Initial import

1 files changed, 8310 insertions, 0 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
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+++ b/kernel/sched/fair.c
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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>
+ *
+ *  Adaptive scheduling granularity, math enhancements by Peter Zijlstra
+ *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ */
+
+#include <linux/latencytop.h>
+#include <linux/sched.h>
+#include <linux/cpumask.h>
+#include <linux/cpuidle.h>
+#include <linux/slab.h>
+#include <linux/profile.h>
+#include <linux/interrupt.h>
+#include <linux/mempolicy.h>
+#include <linux/migrate.h>
+#include <linux/task_work.h>
+
+#include <trace/events/sched.h>
+
+#include "sched.h"
+
+/*
+ * Targeted preemption latency for CPU-bound tasks:
+ * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
+ *
+ * NOTE: this latency value is not the same as the concept of
+ * 'timeslice length' - timeslices in CFS are of variable length
+ * and have no persistent notion like in traditional, time-slice
+ * based scheduling concepts.
+ *
+ * (to see the precise effective timeslice length of your workload,
+ *  run vmstat and monitor the context-switches (cs) field)
+ */
+#ifdef CONFIG_PCK_INTERACTIVE
+unsigned int sysctl_sched_latency = 3000000ULL;
+unsigned int normalized_sysctl_sched_latency = 3000000ULL;
+#else
+unsigned int sysctl_sched_latency = 6000000ULL;
+unsigned int normalized_sysctl_sched_latency = 6000000ULL;
+#endif
+
+/*
+ * The initial- and re-scaling of tunables is configurable
+ * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
+ *
+ * Options are:
+ * SCHED_TUNABLESCALING_NONE - unscaled, always *1
+ * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
+ * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
+ */
+enum sched_tunable_scaling sysctl_sched_tunable_scaling
+	= SCHED_TUNABLESCALING_LOG;
+
+/*
+ * Minimal preemption granularity for CPU-bound tasks:
+ * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
+ */
+#ifdef CONFIG_PCK_INTERACTIVE
+unsigned int sysctl_sched_min_granularity = 300000ULL;
+unsigned int normalized_sysctl_sched_min_granularity = 300000ULL;
+#else
+unsigned int sysctl_sched_min_granularity = 750000ULL;
+unsigned int normalized_sysctl_sched_min_granularity = 750000ULL;
+#endif
+
+/*
+ * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
+ */
+#ifdef CONFIG_PCK_INTERACTIVE
+static unsigned int sched_nr_latency = 10;
+#else
+static unsigned int sched_nr_latency = 8;
+#endif
+
+/*
+ * After fork, child runs first. If set to 0 (default) then
+ * parent will (try to) run first.
+ */
+unsigned int sysctl_sched_child_runs_first __read_mostly;
+
+/*
+ * SCHED_OTHER wake-up granularity.
+ * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
+ *
+ * This option delays the preemption effects of decoupled workloads
+ * and reduces their over-scheduling. Synchronous workloads will still
+ * have immediate wakeup/sleep latencies.
+ */
+#ifdef CONFIG_PCK_INTERACTIVE
+unsigned int sysctl_sched_wakeup_granularity = 500000UL;
+unsigned int normalized_sysctl_sched_wakeup_granularity = 500000UL;
+
+const_debug unsigned int sysctl_sched_migration_cost = 250000UL;
+#else
+unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
+unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
+
+const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
+#endif
+
+/*
+ * The exponential sliding  window over which load is averaged for shares
+ * distribution.
+ * (default: 10msec)
+ */
+unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
+
+#ifdef CONFIG_CFS_BANDWIDTH
+/*
+ * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
+ * each time a cfs_rq requests quota.
+ *
+ * Note: in the case that the slice exceeds the runtime remaining (either due
+ * to consumption or the quota being specified to be smaller than the slice)
+ * we will always only issue the remaining available time.
+ *
+ * default: 5 msec, units: microseconds
+  */
+#ifdef CONFIG_PCK_INTERACTIVE
+unsigned int sysctl_sched_cfs_bandwidth_slice = 3000UL;
+#else
+unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL;
+#endif
+#endif
+
+static inline void update_load_add(struct load_weight *lw, unsigned long inc)
+{
+	lw->weight += inc;
+	lw->inv_weight = 0;
+}
+
+static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
+{
+	lw->weight -= dec;
+	lw->inv_weight = 0;
+}
+
+static inline void update_load_set(struct load_weight *lw, unsigned long w)
+{
+	lw->weight = w;
+	lw->inv_weight = 0;
+}
+
+/*
+ * 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();
+}
+
+#define WMULT_CONST	(~0U)
+#define WMULT_SHIFT	32
+
+static void __update_inv_weight(struct load_weight *lw)
+{
+	unsigned long w;
+
+	if (likely(lw->inv_weight))
+		return;
+
+	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;
+}
+
+/*
+ * delta_exec * weight / lw.weight
+ *   OR
+ * (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT
+ *
+ * Either weight := NICE_0_LOAD and lw \e prio_to_wmult[], in which case
+ * we're guaranteed shift stays positive because inv_weight is guaranteed to
+ * fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22.
+ *
+ * Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus
+ * weight/lw.weight <= 1, and therefore our shift will also be positive.
+ */
+static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight *lw)
+{
+	u64 fact = scale_load_down(weight);
+	int shift = WMULT_SHIFT;
+
+	__update_inv_weight(lw);
+
+	if (unlikely(fact >> 32)) {
+		while (fact >> 32) {
+			fact >>= 1;
+			shift--;
+		}
+	}
+
+	/* hint to use a 32x32->64 mul */
+	fact = (u64)(u32)fact * lw->inv_weight;
+
+	while (fact >> 32) {
+		fact >>= 1;
+		shift--;
+	}
+
+	return mul_u64_u32_shr(delta_exec, fact, shift);
+}
+
+
+const struct sched_class fair_sched_class;
+
+/**************************************************************
+ * CFS operations on generic schedulable entities:
+ */
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+
+/* cpu runqueue to which this cfs_rq is attached */
+static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
+{
+	return cfs_rq->rq;
+}
+
+/* An entity is a task if it doesn't "own" a runqueue */
+#define entity_is_task(se)	(!se->my_q)
+
+static inline struct task_struct *task_of(struct sched_entity *se)
+{
+#ifdef CONFIG_SCHED_DEBUG
+	WARN_ON_ONCE(!entity_is_task(se));
+#endif
+	return container_of(se, struct task_struct, se);
+}
+
+/* Walk up scheduling entities hierarchy */
+#define for_each_sched_entity(se) \
+		for (; se; se = se->parent)
+
+static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
+{
+	return p->se.cfs_rq;
+}
+
+/* runqueue on which this entity is (to be) queued */
+static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
+{
+	return se->cfs_rq;
+}
+
+/* runqueue "owned" by this group */
+static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
+{
+	return grp->my_q;
+}
+
+static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
+				       int force_update);
+
+static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
+{
+	if (!cfs_rq->on_list) {
+		/*
+		 * Ensure we either appear before our parent (if already
+		 * enqueued) or force our parent to appear after us when it is
+		 * enqueued.  The fact that we always enqueue bottom-up
+		 * reduces this to two cases.
+		 */
+		if (cfs_rq->tg->parent &&
+		    cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) {
+			list_add_rcu(&cfs_rq->leaf_cfs_rq_list,
+				&rq_of(cfs_rq)->leaf_cfs_rq_list);
+		} else {
+			list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
+				&rq_of(cfs_rq)->leaf_cfs_rq_list);
+		}
+
+		cfs_rq->on_list = 1;
+		/* We should have no load, but we need to update last_decay. */
+		update_cfs_rq_blocked_load(cfs_rq, 0);
+	}
+}
+
+static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
+{
+	if (cfs_rq->on_list) {
+		list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
+		cfs_rq->on_list = 0;
+	}
+}
+
+/* Iterate thr' all leaf cfs_rq's on a runqueue */
+#define for_each_leaf_cfs_rq(rq, cfs_rq) \
+	list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
+
+/* Do the two (enqueued) entities belong to the same group ? */
+static inline struct cfs_rq *
+is_same_group(struct sched_entity *se, struct sched_entity *pse)
+{
+	if (se->cfs_rq == pse->cfs_rq)
+		return se->cfs_rq;
+
+	return NULL;
+}
+
+static inline struct sched_entity *parent_entity(struct sched_entity *se)
+{
+	return se->parent;
+}
+
+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 = (*se)->depth;
+	pse_depth = (*pse)->depth;
+
+	while (se_depth > pse_depth) {
+		se_depth--;
+		*se = parent_entity(*se);
+	}
+
+	while (pse_depth > se_depth) {
+		pse_depth--;
+		*pse = parent_entity(*pse);
+	}
+
+	while (!is_same_group(*se, *pse)) {
+		*se = parent_entity(*se);
+		*pse = parent_entity(*pse);
+	}
+}
+
+#else	/* !CONFIG_FAIR_GROUP_SCHED */
+
+static inline struct task_struct *task_of(struct sched_entity *se)
+{
+	return container_of(se, struct task_struct, se);
+}
+
+static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
+{
+	return container_of(cfs_rq, struct rq, cfs);
+}
+
+#define entity_is_task(se)	1
+
+#define for_each_sched_entity(se) \
+		for (; se; se = NULL)
+
+static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
+{
+	return &task_rq(p)->cfs;
+}
+
+static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
+{
+	struct task_struct *p = task_of(se);
+	struct rq *rq = task_rq(p);
+
+	return &rq->cfs;
+}
+
+/* runqueue "owned" by this group */
+static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
+{
+	return NULL;
+}
+
+static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
+{
+}
+
+static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
+{
+}
+
+#define for_each_leaf_cfs_rq(rq, cfs_rq) \
+		for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
+
+static inline struct sched_entity *parent_entity(struct sched_entity *se)
+{
+	return NULL;
+}
+
+static inline void
+find_matching_se(struct sched_entity **se, struct sched_entity **pse)
+{
+}
+
+#endif	/* CONFIG_FAIR_GROUP_SCHED */
+
+static __always_inline
+void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec);
+
+/**************************************************************
+ * Scheduling class tree data structure manipulation methods:
+ */
+
+static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime)
+{
+	s64 delta = (s64)(vruntime - max_vruntime);
+	if (delta > 0)
+		max_vruntime = vruntime;
+
+	return max_vruntime;
+}
+
+static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
+{
+	s64 delta = (s64)(vruntime - min_vruntime);
+	if (delta < 0)
+		min_vruntime = vruntime;
+
+	return min_vruntime;
+}
+
+static inline int entity_before(struct sched_entity *a,
+				struct sched_entity *b)
+{
+	return (s64)(a->vruntime - b->vruntime) < 0;
+}
+
+static void update_min_vruntime(struct cfs_rq *cfs_rq)
+{
+	u64 vruntime = cfs_rq->min_vruntime;
+
+	if (cfs_rq->curr)
+		vruntime = cfs_rq->curr->vruntime;
+
+	if (cfs_rq->rb_leftmost) {
+		struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost,
+						   struct sched_entity,
+						   run_node);
+
+		if (!cfs_rq->curr)
+			vruntime = se->vruntime;
+		else
+			vruntime = min_vruntime(vruntime, se->vruntime);
+	}
+
+	/* ensure we never gain time by being placed backwards. */
+	cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
+#ifndef CONFIG_64BIT
+	smp_wmb();
+	cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
+#endif
+}
+
+/*
+ * Enqueue an entity into the rb-tree:
+ */
+static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
+	struct rb_node *parent = NULL;
+	struct sched_entity *entry;
+	int leftmost = 1;
+
+	/*
+	 * Find the right place in the rbtree:
+	 */
+	while (*link) {
+		parent = *link;
+		entry = rb_entry(parent, struct sched_entity, run_node);
+		/*
+		 * We dont care about collisions. Nodes with
+		 * the same key stay together.
+		 */
+		if (entity_before(se, entry)) {
+			link = &parent->rb_left;
+		} else {
+			link = &parent->rb_right;
+			leftmost = 0;
+		}
+	}
+
+	/*
+	 * Maintain a cache of leftmost tree entries (it is frequently
+	 * used):
+	 */
+	if (leftmost)
+		cfs_rq->rb_leftmost = &se->run_node;
+
+	rb_link_node(&se->run_node, parent, link);
+	rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
+}
+
+static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	if (cfs_rq->rb_leftmost == &se->run_node) {
+		struct rb_node *next_node;
+
+		next_node = rb_next(&se->run_node);
+		cfs_rq->rb_leftmost = next_node;
+	}
+
+	rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
+}
+
+struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
+{
+	struct rb_node *left = cfs_rq->rb_leftmost;
+
+	if (!left)
+		return NULL;
+
+	return rb_entry(left, struct sched_entity, run_node);
+}
+
+static struct sched_entity *__pick_next_entity(struct sched_entity *se)
+{
+	struct rb_node *next = rb_next(&se->run_node);
+
+	if (!next)
+		return NULL;
+
+	return rb_entry(next, struct sched_entity, run_node);
+}
+
+#ifdef CONFIG_SCHED_DEBUG
+struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
+{
+	struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
+
+	if (!last)
+		return NULL;
+
+	return rb_entry(last, struct sched_entity, run_node);
+}
+
+/**************************************************************
+ * Scheduling class statistics methods:
+ */
+
+int sched_proc_update_handler(struct ctl_table *table, int write,
+		void __user *buffer, size_t *lenp,
+		loff_t *ppos)
+{
+	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	int factor = get_update_sysctl_factor();
+
+	if (ret || !write)
+		return ret;
+
+	sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
+					sysctl_sched_min_granularity);
+
+#define WRT_SYSCTL(name) \
+	(normalized_sysctl_##name = sysctl_##name / (factor))
+	WRT_SYSCTL(sched_min_granularity);
+	WRT_SYSCTL(sched_latency);
+	WRT_SYSCTL(sched_wakeup_granularity);
+#undef WRT_SYSCTL
+
+	return 0;
+}
+#endif
+
+/*
+ * delta /= w
+ */
+static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se)
+{
+	if (unlikely(se->load.weight != NICE_0_LOAD))
+		delta = __calc_delta(delta, NICE_0_LOAD, &se->load);
+
+	return delta;
+}
+
+/*
+ * The idea is to set a period in which each task runs once.
+ *
+ * When there are too many tasks (sched_nr_latency) we have to stretch
+ * this period because otherwise the slices get too small.
+ *
+ * p = (nr <= nl) ? l : l*nr/nl
+ */
+static u64 __sched_period(unsigned long nr_running)
+{
+	u64 period = sysctl_sched_latency;
+	unsigned long nr_latency = sched_nr_latency;
+
+	if (unlikely(nr_running > nr_latency)) {
+		period = sysctl_sched_min_granularity;
+		period *= nr_running;
+	}
+
+	return period;
+}
+
+/*
+ * We calculate the wall-time slice from the period by taking a part
+ * proportional to the weight.
+ *
+ * s = p*P[w/rw]
+ */
+static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq);
+
+	for_each_sched_entity(se) {
+		struct load_weight *load;
+		struct load_weight lw;
+
+		cfs_rq = cfs_rq_of(se);
+		load = &cfs_rq->load;
+
+		if (unlikely(!se->on_rq)) {
+			lw = cfs_rq->load;
+
+			update_load_add(&lw, se->load.weight);
+			load = &lw;
+		}
+		slice = __calc_delta(slice, se->load.weight, load);
+	}
+	return slice;
+}
+
+/*
+ * We calculate the vruntime slice of a to-be-inserted task.
+ *
+ * vs = s/w
+ */
+static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	return calc_delta_fair(sched_slice(cfs_rq, se), se);
+}
+
+#ifdef CONFIG_SMP
+static int select_idle_sibling(struct task_struct *p, int cpu);
+static unsigned long task_h_load(struct task_struct *p);
+
+static inline void __update_task_entity_contrib(struct sched_entity *se);
+static inline void __update_task_entity_utilization(struct sched_entity *se);
+
+/* Give new task start runnable values to heavy its load in infant time */
+void init_task_runnable_average(struct task_struct *p)
+{
+	u32 slice;
+
+	slice = sched_slice(task_cfs_rq(p), &p->se) >> 10;
+	p->se.avg.runnable_avg_sum = p->se.avg.running_avg_sum = slice;
+	p->se.avg.avg_period = slice;
+	__update_task_entity_contrib(&p->se);
+	__update_task_entity_utilization(&p->se);
+}
+#else
+void init_task_runnable_average(struct task_struct *p)
+{
+}
+#endif
+
+/*
+ * Update the current task's runtime statistics.
+ */
+static void update_curr(struct cfs_rq *cfs_rq)
+{
+	struct sched_entity *curr = cfs_rq->curr;
+	u64 now = rq_clock_task(rq_of(cfs_rq));
+	u64 delta_exec;
+
+	if (unlikely(!curr))
+		return;
+
+	delta_exec = now - curr->exec_start;
+	if (unlikely((s64)delta_exec <= 0))
+		return;
+
+	curr->exec_start = now;
+
+	schedstat_set(curr->statistics.exec_max,
+		      max(delta_exec, curr->statistics.exec_max));
+
+	curr->sum_exec_runtime += delta_exec;
+	schedstat_add(cfs_rq, exec_clock, delta_exec);
+
+	curr->vruntime += calc_delta_fair(delta_exec, curr);
+	update_min_vruntime(cfs_rq);
+
+	if (entity_is_task(curr)) {
+		struct task_struct *curtask = task_of(curr);
+
+		trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
+		cpuacct_charge(curtask, delta_exec);
+		account_group_exec_runtime(curtask, delta_exec);
+	}
+
+	account_cfs_rq_runtime(cfs_rq, delta_exec);
+}
+
+static void update_curr_fair(struct rq *rq)
+{
+	update_curr(cfs_rq_of(&rq->curr->se));
+}
+
+static inline void
+update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	schedstat_set(se->statistics.wait_start, rq_clock(rq_of(cfs_rq)));
+}
+
+/*
+ * Task is being enqueued - update stats:
+ */
+static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	/*
+	 * Are we enqueueing a waiting task? (for current tasks
+	 * a dequeue/enqueue event is a NOP)
+	 */
+	if (se != cfs_rq->curr)
+		update_stats_wait_start(cfs_rq, se);
+}
+
+static void
+update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max,
+			rq_clock(rq_of(cfs_rq)) - 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_clock(rq_of(cfs_rq)) - se->statistics.wait_start);
+#ifdef CONFIG_SCHEDSTATS
+	if (entity_is_task(se)) {
+		trace_sched_stat_wait(task_of(se),
+			rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start);
+	}
+#endif
+	schedstat_set(se->statistics.wait_start, 0);
+}
+
+static inline void
+update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	/*
+	 * Mark the end of the wait period if dequeueing a
+	 * waiting task:
+	 */
+	if (se != cfs_rq->curr)
+		update_stats_wait_end(cfs_rq, se);
+}
+
+/*
+ * We are picking a new current task - update its stats:
+ */
+static inline void
+update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	/*
+	 * We are starting a new run period:
+	 */
+	se->exec_start = rq_clock_task(rq_of(cfs_rq));
+}
+
+/**************************************************
+ * Scheduling class queueing methods:
+ */
+
+#ifdef CONFIG_NUMA_BALANCING
+/*
+ * Approximate time to scan a full NUMA task in ms. The task scan period is
+ * calculated based on the tasks virtual memory size and
+ * numa_balancing_scan_size.
+ */
+unsigned int sysctl_numa_balancing_scan_period_min = 1000;
+unsigned int sysctl_numa_balancing_scan_period_max = 60000;
+
+/* Portion of address space to scan in MB */
+unsigned int sysctl_numa_balancing_scan_size = 256;
+
+/* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */
+unsigned int sysctl_numa_balancing_scan_delay = 1000;
+
+static unsigned int task_nr_scan_windows(struct task_struct *p)
+{
+	unsigned long rss = 0;
+	unsigned long nr_scan_pages;
+
+	/*
+	 * Calculations based on RSS as non-present and empty pages are skipped
+	 * by the PTE scanner and NUMA hinting faults should be trapped based
+	 * on resident pages
+	 */
+	nr_scan_pages = sysctl_numa_balancing_scan_size << (20 - PAGE_SHIFT);
+	rss = get_mm_rss(p->mm);
+	if (!rss)
+		rss = nr_scan_pages;
+
+	rss = round_up(rss, nr_scan_pages);
+	return rss / nr_scan_pages;
+}
+
+/* For sanitys sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */
+#define MAX_SCAN_WINDOW 2560
+
+static unsigned int task_scan_min(struct task_struct *p)
+{
+	unsigned int scan_size = ACCESS_ONCE(sysctl_numa_balancing_scan_size);
+	unsigned int scan, floor;
+	unsigned int windows = 1;
+
+	if (scan_size < MAX_SCAN_WINDOW)
+		windows = MAX_SCAN_WINDOW / scan_size;
+	floor = 1000 / windows;
+
+	scan = sysctl_numa_balancing_scan_period_min / task_nr_scan_windows(p);
+	return max_t(unsigned int, floor, scan);
+}
+
+static unsigned int task_scan_max(struct task_struct *p)
+{
+	unsigned int smin = task_scan_min(p);
+	unsigned int smax;
+
+	/* Watch for min being lower than max due to floor calculations */
+	smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p);
+	return max(smin, smax);
+}
+
+static void account_numa_enqueue(struct rq *rq, struct task_struct *p)
+{
+	rq->nr_numa_running += (p->numa_preferred_nid != -1);
+	rq->nr_preferred_running += (p->numa_preferred_nid == task_node(p));
+}
+
+static void account_numa_dequeue(struct rq *rq, struct task_struct *p)
+{
+	rq->nr_numa_running -= (p->numa_preferred_nid != -1);
+	rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p));
+}
+
+struct numa_group {
+	atomic_t refcount;
+
+	spinlock_t lock; /* nr_tasks, tasks */
+	int nr_tasks;
+	pid_t gid;
+
+	struct rcu_head rcu;
+	nodemask_t active_nodes;
+	unsigned long total_faults;
+	/*
+	 * Faults_cpu is used to decide whether memory should move
+	 * towards the CPU. As a consequence, these stats are weighted
+	 * more by CPU use than by memory faults.
+	 */
+	unsigned long *faults_cpu;
+	unsigned long faults[0];
+};
+
+/* Shared or private faults. */
+#define NR_NUMA_HINT_FAULT_TYPES 2
+
+/* Memory and CPU locality */
+#define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2)
+
+/* Averaged statistics, and temporary buffers. */
+#define NR_NUMA_HINT_FAULT_BUCKETS (NR_NUMA_HINT_FAULT_STATS * 2)
+
+pid_t task_numa_group_id(struct task_struct *p)
+{
+	return p->numa_group ? p->numa_group->gid : 0;
+}
+
+/*
+ * The averaged statistics, shared & private, memory & cpu,
+ * occupy the first half of the array. The second half of the
+ * array is for current counters, which are averaged into the
+ * first set by task_numa_placement.
+ */
+static inline int task_faults_idx(enum numa_faults_stats s, int nid, int priv)
+{
+	return NR_NUMA_HINT_FAULT_TYPES * (s * nr_node_ids + nid) + priv;
+}
+
+static inline unsigned long task_faults(struct task_struct *p, int nid)
+{
+	if (!p->numa_faults)
+		return 0;
+
+	return p->numa_faults[task_faults_idx(NUMA_MEM, nid, 0)] +
+		p->numa_faults[task_faults_idx(NUMA_MEM, nid, 1)];
+}
+
+static inline unsigned long group_faults(struct task_struct *p, int nid)
+{
+	if (!p->numa_group)
+		return 0;
+
+	return p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 0)] +
+		p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 1)];
+}
+
+static inline unsigned long group_faults_cpu(struct numa_group *group, int nid)
+{
+	return group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 0)] +
+		group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 1)];
+}
+
+/* Handle placement on systems where not all nodes are directly connected. */
+static unsigned long score_nearby_nodes(struct task_struct *p, int nid,
+					int maxdist, bool task)
+{
+	unsigned long score = 0;
+	int node;
+
+	/*
+	 * All nodes are directly connected, and the same distance
+	 * from each other. No need for fancy placement algorithms.
+	 */
+	if (sched_numa_topology_type == NUMA_DIRECT)
+		return 0;
+
+	/*
+	 * This code is called for each node, introducing N^2 complexity,
+	 * which should be ok given the number of nodes rarely exceeds 8.
+	 */
+	for_each_online_node(node) {
+		unsigned long faults;
+		int dist = node_distance(nid, node);
+
+		/*
+		 * The furthest away nodes in the system are not interesting
+		 * for placement; nid was already counted.
+		 */
+		if (dist == sched_max_numa_distance || node == nid)
+			continue;
+
+		/*
+		 * On systems with a backplane NUMA topology, compare groups
+		 * of nodes, and move tasks towards the group with the most
+		 * memory accesses. When comparing two nodes at distance
+		 * "hoplimit", only nodes closer by than "hoplimit" are part
+		 * of each group. Skip other nodes.
+		 */
+		if (sched_numa_topology_type == NUMA_BACKPLANE &&
+					dist > maxdist)
+			continue;
+
+		/* Add up the faults from nearby nodes. */
+		if (task)
+			faults = task_faults(p, node);
+		else
+			faults = group_faults(p, node);
+
+		/*
+		 * On systems with a glueless mesh NUMA topology, there are
+		 * no fixed "groups of nodes". Instead, nodes that are not
+		 * directly connected bounce traffic through intermediate
+		 * nodes; a numa_group can occupy any set of nodes.
+		 * The further away a node is, the less the faults count.
+		 * This seems to result in good task placement.
+		 */
+		if (sched_numa_topology_type == NUMA_GLUELESS_MESH) {
+			faults *= (sched_max_numa_distance - dist);
+			faults /= (sched_max_numa_distance - LOCAL_DISTANCE);
+		}
+
+		score += faults;
+	}
+
+	return score;
+}
+
+/*
+ * These return the fraction of accesses done by a particular task, or
+ * task group, on a particular numa node.  The group weight is given a
+ * larger multiplier, in order to group tasks together that are almost
+ * evenly spread out between numa nodes.
+ */
+static inline unsigned long task_weight(struct task_struct *p, int nid,
+					int dist)
+{
+	unsigned long faults, total_faults;
+
+	if (!p->numa_faults)
+		return 0;
+
+	total_faults = p->total_numa_faults;
+
+	if (!total_faults)
+		return 0;
+
+	faults = task_faults(p, nid);
+	faults += score_nearby_nodes(p, nid, dist, true);
+
+	return 1000 * faults / total_faults;
+}
+
+static inline unsigned long group_weight(struct task_struct *p, int nid,
+					 int dist)
+{
+	unsigned long faults, total_faults;
+
+	if (!p->numa_group)
+		return 0;
+
+	total_faults = p->numa_group->total_faults;
+
+	if (!total_faults)
+		return 0;
+
+	faults = group_faults(p, nid);
+	faults += score_nearby_nodes(p, nid, dist, false);
+
+	return 1000 * faults / total_faults;
+}
+
+bool should_numa_migrate_memory(struct task_struct *p, struct page * page,
+				int src_nid, int dst_cpu)
+{
+	struct numa_group *ng = p->numa_group;
+	int dst_nid = cpu_to_node(dst_cpu);
+	int last_cpupid, this_cpupid;
+
+	this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid);
+
+	/*
+	 * Multi-stage node selection is used in conjunction with a periodic
+	 * migration fault to build a temporal task<->page relation. By using
+	 * a two-stage filter we remove short/unlikely relations.
+	 *
+	 * Using P(p) ~ n_p / n_t as per frequentist probability, we can equate
+	 * a task's usage of a particular page (n_p) per total usage of this
+	 * page (n_t) (in a given time-span) to a probability.
+	 *
+	 * Our periodic faults will sample this probability and getting the
+	 * same result twice in a row, given these samples are fully
+	 * independent, is then given by P(n)^2, provided our sample period
+	 * is sufficiently short compared to the usage pattern.
+	 *
+	 * This quadric squishes small probabilities, making it less likely we
+	 * act on an unlikely task<->page relation.
+	 */
+	last_cpupid = page_cpupid_xchg_last(page, this_cpupid);
+	if (!cpupid_pid_unset(last_cpupid) &&
+				cpupid_to_nid(last_cpupid) != dst_nid)
+		return false;
+
+	/* Always allow migrate on private faults */
+	if (cpupid_match_pid(p, last_cpupid))
+		return true;
+
+	/* A shared fault, but p->numa_group has not been set up yet. */
+	if (!ng)
+		return true;
+
+	/*
+	 * Do not migrate if the destination is not a node that
+	 * is actively used by this numa group.
+	 */
+	if (!node_isset(dst_nid, ng->active_nodes))
+		return false;
+
+	/*
+	 * Source is a node that is not actively used by this
+	 * numa group, while the destination is. Migrate.
+	 */
+	if (!node_isset(src_nid, ng->active_nodes))
+		return true;
+
+	/*
+	 * Both source and destination are nodes in active
+	 * use by this numa group. Maximize memory bandwidth
+	 * by migrating from more heavily used groups, to less
+	 * heavily used ones, spreading the load around.
