fair.c 132.7 KB
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/*
 * 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>
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 *
 *  Adaptive scheduling granularity, math enhancements by Peter Zijlstra
 *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
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 */

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#include <linux/latencytop.h>
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#include <linux/sched.h>
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#include <linux/cpumask.h>
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#include <linux/slab.h>
#include <linux/profile.h>
#include <linux/interrupt.h>

#include <trace/events/sched.h>

#include "sched.h"
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/*
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 * Targeted preemption latency for CPU-bound tasks:
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 * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
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 *
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 * NOTE: this latency value is not the same as the concept of
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 * 'timeslice length' - timeslices in CFS are of variable length
 * and have no persistent notion like in traditional, time-slice
 * based scheduling concepts.
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 *
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 * (to see the precise effective timeslice length of your workload,
 *  run vmstat and monitor the context-switches (cs) field)
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 */
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unsigned int sysctl_sched_latency = 6000000ULL;
unsigned int normalized_sysctl_sched_latency = 6000000ULL;
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/*
 * 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;

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/*
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 * Minimal preemption granularity for CPU-bound tasks:
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 * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
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 */
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unsigned int sysctl_sched_min_granularity = 750000ULL;
unsigned int normalized_sysctl_sched_min_granularity = 750000ULL;
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/*
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 * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
 */
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static unsigned int sched_nr_latency = 8;
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/*
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 * After fork, child runs first. If set to 0 (default) then
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 * parent will (try to) run first.
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 */
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unsigned int sysctl_sched_child_runs_first __read_mostly;
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/*
 * SCHED_OTHER wake-up granularity.
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 * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
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 *
 * This option delays the preemption effects of decoupled workloads
 * and reduces their over-scheduling. Synchronous workloads will still
 * have immediate wakeup/sleep latencies.
 */
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unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
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unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
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const_debug unsigned int sysctl_sched_migration_cost = 500000UL;

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/*
 * The exponential sliding  window over which load is averaged for shares
 * distribution.
 * (default: 10msec)
 */
unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;

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#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

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/*
 * 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;
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/**************************************************************
 * CFS operations on generic schedulable entities:
 */

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#ifdef CONFIG_FAIR_GROUP_SCHED
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/* cpu runqueue to which this cfs_rq is attached */
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static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
{
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	return cfs_rq->rq;
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}

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/* An entity is a task if it doesn't "own" a runqueue */
#define entity_is_task(se)	(!se->my_q)
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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);
}

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/* 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;
}

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static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
{
	if (!cfs_rq->on_list) {
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		/*
		 * 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,
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				&rq_of(cfs_rq)->leaf_cfs_rq_list);
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		}
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		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;
	}
}

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/* 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;
}

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/* 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);
	}
}

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#else	/* !CONFIG_FAIR_GROUP_SCHED */

static inline struct task_struct *task_of(struct sched_entity *se)
{
	return container_of(se, struct task_struct, se);
}
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static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
{
	return container_of(cfs_rq, struct rq, cfs);
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}

#define entity_is_task(se)	1

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#define for_each_sched_entity(se) \
		for (; se; se = NULL)
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static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
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{
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	return &task_rq(p)->cfs;
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}

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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;
}

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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)
{
}

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#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;
}

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static inline void
find_matching_se(struct sched_entity **se, struct sched_entity **pse)
{
}

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#endif	/* CONFIG_FAIR_GROUP_SCHED */

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static __always_inline
void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec);
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/**************************************************************
 * Scheduling class tree data structure manipulation methods:
 */

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static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime)
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{
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	s64 delta = (s64)(vruntime - min_vruntime);
	if (delta > 0)
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		min_vruntime = vruntime;

	return min_vruntime;
}

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static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
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{
	s64 delta = (s64)(vruntime - min_vruntime);
	if (delta < 0)
		min_vruntime = vruntime;

	return min_vruntime;
}

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static inline int entity_before(struct sched_entity *a,
				struct sched_entity *b)
{
	return (s64)(a->vruntime - b->vruntime) < 0;
}

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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);

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		if (!cfs_rq->curr)
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			vruntime = se->vruntime;
		else
			vruntime = min_vruntime(vruntime, se->vruntime);
	}

	cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
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#ifndef CONFIG_64BIT
	smp_wmb();
	cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
#endif
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}

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/*
 * Enqueue an entity into the rb-tree:
 */
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static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
	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.
		 */
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		if (entity_before(se, entry)) {
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			link = &parent->rb_left;
		} else {
			link = &parent->rb_right;
			leftmost = 0;
		}
	}

	/*
	 * Maintain a cache of leftmost tree entries (it is frequently
	 * used):
	 */
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	if (leftmost)
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		cfs_rq->rb_leftmost = &se->run_node;
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	rb_link_node(&se->run_node, parent, link);
	rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
}

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static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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	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;
	}
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	rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
}

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struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
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{
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	struct rb_node *left = cfs_rq->rb_leftmost;

	if (!left)
		return NULL;

	return rb_entry(left, struct sched_entity, run_node);
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}

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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
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struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
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{
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	struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
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	if (!last)
		return NULL;
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	return rb_entry(last, struct sched_entity, run_node);
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}

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/**************************************************************
 * Scheduling class statistics methods:
 */

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int sched_proc_update_handler(struct ctl_table *table, int write,
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		void __user *buffer, size_t *lenp,
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		loff_t *ppos)
{
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	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
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	int factor = get_update_sysctl_factor();
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	if (ret || !write)
		return ret;

	sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
					sysctl_sched_min_granularity);

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#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

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	return 0;
}
#endif
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/*
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 * delta /= w
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 */
static inline unsigned long
calc_delta_fair(unsigned long delta, struct sched_entity *se)
{
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	if (unlikely(se->load.weight != NICE_0_LOAD))
		delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load);
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	return delta;
}

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/*
 * The idea is to set a period in which each task runs once.
 *
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 * When there are too many tasks (sched_nr_latency) we have to stretch
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 * this period because otherwise the slices get too small.
 *
 * p = (nr <= nl) ? l : l*nr/nl
 */
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static u64 __sched_period(unsigned long nr_running)
{
	u64 period = sysctl_sched_latency;
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	unsigned long nr_latency = sched_nr_latency;
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	if (unlikely(nr_running > nr_latency)) {
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		period = sysctl_sched_min_granularity;
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		period *= nr_running;
	}

	return period;
}

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/*
 * We calculate the wall-time slice from the period by taking a part
 * proportional to the weight.
 *
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 * s = p*P[w/rw]
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 */
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static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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	u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq);
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	for_each_sched_entity(se) {
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		struct load_weight *load;
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		struct load_weight lw;
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		cfs_rq = cfs_rq_of(se);
		load = &cfs_rq->load;
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		if (unlikely(!se->on_rq)) {
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			lw = cfs_rq->load;
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			update_load_add(&lw, se->load.weight);
			load = &lw;
		}
		slice = calc_delta_mine(slice, se->load.weight, load);
	}
	return slice;
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}

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/*
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 * We calculate the vruntime slice of a to be inserted task
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 *
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 * vs = s/w
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 */
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static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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	return calc_delta_fair(sched_slice(cfs_rq, se), se);
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}

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static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update);
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static void update_cfs_shares(struct cfs_rq *cfs_rq);
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/*
 * Update the current task's runtime statistics. Skip current tasks that
 * are not in our scheduling class.
 */
static inline void
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__update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
	      unsigned long delta_exec)
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{
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	unsigned long delta_exec_weighted;
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	schedstat_set(curr->statistics.exec_max,
		      max((u64)delta_exec, curr->statistics.exec_max));
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	curr->sum_exec_runtime += delta_exec;
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	schedstat_add(cfs_rq, exec_clock, delta_exec);
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	delta_exec_weighted = calc_delta_fair(delta_exec, curr);
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	curr->vruntime += delta_exec_weighted;
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	update_min_vruntime(cfs_rq);
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#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
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	cfs_rq->load_unacc_exec_time += delta_exec;
#endif
682 683
}

684
static void update_curr(struct cfs_rq *cfs_rq)
685
{
686
	struct sched_entity *curr = cfs_rq->curr;
687
	u64 now = rq_of(cfs_rq)->clock_task;
688 689 690 691 692 693 694 695 696 697
	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):
	 */
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	delta_exec = (unsigned long)(now - curr->exec_start);
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	if (!delta_exec)
		return;
701

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	__update_curr(cfs_rq, curr, delta_exec);
	curr->exec_start = now;
704 705 706 707

	if (entity_is_task(curr)) {
		struct task_struct *curtask = task_of(curr);

708
		trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
709
		cpuacct_charge(curtask, delta_exec);
710
		account_group_exec_runtime(curtask, delta_exec);
711
	}
712 713

	account_cfs_rq_runtime(cfs_rq, delta_exec);
714 715 716
}

static inline void
717
update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
718
{
719
	schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock);
720 721 722 723 724
}

/*
 * Task is being enqueued - update stats:
 */
725
static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
726 727 728 729 730
{
	/*
	 * Are we enqueueing a waiting task? (for current tasks
	 * a dequeue/enqueue event is a NOP)
	 */
731
	if (se != cfs_rq->curr)
732
		update_stats_wait_start(cfs_rq, se);
733 734 735
}

static void
736
update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
737
{
738 739 740 741 742
	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);
743 744 745
#ifdef CONFIG_SCHEDSTATS
	if (entity_is_task(se)) {
		trace_sched_stat_wait(task_of(se),
746
			rq_of(cfs_rq)->clock - se->statistics.wait_start);
747 748
	}
#endif
749
	schedstat_set(se->statistics.wait_start, 0);
750 751 752
}

static inline void
753
update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
754 755 756 757 758
{
	/*
	 * Mark the end of the wait period if dequeueing a
	 * waiting task:
	 */
759
	if (se != cfs_rq->curr)
760
		update_stats_wait_end(cfs_rq, se);
761 762 763 764 765 766
}

/*
 * We are picking a new current task - update its stats:
 */
static inline void
767
update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
768 769 770 771
{
	/*
	 * We are starting a new run period:
	 */
772
	se->exec_start = rq_of(cfs_rq)->clock_task;
773 774 775 776 777 778
}

/**************************************************
 * Scheduling class queueing methods:
 */

779 780 781 782
static void
account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
	update_load_add(&cfs_rq->load, se->load.weight);
783
	if (!parent_entity(se))
784
		update_load_add(&rq_of(cfs_rq)->load, se->load.weight);
785 786
#ifdef CONFIG_SMP
	if (entity_is_task(se))
787
		list_add(&se->group_node, &rq_of(cfs_rq)->cfs_tasks);
788
#endif
789 790 791 792 793 794 795
	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);
796
	if (!parent_entity(se))
797
		update_load_sub(&rq_of(cfs_rq)->load, se->load.weight);
798
	if (entity_is_task(se))
799
		list_del_init(&se->group_node);
800 801 802
	cfs_rq->nr_running--;
}

803
#ifdef CONFIG_FAIR_GROUP_SCHED
804 805
/* we need this in update_cfs_load and load-balance functions below */
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
806
# ifdef CONFIG_SMP
807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822
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)
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{
824
	u64 period = sysctl_sched_shares_window;
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	u64 now, delta;
826
	unsigned long load = cfs_rq->load.weight;
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827

828
	if (cfs_rq->tg == &root_task_group || throttled_hierarchy(cfs_rq))
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829 830
		return;

831
	now = rq_of(cfs_rq)->clock_task;
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	delta = now - cfs_rq->load_stamp;

834 835 836 837 838
	/* 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;
839
		delta = period - 1;
840 841
	}

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	cfs_rq->load_stamp = now;
843
	cfs_rq->load_unacc_exec_time = 0;
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	cfs_rq->load_period += delta;
845 846 847 848
	if (load) {
		cfs_rq->load_last = now;
		cfs_rq->load_avg += delta * load;
	}
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850 851 852 853 854
	/* 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);

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	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;
	}
865

866 867
	if (!cfs_rq->curr && !cfs_rq->nr_running && !cfs_rq->load_avg)
		list_del_leaf_cfs_rq(cfs_rq);
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868 869
}

870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885
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;
}

886
static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
887
{
888
	long tg_weight, load, shares;
889

890
	tg_weight = calc_tg_weight(tg, cfs_rq);
891
	load = cfs_rq->load.weight;
892 893

	shares = (tg->shares * load);
894 895
	if (tg_weight)
		shares /= tg_weight;
896 897 898 899 900 901 902 903 904 905 906 907 908

	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);
909
		update_cfs_shares(cfs_rq);
910 911 912 913 914 915 916
	}
}
# else /* CONFIG_SMP */
static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
{
}

917
static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
918 919 920 921 922 923 924 925
{
	return tg->shares;
}

static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
{
}
# endif /* CONFIG_SMP */
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static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
			    unsigned long weight)
{
929 930 931 932
	if (se->on_rq) {
		/* commit outstanding execution time */
		if (cfs_rq->curr == se)
			update_curr(cfs_rq);
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933
		account_entity_dequeue(cfs_rq, se);
934
	}
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935 936 937 938 939 940 941

	update_load_set(&se->load, weight);

	if (se->on_rq)
		account_entity_enqueue(cfs_rq, se);
}

942
static void update_cfs_shares(struct cfs_rq *cfs_rq)
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943 944 945
{
	struct task_group *tg;
	struct sched_entity *se;
946
	long shares;
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947 948 949

	tg = cfs_rq->tg;
	se = tg->se[cpu_of(rq_of(cfs_rq))];
950
	if (!se || throttled_hierarchy(cfs_rq))
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951
		return;
952 953 954 955
#ifndef CONFIG_SMP
	if (likely(se->load.weight == tg->shares))
		return;
#endif
956
	shares = calc_cfs_shares(cfs_rq, tg);
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	reweight_entity(cfs_rq_of(se), se, shares);
}
#else /* CONFIG_FAIR_GROUP_SCHED */
961
static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
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962 963 964
{
}

965
static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
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966 967
{
}
968 969 970 971

static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
{
}
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#endif /* CONFIG_FAIR_GROUP_SCHED */

