1 files changed, 4346 insertions, 0 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
new file mode 100644
index 00000000000..bc8ee999381
--- /dev/null
+++ b/kernel/sched_fair.c
@@ -0,0 +1,4346 @@
+/*
+ * 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>
+
+/*
+ * Targeted preemption latency for CPU-bound tasks:
+ * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
+ *
+ * NOTE: this latency value is not the same as the concept of
+ * 'timeslice length' - timeslices in CFS are of variable length
+ * and have no persistent notion like in traditional, time-slice
+ * based scheduling concepts.
+ *
+ * (to see the precise effective timeslice length of your workload,
+ *  run vmstat and monitor the context-switches (cs) field)
+ */
+unsigned int sysctl_sched_latency = 6000000ULL;
+unsigned int normalized_sysctl_sched_latency = 6000000ULL;
+
+/*
+ * The initial- and re-scaling of tunables is configurable
+ * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
+ *
+ * Options are:
+ * SCHED_TUNABLESCALING_NONE - unscaled, always *1
+ * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
+ * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
+ */
+enum sched_tunable_scaling sysctl_sched_tunable_scaling
+        = SCHED_TUNABLESCALING_LOG;
+
+/*
+ * Minimal preemption granularity for CPU-bound tasks:
+ * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
+ */
+unsigned int sysctl_sched_min_granularity = 750000ULL;
+unsigned int normalized_sysctl_sched_min_granularity = 750000ULL;
+
+/*
+ * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
+ */
+static unsigned int sched_nr_latency = 8;
+
+/*
+ * After fork, child runs first. If set to 0 (default) then
+ * parent will (try to) run first.
+ */
+unsigned int sysctl_sched_child_runs_first __read_mostly;
+
+/*
+ * SCHED_OTHER wake-up granularity.
+ * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
+ *
+ * This option delays the preemption effects of decoupled workloads
+ * and reduces their over-scheduling. Synchronous workloads will still
+ * have immediate wakeup/sleep latencies.
+ */
+unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
+unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
+
+const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
+
+/*
+ * The exponential sliding  window over which load is averaged for shares
+ * distribution.
+ * (default: 10msec)
+ */
+unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
+
+static const struct sched_class fair_sched_class;
+
+/**************************************************************
+ * CFS operations on generic schedulable entities:
+ */
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+
+/* cpu runqueue to which this cfs_rq is attached */
+static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
+{
+        return cfs_rq->rq;
+}
+
+/* An entity is a task if it doesn't "own" a runqueue */
+#define entity_is_task(se)      (!se->my_q)
+
+static inline struct task_struct *task_of(struct sched_entity *se)
+{
+#ifdef CONFIG_SCHED_DEBUG
+        WARN_ON_ONCE(!entity_is_task(se));
+#endif
+        return container_of(se, struct task_struct, se);
+}
+
+/* Walk up scheduling entities hierarchy */
+#define for_each_sched_entity(se) \
+                for (; se; se = se->parent)
+
+static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
+{
+        return p->se.cfs_rq;
+}
+
+/* runqueue on which this entity is (to be) queued */
+static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
+{
+        return se->cfs_rq;
+}
+
+/* runqueue "owned" by this group */
+static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
+{
+        return grp->my_q;
+}
+
+static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
+{
+        if (!cfs_rq->on_list) {
+                /*
+                 * Ensure we either appear before our parent (if already
+                 * enqueued) or force our parent to appear after us when it is
+                 * enqueued.  The fact that we always enqueue bottom-up
+                 * reduces this to two cases.
+                 */
+                if (cfs_rq->tg->parent &&
+                    cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) {
+                        list_add_rcu(&cfs_rq->leaf_cfs_rq_list,
+                                &rq_of(cfs_rq)->leaf_cfs_rq_list);
+                } else {
+                        list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
+                                &rq_of(cfs_rq)->leaf_cfs_rq_list);
+                }
+
+                cfs_rq->on_list = 1;
+        }
+}
+
+static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
+{
+        if (cfs_rq->on_list) {
+                list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
+                cfs_rq->on_list = 0;
+        }
+}
+
+/* Iterate thr' all leaf cfs_rq's on a runqueue */
+#define for_each_leaf_cfs_rq(rq, cfs_rq) \
+        list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
+
+/* Do the two (enqueued) entities belong to the same group ? */
+static inline int
+is_same_group(struct sched_entity *se, struct sched_entity *pse)
+{
+        if (se->cfs_rq == pse->cfs_rq)
+                return 1;
+
+        return 0;
+}
+
+static inline struct sched_entity *parent_entity(struct sched_entity *se)
+{
+        return se->parent;
+}
+
+/* return depth at which a sched entity is present in the hierarchy */
+static inline int depth_se(struct sched_entity *se)
+{
+        int depth = 0;
+
+        for_each_sched_entity(se)
+                depth++;
+
+        return depth;
+}
+
+static void
+find_matching_se(struct sched_entity **se, struct sched_entity **pse)
+{
+        int se_depth, pse_depth;
+
+        /*
+         * preemption test can be made between sibling entities who are in the
+         * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
+         * both tasks until we find their ancestors who are siblings of common
+         * parent.
+         */
+
+        /* First walk up until both entities are at same depth */
+        se_depth = depth_se(*se);
+        pse_depth = depth_se(*pse);
+
+        while (se_depth > pse_depth) {
+                se_depth--;
+                *se = parent_entity(*se);
+        }
+
+        while (pse_depth > se_depth) {
+                pse_depth--;
+                *pse = parent_entity(*pse);
+        }
+
+        while (!is_same_group(*se, *pse)) {
+                *se = parent_entity(*se);
+                *pse = parent_entity(*pse);
+        }
+}
+
+#else   /* !CONFIG_FAIR_GROUP_SCHED */
+
+static inline struct task_struct *task_of(struct sched_entity *se)
+{
+        return container_of(se, struct task_struct, se);
+}
+
+static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
+{
+        return container_of(cfs_rq, struct rq, cfs);
+}
+
+#define entity_is_task(se)      1
+
+#define for_each_sched_entity(se) \
+                for (; se; se = NULL)
+
+static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
+{
+        return &task_rq(p)->cfs;
+}
+
+static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
+{
+        struct task_struct *p = task_of(se);
+        struct rq *rq = task_rq(p);
+
+        return &rq->cfs;
+}
+
+/* runqueue "owned" by this group */
+static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
+{
+        return NULL;
+}
+
+static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
+{
+}
+
+static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
+{
+}
+
+#define for_each_leaf_cfs_rq(rq, cfs_rq) \
+                for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
+
+static inline int
+is_same_group(struct sched_entity *se, struct sched_entity *pse)
+{
+        return 1;
+}
+
+static inline struct sched_entity *parent_entity(struct sched_entity *se)
+{
+        return NULL;
+}
+
+static inline void
+find_matching_se(struct sched_entity **se, struct sched_entity **pse)
+{
+}
+
+#endif  /* CONFIG_FAIR_GROUP_SCHED */
+
+
+/**************************************************************
+ * Scheduling class tree data structure manipulation methods:
+ */
+
+static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime)
+{
+        s64 delta = (s64)(vruntime - min_vruntime);
+        if (delta > 0)
+                min_vruntime = vruntime;
+
+        return min_vruntime;
+}
+
+static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
+{
+        s64 delta = (s64)(vruntime - min_vruntime);
+        if (delta < 0)
+                min_vruntime = vruntime;
+
+        return min_vruntime;
+}
+
+static inline int entity_before(struct sched_entity *a,
+                                struct sched_entity *b)
+{
+        return (s64)(a->vruntime - b->vruntime) < 0;
+}
+
+static void update_min_vruntime(struct cfs_rq *cfs_rq)
+{
+        u64 vruntime = cfs_rq->min_vruntime;
+
+        if (cfs_rq->curr)
+                vruntime = cfs_rq->curr->vruntime;
+
+        if (cfs_rq->rb_leftmost) {
+                struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost,
+                                                   struct sched_entity,
+                                                   run_node);
+
+                if (!cfs_rq->curr)
+                        vruntime = se->vruntime;
+                else
+                        vruntime = min_vruntime(vruntime, se->vruntime);
+        }
+
+        cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
+#ifndef CONFIG_64BIT
+        smp_wmb();
+        cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
+#endif
+}
+
+/*
+ * Enqueue an entity into the rb-tree:
+ */
+static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
+        struct rb_node *parent = NULL;
+        struct sched_entity *entry;
+        int leftmost = 1;
+
+        /*
+         * Find the right place in the rbtree:
+         */
+        while (*link) {
+                parent = *link;
+                entry = rb_entry(parent, struct sched_entity, run_node);
+                /*
+                 * We dont care about collisions. Nodes with
+                 * the same key stay together.