+	 * Use a 1/4 hysteresis to avoid spurious page movement.
+	 */
+	return group_faults(p, dst_nid) < (group_faults(p, src_nid) * 3 / 4);
+}
+
+static unsigned long weighted_cpuload(const int cpu);
+static unsigned long source_load(int cpu, int type);
+static unsigned long target_load(int cpu, int type);
+static unsigned long capacity_of(int cpu);
+static long effective_load(struct task_group *tg, int cpu, long wl, long wg);
+
+/* Cached statistics for all CPUs within a node */
+struct numa_stats {
+	unsigned long nr_running;
+	unsigned long load;
+
+	/* Total compute capacity of CPUs on a node */
+	unsigned long compute_capacity;
+
+	/* Approximate capacity in terms of runnable tasks on a node */
+	unsigned long task_capacity;
+	int has_free_capacity;
+};
+
+/*
+ * XXX borrowed from update_sg_lb_stats
+ */
+static void update_numa_stats(struct numa_stats *ns, int nid)
+{
+	int smt, cpu, cpus = 0;
+	unsigned long capacity;
+
+	memset(ns, 0, sizeof(*ns));
+	for_each_cpu(cpu, cpumask_of_node(nid)) {
+		struct rq *rq = cpu_rq(cpu);
+
+		ns->nr_running += rq->nr_running;
+		ns->load += weighted_cpuload(cpu);
+		ns->compute_capacity += capacity_of(cpu);
+
+		cpus++;
+	}
+
+	/*
+	 * If we raced with hotplug and there are no CPUs left in our mask
+	 * the @ns structure is NULL'ed and task_numa_compare() will
+	 * not find this node attractive.
+	 *
+	 * We'll either bail at !has_free_capacity, or we'll detect a huge
+	 * imbalance and bail there.
+	 */
+	if (!cpus)
+		return;
+
+	/* smt := ceil(cpus / capacity), assumes: 1 < smt_power < 2 */
+	smt = DIV_ROUND_UP(SCHED_CAPACITY_SCALE * cpus, ns->compute_capacity);
+	capacity = cpus / smt; /* cores */
+
+	ns->task_capacity = min_t(unsigned, capacity,
+		DIV_ROUND_CLOSEST(ns->compute_capacity, SCHED_CAPACITY_SCALE));
+	ns->has_free_capacity = (ns->nr_running < ns->task_capacity);
+}
+
+struct task_numa_env {
+	struct task_struct *p;
+
+	int src_cpu, src_nid;
+	int dst_cpu, dst_nid;
+
+	struct numa_stats src_stats, dst_stats;
+
+	int imbalance_pct;
+	int dist;
+
+	struct task_struct *best_task;
+	long best_imp;
+	int best_cpu;
+};
+
+static void task_numa_assign(struct task_numa_env *env,
+			     struct task_struct *p, long imp)
+{
+	if (env->best_task)
+		put_task_struct(env->best_task);
+	if (p)
+		get_task_struct(p);
+
+	env->best_task = p;
+	env->best_imp = imp;
+	env->best_cpu = env->dst_cpu;
+}
+
+static bool load_too_imbalanced(long src_load, long dst_load,
+				struct task_numa_env *env)
+{
+	long src_capacity, dst_capacity;
+	long orig_src_load;
+	long load_a, load_b;
+	long moved_load;
+	long imb;
+
+	/*
+	 * The load is corrected for the CPU capacity available on each node.
+	 *
+	 * src_load        dst_load
+	 * ------------ vs ---------
+	 * src_capacity    dst_capacity
+	 */
+	src_capacity = env->src_stats.compute_capacity;
+	dst_capacity = env->dst_stats.compute_capacity;
+
+	/* We care about the slope of the imbalance, not the direction. */
+	load_a = dst_load;
+	load_b = src_load;
+	if (load_a < load_b)
+		swap(load_a, load_b);
+
+	/* Is the difference below the threshold? */
+	imb = load_a * src_capacity * 100 -
+		load_b * dst_capacity * env->imbalance_pct;
+	if (imb <= 0)
+		return false;
+
+	/*
+	 * The imbalance is above the allowed threshold.
+	 * Allow a move that brings us closer to a balanced situation,
+	 * without moving things past the point of balance.
+	 */
+	orig_src_load = env->src_stats.load;
+
+	/*
+	 * In a task swap, there will be one load moving from src to dst,
+	 * and another moving back. This is the net sum of both moves.
+	 * A simple task move will always have a positive value.
+	 * Allow the move if it brings the system closer to a balanced
+	 * situation, without crossing over the balance point.
+	 */
+	moved_load = orig_src_load - src_load;
+
+	if (moved_load > 0)
+		/* Moving src -> dst. Did we overshoot balance? */
+		return src_load * dst_capacity < dst_load * src_capacity;
+	else
+		/* Moving dst -> src. Did we overshoot balance? */
+		return dst_load * src_capacity < src_load * dst_capacity;
+}
+
+/*
+ * This checks if the overall compute and NUMA accesses of the system would
+ * be improved if the source tasks was migrated to the target dst_cpu taking
+ * into account that it might be best if task running on the dst_cpu should
+ * be exchanged with the source task
+ */
+static void task_numa_compare(struct task_numa_env *env,
+			      long taskimp, long groupimp)
+{
+	struct rq *src_rq = cpu_rq(env->src_cpu);
+	struct rq *dst_rq = cpu_rq(env->dst_cpu);
+	struct task_struct *cur;
+	long src_load, dst_load;
+	long load;
+	long imp = env->p->numa_group ? groupimp : taskimp;
+	long moveimp = imp;
+	int dist = env->dist;
+
+	rcu_read_lock();
+
+	raw_spin_lock_irq(&dst_rq->lock);
+	cur = dst_rq->curr;
+	/*
+	 * No need to move the exiting task, and this ensures that ->curr
+	 * wasn't reaped and thus get_task_struct() in task_numa_assign()
+	 * is safe under RCU read lock.
+	 * Note that rcu_read_lock() itself can't protect from the final
+	 * put_task_struct() after the last schedule().
+	 */
+	if ((cur->flags & PF_EXITING) || is_idle_task(cur))
+		cur = NULL;
+	raw_spin_unlock_irq(&dst_rq->lock);
+
+	/*
+	 * Because we have preemption enabled we can get migrated around and
+	 * end try selecting ourselves (current == env->p) as a swap candidate.
+	 */
+	if (cur == env->p)
+		goto unlock;
+
+	/*
+	 * "imp" is the fault differential for the source task between the
+	 * source and destination node. Calculate the total differential for
+	 * the source task and potential destination task. The more negative
+	 * the value is, the more rmeote accesses that would be expected to
+	 * be incurred if the tasks were swapped.
+	 */
+	if (cur) {
+		/* Skip this swap candidate if cannot move to the source cpu */
+		if (!cpumask_test_cpu(env->src_cpu, tsk_cpus_allowed(cur)))
+			goto unlock;
+
+		/*
+		 * If dst and source tasks are in the same NUMA group, or not
+		 * in any group then look only at task weights.
+		 */
+		if (cur->numa_group == env->p->numa_group) {
+			imp = taskimp + task_weight(cur, env->src_nid, dist) -
+			      task_weight(cur, env->dst_nid, dist);
+			/*
+			 * Add some hysteresis to prevent swapping the
+			 * tasks within a group over tiny differences.
+			 */
+			if (cur->numa_group)
+				imp -= imp/16;
+		} else {
+			/*
+			 * Compare the group weights. If a task is all by
+			 * itself (not part of a group), use the task weight
+			 * instead.
+			 */
+			if (cur->numa_group)
+				imp += group_weight(cur, env->src_nid, dist) -
+				       group_weight(cur, env->dst_nid, dist);
+			else
+				imp += task_weight(cur, env->src_nid, dist) -
+				       task_weight(cur, env->dst_nid, dist);
+		}
+	}
+
+	if (imp <= env->best_imp && moveimp <= env->best_imp)
+		goto unlock;
+
+	if (!cur) {
+		/* Is there capacity at our destination? */
+		if (env->src_stats.nr_running <= env->src_stats.task_capacity &&
+		    !env->dst_stats.has_free_capacity)
+			goto unlock;
+
+		goto balance;
+	}
+
+	/* Balance doesn't matter much if we're running a task per cpu */
+	if (imp > env->best_imp && src_rq->nr_running == 1 &&
+			dst_rq->nr_running == 1)
+		goto assign;
+
+	/*
+	 * In the overloaded case, try and keep the load balanced.
+	 */
+balance:
+	load = task_h_load(env->p);
+	dst_load = env->dst_stats.load + load;
+	src_load = env->src_stats.load - load;
+
+	if (moveimp > imp && moveimp > env->best_imp) {
+		/*
+		 * If the improvement from just moving env->p direction is
+		 * better than swapping tasks around, check if a move is
+		 * possible. Store a slightly smaller score than moveimp,
+		 * so an actually idle CPU will win.
+		 */
+		if (!load_too_imbalanced(src_load, dst_load, env)) {
+			imp = moveimp - 1;
+			cur = NULL;
+			goto assign;
+		}
+	}
+
+	if (imp <= env->best_imp)
+		goto unlock;
+
+	if (cur) {
+		load = task_h_load(cur);
+		dst_load -= load;
+		src_load += load;
+	}
+
+	if (load_too_imbalanced(src_load, dst_load, env))
+		goto unlock;
+
+	/*
+	 * One idle CPU per node is evaluated for a task numa move.
+	 * Call select_idle_sibling to maybe find a better one.
+	 */
+	if (!cur)
+		env->dst_cpu = select_idle_sibling(env->p, env->dst_cpu);
+
+assign:
+	task_numa_assign(env, cur, imp);
+unlock:
+	rcu_read_unlock();
+}
+
+static void task_numa_find_cpu(struct task_numa_env *env,
+				long taskimp, long groupimp)
+{
+	int cpu;
+
+	for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) {
+		/* Skip this CPU if the source task cannot migrate */
+		if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(env->p)))
+			continue;
+
+		env->dst_cpu = cpu;
+		task_numa_compare(env, taskimp, groupimp);
+	}
+}
+
+static int task_numa_migrate(struct task_struct *p)
+{
+	struct task_numa_env env = {
+		.p = p,
+
+		.src_cpu = task_cpu(p),
+		.src_nid = task_node(p),
+
+		.imbalance_pct = 112,
+
+		.best_task = NULL,
+		.best_imp = 0,
+		.best_cpu = -1
+	};
+	struct sched_domain *sd;
+	unsigned long taskweight, groupweight;
+	int nid, ret, dist;
+	long taskimp, groupimp;
+
+	/*
+	 * Pick the lowest SD_NUMA domain, as that would have the smallest
+	 * imbalance and would be the first to start moving tasks about.
+	 *
+	 * And we want to avoid any moving of tasks about, as that would create
+	 * random movement of tasks -- counter the numa conditions we're trying
+	 * to satisfy here.
+	 */
+	rcu_read_lock();
+	sd = rcu_dereference(per_cpu(sd_numa, env.src_cpu));
+	if (sd)
+		env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2;
+	rcu_read_unlock();
+
+	/*
+	 * Cpusets can break the scheduler domain tree into smaller
+	 * balance domains, some of which do not cross NUMA boundaries.
+	 * Tasks that are "trapped" in such domains cannot be migrated
+	 * elsewhere, so there is no point in (re)trying.
+	 */
+	if (unlikely(!sd)) {
+		p->numa_preferred_nid = task_node(p);
+		return -EINVAL;
+	}
+
+	env.dst_nid = p->numa_preferred_nid;
+	dist = env.dist = node_distance(env.src_nid, env.dst_nid);
+	taskweight = task_weight(p, env.src_nid, dist);
+	groupweight = group_weight(p, env.src_nid, dist);
+	update_numa_stats(&env.src_stats, env.src_nid);
+	taskimp = task_weight(p, env.dst_nid, dist) - taskweight;
+	groupimp = group_weight(p, env.dst_nid, dist) - groupweight;
+	update_numa_stats(&env.dst_stats, env.dst_nid);
+
+	/* Try to find a spot on the preferred nid. */
+	task_numa_find_cpu(&env, taskimp, groupimp);
+
+	/*
+	 * Look at other nodes in these cases:
+	 * - there is no space available on the preferred_nid
+	 * - the task is part of a numa_group that is interleaved across
+	 *   multiple NUMA nodes; in order to better consolidate the group,
+	 *   we need to check other locations.
+	 */
+	if (env.best_cpu == -1 || (p->numa_group &&
+			nodes_weight(p->numa_group->active_nodes) > 1)) {
+		for_each_online_node(nid) {
+			if (nid == env.src_nid || nid == p->numa_preferred_nid)
+				continue;
+
+			dist = node_distance(env.src_nid, env.dst_nid);
+			if (sched_numa_topology_type == NUMA_BACKPLANE &&
+						dist != env.dist) {
+				taskweight = task_weight(p, env.src_nid, dist);
+				groupweight = group_weight(p, env.src_nid, dist);
+			}
+
+			/* Only consider nodes where both task and groups benefit */
+			taskimp = task_weight(p, nid, dist) - taskweight;
+			groupimp = group_weight(p, nid, dist) - groupweight;
+			if (taskimp < 0 && groupimp < 0)
+				continue;
+
+			env.dist = dist;
+			env.dst_nid = nid;
+			update_numa_stats(&env.dst_stats, env.dst_nid);
+			task_numa_find_cpu(&env, taskimp, groupimp);
+		}
+	}
+
+	/*
+	 * If the task is part of a workload that spans multiple NUMA nodes,
+	 * and is migrating into one of the workload's active nodes, remember
+	 * this node as the task's preferred numa node, so the workload can
+	 * settle down.
+	 * A task that migrated to a second choice node will be better off
+	 * trying for a better one later. Do not set the preferred node here.
+	 */
+	if (p->numa_group) {
+		if (env.best_cpu == -1)
+			nid = env.src_nid;
+		else
+			nid = env.dst_nid;
+
+		if (node_isset(nid, p->numa_group->active_nodes))
+			sched_setnuma(p, env.dst_nid);
+	}
+
+	/* No better CPU than the current one was found. */
+	if (env.best_cpu == -1)
+		return -EAGAIN;
+
+	/*
+	 * Reset the scan period if the task is being rescheduled on an
+	 * alternative node to recheck if the tasks is now properly placed.
+	 */
+	p->numa_scan_period = task_scan_min(p);
+
+	if (env.best_task == NULL) {
+		ret = migrate_task_to(p, env.best_cpu);
+		if (ret != 0)
+			trace_sched_stick_numa(p, env.src_cpu, env.best_cpu);
+		return ret;
+	}
+
+	ret = migrate_swap(p, env.best_task);
+	if (ret != 0)
+		trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task));
+	put_task_struct(env.best_task);
+	return ret;
+}
+
+/* Attempt to migrate a task to a CPU on the preferred node. */
+static void numa_migrate_preferred(struct task_struct *p)
+{
+	unsigned long interval = HZ;
+
+	/* This task has no NUMA fault statistics yet */
+	if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults))
+		return;
+
+	/* Periodically retry migrating the task to the preferred node */
+	interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16);
+	p->numa_migrate_retry = jiffies + interval;
+
+	/* Success if task is already running on preferred CPU */
+	if (task_node(p) == p->numa_preferred_nid)
+		return;
+
+	/* Otherwise, try migrate to a CPU on the preferred node */
+	task_numa_migrate(p);
+}
+
+/*
+ * Find the nodes on which the workload is actively running. We do this by
+ * tracking the nodes from which NUMA hinting faults are triggered. This can
+ * be different from the set of nodes where the workload's memory is currently
+ * located.
+ *
+ * The bitmask is used to make smarter decisions on when to do NUMA page
+ * migrations, To prevent flip-flopping, and excessive page migrations, nodes
+ * are added when they cause over 6/16 of the maximum number of faults, but
+ * only removed when they drop below 3/16.
+ */
+static void update_numa_active_node_mask(struct numa_group *numa_group)
+{
+	unsigned long faults, max_faults = 0;
+	int nid;
+
+	for_each_online_node(nid) {
+		faults = group_faults_cpu(numa_group, nid);
+		if (faults > max_faults)
+			max_faults = faults;
+	}
+
+	for_each_online_node(nid) {
+		faults = group_faults_cpu(numa_group, nid);
+		if (!node_isset(nid, numa_group->active_nodes)) {
+			if (faults > max_faults * 6 / 16)
+				node_set(nid, numa_group->active_nodes);
+		} else if (faults < max_faults * 3 / 16)
+			node_clear(nid, numa_group->active_nodes);
+	}
+}
+
+/*
+ * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS
+ * increments. The more local the fault statistics are, the higher the scan
+ * period will be for the next scan window. If local/(local+remote) ratio is
+ * below NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS)
+ * the scan period will decrease. Aim for 70% local accesses.
+ */
+#define NUMA_PERIOD_SLOTS 10
+#define NUMA_PERIOD_THRESHOLD 7
+
+/*
+ * Increase the scan period (slow down scanning) if the majority of
+ * our memory is already on our local node, or if the majority of
+ * the page accesses are shared with other processes.
+ * Otherwise, decrease the scan period.
+ */
+static void update_task_scan_period(struct task_struct *p,
+			unsigned long shared, unsigned long private)
+{
+	unsigned int period_slot;
+	int ratio;
+	int diff;
+
+	unsigned long remote = p->numa_faults_locality[0];
+	unsigned long local = p->numa_faults_locality[1];
+
+	/*
+	 * If there were no record hinting faults then either the task is
+	 * completely idle or all activity is areas that are not of interest
+	 * to automatic numa balancing. Related to that, if there were failed
+	 * migration then it implies we are migrating too quickly or the local
+	 * node is overloaded. In either case, scan slower
+	 */
+	if (local + shared == 0 || p->numa_faults_locality[2]) {
+		p->numa_scan_period = min(p->numa_scan_period_max,
+			p->numa_scan_period << 1);
+
+		p->mm->numa_next_scan = jiffies +
+			msecs_to_jiffies(p->numa_scan_period);
+
+		return;
+	}
+
+	/*
+	 * Prepare to scale scan period relative to the current period.
+	 *	 == NUMA_PERIOD_THRESHOLD scan period stays the same
+	 *       <  NUMA_PERIOD_THRESHOLD scan period decreases (scan faster)
+	 *	 >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower)
+	 */
+	period_slot = DIV_ROUND_UP(p->numa_scan_period, NUMA_PERIOD_SLOTS);
+	ratio = (local * NUMA_PERIOD_SLOTS) / (local + remote);
+	if (ratio >= NUMA_PERIOD_THRESHOLD) {
+		int slot = ratio - NUMA_PERIOD_THRESHOLD;
+		if (!slot)
+			slot = 1;
+		diff = slot * period_slot;
+	} else {
+		diff = -(NUMA_PERIOD_THRESHOLD - ratio) * period_slot;
+
+		/*
+		 * Scale scan rate increases based on sharing. There is an
+		 * inverse relationship between the degree of sharing and
+		 * the adjustment made to the scanning period. Broadly
+		 * speaking the intent is that there is little point
+		 * scanning faster if shared accesses dominate as it may
+		 * simply bounce migrations uselessly
+		 */
+		ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + shared + 1));
+		diff = (diff * ratio) / NUMA_PERIOD_SLOTS;
+	}
+
+	p->numa_scan_period = clamp(p->numa_scan_period + diff,
+			task_scan_min(p), task_scan_max(p));
+	memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality));
+}
+
+/*
+ * Get the fraction of time the task has been running since the last
+ * NUMA placement cycle. The scheduler keeps similar statistics, but
+ * decays those on a 32ms period, which is orders of magnitude off
+ * from the dozens-of-seconds NUMA balancing period. Use the scheduler
+ * stats only if the task is so new there are no NUMA statistics yet.
+ */
+static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period)
+{
+	u64 runtime, delta, now;
+	/* Use the start of this time slice to avoid calculations. */
+	now = p->se.exec_start;
+	runtime = p->se.sum_exec_runtime;
+
+	if (p->last_task_numa_placement) {
+		delta = runtime - p->last_sum_exec_runtime;
+		*period = now - p->last_task_numa_placement;
+	} else {
+		delta = p->se.avg.runnable_avg_sum;
+		*period = p->se.avg.avg_period;
+	}
+
+	p->last_sum_exec_runtime = runtime;
+	p->last_task_numa_placement = now;
+
+	return delta;
+}
+
+/*
+ * Determine the preferred nid for a task in a numa_group. This needs to
+ * be done in a way that produces consistent results with group_weight,
+ * otherwise workloads might not converge.
+ */
+static int preferred_group_nid(struct task_struct *p, int nid)
+{
+	nodemask_t nodes;
+	int dist;
+
+	/* Direct connections between all NUMA nodes. */
+	if (sched_numa_topology_type == NUMA_DIRECT)
+		return nid;
+
+	/*
+	 * On a system with glueless mesh NUMA topology, group_weight
+	 * scores nodes according to the number of NUMA hinting faults on
+	 * both the node itself, and on nearby nodes.
+	 */
+	if (sched_numa_topology_type == NUMA_GLUELESS_MESH) {
+		unsigned long score, max_score = 0;
+		int node, max_node = nid;
+
+		dist = sched_max_numa_distance;
+
+		for_each_online_node(node) {
+			score = group_weight(p, node, dist);
+			if (score > max_score) {
+				max_score = score;
+				max_node = node;
+			}
+		}
+		return max_node;
+	}
+
+	/*
+	 * Finding the preferred nid in a system with NUMA backplane
+	 * interconnect topology is more involved. The goal is to locate
+	 * tasks from numa_groups near each other in the system, and
+	 * untangle workloads from different sides of the system. This requires
+	 * searching down the hierarchy of node groups, recursively searching
+	 * inside the highest scoring group of nodes. The nodemask tricks
+	 * keep the complexity of the search down.
+	 */
+	nodes = node_online_map;
+	for (dist = sched_max_numa_distance; dist > LOCAL_DISTANCE; dist--) {
+		unsigned long max_faults = 0;
+		nodemask_t max_group = NODE_MASK_NONE;
+		int a, b;
+
+		/* Are there nodes at this distance from each other? */
+		if (!find_numa_distance(dist))
+			continue;
+
+		for_each_node_mask(a, nodes) {
+			unsigned long faults = 0;
+			nodemask_t this_group;
+			nodes_clear(this_group);
+
+			/* Sum group's NUMA faults; includes a==b case. */
+			for_each_node_mask(b, nodes) {
+				if (node_distance(a, b) < dist) {
+					faults += group_faults(p, b);
+					node_set(b, this_group);
+					node_clear(b, nodes);
+				}
+			}
+
+			/* Remember the top group. */
+			if (faults > max_faults) {
+				max_faults = faults;
+				max_group = this_group;
+				/*
+				 * subtle: at the smallest distance there is
+				 * just one node left in each "group", the
+				 * winner is the preferred nid.
+				 */
+				nid = a;
+			}
+		}
+		/* Next round, evaluate the nodes within max_group. */
+		if (!max_faults)
+			break;
+		nodes = max_group;
+	}
+	return nid;
+}
+
+static void task_numa_placement(struct task_struct *p)
+{
+	int seq, nid, max_nid = -1, max_group_nid = -1;
+	unsigned long max_faults = 0, max_group_faults = 0;
+	unsigned long fault_types[2] = { 0, 0 };
+	unsigned long total_faults;
+	u64 runtime, period;
+	spinlock_t *group_lock = NULL;
+
+	seq = ACCESS_ONCE(p->mm->numa_scan_seq);
+	if (p->numa_scan_seq == seq)
+		return;
+	p->numa_scan_seq = seq;
+	p->numa_scan_period_max = task_scan_max(p);
+
+	total_faults = p->numa_faults_locality[0] +
+		       p->numa_faults_locality[1];
+	runtime = numa_get_avg_runtime(p, &period);
+
+	/* If the task is part of a group prevent parallel updates to group stats */
+	if (p->numa_group) {
+		group_lock = &p->numa_group->lock;
+		spin_lock_irq(group_lock);
+	}
+
+	/* Find the node with the highest number of faults */
+	for_each_online_node(nid) {
+		/* Keep track of the offsets in numa_faults array */
+		int mem_idx, membuf_idx, cpu_idx, cpubuf_idx;
+		unsigned long faults = 0, group_faults = 0;
+		int priv;
+
+		for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) {
+			long diff, f_diff, f_weight;
+
+			mem_idx = task_faults_idx(NUMA_MEM, nid, priv);
+			membuf_idx = task_faults_idx(NUMA_MEMBUF, nid, priv);
+			cpu_idx = task_faults_idx(NUMA_CPU, nid, priv);
+			cpubuf_idx = task_faults_idx(NUMA_CPUBUF, nid, priv);
+
+			/* Decay existing window, copy faults since last scan */
+			diff = p->numa_faults[membuf_idx] - p->numa_faults[mem_idx] / 2;
+			fault_types[priv] += p->numa_faults[membuf_idx];
+			p->numa_faults[membuf_idx] = 0;
+
+			/*
+			 * Normalize the faults_from, so all tasks in a group
+			 * count according to CPU use, instead of by the raw
+			 * number of faults. Tasks with little runtime have
+			 * little over-all impact on throughput, and thus their
+			 * faults are less important.
+			 */
+			f_weight = div64_u64(runtime << 16, period + 1);
+			f_weight = (f_weight * p->numa_faults[cpubuf_idx]) /
+				   (total_faults + 1);
+			f_diff = f_weight - p->numa_faults[cpu_idx] / 2;
+			p->numa_faults[cpubuf_idx] = 0;
+
+			p->numa_faults[mem_idx] += diff;
+			p->numa_faults[cpu_idx] += f_diff;
+			faults += p->numa_faults[mem_idx];
+			p->total_numa_faults += diff;
+			if (p->numa_group) {
+				/*
+				 * safe because we can only change our own group
+				 *
+				 * mem_idx represents the offset for a given
+				 * nid and priv in a specific region because it
+				 * is at the beginning of the numa_faults array.
+				 */
+				p->numa_group->faults[mem_idx] += diff;
+				p->numa_group->faults_cpu[mem_idx] += f_diff;
+				p->numa_group->total_faults += diff;
+				group_faults += p->numa_group->faults[mem_idx];
+			}
+		}
+
+		if (faults > max_faults) {
+			max_faults = faults;
+			max_nid = nid;
+		}
+
+		if (group_faults > max_group_faults) {
+			max_group_faults = group_faults;
+			max_group_nid = nid;
+		}
+	}
+
+	update_task_scan_period(p, fault_types[0], fault_types[1]);
+
+	if (p->numa_group) {
+		update_numa_active_node_mask(p->numa_group);
+		spin_unlock_irq(group_lock);
+		max_nid = preferred_group_nid(p, max_group_nid);
+	}
+
+	if (max_faults) {
+		/* Set the new preferred node */
+		if (max_nid != p->numa_preferred_nid)
+			sched_setnuma(p, max_nid);
+
+		if (task_node(p) != p->numa_preferred_nid)
+			numa_migrate_preferred(p);
+	}
+}
+
+static inline int get_numa_group(struct numa_group *grp)
+{
+	return atomic_inc_not_zero(&grp->refcount);
+}
+
+static inline void put_numa_group(struct numa_group *grp)
+{
+	if (atomic_dec_and_test(&grp->refcount))
+		kfree_rcu(grp, rcu);
+}
+
+static void task_numa_group(struct task_struct *p, int cpupid, int flags,
+			int *priv)
+{
+	struct numa_group *grp, *my_grp;
+	struct task_struct *tsk;
+	bool join = false;
+	int cpu = cpupid_to_cpu(cpupid);
+	int i;
+
+	if (unlikely(!p->numa_group)) {
+		unsigned int size = sizeof(struct numa_group) +
+				    4*nr_node_ids*sizeof(unsigned long);
+
+		grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
+		if (!grp)
+			return;
+
+		atomic_set(&grp->refcount, 1);
+		spin_lock_init(&grp->lock);
+		grp->gid = p->pid;
+		/* Second half of the array tracks nids where faults happen */
+		grp->faults_cpu = grp->faults + NR_NUMA_HINT_FAULT_TYPES *
+						nr_node_ids;
+
+		node_set(task_node(current), grp->active_nodes);
+
+		for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
+			grp->faults[i] = p->numa_faults[i];
+
+		grp->total_faults = p->total_numa_faults;
+
+		grp->nr_tasks++;
+		rcu_assign_pointer(p->numa_group, grp);
+	}
+
+	rcu_read_lock();
+	tsk = ACCESS_ONCE(cpu_rq(cpu)->curr);
+
+	if (!cpupid_match_pid(tsk, cpupid))
+		goto no_join;
+
+	grp = rcu_dereference(tsk->numa_group);
+	if (!grp)
+		goto no_join;
+
+	my_grp = p->numa_group;
+	if (grp == my_grp)
+		goto no_join;
+
+	/*
+	 * Only join the other group if its bigger; if we're the bigger group,
+	 * the other task will join us.
+	 */
+	if (my_grp->nr_tasks > grp->nr_tasks)
+		goto no_join;
+
+	/*
+	 * Tie-break on the grp address.