974
static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
975 976
{
#ifdef CONFIG_SCHEDSTATS
977 978 979 980 981
	struct task_struct *tsk = NULL;

	if (entity_is_task(se))
		tsk = task_of(se);

982 983
	if (se->statistics.sleep_start) {
		u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start;
984 985 986 987

		if ((s64)delta < 0)
			delta = 0;

988 989
		if (unlikely(delta > se->statistics.sleep_max))
			se->statistics.sleep_max = delta;
990

991
		se->statistics.sleep_start = 0;
992
		se->statistics.sum_sleep_runtime += delta;
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Arjan van de Ven 已提交
993

994
		if (tsk) {
995
			account_scheduler_latency(tsk, delta >> 10, 1);
996 997
			trace_sched_stat_sleep(tsk, delta);
		}
998
	}
999 1000
	if (se->statistics.block_start) {
		u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start;
1001 1002 1003 1004

		if ((s64)delta < 0)
			delta = 0;

1005 1006
		if (unlikely(delta > se->statistics.block_max))
			se->statistics.block_max = delta;
1007

1008
		se->statistics.block_start = 0;
1009
		se->statistics.sum_sleep_runtime += delta;
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1010

1011
		if (tsk) {
1012
			if (tsk->in_iowait) {
1013 1014
				se->statistics.iowait_sum += delta;
				se->statistics.iowait_count++;
1015
				trace_sched_stat_iowait(tsk, delta);
1016 1017
			}

1018 1019
			trace_sched_stat_blocked(tsk, delta);

1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030
			/*
			 * 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);
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1031
		}
1032 1033 1034 1035
	}
#endif
}

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1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048
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
}

1049 1050 1051
static void
place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
{
1052
	u64 vruntime = cfs_rq->min_vruntime;
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1053

1054 1055 1056 1057 1058 1059
	/*
	 * 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.
	 */
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1060
	if (initial && sched_feat(START_DEBIT))
1061
		vruntime += sched_vslice(cfs_rq, se);
1062

1063
	/* sleeps up to a single latency don't count. */
1064
	if (!initial) {
1065
		unsigned long thresh = sysctl_sched_latency;
1066

1067 1068 1069 1070 1071 1072
		/*
		 * Halve their sleep time's effect, to allow
		 * for a gentler effect of sleepers:
		 */
		if (sched_feat(GENTLE_FAIR_SLEEPERS))
			thresh >>= 1;
1073

1074
		vruntime -= thresh;
1075 1076
	}

1077 1078 1079
	/* ensure we never gain time by being placed backwards. */
	vruntime = max_vruntime(se->vruntime, vruntime);

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1080
	se->vruntime = vruntime;
1081 1082
}

1083 1084
static void check_enqueue_throttle(struct cfs_rq *cfs_rq);

1085
static void
1086
enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1087
{
1088 1089 1090 1091
	/*
	 * Update the normalized vruntime before updating min_vruntime
	 * through callig update_curr().
	 */
1092
	if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING))
1093 1094
		se->vruntime += cfs_rq->min_vruntime;

1095
	/*
1096
	 * Update run-time statistics of the 'current'.
1097
	 */
1098
	update_curr(cfs_rq);
1099
	update_cfs_load(cfs_rq, 0);
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1100
	account_entity_enqueue(cfs_rq, se);
1101
	update_cfs_shares(cfs_rq);
1102

1103
	if (flags & ENQUEUE_WAKEUP) {
1104
		place_entity(cfs_rq, se, 0);
1105
		enqueue_sleeper(cfs_rq, se);
I
Ingo Molnar 已提交
1106
	}
1107

1108
	update_stats_enqueue(cfs_rq, se);
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1109
	check_spread(cfs_rq, se);
1110 1111
	if (se != cfs_rq->curr)
		__enqueue_entity(cfs_rq, se);
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1112
	se->on_rq = 1;
1113

1114
	if (cfs_rq->nr_running == 1) {
1115
		list_add_leaf_cfs_rq(cfs_rq);
1116 1117
		check_enqueue_throttle(cfs_rq);
	}
1118 1119
}

1120
static void __clear_buddies_last(struct sched_entity *se)
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Peter Zijlstra 已提交
1121
{
1122 1123 1124 1125 1126 1127 1128 1129
	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;
	}
}
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1130

1131 1132 1133 1134 1135 1136 1137 1138 1139
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;
	}
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1140 1141
}

1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152
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;
	}
}

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1153 1154
static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
1155 1156 1157 1158 1159
	if (cfs_rq->last == se)
		__clear_buddies_last(se);

	if (cfs_rq->next == se)
		__clear_buddies_next(se);
1160 1161 1162

	if (cfs_rq->skip == se)
		__clear_buddies_skip(se);
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1163 1164
}

1165
static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
1166

1167
static void
1168
dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1169
{
1170 1171 1172 1173 1174
	/*
	 * Update run-time statistics of the 'current'.
	 */
	update_curr(cfs_rq);

1175
	update_stats_dequeue(cfs_rq, se);
1176
	if (flags & DEQUEUE_SLEEP) {
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1177
#ifdef CONFIG_SCHEDSTATS
1178 1179 1180 1181
		if (entity_is_task(se)) {
			struct task_struct *tsk = task_of(se);

			if (tsk->state & TASK_INTERRUPTIBLE)
1182
				se->statistics.sleep_start = rq_of(cfs_rq)->clock;
1183
			if (tsk->state & TASK_UNINTERRUPTIBLE)
1184
				se->statistics.block_start = rq_of(cfs_rq)->clock;
1185
		}
1186
#endif
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1187 1188
	}

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1189
	clear_buddies(cfs_rq, se);
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1190

1191
	if (se != cfs_rq->curr)
1192
		__dequeue_entity(cfs_rq, se);
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1193
	se->on_rq = 0;
1194
	update_cfs_load(cfs_rq, 0);
1195
	account_entity_dequeue(cfs_rq, se);
1196 1197 1198 1199 1200 1201

	/*
	 * 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.
	 */
1202
	if (!(flags & DEQUEUE_SLEEP))
1203
		se->vruntime -= cfs_rq->min_vruntime;
1204

1205 1206 1207
	/* return excess runtime on last dequeue */
	return_cfs_rq_runtime(cfs_rq);

1208 1209
	update_min_vruntime(cfs_rq);
	update_cfs_shares(cfs_rq);
1210 1211 1212 1213 1214
}

/*
 * Preempt the current task with a newly woken task if needed:
 */
1215
static void
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1216
check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
1217
{
1218
	unsigned long ideal_runtime, delta_exec;
1219 1220
	struct sched_entity *se;
	s64 delta;
1221

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1222
	ideal_runtime = sched_slice(cfs_rq, curr);
1223
	delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
1224
	if (delta_exec > ideal_runtime) {
1225
		resched_task(rq_of(cfs_rq)->curr);
1226 1227 1228 1229 1230
		/*
		 * The current task ran long enough, ensure it doesn't get
		 * re-elected due to buddy favours.
		 */
		clear_buddies(cfs_rq, curr);
1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241
		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;

1242 1243
	se = __pick_first_entity(cfs_rq);
	delta = curr->vruntime - se->vruntime;
1244

1245 1246
	if (delta < 0)
		return;
1247

1248 1249
	if (delta > ideal_runtime)
		resched_task(rq_of(cfs_rq)->curr);
1250 1251
}

1252
static void
1253
set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
1254
{
1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265
	/* '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);
	}

1266
	update_stats_curr_start(cfs_rq, se);
1267
	cfs_rq->curr = se;
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Ingo Molnar 已提交
1268 1269 1270 1271 1272 1273
#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):
	 */
1274
	if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
1275
		se->statistics.slice_max = max(se->statistics.slice_max,
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Ingo Molnar 已提交
1276 1277 1278
			se->sum_exec_runtime - se->prev_sum_exec_runtime);
	}
#endif
1279
	se->prev_sum_exec_runtime = se->sum_exec_runtime;
1280 1281
}

1282 1283 1284
static int
wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);

1285 1286 1287 1288 1289 1290 1291
/*
 * 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
 */
1292
static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
1293
{
1294
	struct sched_entity *se = __pick_first_entity(cfs_rq);
1295
	struct sched_entity *left = se;
1296

1297 1298 1299 1300 1301 1302 1303 1304 1305
	/*
	 * 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;
	}
1306

1307 1308 1309 1310 1311 1312
	/*
	 * 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;

1313 1314 1315 1316 1317 1318
	/*
	 * 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;

1319
	clear_buddies(cfs_rq, se);
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1320 1321

	return se;
1322 1323
}

1324 1325
static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq);

1326
static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
1327 1328 1329 1330 1331 1332
{
	/*
	 * If still on the runqueue then deactivate_task()
	 * was not called and update_curr() has to be done:
	 */
	if (prev->on_rq)
1333
		update_curr(cfs_rq);
1334

1335 1336 1337
	/* throttle cfs_rqs exceeding runtime */
	check_cfs_rq_runtime(cfs_rq);

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Peter Zijlstra 已提交
1338
	check_spread(cfs_rq, prev);
1339
	if (prev->on_rq) {
1340
		update_stats_wait_start(cfs_rq, prev);
1341 1342 1343
		/* Put 'current' back into the tree. */
		__enqueue_entity(cfs_rq, prev);
	}
1344
	cfs_rq->curr = NULL;
1345 1346
}

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1347 1348
static void
entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
1349 1350
{
	/*
1351
	 * Update run-time statistics of the 'current'.
1352
	 */
1353
	update_curr(cfs_rq);
1354

1355 1356 1357 1358 1359
	/*
	 * Update share accounting for long-running entities.
	 */
	update_entity_shares_tick(cfs_rq);

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1360 1361 1362 1363 1364
#ifdef CONFIG_SCHED_HRTICK
	/*
	 * queued ticks are scheduled to match the slice, so don't bother
	 * validating it and just reschedule.
	 */
1365 1366 1367 1368
	if (queued) {
		resched_task(rq_of(cfs_rq)->curr);
		return;
	}
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	/*
	 * 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

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	if (cfs_rq->nr_running > 1)
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Ingo Molnar 已提交
1378
		check_preempt_tick(cfs_rq, curr);
1379 1380
}

1381 1382 1383 1384 1385 1386

/**************************************************
 * CFS bandwidth control machinery
 */

#ifdef CONFIG_CFS_BANDWIDTH
1387 1388

#ifdef HAVE_JUMP_LABEL
1389
static struct static_key __cfs_bandwidth_used;
1390 1391 1392

static inline bool cfs_bandwidth_used(void)
{
1393
	return static_key_false(&__cfs_bandwidth_used);
1394 1395 1396 1397 1398 1399
}

void account_cfs_bandwidth_used(int enabled, int was_enabled)
{
	/* only need to count groups transitioning between enabled/!enabled */
	if (enabled && !was_enabled)
1400
		static_key_slow_inc(&__cfs_bandwidth_used);
1401
	else if (!enabled && was_enabled)
1402
		static_key_slow_dec(&__cfs_bandwidth_used);
1403 1404 1405 1406 1407 1408 1409 1410 1411 1412
}
#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 */

1413 1414 1415 1416 1417 1418 1419 1420
/*
 * default period for cfs group bandwidth.
 * default: 0.1s, units: nanoseconds
 */
static inline u64 default_cfs_period(void)
{
	return 100000000ULL;
}
1421 1422 1423 1424 1425 1426

static inline u64 sched_cfs_bandwidth_slice(void)
{
	return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
}

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1427 1428 1429 1430 1431 1432 1433
/*
 * 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
 */
1434
void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
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1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445
{
	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);
}

1446 1447 1448 1449 1450
static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
{
	return &tg->cfs_bandwidth;
}

1451 1452
/* returns 0 on failure to allocate runtime */
static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
1453 1454 1455
{
	struct task_group *tg = cfs_rq->tg;
	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
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Paul Turner 已提交
1456
	u64 amount = 0, min_amount, expires;
1457 1458 1459 1460 1461 1462 1463

	/* 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;
1464
	else {
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1465 1466 1467 1468 1469 1470 1471 1472
		/*
		 * 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);
1473
			__start_cfs_bandwidth(cfs_b);
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1474
		}
1475 1476 1477 1478 1479 1480

		if (cfs_b->runtime > 0) {
			amount = min(cfs_b->runtime, min_amount);
			cfs_b->runtime -= amount;
			cfs_b->idle = 0;
		}
1481
	}
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1482
	expires = cfs_b->runtime_expires;
1483 1484 1485
	raw_spin_unlock(&cfs_b->lock);

	cfs_rq->runtime_remaining += amount;
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1486 1487 1488 1489 1490 1491 1492
	/*
	 * 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;
1493 1494

	return cfs_rq->runtime_remaining > 0;
1495 1496
}

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1497 1498 1499 1500 1501
/*
 * 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)
1502
{
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1503 1504 1505 1506 1507
	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))
1508 1509
		return;

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1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534
	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) */
1535
	cfs_rq->runtime_remaining -= delta_exec;
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Paul Turner 已提交
1536 1537 1538
	expire_cfs_rq_runtime(cfs_rq);

	if (likely(cfs_rq->runtime_remaining > 0))
1539 1540
		return;

1541 1542 1543 1544 1545 1546
	/*
	 * 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);
1547 1548
}

1549 1550
static __always_inline
void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec)
1551
{
1552
	if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
1553 1554 1555 1556 1557
		return;

	__account_cfs_rq_runtime(cfs_rq, delta_exec);
}

1558 1559
static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
{
1560
	return cfs_bandwidth_used() && cfs_rq->throttled;
1561 1562
}

1563 1564 1565
/* check whether cfs_rq, or any parent, is throttled */
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
{
1566
	return cfs_bandwidth_used() && cfs_rq->throttle_count;
1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621
}

/*
 * 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;
}

1622
static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
1623 1624 1625 1626 1627 1628 1629 1630 1631
{
	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 */
1632 1633 1634
	rcu_read_lock();
	walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
	rcu_read_unlock();
1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654