+                 */
+                if (entity_before(se, entry)) {
+                        link = &parent->rb_left;
+                } else {
+                        link = &parent->rb_right;
+                        leftmost = 0;
+                }
+        }
+
+        /*
+         * Maintain a cache of leftmost tree entries (it is frequently
+         * used):
+         */
+        if (leftmost)
+                cfs_rq->rb_leftmost = &se->run_node;
+
+        rb_link_node(&se->run_node, parent, link);
+        rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
+}
+
+static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        if (cfs_rq->rb_leftmost == &se->run_node) {
+                struct rb_node *next_node;
+
+                next_node = rb_next(&se->run_node);
+                cfs_rq->rb_leftmost = next_node;
+        }
+
+        rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
+}
+
+static 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
+static struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
+{
+        struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
+
+        if (!last)
+                return NULL;
+
+        return rb_entry(last, struct sched_entity, run_node);
+}
+
+/**************************************************************
+ * Scheduling class statistics methods:
+ */
+
+int sched_proc_update_handler(struct ctl_table *table, int write,
+                void __user *buffer, size_t *lenp,
+                loff_t *ppos)
+{
+        int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+        int factor = get_update_sysctl_factor();
+
+        if (ret || !write)
+                return ret;
+
+        sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
+                                        sysctl_sched_min_granularity);
+
+#define WRT_SYSCTL(name) \
+        (normalized_sysctl_##name = sysctl_##name / (factor))
+        WRT_SYSCTL(sched_min_granularity);
+        WRT_SYSCTL(sched_latency);
+        WRT_SYSCTL(sched_wakeup_granularity);
+#undef WRT_SYSCTL
+
+        return 0;
+}
+#endif
+
+/*
+ * delta /= w
+ */
+static inline unsigned long
+calc_delta_fair(unsigned long delta, struct sched_entity *se)
+{
+        if (unlikely(se->load.weight != NICE_0_LOAD))
+                delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load);
+
+        return delta;
+}
+
+/*
+ * The idea is to set a period in which each task runs once.
+ *
+ * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
+ * this period because otherwise the slices get too small.
+ *
+ * p = (nr <= nl) ? l : l*nr/nl
+ */
+static u64 __sched_period(unsigned long nr_running)
+{
+        u64 period = sysctl_sched_latency;
+        unsigned long nr_latency = sched_nr_latency;
+
+        if (unlikely(nr_running > nr_latency)) {
+                period = sysctl_sched_min_granularity;
+                period *= nr_running;
+        }
+
+        return period;
+}
+
+/*
+ * We calculate the wall-time slice from the period by taking a part
+ * proportional to the weight.
+ *
+ * s = p*P[w/rw]
+ */
+static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq);
+
+        for_each_sched_entity(se) {
+                struct load_weight *load;
+                struct load_weight lw;
+
+                cfs_rq = cfs_rq_of(se);
+                load = &cfs_rq->load;
+
+                if (unlikely(!se->on_rq)) {
+                        lw = cfs_rq->load;
+
+                        update_load_add(&lw, se->load.weight);
+                        load = &lw;
+                }
+                slice = calc_delta_mine(slice, se->load.weight, load);
+        }
+        return slice;
+}
+
+/*
+ * We calculate the vruntime slice of a to be inserted task
+ *
+ * vs = s/w
+ */
+static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        return calc_delta_fair(sched_slice(cfs_rq, se), se);
+}
+
+static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update);
+static void update_cfs_shares(struct cfs_rq *cfs_rq);
+
+/*
+ * Update the current task's runtime statistics. Skip current tasks that
+ * are not in our scheduling class.
+ */
+static inline void
+__update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
+              unsigned long delta_exec)
+{
+        unsigned long delta_exec_weighted;
+
+        schedstat_set(curr->statistics.exec_max,
+                      max((u64)delta_exec, curr->statistics.exec_max));
+
+        curr->sum_exec_runtime += delta_exec;
+        schedstat_add(cfs_rq, exec_clock, delta_exec);
+        delta_exec_weighted = calc_delta_fair(delta_exec, curr);
+
+        curr->vruntime += delta_exec_weighted;
+        update_min_vruntime(cfs_rq);
+
+#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
+        cfs_rq->load_unacc_exec_time += delta_exec;
+#endif
+}
+
+static void update_curr(struct cfs_rq *cfs_rq)
+{
+        struct sched_entity *curr = cfs_rq->curr;
+        u64 now = rq_of(cfs_rq)->clock_task;
+        unsigned long delta_exec;
+
+        if (unlikely(!curr))
+                return;
+
+        /*
+         * Get the amount of time the current task was running
+         * since the last time we changed load (this cannot
+         * overflow on 32 bits):
+         */
+        delta_exec = (unsigned long)(now - curr->exec_start);
+        if (!delta_exec)
+                return;
+
+        __update_curr(cfs_rq, curr, delta_exec);
+        curr->exec_start = now;
+
+        if (entity_is_task(curr)) {
+                struct task_struct *curtask = task_of(curr);
+
+                trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
+                cpuacct_charge(curtask, delta_exec);
+                account_group_exec_runtime(curtask, delta_exec);
+        }
+}
+
+static inline void
+update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock);
+}
+
+/*
+ * Task is being enqueued - update stats:
+ */
+static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        /*
+         * Are we enqueueing a waiting task? (for current tasks
+         * a dequeue/enqueue event is a NOP)
+         */
+        if (se != cfs_rq->curr)
+                update_stats_wait_start(cfs_rq, se);
+}
+
+static void
+update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max,
+                        rq_of(cfs_rq)->clock - se->statistics.wait_start));
+        schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1);
+        schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum +
+                        rq_of(cfs_rq)->clock - se->statistics.wait_start);
+#ifdef CONFIG_SCHEDSTATS
+        if (entity_is_task(se)) {
+                trace_sched_stat_wait(task_of(se),
+                        rq_of(cfs_rq)->clock - se->statistics.wait_start);
+        }
+#endif
+        schedstat_set(se->statistics.wait_start, 0);
+}
+
+static inline void
+update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        /*
+         * Mark the end of the wait period if dequeueing a
+         * waiting task:
+         */
+        if (se != cfs_rq->curr)
+                update_stats_wait_end(cfs_rq, se);
+}
+
+/*
+ * We are picking a new current task - update its stats:
+ */
+static inline void
+update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        /*
+         * We are starting a new run period:
+         */
+        se->exec_start = rq_of(cfs_rq)->clock_task;
+}
+
+/**************************************************
+ * Scheduling class queueing methods:
+ */
+
+#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
+static void
+add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
+{
+        cfs_rq->task_weight += weight;
+}
+#else
+static inline void
+add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
+{
+}
+#endif
+
+static void
+account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        update_load_add(&cfs_rq->load, se->load.weight);
+        if (!parent_entity(se))
+                inc_cpu_load(rq_of(cfs_rq), se->load.weight);
+        if (entity_is_task(se)) {
+                add_cfs_task_weight(cfs_rq, se->load.weight);
+                list_add(&se->group_node, &cfs_rq->tasks);
+        }
+        cfs_rq->nr_running++;
+}
+
+static void
+account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        update_load_sub(&cfs_rq->load, se->load.weight);
+        if (!parent_entity(se))
+                dec_cpu_load(rq_of(cfs_rq), se->load.weight);
+        if (entity_is_task(se)) {
+                add_cfs_task_weight(cfs_rq, -se->load.weight);
+                list_del_init(&se->group_node);
+        }
+        cfs_rq->nr_running--;
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+# ifdef CONFIG_SMP
+static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq,
+                                            int global_update)
+{
+        struct task_group *tg = cfs_rq->tg;
+        long load_avg;
+
+        load_avg = div64_u64(cfs_rq->load_avg, cfs_rq->load_period+1);
+        load_avg -= cfs_rq->load_contribution;
+
+        if (global_update || abs(load_avg) > cfs_rq->load_contribution / 8) {
+                atomic_add(load_avg, &tg->load_weight);
+                cfs_rq->load_contribution += load_avg;
+        }
+}
+
+static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
+{
+        u64 period = sysctl_sched_shares_window;
+        u64 now, delta;
+        unsigned long load = cfs_rq->load.weight;
+
+        if (cfs_rq->tg == &root_task_group)
+                return;
+
+        now = rq_of(cfs_rq)->clock_task;
+        delta = now - cfs_rq->load_stamp;
+
+        /* truncate load history at 4 idle periods */
+        if (cfs_rq->load_stamp > cfs_rq->load_last &&
+            now - cfs_rq->load_last > 4 * period) {
+                cfs_rq->load_period = 0;
+                cfs_rq->load_avg = 0;
+                delta = period - 1;
+        }
+
+        cfs_rq->load_stamp = now;
+        cfs_rq->load_unacc_exec_time = 0;
+        cfs_rq->load_period += delta;
+        if (load) {
+                cfs_rq->load_last = now;
+                cfs_rq->load_avg += delta * load;
+        }
+
+        /* consider updating load contribution on each fold or truncate */
+        if (global_update || cfs_rq->load_period > period
+            || !cfs_rq->load_period)
+                update_cfs_rq_load_contribution(cfs_rq, global_update);
+
+        while (cfs_rq->load_period > period) {
+                /*
+                 * Inline assembly required to prevent the compiler
+                 * optimising this loop into a divmod call.
+                 * See __iter_div_u64_rem() for another example of this.