+	 */
+	if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp)
+		goto no_join;
+
+	/* Always join threads in the same process. */
+	if (tsk->mm == current->mm)
+		join = true;
+
+	/* Simple filter to avoid false positives due to PID collisions */
+	if (flags & TNF_SHARED)
+		join = true;
+
+	/* Update priv based on whether false sharing was detected */
+	*priv = !join;
+
+	if (join && !get_numa_group(grp))
+		goto no_join;
+
+	rcu_read_unlock();
+
+	if (!join)
+		return;
+
+	BUG_ON(irqs_disabled());
+	double_lock_irq(&my_grp->lock, &grp->lock);
+
+	for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
+		my_grp->faults[i] -= p->numa_faults[i];
+		grp->faults[i] += p->numa_faults[i];
+	}
+	my_grp->total_faults -= p->total_numa_faults;
+	grp->total_faults += p->total_numa_faults;
+
+	my_grp->nr_tasks--;
+	grp->nr_tasks++;
+
+	spin_unlock(&my_grp->lock);
+	spin_unlock_irq(&grp->lock);
+
+	rcu_assign_pointer(p->numa_group, grp);
+
+	put_numa_group(my_grp);
+	return;
+
+no_join:
+	rcu_read_unlock();
+	return;
+}
+
+void task_numa_free(struct task_struct *p)
+{
+	struct numa_group *grp = p->numa_group;
+	void *numa_faults = p->numa_faults;
+	unsigned long flags;
+	int i;
+
+	if (grp) {
+		spin_lock_irqsave(&grp->lock, flags);
+		for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
+			grp->faults[i] -= p->numa_faults[i];
+		grp->total_faults -= p->total_numa_faults;
+
+		grp->nr_tasks--;
+		spin_unlock_irqrestore(&grp->lock, flags);
+		RCU_INIT_POINTER(p->numa_group, NULL);
+		put_numa_group(grp);
+	}
+
+	p->numa_faults = NULL;
+	kfree(numa_faults);
+}
+
+/*
+ * Got a PROT_NONE fault for a page on @node.
+ */
+void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
+{
+	struct task_struct *p = current;
+	bool migrated = flags & TNF_MIGRATED;
+	int cpu_node = task_node(current);
+	int local = !!(flags & TNF_FAULT_LOCAL);
+	int priv;
+
+	if (!numabalancing_enabled)
+		return;
+
+	/* for example, ksmd faulting in a user's mm */
+	if (!p->mm)
+		return;
+
+	/* Allocate buffer to track faults on a per-node basis */
+	if (unlikely(!p->numa_faults)) {
+		int size = sizeof(*p->numa_faults) *
+			   NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids;
+
+		p->numa_faults = kzalloc(size, GFP_KERNEL|__GFP_NOWARN);
+		if (!p->numa_faults)
+			return;
+
+		p->total_numa_faults = 0;
+		memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality));
+	}
+
+	/*
+	 * First accesses are treated as private, otherwise consider accesses
+	 * to be private if the accessing pid has not changed
+	 */
+	if (unlikely(last_cpupid == (-1 & LAST_CPUPID_MASK))) {
+		priv = 1;
+	} else {
+		priv = cpupid_match_pid(p, last_cpupid);
+		if (!priv && !(flags & TNF_NO_GROUP))
+			task_numa_group(p, last_cpupid, flags, &priv);
+	}
+
+	/*
+	 * If a workload spans multiple NUMA nodes, a shared fault that
+	 * occurs wholly within the set of nodes that the workload is
+	 * actively using should be counted as local. This allows the
+	 * scan rate to slow down when a workload has settled down.
+	 */
+	if (!priv && !local && p->numa_group &&
+			node_isset(cpu_node, p->numa_group->active_nodes) &&
+			node_isset(mem_node, p->numa_group->active_nodes))
+		local = 1;
+
+	task_numa_placement(p);
+
+	/*
+	 * Retry task to preferred node migration periodically, in case it
+	 * case it previously failed, or the scheduler moved us.
+	 */
+	if (time_after(jiffies, p->numa_migrate_retry))
+		numa_migrate_preferred(p);
+
+	if (migrated)
+		p->numa_pages_migrated += pages;
+	if (flags & TNF_MIGRATE_FAIL)
+		p->numa_faults_locality[2] += pages;
+
+	p->numa_faults[task_faults_idx(NUMA_MEMBUF, mem_node, priv)] += pages;
+	p->numa_faults[task_faults_idx(NUMA_CPUBUF, cpu_node, priv)] += pages;
+	p->numa_faults_locality[local] += pages;
+}
+
+static void reset_ptenuma_scan(struct task_struct *p)
+{
+	ACCESS_ONCE(p->mm->numa_scan_seq)++;
+	p->mm->numa_scan_offset = 0;
+}
+
+/*
+ * The expensive part of numa migration is done from task_work context.
+ * Triggered from task_tick_numa().
+ */
+void task_numa_work(struct callback_head *work)
+{
+	unsigned long migrate, next_scan, now = jiffies;
+	struct task_struct *p = current;
+	struct mm_struct *mm = p->mm;
+	struct vm_area_struct *vma;
+	unsigned long start, end;
+	unsigned long nr_pte_updates = 0;
+	long pages;
+
+	WARN_ON_ONCE(p != container_of(work, struct task_struct, numa_work));
+
+	work->next = work; /* protect against double add */
+	/*
+	 * Who cares about NUMA placement when they're dying.
+	 *
+	 * NOTE: make sure not to dereference p->mm before this check,
+	 * exit_task_work() happens _after_ exit_mm() so we could be called
+	 * without p->mm even though we still had it when we enqueued this
+	 * work.
+	 */
+	if (p->flags & PF_EXITING)
+		return;
+
+	if (!mm->numa_next_scan) {
+		mm->numa_next_scan = now +
+			msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
+	}
+
+	/*
+	 * Enforce maximal scan/migration frequency..
+	 */
+	migrate = mm->numa_next_scan;
+	if (time_before(now, migrate))
+		return;
+
+	if (p->numa_scan_period == 0) {
+		p->numa_scan_period_max = task_scan_max(p);
+		p->numa_scan_period = task_scan_min(p);
+	}
+
+	next_scan = now + msecs_to_jiffies(p->numa_scan_period);
+	if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate)
+		return;
+
+	/*
+	 * Delay this task enough that another task of this mm will likely win
+	 * the next time around.
+	 */
+	p->node_stamp += 2 * TICK_NSEC;
+
+	start = mm->numa_scan_offset;
+	pages = sysctl_numa_balancing_scan_size;
+	pages <<= 20 - PAGE_SHIFT; /* MB in pages */
+	if (!pages)
+		return;
+
+	down_read(&mm->mmap_sem);
+	vma = find_vma(mm, start);
+	if (!vma) {
+		reset_ptenuma_scan(p);
+		start = 0;
+		vma = mm->mmap;
+	}
+	for (; vma; vma = vma->vm_next) {
+		if (!vma_migratable(vma) || !vma_policy_mof(vma) ||
+			is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_MIXEDMAP)) {
+			continue;
+		}
+
+		/*
+		 * Shared library pages mapped by multiple processes are not
+		 * migrated as it is expected they are cache replicated. Avoid
+		 * hinting faults in read-only file-backed mappings or the vdso
+		 * as migrating the pages will be of marginal benefit.
+		 */
+		if (!vma->vm_mm ||
+		    (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ)))
+			continue;
+
+		/*
+		 * Skip inaccessible VMAs to avoid any confusion between
+		 * PROT_NONE and NUMA hinting ptes
+		 */
+		if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
+			continue;
+
+		do {
+			start = max(start, vma->vm_start);
+			end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE);
+			end = min(end, vma->vm_end);
+			nr_pte_updates += change_prot_numa(vma, start, end);
+
+			/*
+			 * Scan sysctl_numa_balancing_scan_size but ensure that
+			 * at least one PTE is updated so that unused virtual
+			 * address space is quickly skipped.
+			 */
+			if (nr_pte_updates)
+				pages -= (end - start) >> PAGE_SHIFT;
+
+			start = end;
+			if (pages <= 0)
+				goto out;
+
+			cond_resched();
+		} while (end != vma->vm_end);
+	}
+
+out:
+	/*
+	 * It is possible to reach the end of the VMA list but the last few
+	 * VMAs are not guaranteed to the vma_migratable. If they are not, we
+	 * would find the !migratable VMA on the next scan but not reset the
+	 * scanner to the start so check it now.
+	 */
+	if (vma)
+		mm->numa_scan_offset = start;
+	else
+		reset_ptenuma_scan(p);
+	up_read(&mm->mmap_sem);
+}
+
+/*
+ * Drive the periodic memory faults..
+ */
+void task_tick_numa(struct rq *rq, struct task_struct *curr)
+{
+	struct callback_head *work = &curr->numa_work;
+	u64 period, now;
+
+	/*
+	 * We don't care about NUMA placement if we don't have memory.
+	 */
+	if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work)
+		return;
+
+	/*
+	 * Using runtime rather than walltime has the dual advantage that
+	 * we (mostly) drive the selection from busy threads and that the
+	 * task needs to have done some actual work before we bother with
+	 * NUMA placement.
+	 */
+	now = curr->se.sum_exec_runtime;
+	period = (u64)curr->numa_scan_period * NSEC_PER_MSEC;
+
+	if (now - curr->node_stamp > period) {
+		if (!curr->node_stamp)
+			curr->numa_scan_period = task_scan_min(curr);
+		curr->node_stamp += period;
+
+		if (!time_before(jiffies, curr->mm->numa_next_scan)) {
+			init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */
+			task_work_add(curr, work, true);
+		}
+	}
+}
+#else
+static void task_tick_numa(struct rq *rq, struct task_struct *curr)
+{
+}
+
+static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p)
+{
+}
+
+static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p)
+{
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
+static void
+account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	update_load_add(&cfs_rq->load, se->load.weight);
+	if (!parent_entity(se))
+		update_load_add(&rq_of(cfs_rq)->load, se->load.weight);
+#ifdef CONFIG_SMP
+	if (entity_is_task(se)) {
+		struct rq *rq = rq_of(cfs_rq);
+
+		account_numa_enqueue(rq, task_of(se));
+		list_add(&se->group_node, &rq->cfs_tasks);
+	}
+#endif
+	cfs_rq->nr_running++;
+}
+
+static void
+account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	update_load_sub(&cfs_rq->load, se->load.weight);
+	if (!parent_entity(se))
+		update_load_sub(&rq_of(cfs_rq)->load, se->load.weight);
+	if (entity_is_task(se)) {
+		account_numa_dequeue(rq_of(cfs_rq), task_of(se));
+		list_del_init(&se->group_node);
+	}
+	cfs_rq->nr_running--;
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+# ifdef CONFIG_SMP
+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_long_read(&tg->load_avg);
+	tg_weight -= cfs_rq->tg_load_contrib;
+	tg_weight += cfs_rq->load.weight;
+
+	return tg_weight;
+}
+
+static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
+{
+	long tg_weight, load, shares;
+
+	tg_weight = calc_tg_weight(tg, cfs_rq);
+	load = cfs_rq->load.weight;
+
+	shares = (tg->shares * load);
+	if (tg_weight)
+		shares /= tg_weight;
+
+	if (shares < MIN_SHARES)
+		shares = MIN_SHARES;
+	if (shares > tg->shares)
+		shares = tg->shares;
+
+	return shares;
+}
+# else /* CONFIG_SMP */
+static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
+{
+	return tg->shares;
+}
+# endif /* CONFIG_SMP */
+static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
+			    unsigned long weight)
+{
+	if (se->on_rq) {
+		/* commit outstanding execution time */
+		if (cfs_rq->curr == se)
+			update_curr(cfs_rq);
+		account_entity_dequeue(cfs_rq, se);
+	}
+
+	update_load_set(&se->load, weight);
+
+	if (se->on_rq)
+		account_entity_enqueue(cfs_rq, se);
+}
+
+static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
+
+static void update_cfs_shares(struct cfs_rq *cfs_rq)
+{
+	struct task_group *tg;
+	struct sched_entity *se;
+	long shares;
+
+	tg = cfs_rq->tg;
+	se = tg->se[cpu_of(rq_of(cfs_rq))];
+	if (!se || throttled_hierarchy(cfs_rq))
+		return;
+#ifndef CONFIG_SMP
+	if (likely(se->load.weight == tg->shares))
+		return;
+#endif
+	shares = calc_cfs_shares(cfs_rq, tg);
+
+	reweight_entity(cfs_rq_of(se), se, shares);
+}
+#else /* CONFIG_FAIR_GROUP_SCHED */
+static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
+{
+}
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
+#ifdef CONFIG_SMP
+/*
+ * We choose a half-life close to 1 scheduling period.
+ * Note: The tables below are dependent on this value.
+ */
+#define LOAD_AVG_PERIOD 32
+#define LOAD_AVG_MAX 47742 /* maximum possible load avg */
+#define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_MAX_AVG */
+
+/* Precomputed fixed inverse multiplies for multiplication by y^n */
+static const u32 runnable_avg_yN_inv[] = {
+	0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6,
+	0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85,
+	0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581,
+	0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9,
+	0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80,
+	0x85aac367, 0x82cd8698,
+};
+
+/*
+ * Precomputed \Sum y^k { 1<=k<=n }.  These are floor(true_value) to prevent
+ * over-estimates when re-combining.
+ */
+static const u32 runnable_avg_yN_sum[] = {
+	    0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103,
+	 9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082,
+	17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371,
+};
+
+/*
+ * Approximate:
+ *   val * y^n,    where y^32 ~= 0.5 (~1 scheduling period)
+ */
+static __always_inline u64 decay_load(u64 val, u64 n)
+{
+	unsigned int local_n;
+
+	if (!n)
+		return val;
+	else if (unlikely(n > LOAD_AVG_PERIOD * 63))
+		return 0;
+
+	/* after bounds checking we can collapse to 32-bit */
+	local_n = n;
+
+	/*
+	 * As y^PERIOD = 1/2, we can combine
+	 *    y^n = 1/2^(n/PERIOD) * y^(n%PERIOD)
+	 * With a look-up table which covers y^n (n<PERIOD)
+	 *
+	 * To achieve constant time decay_load.
+	 */
+	if (unlikely(local_n >= LOAD_AVG_PERIOD)) {
+		val >>= local_n / LOAD_AVG_PERIOD;
+		local_n %= LOAD_AVG_PERIOD;
+	}
+
+	val *= runnable_avg_yN_inv[local_n];
+	/* We don't use SRR here since we always want to round down. */
+	return val >> 32;
+}
+
+/*
+ * For updates fully spanning n periods, the contribution to runnable
+ * average will be: \Sum 1024*y^n
+ *
+ * We can compute this reasonably efficiently by combining:
+ *   y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for  n <PERIOD}
+ */
+static u32 __compute_runnable_contrib(u64 n)
+{
+	u32 contrib = 0;
+
+	if (likely(n <= LOAD_AVG_PERIOD))
+		return runnable_avg_yN_sum[n];
+	else if (unlikely(n >= LOAD_AVG_MAX_N))
+		return LOAD_AVG_MAX;
+
+	/* Compute \Sum k^n combining precomputed values for k^i, \Sum k^j */
+	do {
+		contrib /= 2; /* y^LOAD_AVG_PERIOD = 1/2 */
+		contrib += runnable_avg_yN_sum[LOAD_AVG_PERIOD];
+
+		n -= LOAD_AVG_PERIOD;
+	} while (n > LOAD_AVG_PERIOD);
+
+	contrib = decay_load(contrib, n);
+	return contrib + runnable_avg_yN_sum[n];
+}
+
+/*
+ * We can represent the historical contribution to runnable average as the
+ * coefficients of a geometric series.  To do this we sub-divide our runnable
+ * history into segments of approximately 1ms (1024us); label the segment that
+ * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g.
+ *
+ * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ...
+ *      p0            p1           p2
+ *     (now)       (~1ms ago)  (~2ms ago)
+ *
+ * Let u_i denote the fraction of p_i that the entity was runnable.
+ *
+ * We then designate the fractions u_i as our co-efficients, yielding the
+ * following representation of historical load:
+ *   u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ...
+ *
+ * We choose y based on the with of a reasonably scheduling period, fixing:
+ *   y^32 = 0.5
+ *
+ * This means that the contribution to load ~32ms ago (u_32) will be weighted
+ * approximately half as much as the contribution to load within the last ms
+ * (u_0).
+ *
+ * When a period "rolls over" and we have new u_0`, multiplying the previous
+ * sum again by y is sufficient to update:
+ *   load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... )
+ *            = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
+ */
+static __always_inline int __update_entity_runnable_avg(u64 now, int cpu,
+							struct sched_avg *sa,
+							int runnable,
+							int running)
+{
+	u64 delta, periods;
+	u32 runnable_contrib;
+	int delta_w, decayed = 0;
+	unsigned long scale_freq = arch_scale_freq_capacity(NULL, cpu);
+
+	delta = now - sa->last_runnable_update;
+	/*
+	 * This should only happen when time goes backwards, which it
+	 * unfortunately does during sched clock init when we swap over to TSC.
+	 */
+	if ((s64)delta < 0) {
+		sa->last_runnable_update = now;
+		return 0;
+	}
+
+	/*
+	 * Use 1024ns as the unit of measurement since it's a reasonable
+	 * approximation of 1us and fast to compute.
+	 */
+	delta >>= 10;
+	if (!delta)
+		return 0;
+	sa->last_runnable_update = now;
+
+	/* delta_w is the amount already accumulated against our next period */
+	delta_w = sa->avg_period % 1024;
+	if (delta + delta_w >= 1024) {
+		/* period roll-over */
+		decayed = 1;
+
+		/*
+		 * Now that we know we're crossing a period boundary, figure
+		 * out how much from delta we need to complete the current
+		 * period and accrue it.
+		 */
+		delta_w = 1024 - delta_w;
+		if (runnable)
+			sa->runnable_avg_sum += delta_w;
+		if (running)
+			sa->running_avg_sum += delta_w * scale_freq
+				>> SCHED_CAPACITY_SHIFT;
+		sa->avg_period += delta_w;
+
+		delta -= delta_w;
+
+		/* Figure out how many additional periods this update spans */
+		periods = delta / 1024;
+		delta %= 1024;
+
+		sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum,
+						  periods + 1);
+		sa->running_avg_sum = decay_load(sa->running_avg_sum,
+						  periods + 1);
+		sa->avg_period = decay_load(sa->avg_period,
+						     periods + 1);
+
+		/* Efficiently calculate \sum (1..n_period) 1024*y^i */
+		runnable_contrib = __compute_runnable_contrib(periods);
+		if (runnable)
+			sa->runnable_avg_sum += runnable_contrib;
+		if (running)
+			sa->running_avg_sum += runnable_contrib * scale_freq
+				>> SCHED_CAPACITY_SHIFT;
+		sa->avg_period += runnable_contrib;
+	}
+
+	/* Remainder of delta accrued against u_0` */
+	if (runnable)
+		sa->runnable_avg_sum += delta;
+	if (running)
+		sa->running_avg_sum += delta * scale_freq
+			>> SCHED_CAPACITY_SHIFT;
+	sa->avg_period += delta;
+
+	return decayed;
+}
+
+/* Synchronize an entity's decay with its parenting cfs_rq.*/
+static inline u64 __synchronize_entity_decay(struct sched_entity *se)
+{
+	struct cfs_rq *cfs_rq = cfs_rq_of(se);
+	u64 decays = atomic64_read(&cfs_rq->decay_counter);
+
+	decays -= se->avg.decay_count;
+	se->avg.decay_count = 0;
+	if (!decays)
+		return 0;
+
+	se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays);
+	se->avg.utilization_avg_contrib =
+		decay_load(se->avg.utilization_avg_contrib, decays);
+
+	return decays;
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
+						 int force_update)
+{
+	struct task_group *tg = cfs_rq->tg;
+	long tg_contrib;
+
+	tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg;
+	tg_contrib -= cfs_rq->tg_load_contrib;
+
+	if (!tg_contrib)
+		return;
+
+	if (force_update || abs(tg_contrib) > cfs_rq->tg_load_contrib / 8) {
+		atomic_long_add(tg_contrib, &tg->load_avg);
+		cfs_rq->tg_load_contrib += tg_contrib;
+	}
+}
+
+/*
+ * Aggregate cfs_rq runnable averages into an equivalent task_group
+ * representation for computing load contributions.
+ */
+static inline void __update_tg_runnable_avg(struct sched_avg *sa,
+						  struct cfs_rq *cfs_rq)
+{
+	struct task_group *tg = cfs_rq->tg;
+	long contrib;
+
+	/* The fraction of a cpu used by this cfs_rq */
+	contrib = div_u64((u64)sa->runnable_avg_sum << NICE_0_SHIFT,
+			  sa->avg_period + 1);
+	contrib -= cfs_rq->tg_runnable_contrib;
+
+	if (abs(contrib) > cfs_rq->tg_runnable_contrib / 64) {
+		atomic_add(contrib, &tg->runnable_avg);
+		cfs_rq->tg_runnable_contrib += contrib;
+	}
+}
+
+static inline void __update_group_entity_contrib(struct sched_entity *se)
+{
+	struct cfs_rq *cfs_rq = group_cfs_rq(se);
+	struct task_group *tg = cfs_rq->tg;
+	int runnable_avg;
+
+	u64 contrib;
+
+	contrib = cfs_rq->tg_load_contrib * tg->shares;
+	se->avg.load_avg_contrib = div_u64(contrib,
+				     atomic_long_read(&tg->load_avg) + 1);
+
+	/*
+	 * For group entities we need to compute a correction term in the case
+	 * that they are consuming <1 cpu so that we would contribute the same
+	 * load as a task of equal weight.
+	 *
+	 * Explicitly co-ordinating this measurement would be expensive, but
+	 * fortunately the sum of each cpus contribution forms a usable
+	 * lower-bound on the true value.
+	 *
+	 * Consider the aggregate of 2 contributions.  Either they are disjoint
+	 * (and the sum represents true value) or they are disjoint and we are
+	 * understating by the aggregate of their overlap.
+	 *
+	 * Extending this to N cpus, for a given overlap, the maximum amount we
+	 * understand is then n_i(n_i+1)/2 * w_i where n_i is the number of
+	 * cpus that overlap for this interval and w_i is the interval width.
+	 *
+	 * On a small machine; the first term is well-bounded which bounds the
+	 * total error since w_i is a subset of the period.  Whereas on a
+	 * larger machine, while this first term can be larger, if w_i is the
+	 * of consequential size guaranteed to see n_i*w_i quickly converge to
+	 * our upper bound of 1-cpu.
+	 */
+	runnable_avg = atomic_read(&tg->runnable_avg);
+	if (runnable_avg < NICE_0_LOAD) {
+		se->avg.load_avg_contrib *= runnable_avg;
+		se->avg.load_avg_contrib >>= NICE_0_SHIFT;
+	}
+}
+
+static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
+{
+	__update_entity_runnable_avg(rq_clock_task(rq), cpu_of(rq), &rq->avg,
+			runnable, runnable);
+	__update_tg_runnable_avg(&rq->avg, &rq->cfs);
+}
+#else /* CONFIG_FAIR_GROUP_SCHED */
+static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
+						 int force_update) {}
+static inline void __update_tg_runnable_avg(struct sched_avg *sa,
+						  struct cfs_rq *cfs_rq) {}
+static inline void __update_group_entity_contrib(struct sched_entity *se) {}
+static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
+static inline void __update_task_entity_contrib(struct sched_entity *se)
+{
+	u32 contrib;
+
+	/* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
+	contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);
+	contrib /= (se->avg.avg_period + 1);
+	se->avg.load_avg_contrib = scale_load(contrib);
+}
+
+/* Compute the current contribution to load_avg by se, return any delta */
+static long __update_entity_load_avg_contrib(struct sched_entity *se)
+{
+	long old_contrib = se->avg.load_avg_contrib;
+
+	if (entity_is_task(se)) {
+		__update_task_entity_contrib(se);
+	} else {
+		__update_tg_runnable_avg(&se->avg, group_cfs_rq(se));
+		__update_group_entity_contrib(se);
+	}
+
+	return se->avg.load_avg_contrib - old_contrib;
+}
+
+
+static inline void __update_task_entity_utilization(struct sched_entity *se)
+{
+	u32 contrib;
+
+	/* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
+	contrib = se->avg.running_avg_sum * scale_load_down(SCHED_LOAD_SCALE);
+	contrib /= (se->avg.avg_period + 1);
+	se->avg.utilization_avg_contrib = scale_load(contrib);
+}
+
+static long __update_entity_utilization_avg_contrib(struct sched_entity *se)
+{
+	long old_contrib = se->avg.utilization_avg_contrib;
+
+	if (entity_is_task(se))
+		__update_task_entity_utilization(se);
+	else
+		se->avg.utilization_avg_contrib =
+					group_cfs_rq(se)->utilization_load_avg;
+
+	return se->avg.utilization_avg_contrib - old_contrib;
+}
+
+static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq,
+						 long load_contrib)
+{
+	if (likely(load_contrib < cfs_rq->blocked_load_avg))
+		cfs_rq->blocked_load_avg -= load_contrib;
+	else
+		cfs_rq->blocked_load_avg = 0;
+}
+
+static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq);
+
+/* Update a sched_entity's runnable average */
+static inline void update_entity_load_avg(struct sched_entity *se,
+					  int update_cfs_rq)
+{
+	struct cfs_rq *cfs_rq = cfs_rq_of(se);
+	long contrib_delta, utilization_delta;
+	int cpu = cpu_of(rq_of(cfs_rq));
+	u64 now;
+
+	/*
+	 * For a group entity we need to use their owned cfs_rq_clock_task() in
+	 * case they are the parent of a throttled hierarchy.
+	 */
+	if (entity_is_task(se))
+		now = cfs_rq_clock_task(cfs_rq);
+	else
+		now = cfs_rq_clock_task(group_cfs_rq(se));
+
+	if (!__update_entity_runnable_avg(now, cpu, &se->avg, se->on_rq,
+					cfs_rq->curr == se))
+		return;
+
+	contrib_delta = __update_entity_load_avg_contrib(se);
+	utilization_delta = __update_entity_utilization_avg_contrib(se);
+
+	if (!update_cfs_rq)
+		return;
+
+	if (se->on_rq) {
+		cfs_rq->runnable_load_avg += contrib_delta;
+		cfs_rq->utilization_load_avg += utilization_delta;
+	} else {
+		subtract_blocked_load_contrib(cfs_rq, -contrib_delta);
+	}
+}
+
+/*
+ * Decay the load contributed by all blocked children and account this so that
+ * their contribution may appropriately discounted when they wake up.
+ */
+static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update)
+{
+	u64 now = cfs_rq_clock_task(cfs_rq) >> 20;
+	u64 decays;
+
+	decays = now - cfs_rq->last_decay;
+	if (!decays && !force_update)
+		return;
+
+	if (atomic_long_read(&cfs_rq->removed_load)) {
+		unsigned long removed_load;
+		removed_load = atomic_long_xchg(&cfs_rq->removed_load, 0);
+		subtract_blocked_load_contrib(cfs_rq, removed_load);
+	}
+
+	if (decays) {
+		cfs_rq->blocked_load_avg = decay_load(cfs_rq->blocked_load_avg,
+						      decays);
+		atomic64_add(decays, &cfs_rq->decay_counter);
+		cfs_rq->last_decay = now;
+	}
+
+	__update_cfs_rq_tg_load_contrib(cfs_rq, force_update);
+}
+
+/* Add the load generated by se into cfs_rq's child load-average */
+static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
+						  struct sched_entity *se,
+						  int wakeup)
+{
+	/*
+	 * We track migrations using entity decay_count <= 0, on a wake-up
+	 * migration we use a negative decay count to track the remote decays
+	 * accumulated while sleeping.
+	 *
+	 * Newly forked tasks are enqueued with se->avg.decay_count == 0, they
+	 * are seen by enqueue_entity_load_avg() as a migration with an already
+	 * constructed load_avg_contrib.
+	 */
+	if (unlikely(se->avg.decay_count <= 0)) {
+		se->avg.last_runnable_update = rq_clock_task(rq_of(cfs_rq));
+		if (se->avg.decay_count) {
+			/*
+			 * In a wake-up migration we have to approximate the
+			 * time sleeping.  This is because we can't synchronize
+			 * clock_task between the two cpus, and it is not
+			 * guaranteed to be read-safe.  Instead, we can
+			 * approximate this using our carried decays, which are
+			 * explicitly atomically readable.
+			 */
+			se->avg.last_runnable_update -= (-se->avg.decay_count)
+							<< 20;
+			update_entity_load_avg(se, 0);
+			/* Indicate that we're now synchronized and on-rq */
+			se->avg.decay_count = 0;
+		}
+		wakeup = 0;
+	} else {
+		__synchronize_entity_decay(se);
+	}
+
+	/* migrated tasks did not contribute to our blocked load */
+	if (wakeup) {
+		subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib);
+		update_entity_load_avg(se, 0);
+	}
+
+	cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
+	cfs_rq->utilization_load_avg += se->avg.utilization_avg_contrib;
+	/* we force update consideration on load-balancer moves */
+	update_cfs_rq_blocked_load(cfs_rq, !wakeup);
+}
+
+/*
+ * Remove se's load from this cfs_rq child load-average, if the entity is
+ * transitioning to a blocked state we track its projected decay using
+ * blocked_load_avg.