	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;
1655
	cfs_rq->throttled_timestamp = rq->clock;
1656 1657 1658 1659 1660
	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);
}

1661
void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672
{
	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);
1673
	cfs_b->throttled_time += rq->clock - cfs_rq->throttled_timestamp;
1674 1675
	list_del_rcu(&cfs_rq->throttled_list);
	raw_spin_unlock(&cfs_b->lock);
1676
	cfs_rq->throttled_timestamp = 0;
1677

1678 1679 1680 1681
	update_rq_clock(rq);
	/* update hierarchical throttle state */
	walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);

1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744
	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;
}

1745 1746 1747 1748 1749 1750 1751 1752
/*
 * 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)
{
1753 1754
	u64 runtime, runtime_expires;
	int idle = 1, throttled;
1755 1756 1757 1758 1759 1760

	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;

1761 1762 1763
	throttled = !list_empty(&cfs_b->throttled_cfs_rq);
	/* idle depends on !throttled (for the case of a large deficit) */
	idle = cfs_b->idle && !throttled;
1764
	cfs_b->nr_periods += overrun;
1765

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Paul Turner 已提交
1766 1767 1768 1769 1770 1771
	/* if we're going inactive then everything else can be deferred */
	if (idle)
		goto out_unlock;

	__refill_cfs_bandwidth_runtime(cfs_b);

1772 1773 1774 1775 1776 1777
	if (!throttled) {
		/* mark as potentially idle for the upcoming period */
		cfs_b->idle = 1;
		goto out_unlock;
	}

1778 1779 1780
	/* account preceding periods in which throttling occurred */
	cfs_b->nr_throttled += overrun;

1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804
	/*
	 * 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);
	}
1805

1806 1807 1808 1809 1810 1811 1812 1813 1814
	/* 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;
1815 1816 1817 1818 1819 1820 1821
out_unlock:
	if (idle)
		cfs_b->timer_active = 0;
	raw_spin_unlock(&cfs_b->lock);

	return idle;
}
1822

1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886
/* 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)
{
1887 1888 1889
	if (!cfs_bandwidth_used())
		return;

1890
	if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927
		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);
}

1928 1929 1930 1931 1932 1933 1934
/*
 * 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)
{
1935 1936 1937
	if (!cfs_bandwidth_used())
		return;

1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954
	/* 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)
{
1955 1956 1957
	if (!cfs_bandwidth_used())
		return;

1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969
	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);
}
1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054

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);
}

2055
static void unthrottle_offline_cfs_rqs(struct rq *rq)
2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075
{
	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 */
2076 2077
static __always_inline
void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec) {}
2078 2079
static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
2080
static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2081 2082 2083 2084 2085

static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
{
	return 0;
}
2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096

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;
}
2097 2098 2099 2100 2101

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) {}
2102 2103
#endif

2104 2105 2106 2107 2108
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) {}
2109
static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
2110 2111 2112

#endif /* CONFIG_CFS_BANDWIDTH */

2113 2114 2115 2116
/**************************************************
 * CFS operations on tasks:
 */

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#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);

2125
	if (cfs_rq->nr_running > 1) {
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2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139
		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.
		 */
2140
		if (rq->curr != p)
2141
			delta = max_t(s64, 10000LL, delta);
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2142

2143
		hrtick_start(rq, delta);
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2144 2145
	}
}
2146 2147 2148 2149 2150 2151 2152 2153 2154 2155

/*
 * 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;

2156
	if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class)
2157 2158 2159 2160 2161
		return;

	if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
		hrtick_start_fair(rq, curr);
}
2162
#else /* !CONFIG_SCHED_HRTICK */
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2163 2164 2165 2166
static inline void
hrtick_start_fair(struct rq *rq, struct task_struct *p)
{
}
2167 2168 2169 2170

static inline void hrtick_update(struct rq *rq)
{
}
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#endif

2173 2174 2175 2176 2177
/*
 * 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:
 */
2178
static void
2179
enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
2180 2181
{
	struct cfs_rq *cfs_rq;
2182
	struct sched_entity *se = &p->se;
2183 2184

	for_each_sched_entity(se) {
2185
		if (se->on_rq)
2186 2187
			break;
		cfs_rq = cfs_rq_of(se);
2188
		enqueue_entity(cfs_rq, se, flags);
2189 2190 2191 2192 2193 2194 2195 2196 2197

		/*
		 * 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;
2198
		cfs_rq->h_nr_running++;
2199

2200
		flags = ENQUEUE_WAKEUP;
2201
	}
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2202

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2203
	for_each_sched_entity(se) {
2204
		cfs_rq = cfs_rq_of(se);
2205
		cfs_rq->h_nr_running++;
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2207 2208 2209
		if (cfs_rq_throttled(cfs_rq))
			break;

2210
		update_cfs_load(cfs_rq, 0);
2211
		update_cfs_shares(cfs_rq);
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2212 2213
	}

2214 2215
	if (!se)
		inc_nr_running(rq);
2216
	hrtick_update(rq);
2217 2218
}

2219 2220
static void set_next_buddy(struct sched_entity *se);

2221 2222 2223 2224 2225
/*
 * The dequeue_task method is called before nr_running is
 * decreased. We remove the task from the rbtree and
 * update the fair scheduling stats:
 */
2226
static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
2227 2228
{
	struct cfs_rq *cfs_rq;
2229
	struct sched_entity *se = &p->se;
2230
	int task_sleep = flags & DEQUEUE_SLEEP;
2231 2232 2233

	for_each_sched_entity(se) {
		cfs_rq = cfs_rq_of(se);
2234
		dequeue_entity(cfs_rq, se, flags);
2235 2236 2237 2238 2239 2240 2241 2242 2243

		/*
		 * 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;
2244
		cfs_rq->h_nr_running--;
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2245

2246
		/* Don't dequeue parent if it has other entities besides us */
2247 2248 2249 2250 2251 2252 2253
		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));
2254 2255 2256

			/* avoid re-evaluating load for this entity */
			se = parent_entity(se);
2257
			break;
2258
		}
2259
		flags |= DEQUEUE_SLEEP;
2260
	}
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2261

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2262
	for_each_sched_entity(se) {
2263
		cfs_rq = cfs_rq_of(se);
2264
		cfs_rq->h_nr_running--;
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2266 2267 2268
		if (cfs_rq_throttled(cfs_rq))
			break;

2269
		update_cfs_load(cfs_rq, 0);
2270
		update_cfs_shares(cfs_rq);
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2271 2272
	}

2273 2274
	if (!se)
		dec_nr_running(rq);
2275
	hrtick_update(rq);
2276 2277
}

2278
#ifdef CONFIG_SMP
2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333
/* 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;
}

2334

2335
static void task_waking_fair(struct task_struct *p)
2336 2337 2338
{
	struct sched_entity *se = &p->se;
	struct cfs_rq *cfs_rq = cfs_rq_of(se);
2339 2340 2341 2342
	u64 min_vruntime;

#ifndef CONFIG_64BIT
	u64 min_vruntime_copy;
2343

2344 2345 2346 2347 2348 2349 2350 2351
	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
2352

2353
	se->vruntime -= min_vruntime;
2354 2355
}

2356
#ifdef CONFIG_FAIR_GROUP_SCHED
2357 2358 2359 2360 2361 2362
/*
 * 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.
2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405
 *
 * 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.
2406
 */
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2407
static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
2408
{
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2409
	struct sched_entity *se = tg->se[cpu];
2410

2411
	if (!tg->parent)	/* the trivial, non-cgroup case */
2412 2413
		return wl;

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2414
	for_each_sched_entity(se) {
2415
		long w, W;
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2416

2417
		tg = se->my_q->tg;
2418

2419 2420 2421 2422
		/*
		 * W = @wg + \Sum rw_j
		 */
		W = wg + calc_tg_weight(tg, se->my_q);
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2423

2424 2425 2426 2427
		/*
		 * w = rw_i + @wl
		 */
		w = se->my_q->load.weight + wl;
2428

2429 2430 2431 2432 2433
		/*
		 * wl = S * s'_i; see (2)
		 */
		if (W > 0 && w < W)
			wl = (w * tg->shares) / W;
2434 2435
		else
			wl = tg->shares;
2436

2437 2438 2439 2440 2441
		/*
		 * 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().
		 */
2442 2443
		if (wl < MIN_SHARES)
			wl = MIN_SHARES;
2444 2445 2446 2447

		/*
		 * wl = dw_i = S * (s'_i - s_i); see (3)
		 */
2448
		wl -= se->load.weight;
2449 2450 2451 2452 2453 2454 2455 2456

		/*
		 * 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.
		 */
P
Peter Zijlstra 已提交
2457 2458
		wg = 0;
	}
2459

P
Peter Zijlstra 已提交
2460
	return wl;
2461 2462
}
#else
P
Peter Zijlstra 已提交
2463

2464 2465
static inline unsigned long effective_load(struct task_group *tg, int cpu,
		unsigned long wl, unsigned long wg)
P
Peter Zijlstra 已提交
2466
{
2467
	return wl;
2468
}
P
Peter Zijlstra 已提交
2469

2470 2471
#endif

2472
static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
2473
{
2474
	s64 this_load, load;
2475
	int idx, this_cpu, prev_cpu;
2476
	unsigned long tl_per_task;
2477
	struct task_group *tg;
2478
	unsigned long weight;
2479
	int balanced;
2480

2481 2482 2483 2484 2485
	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);
2486

2487 2488 2489 2490 2491
	/*
	 * If sync wakeup then subtract the (maximum possible)
	 * effect of the currently running task from the load
	 * of the current CPU:
	 */
2492 2493 2494 2495
	if (sync) {
		tg = task_group(current);
		weight = current->se.load.weight;

2496
		this_load += effective_load(tg, this_cpu, -weight, -weight);
2497 2498
		load += effective_load(tg, prev_cpu, 0, -weight);
	}
2499

2500 2501
	tg = task_group(p);
	weight = p->se.load.weight;
2502

2503 2504
	/*
	 * In low-load situations, where prev_cpu is idle and this_cpu is idle
2505 2506 2507
	 * 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.
2508 2509 2510 2511
	 *
	 * Otherwise check if either cpus are near enough in load to allow this
	 * task to be woken on this_cpu.
	 */
2512 2513
	if (this_load > 0) {
		s64 this_eff_load, prev_eff_load;
2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526

		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;
2527

2528
	/*
I
Ingo Molnar 已提交
2529 2530 2531
	 * If the currently running task will sleep within
	 * a reasonable amount of time then attract this newly
	 * woken task:
2532
	 */
2533 2534
	if (sync && balanced)
		return 1;
2535

2536
	schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
2537 2538
	tl_per_task = cpu_avg_load_per_task(this_cpu);

2539 2540 2541
	if (balanced ||
	    (this_load <= load &&
	     this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
2542 2543 2544 2545 2546
		/*
		 * This domain has SD_WAKE_AFFINE and
		 * p is cache cold in this domain, and
		 * there is no bad imbalance.
		 */
2547
		schedstat_inc(sd, ttwu_move_affine);
2548
		schedstat_inc(p, se.statistics.nr_wakeups_affine);
2549 2550 2551 2552 2553 2554

		return 1;
	}
	return 0;
}

2555 2556 2557 2558 2559
/*
 * find_idlest_group finds and returns the least busy CPU group within the
 * domain.
 */
static struct sched_group *
P
Peter Zijlstra 已提交
2560
find_idlest_group(struct sched_domain *sd, struct task_struct *p,
2561
		  int this_cpu, int load_idx)
2562
{
2563
	struct sched_group *idlest = NULL, *group = sd->groups;
2564 2565
	unsigned long min_load = ULONG_MAX, this_load = 0;
	int imbalance = 100 + (sd->imbalance_pct-100)/2;
2566

2567 2568 2569 2570
	do {
		unsigned long load, avg_load;
		int local_group;
		int i;
2571

2572 2573
		/* Skip over this group if it has no CPUs allowed */
		if (!cpumask_intersects(sched_group_cpus(group),
2574
					tsk_cpus_allowed(p)))
2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593
			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 */
2594
		avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power;
2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619

		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 */
2620
	for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) {
2621 2622 2623 2624 2625
		load = weighted_cpuload(i);

		if (load < min_load || (load == min_load && i == this_cpu)) {
			min_load = load;
			idlest = i;
2626 2627 2628
		}
	}

2629 2630
	return idlest;
}
2631

2632 2633 2634
/*
 * Try and locate an idle CPU in the sched_domain.
 */
2635
static int select_idle_sibling(struct task_struct *p, int target)
2636 2637 2638
{
	int cpu = smp_processor_id();
	int prev_cpu = task_cpu(p);
2639
	struct sched_domain *sd;
2640 2641
	struct sched_group *sg;
	int i;
2642 2643

	/*
2644 2645
	 * If the task is going to be woken-up on this cpu and if it is
	 * already idle, then it is the right target.
2646
	 */
2647 2648 2649 2650 2651 2652 2653 2654
	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))
2655
		return prev_cpu;
2656 2657

	/*
2658
	 * Otherwise, iterate the domains and find an elegible idle cpu.
2659
	 */
2660
	sd = rcu_dereference(per_cpu(sd_llc, target));
2661
	for_each_lower_domain(sd) {
2662 2663 2664 2665 2666 2667 2668 2669 2670 2671
		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;
			}
2672

2673 2674 2675 2676 2677 2678 2679 2680
			target = cpumask_first_and(sched_group_cpus(sg),
					tsk_cpus_allowed(p));
			goto done;
next:
			sg = sg->next;
		} while (sg != sd->groups);
	}
done:
2681 2682 2683
	return target;
}

2684 2685 2686 2687 2688 2689 2690 2691 2692 2693 2694
/*
 * 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.
 */
2695
static int
2696
select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
2697
{
2698
	struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
2699 2700 2701
	int cpu = smp_processor_id();
	int prev_cpu = task_cpu(p);
	int new_cpu = cpu;
2702
	int want_affine = 0;
2703
	int sync = wake_flags & WF_SYNC;
2704