+                 */
+                asm("" : "+rm" (cfs_rq->load_period));
+                cfs_rq->load_period /= 2;
+                cfs_rq->load_avg /= 2;
+        }
+
+        if (!cfs_rq->curr && !cfs_rq->nr_running && !cfs_rq->load_avg)
+                list_del_leaf_cfs_rq(cfs_rq);
+}
+
+static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
+{
+        long load_weight, load, shares;
+
+        load = cfs_rq->load.weight;
+
+        load_weight = atomic_read(&tg->load_weight);
+        load_weight += load;
+        load_weight -= cfs_rq->load_contribution;
+
+        shares = (tg->shares * load);
+        if (load_weight)
+                shares /= load_weight;
+
+        if (shares < MIN_SHARES)
+                shares = MIN_SHARES;
+        if (shares > tg->shares)
+                shares = tg->shares;
+
+        return shares;
+}
+
+static void update_entity_shares_tick(struct cfs_rq *cfs_rq)
+{
+        if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
+                update_cfs_load(cfs_rq, 0);
+                update_cfs_shares(cfs_rq);
+        }
+}
+# else /* CONFIG_SMP */
+static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
+{
+}
+
+static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
+{
+        return tg->shares;
+}
+
+static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
+{
+}
+# endif /* CONFIG_SMP */
+static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
+                            unsigned long weight)
+{
+        if (se->on_rq) {
+                /* commit outstanding execution time */
+                if (cfs_rq->curr == se)
+                        update_curr(cfs_rq);
+                account_entity_dequeue(cfs_rq, se);
+        }
+
+        update_load_set(&se->load, weight);
+
+        if (se->on_rq)
+                account_entity_enqueue(cfs_rq, se);
+}
+
+static void update_cfs_shares(struct cfs_rq *cfs_rq)
+{
+        struct task_group *tg;
+        struct sched_entity *se;
+        long shares;
+
+        tg = cfs_rq->tg;
+        se = tg->se[cpu_of(rq_of(cfs_rq))];
+        if (!se)
+                return;
+#ifndef CONFIG_SMP
+        if (likely(se->load.weight == tg->shares))
+                return;
+#endif
+        shares = calc_cfs_shares(cfs_rq, tg);
+
+        reweight_entity(cfs_rq_of(se), se, shares);
+}
+#else /* CONFIG_FAIR_GROUP_SCHED */
+static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
+{
+}
+
+static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
+{
+}
+
+static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
+{
+}
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
+static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+#ifdef CONFIG_SCHEDSTATS
+        struct task_struct *tsk = NULL;
+
+        if (entity_is_task(se))
+                tsk = task_of(se);
+
+        if (se->statistics.sleep_start) {
+                u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start;
+
+                if ((s64)delta < 0)
+                        delta = 0;
+
+                if (unlikely(delta > se->statistics.sleep_max))
+                        se->statistics.sleep_max = delta;
+
+                se->statistics.sleep_start = 0;
+                se->statistics.sum_sleep_runtime += delta;
+
+                if (tsk) {
+                        account_scheduler_latency(tsk, delta >> 10, 1);
+                        trace_sched_stat_sleep(tsk, delta);
+                }
+        }
+        if (se->statistics.block_start) {
+                u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start;
+
+                if ((s64)delta < 0)
+                        delta = 0;
+
+                if (unlikely(delta > se->statistics.block_max))
+                        se->statistics.block_max = delta;
+
+                se->statistics.block_start = 0;
+                se->statistics.sum_sleep_runtime += delta;
+
+                if (tsk) {
+                        if (tsk->in_iowait) {
+                                se->statistics.iowait_sum += delta;
+                                se->statistics.iowait_count++;
+                                trace_sched_stat_iowait(tsk, delta);
+                        }
+
+                        /*
+                         * Blocking time is in units of nanosecs, so shift by
+                         * 20 to get a milliseconds-range estimation of the
+                         * amount of time that the task spent sleeping:
+                         */
+                        if (unlikely(prof_on == SLEEP_PROFILING)) {
+                                profile_hits(SLEEP_PROFILING,
+                                                (void *)get_wchan(tsk),
+                                                delta >> 20);
+                        }
+                        account_scheduler_latency(tsk, delta >> 10, 0);
+                }
+        }
+#endif
+}
+
+static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+#ifdef CONFIG_SCHED_DEBUG
+        s64 d = se->vruntime - cfs_rq->min_vruntime;
+
+        if (d < 0)
+                d = -d;
+
+        if (d > 3*sysctl_sched_latency)
+                schedstat_inc(cfs_rq, nr_spread_over);
+#endif
+}
+
+static void
+place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
+{
+        u64 vruntime = cfs_rq->min_vruntime;
+
+        /*
+         * The 'current' period is already promised to the current tasks,
+         * however the extra weight of the new task will slow them down a
+         * little, place the new task so that it fits in the slot that
+         * stays open at the end.
+         */
+        if (initial && sched_feat(START_DEBIT))
+                vruntime += sched_vslice(cfs_rq, se);
+
+        /* sleeps up to a single latency don't count. */
+        if (!initial) {
+                unsigned long thresh = sysctl_sched_latency;
+
+                /*
+                 * Halve their sleep time's effect, to allow
+                 * for a gentler effect of sleepers:
+                 */
+                if (sched_feat(GENTLE_FAIR_SLEEPERS))
+                        thresh >>= 1;
+
+                vruntime -= thresh;
+        }
+
+        /* ensure we never gain time by being placed backwards. */
+        vruntime = max_vruntime(se->vruntime, vruntime);
+
+        se->vruntime = vruntime;
+}
+
+static void
+enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
+{
+        /*
+         * Update the normalized vruntime before updating min_vruntime
+         * through callig update_curr().
+         */
+        if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING))
+                se->vruntime += cfs_rq->min_vruntime;
+
+        /*
+         * Update run-time statistics of the 'current'.
+         */
+        update_curr(cfs_rq);
+        update_cfs_load(cfs_rq, 0);
+        account_entity_enqueue(cfs_rq, se);
+        update_cfs_shares(cfs_rq);
+
+        if (flags & ENQUEUE_WAKEUP) {
+                place_entity(cfs_rq, se, 0);
+                enqueue_sleeper(cfs_rq, se);
+        }
+
+        update_stats_enqueue(cfs_rq, se);
+        check_spread(cfs_rq, se);
+        if (se != cfs_rq->curr)
+                __enqueue_entity(cfs_rq, se);
+        se->on_rq = 1;
+
+        if (cfs_rq->nr_running == 1)
+                list_add_leaf_cfs_rq(cfs_rq);
+}
+
+static void __clear_buddies_last(struct sched_entity *se)
+{
+        for_each_sched_entity(se) {
+                struct cfs_rq *cfs_rq = cfs_rq_of(se);
+                if (cfs_rq->last == se)
+                        cfs_rq->last = NULL;
+                else
+                        break;
+        }
+}
+
+static void __clear_buddies_next(struct sched_entity *se)
+{
+        for_each_sched_entity(se) {
+                struct cfs_rq *cfs_rq = cfs_rq_of(se);
+                if (cfs_rq->next == se)
+                        cfs_rq->next = NULL;
+                else
+                        break;
+        }
+}
+
+static void __clear_buddies_skip(struct sched_entity *se)
+{
+        for_each_sched_entity(se) {
+                struct cfs_rq *cfs_rq = cfs_rq_of(se);
+                if (cfs_rq->skip == se)
+                        cfs_rq->skip = NULL;
+                else
+                        break;
+        }
+}
+
+static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        if (cfs_rq->last == se)
+                __clear_buddies_last(se);
+
+        if (cfs_rq->next == se)
+                __clear_buddies_next(se);
+
+        if (cfs_rq->skip == se)
+                __clear_buddies_skip(se);
+}
+
+static void
+dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
+{
+        /*
+         * Update run-time statistics of the 'current'.
+         */
+        update_curr(cfs_rq);
+
+        update_stats_dequeue(cfs_rq, se);
+        if (flags & DEQUEUE_SLEEP) {
+#ifdef CONFIG_SCHEDSTATS
+                if (entity_is_task(se)) {
+                        struct task_struct *tsk = task_of(se);
+
+                        if (tsk->state & TASK_INTERRUPTIBLE)
+                                se->statistics.sleep_start = rq_of(cfs_rq)->clock;
+                        if (tsk->state & TASK_UNINTERRUPTIBLE)
+                                se->statistics.block_start = rq_of(cfs_rq)->clock;
+                }
+#endif
+        }
+
+        clear_buddies(cfs_rq, se);
+
+        if (se != cfs_rq->curr)
+                __dequeue_entity(cfs_rq, se);
+        se->on_rq = 0;
+        update_cfs_load(cfs_rq, 0);
+        account_entity_dequeue(cfs_rq, se);
+
+        /*
+         * Normalize the entity after updating the min_vruntime because the
+         * update can refer to the ->curr item and we need to reflect this
+         * movement in our normalized position.