+ */
+static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
+						  struct sched_entity *se,
+						  int sleep)
+{
+	update_entity_load_avg(se, 1);
+	/* we force update consideration on load-balancer moves */
+	update_cfs_rq_blocked_load(cfs_rq, !sleep);
+
+	cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib;
+	cfs_rq->utilization_load_avg -= se->avg.utilization_avg_contrib;
+	if (sleep) {
+		cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
+		se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
+	} /* migrations, e.g. sleep=0 leave decay_count == 0 */
+}
+
+/*
+ * Update the rq's load with the elapsed running time before entering
+ * idle. if the last scheduled task is not a CFS task, idle_enter will
+ * be the only way to update the runnable statistic.
+ */
+void idle_enter_fair(struct rq *this_rq)
+{
+	update_rq_runnable_avg(this_rq, 1);
+}
+
+/*
+ * Update the rq's load with the elapsed idle time before a task is
+ * scheduled. if the newly scheduled task is not a CFS task, idle_exit will
+ * be the only way to update the runnable statistic.
+ */
+void idle_exit_fair(struct rq *this_rq)
+{
+	update_rq_runnable_avg(this_rq, 0);
+}
+
+static int idle_balance(struct rq *this_rq);
+
+#else /* CONFIG_SMP */
+
+static inline void update_entity_load_avg(struct sched_entity *se,
+					  int update_cfs_rq) {}
+static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
+static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
+					   struct sched_entity *se,
+					   int wakeup) {}
+static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
+					   struct sched_entity *se,
+					   int sleep) {}
+static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
+					      int force_update) {}
+
+static inline int idle_balance(struct rq *rq)
+{
+	return 0;
+}
+
+#endif /* CONFIG_SMP */
+
+static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+#ifdef CONFIG_SCHEDSTATS
+	struct task_struct *tsk = NULL;
+
+	if (entity_is_task(se))
+		tsk = task_of(se);
+
+	if (se->statistics.sleep_start) {
+		u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.sleep_start;
+
+		if ((s64)delta < 0)
+			delta = 0;
+
+		if (unlikely(delta > se->statistics.sleep_max))
+			se->statistics.sleep_max = delta;
+
+		se->statistics.sleep_start = 0;
+		se->statistics.sum_sleep_runtime += delta;
+
+		if (tsk) {
+			account_scheduler_latency(tsk, delta >> 10, 1);
+			trace_sched_stat_sleep(tsk, delta);
+		}
+	}
+	if (se->statistics.block_start) {
+		u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.block_start;
+
+		if ((s64)delta < 0)
+			delta = 0;
+
+		if (unlikely(delta > se->statistics.block_max))
+			se->statistics.block_max = delta;
+
+		se->statistics.block_start = 0;
+		se->statistics.sum_sleep_runtime += delta;
+
+		if (tsk) {
+			if (tsk->in_iowait) {
+				se->statistics.iowait_sum += delta;
+				se->statistics.iowait_count++;
+				trace_sched_stat_iowait(tsk, delta);
+			}
+
+			trace_sched_stat_blocked(tsk, delta);
+
+			/*
+			 * Blocking time is in units of nanosecs, so shift by
+			 * 20 to get a milliseconds-range estimation of the
+			 * amount of time that the task spent sleeping:
+			 */
+			if (unlikely(prof_on == SLEEP_PROFILING)) {
+				profile_hits(SLEEP_PROFILING,
+						(void *)get_wchan(tsk),
+						delta >> 20);
+			}
+			account_scheduler_latency(tsk, delta >> 10, 0);
+		}
+	}
+#endif
+}
+
+static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+#ifdef CONFIG_SCHED_DEBUG
+	s64 d = se->vruntime - cfs_rq->min_vruntime;
+
+	if (d < 0)
+		d = -d;
+
+	if (d > 3*sysctl_sched_latency)
+		schedstat_inc(cfs_rq, nr_spread_over);
+#endif
+}
+
+static void
+place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
+{
+	u64 vruntime = cfs_rq->min_vruntime;
+
+	/*
+	 * The 'current' period is already promised to the current tasks,
+	 * however the extra weight of the new task will slow them down a
+	 * little, place the new task so that it fits in the slot that
+	 * stays open at the end.
+	 */
+	if (initial && sched_feat(START_DEBIT))
+		vruntime += sched_vslice(cfs_rq, se);
+
+	/* sleeps up to a single latency don't count. */
+	if (!initial) {
+		unsigned long thresh = sysctl_sched_latency;
+
+		/*
+		 * Halve their sleep time's effect, to allow
+		 * for a gentler effect of sleepers:
+		 */
+		if (sched_feat(GENTLE_FAIR_SLEEPERS))
+			thresh >>= 1;
+
+		vruntime -= thresh;
+	}
+
+	/* ensure we never gain time by being placed backwards. */
+	se->vruntime = max_vruntime(se->vruntime, vruntime);
+}
+
+static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
+
+static void
+enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
+{
+	/*
+	 * Update the normalized vruntime before updating min_vruntime
+	 * through calling update_curr().
+	 */
+	if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING))
+		se->vruntime += cfs_rq->min_vruntime;
+
+	/*
+	 * Update run-time statistics of the 'current'.
+	 */
+	update_curr(cfs_rq);
+	enqueue_entity_load_avg(cfs_rq, se, flags & ENQUEUE_WAKEUP);
+	account_entity_enqueue(cfs_rq, se);
+	update_cfs_shares(cfs_rq);
+
+	if (flags & ENQUEUE_WAKEUP) {
+		place_entity(cfs_rq, se, 0);
+		enqueue_sleeper(cfs_rq, se);
+	}
+
+	update_stats_enqueue(cfs_rq, se);
+	check_spread(cfs_rq, se);
+	if (se != cfs_rq->curr)
+		__enqueue_entity(cfs_rq, se);
+	se->on_rq = 1;
+
+	if (cfs_rq->nr_running == 1) {
+		list_add_leaf_cfs_rq(cfs_rq);
+		check_enqueue_throttle(cfs_rq);
+	}
+}
+
+static void __clear_buddies_last(struct sched_entity *se)
+{
+	for_each_sched_entity(se) {
+		struct cfs_rq *cfs_rq = cfs_rq_of(se);
+		if (cfs_rq->last != se)
+			break;
+
+		cfs_rq->last = NULL;
+	}
+}
+
+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)
+			break;
+
+		cfs_rq->next = NULL;
+	}
+}
+
+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)
+			break;
+
+		cfs_rq->skip = NULL;
+	}
+}
+
+static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	if (cfs_rq->last == se)
+		__clear_buddies_last(se);
+
+	if (cfs_rq->next == se)
+		__clear_buddies_next(se);
+
+	if (cfs_rq->skip == se)
+		__clear_buddies_skip(se);
+}
+
+static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
+
+static void
+dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
+{
+	/*
+	 * Update run-time statistics of the 'current'.
+	 */
+	update_curr(cfs_rq);
+	dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP);
+
+	update_stats_dequeue(cfs_rq, se);
+	if (flags & DEQUEUE_SLEEP) {
+#ifdef CONFIG_SCHEDSTATS
+		if (entity_is_task(se)) {
+			struct task_struct *tsk = task_of(se);
+
+			if (tsk->state & TASK_INTERRUPTIBLE)
+				se->statistics.sleep_start = rq_clock(rq_of(cfs_rq));
+			if (tsk->state & TASK_UNINTERRUPTIBLE)
+				se->statistics.block_start = rq_clock(rq_of(cfs_rq));
+		}
+#endif
+	}
+
+	clear_buddies(cfs_rq, se);
+
+	if (se != cfs_rq->curr)
+		__dequeue_entity(cfs_rq, se);
+	se->on_rq = 0;
+	account_entity_dequeue(cfs_rq, se);
+
+	/*
+	 * Normalize the entity after updating the min_vruntime because the
+	 * update can refer to the ->curr item and we need to reflect this
+	 * movement in our normalized position.
+	 */
+	if (!(flags & DEQUEUE_SLEEP))
+		se->vruntime -= cfs_rq->min_vruntime;
+
+	/* return excess runtime on last dequeue */
+	return_cfs_rq_runtime(cfs_rq);
+
+	update_min_vruntime(cfs_rq);
+	update_cfs_shares(cfs_rq);
+}
+
+/*
+ * Preempt the current task with a newly woken task if needed:
+ */
+static void
+check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
+{
+	unsigned long ideal_runtime, delta_exec;
+	struct sched_entity *se;
+	s64 delta;
+
+	ideal_runtime = sched_slice(cfs_rq, curr);
+	delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
+	if (delta_exec > ideal_runtime) {
+		resched_curr(rq_of(cfs_rq));
+		/*
+		 * The current task ran long enough, ensure it doesn't get
+		 * re-elected due to buddy favours.
+		 */
+		clear_buddies(cfs_rq, curr);
+		return;
+	}
+
+	/*
+	 * Ensure that a task that missed wakeup preemption by a
+	 * narrow margin doesn't have to wait for a full slice.
+	 * This also mitigates buddy induced latencies under load.
+	 */
+	if (delta_exec < sysctl_sched_min_granularity)
+		return;
+
+	se = __pick_first_entity(cfs_rq);
+	delta = curr->vruntime - se->vruntime;
+
+	if (delta < 0)
+		return;
+
+	if (delta > ideal_runtime)
+		resched_curr(rq_of(cfs_rq));
+}
+
+static void
+set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	/* 'current' is not kept within the tree. */
+	if (se->on_rq) {
+		/*
+		 * Any task has to be enqueued before it get to execute on
+		 * a CPU. So account for the time it spent waiting on the
+		 * runqueue.
+		 */
+		update_stats_wait_end(cfs_rq, se);
+		__dequeue_entity(cfs_rq, se);
+		update_entity_load_avg(se, 1);
+	}
+
+	update_stats_curr_start(cfs_rq, se);
+	cfs_rq->curr = se;
+#ifdef CONFIG_SCHEDSTATS
+	/*
+	 * Track our maximum slice length, if the CPU's load is at
+	 * least twice that of our own weight (i.e. dont track it
+	 * when there are only lesser-weight tasks around):
+	 */
+	if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
+		se->statistics.slice_max = max(se->statistics.slice_max,
+			se->sum_exec_runtime - se->prev_sum_exec_runtime);
+	}
+#endif
+	se->prev_sum_exec_runtime = se->sum_exec_runtime;
+}
+
+static int
+wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
+
+/*
+ * Pick the next process, keeping these things in mind, in this order:
+ * 1) keep things fair between processes/task groups
+ * 2) pick the "next" process, since someone really wants that to run
+ * 3) pick the "last" process, for cache locality
+ * 4) do not run the "skip" process, if something else is available
+ */
+static struct sched_entity *
+pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr)
+{
+	struct sched_entity *left = __pick_first_entity(cfs_rq);
+	struct sched_entity *se;
+
+	/*
+	 * If curr is set we have to see if its left of the leftmost entity
+	 * still in the tree, provided there was anything in the tree at all.
+	 */
+	if (!left || (curr && entity_before(curr, left)))
+		left = curr;
+
+	se = left; /* ideally we run the leftmost entity */
+
+	/*
+	 * 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;
+
+		if (se == curr) {
+			second = __pick_first_entity(cfs_rq);
+		} else {
+			second = __pick_next_entity(se);
+			if (!second || (curr && entity_before(curr, second)))
+				second = curr;
+		}
+
+		if (second && wakeup_preempt_entity(second, left) < 1)
+			se = second;
+	}
+
+	/*
+	 * Prefer last buddy, try to return the CPU to a preempted task.
+	 */
+	if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
+		se = cfs_rq->last;
+
+	/*
+	 * Someone really wants this to run. If it's not unfair, run it.
+	 */
+	if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
+		se = cfs_rq->next;
+
+	clear_buddies(cfs_rq, se);
+
+	return se;
+}
+
+static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
+
+static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
+{
+	/*
+	 * If still on the runqueue then deactivate_task()
+	 * was not called and update_curr() has to be done:
+	 */
+	if (prev->on_rq)
+		update_curr(cfs_rq);
+
+	/* throttle cfs_rqs exceeding runtime */
+	check_cfs_rq_runtime(cfs_rq);
+
+	check_spread(cfs_rq, prev);
+	if (prev->on_rq) {
+		update_stats_wait_start(cfs_rq, prev);
+		/* Put 'current' back into the tree. */
+		__enqueue_entity(cfs_rq, prev);
+		/* in !on_rq case, update occurred at dequeue */
+		update_entity_load_avg(prev, 1);
+	}
+	cfs_rq->curr = NULL;
+}
+
+static void
+entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
+{
+	/*
+	 * Update run-time statistics of the 'current'.
+	 */
+	update_curr(cfs_rq);
+
+	/*
+	 * Ensure that runnable average is periodically updated.
+	 */
+	update_entity_load_avg(curr, 1);
+	update_cfs_rq_blocked_load(cfs_rq, 1);
+	update_cfs_shares(cfs_rq);
+
+#ifdef CONFIG_SCHED_HRTICK
+	/*
+	 * queued ticks are scheduled to match the slice, so don't bother
+	 * validating it and just reschedule.
+	 */
+	if (queued) {
+		resched_curr(rq_of(cfs_rq));
+		return;
+	}
+	/*
+	 * don't let the period tick interfere with the hrtick preemption
+	 */
+	if (!sched_feat(DOUBLE_TICK) &&
+			hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
+		return;
+#endif
+
+	if (cfs_rq->nr_running > 1)
+		check_preempt_tick(cfs_rq, curr);
+}
+
+
+/**************************************************
+ * CFS bandwidth control machinery
+ */
+
+#ifdef CONFIG_CFS_BANDWIDTH
+
+#ifdef HAVE_JUMP_LABEL
+static struct static_key __cfs_bandwidth_used;
+
+static inline bool cfs_bandwidth_used(void)
+{
+	return static_key_false(&__cfs_bandwidth_used);
+}
+
+void cfs_bandwidth_usage_inc(void)
+{
+	static_key_slow_inc(&__cfs_bandwidth_used);
+}
+
+void cfs_bandwidth_usage_dec(void)
+{
+	static_key_slow_dec(&__cfs_bandwidth_used);
+}
+#else /* HAVE_JUMP_LABEL */
+static bool cfs_bandwidth_used(void)
+{
+	return true;
+}
+
+void cfs_bandwidth_usage_inc(void) {}
+void cfs_bandwidth_usage_dec(void) {}
+#endif /* HAVE_JUMP_LABEL */
+
+/*
+ * default period for cfs group bandwidth.
+ * default: 0.1s, units: nanoseconds
+ */
+static inline u64 default_cfs_period(void)
+{
+	return 100000000ULL;
+}
+
+static inline u64 sched_cfs_bandwidth_slice(void)
+{
+	return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
+}
+
+/*
+ * Replenish runtime according to assigned quota and update expiration time.
+ * We use sched_clock_cpu directly instead of rq->clock to avoid adding
+ * additional synchronization around rq->lock.
+ *
+ * requires cfs_b->lock
+ */
+void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
+{
+	u64 now;
+
+	if (cfs_b->quota == RUNTIME_INF)
+		return;
+
+	now = sched_clock_cpu(smp_processor_id());
+	cfs_b->runtime = cfs_b->quota;
+	cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period);
+}
+
+static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
+{
+	return &tg->cfs_bandwidth;
+}
+
+/* rq->task_clock normalized against any time this cfs_rq has spent throttled */
+static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
+{
+	if (unlikely(cfs_rq->throttle_count))
+		return cfs_rq->throttled_clock_task;
+
+	return rq_clock_task(rq_of(cfs_rq)) - cfs_rq->throttled_clock_task_time;
+}
+
+/* returns 0 on failure to allocate runtime */
+static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+	struct task_group *tg = cfs_rq->tg;
+	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
+	u64 amount = 0, min_amount, expires;
+
+	/* note: this is a positive sum as runtime_remaining <= 0 */
+	min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining;
+
+	raw_spin_lock(&cfs_b->lock);
+	if (cfs_b->quota == RUNTIME_INF)
+		amount = min_amount;
+	else {
+		/*
+		 * If the bandwidth pool has become inactive, then at least one
+		 * period must have elapsed since the last consumption.
+		 * Refresh the global state and ensure bandwidth timer becomes
+		 * active.
+		 */
+		if (!cfs_b->timer_active) {
+			__refill_cfs_bandwidth_runtime(cfs_b);
+			__start_cfs_bandwidth(cfs_b, false);
+		}
+
+		if (cfs_b->runtime > 0) {
+			amount = min(cfs_b->runtime, min_amount);
+			cfs_b->runtime -= amount;
+			cfs_b->idle = 0;
+		}
+	}
+	expires = cfs_b->runtime_expires;
+	raw_spin_unlock(&cfs_b->lock);
+
+	cfs_rq->runtime_remaining += amount;
+	/*
+	 * we may have advanced our local expiration to account for allowed
+	 * spread between our sched_clock and the one on which runtime was
+	 * issued.
+	 */
+	if ((s64)(expires - cfs_rq->runtime_expires) > 0)
+		cfs_rq->runtime_expires = expires;
+
+	return cfs_rq->runtime_remaining > 0;
+}
+
+/*
+ * Note: This depends on the synchronization provided by sched_clock and the
+ * fact that rq->clock snapshots this value.
+ */
+static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+
+	/* if the deadline is ahead of our clock, nothing to do */
+	if (likely((s64)(rq_clock(rq_of(cfs_rq)) - cfs_rq->runtime_expires) < 0))
+		return;
+
+	if (cfs_rq->runtime_remaining < 0)
+		return;
+
+	/*
+	 * If the local deadline has passed we have to consider the
+	 * possibility that our sched_clock is 'fast' and the global deadline
+	 * has not truly expired.
+	 *
+	 * Fortunately we can check determine whether this the case by checking
+	 * whether the global deadline has advanced. It is valid to compare
+	 * cfs_b->runtime_expires without any locks since we only care about
+	 * exact equality, so a partial write will still work.
+	 */
+
+	if (cfs_rq->runtime_expires != cfs_b->runtime_expires) {
+		/* 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, u64 delta_exec)
+{
+	/* dock delta_exec before expiring quota (as it could span periods) */
+	cfs_rq->runtime_remaining -= delta_exec;
+	expire_cfs_rq_runtime(cfs_rq);
+
+	if (likely(cfs_rq->runtime_remaining > 0))
+		return;
+
+	/*
+	 * if we're unable to extend our runtime we resched so that the active
+	 * hierarchy can be throttled
+	 */
+	if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
+		resched_curr(rq_of(cfs_rq));
+}
+
+static __always_inline
+void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
+{
+	if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
+		return;
+
+	__account_cfs_rq_runtime(cfs_rq, delta_exec);
+}
+
+static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
+{
+	return cfs_bandwidth_used() && cfs_rq->throttled;
+}
+
+/* check whether cfs_rq, or any parent, is throttled */
+static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
+{
+	return cfs_bandwidth_used() && cfs_rq->throttle_count;
+}
+
+/*
+ * Ensure that neither of the group entities corresponding to src_cpu or
+ * dest_cpu are members of a throttled hierarchy when performing group
+ * load-balance operations.
+ */
+static inline int throttled_lb_pair(struct task_group *tg,
+				    int src_cpu, int dest_cpu)
+{
+	struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
+
+	src_cfs_rq = tg->cfs_rq[src_cpu];
+	dest_cfs_rq = tg->cfs_rq[dest_cpu];
+
+	return throttled_hierarchy(src_cfs_rq) ||
+	       throttled_hierarchy(dest_cfs_rq);
+}
+
+/* updated child weight may affect parent so we have to do this bottom up */
+static int tg_unthrottle_up(struct task_group *tg, void *data)
+{
+	struct rq *rq = data;
+	struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
+
+	cfs_rq->throttle_count--;
+#ifdef CONFIG_SMP
+	if (!cfs_rq->throttle_count) {
+		/* adjust cfs_rq_clock_task() */
+		cfs_rq->throttled_clock_task_time += rq_clock_task(rq) -
+					     cfs_rq->throttled_clock_task;
+	}
+#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, stop time */
+	if (!cfs_rq->throttle_count)
+		cfs_rq->throttled_clock_task = rq_clock_task(rq);
+	cfs_rq->throttle_count++;
+
+	return 0;
+}
+
+static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
+{
+	struct rq *rq = rq_of(cfs_rq);
+	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+	struct sched_entity *se;
+	long task_delta, dequeue = 1;
+
+	se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
+
+	/* freeze hierarchy runnable averages while throttled */
+	rcu_read_lock();
+	walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
+	rcu_read_unlock();
+
+	task_delta = cfs_rq->h_nr_running;
+	for_each_sched_entity(se) {
+		struct cfs_rq *qcfs_rq = cfs_rq_of(se);
+		/* throttled entity or throttle-on-deactivate */
+		if (!se->on_rq)
+			break;
+
+		if (dequeue)
+			dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
+		qcfs_rq->h_nr_running -= task_delta;
+
+		if (qcfs_rq->load.weight)
+			dequeue = 0;
+	}
+
+	if (!se)
+		sub_nr_running(rq, task_delta);
+
+	cfs_rq->throttled = 1;
+	cfs_rq->throttled_clock = rq_clock(rq);
+	raw_spin_lock(&cfs_b->lock);
+	/*
+	 * Add to the _head_ of the list, so that an already-started
+	 * distribute_cfs_runtime will not see us
+	 */
+	list_add_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
+	if (!cfs_b->timer_active)
+		__start_cfs_bandwidth(cfs_b, false);
+	raw_spin_unlock(&cfs_b->lock);
+}
+
+void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
+{
+	struct rq *rq = rq_of(cfs_rq);
+	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+	struct sched_entity *se;
+	int enqueue = 1;
+	long task_delta;
+
+	se = cfs_rq->tg->se[cpu_of(rq)];
+
+	cfs_rq->throttled = 0;
+
+	update_rq_clock(rq);
+
+	raw_spin_lock(&cfs_b->lock);
+	cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock;
+	list_del_rcu(&cfs_rq->throttled_list);
+	raw_spin_unlock(&cfs_b->lock);
+
+	/* update hierarchical throttle state */
+	walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
+
+	if (!cfs_rq->load.weight)
+		return;
+
+	task_delta = cfs_rq->h_nr_running;
+	for_each_sched_entity(se) {
+		if (se->on_rq)
+			enqueue = 0;
+
+		cfs_rq = cfs_rq_of(se);
+		if (enqueue)
+			enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);
+		cfs_rq->h_nr_running += task_delta;
+
+		if (cfs_rq_throttled(cfs_rq))
+			break;
+	}
+
+	if (!se)
+		add_nr_running(rq, task_delta);
+
+	/* determine whether we need to wake up potentially idle cpu */
+	if (rq->curr == rq->idle && rq->cfs.nr_running)
+		resched_curr(rq);
+}
+
+static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
+		u64 remaining, u64 expires)
+{
+	struct cfs_rq *cfs_rq;
+	u64 runtime;
+	u64 starting_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 starting_runtime - remaining;
+}
+
+/*
+ * Responsible for refilling a task_group's bandwidth and unthrottling its
+ * cfs_rqs as appropriate. If there has been no activity within the last
+ * period the timer is deactivated until scheduling resumes; cfs_b->idle is
+ * used to track this state.
+ */
+static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
+{
+	u64 runtime, runtime_expires;
+	int throttled;
+
+	/* no need to continue the timer with no bandwidth constraint */
+	if (cfs_b->quota == RUNTIME_INF)
+		goto out_deactivate;
+
+	throttled = !list_empty(&cfs_b->throttled_cfs_rq);
+	cfs_b->nr_periods += overrun;
+
+	/*
+	 * idle depends on !throttled (for the case of a large deficit), and if
+	 * we're going inactive then everything else can be deferred
+	 */
+	if (cfs_b->idle && !throttled)
+		goto out_deactivate;
+
+	/*
+	 * if we have relooped after returning idle once, we need to update our
+	 * status as actually running, so that other cpus doing
+	 * __start_cfs_bandwidth will stop trying to cancel us.
+	 */
+	cfs_b->timer_active = 1;
+
+	__refill_cfs_bandwidth_runtime(cfs_b);
+
+	if (!throttled) {
+		/* mark as potentially idle for the upcoming period */
+		cfs_b->idle = 1;
+		return 0;
+	}
+
+	/* account preceding periods in which throttling occurred */
+	cfs_b->nr_throttled += overrun;
+
+	runtime_expires = cfs_b->runtime_expires;
+
+	/*
+	 * 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. This can result
+	 * in us over-using our runtime if it is all used during this loop, but
+	 * only by limited amounts in that extreme case.
+	 */
+	while (throttled && cfs_b->runtime > 0) {
+		runtime = cfs_b->runtime;
+		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);
+
+		cfs_b->runtime -= min(runtime, cfs_b->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;
+
+	return 0;
+
+out_deactivate:
+	cfs_b->timer_active = 0;
+	return 1;
+}
+
+/* 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?
+ *
+ * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the
+ * hrtimer base being cleared by __hrtimer_start_range_ns. In the case of
+ * migrate_hrtimers, base is never cleared, so we are fine.
+ */
+static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
+{
+	struct hrtimer *refresh_timer = &cfs_b->period_timer;
+	u64 remaining;
+
+	/* if the call-back is running a quota refresh is already occurring */
+	if (hrtimer_callback_running(refresh_timer))
+		return 1;
+
+	/* is a quota refresh about to occur? */
+	remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
+	if (remaining < min_expire)
+		return 1;
+
+	return 0;
+}
+
+static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
+{
+	u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
+
+	/* if there's a quota refresh soon don't bother with slack */
+	if (runtime_refresh_within(cfs_b, min_left))
+		return;
+
+	start_bandwidth_timer(&cfs_b->slack_timer,
+				ns_to_ktime(cfs_bandwidth_slack_period));
+}
+
+/* we know any runtime found here is valid as update_curr() precedes return */
+static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+	s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
+
+	if (slack_runtime <= 0)
+		return;
+
+	raw_spin_lock(&cfs_b->lock);
+	if (cfs_b->quota != RUNTIME_INF &&
+	    cfs_rq->runtime_expires == cfs_b->runtime_expires) {
+		cfs_b->runtime += slack_runtime;
+
+		/* we are under rq->lock, defer unthrottling using a timer */
+		if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
+		    !list_empty(&cfs_b->throttled_cfs_rq))
+			start_cfs_slack_bandwidth(cfs_b);
+	}
+	raw_spin_unlock(&cfs_b->lock);
+
+	/* even if it's not valid for return we don't want to try again */
+	cfs_rq->runtime_remaining -= slack_runtime;
+}
+
+static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+	if (!cfs_bandwidth_used())
+		return;
+
+	if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
+		return;
+
+	__return_cfs_rq_runtime(cfs_rq);
+}
+
+/*
+ * This is done with a timer (instead of inline with bandwidth return) since
+ * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
+ */
+static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
+{
+	u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
+	u64 expires;
+
+	/* confirm we're still not at a refresh boundary */
+	raw_spin_lock(&cfs_b->lock);
+	if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) {
+		raw_spin_unlock(&cfs_b->lock);
+		return;
+	}
+
+	if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice)
+		runtime = cfs_b->runtime;
+
+	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 -= min(runtime, cfs_b->runtime);
+	raw_spin_unlock(&cfs_b->lock);
+}
+
+/*
+ * When a group wakes up we want to make sure that its quota is not already
+ * expired/exceeded, otherwise it may be allowed to steal additional ticks of
+ * runtime as update_curr() throttling can not not trigger until it's on-rq.