2705
	if (p->nr_cpus_allowed == 1)
2706 2707
		return prev_cpu;

2708
	if (sd_flag & SD_BALANCE_WAKE) {
2709
		if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
2710 2711 2712
			want_affine = 1;
		new_cpu = prev_cpu;
	}
2713

2714
	rcu_read_lock();
2715
	for_each_domain(cpu, tmp) {
2716 2717 2718
		if (!(tmp->flags & SD_LOAD_BALANCE))
			continue;

2719
		/*
2720 2721
		 * If both cpu and prev_cpu are part of this domain,
		 * cpu is a valid SD_WAKE_AFFINE target.
2722
		 */
2723 2724 2725
		if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
		    cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
			affine_sd = tmp;
2726
			break;
2727
		}
2728

2729
		if (tmp->flags & sd_flag)
2730 2731 2732
			sd = tmp;
	}

2733
	if (affine_sd) {
2734
		if (cpu != prev_cpu && wake_affine(affine_sd, p, sync))
2735 2736 2737 2738
			prev_cpu = cpu;

		new_cpu = select_idle_sibling(p, prev_cpu);
		goto unlock;
2739
	}
2740

2741
	while (sd) {
2742
		int load_idx = sd->forkexec_idx;
2743
		struct sched_group *group;
2744
		int weight;
2745

2746
		if (!(sd->flags & sd_flag)) {
2747 2748 2749
			sd = sd->child;
			continue;
		}
2750

2751 2752
		if (sd_flag & SD_BALANCE_WAKE)
			load_idx = sd->wake_idx;
2753

2754
		group = find_idlest_group(sd, p, cpu, load_idx);
2755 2756 2757 2758
		if (!group) {
			sd = sd->child;
			continue;
		}
I
Ingo Molnar 已提交
2759

2760
		new_cpu = find_idlest_cpu(group, p, cpu);
2761 2762 2763 2764
		if (new_cpu == -1 || new_cpu == cpu) {
			/* Now try balancing at a lower domain level of cpu */
			sd = sd->child;
			continue;
2765
		}
2766 2767 2768

		/* Now try balancing at a lower domain level of new_cpu */
		cpu = new_cpu;
2769
		weight = sd->span_weight;
2770 2771
		sd = NULL;
		for_each_domain(cpu, tmp) {
2772
			if (weight <= tmp->span_weight)
2773
				break;
2774
			if (tmp->flags & sd_flag)
2775 2776 2777
				sd = tmp;
		}
		/* while loop will break here if sd == NULL */
2778
	}
2779 2780
unlock:
	rcu_read_unlock();
2781

2782
	return new_cpu;
2783 2784 2785
}
#endif /* CONFIG_SMP */

P
Peter Zijlstra 已提交
2786 2787
static unsigned long
wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
2788 2789 2790 2791
{
	unsigned long gran = sysctl_sched_wakeup_granularity;

	/*
P
Peter Zijlstra 已提交
2792 2793
	 * Since its curr running now, convert the gran from real-time
	 * to virtual-time in his units.
M
Mike Galbraith 已提交
2794 2795 2796 2797 2798 2799 2800 2801 2802
	 *
	 * 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.
2803
	 */
2804
	return calc_delta_fair(gran, se);
2805 2806
}

2807 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828
/*
 * 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;

P
Peter Zijlstra 已提交
2829
	gran = wakeup_gran(curr, se);
2830 2831 2832 2833 2834 2835
	if (vdiff > gran)
		return 1;

	return 0;
}

2836 2837
static void set_last_buddy(struct sched_entity *se)
{
2838 2839 2840 2841 2842
	if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
		return;

	for_each_sched_entity(se)
		cfs_rq_of(se)->last = se;
2843 2844 2845 2846
}

static void set_next_buddy(struct sched_entity *se)
{
2847 2848 2849 2850 2851
	if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
		return;

	for_each_sched_entity(se)
		cfs_rq_of(se)->next = se;
2852 2853
}

2854 2855
static void set_skip_buddy(struct sched_entity *se)
{
2856 2857
	for_each_sched_entity(se)
		cfs_rq_of(se)->skip = se;
2858 2859
}

2860 2861 2862
/*
 * Preempt the current task with a newly woken task if needed:
 */
2863
static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
2864 2865
{
	struct task_struct *curr = rq->curr;
2866
	struct sched_entity *se = &curr->se, *pse = &p->se;
2867
	struct cfs_rq *cfs_rq = task_cfs_rq(curr);
2868
	int scale = cfs_rq->nr_running >= sched_nr_latency;
2869
	int next_buddy_marked = 0;
2870

I
Ingo Molnar 已提交
2871 2872 2873
	if (unlikely(se == pse))
		return;

2874
	/*
2875
	 * This is possible from callers such as move_task(), in which we
2876 2877 2878 2879 2880 2881 2882
	 * 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;

2883
	if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
M
Mike Galbraith 已提交
2884
		set_next_buddy(pse);
2885 2886
		next_buddy_marked = 1;
	}
P
Peter Zijlstra 已提交
2887

2888 2889 2890
	/*
	 * We can come here with TIF_NEED_RESCHED already set from new task
	 * wake up path.
2891 2892 2893 2894 2895 2896
	 *
	 * 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.
2897 2898 2899 2900
	 */
	if (test_tsk_need_resched(curr))
		return;

2901 2902 2903 2904 2905
	/* Idle tasks are by definition preempted by non-idle tasks. */
	if (unlikely(curr->policy == SCHED_IDLE) &&
	    likely(p->policy != SCHED_IDLE))
		goto preempt;

2906
	/*
2907 2908
	 * Batch and idle tasks do not preempt non-idle tasks (their preemption
	 * is driven by the tick):
2909
	 */
2910
	if (unlikely(p->policy != SCHED_NORMAL))
2911
		return;
2912

2913
	find_matching_se(&se, &pse);
2914
	update_curr(cfs_rq_of(se));
2915
	BUG_ON(!pse);
2916 2917 2918 2919 2920 2921 2922
	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);
2923
		goto preempt;
2924
	}
2925

2926
	return;
2927

2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943
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);
2944 2945
}

2946
static struct task_struct *pick_next_task_fair(struct rq *rq)
2947
{
P
Peter Zijlstra 已提交
2948
	struct task_struct *p;
2949 2950 2951
	struct cfs_rq *cfs_rq = &rq->cfs;
	struct sched_entity *se;

2952
	if (!cfs_rq->nr_running)
2953 2954 2955
		return NULL;

	do {
2956
		se = pick_next_entity(cfs_rq);
2957
		set_next_entity(cfs_rq, se);
2958 2959 2960
		cfs_rq = group_cfs_rq(se);
	} while (cfs_rq);

P
Peter Zijlstra 已提交
2961
	p = task_of(se);
2962 2963
	if (hrtick_enabled(rq))
		hrtick_start_fair(rq, p);
P
Peter Zijlstra 已提交
2964 2965

	return p;
2966 2967 2968 2969 2970
}

/*
 * Account for a descheduled task:
 */
2971
static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
2972 2973 2974 2975 2976 2977
{
	struct sched_entity *se = &prev->se;
	struct cfs_rq *cfs_rq;

	for_each_sched_entity(se) {
		cfs_rq = cfs_rq_of(se);
2978
		put_prev_entity(cfs_rq, se);
2979 2980 2981
	}
}

2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006
/*
 * 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);
3007 3008 3009 3010 3011 3012
		/*
		 * Tell update_rq_clock() that we've just updated,
		 * so we don't do microscopic update in schedule()
		 * and double the fastpath cost.
		 */
		 rq->skip_clock_update = 1;
3013 3014 3015 3016 3017
	}

	set_skip_buddy(se);
}

3018 3019 3020 3021
static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt)
{
	struct sched_entity *se = &p->se;

3022 3023
	/* throttled hierarchies are not runnable */
	if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
3024 3025 3026 3027 3028 3029 3030 3031 3032 3033
		return false;

	/* Tell the scheduler that we'd really like pse to run next. */
	set_next_buddy(se);

	yield_task_fair(rq);

	return true;
}

3034
#ifdef CONFIG_SMP
3035 3036 3037 3038
/**************************************************
 * Fair scheduling class load-balancing methods:
 */

3039 3040
static unsigned long __read_mostly max_load_balance_interval = HZ/10;

3041
#define LBF_ALL_PINNED	0x01
3042
#define LBF_NEED_BREAK	0x02
3043
#define LBF_SOME_PINNED 0x04
3044 3045 3046 3047 3048

struct lb_env {
	struct sched_domain	*sd;

	struct rq		*src_rq;
3049
	int			src_cpu;
3050 3051 3052 3053

	int			dst_cpu;
	struct rq		*dst_rq;

3054 3055
	struct cpumask		*dst_grpmask;
	int			new_dst_cpu;
3056
	enum cpu_idle_type	idle;
3057
	long			imbalance;
3058 3059 3060
	/* The set of CPUs under consideration for load-balancing */
	struct cpumask		*cpus;

3061
	unsigned int		flags;
3062 3063 3064 3065

	unsigned int		loop;
	unsigned int		loop_break;
	unsigned int		loop_max;
3066 3067
};

3068
/*
3069
 * move_task - move a task from one runqueue to another runqueue.
3070 3071
 * Both runqueues must be locked.
 */
3072
static void move_task(struct task_struct *p, struct lb_env *env)
3073
{
3074 3075 3076 3077
	deactivate_task(env->src_rq, p, 0);
	set_task_cpu(p, env->dst_cpu);
	activate_task(env->dst_rq, p, 0);
	check_preempt_curr(env->dst_rq, p, 0);
3078 3079
}

3080 3081 3082 3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109 3110 3111
/*
 * 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;
}

3112 3113 3114 3115
/*
 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
 */
static
3116
int can_migrate_task(struct task_struct *p, struct lb_env *env)
3117 3118 3119 3120 3121 3122 3123 3124
{
	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.
	 */
3125
	if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
3126 3127
		int new_dst_cpu;

3128
		schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
3129 3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140 3141 3142 3143 3144 3145 3146

		/*
		 * Remember if this task can be migrated to any other cpu in
		 * our sched_group. We may want to revisit it if we couldn't
		 * meet load balance goals by pulling other tasks on src_cpu.
		 *
		 * Also avoid computing new_dst_cpu if we have already computed
		 * one in current iteration.
		 */
		if (!env->dst_grpmask || (env->flags & LBF_SOME_PINNED))
			return 0;

		new_dst_cpu = cpumask_first_and(env->dst_grpmask,
						tsk_cpus_allowed(p));
		if (new_dst_cpu < nr_cpu_ids) {
			env->flags |= LBF_SOME_PINNED;
			env->new_dst_cpu = new_dst_cpu;
		}
3147 3148
		return 0;
	}
3149 3150

	/* Record that we found atleast one task that could run on dst_cpu */
3151
	env->flags &= ~LBF_ALL_PINNED;
3152

3153
	if (task_running(env->src_rq, p)) {
3154
		schedstat_inc(p, se.statistics.nr_failed_migrations_running);
3155 3156 3157 3158 3159 3160 3161 3162 3163
		return 0;
	}

	/*
	 * Aggressive migration if:
	 * 1) task is cache cold, or
	 * 2) too many balance attempts have failed.
	 */

3164
	tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
3165
	if (!tsk_cache_hot ||
3166
		env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
3167 3168
#ifdef CONFIG_SCHEDSTATS
		if (tsk_cache_hot) {
3169
			schedstat_inc(env->sd, lb_hot_gained[env->idle]);
3170
			schedstat_inc(p, se.statistics.nr_forced_migrations);
3171 3172 3173 3174 3175 3176
		}
#endif
		return 1;
	}

	if (tsk_cache_hot) {
3177
		schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
3178 3179 3180 3181 3182
		return 0;
	}
	return 1;
}

3183 3184 3185 3186 3187 3188 3189
/*
 * 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.
 */
3190
static int move_one_task(struct lb_env *env)
3191 3192 3193
{
	struct task_struct *p, *n;

3194 3195 3196
	list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
		if (throttled_lb_pair(task_group(p), env->src_rq->cpu, env->dst_cpu))
			continue;
3197

3198 3199
		if (!can_migrate_task(p, env))
			continue;
3200

3201 3202 3203 3204 3205 3206 3207 3208
		move_task(p, env);
		/*
		 * Right now, this is only the second place move_task()
		 * is called, so we can safely collect move_task()
		 * stats here rather than inside move_task().
		 */
		schedstat_inc(env->sd, lb_gained[env->idle]);
		return 1;
3209 3210 3211 3212
	}
	return 0;
}

3213 3214
static unsigned long task_h_load(struct task_struct *p);

3215 3216
static const unsigned int sched_nr_migrate_break = 32;

3217
/*
3218
 * move_tasks tries to move up to imbalance weighted load from busiest to
3219 3220 3221 3222 3223 3224
 * 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 lb_env *env)
3225
{
3226 3227
	struct list_head *tasks = &env->src_rq->cfs_tasks;
	struct task_struct *p;
3228 3229
	unsigned long load;
	int pulled = 0;
3230

3231
	if (env->imbalance <= 0)
3232
		return 0;
3233

3234 3235
	while (!list_empty(tasks)) {
		p = list_first_entry(tasks, struct task_struct, se.group_node);
3236

3237 3238
		env->loop++;
		/* We've more or less seen every task there is, call it quits */
3239
		if (env->loop > env->loop_max)
3240
			break;
3241 3242

		/* take a breather every nr_migrate tasks */
3243
		if (env->loop > env->loop_break) {
3244
			env->loop_break += sched_nr_migrate_break;
3245
			env->flags |= LBF_NEED_BREAK;
3246
			break;
3247
		}
3248

3249
		if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
3250 3251 3252
			goto next;

		load = task_h_load(p);
3253

3254
		if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed)
3255 3256
			goto next;

3257
		if ((load / 2) > env->imbalance)
3258
			goto next;
3259

3260 3261
		if (!can_migrate_task(p, env))
			goto next;
3262

3263
		move_task(p, env);
3264
		pulled++;
3265
		env->imbalance -= load;
3266 3267

