) - return; - - for_each_cpu(balance_cpu, nohz.idle_cpus_mask) { - if (balance_cpu == this_cpu) - continue; - - /* - * If this cpu gets work to do, stop the load balancing - * work being done for other cpus. Next load - * balancing owner will pick it up. - */ - if (need_resched()) { - this_rq->nohz_balance_kick = 0; - break; - } - - raw_spin_lock_irq(&this_rq->lock); - update_rq_clock(this_rq); - update_cpu_load(this_rq); - raw_spin_unlock_irq(&this_rq->lock); - - rebalance_domains(balance_cpu, CPU_IDLE); - - rq = cpu_rq(balance_cpu); - if (time_after(this_rq->next_balance, rq->next_balance)) - this_rq->next_balance = rq->next_balance; - } - nohz.next_balance = this_rq->next_balance; - this_rq->nohz_balance_kick = 0; -} - -/* - * Current heuristic for kicking the idle load balancer - * - first_pick_cpu is the one of the busy CPUs. It will kick - * idle load balancer when it has more than one process active. This - * eliminates the need for idle load balancing altogether when we have - * only one running process in the system (common case). - * - If there are more than one busy CPU, idle load balancer may have - * to run for active_load_balance to happen (i.e., two busy CPUs are - * SMT or core siblings and can run better if they move to different - * physical CPUs). So, second_pick_cpu is the second of the busy CPUs - * which will kick idle load balancer as soon as it has any load. - */ -static inline int nohz_kick_needed(struct rq *rq, int cpu) -{ - unsigned long now = jiffies; - int ret; - int first_pick_cpu, second_pick_cpu; - - if (time_before(now, nohz.next_balance)) - return 0; - - if (idle_cpu(cpu)) - return 0; - - first_pick_cpu = atomic_read(&nohz.first_pick_cpu); - second_pick_cpu = atomic_read(&nohz.second_pick_cpu); - - if (first_pick_cpu < nr_cpu_ids && first_pick_cpu != cpu && - second_pick_cpu < nr_cpu_ids && second_pick_cpu != cpu) - return 0; - - ret = atomic_cmpxchg(&nohz.first_pick_cpu, nr_cpu_ids, cpu); - if (ret == nr_cpu_ids || ret == cpu) { - atomic_cmpxchg(&nohz.second_pick_cpu, cpu, nr_cpu_ids); - if (rq->nr_running > 1) - return 1; - } else { - ret = atomic_cmpxchg(&nohz.second_pick_cpu, nr_cpu_ids, cpu); - if (ret == nr_cpu_ids || ret == cpu) { - if (rq->nr_running) - return 1; - } - } - return 0; -} -#else -static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { } -#endif - -/* - * run_rebalance_domains is triggered when needed from the scheduler tick. - * Also triggered for nohz idle balancing (with nohz_balancing_kick set). - */ -static void run_rebalance_domains(struct softirq_action *h) -{ - int this_cpu = smp_processor_id(); - struct rq *this_rq = cpu_rq(this_cpu); - enum cpu_idle_type idle = this_rq->idle_balance ? - CPU_IDLE : CPU_NOT_IDLE; - - rebalance_domains(this_cpu, idle); - - /* - * If this cpu has a pending nohz_balance_kick, then do the - * balancing on behalf of the other idle cpus whose ticks are - * stopped. - */ - nohz_idle_balance(this_cpu, idle); -} - -static inline int on_null_domain(int cpu) -{ - return !rcu_dereference_sched(cpu_rq(cpu)->sd); -} - -/* - * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing. - */ -void trigger_load_balance(struct rq *rq, int cpu) -{ - /* Don't need to rebalance while attached to NULL domain */ - if (time_after_eq(jiffies, rq->next_balance) && - likely(!on_null_domain(cpu))) - raise_softirq(SCHED_SOFTIRQ); -#ifdef CONFIG_NO_HZ - else if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu))) - nohz_balancer_kick(cpu); -#endif -} - -static void rq_online_fair(struct rq *rq) -{ - update_sysctl(); -} - -static void rq_offline_fair(struct rq *rq) -{ - update_sysctl(); -} - -#endif /* CONFIG_SMP */ - -/* - * scheduler tick hitting a task of our scheduling class: - */ -static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) -{ - struct cfs_rq *cfs_rq; - struct sched_entity *se = &curr->se; - - for_each_sched_entity(se) { - cfs_rq = cfs_rq_of(se); - entity_tick(cfs_rq, se, queued); - } -} - -/* - * called on fork with the child task as argument from the parent's context - * - child not yet on the tasklist - * - preemption disabled - */ -static void task_fork_fair(struct task_struct *p) -{ - struct cfs_rq *cfs_rq = task_cfs_rq(current); - struct sched_entity *se = &p->se, *curr = cfs_rq->curr; - int this_cpu = smp_processor_id(); - struct rq *rq = this_rq(); - unsigned long flags; - - raw_spin_lock_irqsave(&rq->lock, flags); - - update_rq_clock(rq); - - if (unlikely(task_cpu(p) != this_cpu)) { - rcu_read_lock(); - __set_task_cpu(p, this_cpu); - rcu_read_unlock(); - } - - update_curr(cfs_rq); - - if (curr) - se->vruntime = curr->vruntime; - place_entity(cfs_rq, se, 1); - - if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) { - /* - * Upon rescheduling, sched_class::put_prev_task() will place - * 'current' within the tree based on its new key value. - */ - swap(curr->vruntime, se->vruntime); - resched_task(rq->curr); - } - - se->vruntime -= cfs_rq->min_vruntime; - - raw_spin_unlock_irqrestore(&rq->lock, flags); -} - -/* - * Priority of the task has changed. Check to see if we preempt - * the current task. - */ -static void -prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio) -{ - if (!p->se.on_rq) - return; - - /* - * Reschedule if we are currently running on this runqueue and - * our priority decreased, or if we are not currently running on - * this runqueue and our priority is higher than the current's - */ - if (rq->curr == p) { - if (p->prio > oldprio) - resched_task(rq->curr); - } else - check_preempt_curr(rq, p, 0); -} - -static void switched_from_fair(struct rq *rq, struct task_struct *p) -{ - struct sched_entity *se = &p->se; - struct cfs_rq *cfs_rq = cfs_rq_of(se); - - /* - * Ensure the task's vruntime is normalized, so that when its - * switched back to the fair class the enqueue_entity(.flags=0) will - * do the right thing. - * - * If it was on_rq, then the dequeue_entity(.flags=0) will already - * have normalized the vruntime, if it was !on_rq, then only when - * the task is sleeping will it still have non-normalized vruntime. - */ - if (!se->on_rq && p->state != TASK_RUNNING) { - /* - * Fix up our vruntime so that the current sleep doesn't - * cause 'unlimited' sleep bonus. - */ - place_entity(cfs_rq, se, 0); - se->vruntime -= cfs_rq->min_vruntime; - } -} - -/* - * We switched to the sched_fair class. - */ -static void switched_to_fair(struct rq *rq, struct task_struct *p) -{ - if (!p->se.on_rq) - return; - - /* - * We were most likely switched from sched_rt, so - * kick off the schedule if running, otherwise just see - * if we can still preempt the current task. - */ - if (rq->curr == p) - resched_task(rq->curr); - else - check_preempt_curr(rq, p, 0); -} - -/* Account for a task changing its policy or group. - * - * This routine is mostly called to set cfs_rq->curr field when a task - * migrates between groups/classes. - */ -static void set_curr_task_fair(struct rq *rq) -{ - struct sched_entity *se = &rq->curr->se; - - for_each_sched_entity(se) { - struct cfs_rq *cfs_rq = cfs_rq_of(se); - - set_next_entity(cfs_rq, se); - /* ensure bandwidth has been allocated on our new cfs_rq */ - account_cfs_rq_runtime(cfs_rq, 0); - } -} - -void init_cfs_rq(struct cfs_rq *cfs_rq) -{ - cfs_rq->tasks_timeline = RB_ROOT; - INIT_LIST_HEAD(&cfs_rq->tasks); - cfs_rq->min_vruntime = (u64)(-(1LL << 20)); -#ifndef CONFIG_64BIT - cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; -#endif -} - -#ifdef CONFIG_FAIR_GROUP_SCHED -static void task_move_group_fair(struct task_struct *p, int on_rq) -{ - /* - * If the task was not on the rq at the time of this cgroup movement - * it must have been asleep, sleeping tasks keep their ->vruntime - * absolute on their old rq until wakeup (needed for the fair sleeper - * bonus in place_entity()). - * - * If it was on the rq, we've just 'preempted' it, which does convert - * ->vruntime to a relative base. - * - * Make sure both cases convert their relative position when migrating - * to another cgroup's rq. This does somewhat interfere with the - * fair sleeper stuff for the first placement, but who cares. - */ - if (!on_rq) - p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime; - set_task_rq(p, task_cpu(p)); - if (!on_rq) - p->se.vruntime += cfs_rq_of(&p->se)->min_vruntime; -} - -void free_fair_sched_group(struct task_group *tg) -{ - int i; - - destroy_cfs_bandwidth(tg_cfs_bandwidth(tg)); - - for_each_possible_cpu(i) { - if (tg->cfs_rq) - kfree(tg->cfs_rq[i]); - if (tg->se) - kfree(tg->se[i]); - } - - kfree(tg->cfs_rq); - kfree(tg->se); -} - -int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) -{ - struct cfs_rq *cfs_rq; - struct sched_entity *se; - int i; - - tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL); - if (!tg->cfs_rq) - goto err; - tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL); - if (!tg->se) - goto err; - - tg->shares = NICE_0_LOAD; - - init_cfs_bandwidth(tg_cfs_bandwidth(tg)); - - for_each_possible_cpu(i) { - cfs_rq = kzalloc_node(sizeof(struct cfs_rq), - GFP_KERNEL, cpu_to_node(i)); - if (!cfs_rq) - goto err; - - se = kzalloc_node(sizeof(struct sched_entity), - GFP_KERNEL, cpu_to_node(i)); - if (!se) - goto err_free_rq; - - init_cfs_rq(cfs_rq); - init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]); - } - - return 1; - -err_free_rq: - kfree(cfs_rq); -err: - return 0; -} - -void unregister_fair_sched_group(struct task_group *tg, int cpu) -{ - struct rq *rq = cpu_rq(cpu); - unsigned long flags; - - /* - * Only empty task groups can be destroyed; so we can speculatively - * check on_list without danger of it being re-added. - */ - if (!tg->cfs_rq[cpu]->on_list) - return; - - raw_spin_lock_irqsave(&rq->lock, flags); - list_del_leaf_cfs_rq(tg->cfs_rq[cpu]); - raw_spin_unlock_irqrestore(&rq->lock, flags); -} - -void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, - struct sched_entity *se, int cpu, - struct sched_entity *parent) -{ - struct rq *rq = cpu_rq(cpu); - - cfs_rq->tg = tg; - cfs_rq->rq = rq; -#ifdef CONFIG_SMP - /* allow initial update_cfs_load() to truncate */ - cfs_rq->load_stamp = 1; -#endif - init_cfs_rq_runtime(cfs_rq); - - tg->cfs_rq[cpu] = cfs_rq; - tg->se[cpu] = se; - - /* se could be NULL for root_task_group */ - if (!se) - return; - - if (!parent) - se->cfs_rq = &rq->cfs; - else - se->cfs_rq = parent->my_q; - - se->my_q = cfs_rq; - update_load_set(&se->load, 0); - se->parent = parent; -} - -static DEFINE_MUTEX(shares_mutex); - -int sched_group_set_shares(struct task_group *tg, unsigned long shares) -{ - int i; - unsigned long flags; - - /* - * We can't change the weight of the root cgroup. - */ - if (!tg->se[0]) - return -EINVAL; - - shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES)); - - mutex_lock(&shares_mutex); - if (tg->shares == shares) - goto done; - - tg->shares = shares; - for_each_possible_cpu(i) { - struct rq *rq = cpu_rq(i); - struct sched_entity *se; - - se = tg->se[i]; - /* Propagate contribution to hierarchy */ - raw_spin_lock_irqsave(&rq->lock, flags); - for_each_sched_entity(se) - update_cfs_shares(group_cfs_rq(se)); - raw_spin_unlock_irqrestore(&rq->lock, flags); - } - -done: - mutex_unlock(&shares_mutex); - return 0; -} -#else /* CONFIG_FAIR_GROUP_SCHED */ - -void free_fair_sched_group(struct task_group *tg) { } - -int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) -{ - return 1; -} - -void unregister_fair_sched_group(struct task_group *tg, int cpu) { } - -#endif /* CONFIG_FAIR_GROUP_SCHED */ - - -static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task) -{ - struct sched_entity *se = &task->se; - unsigned int rr_interval = 0; - - /* - * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise - * idle runqueue: - */ - if (rq->cfs.load.weight) - rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se)); - - return rr_interval; -} - -/* - * All the scheduling class methods: - */ -const struct sched_class fair_sched_class = { - .next = &idle_sched_class, - .enqueue_task = enqueue_task_fair, - .dequeue_task = dequeue_task_fair, - .yield_task = yield_task_fair, - .yield_to_task = yield_to_task_fair, - - .check_preempt_curr = check_preempt_wakeup, - - .pick_next_task = pick_next_task_fair, - .put_prev_task = put_prev_task_fair, - -#ifdef CONFIG_SMP - .select_task_rq = select_task_rq_fair, - - .rq_online = rq_online_fair, - .rq_offline = rq_offline_fair, - - .task_waking = task_waking_fair, -#endif - - .set_curr_task = set_curr_task_fair, - .task_tick = task_tick_fair, - .task_fork = task_fork_fair, - - .prio_changed = prio_changed_fair, - .switched_from = switched_from_fair, - .switched_to = switched_to_fair, - - .get_rr_interval = get_rr_interval_fair, - -#ifdef CONFIG_FAIR_GROUP_SCHED - .task_move_group = task_move_group_fair, -#endif -}; - -#ifdef CONFIG_SCHED_DEBUG -void print_cfs_stats(struct seq_file *m, int cpu) -{ - struct cfs_rq *cfs_rq; - - rcu_read_lock(); - for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) - print_cfs_rq(m, cpu, cfs_rq); - rcu_read_unlock(); -} -#endif - -__init void init_sched_fair_class(void) -{ -#ifdef CONFIG_SMP - open_softirq(SCHED_SOFTIRQ, run_rebalance_domains); - -#ifdef CONFIG_NO_HZ - zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); - alloc_cpumask_var(&nohz.grp_idle_mask, GFP_NOWAIT); - atomic_set(&nohz.load_balancer, nr_cpu_ids); - atomic_set(&nohz.first_pick_cpu, nr_cpu_ids); - atomic_set(&nohz.second_pick_cpu, nr_cpu_ids); -#endif -#endif /* SMP */ - -} |