+ */
+static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
+{
+	if (!cfs_bandwidth_used())
+		return;
+
+	/* an active group must be handled by the update_curr()->put() path */
+	if (!cfs_rq->runtime_enabled || cfs_rq->curr)
+		return;
+
+	/* ensure the group is not already throttled */
+	if (cfs_rq_throttled(cfs_rq))
+		return;
+
+	/* update runtime allocation */
+	account_cfs_rq_runtime(cfs_rq, 0);
+	if (cfs_rq->runtime_remaining <= 0)
+		throttle_cfs_rq(cfs_rq);
+}
+
+/* conditionally throttle active cfs_rq's from put_prev_entity() */
+static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+	if (!cfs_bandwidth_used())
+		return false;
+
+	if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
+		return false;
+
+	/*
+	 * 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 true;
+
+	throttle_cfs_rq(cfs_rq);
+	return true;
+}
+
+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;
+
+	raw_spin_lock(&cfs_b->lock);
+	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);
+	}
+	raw_spin_unlock(&cfs_b->lock);
+
+	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, bool force)
+{
+	/*
+	 * 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)) &&
+	       hrtimer_try_to_cancel(&cfs_b->period_timer) < 0) {
+		/* bounce the lock to allow do_sched_cfs_period_timer to run */
+		raw_spin_unlock(&cfs_b->lock);
+		cpu_relax();
+		raw_spin_lock(&cfs_b->lock);
+		/* if someone else restarted the timer then we're done */
+		if (!force && 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)
+{
+	/* init_cfs_bandwidth() was not called */
+	if (!cfs_b->throttled_cfs_rq.next)
+		return;
+
+	hrtimer_cancel(&cfs_b->period_timer);
+	hrtimer_cancel(&cfs_b->slack_timer);
+}
+
+static void __maybe_unused update_runtime_enabled(struct rq *rq)
+{
+	struct cfs_rq *cfs_rq;
+
+	for_each_leaf_cfs_rq(rq, cfs_rq) {
+		struct cfs_bandwidth *cfs_b = &cfs_rq->tg->cfs_bandwidth;
+
+		raw_spin_lock(&cfs_b->lock);
+		cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
+		raw_spin_unlock(&cfs_b->lock);
+	}
+}
+
+static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
+{
+	struct cfs_rq *cfs_rq;
+
+	for_each_leaf_cfs_rq(rq, cfs_rq) {
+		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 = 1;
+		/*
+		 * Offline rq is schedulable till cpu is completely disabled
+		 * in take_cpu_down(), so we prevent new cfs throttling here.
+		 */
+		cfs_rq->runtime_enabled = 0;
+
+		if (cfs_rq_throttled(cfs_rq))
+			unthrottle_cfs_rq(cfs_rq);
+	}
+}
+
+#else /* CONFIG_CFS_BANDWIDTH */
+static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
+{
+	return rq_clock_task(rq_of(cfs_rq));
+}
+
+static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {}
+static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; }
+static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
+static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
+
+static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
+{
+	return 0;
+}
+
+static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
+{
+	return 0;
+}
+
+static inline int throttled_lb_pair(struct task_group *tg,
+				    int src_cpu, int dest_cpu)
+{
+	return 0;
+}
+
+void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
+#endif
+
+static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
+{
+	return NULL;
+}
+static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
+static inline void update_runtime_enabled(struct rq *rq) {}
+static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
+
+#endif /* CONFIG_CFS_BANDWIDTH */
+
+/**************************************************
+ * CFS operations on tasks:
+ */
+
+#ifdef CONFIG_SCHED_HRTICK
+static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
+{
+	struct sched_entity *se = &p->se;
+	struct cfs_rq *cfs_rq = cfs_rq_of(se);
+
+	WARN_ON(task_rq(p) != rq);
+
+	if (cfs_rq->nr_running > 1) {
+		u64 slice = sched_slice(cfs_rq, se);
+		u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
+		s64 delta = slice - ran;
+
+		if (delta < 0) {
+			if (rq->curr == p)
+				resched_curr(rq);
+			return;
+		}
+		hrtick_start(rq, delta);
+	}
+}
+
+/*
+ * called from enqueue/dequeue and updates the hrtick when the
+ * current task is from our class and nr_running is low enough
+ * to matter.
+ */
+static void hrtick_update(struct rq *rq)
+{
+	struct task_struct *curr = rq->curr;
+
+	if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class)
+		return;
+
+	if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
+		hrtick_start_fair(rq, curr);
+}
+#else /* !CONFIG_SCHED_HRTICK */
+static inline void
+hrtick_start_fair(struct rq *rq, struct task_struct *p)
+{
+}
+
+static inline void hrtick_update(struct rq *rq)
+{
+}
+#endif
+
+/*
+ * The enqueue_task method is called before nr_running is
+ * increased. Here we update the fair scheduling stats and
+ * then put the task into the rbtree:
+ */
+static void
+enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
+{
+	struct cfs_rq *cfs_rq;
+	struct sched_entity *se = &p->se;
+
+	for_each_sched_entity(se) {
+		if (se->on_rq)
+			break;
+		cfs_rq = cfs_rq_of(se);
+		enqueue_entity(cfs_rq, se, flags);
+
+		/*
+		 * end evaluation on encountering a throttled cfs_rq
+		 *
+		 * note: in the case of encountering a throttled cfs_rq we will
+		 * post the final h_nr_running increment below.
+		*/
+		if (cfs_rq_throttled(cfs_rq))
+			break;
+		cfs_rq->h_nr_running++;
+
+		flags = ENQUEUE_WAKEUP;
+	}
+
+	for_each_sched_entity(se) {
+		cfs_rq = cfs_rq_of(se);
+		cfs_rq->h_nr_running++;
+
+		if (cfs_rq_throttled(cfs_rq))
+			break;
+
+		update_cfs_shares(cfs_rq);
+		update_entity_load_avg(se, 1);
+	}
+
+	if (!se) {
+		update_rq_runnable_avg(rq, rq->nr_running);
+		add_nr_running(rq, 1);
+	}
+	hrtick_update(rq);
+}
+
+static void set_next_buddy(struct sched_entity *se);
+
+/*
+ * The dequeue_task method is called before nr_running is
+ * decreased. We remove the task from the rbtree and
+ * update the fair scheduling stats:
+ */
+static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
+{
+	struct cfs_rq *cfs_rq;
+	struct sched_entity *se = &p->se;
+	int task_sleep = flags & DEQUEUE_SLEEP;
+
+	for_each_sched_entity(se) {
+		cfs_rq = cfs_rq_of(se);
+		dequeue_entity(cfs_rq, se, flags);
+
+		/*
+		 * end evaluation on encountering a throttled cfs_rq
+		 *
+		 * note: in the case of encountering a throttled cfs_rq we will
+		 * post the final h_nr_running decrement below.
+		*/
+		if (cfs_rq_throttled(cfs_rq))
+			break;
+		cfs_rq->h_nr_running--;
+
+		/* Don't dequeue parent if it has other entities besides us */
+		if (cfs_rq->load.weight) {
+			/*
+			 * Bias pick_next to pick a task from this cfs_rq, as
+			 * p is sleeping when it is within its sched_slice.
+			 */
+			if (task_sleep && parent_entity(se))
+				set_next_buddy(parent_entity(se));
+
+			/* avoid re-evaluating load for this entity */
+			se = parent_entity(se);
+			break;
+		}
+		flags |= DEQUEUE_SLEEP;
+	}
+
+	for_each_sched_entity(se) {
+		cfs_rq = cfs_rq_of(se);
+		cfs_rq->h_nr_running--;
+
+		if (cfs_rq_throttled(cfs_rq))
+			break;
+
+		update_cfs_shares(cfs_rq);
+		update_entity_load_avg(se, 1);
+	}
+
+	if (!se) {
+		sub_nr_running(rq, 1);
+		update_rq_runnable_avg(rq, 1);
+	}
+	hrtick_update(rq);
+}
+
+#ifdef CONFIG_SMP
+/* Used instead of source_load when we know the type == 0 */
+static unsigned long weighted_cpuload(const int cpu)
+{
+	return cpu_rq(cpu)->cfs.runnable_load_avg;
+}
+
+/*
+ * 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 capacity_of(int cpu)
+{
+	return cpu_rq(cpu)->cpu_capacity;
+}
+
+static unsigned long capacity_orig_of(int cpu)
+{
+	return cpu_rq(cpu)->cpu_capacity_orig;
+}
+
+static unsigned long cpu_avg_load_per_task(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	unsigned long nr_running = ACCESS_ONCE(rq->cfs.h_nr_running);
+	unsigned long load_avg = rq->cfs.runnable_load_avg;
+
+	if (nr_running)
+		return load_avg / nr_running;
+
+	return 0;
+}
+
+static void record_wakee(struct task_struct *p)
+{
+	/*
+	 * Rough decay (wiping) for cost saving, don't worry
+	 * about the boundary, really active task won't care
+	 * about the loss.
+	 */
+	if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) {
+		current->wakee_flips >>= 1;
+		current->wakee_flip_decay_ts = jiffies;
+	}
+
+	if (current->last_wakee != p) {
+		current->last_wakee = p;
+		current->wakee_flips++;
+	}
+}
+
+static void task_waking_fair(struct task_struct *p)
+{
+	struct sched_entity *se = &p->se;
+	struct cfs_rq *cfs_rq = cfs_rq_of(se);
+	u64 min_vruntime;
+
+#ifndef CONFIG_64BIT
+	u64 min_vruntime_copy;
+
+	do {
+		min_vruntime_copy = cfs_rq->min_vruntime_copy;
+		smp_rmb();
+		min_vruntime = cfs_rq->min_vruntime;
+	} while (min_vruntime != min_vruntime_copy);
+#else
+	min_vruntime = cfs_rq->min_vruntime;
+#endif
+
+	se->vruntime -= min_vruntime;
+	record_wakee(p);
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+/*
+ * effective_load() calculates the load change as seen from the root_task_group
+ *
+ * Adding load to a group doesn't make a group heavier, but can cause movement
+ * of group shares between cpus. Assuming the shares were perfectly aligned one
+ * can calculate the shift in shares.
+ *
+ * Calculate the effective load difference if @wl is added (subtracted) to @tg
+ * on this @cpu and results in a total addition (subtraction) of @wg to the
+ * total group weight.
+ *
+ * Given a runqueue weight distribution (rw_i) we can compute a shares
+ * distribution (s_i) using:
+ *
+ *   s_i = rw_i / \Sum rw_j						(1)
+ *
+ * Suppose we have 4 CPUs and our @tg is a direct child of the root group and
+ * has 7 equal weight tasks, distributed as below (rw_i), with the resulting
+ * shares distribution (s_i):
+ *
+ *   rw_i = {   2,   4,   1,   0 }
+ *   s_i  = { 2/7, 4/7, 1/7,   0 }
+ *
+ * As per wake_affine() we're interested in the load of two CPUs (the CPU the
+ * task used to run on and the CPU the waker is running on), we need to
+ * compute the effect of waking a task on either CPU and, in case of a sync
+ * wakeup, compute the effect of the current task going to sleep.
+ *
+ * So for a change of @wl to the local @cpu with an overall group weight change
+ * of @wl we can compute the new shares distribution (s'_i) using:
+ *
+ *   s'_i = (rw_i + @wl) / (@wg + \Sum rw_j)				(2)
+ *
+ * Suppose we're interested in CPUs 0 and 1, and want to compute the load
+ * differences in waking a task to CPU 0. The additional task changes the
+ * weight and shares distributions like:
+ *
+ *   rw'_i = {   3,   4,   1,   0 }
+ *   s'_i  = { 3/8, 4/8, 1/8,   0 }
+ *
+ * We can then compute the difference in effective weight by using:
+ *
+ *   dw_i = S * (s'_i - s_i)						(3)
+ *
+ * Where 'S' is the group weight as seen by its parent.
+ *
+ * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7)
+ * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 -
+ * 4/7) times the weight of the group.
+ */
+static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
+{
+	struct sched_entity *se = tg->se[cpu];
+
+	if (!tg->parent)	/* the trivial, non-cgroup case */
+		return wl;
+
+	for_each_sched_entity(se) {
+		long w, W;
+
+		tg = se->my_q->tg;
+
+		/*
+		 * W = @wg + \Sum rw_j
+		 */
+		W = wg + calc_tg_weight(tg, se->my_q);
+
+		/*
+		 * w = rw_i + @wl
+		 */
+		w = se->my_q->load.weight + wl;
+
+		/*
+		 * wl = S * s'_i; see (2)
+		 */
+		if (W > 0 && w < W)
+			wl = (w * (long)tg->shares) / W;
+		else
+			wl = tg->shares;
+
+		/*
+		 * Per the above, wl is the new se->load.weight value; since
+		 * those are clipped to [MIN_SHARES, ...) do so now. See
+		 * calc_cfs_shares().
+		 */
+		if (wl < MIN_SHARES)
+			wl = MIN_SHARES;
+
+		/*
+		 * wl = dw_i = S * (s'_i - s_i); see (3)
+		 */
+		wl -= se->load.weight;
+
+		/*
+		 * Recursively apply this logic to all parent groups to compute
+		 * the final effective load change on the root group. Since
+		 * only the @tg group gets extra weight, all parent groups can
+		 * only redistribute existing shares. @wl is the shift in shares
+		 * resulting from this level per the above.
+		 */
+		wg = 0;
+	}
+
+	return wl;
+}
+#else
+
+static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
+{
+	return wl;
+}
+
+#endif
+
+static int wake_wide(struct task_struct *p)
+{
+	int factor = this_cpu_read(sd_llc_size);
+
+	/*
+	 * Yeah, it's the switching-frequency, could means many wakee or
+	 * rapidly switch, use factor here will just help to automatically
+	 * adjust the loose-degree, so bigger node will lead to more pull.
+	 */
+	if (p->wakee_flips > factor) {
+		/*
+		 * wakee is somewhat hot, it needs certain amount of cpu
+		 * resource, so if waker is far more hot, prefer to leave
+		 * it alone.
+		 */
+		if (current->wakee_flips > (factor * p->wakee_flips))
+			return 1;
+	}
+
+	return 0;
+}
+
+static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
+{
+	s64 this_load, load;
+	s64 this_eff_load, prev_eff_load;
+	int idx, this_cpu, prev_cpu;
+	struct task_group *tg;
+	unsigned long weight;
+	int balanced;
+
+	/*
+	 * If we wake multiple tasks be careful to not bounce
+	 * ourselves around too much.
+	 */
+	if (wake_wide(p))
+		return 0;
+
+	idx	  = sd->wake_idx;
+	this_cpu  = smp_processor_id();
+	prev_cpu  = task_cpu(p);
+	load	  = source_load(prev_cpu, idx);
+	this_load = target_load(this_cpu, idx);
+
+	/*
+	 * If sync wakeup then subtract the (maximum possible)
+	 * effect of the currently running task from the load
+	 * of the current CPU:
+	 */
+	if (sync) {
+		tg = task_group(current);
+		weight = current->se.load.weight;
+
+		this_load += effective_load(tg, this_cpu, -weight, -weight);
+		load += effective_load(tg, prev_cpu, 0, -weight);
+	}
+
+	tg = task_group(p);
+	weight = p->se.load.weight;
+
+	/*
+	 * In low-load situations, where prev_cpu is idle and this_cpu is idle
+	 * due to the sync cause above having dropped this_load to 0, we'll
+	 * always have an imbalance, but there's really nothing you can do
+	 * about that, so that's good too.
+	 *
+	 * Otherwise check if either cpus are near enough in load to allow this
+	 * task to be woken on this_cpu.
+	 */
+	this_eff_load = 100;
+	this_eff_load *= capacity_of(prev_cpu);
+
+	prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2;
+	prev_eff_load *= capacity_of(this_cpu);
+
+	if (this_load > 0) {
+		this_eff_load *= this_load +
+			effective_load(tg, this_cpu, weight, weight);
+
+		prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight);
+	}
+
+	balanced = this_eff_load <= prev_eff_load;
+
+	schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
+
+	if (!balanced)
+		return 0;
+
+	schedstat_inc(sd, ttwu_move_affine);
+	schedstat_inc(p, se.statistics.nr_wakeups_affine);
+
+	return 1;
+}
+
+/*
+ * find_idlest_group finds and returns the least busy CPU group within the
+ * domain.
+ */
+static struct sched_group *
+find_idlest_group(struct sched_domain *sd, struct task_struct *p,
+		  int this_cpu, int sd_flag)
+{
+	struct sched_group *idlest = NULL, *group = sd->groups;
+	unsigned long min_load = ULONG_MAX, this_load = 0;
+	int load_idx = sd->forkexec_idx;
+	int imbalance = 100 + (sd->imbalance_pct-100)/2;
+
+	if (sd_flag & SD_BALANCE_WAKE)
+		load_idx = sd->wake_idx;
+
+	do {
+		unsigned long load, avg_load;
+		int local_group;
+		int i;
+
+		/* Skip over this group if it has no CPUs allowed */
+		if (!cpumask_intersects(sched_group_cpus(group),
+					tsk_cpus_allowed(p)))
+			continue;
+
+		local_group = cpumask_test_cpu(this_cpu,
+					       sched_group_cpus(group));
+
+		/* Tally up the load of all CPUs in the group */
+		avg_load = 0;
+
+		for_each_cpu(i, sched_group_cpus(group)) {
+			/* Bias balancing toward cpus of our domain */
+			if (local_group)
+				load = source_load(i, load_idx);
+			else
+				load = target_load(i, load_idx);
+
+			avg_load += load;
+		}
+
+		/* Adjust by relative CPU capacity of the group */
+		avg_load = (avg_load * SCHED_CAPACITY_SCALE) / group->sgc->capacity;
+
+		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;
+	unsigned int min_exit_latency = UINT_MAX;
+	u64 latest_idle_timestamp = 0;
+	int least_loaded_cpu = this_cpu;
+	int shallowest_idle_cpu = -1;
+	int i;
+
+	/* Traverse only the allowed CPUs */
+	for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) {
+		if (idle_cpu(i)) {
+			struct rq *rq = cpu_rq(i);
+			struct cpuidle_state *idle = idle_get_state(rq);
+			if (idle && idle->exit_latency < min_exit_latency) {
+				/*
+				 * We give priority to a CPU whose idle state
+				 * has the smallest exit latency irrespective
+				 * of any idle timestamp.
+				 */
+				min_exit_latency = idle->exit_latency;
+				latest_idle_timestamp = rq->idle_stamp;
+				shallowest_idle_cpu = i;
+			} else if ((!idle || idle->exit_latency == min_exit_latency) &&
+				   rq->idle_stamp > latest_idle_timestamp) {
+				/*
+				 * If equal or no active idle state, then
+				 * the most recently idled CPU might have
+				 * a warmer cache.
+				 */
+				latest_idle_timestamp = rq->idle_stamp;
+				shallowest_idle_cpu = i;
+			}
+		} else if (shallowest_idle_cpu == -1) {
+			load = weighted_cpuload(i);
+			if (load < min_load || (load == min_load && i == this_cpu)) {
+				min_load = load;
+				least_loaded_cpu = i;
+			}
+		}
+	}
+
+	return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu;
+}
+
+/*
+ * Try and locate an idle CPU in the sched_domain.
+ */
+static int select_idle_sibling(struct task_struct *p, int target)
+{
+	struct sched_domain *sd;
+	struct sched_group *sg;
+	int i = task_cpu(p);
+
+	if (idle_cpu(target))
+		return target;
+
+	/*
+	 * If the prevous cpu is cache affine and idle, don't be stupid.
+	 */
+	if (i != target && cpus_share_cache(i, target) && idle_cpu(i))
+		return i;
+
+	/*
+	 * Otherwise, iterate the domains and find an elegible idle cpu.
+	 */
+	sd = rcu_dereference(per_cpu(sd_llc, target));
+	for_each_lower_domain(sd) {
+		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 (i == target || !idle_cpu(i))
+					goto next;
+			}
+
+			target = cpumask_first_and(sched_group_cpus(sg),
+					tsk_cpus_allowed(p));
+			goto done;
+next:
+			sg = sg->next;
+		} while (sg != sd->groups);
+	}
+done:
+	return target;
+}
+/*
+ * get_cpu_usage returns the amount of capacity of a CPU that is used by CFS
+ * tasks. The unit of the return value must be the one of capacity so we can
+ * compare the usage with the capacity of the CPU that is available for CFS
+ * task (ie cpu_capacity).
+ * cfs.utilization_load_avg is the sum of running time of runnable tasks on a
+ * CPU. It represents the amount of utilization of a CPU in the range
+ * [0..SCHED_LOAD_SCALE].  The usage of a CPU can't be higher than the full
+ * capacity of the CPU because it's about the running time on this CPU.
+ * Nevertheless, cfs.utilization_load_avg can be higher than SCHED_LOAD_SCALE
+ * because of unfortunate rounding in avg_period and running_load_avg or just
+ * after migrating tasks until the average stabilizes with the new running
+ * time. So we need to check that the usage stays into the range
+ * [0..cpu_capacity_orig] and cap if necessary.
+ * Without capping the usage, a group could be seen as overloaded (CPU0 usage
+ * at 121% + CPU1 usage at 80%) whereas CPU1 has 20% of available capacity
+ */
+static int get_cpu_usage(int cpu)
+{
+	unsigned long usage = cpu_rq(cpu)->cfs.utilization_load_avg;
+	unsigned long capacity = capacity_orig_of(cpu);
+
+	if (usage >= SCHED_LOAD_SCALE)
+		return capacity;
+
+	return (usage * capacity) >> SCHED_LOAD_SHIFT;
+}
+
+/*
+ * select_task_rq_fair: Select target runqueue for the waking task in domains
+ * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE,
+ * SD_BALANCE_FORK, or SD_BALANCE_EXEC.
+ *
+ * Balances load by selecting the idlest cpu in the idlest group, or under
+ * certain conditions an idle sibling cpu if the domain has SD_WAKE_AFFINE set.
+ *
+ * Returns the target cpu number.
+ *
+ * preempt must be disabled.
+ */
+static int
+select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags)
+{
+	struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
+	int cpu = smp_processor_id();
+	int new_cpu = cpu;
+	int want_affine = 0;
+	int sync = wake_flags & WF_SYNC;
+
+	if (sd_flag & SD_BALANCE_WAKE)
+		want_affine = cpumask_test_cpu(cpu, tsk_cpus_allowed(p));
+
+	rcu_read_lock();
+	for_each_domain(cpu, tmp) {
+		if (!(tmp->flags & SD_LOAD_BALANCE))
+			continue;
+
+		/*
+		 * If both cpu and prev_cpu are part of this domain,
+		 * cpu is a valid SD_WAKE_AFFINE target.
+		 */
+		if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
+		    cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
+			affine_sd = tmp;
+			break;
+		}
+
+		if (tmp->flags & sd_flag)
+			sd = tmp;
+	}
+
+	if (affine_sd && cpu != prev_cpu && wake_affine(affine_sd, p, sync))
+		prev_cpu = cpu;
+
+	if (sd_flag & SD_BALANCE_WAKE) {
+		new_cpu = select_idle_sibling(p, prev_cpu);
+		goto unlock;
+	}
+
+	while (sd) {
+		struct sched_group *group;
+		int weight;
+
+		if (!(sd->flags & sd_flag)) {
+			sd = sd->child;
+			continue;
+		}
+
+		group = find_idlest_group(sd, p, cpu, sd_flag);
+		if (!group) {
+			sd = sd->child;
+			continue;
+		}
+
+		new_cpu = find_idlest_cpu(group, p, cpu);
+		if (new_cpu == -1 || new_cpu == cpu) {
+			/* Now try balancing at a lower domain level of cpu */
+			sd = sd->child;
+			continue;
+		}
+
+		/* Now try balancing at a lower domain level of new_cpu */
+		cpu = new_cpu;
+		weight = sd->span_weight;
+		sd = NULL;
+		for_each_domain(cpu, tmp) {
+			if (weight <= tmp->span_weight)
+				break;
+			if (tmp->flags & sd_flag)
+				sd = tmp;
+		}
+		/* while loop will break here if sd == NULL */
+	}
+unlock:
+	rcu_read_unlock();
+
+	return new_cpu;
+}
+
+/*
+ * Called immediately before a task is migrated to a new cpu; task_cpu(p) and
+ * cfs_rq_of(p) references at time of call are still valid and identify the
+ * previous cpu.  However, the caller only guarantees p->pi_lock is held; no
+ * other assumptions, including the state of rq->lock, should be made.
+ */
+static void
+migrate_task_rq_fair(struct task_struct *p, int next_cpu)
+{
+	struct sched_entity *se = &p->se;
+	struct cfs_rq *cfs_rq = cfs_rq_of(se);
+
+	/*
+	 * Load tracking: accumulate removed load so that it can be processed
+	 * when we next update owning cfs_rq under rq->lock.  Tasks contribute
+	 * to blocked load iff they have a positive decay-count.  It can never
+	 * be negative here since on-rq tasks have decay-count == 0.
+	 */
+	if (se->avg.decay_count) {
+		se->avg.decay_count = -__synchronize_entity_decay(se);
+		atomic_long_add(se->avg.load_avg_contrib,
+						&cfs_rq->removed_load);
+	}
+
+	/* We have migrated, no longer consider this task hot */
+	se->exec_start = 0;
+}
+#endif /* CONFIG_SMP */
+
+static unsigned long
+wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
+{
+	unsigned long gran = sysctl_sched_wakeup_granularity;
+
+	/*
+	 * Since its curr running now, convert the gran from real-time
+	 * to virtual-time in his units.
+	 *
+	 * By using 'se' instead of 'curr' we penalize light tasks, so
+	 * they get preempted easier. That is, if 'se' < 'curr' then
+	 * the resulting gran will be larger, therefore penalizing the
+	 * lighter, if otoh 'se' > 'curr' then the resulting gran will
+	 * be smaller, again penalizing the lighter task.
+	 *
+	 * This is especially important for buddies when the leftmost
+	 * task is higher priority than the buddy.
+	 */
+	return calc_delta_fair(gran, se);
+}
+
+/*
+ * Should 'se' preempt 'curr'.
+ *
+ *             |s1
+ *        |s2
+ *   |s3
+ *         g
+ *      |<--->|c
+ *
+ *  w(c, s1) = -1
+ *  w(c, s2) =  0
+ *  w(c, s3) =  1
+ *
+ */
+static int
+wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
+{
+	s64 gran, vdiff = curr->vruntime - se->vruntime;
+
+	if (vdiff <= 0)
+		return -1;
+
+	gran = wakeup_gran(curr, se);
+	if (vdiff > gran)
+		return 1;
+
+	return 0;
+}
+
+static void set_last_buddy(struct sched_entity *se)
+{
+	if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
+		return;
+
+	for_each_sched_entity(se)
+		cfs_rq_of(se)->last = se;
+}
+
+static void set_next_buddy(struct sched_entity *se)
+{
+	if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
+		return;
+
+	for_each_sched_entity(se)
+		cfs_rq_of(se)->next = se;
+}
+
+static void set_skip_buddy(struct sched_entity *se)
+{
+	for_each_sched_entity(se)
+		cfs_rq_of(se)->skip = se;
+}
+
+/*
+ * Preempt the current task with a newly woken task if needed:
+ */
+static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
+{
+	struct task_struct *curr = rq->curr;
+	struct sched_entity *se = &curr->se, *pse = &p->se;
+	struct cfs_rq *cfs_rq = task_cfs_rq(curr);
+	int scale = cfs_rq->nr_running >= sched_nr_latency;
+	int next_buddy_marked = 0;
+
+	if (unlikely(se == pse))
+		return;
+
+	/*
+	 * This is possible from callers such as attach_tasks(), in which we
+	 * unconditionally check_prempt_curr() after an enqueue (which may have
+	 * lead to a throttle).  This both saves work and prevents false
+	 * next-buddy nomination below.
+	 */
+	if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
+		return;
+
+	if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
+		set_next_buddy(pse);
+		next_buddy_marked = 1;
+	}
+
+	/*
+	 * We can come here with TIF_NEED_RESCHED already set from new task
+	 * wake up path.
+	 *
+	 * Note: this also catches the edge-case of curr being in a throttled
+	 * group (e.g. via set_curr_task), since update_curr() (in the
+	 * enqueue of curr) will have resulted in resched being set.  This
+	 * prevents us from potentially nominating it as a false LAST_BUDDY
+	 * below.
+	 */
+	if (test_tsk_need_resched(curr))
+		return;
+
+	/* Idle tasks are by definition preempted by non-idle tasks. */
+	if (unlikely(curr->policy == SCHED_IDLE) &&
+	    likely(p->policy != SCHED_IDLE))
+		goto preempt;
+
+	/*
+	 * Batch and idle tasks do not preempt non-idle tasks (their preemption
+	 * is driven by the tick):
+	 */
+	if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
+		return;
+
+	find_matching_se(&se, &pse);
+	update_curr(cfs_rq_of(se));
+	BUG_ON(!pse);
+	if (wakeup_preempt_entity(se, pse) == 1) {
+		/*
+		 * Bias pick_next to pick the sched entity that is
+		 * triggering this preemption.
+		 */
+		if (!next_buddy_marked)
+			set_next_buddy(pse);
+		goto preempt;
+	}
+
+	return;
+
+preempt:
+	resched_curr(rq);
+	/*
+	 * Only set the backward buddy when the current task is still
+	 * on the rq. This can happen when a wakeup gets interleaved
+	 * with schedule on the ->pre_schedule() or idle_balance()
+	 * point, either of which can * drop the rq lock.
+	 *
+	 * Also, during early boot the idle thread is in the fair class,
+	 * for obvious reasons its a bad idea to schedule back to it.
+	 */
+	if (unlikely(!se->on_rq || curr == rq->idle))
+		return;
+
+	if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
+		set_last_buddy(se);
+}
+
+static struct task_struct *
+pick_next_task_fair(struct rq *rq, struct task_struct *prev)
+{
+	struct cfs_rq *cfs_rq = &rq->cfs;
+	struct sched_entity *se;
+	struct task_struct *p;
+	int new_tasks;
+
+again:
+#ifdef CONFIG_FAIR_GROUP_SCHED
+	if (!cfs_rq->nr_running)
+		goto idle;
+
+	if (prev->sched_class != &fair_sched_class)
+		goto simple;
+
+	/*
+	 * Because of the set_next_buddy() in dequeue_task_fair() it is rather
+	 * likely that a next task is from the same cgroup as the current.