#ifdef CONFIG_PREEMPT
3268 3269 3270 3271 3272
		/*
		 * NEWIDLE balancing is a source of latency, so preemptible
		 * kernels will stop after the first task is pulled to minimize
		 * the critical section.
		 */
3273
		if (env->idle == CPU_NEWLY_IDLE)
3274
			break;
3275 3276
#endif

3277 3278 3279 3280
		/*
		 * We only want to steal up to the prescribed amount of
		 * weighted load.
		 */
3281
		if (env->imbalance <= 0)
3282
			break;
3283 3284 3285

		continue;
next:
3286
		list_move_tail(&p->se.group_node, tasks);
3287
	}
3288

3289
	/*
3290 3291 3292
	 * Right now, this is one of only two places move_task() is called,
	 * so we can safely collect move_task() stats here rather than
	 * inside move_task().
3293
	 */
3294
	schedstat_add(env->sd, lb_gained[env->idle], pulled);
3295

3296
	return pulled;
3297 3298
}

P
Peter Zijlstra 已提交
3299
#ifdef CONFIG_FAIR_GROUP_SCHED
3300 3301 3302
/*
 * update tg->load_weight by folding this cpu's load_avg
 */
3303
static int update_shares_cpu(struct task_group *tg, int cpu)
3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317
{
	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);
3318
	update_cfs_load(cfs_rq, 1);
3319 3320 3321 3322 3323

	/*
	 * We need to update shares after updating tg->load_weight in
	 * order to adjust the weight of groups with long running tasks.
	 */
3324
	update_cfs_shares(cfs_rq);
3325 3326 3327 3328 3329 3330 3331 3332 3333 3334 3335 3336

	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();
3337 3338 3339 3340
	/*
	 * Iterates the task_group tree in a bottom up fashion, see
	 * list_add_leaf_cfs_rq() for details.
	 */
3341 3342 3343 3344 3345
	for_each_leaf_cfs_rq(rq, cfs_rq) {
		/* throttled entities do not contribute to load */
		if (throttled_hierarchy(cfs_rq))
			continue;

3346
		update_shares_cpu(cfs_rq->tg, cpu);
3347
	}
3348 3349 3350
	rcu_read_unlock();
}

3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375
/*
 * 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)
{
3376 3377 3378 3379 3380 3381 3382 3383
	struct rq *rq = cpu_rq(cpu);
	unsigned long now = jiffies;

	if (rq->h_load_throttle == now)
		return;

	rq->h_load_throttle = now;

3384
	rcu_read_lock();
3385
	walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
3386
	rcu_read_unlock();
3387 3388
}

3389
static unsigned long task_h_load(struct task_struct *p)
P
Peter Zijlstra 已提交
3390
{
3391 3392
	struct cfs_rq *cfs_rq = task_cfs_rq(p);
	unsigned long load;
P
Peter Zijlstra 已提交
3393

3394 3395
	load = p->se.load.weight;
	load = div_u64(load * cfs_rq->h_load, cfs_rq->load.weight + 1);
P
Peter Zijlstra 已提交
3396

3397
	return load;
P
Peter Zijlstra 已提交
3398 3399
}
#else
3400 3401 3402 3403
static inline void update_shares(int cpu)
{
}

3404
static inline void update_h_load(long cpu)
P
Peter Zijlstra 已提交
3405 3406 3407
{
}

3408
static unsigned long task_h_load(struct task_struct *p)
3409
{
3410
	return p->se.load.weight;
3411
}
P
Peter Zijlstra 已提交
3412
#endif
3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424 3425 3426 3427 3428 3429

/********** 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;
3430
	unsigned long this_has_capacity;
3431
	unsigned int  this_idle_cpus;
3432 3433

	/* Statistics of the busiest group */
3434
	unsigned int  busiest_idle_cpus;
3435 3436 3437
	unsigned long max_load;
	unsigned long busiest_load_per_task;
	unsigned long busiest_nr_running;
3438
	unsigned long busiest_group_capacity;
3439
	unsigned long busiest_has_capacity;
3440
	unsigned int  busiest_group_weight;
3441 3442 3443 3444 3445 3446 3447 3448 3449 3450 3451 3452 3453

	int group_imb; /* Is there imbalance in this sd */
};

/*
 * 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;
3454 3455
	unsigned long idle_cpus;
	unsigned long group_weight;
3456
	int group_imb; /* Is there an imbalance in the group ? */
3457
	int group_has_capacity; /* Is there extra capacity in the group? */
3458 3459 3460 3461 3462 3463 3464 3465 3466 3467 3468 3469 3470 3471 3472 3473 3474 3475 3476 3477 3478 3479 3480 3481 3482 3483 3484 3485 3486 3487
};

/**
 * 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;
}

unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
{
3488
	return SCHED_POWER_SCALE;
3489 3490 3491 3492 3493 3494 3495 3496 3497
}

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)
{
3498
	unsigned long weight = sd->span_weight;
3499 3500 3501 3502 3503 3504 3505 3506 3507 3508 3509 3510 3511 3512 3513
	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);
3514
	u64 total, available, age_stamp, avg;
3515

3516 3517 3518 3519 3520 3521 3522 3523
	/*
	 * Since we're reading these variables without serialization make sure
	 * we read them once before doing sanity checks on them.
	 */
	age_stamp = ACCESS_ONCE(rq->age_stamp);
	avg = ACCESS_ONCE(rq->rt_avg);

	total = sched_avg_period() + (rq->clock - age_stamp);
3524

3525
	if (unlikely(total < avg)) {
3526 3527 3528
		/* Ensures that power won't end up being negative */
		available = 0;
	} else {
3529
		available = total - avg;
3530
	}
3531

3532 3533
	if (unlikely((s64)total < SCHED_POWER_SCALE))
		total = SCHED_POWER_SCALE;
3534

3535
	total >>= SCHED_POWER_SHIFT;
3536 3537 3538 3539 3540 3541

	return div_u64(available, total);
}

static void update_cpu_power(struct sched_domain *sd, int cpu)
{
3542
	unsigned long weight = sd->span_weight;
3543
	unsigned long power = SCHED_POWER_SCALE;
3544 3545 3546 3547 3548 3549 3550 3551
	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);

3552
		power >>= SCHED_POWER_SHIFT;
3553 3554
	}

3555
	sdg->sgp->power_orig = power;
3556 3557 3558 3559 3560 3561

	if (sched_feat(ARCH_POWER))
		power *= arch_scale_freq_power(sd, cpu);
	else
		power *= default_scale_freq_power(sd, cpu);

3562
	power >>= SCHED_POWER_SHIFT;
3563

3564
	power *= scale_rt_power(cpu);
3565
	power >>= SCHED_POWER_SHIFT;
3566 3567 3568 3569

	if (!power)
		power = 1;

3570
	cpu_rq(cpu)->cpu_power = power;
3571
	sdg->sgp->power = power;
3572 3573
}

3574
void update_group_power(struct sched_domain *sd, int cpu)
3575 3576 3577 3578
{
	struct sched_domain *child = sd->child;
	struct sched_group *group, *sdg = sd->groups;
	unsigned long power;
3579 3580 3581 3582 3583
	unsigned long interval;

	interval = msecs_to_jiffies(sd->balance_interval);
	interval = clamp(interval, 1UL, max_load_balance_interval);
	sdg->sgp->next_update = jiffies + interval;
3584 3585 3586 3587 3588 3589 3590 3591

	if (!child) {
		update_cpu_power(sd, cpu);
		return;
	}

	power = 0;

P
Peter Zijlstra 已提交
3592 3593 3594 3595 3596 3597 3598 3599 3600 3601 3602 3603 3604 3605 3606 3607 3608 3609 3610 3611
	if (child->flags & SD_OVERLAP) {
		/*
		 * SD_OVERLAP domains cannot assume that child groups
		 * span the current group.
		 */

		for_each_cpu(cpu, sched_group_cpus(sdg))
			power += power_of(cpu);
	} else  {
		/*
		 * !SD_OVERLAP domains can assume that child groups
		 * span the current group.
		 */ 

		group = child->groups;
		do {
			power += group->sgp->power;
			group = group->next;
		} while (group != child->groups);
	}
3612

3613
	sdg->sgp->power_orig = sdg->sgp->power = power;
3614 3615
}

3616 3617 3618 3619 3620 3621 3622 3623 3624 3625 3626
/*
 * 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)
{
	/*
3627
	 * Only siblings can have significantly less than SCHED_POWER_SCALE
3628
	 */
P
Peter Zijlstra 已提交
3629
	if (!(sd->flags & SD_SHARE_CPUPOWER))
3630 3631 3632 3633 3634
		return 0;

	/*
	 * If ~90% of the cpu_power is still there, we're good.
	 */
3635
	if (group->sgp->power * 32 > group->sgp->power_orig * 29)
3636 3637 3638 3639 3640
		return 1;

	return 0;
}

3641 3642
/**
 * update_sg_lb_stats - Update sched_group's statistics for load balancing.
3643
 * @env: The load balancing environment.
3644 3645 3646 3647 3648 3649
 * @group: sched_group whose statistics are to be updated.
 * @load_idx: Load index of sched_domain of this_cpu for load calc.
 * @local_group: Does group contain this_cpu.
 * @balance: Should we balance.
 * @sgs: variable to hold the statistics for this group.
 */
3650 3651
static inline void update_sg_lb_stats(struct lb_env *env,
			struct sched_group *group, int load_idx,
3652
			int local_group, int *balance, struct sg_lb_stats *sgs)
3653
{
3654 3655
	unsigned long nr_running, max_nr_running, min_nr_running;
	unsigned long load, max_cpu_load, min_cpu_load;
3656
	unsigned int balance_cpu = -1, first_idle_cpu = 0;
3657
	unsigned long avg_load_per_task = 0;
3658
	int i;
3659

3660
	if (local_group)
P
Peter Zijlstra 已提交
3661
		balance_cpu = group_balance_cpu(group);
3662 3663 3664 3665

	/* Tally up the load of all CPUs in the group */
	max_cpu_load = 0;
	min_cpu_load = ~0UL;
3666
	max_nr_running = 0;
3667
	min_nr_running = ~0UL;
3668

3669
	for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
3670 3671
		struct rq *rq = cpu_rq(i);

3672 3673
		nr_running = rq->nr_running;

3674 3675
		/* Bias balancing toward cpus of our domain */
		if (local_group) {
P
Peter Zijlstra 已提交
3676 3677
			if (idle_cpu(i) && !first_idle_cpu &&
					cpumask_test_cpu(i, sched_group_mask(group))) {
3678
				first_idle_cpu = 1;
3679 3680
				balance_cpu = i;
			}
3681 3682

			load = target_load(i, load_idx);
3683 3684
		} else {
			load = source_load(i, load_idx);
3685
			if (load > max_cpu_load)
3686 3687 3688
				max_cpu_load = load;
			if (min_cpu_load > load)
				min_cpu_load = load;
3689 3690 3691 3692 3693

			if (nr_running > max_nr_running)
				max_nr_running = nr_running;
			if (min_nr_running > nr_running)
				min_nr_running = nr_running;
3694 3695 3696
		}

		sgs->group_load += load;
3697
		sgs->sum_nr_running += nr_running;
3698
		sgs->sum_weighted_load += weighted_cpuload(i);
3699 3700
		if (idle_cpu(i))
			sgs->idle_cpus++;
3701 3702 3703 3704 3705 3706 3707 3708
	}

	/*
	 * 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.
	 */
3709
	if (local_group) {
3710
		if (env->idle != CPU_NEWLY_IDLE) {
3711
			if (balance_cpu != env->dst_cpu) {
3712 3713 3714
				*balance = 0;
				return;
			}
3715
			update_group_power(env->sd, env->dst_cpu);
3716
		} else if (time_after_eq(jiffies, group->sgp->next_update))
3717
			update_group_power(env->sd, env->dst_cpu);
3718 3719 3720
	}

	/* Adjust by relative CPU power of the group */
3721
	sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;
3722 3723 3724

	/*
	 * Consider the group unbalanced when the imbalance is larger
P
Peter Zijlstra 已提交
3725
	 * than the average weight of a task.
3726 3727 3728 3729 3730 3731
	 *
	 * 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?
	 */
3732 3733
	if (sgs->sum_nr_running)
		avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
3734

3735 3736
	if ((max_cpu_load - min_cpu_load) >= avg_load_per_task &&
	    (max_nr_running - min_nr_running) > 1)
3737 3738
		sgs->group_imb = 1;

3739
	sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
3740
						SCHED_POWER_SCALE);
3741
	if (!sgs->group_capacity)
3742
		sgs->group_capacity = fix_small_capacity(env->sd, group);
3743
	sgs->group_weight = group->group_weight;
3744 3745 3746

	if (sgs->group_capacity > sgs->sum_nr_running)
		sgs->group_has_capacity = 1;
3747 3748
}

3749 3750
/**
 * update_sd_pick_busiest - return 1 on busiest group
3751
 * @env: The load balancing environment.
3752 3753
 * @sds: sched_domain statistics
 * @sg: sched_group candidate to be checked for being the busiest
3754
 * @sgs: sched_group statistics
3755 3756 3757 3758
 *
 * Determine if @sg is a busier group than the previously selected
 * busiest group.
 */
3759
static bool update_sd_pick_busiest(struct lb_env *env,
3760 3761
				   struct sd_lb_stats *sds,
				   struct sched_group *sg,
3762
				   struct sg_lb_stats *sgs)
3763 3764 3765 3766 3767 3768 3769 3770 3771 3772 3773 3774 3775 3776 3777
{
	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.
	 */
3778 3779
	if ((env->sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running &&
	    env->dst_cpu < group_first_cpu(sg)) {
3780 3781 3782 3783 3784 3785 3786 3787 3788 3789
		if (!sds->busiest)
			return true;

		if (group_first_cpu(sds->busiest) > group_first_cpu(sg))
			return true;
	}

	return false;
}

3790
/**
3791
 * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
3792
 * @env: The load balancing environment.
3793 3794 3795
 * @balance: Should we balance.
 * @sds: variable to hold the statistics for this sched_domain.
 */
3796
static inline void update_sd_lb_stats(struct lb_env *env,
3797
					int *balance, struct sd_lb_stats *sds)
3798
{
3799 3800
	struct sched_domain *child = env->sd->child;
	struct sched_group *sg = env->sd->groups;
3801 3802 3803 3804 3805 3806
	struct sg_lb_stats sgs;
	int load_idx, prefer_sibling = 0;

	if (child && child->flags & SD_PREFER_SIBLING)
		prefer_sibling = 1;