+         */
+        if (!(flags & DEQUEUE_SLEEP))
+                se->vruntime -= cfs_rq->min_vruntime;
+
+        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;
+
+        ideal_runtime = sched_slice(cfs_rq, curr);
+        delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
+        if (delta_exec > ideal_runtime) {
+                resched_task(rq_of(cfs_rq)->curr);
+                /*
+                 * The current task ran long enough, ensure it doesn't get
+                 * re-elected due to buddy favours.
+                 */
+                clear_buddies(cfs_rq, curr);
+                return;
+        }
+
+        /*
+         * Ensure that a task that missed wakeup preemption by a
+         * narrow margin doesn't have to wait for a full slice.
+         * This also mitigates buddy induced latencies under load.
+         */
+        if (!sched_feat(WAKEUP_PREEMPT))
+                return;
+
+        if (delta_exec < sysctl_sched_min_granularity)
+                return;
+
+        if (cfs_rq->nr_running > 1) {
+                struct sched_entity *se = __pick_first_entity(cfs_rq);
+                s64 delta = curr->vruntime - se->vruntime;
+
+                if (delta < 0)
+                        return;
+
+                if (delta > ideal_runtime)
+                        resched_task(rq_of(cfs_rq)->curr);
+        }
+}
+
+static void
+set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        /* 'current' is not kept within the tree. */
+        if (se->on_rq) {
+                /*
+                 * Any task has to be enqueued before it get to execute on
+                 * a CPU. So account for the time it spent waiting on the
+                 * runqueue.
+                 */
+                update_stats_wait_end(cfs_rq, se);
+                __dequeue_entity(cfs_rq, se);
+        }
+
+        update_stats_curr_start(cfs_rq, se);
+        cfs_rq->curr = se;
+#ifdef CONFIG_SCHEDSTATS
+        /*
+         * Track our maximum slice length, if the CPU's load is at
+         * least twice that of our own weight (i.e. dont track it
+         * when there are only lesser-weight tasks around):
+         */
+        if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
+                se->statistics.slice_max = max(se->statistics.slice_max,
+                        se->sum_exec_runtime - se->prev_sum_exec_runtime);
+        }
+#endif
+        se->prev_sum_exec_runtime = se->sum_exec_runtime;
+}
+
+static int
+wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
+
+/*
+ * Pick the next process, keeping these things in mind, in this order:
+ * 1) keep things fair between processes/task groups
+ * 2) pick the "next" process, since someone really wants that to run
+ * 3) pick the "last" process, for cache locality
+ * 4) do not run the "skip" process, if something else is available
+ */
+static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
+{
+        struct sched_entity *se = __pick_first_entity(cfs_rq);
+        struct sched_entity *left = se;
+
+        /*
+         * Avoid running the skip buddy, if running something else can
+         * be done without getting too unfair.
+         */
+        if (cfs_rq->skip == se) {
+                struct sched_entity *second = __pick_next_entity(se);
+                if (second && wakeup_preempt_entity(second, left) < 1)
+                        se = second;
+        }
+
+        /*
+         * Prefer last buddy, try to return the CPU to a preempted task.
+         */
+        if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
+                se = cfs_rq->last;
+
+        /*
+         * Someone really wants this to run. If it's not unfair, run it.
+         */
+        if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
+                se = cfs_rq->next;
+
+        clear_buddies(cfs_rq, se);
+
+        return se;
+}
+
+static void 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);
+
+        check_spread(cfs_rq, prev);
+        if (prev->on_rq) {
+                update_stats_wait_start(cfs_rq, prev);
+                /* Put 'current' back into the tree. */
+                __enqueue_entity(cfs_rq, prev);
+        }
+        cfs_rq->curr = NULL;
+}
+
+static void
+entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
+{
+        /*
+         * Update run-time statistics of the 'current'.
+         */
+        update_curr(cfs_rq);
+
+        /*
+         * Update share accounting for long-running entities.
+         */
+        update_entity_shares_tick(cfs_rq);
+
+#ifdef CONFIG_SCHED_HRTICK
+        /*
+         * queued ticks are scheduled to match the slice, so don't bother
+         * validating it and just reschedule.
+         */
+        if (queued) {
+                resched_task(rq_of(cfs_rq)->curr);
+                return;
+        }
+        /*
+         * don't let the period tick interfere with the hrtick preemption
+         */
+        if (!sched_feat(DOUBLE_TICK) &&
+                        hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
+                return;
+#endif
+
+        if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
+                check_preempt_tick(cfs_rq, curr);
+}
+
+/**************************************************
+ * CFS operations on tasks:
+ */
+
+#ifdef CONFIG_SCHED_HRTICK
+static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
+{
+        struct sched_entity *se = &p->se;
+        struct cfs_rq *cfs_rq = cfs_rq_of(se);
+
+        WARN_ON(task_rq(p) != rq);
+
+        if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) {
+                u64 slice = sched_slice(cfs_rq, se);
+                u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
+                s64 delta = slice - ran;
+
+                if (delta < 0) {
+                        if (rq->curr == p)
+                                resched_task(p);
+                        return;
+                }
+
+                /*
+                 * Don't schedule slices shorter than 10000ns, that just
+                 * doesn't make sense. Rely on vruntime for fairness.
+                 */
+                if (rq->curr != p)
+                        delta = max_t(s64, 10000LL, delta);
+
+                hrtick_start(rq, delta);
+        }
+}
+
+/*
+ * called from enqueue/dequeue and updates the hrtick when the
+ * current task is from our class and nr_running is low enough
+ * to matter.
+ */
+static void hrtick_update(struct rq *rq)
+{
+        struct task_struct *curr = rq->curr;
+
+        if (curr->sched_class != &fair_sched_class)
+                return;
+
+        if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
+                hrtick_start_fair(rq, curr);
+}
+#else /* !CONFIG_SCHED_HRTICK */
+static inline void
+hrtick_start_fair(struct rq *rq, struct task_struct *p)
+{
+}
+
+static inline void hrtick_update(struct rq *rq)
+{
+}
+#endif
+
+/*
+ * The enqueue_task method is called before nr_running is
+ * increased. Here we update the fair scheduling stats and
+ * then put the task into the rbtree:
+ */
+static void
+enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
+{
+        struct cfs_rq *cfs_rq;
+        struct sched_entity *se = &p->se;
+
+        for_each_sched_entity(se) {
+                if (se->on_rq)
+                        break;
+                cfs_rq = cfs_rq_of(se);
+                enqueue_entity(cfs_rq, se, flags);
+                flags = ENQUEUE_WAKEUP;
+        }
+
+        for_each_sched_entity(se) {
+                cfs_rq = cfs_rq_of(se);
+
+                update_cfs_load(cfs_rq, 0);
+                update_cfs_shares(cfs_rq);
+        }
+
+        hrtick_update(rq);
+}
+
+static void set_next_buddy(struct sched_entity *se);
+
+/*
+ * The dequeue_task method is called before nr_running is
+ * decreased. We remove the task from the rbtree and
+ * update the fair scheduling stats:
+ */
+static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
+{
+        struct cfs_rq *cfs_rq;
+        struct sched_entity *se = &p->se;
+        int task_sleep = flags & DEQUEUE_SLEEP;
+
+        for_each_sched_entity(se) {
+                cfs_rq = cfs_rq_of(se);
+                dequeue_entity(cfs_rq, se, flags);
+
+                /* 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);
+
+                update_cfs_load(cfs_rq, 0);
+                update_cfs_shares(cfs_rq);
+        }
+
+        hrtick_update(rq);
+}
+
+#ifdef CONFIG_SMP
+
+static void task_waking_fair(struct task_struct *p)
+{
+        struct sched_entity *se = &p->se;
+        struct cfs_rq *cfs_rq = cfs_rq_of(se);
+        u64 min_vruntime;
+
+#ifndef CONFIG_64BIT
+        u64 min_vruntime_copy;
+
+        do {
+                min_vruntime_copy = cfs_rq->min_vruntime_copy;
+                smp_rmb();
+                min_vruntime = cfs_rq->min_vruntime;
+        } while (min_vruntime != min_vruntime_copy);
+#else
+        min_vruntime = cfs_rq->min_vruntime;
+#endif
+
+        se->vruntime -= min_vruntime;
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+/*
+ * effective_load() calculates the load change as seen from the root_task_group
+ *
+ * Adding load to a group doesn't make a group heavier, but can cause movement
+ * of group shares between cpus. Assuming the shares were perfectly aligned one
+ * can calculate the shift in shares.