+	 *
+	 * Therefore attempt to avoid putting and setting the entire cgroup
+	 * hierarchy, only change the part that actually changes.
+	 */
+
+	do {
+		struct sched_entity *curr = cfs_rq->curr;
+
+		/*
+		 * Since we got here without doing put_prev_entity() we also
+		 * have to consider cfs_rq->curr. If it is still a runnable
+		 * entity, update_curr() will update its vruntime, otherwise
+		 * forget we've ever seen it.
+		 */
+		if (curr && curr->on_rq)
+			update_curr(cfs_rq);
+		else
+			curr = NULL;
+
+		/*
+		 * This call to check_cfs_rq_runtime() will do the throttle and
+		 * dequeue its entity in the parent(s). Therefore the 'simple'
+		 * nr_running test will indeed be correct.
+		 */
+		if (unlikely(check_cfs_rq_runtime(cfs_rq)))
+			goto simple;
+
+		se = pick_next_entity(cfs_rq, curr);
+		cfs_rq = group_cfs_rq(se);
+	} while (cfs_rq);
+
+	p = task_of(se);
+
+	/*
+	 * Since we haven't yet done put_prev_entity and if the selected task
+	 * is a different task than we started out with, try and touch the
+	 * least amount of cfs_rqs.
+	 */
+	if (prev != p) {
+		struct sched_entity *pse = &prev->se;
+
+		while (!(cfs_rq = is_same_group(se, pse))) {
+			int se_depth = se->depth;
+			int pse_depth = pse->depth;
+
+			if (se_depth <= pse_depth) {
+				put_prev_entity(cfs_rq_of(pse), pse);
+				pse = parent_entity(pse);
+			}
+			if (se_depth >= pse_depth) {
+				set_next_entity(cfs_rq_of(se), se);
+				se = parent_entity(se);
+			}
+		}
+
+		put_prev_entity(cfs_rq, pse);
+		set_next_entity(cfs_rq, se);
+	}
+
+	if (hrtick_enabled(rq))
+		hrtick_start_fair(rq, p);
+
+	return p;
+simple:
+	cfs_rq = &rq->cfs;
+#endif
+
+	if (!cfs_rq->nr_running)
+		goto idle;
+
+	put_prev_task(rq, prev);
+
+	do {
+		se = pick_next_entity(cfs_rq, NULL);
+		set_next_entity(cfs_rq, se);
+		cfs_rq = group_cfs_rq(se);
+	} while (cfs_rq);
+
+	p = task_of(se);
+
+	if (hrtick_enabled(rq))
+		hrtick_start_fair(rq, p);
+
+	return p;
+
+idle:
+	new_tasks = idle_balance(rq);
+	/*
+	 * Because idle_balance() releases (and re-acquires) rq->lock, it is
+	 * possible for any higher priority task to appear. In that case we
+	 * must re-start the pick_next_entity() loop.
+	 */
+	if (new_tasks < 0)
+		return RETRY_TASK;
+
+	if (new_tasks > 0)
+		goto again;
+
+	return NULL;
+}
+
+/*
+ * Account for a descheduled task:
+ */
+static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
+{
+	struct sched_entity *se = &prev->se;
+	struct cfs_rq *cfs_rq;
+
+	for_each_sched_entity(se) {
+		cfs_rq = cfs_rq_of(se);
+		put_prev_entity(cfs_rq, se);
+	}
+}
+
+/*
+ * sched_yield() is very simple
+ *
+ * The magic of dealing with the ->skip buddy is in pick_next_entity.
+ */
+static void yield_task_fair(struct rq *rq)
+{
+	struct task_struct *curr = rq->curr;
+	struct cfs_rq *cfs_rq = task_cfs_rq(curr);
+	struct sched_entity *se = &curr->se;
+
+	/*
+	 * Are we the only task in the tree?
+	 */
+	if (unlikely(rq->nr_running == 1))
+		return;
+
+	clear_buddies(cfs_rq, se);
+
+	if (curr->policy != SCHED_BATCH) {
+		update_rq_clock(rq);
+		/*
+		 * Update run-time statistics of the 'current'.
+		 */
+		update_curr(cfs_rq);
+		/*
+		 * Tell update_rq_clock() that we've just updated,
+		 * so we don't do microscopic update in schedule()
+		 * and double the fastpath cost.
+		 */
+		rq_clock_skip_update(rq, true);
+	}
+
+	set_skip_buddy(se);
+}
+
+static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt)
+{
+	struct sched_entity *se = &p->se;
+
+	/* throttled hierarchies are not runnable */
+	if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
+		return false;
+
+	/* Tell the scheduler that we'd really like pse to run next. */
+	set_next_buddy(se);
+
+	yield_task_fair(rq);
+
+	return true;
+}
+
+#ifdef CONFIG_SMP
+/**************************************************
+ * Fair scheduling class load-balancing methods.
+ *
+ * BASICS
+ *
+ * The purpose of load-balancing is to achieve the same basic fairness the
+ * per-cpu scheduler provides, namely provide a proportional amount of compute
+ * time to each task. This is expressed in the following equation:
+ *
+ *   W_i,n/P_i == W_j,n/P_j for all i,j                               (1)
+ *
+ * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight
+ * W_i,0 is defined as:
+ *
+ *   W_i,0 = \Sum_j w_i,j                                             (2)
+ *
+ * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight
+ * is derived from the nice value as per prio_to_weight[].
+ *
+ * The weight average is an exponential decay average of the instantaneous
+ * weight:
+ *
+ *   W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0               (3)
+ *
+ * C_i is the compute capacity of cpu i, typically it is the
+ * fraction of 'recent' time available for SCHED_OTHER task execution. But it
+ * can also include other factors [XXX].
+ *
+ * To achieve this balance we define a measure of imbalance which follows
+ * directly from (1):
+ *
+ *   imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j }    (4)
+ *
+ * We them move tasks around to minimize the imbalance. In the continuous
+ * function space it is obvious this converges, in the discrete case we get
+ * a few fun cases generally called infeasible weight scenarios.
+ *
+ * [XXX expand on:
+ *     - infeasible weights;
+ *     - local vs global optima in the discrete case. ]
+ *
+ *
+ * SCHED DOMAINS
+ *
+ * In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
+ * for all i,j solution, we create a tree of cpus that follows the hardware
+ * topology where each level pairs two lower groups (or better). This results
+ * in O(log n) layers. Furthermore we reduce the number of cpus going up the
+ * tree to only the first of the previous level and we decrease the frequency
+ * of load-balance at each level inv. proportional to the number of cpus in
+ * the groups.
+ *
+ * This yields:
+ *
+ *     log_2 n     1     n
+ *   \Sum       { --- * --- * 2^i } = O(n)                            (5)
+ *     i = 0      2^i   2^i
+ *                               `- size of each group
+ *         |         |     `- number of cpus doing load-balance
+ *         |         `- freq
+ *         `- sum over all levels
+ *
+ * Coupled with a limit on how many tasks we can migrate every balance pass,
+ * this makes (5) the runtime complexity of the balancer.
+ *
+ * An important property here is that each CPU is still (indirectly) connected
+ * to every other cpu in at most O(log n) steps:
+ *
+ * The adjacency matrix of the resulting graph is given by:
+ *
+ *             log_2 n     
+ *   A_i,j = \Union     (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1)  (6)
+ *             k = 0
+ *
+ * And you'll find that:
+ *
+ *   A^(log_2 n)_i,j != 0  for all i,j                                (7)
+ *
+ * Showing there's indeed a path between every cpu in at most O(log n) steps.
+ * The task movement gives a factor of O(m), giving a convergence complexity
+ * of:
+ *
+ *   O(nm log n),  n := nr_cpus, m := nr_tasks                        (8)
+ *
+ *
+ * WORK CONSERVING
+ *
+ * In order to avoid CPUs going idle while there's still work to do, new idle
+ * balancing is more aggressive and has the newly idle cpu iterate up the domain
+ * tree itself instead of relying on other CPUs to bring it work.
+ *
+ * This adds some complexity to both (5) and (8) but it reduces the total idle
+ * time.
+ *
+ * [XXX more?]
+ *
+ *
+ * CGROUPS
+ *
+ * Cgroups make a horror show out of (2), instead of a simple sum we get:
+ *
+ *                                s_k,i
+ *   W_i,0 = \Sum_j \Prod_k w_k * -----                               (9)
+ *                                 S_k
+ *
+ * Where
+ *
+ *   s_k,i = \Sum_j w_i,j,k  and  S_k = \Sum_i s_k,i                 (10)
+ *
+ * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i.
+ *
+ * The big problem is S_k, its a global sum needed to compute a local (W_i)
+ * property.
+ *
+ * [XXX write more on how we solve this.. _after_ merging pjt's patches that
+ *      rewrite all of this once again.]
+ */ 
+
+static unsigned long __read_mostly max_load_balance_interval = HZ/10;
+
+enum fbq_type { regular, remote, all };
+
+#define LBF_ALL_PINNED	0x01
+#define LBF_NEED_BREAK	0x02
+#define LBF_DST_PINNED  0x04
+#define LBF_SOME_PINNED	0x08
+
+struct lb_env {
+	struct sched_domain	*sd;
+
+	struct rq		*src_rq;
+	int			src_cpu;
+
+	int			dst_cpu;
+	struct rq		*dst_rq;
+
+	struct cpumask		*dst_grpmask;
+	int			new_dst_cpu;
+	enum cpu_idle_type	idle;
+	long			imbalance;
+	/* The set of CPUs under consideration for load-balancing */
+	struct cpumask		*cpus;
+
+	unsigned int		flags;
+
+	unsigned int		loop;
+	unsigned int		loop_break;
+	unsigned int		loop_max;
+
+	enum fbq_type		fbq_type;
+	struct list_head	tasks;
+};
+
+/*
+ * Is this task likely cache-hot:
+ */
+static int task_hot(struct task_struct *p, struct lb_env *env)
+{
+	s64 delta;
+
+	lockdep_assert_held(&env->src_rq->lock);
+
+	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) && env->dst_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 = rq_clock_task(env->src_rq) - p->se.exec_start;
+
+	return delta < (s64)sysctl_sched_migration_cost;
+}
+
+#ifdef CONFIG_NUMA_BALANCING
+/* Returns true if the destination node has incurred more faults */
+static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env)
+{
+	struct numa_group *numa_group = rcu_dereference(p->numa_group);
+	int src_nid, dst_nid;
+
+	if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults ||
+	    !(env->sd->flags & SD_NUMA)) {
+		return false;
+	}
+
+	src_nid = cpu_to_node(env->src_cpu);
+	dst_nid = cpu_to_node(env->dst_cpu);
+
+	if (src_nid == dst_nid)
+		return false;
+
+	if (numa_group) {
+		/* Task is already in the group's interleave set. */
+		if (node_isset(src_nid, numa_group->active_nodes))
+			return false;
+
+		/* Task is moving into the group's interleave set. */
+		if (node_isset(dst_nid, numa_group->active_nodes))
+			return true;
+
+		return group_faults(p, dst_nid) > group_faults(p, src_nid);
+	}
+
+	/* Encourage migration to the preferred node. */
+	if (dst_nid == p->numa_preferred_nid)
+		return true;
+
+	return task_faults(p, dst_nid) > task_faults(p, src_nid);
+}
+
+
+static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
+{
+	struct numa_group *numa_group = rcu_dereference(p->numa_group);
+	int src_nid, dst_nid;
+
+	if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER))
+		return false;
+
+	if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
+		return false;
+
+	src_nid = cpu_to_node(env->src_cpu);
+	dst_nid = cpu_to_node(env->dst_cpu);
+
+	if (src_nid == dst_nid)
+		return false;
+
+	if (numa_group) {
+		/* Task is moving within/into the group's interleave set. */
+		if (node_isset(dst_nid, numa_group->active_nodes))
+			return false;
+
+		/* Task is moving out of the group's interleave set. */
+		if (node_isset(src_nid, numa_group->active_nodes))
+			return true;
+
+		return group_faults(p, dst_nid) < group_faults(p, src_nid);
+	}
+
+	/* Migrating away from the preferred node is always bad. */
+	if (src_nid == p->numa_preferred_nid)
+		return true;
+
+	return task_faults(p, dst_nid) < task_faults(p, src_nid);
+}
+
+#else
+static inline bool migrate_improves_locality(struct task_struct *p,
+					     struct lb_env *env)
+{
+	return false;
+}
+
+static inline bool migrate_degrades_locality(struct task_struct *p,
+					     struct lb_env *env)
+{
+	return false;
+}
+#endif
+
+/*
+ * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
+ */
+static
+int can_migrate_task(struct task_struct *p, struct lb_env *env)
+{
+	int tsk_cache_hot = 0;
+
+	lockdep_assert_held(&env->src_rq->lock);
+
+	/*
+	 * We do not migrate tasks that are:
+	 * 1) throttled_lb_pair, or
+	 * 2) cannot be migrated to this CPU due to cpus_allowed, or
+	 * 3) running (obviously), or
+	 * 4) are cache-hot on their current CPU.
+	 */
+	if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
+		return 0;
+
+	if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
+		int cpu;
+
+		schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
+
+		env->flags |= LBF_SOME_PINNED;
+
+		/*
+		 * 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_DST_PINNED))
+			return 0;
+
+		/* Prevent to re-select dst_cpu via env's cpus */
+		for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) {
+			if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) {
+				env->flags |= LBF_DST_PINNED;
+				env->new_dst_cpu = cpu;
+				break;
+			}
+		}
+
+		return 0;
+	}
+
+	/* Record that we found atleast one task that could run on dst_cpu */
+	env->flags &= ~LBF_ALL_PINNED;
+
+	if (task_running(env->src_rq, p)) {
+		schedstat_inc(p, se.statistics.nr_failed_migrations_running);
+		return 0;
+	}
+
+	/*
+	 * Aggressive migration if:
+	 * 1) destination numa is preferred
+	 * 2) task is cache cold, or
+	 * 3) too many balance attempts have failed.
+	 */
+	tsk_cache_hot = task_hot(p, env);
+	if (!tsk_cache_hot)
+		tsk_cache_hot = migrate_degrades_locality(p, env);
+
+	if (migrate_improves_locality(p, env) || !tsk_cache_hot ||
+	    env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
+		if (tsk_cache_hot) {
+			schedstat_inc(env->sd, lb_hot_gained[env->idle]);
+			schedstat_inc(p, se.statistics.nr_forced_migrations);
+		}
+		return 1;
+	}
+
+	schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
+	return 0;
+}
+
+/*
+ * detach_task() -- detach the task for the migration specified in env
+ */
+static void detach_task(struct task_struct *p, struct lb_env *env)
+{
+	lockdep_assert_held(&env->src_rq->lock);
+
+	deactivate_task(env->src_rq, p, 0);
+	p->on_rq = TASK_ON_RQ_MIGRATING;
+	set_task_cpu(p, env->dst_cpu);
+}
+
+/*
+ * detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as
+ * part of active balancing operations within "domain".
+ *
+ * Returns a task if successful and NULL otherwise.
+ */
+static struct task_struct *detach_one_task(struct lb_env *env)
+{
+	struct task_struct *p, *n;
+
+	lockdep_assert_held(&env->src_rq->lock);
+
+	list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
+		if (!can_migrate_task(p, env))
+			continue;
+
+		detach_task(p, env);
+
+		/*
+		 * Right now, this is only the second place where
+		 * lb_gained[env->idle] is updated (other is detach_tasks)
+		 * so we can safely collect stats here rather than
+		 * inside detach_tasks().
+		 */
+		schedstat_inc(env->sd, lb_gained[env->idle]);
+		return p;
+	}
+	return NULL;
+}
+
+static const unsigned int sched_nr_migrate_break = 32;
+
+/*
+ * detach_tasks() -- tries to detach up to imbalance weighted load from
+ * busiest_rq, as part of a balancing operation within domain "sd".
+ *
+ * Returns number of detached tasks if successful and 0 otherwise.
+ */
+static int detach_tasks(struct lb_env *env)
+{
+	struct list_head *tasks = &env->src_rq->cfs_tasks;
+	struct task_struct *p;
+	unsigned long load;
+	int detached = 0;
+
+	lockdep_assert_held(&env->src_rq->lock);
+
+	if (env->imbalance <= 0)
+		return 0;
+
+	while (!list_empty(tasks)) {
+		p = list_first_entry(tasks, struct task_struct, se.group_node);
+
+		env->loop++;
+		/* We've more or less seen every task there is, call it quits */
+		if (env->loop > env->loop_max)
+			break;
+
+		/* take a breather every nr_migrate tasks */
+		if (env->loop > env->loop_break) {
+			env->loop_break += sched_nr_migrate_break;
+			env->flags |= LBF_NEED_BREAK;
+			break;
+		}
+
+		if (!can_migrate_task(p, env))
+			goto next;
+
+		load = task_h_load(p);
+
+		if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed)
+			goto next;
+
+		if ((load / 2) > env->imbalance)
+			goto next;
+
+		detach_task(p, env);
+		list_add(&p->se.group_node, &env->tasks);
+
+		detached++;
+		env->imbalance -= load;
+
+#ifdef CONFIG_PREEMPT
+		/*
+		 * NEWIDLE balancing is a source of latency, so preemptible
+		 * kernels will stop after the first task is detached to minimize
+		 * the critical section.
+		 */
+		if (env->idle == CPU_NEWLY_IDLE)
+			break;
+#endif
+
+		/*
+		 * We only want to steal up to the prescribed amount of
+		 * weighted load.
+		 */
+		if (env->imbalance <= 0)
+			break;
+
+		continue;
+next:
+		list_move_tail(&p->se.group_node, tasks);
+	}
+
+	/*
+	 * Right now, this is one of only two places we collect this stat
+	 * so we can safely collect detach_one_task() stats here rather
+	 * than inside detach_one_task().
+	 */
+	schedstat_add(env->sd, lb_gained[env->idle], detached);
+
+	return detached;
+}
+
+/*
+ * attach_task() -- attach the task detached by detach_task() to its new rq.
+ */
+static void attach_task(struct rq *rq, struct task_struct *p)
+{
+	lockdep_assert_held(&rq->lock);
+
+	BUG_ON(task_rq(p) != rq);
+	p->on_rq = TASK_ON_RQ_QUEUED;
+	activate_task(rq, p, 0);
+	check_preempt_curr(rq, p, 0);
+}
+
+/*
+ * attach_one_task() -- attaches the task returned from detach_one_task() to
+ * its new rq.
+ */
+static void attach_one_task(struct rq *rq, struct task_struct *p)
+{
+	raw_spin_lock(&rq->lock);
+	attach_task(rq, p);
+	raw_spin_unlock(&rq->lock);
+}
+
+/*
+ * attach_tasks() -- attaches all tasks detached by detach_tasks() to their
+ * new rq.
+ */
+static void attach_tasks(struct lb_env *env)
+{
+	struct list_head *tasks = &env->tasks;
+	struct task_struct *p;
+
+	raw_spin_lock(&env->dst_rq->lock);
+
+	while (!list_empty(tasks)) {
+		p = list_first_entry(tasks, struct task_struct, se.group_node);
+		list_del_init(&p->se.group_node);
+
+		attach_task(env->dst_rq, p);
+	}
+
+	raw_spin_unlock(&env->dst_rq->lock);
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+/*
+ * update tg->load_weight by folding this cpu's load_avg
+ */
+static void __update_blocked_averages_cpu(struct task_group *tg, int cpu)
+{
+	struct sched_entity *se = tg->se[cpu];
+	struct cfs_rq *cfs_rq = tg->cfs_rq[cpu];
+
+	/* throttled entities do not contribute to load */
+	if (throttled_hierarchy(cfs_rq))
+		return;
+
+	update_cfs_rq_blocked_load(cfs_rq, 1);
+
+	if (se) {
+		update_entity_load_avg(se, 1);
+		/*
+		 * We pivot on our runnable average having decayed to zero for
+		 * list removal.  This generally implies that all our children
+		 * have also been removed (modulo rounding error or bandwidth
+		 * control); however, such cases are rare and we can fix these
+		 * at enqueue.
+		 *
+		 * TODO: fix up out-of-order children on enqueue.
+		 */
+		if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running)
+			list_del_leaf_cfs_rq(cfs_rq);
+	} else {
+		struct rq *rq = rq_of(cfs_rq);
+		update_rq_runnable_avg(rq, rq->nr_running);
+	}
+}
+
+static void update_blocked_averages(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	struct cfs_rq *cfs_rq;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&rq->lock, flags);
+	update_rq_clock(rq);
+	/*
+	 * Iterates the task_group tree in a bottom up fashion, see
+	 * list_add_leaf_cfs_rq() for details.
+	 */
+	for_each_leaf_cfs_rq(rq, cfs_rq) {
+		/*
+		 * Note: We may want to consider periodically releasing
+		 * rq->lock about these updates so that creating many task
+		 * groups does not result in continually extending hold time.
+		 */
+		__update_blocked_averages_cpu(cfs_rq->tg, rq->cpu);
+	}
+
+	raw_spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+/*
+ * Compute the hierarchical load factor for cfs_rq and all its ascendants.
+ * 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 void update_cfs_rq_h_load(struct cfs_rq *cfs_rq)
+{
+	struct rq *rq = rq_of(cfs_rq);
+	struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)];
+	unsigned long now = jiffies;
+	unsigned long load;
+
+	if (cfs_rq->last_h_load_update == now)
+		return;
+
+	cfs_rq->h_load_next = NULL;
+	for_each_sched_entity(se) {
+		cfs_rq = cfs_rq_of(se);
+		cfs_rq->h_load_next = se;
+		if (cfs_rq->last_h_load_update == now)
+			break;
+	}
+
+	if (!se) {
+		cfs_rq->h_load = cfs_rq->runnable_load_avg;
+		cfs_rq->last_h_load_update = now;
+	}
+
+	while ((se = cfs_rq->h_load_next) != NULL) {
+		load = cfs_rq->h_load;
+		load = div64_ul(load * se->avg.load_avg_contrib,
+				cfs_rq->runnable_load_avg + 1);
+		cfs_rq = group_cfs_rq(se);
+		cfs_rq->h_load = load;
+		cfs_rq->last_h_load_update = now;
+	}
+}
+
+static unsigned long task_h_load(struct task_struct *p)
+{
+	struct cfs_rq *cfs_rq = task_cfs_rq(p);
+
+	update_cfs_rq_h_load(cfs_rq);
+	return div64_ul(p->se.avg.load_avg_contrib * cfs_rq->h_load,
+			cfs_rq->runnable_load_avg + 1);
+}
+#else
+static inline void update_blocked_averages(int cpu)
+{
+}
+
+static unsigned long task_h_load(struct task_struct *p)
+{
+	return p->se.avg.load_avg_contrib;
+}
+#endif
+
+/********** Helpers for find_busiest_group ************************/
+
+enum group_type {
+	group_other = 0,
+	group_imbalanced,
+	group_overloaded,
+};
+
+/*
+ * 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_weighted_load; /* Weighted load of group's tasks */
+	unsigned long load_per_task;
+	unsigned long group_capacity;
+	unsigned long group_usage; /* Total usage of the group */
+	unsigned int sum_nr_running; /* Nr tasks running in the group */
+	unsigned int idle_cpus;
+	unsigned int group_weight;
+	enum group_type group_type;
+	int group_no_capacity;
+#ifdef CONFIG_NUMA_BALANCING
+	unsigned int nr_numa_running;
+	unsigned int nr_preferred_running;
+#endif
+};
+
+/*
+ * 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 *local;	/* Local group in this sd */
+	unsigned long total_load;	/* Total load of all groups in sd */
+	unsigned long total_capacity;	/* Total capacity of all groups in sd */
+	unsigned long avg_load;	/* Average load across all groups in sd */
+
+	struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */
+	struct sg_lb_stats local_stat;	/* Statistics of the local group */
+};
+
+static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
+{
+	/*
+	 * Skimp on the clearing to avoid duplicate work. We can avoid clearing
+	 * local_stat because update_sg_lb_stats() does a full clear/assignment.
+	 * We must however clear busiest_stat::avg_load because
+	 * update_sd_pick_busiest() reads this before assignment.
+	 */
+	*sds = (struct sd_lb_stats){
+		.busiest = NULL,
+		.local = NULL,
+		.total_load = 0UL,
+		.total_capacity = 0UL,
+		.busiest_stat = {
+			.avg_load = 0UL,
+			.sum_nr_running = 0,
+			.group_type = group_other,
+		},
+	};
+}
+
+/**
+ * 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_idx is obtained.
+ *
+ * Return: The load index.
+ */
+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;
+}
+
+static unsigned long default_scale_cpu_capacity(struct sched_domain *sd, int cpu)
+{
+	if ((sd->flags & SD_SHARE_CPUCAPACITY) && (sd->span_weight > 1))
+		return sd->smt_gain / sd->span_weight;
+
+	return SCHED_CAPACITY_SCALE;
+}
+
+unsigned long __weak arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)
+{
+	return default_scale_cpu_capacity(sd, cpu);
+}
+
+static unsigned long scale_rt_capacity(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	u64 total, used, age_stamp, avg;
+	s64 delta;
+
+	/*
+	 * 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);
+	delta = __rq_clock_broken(rq) - age_stamp;
+
+	if (unlikely(delta < 0))
+		delta = 0;
+
+	total = sched_avg_period() + delta;
+
+	used = div_u64(avg, total);
+
+	if (likely(used < SCHED_CAPACITY_SCALE))
+		return SCHED_CAPACITY_SCALE - used;
+
+	return 1;
+}
+
+static void update_cpu_capacity(struct sched_domain *sd, int cpu)
+{
+	unsigned long capacity = SCHED_CAPACITY_SCALE;
+	struct sched_group *sdg = sd->groups;
+
+	if (sched_feat(ARCH_CAPACITY))
+		capacity *= arch_scale_cpu_capacity(sd, cpu);
+	else
+		capacity *= default_scale_cpu_capacity(sd, cpu);
+
+	capacity >>= SCHED_CAPACITY_SHIFT;
+
+	cpu_rq(cpu)->cpu_capacity_orig = capacity;
+
+	capacity *= scale_rt_capacity(cpu);
+	capacity >>= SCHED_CAPACITY_SHIFT;
+
+	if (!capacity)
+		capacity = 1;
+
+	cpu_rq(cpu)->cpu_capacity = capacity;
+	sdg->sgc->capacity = capacity;
+}
+
+void update_group_capacity(struct sched_domain *sd, int cpu)
+{
+	struct sched_domain *child = sd->child;
+	struct sched_group *group, *sdg = sd->groups;
+	unsigned long capacity;
+	unsigned long interval;
+
+	interval = msecs_to_jiffies(sd->balance_interval);
+	interval = clamp(interval, 1UL, max_load_balance_interval);
+	sdg->sgc->next_update = jiffies + interval;
+
+	if (!child) {
+		update_cpu_capacity(sd, cpu);
+		return;
+	}
+
+	capacity = 0;
+
+	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)) {
+			struct sched_group_capacity *sgc;
+			struct rq *rq = cpu_rq(cpu);
+
+			/*
+			 * build_sched_domains() -> init_sched_groups_capacity()
+			 * gets here before we've attached the domains to the
+			 * runqueues.
+			 *
+			 * Use capacity_of(), which is set irrespective of domains
+			 * in update_cpu_capacity().
+			 *
+			 * This avoids capacity from being 0 and
+			 * causing divide-by-zero issues on boot.
+			 */
+			if (unlikely(!rq->sd)) {
+				capacity += capacity_of(cpu);
+				continue;
+			}
+
+			sgc = rq->sd->groups->sgc;
+			capacity += sgc->capacity;
+		}
+	} else  {
+		/*
+		 * !SD_OVERLAP domains can assume that child groups
+		 * span the current group.
+		 */ 
+
+		group = child->groups;
+		do {
+			capacity += group->sgc->capacity;
+			group = group->next;
+		} while (group != child->groups);
+	}
+
+	sdg->sgc->capacity = capacity;
+}
+
+/*
+ * Check whether the capacity of the rq has been noticeably reduced by side
+ * activity. The imbalance_pct is used for the threshold.
+ * Return true is the capacity is reduced
+ */
+static inline int
+check_cpu_capacity(struct rq *rq, struct sched_domain *sd)
+{
+	return ((rq->cpu_capacity * sd->imbalance_pct) <
+				(rq->cpu_capacity_orig * 100));
+}
+
+/*
+ * Group imbalance indicates (and tries to solve) the problem where balancing
+ * groups is inadequate due to tsk_cpus_allowed() constraints.
+ *
+ * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a
+ * cpumask covering 1 cpu of the first group and 3 cpus of the second group.
+ * Something like:
+ *
+ * 	{ 0 1 2 3 } { 4 5 6 7 }
+ * 	        *     * * *
+ *
+ * If we were to balance group-wise we'd place two tasks in the first group and
+ * two tasks in the second group. Clearly this is undesired as it will overload
+ * cpu 3 and leave one of the cpus in the second group unused.