3807
	load_idx = get_sd_load_idx(env->sd, env->idle);
3808 3809 3810 3811

	do {
		int local_group;

3812
		local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg));
3813
		memset(&sgs, 0, sizeof(sgs));
3814
		update_sg_lb_stats(env, sg, load_idx, local_group, balance, &sgs);
3815

P
Peter Zijlstra 已提交
3816
		if (local_group && !(*balance))
3817 3818 3819
			return;

		sds->total_load += sgs.group_load;
3820
		sds->total_pwr += sg->sgp->power;
3821 3822 3823

		/*
		 * In case the child domain prefers tasks go to siblings
3824
		 * first, lower the sg capacity to one so that we'll try
3825 3826 3827 3828 3829 3830
		 * 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).
3831
		 */
3832
		if (prefer_sibling && !local_group && sds->this_has_capacity)
3833 3834 3835 3836
			sgs.group_capacity = min(sgs.group_capacity, 1UL);

		if (local_group) {
			sds->this_load = sgs.avg_load;
3837
			sds->this = sg;
3838 3839
			sds->this_nr_running = sgs.sum_nr_running;
			sds->this_load_per_task = sgs.sum_weighted_load;
3840
			sds->this_has_capacity = sgs.group_has_capacity;
3841
			sds->this_idle_cpus = sgs.idle_cpus;
3842
		} else if (update_sd_pick_busiest(env, sds, sg, &sgs)) {
3843
			sds->max_load = sgs.avg_load;
3844
			sds->busiest = sg;
3845
			sds->busiest_nr_running = sgs.sum_nr_running;
3846
			sds->busiest_idle_cpus = sgs.idle_cpus;
3847
			sds->busiest_group_capacity = sgs.group_capacity;
3848
			sds->busiest_load_per_task = sgs.sum_weighted_load;
3849
			sds->busiest_has_capacity = sgs.group_has_capacity;
3850
			sds->busiest_group_weight = sgs.group_weight;
3851 3852 3853
			sds->group_imb = sgs.group_imb;
		}

3854
		sg = sg->next;
3855
	} while (sg != env->sd->groups);
3856 3857 3858 3859 3860 3861 3862 3863 3864 3865 3866 3867 3868 3869 3870 3871 3872 3873 3874
}

/**
 * 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.
 *
3875 3876 3877
 * Returns 1 when packing is required and a task should be moved to
 * this CPU.  The amount of the imbalance is returned in *imbalance.
 *
3878
 * @env: The load balancing environment.
3879 3880
 * @sds: Statistics of the sched_domain which is to be packed
 */
3881
static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
3882 3883 3884
{
	int busiest_cpu;

3885
	if (!(env->sd->flags & SD_ASYM_PACKING))
3886 3887 3888 3889 3890 3891
		return 0;

	if (!sds->busiest)
		return 0;

	busiest_cpu = group_first_cpu(sds->busiest);
3892
	if (env->dst_cpu > busiest_cpu)
3893 3894
		return 0;

3895 3896 3897
	env->imbalance = DIV_ROUND_CLOSEST(
		sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE);

3898
	return 1;
3899 3900 3901 3902 3903 3904
}

/**
 * fix_small_imbalance - Calculate the minor imbalance that exists
 *			amongst the groups of a sched_domain, during
 *			load balancing.
3905
 * @env: The load balancing environment.
3906 3907
 * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
 */
3908 3909
static inline
void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
3910 3911 3912
{
	unsigned long tmp, pwr_now = 0, pwr_move = 0;
	unsigned int imbn = 2;
3913
	unsigned long scaled_busy_load_per_task;
3914 3915 3916 3917 3918 3919

	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;
3920
	} else {
3921
		sds->this_load_per_task =
3922 3923
			cpu_avg_load_per_task(env->dst_cpu);
	}
3924

3925
	scaled_busy_load_per_task = sds->busiest_load_per_task
3926
					 * SCHED_POWER_SCALE;
3927
	scaled_busy_load_per_task /= sds->busiest->sgp->power;
3928 3929 3930

	if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
			(scaled_busy_load_per_task * imbn)) {
3931
		env->imbalance = sds->busiest_load_per_task;
3932 3933 3934 3935 3936 3937 3938 3939 3940
		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.
	 */

3941
	pwr_now += sds->busiest->sgp->power *
3942
			min(sds->busiest_load_per_task, sds->max_load);
3943
	pwr_now += sds->this->sgp->power *
3944
			min(sds->this_load_per_task, sds->this_load);
3945
	pwr_now /= SCHED_POWER_SCALE;
3946 3947

	/* Amount of load we'd subtract */
3948
	tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
3949
		sds->busiest->sgp->power;
3950
	if (sds->max_load > tmp)
3951
		pwr_move += sds->busiest->sgp->power *
3952 3953 3954
			min(sds->busiest_load_per_task, sds->max_load - tmp);

	/* Amount of load we'd add */
3955
	if (sds->max_load * sds->busiest->sgp->power <
3956
		sds->busiest_load_per_task * SCHED_POWER_SCALE)
3957 3958
		tmp = (sds->max_load * sds->busiest->sgp->power) /
			sds->this->sgp->power;
3959
	else
3960
		tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
3961 3962
			sds->this->sgp->power;
	pwr_move += sds->this->sgp->power *
3963
			min(sds->this_load_per_task, sds->this_load + tmp);
3964
	pwr_move /= SCHED_POWER_SCALE;
3965 3966 3967

	/* Move if we gain throughput */
	if (pwr_move > pwr_now)
3968
		env->imbalance = sds->busiest_load_per_task;
3969 3970 3971 3972 3973
}

/**
 * calculate_imbalance - Calculate the amount of imbalance present within the
 *			 groups of a given sched_domain during load balance.
3974
 * @env: load balance environment
3975 3976
 * @sds: statistics of the sched_domain whose imbalance is to be calculated.
 */
3977
static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
3978
{
3979 3980 3981 3982 3983 3984 3985 3986
	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);
	}

3987 3988 3989 3990 3991 3992
	/*
	 * 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) {
3993 3994
		env->imbalance = 0;
		return fix_small_imbalance(env, sds);
3995 3996
	}

3997 3998 3999 4000 4001 4002 4003
	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);

4004
		load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
4005

4006
		load_above_capacity /= sds->busiest->sgp->power;
4007 4008 4009 4010 4011 4012 4013 4014 4015 4016 4017 4018 4019
	}

	/*
	 * 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);
4020 4021

	/* How much load to actually move to equalise the imbalance */
4022
	env->imbalance = min(max_pull * sds->busiest->sgp->power,
4023
		(sds->avg_load - sds->this_load) * sds->this->sgp->power)
4024
			/ SCHED_POWER_SCALE;
4025 4026 4027

	/*
	 * if *imbalance is less than the average load per runnable task
L
Lucas De Marchi 已提交
4028
	 * there is no guarantee that any tasks will be moved so we'll have
4029 4030 4031
	 * a think about bumping its value to force at least one task to be
	 * moved
	 */
4032 4033
	if (env->imbalance < sds->busiest_load_per_task)
		return fix_small_imbalance(env, sds);
4034 4035

}
4036

4037 4038 4039 4040 4041 4042 4043 4044 4045 4046 4047 4048
/******* 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.
 *
4049
 * @env: The load balancing environment.
4050 4051 4052 4053 4054 4055 4056 4057 4058
 * @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 *
4059
find_busiest_group(struct lb_env *env, int *balance)
4060 4061 4062 4063 4064 4065 4066 4067 4068
{
	struct sd_lb_stats sds;

	memset(&sds, 0, sizeof(sds));

	/*
	 * Compute the various statistics relavent for load balancing at
	 * this level.
	 */
4069
	update_sd_lb_stats(env, balance, &sds);
4070

4071 4072 4073
	/*
	 * this_cpu is not the appropriate cpu to perform load balancing at
	 * this level.
4074
	 */
P
Peter Zijlstra 已提交
4075
	if (!(*balance))
4076 4077
		goto ret;

4078 4079
	if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) &&
	    check_asym_packing(env, &sds))
4080 4081
		return sds.busiest;

4082
	/* There is no busy sibling group to pull tasks from */
4083 4084 4085
	if (!sds.busiest || sds.busiest_nr_running == 0)
		goto out_balanced;

4086
	sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
4087

P
Peter Zijlstra 已提交
4088 4089 4090 4091 4092 4093 4094 4095
	/*
	 * 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;

4096
	/* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
4097
	if (env->idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
4098 4099 4100
			!sds.busiest_has_capacity)
		goto force_balance;

4101 4102 4103 4104
	/*
	 * If the local group is more busy than the selected busiest group
	 * don't try and pull any tasks.
	 */
4105 4106 4107
	if (sds.this_load >= sds.max_load)
		goto out_balanced;

4108 4109 4110 4111
	/*
	 * Don't pull any tasks if this group is already above the domain
	 * average load.
	 */
4112 4113 4114
	if (sds.this_load >= sds.avg_load)
		goto out_balanced;

4115
	if (env->idle == CPU_IDLE) {
4116 4117 4118 4119 4120 4121
		/*
		 * 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.
		 */
4122
		if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) &&
4123 4124
		    sds.busiest_nr_running <= sds.busiest_group_weight)
			goto out_balanced;
4125 4126 4127 4128 4129
	} else {
		/*
		 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
		 * imbalance_pct to be conservative.
		 */
4130
		if (100 * sds.max_load <= env->sd->imbalance_pct * sds.this_load)
4131
			goto out_balanced;
4132
	}
4133

4134
force_balance:
4135
	/* Looks like there is an imbalance. Compute it */
4136
	calculate_imbalance(env, &sds);
4137 4138 4139 4140
	return sds.busiest;

out_balanced:
ret:
4141
	env->imbalance = 0;
4142 4143 4144 4145 4146 4147
	return NULL;
}

/*
 * find_busiest_queue - find the busiest runqueue among the cpus in group.
 */
4148
static struct rq *find_busiest_queue(struct lb_env *env,
4149
				     struct sched_group *group)
4150 4151 4152 4153 4154 4155 4156
{
	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);
4157 4158
		unsigned long capacity = DIV_ROUND_CLOSEST(power,
							   SCHED_POWER_SCALE);
4159 4160
		unsigned long wl;

4161
		if (!capacity)
4162
			capacity = fix_small_capacity(env->sd, group);
4163

4164
		if (!cpumask_test_cpu(i, env->cpus))
4165 4166 4167
			continue;

		rq = cpu_rq(i);
4168
		wl = weighted_cpuload(i);
4169

4170 4171 4172 4173
		/*
		 * When comparing with imbalance, use weighted_cpuload()
		 * which is not scaled with the cpu power.
		 */
4174
		if (capacity && rq->nr_running == 1 && wl > env->imbalance)
4175 4176
			continue;

4177 4178 4179 4180 4181 4182
		/*
		 * 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.
		 */
4183
		wl = (wl * SCHED_POWER_SCALE) / power;
4184

4185 4186 4187 4188 4189 4190 4191 4192 4193 4194 4195 4196 4197 4198 4199 4200
		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. */
4201
DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
4202

4203
static int need_active_balance(struct lb_env *env)
4204
{
4205 4206 4207
	struct sched_domain *sd = env->sd;

	if (env->idle == CPU_NEWLY_IDLE) {
4208 4209 4210 4211 4212 4213

		/*
		 * ASYM_PACKING needs to force migrate tasks from busy but
		 * higher numbered CPUs in order to pack all tasks in the
		 * lowest numbered CPUs.
		 */
4214
		if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu)
4215
			return 1;
4216 4217 4218 4219 4220
	}

	return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
}

4221 4222
static int active_load_balance_cpu_stop(void *data);

4223 4224 4225 4226 4227 4228 4229 4230
/*
 * 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)
{
4231 4232
	int ld_moved, cur_ld_moved, active_balance = 0;
	int lb_iterations, max_lb_iterations;
4233 4234 4235 4236 4237
	struct sched_group *group;
	struct rq *busiest;
	unsigned long flags;
	struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);

4238 4239
	struct lb_env env = {
		.sd		= sd,
4240 4241
		.dst_cpu	= this_cpu,
		.dst_rq		= this_rq,
4242
		.dst_grpmask    = sched_group_cpus(sd->groups),
4243
		.idle		= idle,
4244
		.loop_break	= sched_nr_migrate_break,
4245
		.cpus		= cpus,
4246 4247
	};

4248
	cpumask_copy(cpus, cpu_active_mask);
4249
	max_lb_iterations = cpumask_weight(env.dst_grpmask);
4250 4251 4252 4253

	schedstat_inc(sd, lb_count[idle]);

redo:
4254
	group = find_busiest_group(&env, balance);
4255 4256 4257 4258 4259 4260 4261 4262 4263

	if (*balance == 0)
		goto out_balanced;

	if (!group) {
		schedstat_inc(sd, lb_nobusyg[idle]);
		goto out_balanced;
	}

4264
	busiest = find_busiest_queue(&env, group);
4265 4266 4267 4268 4269
	if (!busiest) {
		schedstat_inc(sd, lb_nobusyq[idle]);
		goto out_balanced;
	}