+ */
+static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
+{
+        struct sched_entity *se = tg->se[cpu];
+
+        if (!tg->parent)
+                return wl;
+
+        for_each_sched_entity(se) {
+                long lw, w;
+
+                tg = se->my_q->tg;
+                w = se->my_q->load.weight;
+
+                /* use this cpu's instantaneous contribution */
+                lw = atomic_read(&tg->load_weight);
+                lw -= se->my_q->load_contribution;
+                lw += w + wg;
+
+                wl += w;
+
+                if (lw > 0 && wl < lw)
+                        wl = (wl * tg->shares) / lw;
+                else
+                        wl = tg->shares;
+
+                /* zero point is MIN_SHARES */
+                if (wl < MIN_SHARES)
+                        wl = MIN_SHARES;
+                wl -= se->load.weight;
+                wg = 0;
+        }
+
+        return wl;
+}
+
+#else
+
+static inline unsigned long effective_load(struct task_group *tg, int cpu,
+                unsigned long wl, unsigned long wg)
+{
+        return wl;
+}
+
+#endif
+
+static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
+{
+        s64 this_load, load;
+        int idx, this_cpu, prev_cpu;
+        unsigned long tl_per_task;
+        struct task_group *tg;
+        unsigned long weight;
+        int balanced;
+
+        idx       = sd->wake_idx;
+        this_cpu  = smp_processor_id();
+        prev_cpu  = task_cpu(p);
+        load      = source_load(prev_cpu, idx);
+        this_load = target_load(this_cpu, idx);
+
+        /*
+         * If sync wakeup then subtract the (maximum possible)
+         * effect of the currently running task from the load
+         * of the current CPU:
+         */
+        if (sync) {
+                tg = task_group(current);
+                weight = current->se.load.weight;
+
+                this_load += effective_load(tg, this_cpu, -weight, -weight);
+                load += effective_load(tg, prev_cpu, 0, -weight);
+        }
+
+        tg = task_group(p);
+        weight = p->se.load.weight;
+
+        /*
+         * In low-load situations, where prev_cpu is idle and this_cpu is idle
+         * due to the sync cause above having dropped this_load to 0, we'll
+         * always have an imbalance, but there's really nothing you can do
+         * about that, so that's good too.
+         *
+         * Otherwise check if either cpus are near enough in load to allow this
+         * task to be woken on this_cpu.
+         */
+        if (this_load > 0) {
+                s64 this_eff_load, prev_eff_load;
+
+                this_eff_load = 100;
+                this_eff_load *= power_of(prev_cpu);
+                this_eff_load *= this_load +
+                        effective_load(tg, this_cpu, weight, weight);
+
+                prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2;
+                prev_eff_load *= power_of(this_cpu);
+                prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight);
+
+                balanced = this_eff_load <= prev_eff_load;
+        } else
+                balanced = true;
+
+        /*
+         * If the currently running task will sleep within
+         * a reasonable amount of time then attract this newly
+         * woken task:
+         */
+        if (sync && balanced)
+                return 1;
+
+        schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
+        tl_per_task = cpu_avg_load_per_task(this_cpu);
+
+        if (balanced ||
+            (this_load <= load &&
+             this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
+                /*
+                 * This domain has SD_WAKE_AFFINE and
+                 * p is cache cold in this domain, and
+                 * there is no bad imbalance.
+                 */
+                schedstat_inc(sd, ttwu_move_affine);
+                schedstat_inc(p, se.statistics.nr_wakeups_affine);
+
+                return 1;
+        }
+        return 0;
+}
+
+/*
+ * find_idlest_group finds and returns the least busy CPU group within the
+ * domain.
+ */
+static struct sched_group *
+find_idlest_group(struct sched_domain *sd, struct task_struct *p,
+                  int this_cpu, int load_idx)
+{
+        struct sched_group *idlest = NULL, *group = sd->groups;
+        unsigned long min_load = ULONG_MAX, this_load = 0;
+        int imbalance = 100 + (sd->imbalance_pct-100)/2;
+
+        do {
+                unsigned long load, avg_load;
+                int local_group;
+                int i;
+
+                /* Skip over this group if it has no CPUs allowed */
+                if (!cpumask_intersects(sched_group_cpus(group),
+                                        &p->cpus_allowed))
+                        continue;
+
+                local_group = cpumask_test_cpu(this_cpu,
+                                               sched_group_cpus(group));
+
+                /* Tally up the load of all CPUs in the group */
+                avg_load = 0;
+
+                for_each_cpu(i, sched_group_cpus(group)) {
+                        /* Bias balancing toward cpus of our domain */
+                        if (local_group)
+                                load = source_load(i, load_idx);
+                        else
+                                load = target_load(i, load_idx);
+
+                        avg_load += load;
+                }
+
+                /* Adjust by relative CPU power of the group */
+                avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power;
+
+                if (local_group) {
+                        this_load = avg_load;
+                } else if (avg_load < min_load) {
+                        min_load = avg_load;
+                        idlest = group;
+                }
+        } while (group = group->next, group != sd->groups);
+
+        if (!idlest || 100*this_load < imbalance*min_load)
+                return NULL;
+        return idlest;
+}
+
+/*
+ * find_idlest_cpu - find the idlest cpu among the cpus in group.
+ */
+static int
+find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
+{
+        unsigned long load, min_load = ULONG_MAX;
+        int idlest = -1;
+        int i;
+
+        /* Traverse only the allowed CPUs */
+        for_each_cpu_and(i, sched_group_cpus(group), &p->cpus_allowed) {
+                load = weighted_cpuload(i);
+
+                if (load < min_load || (load == min_load && i == this_cpu)) {
+                        min_load = load;
+                        idlest = i;
+                }
+        }
+
+        return idlest;
+}
+
+/*
+ * Try and locate an idle CPU in the sched_domain.
+ */
+static int select_idle_sibling(struct task_struct *p, int target)
+{
+        int cpu = smp_processor_id();
+        int prev_cpu = task_cpu(p);
+        struct sched_domain *sd;
+        int i;
+
+        /*
+         * If the task is going to be woken-up on this cpu and if it is
+         * already idle, then it is the right target.
+         */
+        if (target == cpu && idle_cpu(cpu))
+                return cpu;
+
+        /*
+         * If the task is going to be woken-up on the cpu where it previously
+         * ran and if it is currently idle, then it the right target.
+         */
+        if (target == prev_cpu && idle_cpu(prev_cpu))
+                return prev_cpu;
+
+        /*
+         * Otherwise, iterate the domains and find an elegible idle cpu.
+         */
+        rcu_read_lock();
+        for_each_domain(target, sd) {
+                if (!(sd->flags & SD_SHARE_PKG_RESOURCES))
+                        break;
+
+                for_each_cpu_and(i, sched_domain_span(sd), &p->cpus_allowed) {
+                        if (idle_cpu(i)) {
+                                target = i;
+                                break;
+                        }
+                }
+
+                /*
+                 * Lets stop looking for an idle sibling when we reached
+                 * the domain that spans the current cpu and prev_cpu.
+                 */
+                if (cpumask_test_cpu(cpu, sched_domain_span(sd)) &&
+                    cpumask_test_cpu(prev_cpu, sched_domain_span(sd)))
+                        break;
+        }
+        rcu_read_unlock();
+
+        return target;
+}
+
+/*
+ * sched_balance_self: balance the current task (running on cpu) in domains
+ * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
+ * SD_BALANCE_EXEC.
+ *
+ * Balance, ie. select the least loaded group.
+ *
+ * Returns the target CPU number, or the same CPU if no balancing is needed.
+ *
+ * preempt must be disabled.
+ */
+static int
+select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
+{
+        struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
+        int cpu = smp_processor_id();
+        int prev_cpu = task_cpu(p);
+        int new_cpu = cpu;
+        int want_affine = 0;
+        int want_sd = 1;
+        int sync = wake_flags & WF_SYNC;
+
+        if (sd_flag & SD_BALANCE_WAKE) {
+                if (cpumask_test_cpu(cpu, &p->cpus_allowed))
+                        want_affine = 1;
+                new_cpu = prev_cpu;
+        }
+
+        rcu_read_lock();
+        for_each_domain(cpu, tmp) {
+                if (!(tmp->flags & SD_LOAD_BALANCE))
+                        continue;
+
+                /*
+                 * If power savings logic is enabled for a domain, see if we
+                 * are not overloaded, if so, don't balance wider.
+                 */
+                if (tmp->flags & (SD_POWERSAVINGS_BALANCE|SD_PREFER_LOCAL)) {
+                        unsigned long power = 0;
+                        unsigned long nr_running = 0;
+                        unsigned long capacity;
+                        int i;
+
+                        for_each_cpu(i, sched_domain_span(tmp)) {
+                                power += power_of(i);
+                                nr_running += cpu_rq(i)->cfs.nr_running;
+                        }
+
+                        capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE);
+
+                        if (tmp->flags & SD_POWERSAVINGS_BALANCE)
+                                nr_running /= 2;
+
+                        if (nr_running < capacity)
+                                want_sd = 0;
+                }
+
+                /*
+                 * If both cpu and prev_cpu are part of this domain,
+                 * cpu is a valid SD_WAKE_AFFINE target.