+ *
+ * The current solution to this issue is detecting the skew in the first group
+ * by noticing the lower domain failed to reach balance and had difficulty
+ * moving tasks due to affinity constraints.
+ *
+ * When this is so detected; this group becomes a candidate for busiest; see
+ * update_sd_pick_busiest(). And calculate_imbalance() and
+ * find_busiest_group() avoid some of the usual balance conditions to allow it
+ * to create an effective group imbalance.
+ *
+ * This is a somewhat tricky proposition since the next run might not find the
+ * group imbalance and decide the groups need to be balanced again. A most
+ * subtle and fragile situation.
+ */
+
+static inline int sg_imbalanced(struct sched_group *group)
+{
+	return group->sgc->imbalance;
+}
+
+/*
+ * group_has_capacity returns true if the group has spare capacity that could
+ * be used by some tasks.
+ * We consider that a group has spare capacity if the  * number of task is
+ * smaller than the number of CPUs or if the usage is lower than the available
+ * capacity for CFS tasks.
+ * For the latter, we use a threshold to stabilize the state, to take into
+ * account the variance of the tasks' load and to return true if the available
+ * capacity in meaningful for the load balancer.
+ * As an example, an available capacity of 1% can appear but it doesn't make
+ * any benefit for the load balance.
+ */
+static inline bool
+group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs)
+{
+	if (sgs->sum_nr_running < sgs->group_weight)
+		return true;
+
+	if ((sgs->group_capacity * 100) >
+			(sgs->group_usage * env->sd->imbalance_pct))
+		return true;
+
+	return false;
+}
+
+/*
+ *  group_is_overloaded returns true if the group has more tasks than it can
+ *  handle.
+ *  group_is_overloaded is not equals to !group_has_capacity because a group
+ *  with the exact right number of tasks, has no more spare capacity but is not
+ *  overloaded so both group_has_capacity and group_is_overloaded return
+ *  false.
+ */
+static inline bool
+group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs)
+{
+	if (sgs->sum_nr_running <= sgs->group_weight)
+		return false;
+
+	if ((sgs->group_capacity * 100) <
+			(sgs->group_usage * env->sd->imbalance_pct))
+		return true;
+
+	return false;
+}
+
+static enum group_type group_classify(struct lb_env *env,
+		struct sched_group *group,
+		struct sg_lb_stats *sgs)
+{
+	if (sgs->group_no_capacity)
+		return group_overloaded;
+
+	if (sg_imbalanced(group))
+		return group_imbalanced;
+
+	return group_other;
+}
+
+/**
+ * update_sg_lb_stats - Update sched_group's statistics for load balancing.
+ * @env: The load balancing environment.
+ * @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.
+ * @sgs: variable to hold the statistics for this group.
+ * @overload: Indicate more than one runnable task for any CPU.
+ */
+static inline void update_sg_lb_stats(struct lb_env *env,
+			struct sched_group *group, int load_idx,
+			int local_group, struct sg_lb_stats *sgs,
+			bool *overload)
+{
+	unsigned long load;
+	int i;
+
+	memset(sgs, 0, sizeof(*sgs));
+
+	for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
+		struct rq *rq = cpu_rq(i);
+
+		/* Bias balancing toward cpus of our domain */
+		if (local_group)
+			load = target_load(i, load_idx);
+		else
+			load = source_load(i, load_idx);
+
+		sgs->group_load += load;
+		sgs->group_usage += get_cpu_usage(i);
+		sgs->sum_nr_running += rq->cfs.h_nr_running;
+
+		if (rq->nr_running > 1)
+			*overload = true;
+
+#ifdef CONFIG_NUMA_BALANCING
+		sgs->nr_numa_running += rq->nr_numa_running;
+		sgs->nr_preferred_running += rq->nr_preferred_running;
+#endif
+		sgs->sum_weighted_load += weighted_cpuload(i);
+		if (idle_cpu(i))
+			sgs->idle_cpus++;
+	}
+
+	/* Adjust by relative CPU capacity of the group */
+	sgs->group_capacity = group->sgc->capacity;
+	sgs->avg_load = (sgs->group_load*SCHED_CAPACITY_SCALE) / sgs->group_capacity;
+
+	if (sgs->sum_nr_running)
+		sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
+
+	sgs->group_weight = group->group_weight;
+
+	sgs->group_no_capacity = group_is_overloaded(env, sgs);
+	sgs->group_type = group_classify(env, group, sgs);
+}
+
+/**
+ * update_sd_pick_busiest - return 1 on busiest group
+ * @env: The load balancing environment.
+ * @sds: sched_domain statistics
+ * @sg: sched_group candidate to be checked for being the busiest
+ * @sgs: sched_group statistics
+ *
+ * Determine if @sg is a busier group than the previously selected
+ * busiest group.
+ *
+ * Return: %true if @sg is a busier group than the previously selected
+ * busiest group. %false otherwise.
+ */
+static bool update_sd_pick_busiest(struct lb_env *env,
+				   struct sd_lb_stats *sds,
+				   struct sched_group *sg,
+				   struct sg_lb_stats *sgs)
+{
+	struct sg_lb_stats *busiest = &sds->busiest_stat;
+
+	if (sgs->group_type > busiest->group_type)
+		return true;
+
+	if (sgs->group_type < busiest->group_type)
+		return false;
+
+	if (sgs->avg_load <= busiest->avg_load)
+		return false;
+
+	/* This is the busiest node in its class. */
+	if (!(env->sd->flags & SD_ASYM_PACKING))
+		return true;
+
+	/*
+	 * ASYM_PACKING needs to move all the work to the lowest
+	 * numbered CPUs in the group, therefore mark all groups
+	 * higher than ourself as busy.
+	 */
+	if (sgs->sum_nr_running && env->dst_cpu < group_first_cpu(sg)) {
+		if (!sds->busiest)
+			return true;
+
+		if (group_first_cpu(sds->busiest) > group_first_cpu(sg))
+			return true;
+	}
+
+	return false;
+}
+
+#ifdef CONFIG_NUMA_BALANCING
+static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
+{
+	if (sgs->sum_nr_running > sgs->nr_numa_running)
+		return regular;
+	if (sgs->sum_nr_running > sgs->nr_preferred_running)
+		return remote;
+	return all;
+}
+
+static inline enum fbq_type fbq_classify_rq(struct rq *rq)
+{
+	if (rq->nr_running > rq->nr_numa_running)
+		return regular;
+	if (rq->nr_running > rq->nr_preferred_running)
+		return remote;
+	return all;
+}
+#else
+static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
+{
+	return all;
+}
+
+static inline enum fbq_type fbq_classify_rq(struct rq *rq)
+{
+	return regular;
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
+/**
+ * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
+ * @env: The load balancing environment.
+ * @sds: variable to hold the statistics for this sched_domain.
+ */
+static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds)
+{
+	struct sched_domain *child = env->sd->child;
+	struct sched_group *sg = env->sd->groups;
+	struct sg_lb_stats tmp_sgs;
+	int load_idx, prefer_sibling = 0;
+	bool overload = false;
+
+	if (child && child->flags & SD_PREFER_SIBLING)
+		prefer_sibling = 1;
+
+	load_idx = get_sd_load_idx(env->sd, env->idle);
+
+	do {
+		struct sg_lb_stats *sgs = &tmp_sgs;
+		int local_group;
+
+		local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg));
+		if (local_group) {
+			sds->local = sg;
+			sgs = &sds->local_stat;
+
+			if (env->idle != CPU_NEWLY_IDLE ||
+			    time_after_eq(jiffies, sg->sgc->next_update))
+				update_group_capacity(env->sd, env->dst_cpu);
+		}
+
+		update_sg_lb_stats(env, sg, load_idx, local_group, sgs,
+						&overload);
+
+		if (local_group)
+			goto next_group;
+
+		/*
+		 * In case the child domain prefers tasks go to siblings
+		 * first, lower the sg capacity so that we'll try
+		 * and move all the excess tasks away. We lower the capacity
+		 * of a group only if the local group has the capacity to fit
+		 * these excess tasks. The extra check prevents the case where
+		 * you always pull from the heaviest group when it is already
+		 * under-utilized (possible with a large weight task outweighs
+		 * the tasks on the system).
+		 */
+		if (prefer_sibling && sds->local &&
+		    group_has_capacity(env, &sds->local_stat) &&
+		    (sgs->sum_nr_running > 1)) {
+			sgs->group_no_capacity = 1;
+			sgs->group_type = group_overloaded;
+		}
+
+		if (update_sd_pick_busiest(env, sds, sg, sgs)) {
+			sds->busiest = sg;
+			sds->busiest_stat = *sgs;
+		}
+
+next_group:
+		/* Now, start updating sd_lb_stats */
+		sds->total_load += sgs->group_load;
+		sds->total_capacity += sgs->group_capacity;
+
+		sg = sg->next;
+	} while (sg != env->sd->groups);
+
+	if (env->sd->flags & SD_NUMA)
+		env->fbq_type = fbq_classify_group(&sds->busiest_stat);
+
+	if (!env->sd->parent) {
+		/* update overload indicator if we are at root domain */
+		if (env->dst_rq->rd->overload != overload)
+			env->dst_rq->rd->overload = overload;
+	}
+
+}
+
+/**
+ * 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.
+ *
+ * Return: 1 when packing is required and a task should be moved to
+ * this CPU.  The amount of the imbalance is returned in *imbalance.
+ *
+ * @env: The load balancing environment.
+ * @sds: Statistics of the sched_domain which is to be packed
+ */
+static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
+{
+	int busiest_cpu;
+
+	if (!(env->sd->flags & SD_ASYM_PACKING))
+		return 0;
+
+	if (!sds->busiest)
+		return 0;
+
+	busiest_cpu = group_first_cpu(sds->busiest);
+	if (env->dst_cpu > busiest_cpu)
+		return 0;
+
+	env->imbalance = DIV_ROUND_CLOSEST(
+		sds->busiest_stat.avg_load * sds->busiest_stat.group_capacity,
+		SCHED_CAPACITY_SCALE);
+
+	return 1;
+}
+
+/**
+ * fix_small_imbalance - Calculate the minor imbalance that exists
+ *			amongst the groups of a sched_domain, during
+ *			load balancing.
+ * @env: The load balancing environment.
+ * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
+ */
+static inline
+void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
+{
+	unsigned long tmp, capa_now = 0, capa_move = 0;
+	unsigned int imbn = 2;
+	unsigned long scaled_busy_load_per_task;
+	struct sg_lb_stats *local, *busiest;
+
+	local = &sds->local_stat;
+	busiest = &sds->busiest_stat;
+
+	if (!local->sum_nr_running)
+		local->load_per_task = cpu_avg_load_per_task(env->dst_cpu);
+	else if (busiest->load_per_task > local->load_per_task)
+		imbn = 1;
+
+	scaled_busy_load_per_task =
+		(busiest->load_per_task * SCHED_CAPACITY_SCALE) /
+		busiest->group_capacity;
+
+	if (busiest->avg_load + scaled_busy_load_per_task >=
+	    local->avg_load + (scaled_busy_load_per_task * imbn)) {
+		env->imbalance = busiest->load_per_task;
+		return;
+	}
+
+	/*
+	 * OK, we don't have enough imbalance to justify moving tasks,
+	 * however we may be able to increase total CPU capacity used by
+	 * moving them.
+	 */
+
+	capa_now += busiest->group_capacity *
+			min(busiest->load_per_task, busiest->avg_load);
+	capa_now += local->group_capacity *
+			min(local->load_per_task, local->avg_load);
+	capa_now /= SCHED_CAPACITY_SCALE;
+
+	/* Amount of load we'd subtract */
+	if (busiest->avg_load > scaled_busy_load_per_task) {
+		capa_move += busiest->group_capacity *
+			    min(busiest->load_per_task,
+				busiest->avg_load - scaled_busy_load_per_task);
+	}
+
+	/* Amount of load we'd add */
+	if (busiest->avg_load * busiest->group_capacity <
+	    busiest->load_per_task * SCHED_CAPACITY_SCALE) {
+		tmp = (busiest->avg_load * busiest->group_capacity) /
+		      local->group_capacity;
+	} else {
+		tmp = (busiest->load_per_task * SCHED_CAPACITY_SCALE) /
+		      local->group_capacity;
+	}
+	capa_move += local->group_capacity *
+		    min(local->load_per_task, local->avg_load + tmp);
+	capa_move /= SCHED_CAPACITY_SCALE;
+
+	/* Move if we gain throughput */
+	if (capa_move > capa_now)
+		env->imbalance = busiest->load_per_task;
+}
+
+/**
+ * calculate_imbalance - Calculate the amount of imbalance present within the
+ *			 groups of a given sched_domain during load balance.
+ * @env: load balance environment
+ * @sds: statistics of the sched_domain whose imbalance is to be calculated.
+ */
+static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
+{
+	unsigned long max_pull, load_above_capacity = ~0UL;
+	struct sg_lb_stats *local, *busiest;
+
+	local = &sds->local_stat;
+	busiest = &sds->busiest_stat;
+
+	if (busiest->group_type == group_imbalanced) {
+		/*
+		 * In the group_imb case we cannot rely on group-wide averages
+		 * to ensure cpu-load equilibrium, look at wider averages. XXX
+		 */
+		busiest->load_per_task =
+			min(busiest->load_per_task, sds->avg_load);
+	}
+
+	/*
+	 * In the presence of smp nice balancing, certain scenarios can have
+	 * max load less than avg load(as we skip the groups at or below
+	 * its cpu_capacity, while calculating max_load..)
+	 */
+	if (busiest->avg_load <= sds->avg_load ||
+	    local->avg_load >= sds->avg_load) {
+		env->imbalance = 0;
+		return fix_small_imbalance(env, sds);
+	}
+
+	/*
+	 * If there aren't any idle cpus, avoid creating some.
+	 */
+	if (busiest->group_type == group_overloaded &&
+	    local->group_type   == group_overloaded) {
+		load_above_capacity = busiest->sum_nr_running *
+					SCHED_LOAD_SCALE;
+		if (load_above_capacity > busiest->group_capacity)
+			load_above_capacity -= busiest->group_capacity;
+		else
+			load_above_capacity = ~0UL;
+	}
+
+	/*
+	 * 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.
+	 */
+	max_pull = min(busiest->avg_load - sds->avg_load, load_above_capacity);
+
+	/* How much load to actually move to equalise the imbalance */
+	env->imbalance = min(
+		max_pull * busiest->group_capacity,
+		(sds->avg_load - local->avg_load) * local->group_capacity
+	) / SCHED_CAPACITY_SCALE;
+
+	/*
+	 * if *imbalance is less than the average load per runnable task
+	 * there is no guarantee that any tasks will be moved so we'll have
+	 * a think about bumping its value to force at least one task to be
+	 * moved
+	 */
+	if (env->imbalance < busiest->load_per_task)
+		return fix_small_imbalance(env, sds);
+}
+
+/******* 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.
+ *
+ * @env: The load balancing environment.
+ *
+ * Return:	- The busiest group if imbalance exists.
+ *		- If no imbalance and user has opted for power-savings balance,
+ *		   return the least loaded group whose CPUs can be
+ *		   put to idle by rebalancing its tasks onto our group.
+ */
+static struct sched_group *find_busiest_group(struct lb_env *env)
+{
+	struct sg_lb_stats *local, *busiest;
+	struct sd_lb_stats sds;
+
+	init_sd_lb_stats(&sds);
+
+	/*
+	 * Compute the various statistics relavent for load balancing at
+	 * this level.
+	 */
+	update_sd_lb_stats(env, &sds);
+	local = &sds.local_stat;
+	busiest = &sds.busiest_stat;
+
+	/* ASYM feature bypasses nice load balance check */
+	if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) &&
+	    check_asym_packing(env, &sds))
+		return sds.busiest;
+
+	/* There is no busy sibling group to pull tasks from */
+	if (!sds.busiest || busiest->sum_nr_running == 0)
+		goto out_balanced;
+
+	sds.avg_load = (SCHED_CAPACITY_SCALE * sds.total_load)
+						/ sds.total_capacity;
+
+	/*
+	 * If the busiest group is imbalanced the below checks don't
+	 * work because they assume all things are equal, which typically
+	 * isn't true due to cpus_allowed constraints and the like.
+	 */
+	if (busiest->group_type == group_imbalanced)
+		goto force_balance;
+
+	/* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
+	if (env->idle == CPU_NEWLY_IDLE && group_has_capacity(env, local) &&
+	    busiest->group_no_capacity)
+		goto force_balance;
+
+	/*
+	 * If the local group is busier than the selected busiest group
+	 * don't try and pull any tasks.
+	 */
+	if (local->avg_load >= busiest->avg_load)
+		goto out_balanced;
+
+	/*
+	 * Don't pull any tasks if this group is already above the domain
+	 * average load.
+	 */
+	if (local->avg_load >= sds.avg_load)
+		goto out_balanced;
+
+	if (env->idle == CPU_IDLE) {
+		/*
+		 * This cpu is idle. If the busiest group is not overloaded
+		 * and there is no imbalance between this and busiest group
+		 * wrt idle cpus, it is balanced. The imbalance becomes
+		 * significant if the diff is greater than 1 otherwise we
+		 * might end up to just move the imbalance on another group
+		 */
+		if ((busiest->group_type != group_overloaded) &&
+				(local->idle_cpus <= (busiest->idle_cpus + 1)))
+			goto out_balanced;
+	} else {
+		/*
+		 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
+		 * imbalance_pct to be conservative.
+		 */
+		if (100 * busiest->avg_load <=
+				env->sd->imbalance_pct * local->avg_load)
+			goto out_balanced;
+	}
+
+force_balance:
+	/* Looks like there is an imbalance. Compute it */
+	calculate_imbalance(env, &sds);
+	return sds.busiest;
+
+out_balanced:
+	env->imbalance = 0;
+	return NULL;
+}
+
+/*
+ * find_busiest_queue - find the busiest runqueue among the cpus in group.
+ */
+static struct rq *find_busiest_queue(struct lb_env *env,
+				     struct sched_group *group)
+{
+	struct rq *busiest = NULL, *rq;
+	unsigned long busiest_load = 0, busiest_capacity = 1;
+	int i;
+
+	for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
+		unsigned long capacity, wl;
+		enum fbq_type rt;
+
+		rq = cpu_rq(i);
+		rt = fbq_classify_rq(rq);
+
+		/*
+		 * We classify groups/runqueues into three groups:
+		 *  - regular: there are !numa tasks
+		 *  - remote:  there are numa tasks that run on the 'wrong' node
+		 *  - all:     there is no distinction
+		 *
+		 * In order to avoid migrating ideally placed numa tasks,
+		 * ignore those when there's better options.
+		 *
+		 * If we ignore the actual busiest queue to migrate another
+		 * task, the next balance pass can still reduce the busiest
+		 * queue by moving tasks around inside the node.
+		 *
+		 * If we cannot move enough load due to this classification
+		 * the next pass will adjust the group classification and
+		 * allow migration of more tasks.
+		 *
+		 * Both cases only affect the total convergence complexity.
+		 */
+		if (rt > env->fbq_type)
+			continue;
+
+		capacity = capacity_of(i);
+
+		wl = weighted_cpuload(i);
+
+		/*
+		 * When comparing with imbalance, use weighted_cpuload()
+		 * which is not scaled with the cpu capacity.
+		 */
+
+		if (rq->nr_running == 1 && wl > env->imbalance &&
+		    !check_cpu_capacity(rq, env->sd))
+			continue;
+
+		/*
+		 * For the load comparisons with the other cpu's, consider
+		 * the weighted_cpuload() scaled with the cpu capacity, so
+		 * that the load can be moved away from the cpu that is
+		 * potentially running at a lower capacity.
+		 *
+		 * Thus we're looking for max(wl_i / capacity_i), crosswise
+		 * multiplication to rid ourselves of the division works out
+		 * to: wl_i * capacity_j > wl_j * capacity_i;  where j is
+		 * our previous maximum.
+		 */
+		if (wl * busiest_capacity > busiest_load * capacity) {
+			busiest_load = wl;
+			busiest_capacity = capacity;
+			busiest = rq;
+		}
+	}
+
+	return busiest;
+}
+
+/*
+ * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
+ * so long as it is large enough.
+ */
+#define MAX_PINNED_INTERVAL	512
+
+/* Working cpumask for load_balance and load_balance_newidle. */
+DEFINE_PER_CPU(cpumask_var_t, load_balance_mask);
+
+static int need_active_balance(struct lb_env *env)
+{
+	struct sched_domain *sd = env->sd;
+
+	if (env->idle == CPU_NEWLY_IDLE) {
+
+		/*
+		 * ASYM_PACKING needs to force migrate tasks from busy but
+		 * higher numbered CPUs in order to pack all tasks in the
+		 * lowest numbered CPUs.
+		 */
+		if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu)
+			return 1;
+	}
+
+	/*
+	 * The dst_cpu is idle and the src_cpu CPU has only 1 CFS task.
+	 * It's worth migrating the task if the src_cpu's capacity is reduced
+	 * because of other sched_class or IRQs if more capacity stays
+	 * available on dst_cpu.
+	 */
+	if ((env->idle != CPU_NOT_IDLE) &&
+	    (env->src_rq->cfs.h_nr_running == 1)) {
+		if ((check_cpu_capacity(env->src_rq, sd)) &&
+		    (capacity_of(env->src_cpu)*sd->imbalance_pct < capacity_of(env->dst_cpu)*100))
+			return 1;
+	}
+
+	return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
+}
+
+static int active_load_balance_cpu_stop(void *data);
+
+static int should_we_balance(struct lb_env *env)
+{
+	struct sched_group *sg = env->sd->groups;
+	struct cpumask *sg_cpus, *sg_mask;
+	int cpu, balance_cpu = -1;
+
+	/*
+	 * In the newly idle case, we will allow all the cpu's
+	 * to do the newly idle load balance.
+	 */
+	if (env->idle == CPU_NEWLY_IDLE)
+		return 1;
+
+	sg_cpus = sched_group_cpus(sg);
+	sg_mask = sched_group_mask(sg);
+	/* Try to find first idle cpu */
+	for_each_cpu_and(cpu, sg_cpus, env->cpus) {
+		if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu))
+			continue;
+
+		balance_cpu = cpu;
+		break;
+	}
+
+	if (balance_cpu == -1)
+		balance_cpu = group_balance_cpu(sg);
+
+	/*
+	 * First idle cpu or the first cpu(busiest) in this sched group
+	 * is eligible for doing load balancing at this and above domains.
+	 */
+	return balance_cpu == env->dst_cpu;
+}
+
+/*
+ * 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 *continue_balancing)
+{
+	int ld_moved, cur_ld_moved, active_balance = 0;
+	struct sched_domain *sd_parent = sd->parent;
+	struct sched_group *group;
+	struct rq *busiest;
+	unsigned long flags;
+	struct cpumask *cpus = this_cpu_cpumask_var_ptr(load_balance_mask);
+
+	struct lb_env env = {
+		.sd		= sd,
+		.dst_cpu	= this_cpu,
+		.dst_rq		= this_rq,
+		.dst_grpmask    = sched_group_cpus(sd->groups),
+		.idle		= idle,
+		.loop_break	= sched_nr_migrate_break,
+		.cpus		= cpus,
+		.fbq_type	= all,
+		.tasks		= LIST_HEAD_INIT(env.tasks),
+	};
+
+	/*
+	 * For NEWLY_IDLE load_balancing, we don't need to consider
+	 * other cpus in our group
+	 */
+	if (idle == CPU_NEWLY_IDLE)
+		env.dst_grpmask = NULL;
+
+	cpumask_copy(cpus, cpu_active_mask);
+
+	schedstat_inc(sd, lb_count[idle]);
+
+redo:
+	if (!should_we_balance(&env)) {
+		*continue_balancing = 0;
+		goto out_balanced;
+	}
+
+	group = find_busiest_group(&env);
+	if (!group) {
+		schedstat_inc(sd, lb_nobusyg[idle]);
+		goto out_balanced;
+	}
+
+	busiest = find_busiest_queue(&env, group);
+	if (!busiest) {
+		schedstat_inc(sd, lb_nobusyq[idle]);
+		goto out_balanced;
+	}
+
+	BUG_ON(busiest == env.dst_rq);
+
+	schedstat_add(sd, lb_imbalance[idle], env.imbalance);
+
+	env.src_cpu = busiest->cpu;
+	env.src_rq = busiest;
+
+	ld_moved = 0;
+	if (busiest->nr_running > 1) {
+		/*
+		 * Attempt to move tasks. If find_busiest_group has found
+		 * an imbalance but busiest->nr_running <= 1, the group is
+		 * still unbalanced. ld_moved simply stays zero, so it is
+		 * correctly treated as an imbalance.
+		 */
+		env.flags |= LBF_ALL_PINNED;
+		env.loop_max  = min(sysctl_sched_nr_migrate, busiest->nr_running);
+
+more_balance:
+		raw_spin_lock_irqsave(&busiest->lock, flags);
+
+		/*
+		 * cur_ld_moved - load moved in current iteration
+		 * ld_moved     - cumulative load moved across iterations
+		 */
+		cur_ld_moved = detach_tasks(&env);
+
+		/*
+		 * We've detached some tasks from busiest_rq. Every
+		 * task is masked "TASK_ON_RQ_MIGRATING", so we can safely
+		 * unlock busiest->lock, and we are able to be sure
+		 * that nobody can manipulate the tasks in parallel.
+		 * See task_rq_lock() family for the details.
+		 */
+
+		raw_spin_unlock(&busiest->lock);
+
+		if (cur_ld_moved) {
+			attach_tasks(&env);
+			ld_moved += cur_ld_moved;
+		}
+
+		local_irq_restore(flags);
+
+		if (env.flags & LBF_NEED_BREAK) {
+			env.flags &= ~LBF_NEED_BREAK;
+			goto more_balance;
+		}
+
+		/*
+		 * 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_DST_PINNED) && env.imbalance > 0) {
+
+			/* Prevent to re-select dst_cpu via env's cpus */
+			cpumask_clear_cpu(env.dst_cpu, env.cpus);
+
+			env.dst_rq	 = cpu_rq(env.new_dst_cpu);
+			env.dst_cpu	 = env.new_dst_cpu;
+			env.flags	&= ~LBF_DST_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;
+		}
+
+		/*
+		 * We failed to reach balance because of affinity.
+		 */
+		if (sd_parent) {
+			int *group_imbalance = &sd_parent->groups->sgc->imbalance;
+
+			if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0)
+				*group_imbalance = 1;
+		}
+
+		/* All tasks on this runqueue were pinned by CPU affinity */
+		if (unlikely(env.flags & LBF_ALL_PINNED)) {
+			cpumask_clear_cpu(cpu_of(busiest), cpus);
+			if (!cpumask_empty(cpus)) {
+				env.loop = 0;
+				env.loop_break = sched_nr_migrate_break;
+				goto redo;
+			}
+			goto out_all_pinned;
+		}
+	}
+
+	if (!ld_moved) {
+		schedstat_inc(sd, lb_failed[idle]);
+		/*
+		 * Increment the failure counter only on periodic balance.
+		 * We do not want newidle balance, which can be very
+		 * frequent, pollute the failure counter causing
+		 * excessive cache_hot migrations and active balances.
+		 */
+		if (idle != CPU_NEWLY_IDLE)
+			sd->nr_balance_failed++;
+
+		if (need_active_balance(&env)) {
+			raw_spin_lock_irqsave(&busiest->lock, flags);
+
+			/* don't kick the active_load_balance_cpu_stop,
+			 * if the curr task on busiest cpu can't be
+			 * moved to this_cpu
+			 */
+			if (!cpumask_test_cpu(this_cpu,
+					tsk_cpus_allowed(busiest->curr))) {
+				raw_spin_unlock_irqrestore(&busiest->lock,
+							    flags);
+				env.flags |= LBF_ALL_PINNED;
+				goto out_one_pinned;
+			}
+
+			/*
+			 * ->active_balance synchronizes accesses to
+			 * ->active_balance_work.  Once set, it's cleared
+			 * only after active load balance is finished.
+			 */
+			if (!busiest->active_balance) {
+				busiest->active_balance = 1;
+				busiest->push_cpu = this_cpu;
+				active_balance = 1;
+			}
+			raw_spin_unlock_irqrestore(&busiest->lock, flags);
+
+			if (active_balance) {
+				stop_one_cpu_nowait(cpu_of(busiest),
+					active_load_balance_cpu_stop, busiest,
+					&busiest->active_balance_work);
+			}
+
+			/*
+			 * We've kicked active balancing, reset the failure
+			 * counter.
+			 */
+			sd->nr_balance_failed = sd->cache_nice_tries+1;
+		}
+	} else
+		sd->nr_balance_failed = 0;
+
+	if (likely(!active_balance)) {
+		/* We were unbalanced, so reset the balancing interval */
+		sd->balance_interval = sd->min_interval;
+	} else {
+		/*
+		 * If we've begun active balancing, start to back off. This
+		 * case may not be covered by the all_pinned logic if there
+		 * is only 1 task on the busy runqueue (because we don't call
+		 * detach_tasks).