4270
	BUG_ON(busiest == env.dst_rq);
4271

4272
	schedstat_add(sd, lb_imbalance[idle], env.imbalance);
4273 4274

	ld_moved = 0;
4275
	lb_iterations = 1;
4276 4277 4278 4279 4280 4281 4282
	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.
		 */
4283
		env.flags |= LBF_ALL_PINNED;
4284 4285 4286
		env.src_cpu   = busiest->cpu;
		env.src_rq    = busiest;
		env.loop_max  = min(sysctl_sched_nr_migrate, busiest->nr_running);
4287

4288
		update_h_load(env.src_cpu);
4289
more_balance:
4290
		local_irq_save(flags);
4291
		double_rq_lock(env.dst_rq, busiest);
4292 4293 4294 4295 4296 4297 4298

		/*
		 * cur_ld_moved - load moved in current iteration
		 * ld_moved     - cumulative load moved across iterations
		 */
		cur_ld_moved = move_tasks(&env);
		ld_moved += cur_ld_moved;
4299
		double_rq_unlock(env.dst_rq, busiest);
4300 4301
		local_irq_restore(flags);

4302 4303 4304 4305 4306
		if (env.flags & LBF_NEED_BREAK) {
			env.flags &= ~LBF_NEED_BREAK;
			goto more_balance;
		}

4307 4308 4309
		/*
		 * some other cpu did the load balance for us.
		 */
4310 4311 4312 4313 4314 4315 4316 4317 4318 4319 4320 4321 4322 4323 4324 4325 4326 4327 4328 4329 4330 4331 4332 4333 4334
		if (cur_ld_moved && env.dst_cpu != smp_processor_id())
			resched_cpu(env.dst_cpu);

		/*
		 * Revisit (affine) tasks on src_cpu that couldn't be moved to
		 * us and move them to an alternate dst_cpu in our sched_group
		 * where they can run. The upper limit on how many times we
		 * iterate on same src_cpu is dependent on number of cpus in our
		 * sched_group.
		 *
		 * This changes load balance semantics a bit on who can move
		 * load to a given_cpu. In addition to the given_cpu itself
		 * (or a ilb_cpu acting on its behalf where given_cpu is
		 * nohz-idle), we now have balance_cpu in a position to move
		 * load to given_cpu. In rare situations, this may cause
		 * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
		 * _independently_ and at _same_ time to move some load to
		 * given_cpu) causing exceess load to be moved to given_cpu.
		 * This however should not happen so much in practice and
		 * moreover subsequent load balance cycles should correct the
		 * excess load moved.
		 */
		if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0 &&
				lb_iterations++ < max_lb_iterations) {

4335
			env.dst_rq	 = cpu_rq(env.new_dst_cpu);
4336 4337 4338 4339 4340 4341 4342 4343 4344 4345
			env.dst_cpu	 = env.new_dst_cpu;
			env.flags	&= ~LBF_SOME_PINNED;
			env.loop	 = 0;
			env.loop_break	 = sched_nr_migrate_break;
			/*
			 * Go back to "more_balance" rather than "redo" since we
			 * need to continue with same src_cpu.
			 */
			goto more_balance;
		}
4346 4347

		/* All tasks on this runqueue were pinned by CPU affinity */
4348
		if (unlikely(env.flags & LBF_ALL_PINNED)) {
4349
			cpumask_clear_cpu(cpu_of(busiest), cpus);
4350 4351 4352
			if (!cpumask_empty(cpus)) {
				env.loop = 0;
				env.loop_break = sched_nr_migrate_break;
4353
				goto redo;
4354
			}
4355 4356 4357 4358 4359 4360
			goto out_balanced;
		}
	}

	if (!ld_moved) {
		schedstat_inc(sd, lb_failed[idle]);
4361 4362 4363 4364 4365 4366 4367 4368
		/*
		 * 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++;
4369

4370
		if (need_active_balance(&env)) {
4371 4372
			raw_spin_lock_irqsave(&busiest->lock, flags);

4373 4374 4375
			/* don't kick the active_load_balance_cpu_stop,
			 * if the curr task on busiest cpu can't be
			 * moved to this_cpu
4376 4377
			 */
			if (!cpumask_test_cpu(this_cpu,
4378
					tsk_cpus_allowed(busiest->curr))) {
4379 4380
				raw_spin_unlock_irqrestore(&busiest->lock,
							    flags);
4381
				env.flags |= LBF_ALL_PINNED;
4382 4383 4384
				goto out_one_pinned;
			}

4385 4386 4387 4388 4389
			/*
			 * ->active_balance synchronizes accesses to
			 * ->active_balance_work.  Once set, it's cleared
			 * only after active load balance is finished.
			 */
4390 4391 4392 4393 4394 4395
			if (!busiest->active_balance) {
				busiest->active_balance = 1;
				busiest->push_cpu = this_cpu;
				active_balance = 1;
			}
			raw_spin_unlock_irqrestore(&busiest->lock, flags);
4396

4397
			if (active_balance) {
4398 4399 4400
				stop_one_cpu_nowait(cpu_of(busiest),
					active_load_balance_cpu_stop, busiest,
					&busiest->active_balance_work);
4401
			}
4402 4403 4404 4405 4406 4407 4408 4409 4410 4411 4412 4413 4414 4415 4416 4417 4418 4419 4420 4421 4422 4423 4424 4425 4426 4427 4428 4429 4430 4431 4432 4433 4434

			/*
			 * 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 */
4435
	if (((env.flags & LBF_ALL_PINNED) &&
4436
			sd->balance_interval < MAX_PINNED_INTERVAL) ||
4437 4438 4439
			(sd->balance_interval < sd->max_interval))
		sd->balance_interval *= 2;

4440
	ld_moved = 0;
4441 4442 4443 4444 4445 4446 4447 4448
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.
 */
4449
void idle_balance(int this_cpu, struct rq *this_rq)
4450 4451 4452 4453 4454 4455 4456 4457 4458 4459
{
	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;

4460 4461 4462 4463 4464
	/*
	 * Drop the rq->lock, but keep IRQ/preempt disabled.
	 */
	raw_spin_unlock(&this_rq->lock);

P
Paul Turner 已提交
4465
	update_shares(this_cpu);
4466
	rcu_read_lock();
4467 4468
	for_each_domain(this_cpu, sd) {
		unsigned long interval;
4469
		int balance = 1;
4470 4471 4472 4473

		if (!(sd->flags & SD_LOAD_BALANCE))
			continue;

4474
		if (sd->flags & SD_BALANCE_NEWIDLE) {
4475
			/* If we've pulled tasks over stop searching: */
4476 4477 4478
			pulled_task = load_balance(this_cpu, this_rq,
						   sd, CPU_NEWLY_IDLE, &balance);
		}
4479 4480 4481 4482

		interval = msecs_to_jiffies(sd->balance_interval);
		if (time_after(next_balance, sd->last_balance + interval))
			next_balance = sd->last_balance + interval;
N
Nikhil Rao 已提交
4483 4484
		if (pulled_task) {
			this_rq->idle_stamp = 0;
4485
			break;
N
Nikhil Rao 已提交
4486
		}
4487
	}
4488
	rcu_read_unlock();
4489 4490 4491

	raw_spin_lock(&this_rq->lock);

4492 4493 4494 4495 4496 4497 4498 4499 4500 4501
	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;
	}
}

/*
4502 4503 4504 4505
 * 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.
4506
 */
4507
static int active_load_balance_cpu_stop(void *data)
4508
{
4509 4510
	struct rq *busiest_rq = data;
	int busiest_cpu = cpu_of(busiest_rq);
4511
	int target_cpu = busiest_rq->push_cpu;
4512
	struct rq *target_rq = cpu_rq(target_cpu);
4513
	struct sched_domain *sd;
4514 4515 4516 4517 4518 4519 4520

	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;
4521 4522 4523

	/* Is there any task to move? */
	if (busiest_rq->nr_running <= 1)
4524
		goto out_unlock;
4525 4526 4527 4528 4529 4530 4531 4532 4533 4534 4535 4536

	/*
	 * 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. */
4537
	rcu_read_lock();
4538 4539 4540 4541 4542 4543 4544
	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)) {
4545 4546
		struct lb_env env = {
			.sd		= sd,
4547 4548 4549 4550
			.dst_cpu	= target_cpu,
			.dst_rq		= target_rq,
			.src_cpu	= busiest_rq->cpu,
			.src_rq		= busiest_rq,
4551 4552 4553
			.idle		= CPU_IDLE,
		};

4554 4555
		schedstat_inc(sd, alb_count);

4556
		if (move_one_task(&env))
4557 4558 4559 4560
			schedstat_inc(sd, alb_pushed);
		else
			schedstat_inc(sd, alb_failed);
	}
4561
	rcu_read_unlock();
4562
	double_unlock_balance(busiest_rq, target_rq);
4563 4564 4565 4566
out_unlock:
	busiest_rq->active_balance = 0;
	raw_spin_unlock_irq(&busiest_rq->lock);
	return 0;
4567 4568 4569
}

#ifdef CONFIG_NO_HZ
4570 4571 4572 4573 4574 4575
/*
 * idle load balancing details
 * - 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.
 */
4576
static struct {
4577
	cpumask_var_t idle_cpus_mask;
4578
	atomic_t nr_cpus;
4579 4580
	unsigned long next_balance;     /* in jiffy units */
} nohz ____cacheline_aligned;
4581

4582
static inline int find_new_ilb(int call_cpu)
4583
{
4584
	int ilb = cpumask_first(nohz.idle_cpus_mask);
4585

4586 4587 4588 4589
	if (ilb < nr_cpu_ids && idle_cpu(ilb))
		return ilb;

	return nr_cpu_ids;
4590 4591
}

4592 4593 4594 4595 4596 4597 4598 4599 4600 4601 4602
/*
 * 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++;

4603
	ilb_cpu = find_new_ilb(cpu);
4604

4605 4606
	if (ilb_cpu >= nr_cpu_ids)
		return;
4607

4608
	if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu)))
4609 4610 4611 4612 4613 4614 4615 4616
		return;
	/*
	 * 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);
4617 4618 4619
	return;
}

4620
static inline void nohz_balance_exit_idle(int cpu)
4621 4622 4623 4624 4625 4626 4627 4628
{
	if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
		cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
		atomic_dec(&nohz.nr_cpus);
		clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
	}
}

4629 4630 4631 4632 4633 4634 4635 4636 4637 4638 4639 4640 4641 4642 4643 4644 4645 4646 4647 4648 4649 4650 4651 4652 4653 4654 4655 4656 4657 4658
static inline void set_cpu_sd_state_busy(void)
{
	struct sched_domain *sd;
	int cpu = smp_processor_id();

	if (!test_bit(NOHZ_IDLE, nohz_flags(cpu)))
		return;
	clear_bit(NOHZ_IDLE, nohz_flags(cpu));

	rcu_read_lock();
	for_each_domain(cpu, sd)
		atomic_inc(&sd->groups->sgp->nr_busy_cpus);
	rcu_read_unlock();
}

void set_cpu_sd_state_idle(void)
{
	struct sched_domain *sd;
	int cpu = smp_processor_id();

	if (test_bit(NOHZ_IDLE, nohz_flags(cpu)))
		return;
	set_bit(NOHZ_IDLE, nohz_flags(cpu));

	rcu_read_lock();
	for_each_domain(cpu, sd)
		atomic_dec(&sd->groups->sgp->nr_busy_cpus);
	rcu_read_unlock();
}

4659
/*
4660
 * This routine will record that the cpu is going idle with tick stopped.
4661
 * This info will be used in performing idle load balancing in the future.
4662
 */
4663
void nohz_balance_enter_idle(int cpu)
4664
{
4665 4666 4667 4668 4669 4670
	/*
	 * If this cpu is going down, then nothing needs to be done.
	 */
	if (!cpu_active(cpu))
		return;

4671 4672
	if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
		return;
4673

4674 4675 4676
	cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
	atomic_inc(&nohz.nr_cpus);
	set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
4677
}
4678 4679 4680 4681 4682 4683

static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
					unsigned long action, void *hcpu)
{
	switch (action & ~CPU_TASKS_FROZEN) {
	case CPU_DYING:
4684
		nohz_balance_exit_idle(smp_processor_id());
4685 4686 4687 4688 4689
		return NOTIFY_OK;
	default:
		return NOTIFY_DONE;
	}
}
4690 4691 4692 4693
#endif

static DEFINE_SPINLOCK(balancing);

4694 4695 4696 4697
/*
 * 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.
 */
4698
void update_max_interval(void)
4699 4700 4701 4702
{
	max_load_balance_interval = HZ*num_online_cpus()/10;
}

4703 4704 4705 4706 4707 4708 4709 4710 4711 4712 4713
/*
 * 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;
4714
	struct sched_domain *sd;
4715 4716 4717 4718 4719
	/* Earliest time when we have to do rebalance again */
	unsigned long next_balance = jiffies + 60*HZ;
	int update_next_balance = 0;
	int need_serialize;

P
Peter Zijlstra 已提交
4720 4721
	update_shares(cpu);

4722
	rcu_read_lock();
4723 4724 4725 4726 4727 4728 4729 4730 4731 4732
	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);
4733
		interval = clamp(interval, 1UL, max_load_balance_interval);
4734 4735 4736 4737 4738 4739 4740 4741 4742 4743 4744 4745

		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
4746
				 * longer idle.
4747 4748 4749 4750 4751 4752 4753 4754 4755 4756 4757 4758 4759 4760 4761 4762 4763 4764 4765 4766 4767
				 */
				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;
	}
4768
	rcu_read_unlock();
4769 4770 4771 4772 4773 4774 4775 4776 4777 4778

	/*
	 * 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;
}

4779
#ifdef CONFIG_NO_HZ
4780
/*
4781
 * In CONFIG_NO_HZ case, the idle balance kickee will do the
4782 4783
 * rebalancing for all the cpus for whom scheduler ticks are stopped.
 */
4784 4785 4786 4787 4788 4789
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;

4790 4791 4792
	if (idle != CPU_IDLE ||
	    !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
		goto end;
4793 4794

	for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
4795
		if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
4796 4797 4798 4799 4800 4801 4802
			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.
		 */
4803
		if (need_resched())
4804 4805
			break;