+                 */
+                if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
+                    cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
+                        affine_sd = tmp;
+                        want_affine = 0;
+                }
+
+                if (!want_sd && !want_affine)
+                        break;
+
+                if (!(tmp->flags & sd_flag))
+                        continue;
+
+                if (want_sd)
+                        sd = tmp;
+        }
+
+        if (affine_sd) {
+                if (cpu == prev_cpu || wake_affine(affine_sd, p, sync))
+                        prev_cpu = cpu;
+
+                new_cpu = select_idle_sibling(p, prev_cpu);
+                goto unlock;
+        }
+
+        while (sd) {
+                int load_idx = sd->forkexec_idx;
+                struct sched_group *group;
+                int weight;
+
+                if (!(sd->flags & sd_flag)) {
+                        sd = sd->child;
+                        continue;
+                }
+
+                if (sd_flag & SD_BALANCE_WAKE)
+                        load_idx = sd->wake_idx;
+
+                group = find_idlest_group(sd, p, cpu, load_idx);
+                if (!group) {
+                        sd = sd->child;
+                        continue;
+                }
+
+                new_cpu = find_idlest_cpu(group, p, cpu);
+                if (new_cpu == -1 || new_cpu == cpu) {
+                        /* Now try balancing at a lower domain level of cpu */
+                        sd = sd->child;
+                        continue;
+                }
+
+                /* Now try balancing at a lower domain level of new_cpu */
+                cpu = new_cpu;
+                weight = sd->span_weight;
+                sd = NULL;
+                for_each_domain(cpu, tmp) {
+                        if (weight <= tmp->span_weight)
+                                break;
+                        if (tmp->flags & sd_flag)
+                                sd = tmp;
+                }
+                /* while loop will break here if sd == NULL */
+        }
+unlock:
+        rcu_read_unlock();
+
+        return new_cpu;
+}
+#endif /* CONFIG_SMP */
+
+static unsigned long
+wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
+{
+        unsigned long gran = sysctl_sched_wakeup_granularity;
+
+        /*
+         * Since its curr running now, convert the gran from real-time
+         * to virtual-time in his units.
+         *
+         * By using 'se' instead of 'curr' we penalize light tasks, so
+         * they get preempted easier. That is, if 'se' < 'curr' then
+         * the resulting gran will be larger, therefore penalizing the
+         * lighter, if otoh 'se' > 'curr' then the resulting gran will
+         * be smaller, again penalizing the lighter task.
+         *
+         * This is especially important for buddies when the leftmost
+         * task is higher priority than the buddy.
+         */
+        return calc_delta_fair(gran, se);
+}
+
+/*
+ * Should 'se' preempt 'curr'.
+ *
+ *             |s1
+ *        |s2
+ *   |s3
+ *         g
+ *      |<--->|c
+ *
+ *  w(c, s1) = -1
+ *  w(c, s2) =  0
+ *  w(c, s3) =  1
+ *
+ */
+static int
+wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
+{
+        s64 gran, vdiff = curr->vruntime - se->vruntime;
+
+        if (vdiff <= 0)
+                return -1;
+
+        gran = wakeup_gran(curr, se);
+        if (vdiff > gran)
+                return 1;
+
+        return 0;
+}
+
+static void set_last_buddy(struct sched_entity *se)
+{
+        if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
+                return;
+
+        for_each_sched_entity(se)
+                cfs_rq_of(se)->last = se;
+}
+
+static void set_next_buddy(struct sched_entity *se)
+{
+        if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
+                return;
+
+        for_each_sched_entity(se)
+                cfs_rq_of(se)->next = se;
+}
+
+static void set_skip_buddy(struct sched_entity *se)
+{
+        for_each_sched_entity(se)
+                cfs_rq_of(se)->skip = se;
+}
+
+/*
+ * Preempt the current task with a newly woken task if needed:
+ */
+static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
+{
+        struct task_struct *curr = rq->curr;
+        struct sched_entity *se = &curr->se, *pse = &p->se;
+        struct cfs_rq *cfs_rq = task_cfs_rq(curr);
+        int scale = cfs_rq->nr_running >= sched_nr_latency;
+        int next_buddy_marked = 0;
+
+        if (unlikely(se == pse))
+                return;
+
+        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.
+         */
+        if (test_tsk_need_resched(curr))
+                return;
+
+        /* Idle tasks are by definition preempted by non-idle tasks. */
+        if (unlikely(curr->policy == SCHED_IDLE) &&
+            likely(p->policy != SCHED_IDLE))
+                goto preempt;
+
+        /*
+         * Batch and idle tasks do not preempt non-idle tasks (their preemption
+         * is driven by the tick):
+         */
+        if (unlikely(p->policy != SCHED_NORMAL))
+                return;
+
+
+        if (!sched_feat(WAKEUP_PREEMPT))
+                return;
+
+        find_matching_se(&se, &pse);
+        update_curr(cfs_rq_of(se));
+        BUG_ON(!pse);
+        if (wakeup_preempt_entity(se, pse) == 1) {
+                /*
+                 * Bias pick_next to pick the sched entity that is
+                 * triggering this preemption.
+                 */
+                if (!next_buddy_marked)
+                        set_next_buddy(pse);
+                goto preempt;
+        }
+
+        return;
+
+preempt:
+        resched_task(curr);
+        /*
+         * Only set the backward buddy when the current task is still
+         * on the rq. This can happen when a wakeup gets interleaved
+         * with schedule on the ->pre_schedule() or idle_balance()
+         * point, either of which can * drop the rq lock.
+         *
+         * Also, during early boot the idle thread is in the fair class,
+         * for obvious reasons its a bad idea to schedule back to it.
+         */
+        if (unlikely(!se->on_rq || curr == rq->idle))
+                return;
+
+        if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
+                set_last_buddy(se);
+}
+
+static struct task_struct *pick_next_task_fair(struct rq *rq)
+{
+        struct task_struct *p;
+        struct cfs_rq *cfs_rq = &rq->cfs;
+        struct sched_entity *se;
+
+        if (!cfs_rq->nr_running)
+                return NULL;
+
+        do {
+                se = pick_next_entity(cfs_rq);
+                set_next_entity(cfs_rq, se);
+                cfs_rq = group_cfs_rq(se);
+        } while (cfs_rq);
+
+        p = task_of(se);
+        hrtick_start_fair(rq, p);
+
+        return p;
+}
+
+/*
+ * Account for a descheduled task:
+ */
+static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
+{
+        struct sched_entity *se = &prev->se;
+        struct cfs_rq *cfs_rq;
+
+        for_each_sched_entity(se) {
+                cfs_rq = cfs_rq_of(se);
+                put_prev_entity(cfs_rq, se);
+        }
+}
+
+/*
+ * sched_yield() is very simple
+ *
+ * The magic of dealing with the ->skip buddy is in pick_next_entity.
+ */
+static void yield_task_fair(struct rq *rq)
+{
+        struct task_struct *curr = rq->curr;
+        struct cfs_rq *cfs_rq = task_cfs_rq(curr);
+        struct sched_entity *se = &curr->se;
+
+        /*
+         * Are we the only task in the tree?
+         */
+        if (unlikely(rq->nr_running == 1))
+                return;
+
+        clear_buddies(cfs_rq, se);
+
+        if (curr->policy != SCHED_BATCH) {
+                update_rq_clock(rq);
+                /*
+                 * Update run-time statistics of the 'current'.
+                 */
+                update_curr(cfs_rq);
+        }
+
+        set_skip_buddy(se);
+}
+
+static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt)
+{
+        struct sched_entity *se = &p->se;
+
+        if (!se->on_rq)
+                return false;
+
+        /* Tell the scheduler that we'd really like pse to run next. */
+        set_next_buddy(se);
+
+        yield_task_fair(rq);
+
+        return true;
+}
+
+#ifdef CONFIG_SMP
+/**************************************************
+ * Fair scheduling class load-balancing methods:
+ */
+
+/*
+ * pull_task - move a task from a remote runqueue to the local runqueue.
+ * Both runqueues must be locked.
+ */
+static void pull_task(struct rq *src_rq, struct task_struct *p,
+                      struct rq *this_rq, int this_cpu)
+{
+        deactivate_task(src_rq, p, 0);
+        set_task_cpu(p, this_cpu);
+        activate_task(this_rq, p, 0);
+        check_preempt_curr(this_rq, p, 0);
+}
+
+/*
+ * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
+ */
+static
+int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
+                     struct sched_domain *sd, enum cpu_idle_type idle,
+                     int *all_pinned)
+{
+        int tsk_cache_hot = 0;
+        /*
+         * We do not migrate tasks that are:
+         * 1) running (obviously), or
+         * 2) cannot be migrated to this CPU due to cpus_allowed, or
+         * 3) are cache-hot on their current CPU.
+         */
+        if (!cpumask_test_cpu(this_cpu, &p->cpus_allowed)) {
+                schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
+                return 0;
+        }
+        *all_pinned = 0;
+
+        if (task_running(rq, p)) {
+                schedstat_inc(p, se.statistics.nr_failed_migrations_running);
+                return 0;
+        }
+
+        /*
+         * Aggressive migration if:
+         * 1) task is cache cold, or
+         * 2) too many balance attempts have failed.
+         */
+
+        tsk_cache_hot = task_hot(p, rq->clock_task, sd);
+        if (!tsk_cache_hot ||
+                sd->nr_balance_failed > sd->cache_nice_tries) {
+#ifdef CONFIG_SCHEDSTATS
+                if (tsk_cache_hot) {
+                        schedstat_inc(sd, lb_hot_gained[idle]);
+                        schedstat_inc(p, se.statistics.nr_forced_migrations);
+                }
+#endif
+                return 1;
+        }
+
+        if (tsk_cache_hot) {
+                schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
+                return 0;
+        }
+        return 1;
+}
+
+/*
+ * move_one_task tries to move exactly one task from busiest to this_rq, as
+ * part of active balancing operations within "domain".