+		 */
+		if (sd->balance_interval < sd->max_interval)
+			sd->balance_interval *= 2;
+	}
+
+	goto out;
+
+out_balanced:
+	/*
+	 * We reach balance although we may have faced some affinity
+	 * constraints. Clear the imbalance flag if it was set.
+	 */
+	if (sd_parent) {
+		int *group_imbalance = &sd_parent->groups->sgc->imbalance;
+
+		if (*group_imbalance)
+			*group_imbalance = 0;
+	}
+
+out_all_pinned:
+	/*
+	 * We reach balance because all tasks are pinned at this level so
+	 * we can't migrate them. Let the imbalance flag set so parent level
+	 * can try to migrate them.
+	 */
+	schedstat_inc(sd, lb_balanced[idle]);
+
+	sd->nr_balance_failed = 0;
+
+out_one_pinned:
+	/* tune up the balancing interval */
+	if (((env.flags & LBF_ALL_PINNED) &&
+			sd->balance_interval < MAX_PINNED_INTERVAL) ||
+			(sd->balance_interval < sd->max_interval))
+		sd->balance_interval *= 2;
+
+	ld_moved = 0;
+out:
+	return ld_moved;
+}
+
+static inline unsigned long
+get_sd_balance_interval(struct sched_domain *sd, int cpu_busy)
+{
+	unsigned long interval = sd->balance_interval;
+
+	if (cpu_busy)
+		interval *= sd->busy_factor;
+
+	/* scale ms to jiffies */
+	interval = msecs_to_jiffies(interval);
+	interval = clamp(interval, 1UL, max_load_balance_interval);
+
+	return interval;
+}
+
+static inline void
+update_next_balance(struct sched_domain *sd, int cpu_busy, unsigned long *next_balance)
+{
+	unsigned long interval, next;
+
+	interval = get_sd_balance_interval(sd, cpu_busy);
+	next = sd->last_balance + interval;
+
+	if (time_after(*next_balance, next))
+		*next_balance = next;
+}
+
+/*
+ * idle_balance is called by schedule() if this_cpu is about to become
+ * idle. Attempts to pull tasks from other CPUs.
+ */
+static int idle_balance(struct rq *this_rq)
+{
+	unsigned long next_balance = jiffies + HZ;
+	int this_cpu = this_rq->cpu;
+	struct sched_domain *sd;
+	int pulled_task = 0;
+	u64 curr_cost = 0;
+
+	idle_enter_fair(this_rq);
+
+	/*
+	 * We must set idle_stamp _before_ calling idle_balance(), such that we
+	 * measure the duration of idle_balance() as idle time.
+	 */
+	this_rq->idle_stamp = rq_clock(this_rq);
+
+	if (this_rq->avg_idle < sysctl_sched_migration_cost ||
+	    !this_rq->rd->overload) {
+		rcu_read_lock();
+		sd = rcu_dereference_check_sched_domain(this_rq->sd);
+		if (sd)
+			update_next_balance(sd, 0, &next_balance);
+		rcu_read_unlock();
+
+		goto out;
+	}
+
+	/*
+	 * Drop the rq->lock, but keep IRQ/preempt disabled.
+	 */
+	raw_spin_unlock(&this_rq->lock);
+
+	update_blocked_averages(this_cpu);
+	rcu_read_lock();
+	for_each_domain(this_cpu, sd) {
+		int continue_balancing = 1;
+		u64 t0, domain_cost;
+
+		if (!(sd->flags & SD_LOAD_BALANCE))
+			continue;
+
+		if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) {
+			update_next_balance(sd, 0, &next_balance);
+			break;
+		}
+
+		if (sd->flags & SD_BALANCE_NEWIDLE) {
+			t0 = sched_clock_cpu(this_cpu);
+
+			pulled_task = load_balance(this_cpu, this_rq,
+						   sd, CPU_NEWLY_IDLE,
+						   &continue_balancing);
+
+			domain_cost = sched_clock_cpu(this_cpu) - t0;
+			if (domain_cost > sd->max_newidle_lb_cost)
+				sd->max_newidle_lb_cost = domain_cost;
+
+			curr_cost += domain_cost;
+		}
+
+		update_next_balance(sd, 0, &next_balance);
+
+		/*
+		 * Stop searching for tasks to pull if there are
+		 * now runnable tasks on this rq.
+		 */
+		if (pulled_task || this_rq->nr_running > 0)
+			break;
+	}
+	rcu_read_unlock();
+
+	raw_spin_lock(&this_rq->lock);
+
+	if (curr_cost > this_rq->max_idle_balance_cost)
+		this_rq->max_idle_balance_cost = curr_cost;
+
+	/*
+	 * While browsing the domains, we released the rq lock, a task could
+	 * have been enqueued in the meantime. Since we're not going idle,
+	 * pretend we pulled a task.
+	 */
+	if (this_rq->cfs.h_nr_running && !pulled_task)
+		pulled_task = 1;
+
+out:
+	/* Move the next balance forward */
+	if (time_after(this_rq->next_balance, next_balance))
+		this_rq->next_balance = next_balance;
+
+	/* Is there a task of a high priority class? */
+	if (this_rq->nr_running != this_rq->cfs.h_nr_running)
+		pulled_task = -1;
+
+	if (pulled_task) {
+		idle_exit_fair(this_rq);
+		this_rq->idle_stamp = 0;
+	}
+
+	return pulled_task;
+}
+
+/*
+ * active_load_balance_cpu_stop is run by cpu stopper. It pushes
+ * running tasks off the busiest CPU onto idle CPUs. It requires at
+ * least 1 task to be running on each physical CPU where possible, and
+ * avoids physical / logical imbalances.
+ */
+static int active_load_balance_cpu_stop(void *data)
+{
+	struct rq *busiest_rq = data;
+	int busiest_cpu = cpu_of(busiest_rq);
+	int target_cpu = busiest_rq->push_cpu;
+	struct rq *target_rq = cpu_rq(target_cpu);
+	struct sched_domain *sd;
+	struct task_struct *p = NULL;
+
+	raw_spin_lock_irq(&busiest_rq->lock);
+
+	/* make sure the requested cpu hasn't gone down in the meantime */
+	if (unlikely(busiest_cpu != smp_processor_id() ||
+		     !busiest_rq->active_balance))
+		goto out_unlock;
+
+	/* Is there any task to move? */
+	if (busiest_rq->nr_running <= 1)
+		goto out_unlock;
+
+	/*
+	 * This condition is "impossible", if it occurs
+	 * we need to fix it. Originally reported by
+	 * Bjorn Helgaas on a 128-cpu setup.
+	 */
+	BUG_ON(busiest_rq == target_rq);
+
+	/* Search for an sd spanning us and the target CPU. */
+	rcu_read_lock();
+	for_each_domain(target_cpu, sd) {
+		if ((sd->flags & SD_LOAD_BALANCE) &&
+		    cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
+				break;
+	}
+
+	if (likely(sd)) {
+		struct lb_env env = {
+			.sd		= sd,
+			.dst_cpu	= target_cpu,
+			.dst_rq		= target_rq,
+			.src_cpu	= busiest_rq->cpu,
+			.src_rq		= busiest_rq,
+			.idle		= CPU_IDLE,
+		};
+
+		schedstat_inc(sd, alb_count);
+
+		p = detach_one_task(&env);
+		if (p)
+			schedstat_inc(sd, alb_pushed);
+		else
+			schedstat_inc(sd, alb_failed);
+	}
+	rcu_read_unlock();
+out_unlock:
+	busiest_rq->active_balance = 0;
+	raw_spin_unlock(&busiest_rq->lock);
+
+	if (p)
+		attach_one_task(target_rq, p);
+
+	local_irq_enable();
+
+	return 0;
+}
+
+static inline int on_null_domain(struct rq *rq)
+{
+	return unlikely(!rcu_dereference_sched(rq->sd));
+}
+
+#ifdef CONFIG_NO_HZ_COMMON
+/*
+ * 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.
+ */
+static struct {
+	cpumask_var_t idle_cpus_mask;
+	atomic_t nr_cpus;
+	unsigned long next_balance;     /* in jiffy units */
+} nohz ____cacheline_aligned;
+
+static inline int find_new_ilb(void)
+{
+	int ilb = cpumask_first(nohz.idle_cpus_mask);
+
+	if (ilb < nr_cpu_ids && idle_cpu(ilb))
+		return ilb;
+
+	return nr_cpu_ids;
+}
+
+/*
+ * 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(void)
+{
+	int ilb_cpu;
+
+	nohz.next_balance++;
+
+	ilb_cpu = find_new_ilb();
+
+	if (ilb_cpu >= nr_cpu_ids)
+		return;
+
+	if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu)))
+		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);
+	return;
+}
+
+static inline void nohz_balance_exit_idle(int cpu)
+{
+	if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
+		/*
+		 * Completely isolated CPUs don't ever set, so we must test.
+		 */
+		if (likely(cpumask_test_cpu(cpu, nohz.idle_cpus_mask))) {
+			cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
+			atomic_dec(&nohz.nr_cpus);
+		}
+		clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
+	}
+}
+
+static inline void set_cpu_sd_state_busy(void)
+{
+	struct sched_domain *sd;
+	int cpu = smp_processor_id();
+
+	rcu_read_lock();
+	sd = rcu_dereference(per_cpu(sd_busy, cpu));
+
+	if (!sd || !sd->nohz_idle)
+		goto unlock;
+	sd->nohz_idle = 0;
+
+	atomic_inc(&sd->groups->sgc->nr_busy_cpus);
+unlock:
+	rcu_read_unlock();
+}
+
+void set_cpu_sd_state_idle(void)
+{
+	struct sched_domain *sd;
+	int cpu = smp_processor_id();
+
+	rcu_read_lock();
+	sd = rcu_dereference(per_cpu(sd_busy, cpu));
+
+	if (!sd || sd->nohz_idle)
+		goto unlock;
+	sd->nohz_idle = 1;
+
+	atomic_dec(&sd->groups->sgc->nr_busy_cpus);
+unlock:
+	rcu_read_unlock();
+}
+
+/*
+ * This routine will record that the cpu is going idle with tick stopped.
+ * This info will be used in performing idle load balancing in the future.
+ */
+void nohz_balance_enter_idle(int cpu)
+{
+	/*
+	 * If this cpu is going down, then nothing needs to be done.
+	 */
+	if (!cpu_active(cpu))
+		return;
+
+	if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
+		return;
+
+	/*
+	 * If we're a completely isolated CPU, we don't play.
+	 */
+	if (on_null_domain(cpu_rq(cpu)))
+		return;
+
+	cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
+	atomic_inc(&nohz.nr_cpus);
+	set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
+}
+
+static int sched_ilb_notifier(struct notifier_block *nfb,
+					unsigned long action, void *hcpu)
+{
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_DYING:
+		nohz_balance_exit_idle(smp_processor_id());
+		return NOTIFY_OK;
+	default:
+		return NOTIFY_DONE;
+	}
+}
+#endif
+
+static DEFINE_SPINLOCK(balancing);
+
+/*
+ * Scale the max load_balance interval with the number of CPUs in the system.
+ * This trades load-balance latency on larger machines for less cross talk.
+ */
+void update_max_interval(void)
+{
+	max_load_balance_interval = HZ*num_online_cpus()/10;
+}
+
+/*
+ * It checks each scheduling domain to see if it is due to be balanced,
+ * and initiates a balancing operation if so.
+ *
+ * Balancing parameters are set up in init_sched_domains.
+ */
+static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle)
+{
+	int continue_balancing = 1;
+	int cpu = rq->cpu;
+	unsigned long interval;
+	struct sched_domain *sd;
+	/* Earliest time when we have to do rebalance again */
+	unsigned long next_balance = jiffies + 60*HZ;
+	int update_next_balance = 0;
+	int need_serialize, need_decay = 0;
+	u64 max_cost = 0;
+
+	update_blocked_averages(cpu);
+
+	rcu_read_lock();
+	for_each_domain(cpu, sd) {
+		/*
+		 * Decay the newidle max times here because this is a regular
+		 * visit to all the domains. Decay ~1% per second.
+		 */
+		if (time_after(jiffies, sd->next_decay_max_lb_cost)) {
+			sd->max_newidle_lb_cost =
+				(sd->max_newidle_lb_cost * 253) / 256;
+			sd->next_decay_max_lb_cost = jiffies + HZ;
+			need_decay = 1;
+		}
+		max_cost += sd->max_newidle_lb_cost;
+
+		if (!(sd->flags & SD_LOAD_BALANCE))
+			continue;
+
+		/*
+		 * Stop the load balance at this level. There is another
+		 * CPU in our sched group which is doing load balancing more
+		 * actively.
+		 */
+		if (!continue_balancing) {
+			if (need_decay)
+				continue;
+			break;
+		}
+
+		interval = get_sd_balance_interval(sd, idle != CPU_IDLE);
+
+		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, &continue_balancing)) {
+				/*
+				 * The LBF_DST_PINNED logic could have changed
+				 * env->dst_cpu, so we can't know our idle
+				 * state even if we migrated tasks. Update it.
+				 */
+				idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE;
+			}
+			sd->last_balance = jiffies;
+			interval = get_sd_balance_interval(sd, idle != CPU_IDLE);
+		}
+		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;
+		}
+	}
+	if (need_decay) {
+		/*
+		 * Ensure the rq-wide value also decays but keep it at a
+		 * reasonable floor to avoid funnies with rq->avg_idle.
+		 */
+		rq->max_idle_balance_cost =
+			max((u64)sysctl_sched_migration_cost, max_cost);
+	}
+	rcu_read_unlock();
+
+	/*
+	 * next_balance will be updated only when there is a need.
+	 * When the cpu is attached to null domain for ex, it will not be
+	 * updated.
+	 */
+	if (likely(update_next_balance))
+		rq->next_balance = next_balance;
+}
+
+#ifdef CONFIG_NO_HZ_COMMON
+/*
+ * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
+ * rebalancing for all the cpus for whom scheduler ticks are stopped.
+ */
+static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
+{
+	int this_cpu = this_rq->cpu;
+	struct rq *rq;
+	int balance_cpu;
+
+	if (idle != CPU_IDLE ||
+	    !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
+		goto end;
+
+	for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
+		if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
+			continue;
+
+		/*
+		 * If this cpu gets work to do, stop the load balancing
+		 * work being done for other cpus. Next load
+		 * balancing owner will pick it up.
+		 */
+		if (need_resched())
+			break;
+
+		rq = cpu_rq(balance_cpu);
+
+		/*
+		 * If time for next balance is due,
+		 * do the balance.
+		 */
+		if (time_after_eq(jiffies, rq->next_balance)) {
+			raw_spin_lock_irq(&rq->lock);
+			update_rq_clock(rq);
+			update_idle_cpu_load(rq);
+			raw_spin_unlock_irq(&rq->lock);
+			rebalance_domains(rq, 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;
+end:
+	clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu));
+}
+
+/*
+ * Current heuristic for kicking the idle load balancer in the presence
+ * of an idle cpu in the system.
+ *   - This rq has more than one task.
+ *   - This rq has at least one CFS task and the capacity of the CPU is
+ *     significantly reduced because of RT tasks or IRQs.
+ *   - At parent of LLC scheduler domain level, this cpu's scheduler group has
+ *     multiple busy cpu.
+ *   - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
+ *     domain span are idle.
+ */
+static inline bool nohz_kick_needed(struct rq *rq)
+{
+	unsigned long now = jiffies;
+	struct sched_domain *sd;
+	struct sched_group_capacity *sgc;
+	int nr_busy, cpu = rq->cpu;
+	bool kick = false;
+
+	if (unlikely(rq->idle_balance))
+		return false;
+
+       /*
+	* 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.
+	*/
+	set_cpu_sd_state_busy();
+	nohz_balance_exit_idle(cpu);
+
+	/*
+	 * None are in tickless mode and hence no need for NOHZ idle load
+	 * balancing.
+	 */
+	if (likely(!atomic_read(&nohz.nr_cpus)))
+		return false;
+
+	if (time_before(now, nohz.next_balance))
+		return false;
+
+	if (rq->nr_running >= 2)
+		return true;
+
+	rcu_read_lock();
+	sd = rcu_dereference(per_cpu(sd_busy, cpu));
+	if (sd) {
+		sgc = sd->groups->sgc;
+		nr_busy = atomic_read(&sgc->nr_busy_cpus);
+
+		if (nr_busy > 1) {
+			kick = true;
+			goto unlock;
+		}
+
+	}
+
+	sd = rcu_dereference(rq->sd);
+	if (sd) {
+		if ((rq->cfs.h_nr_running >= 1) &&
+				check_cpu_capacity(rq, sd)) {
+			kick = true;
+			goto unlock;
+		}
+	}
+
+	sd = rcu_dereference(per_cpu(sd_asym, cpu));
+	if (sd && (cpumask_first_and(nohz.idle_cpus_mask,
+				  sched_domain_span(sd)) < cpu)) {
+		kick = true;
+		goto unlock;
+	}
+
+unlock:
+	rcu_read_unlock();
+	return kick;
+}
+#else
+static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { }
+#endif
+
+/*
+ * run_rebalance_domains is triggered when needed from the scheduler tick.
+ * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
+ */
+static void run_rebalance_domains(struct softirq_action *h)
+{
+	struct rq *this_rq = this_rq();
+	enum cpu_idle_type idle = this_rq->idle_balance ?
+						CPU_IDLE : CPU_NOT_IDLE;
+
+	/*
+	 * If this cpu has a pending nohz_balance_kick, then do the
+	 * balancing on behalf of the other idle cpus whose ticks are
+	 * stopped. Do nohz_idle_balance *before* rebalance_domains to
+	 * give the idle cpus a chance to load balance. Else we may
+	 * load balance only within the local sched_domain hierarchy
+	 * and abort nohz_idle_balance altogether if we pull some load.
+	 */
+	nohz_idle_balance(this_rq, idle);
+	rebalance_domains(this_rq, idle);
+}
+
+/*
+ * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
+ */
+void trigger_load_balance(struct rq *rq)
+{
+	/* Don't need to rebalance while attached to NULL domain */
+	if (unlikely(on_null_domain(rq)))
+		return;
+
+	if (time_after_eq(jiffies, rq->next_balance))
+		raise_softirq(SCHED_SOFTIRQ);
+#ifdef CONFIG_NO_HZ_COMMON
+	if (nohz_kick_needed(rq))
+		nohz_balancer_kick();
+#endif
+}
+
+static void rq_online_fair(struct rq *rq)
+{
+	update_sysctl();
+
+	update_runtime_enabled(rq);
+}
+
+static void rq_offline_fair(struct rq *rq)
+{
+	update_sysctl();
+
+	/* Ensure any throttled groups are reachable by pick_next_task */
+	unthrottle_offline_cfs_rqs(rq);
+}
+
+#endif /* CONFIG_SMP */
+
+/*
+ * scheduler tick hitting a task of our scheduling class:
+ */
+static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
+{
+	struct cfs_rq *cfs_rq;
+	struct sched_entity *se = &curr->se;
+
+	for_each_sched_entity(se) {
+		cfs_rq = cfs_rq_of(se);
+		entity_tick(cfs_rq, se, queued);
+	}
+
+	if (numabalancing_enabled)
+		task_tick_numa(rq, curr);
+
+	update_rq_runnable_avg(rq, 1);
+}
+
+/*
+ * called on fork with the child task as argument from the parent's context
+ *  - child not yet on the tasklist
+ *  - preemption disabled
+ */
+static void task_fork_fair(struct task_struct *p)
+{
+	struct cfs_rq *cfs_rq;
+	struct sched_entity *se = &p->se, *curr;
+	int this_cpu = smp_processor_id();
+	struct rq *rq = this_rq();
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&rq->lock, flags);
+
+	update_rq_clock(rq);
+
+	cfs_rq = task_cfs_rq(current);
+	curr = cfs_rq->curr;
+
+	/*
+	 * Not only the cpu but also the task_group of the parent might have
+	 * been changed after parent->se.parent,cfs_rq were copied to
+	 * child->se.parent,cfs_rq. So call __set_task_cpu() to make those
+	 * of child point to valid ones.
+	 */
+	rcu_read_lock();
+	__set_task_cpu(p, this_cpu);
+	rcu_read_unlock();
+
+	update_curr(cfs_rq);
+
+	if (curr)
+		se->vruntime = curr->vruntime;
+	place_entity(cfs_rq, se, 1);
+
+	if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
+		/*
+		 * Upon rescheduling, sched_class::put_prev_task() will place
+		 * 'current' within the tree based on its new key value.
+		 */
+		swap(curr->vruntime, se->vruntime);
+		resched_curr(rq);
+	}
+
+	se->vruntime -= cfs_rq->min_vruntime;
+
+	raw_spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+/*
+ * Priority of the task has changed. Check to see if we preempt
+ * the current task.
+ */
+static void
+prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
+{
+	if (!task_on_rq_queued(p))
+		return;
+
+	/*
+	 * Reschedule if we are currently running on this runqueue and
+	 * our priority decreased, or if we are not currently running on
+	 * this runqueue and our priority is higher than the current's
+	 */
+	if (rq->curr == p) {
+		if (p->prio > oldprio)
+			resched_curr(rq);
+	} else
+		check_preempt_curr(rq, p, 0);
+}
+
+static void switched_from_fair(struct rq *rq, struct task_struct *p)
+{
+	struct sched_entity *se = &p->se;
+	struct cfs_rq *cfs_rq = cfs_rq_of(se);
+
+	/*
+	 * Ensure the task's vruntime is normalized, so that when it's
+	 * switched back to the fair class the enqueue_entity(.flags=0) will
+	 * do the right thing.
+	 *
+	 * If it's queued, then the dequeue_entity(.flags=0) will already
+	 * have normalized the vruntime, if it's !queued, then only when
+	 * the task is sleeping will it still have non-normalized vruntime.
+	 */
+	if (!task_on_rq_queued(p) && 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;
+	}
+
+#ifdef CONFIG_SMP
+	/*
+	* Remove our load from contribution when we leave sched_fair
+	* and ensure we don't carry in an old decay_count if we
+	* switch back.
+	*/
+	if (se->avg.decay_count) {
+		__synchronize_entity_decay(se);
+		subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib);
+	}
+#endif
+}
+
+/*
+ * We switched to the sched_fair class.
+ */
+static void switched_to_fair(struct rq *rq, struct task_struct *p)
+{
+#ifdef CONFIG_FAIR_GROUP_SCHED
+	struct sched_entity *se = &p->se;
+	/*
+	 * Since the real-depth could have been changed (only FAIR
+	 * class maintain depth value), reset depth properly.
+	 */
+	se->depth = se->parent ? se->parent->depth + 1 : 0;
+#endif
+	if (!task_on_rq_queued(p))
+		return;
+
+	/*
+	 * We were most likely switched from sched_rt, so
+	 * kick off the schedule if running, otherwise just see
+	 * if we can still preempt the current task.
+	 */
+	if (rq->curr == p)
+		resched_curr(rq);
+	else
+		check_preempt_curr(rq, p, 0);
+}
+
+/* Account for a task changing its policy or group.
+ *
+ * This routine is mostly called to set cfs_rq->curr field when a task
+ * migrates between groups/classes.
+ */
+static void set_curr_task_fair(struct rq *rq)
+{
+	struct sched_entity *se = &rq->curr->se;
+
+	for_each_sched_entity(se) {
+		struct cfs_rq *cfs_rq = cfs_rq_of(se);
+
+		set_next_entity(cfs_rq, se);
+		/* ensure bandwidth has been allocated on our new cfs_rq */
+		account_cfs_rq_runtime(cfs_rq, 0);
+	}
+}
+
+void init_cfs_rq(struct cfs_rq *cfs_rq)
+{
+	cfs_rq->tasks_timeline = RB_ROOT;
+	cfs_rq->min_vruntime = (u64)(-(1LL << 20));
+#ifndef CONFIG_64BIT
+	cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
+#endif
+#ifdef CONFIG_SMP
+	atomic64_set(&cfs_rq->decay_counter, 1);
+	atomic_long_set(&cfs_rq->removed_load, 0);
+#endif
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static void task_move_group_fair(struct task_struct *p, int queued)
+{
+	struct sched_entity *se = &p->se;
+	struct cfs_rq *cfs_rq;
+
+	/*
+	 * If the task was not on the rq at the time of this cgroup movement
+	 * it must have been asleep, sleeping tasks keep their ->vruntime
+	 * absolute on their old rq until wakeup (needed for the fair sleeper
+	 * bonus in place_entity()).
+	 *
+	 * If it was on the rq, we've just 'preempted' it, which does convert
+	 * ->vruntime to a relative base.
+	 *
+	 * Make sure both cases convert their relative position when migrating
+	 * to another cgroup's rq. This does somewhat interfere with the
+	 * fair sleeper stuff for the first placement, but who cares.
+	 */
+	/*
+	 * When !queued, 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().
+	 * - Moving a task which has been woken up by try_to_wake_up() and
+	 *   waiting for actually being woken up by sched_ttwu_pending().
+	 *
+	 * To prevent boost or penalty in the new cfs_rq caused by delta
+	 * min_vruntime between the two cfs_rqs, we skip vruntime adjustment.
+	 */
+	if (!queued && (!se->sum_exec_runtime || p->state == TASK_WAKING))
+		queued = 1;
+
+	if (!queued)
+		se->vruntime -= cfs_rq_of(se)->min_vruntime;
+	set_task_rq(p, task_cpu(p));
+	se->depth = se->parent ? se->parent->depth + 1 : 0;
+	if (!queued) {
+		cfs_rq = cfs_rq_of(se);
+		se->vruntime += cfs_rq->min_vruntime;
+#ifdef CONFIG_SMP
+		/*
+		 * migrate_task_rq_fair() will have removed our previous
+		 * contribution, but we must synchronize for ongoing future
+		 * decay.
+		 */
+		se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
+		cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
+#endif
+	}
+}
+
+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;
+	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;
+		se->depth = 0;
+	} else {
+		se->cfs_rq = parent->my_q;
+		se->depth = parent->depth + 1;
+	}
+
+	se->my_q = cfs_rq;
+	/* guarantee group entities always have weight */
+	update_load_set(&se->load, NICE_0_LOAD);
+	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);
+
+		/* Possible calls to update_curr() need rq clock */
+		update_rq_clock(rq);
+		for_each_sched_entity(se)
+			update_cfs_shares(group_cfs_rq(se));
+		raw_spin_unlock_irqrestore(&rq->lock, flags);
+	}
+
+done:
+	mutex_unlock(&shares_mutex);
+	return 0;
+}
+#else /* CONFIG_FAIR_GROUP_SCHED */
+
+void free_fair_sched_group(struct task_group *tg) { }
+
+int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
+{
+	return 1;
+}
+
+void unregister_fair_sched_group(struct task_group *tg, int cpu) { }
+
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
+
+static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
+{
+	struct sched_entity *se = &task->se;
+	unsigned int rr_interval = 0;
+
+	/*
+	 * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
+	 * idle runqueue:
+	 */
+	if (rq->cfs.load.weight)
+		rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se));
+
+	return rr_interval;
+}
+
+/*
+ * All the scheduling class methods:
+ */
+const struct sched_class fair_sched_class = {
+	.next			= &idle_sched_class,
+	.enqueue_task		= enqueue_task_fair,
+	.dequeue_task		= dequeue_task_fair,
+	.yield_task		= yield_task_fair,
+	.yield_to_task		= yield_to_task_fair,
+
+	.check_preempt_curr	= check_preempt_wakeup,
+
+	.pick_next_task		= pick_next_task_fair,
+	.put_prev_task		= put_prev_task_fair,
+
+#ifdef CONFIG_SMP
+	.select_task_rq		= select_task_rq_fair,
+	.migrate_task_rq	= migrate_task_rq_fair,
+
+	.rq_online		= rq_online_fair,
+	.rq_offline		= rq_offline_fair,
+
+	.task_waking		= task_waking_fair,
+#endif
+
+	.set_curr_task          = set_curr_task_fair,
+	.task_tick		= task_tick_fair,
+	.task_fork		= task_fork_fair,
+
+	.prio_changed		= prio_changed_fair,
+	.switched_from		= switched_from_fair,
+	.switched_to		= switched_to_fair,
+
+	.get_rr_interval	= get_rr_interval_fair,
+
+	.update_curr		= update_curr_fair,
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+	.task_move_group	= task_move_group_fair,
+#endif
+};
+
+#ifdef CONFIG_SCHED_DEBUG
+void print_cfs_stats(struct seq_file *m, int cpu)
+{
+	struct cfs_rq *cfs_rq;
+
+	rcu_read_lock();
+	for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
+		print_cfs_rq(m, cpu, cfs_rq);
+	rcu_read_unlock();
+}
+#endif
+
+__init void init_sched_fair_class(void)
+{
+#ifdef CONFIG_SMP
+	open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
+
+#ifdef CONFIG_NO_HZ_COMMON
+	nohz.next_balance = jiffies;
+	zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
+	cpu_notifier(sched_ilb_notifier, 0);
+#endif
+#endif /* SMP */
+
+}