V
Vincent Guittot 已提交
4806 4807 4808 4809 4810 4811
		rq = cpu_rq(balance_cpu);

		raw_spin_lock_irq(&rq->lock);
		update_rq_clock(rq);
		update_idle_cpu_load(rq);
		raw_spin_unlock_irq(&rq->lock);
4812 4813 4814 4815 4816 4817 4818

		rebalance_domains(balance_cpu, CPU_IDLE);

		if (time_after(this_rq->next_balance, rq->next_balance))
			this_rq->next_balance = rq->next_balance;
	}
	nohz.next_balance = this_rq->next_balance;
4819 4820
end:
	clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu));
4821 4822 4823
}

/*
4824 4825 4826 4827 4828 4829 4830
 * Current heuristic for kicking the idle load balancer in the presence
 * of an idle cpu is the system.
 *   - This rq has more than one task.
 *   - At any scheduler domain level, this cpu's scheduler group has multiple
 *     busy cpu's exceeding the group's power.
 *   - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
 *     domain span are idle.
4831 4832 4833 4834
 */
static inline int nohz_kick_needed(struct rq *rq, int cpu)
{
	unsigned long now = jiffies;
4835
	struct sched_domain *sd;
4836

4837
	if (unlikely(idle_cpu(cpu)))
4838 4839
		return 0;

4840 4841 4842 4843
       /*
	* We may be recently in ticked or tickless idle mode. At the first
	* busy tick after returning from idle, we will update the busy stats.
	*/
4844
	set_cpu_sd_state_busy();
4845
	nohz_balance_exit_idle(cpu);
4846 4847 4848 4849 4850 4851 4852

	/*
	 * None are in tickless mode and hence no need for NOHZ idle load
	 * balancing.
	 */
	if (likely(!atomic_read(&nohz.nr_cpus)))
		return 0;
4853 4854

	if (time_before(now, nohz.next_balance))
4855 4856
		return 0;

4857 4858
	if (rq->nr_running >= 2)
		goto need_kick;
4859

4860
	rcu_read_lock();
4861 4862 4863 4864
	for_each_domain(cpu, sd) {
		struct sched_group *sg = sd->groups;
		struct sched_group_power *sgp = sg->sgp;
		int nr_busy = atomic_read(&sgp->nr_busy_cpus);
4865

4866
		if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
4867
			goto need_kick_unlock;
4868 4869 4870 4871

		if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
		    && (cpumask_first_and(nohz.idle_cpus_mask,
					  sched_domain_span(sd)) < cpu))
4872
			goto need_kick_unlock;
4873 4874 4875

		if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
			break;
4876
	}
4877
	rcu_read_unlock();
4878
	return 0;
4879 4880 4881

need_kick_unlock:
	rcu_read_unlock();
4882 4883
need_kick:
	return 1;
4884 4885 4886 4887 4888 4889 4890 4891 4892
}
#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).
 */
4893 4894 4895 4896
static void run_rebalance_domains(struct softirq_action *h)
{
	int this_cpu = smp_processor_id();
	struct rq *this_rq = cpu_rq(this_cpu);
4897
	enum cpu_idle_type idle = this_rq->idle_balance ?
4898 4899 4900 4901 4902
						CPU_IDLE : CPU_NOT_IDLE;

	rebalance_domains(this_cpu, idle);

	/*
4903
	 * If this cpu has a pending nohz_balance_kick, then do the
4904 4905 4906
	 * balancing on behalf of the other idle cpus whose ticks are
	 * stopped.
	 */
4907
	nohz_idle_balance(this_cpu, idle);
4908 4909 4910 4911
}

static inline int on_null_domain(int cpu)
{
4912
	return !rcu_dereference_sched(cpu_rq(cpu)->sd);
4913 4914 4915 4916 4917
}

/*
 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
 */
4918
void trigger_load_balance(struct rq *rq, int cpu)
4919 4920 4921 4922 4923
{
	/* 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);
4924
#ifdef CONFIG_NO_HZ
4925
	if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu)))
4926 4927
		nohz_balancer_kick(cpu);
#endif
4928 4929
}

4930 4931 4932 4933 4934 4935 4936 4937
static void rq_online_fair(struct rq *rq)
{
	update_sysctl();
}

static void rq_offline_fair(struct rq *rq)
{
	update_sysctl();
4938 4939 4940

	/* Ensure any throttled groups are reachable by pick_next_task */
	unthrottle_offline_cfs_rqs(rq);
4941 4942
}

4943
#endif /* CONFIG_SMP */
4944

4945 4946 4947
/*
 * scheduler tick hitting a task of our scheduling class:
 */
P
Peter Zijlstra 已提交
4948
static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
4949 4950 4951 4952 4953 4954
{
	struct cfs_rq *cfs_rq;
	struct sched_entity *se = &curr->se;

	for_each_sched_entity(se) {
		cfs_rq = cfs_rq_of(se);
P
Peter Zijlstra 已提交
4955
		entity_tick(cfs_rq, se, queued);
4956 4957 4958 4959
	}
}

/*
P
Peter Zijlstra 已提交
4960 4961 4962
 * called on fork with the child task as argument from the parent's context
 *  - child not yet on the tasklist
 *  - preemption disabled
4963
 */
P
Peter Zijlstra 已提交
4964
static void task_fork_fair(struct task_struct *p)
4965
{
4966 4967
	struct cfs_rq *cfs_rq;
	struct sched_entity *se = &p->se, *curr;
4968
	int this_cpu = smp_processor_id();
P
Peter Zijlstra 已提交
4969 4970 4971
	struct rq *rq = this_rq();
	unsigned long flags;

4972
	raw_spin_lock_irqsave(&rq->lock, flags);
4973

4974 4975
	update_rq_clock(rq);

4976 4977 4978
	cfs_rq = task_cfs_rq(current);
	curr = cfs_rq->curr;

4979 4980
	if (unlikely(task_cpu(p) != this_cpu)) {
		rcu_read_lock();
P
Peter Zijlstra 已提交
4981
		__set_task_cpu(p, this_cpu);
4982 4983
		rcu_read_unlock();
	}
4984

4985
	update_curr(cfs_rq);
P
Peter Zijlstra 已提交
4986

4987 4988
	if (curr)
		se->vruntime = curr->vruntime;
4989
	place_entity(cfs_rq, se, 1);
4990

P
Peter Zijlstra 已提交
4991
	if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
D
Dmitry Adamushko 已提交
4992
		/*
4993 4994 4995
		 * Upon rescheduling, sched_class::put_prev_task() will place
		 * 'current' within the tree based on its new key value.
		 */
4996
		swap(curr->vruntime, se->vruntime);
4997
		resched_task(rq->curr);
4998
	}
4999

5000 5001
	se->vruntime -= cfs_rq->min_vruntime;

5002
	raw_spin_unlock_irqrestore(&rq->lock, flags);
5003 5004
}

5005 5006 5007 5008
/*
 * Priority of the task has changed. Check to see if we preempt
 * the current task.
 */
P
Peter Zijlstra 已提交
5009 5010
static void
prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
5011
{
P
Peter Zijlstra 已提交
5012 5013 5014
	if (!p->se.on_rq)
		return;

5015 5016 5017 5018 5019
	/*
	 * 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
	 */
P
Peter Zijlstra 已提交
5020
	if (rq->curr == p) {
5021 5022 5023
		if (p->prio > oldprio)
			resched_task(rq->curr);
	} else
5024
		check_preempt_curr(rq, p, 0);
5025 5026
}

P
Peter Zijlstra 已提交
5027 5028 5029 5030 5031 5032 5033 5034 5035 5036 5037 5038 5039 5040 5041 5042 5043 5044 5045 5046 5047 5048 5049 5050
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;
	}
}

5051 5052 5053
/*
 * We switched to the sched_fair class.
 */
P
Peter Zijlstra 已提交
5054
static void switched_to_fair(struct rq *rq, struct task_struct *p)
5055
{
P
Peter Zijlstra 已提交
5056 5057 5058
	if (!p->se.on_rq)
		return;

5059 5060 5061 5062 5063
	/*
	 * 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.
	 */
P
Peter Zijlstra 已提交
5064
	if (rq->curr == p)
5065 5066
		resched_task(rq->curr);
	else
5067
		check_preempt_curr(rq, p, 0);
5068 5069
}

5070 5071 5072 5073 5074 5075 5076 5077 5078
/* 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;

5079 5080 5081 5082 5083 5084 5085
	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);
	}
5086 5087
}

5088 5089 5090 5091 5092 5093 5094 5095 5096
void init_cfs_rq(struct cfs_rq *cfs_rq)
{
	cfs_rq->tasks_timeline = RB_ROOT;
	cfs_rq->min_vruntime = (u64)(-(1LL << 20));
#ifndef CONFIG_64BIT
	cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
#endif
}

P
Peter Zijlstra 已提交
5097
#ifdef CONFIG_FAIR_GROUP_SCHED
5098
static void task_move_group_fair(struct task_struct *p, int on_rq)
P
Peter Zijlstra 已提交
5099
{
5100 5101 5102 5103 5104 5105 5106 5107 5108 5109 5110 5111 5112
	/*
	 * 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.
	 */
5113 5114 5115 5116 5117 5118
	/*
	 * When !on_rq, vruntime of the task has usually NOT been normalized.
	 * But there are some cases where it has already been normalized:
	 *
	 * - Moving a forked child which is waiting for being woken up by
	 *   wake_up_new_task().
5119 5120
	 * - Moving a task which has been woken up by try_to_wake_up() and
	 *   waiting for actually being woken up by sched_ttwu_pending().
5121 5122 5123 5124
	 *
	 * To prevent boost or penalty in the new cfs_rq caused by delta
	 * min_vruntime between the two cfs_rqs, we skip vruntime adjustment.
	 */
5125
	if (!on_rq && (!p->se.sum_exec_runtime || p->state == TASK_WAKING))
5126 5127
		on_rq = 1;

5128 5129 5130
	if (!on_rq)
		p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime;
	set_task_rq(p, task_cpu(p));
5131
	if (!on_rq)
5132
		p->se.vruntime += cfs_rq_of(&p->se)->min_vruntime;
P
Peter Zijlstra 已提交
5133
}
5134 5135 5136 5137 5138 5139 5140 5141 5142 5143 5144 5145 5146 5147 5148 5149 5150 5151 5152 5153 5154 5155 5156 5157 5158 5159 5160 5161 5162 5163 5164 5165 5166 5167 5168 5169 5170 5171 5172 5173 5174 5175 5176 5177 5178 5179 5180 5181 5182 5183 5184 5185 5186 5187 5188 5189 5190 5191 5192 5193 5194 5195 5196 5197 5198 5199 5200 5201 5202 5203 5204 5205 5206 5207 5208 5209 5210 5211 5212 5213 5214 5215 5216 5217 5218 5219

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;
P
Peter Zijlstra 已提交
5220
#endif
5221 5222 5223 5224 5225 5226 5227 5228 5229 5230 5231 5232 5233 5234 5235 5236 5237 5238 5239 5240 5241 5242 5243 5244 5245 5246 5247 5248 5249 5250 5251 5252 5253 5254 5255 5256 5257 5258 5259 5260 5261 5262 5263 5264 5265 5266 5267 5268 5269 5270 5271 5272 5273 5274 5275 5276 5277 5278 5279 5280 5281 5282 5283 5284 5285 5286 5287 5288
	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 */

P
Peter Zijlstra 已提交
5289

5290
static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
5291 5292 5293 5294 5295 5296 5297 5298 5299 5300 5301 5302 5303 5304
{
	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;
}

5305 5306 5307
/*
 * All the scheduling class methods:
 */
5308
const struct sched_class fair_sched_class = {
5309
	.next			= &idle_sched_class,
5310 5311 5312
	.enqueue_task		= enqueue_task_fair,
	.dequeue_task		= dequeue_task_fair,
	.yield_task		= yield_task_fair,
5313
	.yield_to_task		= yield_to_task_fair,
5314

I
Ingo Molnar 已提交
5315
	.check_preempt_curr	= check_preempt_wakeup,
5316 5317 5318 5319

	.pick_next_task		= pick_next_task_fair,
	.put_prev_task		= put_prev_task_fair,

5320
#ifdef CONFIG_SMP
L
Li Zefan 已提交
5321 5322
	.select_task_rq		= select_task_rq_fair,

5323 5324
	.rq_online		= rq_online_fair,
	.rq_offline		= rq_offline_fair,
5325 5326

	.task_waking		= task_waking_fair,
5327
#endif
5328

5329
	.set_curr_task          = set_curr_task_fair,
5330
	.task_tick		= task_tick_fair,
P
Peter Zijlstra 已提交
5331
	.task_fork		= task_fork_fair,
5332 5333

	.prio_changed		= prio_changed_fair,
P
Peter Zijlstra 已提交
5334
	.switched_from		= switched_from_fair,
5335
	.switched_to		= switched_to_fair,
P
Peter Zijlstra 已提交
5336

5337 5338
	.get_rr_interval	= get_rr_interval_fair,

P
Peter Zijlstra 已提交
5339
#ifdef CONFIG_FAIR_GROUP_SCHED
5340
	.task_move_group	= task_move_group_fair,
P
Peter Zijlstra 已提交
5341
#endif
5342 5343 5344
};

#ifdef CONFIG_SCHED_DEBUG
5345
void print_cfs_stats(struct seq_file *m, int cpu)
5346 5347 5348
{
	struct cfs_rq *cfs_rq;

5349
	rcu_read_lock();
5350
	for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
5351
		print_cfs_rq(m, cpu, cfs_rq);
5352
	rcu_read_unlock();
5353 5354
}
#endif
5355 5356 5357 5358 5359 5360 5361

__init void init_sched_fair_class(void)
{
#ifdef CONFIG_SMP
	open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);

#ifdef CONFIG_NO_HZ
5362
	nohz.next_balance = jiffies;
5363
	zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
5364
	cpu_notifier(sched_ilb_notifier, 0);
5365 5366 5367 5368
#endif
#endif /* SMP */

}