+ * Returns 1 if successful and 0 otherwise.
+ *
+ * Called with both runqueues locked.
+ */
+static int
+move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
+              struct sched_domain *sd, enum cpu_idle_type idle)
+{
+        struct task_struct *p, *n;
+        struct cfs_rq *cfs_rq;
+        int pinned = 0;
+
+        for_each_leaf_cfs_rq(busiest, cfs_rq) {
+                list_for_each_entry_safe(p, n, &cfs_rq->tasks, se.group_node) {
+
+                        if (!can_migrate_task(p, busiest, this_cpu,
+                                                sd, idle, &pinned))
+                                continue;
+
+                        pull_task(busiest, p, this_rq, this_cpu);
+                        /*
+                         * Right now, this is only the second place pull_task()
+                         * is called, so we can safely collect pull_task()
+                         * stats here rather than inside pull_task().
+                         */
+                        schedstat_inc(sd, lb_gained[idle]);
+                        return 1;
+                }
+        }
+
+        return 0;
+}
+
+static unsigned long
+balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
+              unsigned long max_load_move, struct sched_domain *sd,
+              enum cpu_idle_type idle, int *all_pinned,
+              struct cfs_rq *busiest_cfs_rq)
+{
+        int loops = 0, pulled = 0;
+        long rem_load_move = max_load_move;
+        struct task_struct *p, *n;
+
+        if (max_load_move == 0)
+                goto out;
+
+        list_for_each_entry_safe(p, n, &busiest_cfs_rq->tasks, se.group_node) {
+                if (loops++ > sysctl_sched_nr_migrate)
+                        break;
+
+                if ((p->se.load.weight >> 1) > rem_load_move ||
+                    !can_migrate_task(p, busiest, this_cpu, sd, idle,
+                                      all_pinned))
+                        continue;
+
+                pull_task(busiest, p, this_rq, this_cpu);
+                pulled++;
+                rem_load_move -= p->se.load.weight;
+
+#ifdef CONFIG_PREEMPT
+                /*
+                 * NEWIDLE balancing is a source of latency, so preemptible
+                 * kernels will stop after the first task is pulled to minimize
+                 * the critical section.
+                 */
+                if (idle == CPU_NEWLY_IDLE)
+                        break;
+#endif
+
+                /*
+                 * We only want to steal up to the prescribed amount of
+                 * weighted load.
+                 */
+                if (rem_load_move <= 0)
+                        break;
+        }
+out:
+        /*
+         * Right now, this is one of only two places pull_task() is called,
+         * so we can safely collect pull_task() stats here rather than
+         * inside pull_task().
+         */
+        schedstat_add(sd, lb_gained[idle], pulled);
+
+        return max_load_move - rem_load_move;
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+/*
+ * update tg->load_weight by folding this cpu's load_avg
+ */
+static int update_shares_cpu(struct task_group *tg, int cpu)
+{
+        struct cfs_rq *cfs_rq;
+        unsigned long flags;
+        struct rq *rq;
+
+        if (!tg->se[cpu])
+                return 0;
+
+        rq = cpu_rq(cpu);
+        cfs_rq = tg->cfs_rq[cpu];
+
+        raw_spin_lock_irqsave(&rq->lock, flags);
+
+        update_rq_clock(rq);
+        update_cfs_load(cfs_rq, 1);
+
+        /*
+         * We need to update shares after updating tg->load_weight in
+         * order to adjust the weight of groups with long running tasks.
+         */
+        update_cfs_shares(cfs_rq);
+
+        raw_spin_unlock_irqrestore(&rq->lock, flags);
+
+        return 0;
+}
+
+static void update_shares(int cpu)
+{
+        struct cfs_rq *cfs_rq;
+        struct rq *rq = cpu_rq(cpu);
+
+        rcu_read_lock();
+        /*
+         * Iterates the task_group tree in a bottom up fashion, see
+         * list_add_leaf_cfs_rq() for details.
+         */
+        for_each_leaf_cfs_rq(rq, cfs_rq)
+                update_shares_cpu(cfs_rq->tg, cpu);
+        rcu_read_unlock();
+}
+
+/*
+ * Compute the cpu's hierarchical load factor for each task group.
+ * This needs to be done in a top-down fashion because the load of a child
+ * group is a fraction of its parents load.
+ */
+static int tg_load_down(struct task_group *tg, void *data)
+{
+        unsigned long load;
+        long cpu = (long)data;
+
+        if (!tg->parent) {
+                load = cpu_rq(cpu)->load.weight;
+        } else {
+                load = tg->parent->cfs_rq[cpu]->h_load;
+                load *= tg->se[cpu]->load.weight;
+                load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
+        }
+
+        tg->cfs_rq[cpu]->h_load = load;
+
+        return 0;
+}
+
+static void update_h_load(long cpu)
+{
+        walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
+}
+
+static unsigned long
+load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
+                  unsigned long max_load_move,
+                  struct sched_domain *sd, enum cpu_idle_type idle,
+                  int *all_pinned)
+{
+        long rem_load_move = max_load_move;
+        struct cfs_rq *busiest_cfs_rq;
+
+        rcu_read_lock();
+        update_h_load(cpu_of(busiest));
+
+        for_each_leaf_cfs_rq(busiest, busiest_cfs_rq) {
+                unsigned long busiest_h_load = busiest_cfs_rq->h_load;
+                unsigned long busiest_weight = busiest_cfs_rq->load.weight;
+                u64 rem_load, moved_load;
+
+                /*
+                 * empty group
+                 */
+                if (!busiest_cfs_rq->task_weight)
+                        continue;
+
+                rem_load = (u64)rem_load_move * busiest_weight;
+                rem_load = div_u64(rem_load, busiest_h_load + 1);
+
+                moved_load = balance_tasks(this_rq, this_cpu, busiest,
+                                rem_load, sd, idle, all_pinned,
+                                busiest_cfs_rq);
+
+                if (!moved_load)
+                        continue;
+
+                moved_load *= busiest_h_load;
+                moved_load = div_u64(moved_load, busiest_weight + 1);
+
+                rem_load_move -= moved_load;
+                if (rem_load_move < 0)
+                        break;
+        }
+        rcu_read_unlock();
+
+        return max_load_move - rem_load_move;
+}
+#else
+static inline void update_shares(int cpu)
+{
+}
+
+static unsigned long
+load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
+                  unsigned long max_load_move,
+                  struct sched_domain *sd, enum cpu_idle_type idle,
+                  int *all_pinned)
+{
+        return balance_tasks(this_rq, this_cpu, busiest,
+                        max_load_move, sd, idle, all_pinned,
+                        &busiest->cfs);
+}
+#endif
+
+/*
+ * move_tasks tries to move up to max_load_move weighted load from busiest to
+ * this_rq, as part of a balancing operation within domain "sd".
+ * Returns 1 if successful and 0 otherwise.
+ *
+ * Called with both runqueues locked.
+ */
+static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
+                      unsigned long max_load_move,
+                      struct sched_domain *sd, enum cpu_idle_type idle,
+                      int *all_pinned)
+{
+        unsigned long total_load_moved = 0, load_moved;
+
+        do {
+                load_moved = load_balance_fair(this_rq, this_cpu, busiest,
+                                max_load_move - total_load_moved,
+                                sd, idle, all_pinned);
+
+                total_load_moved += load_moved;
+
+#ifdef CONFIG_PREEMPT
+                /*
+                 * NEWIDLE balancing is a source of latency, so preemptible
+                 * kernels will stop after the first task is pulled to minimize
+                 * the critical section.
+                 */
+                if (idle == CPU_NEWLY_IDLE && this_rq->nr_running)
+                        break;
+
+                if (raw_spin_is_contended(&this_rq->lock) ||
+                                raw_spin_is_contended(&busiest->lock))
+                        break;
+#endif
+        } while (load_moved && max_load_move > total_load_moved);
+
+        return total_load_moved > 0;
+}
+
+/********** Helpers for find_busiest_group ************************/
+/*
+ * sd_lb_stats - Structure to store the statistics of a sched_domain
+ *              during load balancing.
+ */
+struct sd_lb_stats {
+        struct sched_group *busiest; /* Busiest group in this sd */
+        struct sched_group *this;  /* Local group in this sd */
+        unsigned long total_load;  /* Total load of all groups in sd */
+        unsigned long total_pwr;   /*   Total power of all groups in sd */
+        unsigned long avg_load;    /* Average load across all groups in sd */
+
+        /** Statistics of this group */
+        unsigned long this_load;
+        unsigned long this_load_per_task;
+        unsigned long this_nr_running;
+        unsigned long this_has_capacity;
+        unsigned int  this_idle_cpus;
+
+        /* Statistics of the busiest group */
+        unsigned int  busiest_idle_cpus;
+        unsigned long max_load;
+        unsigned long busiest_load_per_task;
+        unsigned long busiest_nr_running;
+        unsigned long busiest_group_capacity;
+        unsigned long busiest_has_capacity;
+        unsigned int  busiest_group_weight;
+
+        int group_imb; /* Is there imbalance in this sd */
+#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
+        int power_savings_balance; /* Is powersave balance needed for this sd */
+        struct sched_group *group_min; /* Least loaded group in sd */
+        struct sched_group *group_leader; /* Group which relieves group_min */
+        unsigned long min_load_per_task; /* load_per_task in group_min */
+        unsigned long leader_nr_running; /* Nr running of group_leader */
+        unsigned long min_nr_running; /* Nr running of group_min */
+#endif
+};
+
+/*
+ * sg_lb_stats - stats of a sched_group required for load_balancing
+ */
+struct sg_lb_stats {
+        unsigned long avg_load; /*Avg load across the CPUs of the group */
+        unsigned long group_load; /* Total load over the CPUs of the group */
+        unsigned long sum_nr_running; /* Nr tasks running in the group */
+        unsigned long sum_weighted_load; /* Weighted load of group's tasks */
+        unsigned long group_capacity;
+        unsigned long idle_cpus;
+        unsigned long group_weight;
+        int group_imb; /* Is there an imbalance in the group ? */
+        int group_has_capacity; /* Is there extra capacity in the group? */
+};
+
+/**
+ * group_first_cpu - Returns the first cpu in the cpumask of a sched_group.
+ * @group: The group whose first cpu is to be returned.
+ */
+static inline unsigned int group_first_cpu(struct sched_group *group)
+{
+        return cpumask_first(sched_group_cpus(group));
+}
+
+/**
+ * get_sd_load_idx - Obtain the load index for a given sched domain.
+ * @sd: The sched_domain whose load_idx is to be obtained.
+ * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
+ */
+static inline int get_sd_load_idx(struct sched_domain *sd,
+                                        enum cpu_idle_type idle)
+{
+        int load_idx;
+
+        switch (idle) {
+        case CPU_NOT_IDLE:
+                load_idx = sd->busy_idx;
+                break;
+
+        case CPU_NEWLY_IDLE:
+                load_idx = sd->newidle_idx;
+                break;
+        default:
+                load_idx = sd->idle_idx;
+                break;
+        }
+
+        return load_idx;
+}
+
+
+#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
+/**
+ * init_sd_power_savings_stats - Initialize power savings statistics for
+ * the given sched_domain, during load balancing.
+ *
+ * @sd: Sched domain whose power-savings statistics are to be initialized.
+ * @sds: Variable containing the statistics for sd.
+ * @idle: Idle status of the CPU at which we're performing load-balancing.
+ */
+static inline void init_sd_power_savings_stats(struct sched_domain *sd,
+        struct sd_lb_stats *sds, enum cpu_idle_type idle)
+{
+        /*
+         * Busy processors will not participate in power savings
+         * balance.
+         */
+        if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
+                sds->power_savings_balance = 0;
+        else {
+                sds->power_savings_balance = 1;
+                sds->min_nr_running = ULONG_MAX;
+                sds->leader_nr_running = 0;
+        }
+}
+
+/**
+ * update_sd_power_savings_stats - Update the power saving stats for a
+ * sched_domain while performing load balancing.
+ *
+ * @group: sched_group belonging to the sched_domain under consideration.
+ * @sds: Variable containing the statistics of the sched_domain
+ * @local_group: Does group contain the CPU for which we're performing
+ *              load balancing ?
+ * @sgs: Variable containing the statistics of the group.
+ */
+static inline void update_sd_power_savings_stats(struct sched_group *group,
+        struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
+{
+
+        if (!sds->power_savings_balance)
+                return;
+
+        /*
+         * If the local group is idle or completely loaded
+         * no need to do power savings balance at this domain
+         */
+        if (local_group && (sds->this_nr_running >= sgs->group_capacity ||
+                                !sds->this_nr_running))
+                sds->power_savings_balance = 0;
+
+        /*
+         * If a group is already running at full capacity or idle,
+         * don't include that group in power savings calculations
+         */
+        if (!sds->power_savings_balance ||
+                sgs->sum_nr_running >= sgs->group_capacity ||
+                !sgs->sum_nr_running)
+                return;
+
+        /*
+         * Calculate the group which has the least non-idle load.
+         * This is the group from where we need to pick up the load
+         * for saving power
+         */
+        if ((sgs->sum_nr_running < sds->min_nr_running) ||
+            (sgs->sum_nr_running == sds->min_nr_running &&
+             group_first_cpu(group) > group_first_cpu(sds->group_min))) {
+                sds->group_min = group;
+                sds->min_nr_running = sgs->sum_nr_running;
+                sds->min_load_per_task = sgs->sum_weighted_load /
+                                                sgs->sum_nr_running;
+        }
+
+        /*
+         * Calculate the group which is almost near its
+         * capacity but still has some space to pick up some load
+         * from other group and save more power
+         */
+        if (sgs->sum_nr_running + 1 > sgs->group_capacity)
+                return;
+
+        if (sgs->sum_nr_running > sds->leader_nr_running ||
+            (sgs->sum_nr_running == sds->leader_nr_running &&
+             group_first_cpu(group) < group_first_cpu(sds->group_leader))) {
+                sds->group_leader = group;
+                sds->leader_nr_running = sgs->sum_nr_running;
+        }
+}
+
+/**
+ * check_power_save_busiest_group - see if there is potential for some power-savings balance
+ * @sds: Variable containing the statistics of the sched_domain
+ *      under consideration.
+ * @this_cpu: Cpu at which we're currently performing load-balancing.
+ * @imbalance: Variable to store the imbalance.
+ *
+ * Description:
+ * Check if we have potential to perform some power-savings balance.
+ * If yes, set the busiest group to be the least loaded group in the
+ * sched_domain, so that it's CPUs can be put to idle.
+ *
+ * Returns 1 if there is potential to perform power-savings balance.
+ * Else returns 0.
+ */
+static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
+                                        int this_cpu, unsigned long *imbalance)
+{
+        if (!sds->power_savings_balance)
+                return 0;
+
+        if (sds->this != sds->group_leader ||
+                        sds->group_leader == sds->group_min)
+                return 0;
+
+        *imbalance = sds->min_load_per_task;
+        sds->busiest = sds->group_min;
+
+        return 1;
+
+}
+#else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
+static inline void init_sd_power_savings_stats(struct sched_domain *sd,
+        struct sd_lb_stats *sds, enum cpu_idle_type idle)
+{
+        return;
+}
+
+static inline void update_sd_power_savings_stats(struct sched_group *group,
+        struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
+{
+        return;
+}
+
+static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
+                                        int this_cpu, unsigned long *imbalance)
+{
+        return 0;
+}
+#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
+
+
+unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
+{
+        return SCHED_POWER_SCALE;
+}
+
+unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
+{
+        return default_scale_freq_power(sd, cpu);
+}
+
+unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
+{
+        unsigned long weight = sd->span_weight;
+        unsigned long smt_gain = sd->smt_gain;
+
+        smt_gain /= weight;
+
+        return smt_gain;
+}
+
+unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
+{
+        return default_scale_smt_power(sd, cpu);
+}
+
+unsigned long scale_rt_power(int cpu)
+{
+        struct rq *rq = cpu_rq(cpu);
+        u64 total, available;
+
+        total = sched_avg_period() + (rq->clock - rq->age_stamp);
+
+        if (unlikely(total < rq->rt_avg)) {
+                /* Ensures that power won't end up being negative */
+                available = 0;
+        } else {
+                available = total - rq->rt_avg;
+        }
+
+        if (unlikely((s64)total < SCHED_POWER_SCALE))
+                total = SCHED_POWER_SCALE;
+
+        total >>= SCHED_POWER_SHIFT;
+
+        return div_u64(available, total);
+}
+
+static void update_cpu_power(struct sched_domain *sd, int cpu)
+{
+        unsigned long weight = sd->span_weight;
+        unsigned long power = SCHED_POWER_SCALE;
+        struct sched_group *sdg = sd->groups;
+
+        if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
+                if (sched_feat(ARCH_POWER))
+                        power *= arch_scale_smt_power(sd, cpu);
+                else
+                        power *= default_scale_smt_power(sd, cpu);
+
+                power >>= SCHED_POWER_SHIFT;
+        }
+
+        sdg->sgp->power_orig = power;
+
+        if (sched_feat(ARCH_POWER))
+                power *= arch_scale_freq_power(sd, cpu);
+        else
+                power *= default_scale_freq_power(sd, cpu);
+
+        power >>= SCHED_POWER_SHIFT;
+
+        power *= scale_rt_power(cpu);
+        power >>= SCHED_POWER_SHIFT;
+
+        if (!power)
+                power = 1;
+
+        cpu_rq(cpu)->cpu_power = power;
+        sdg->sgp->power = power;
+}
+
+static void update_group_power(struct sched_domain *sd, int cpu)
+{
+        struct sched_domain *child = sd->child;
+        struct sched_group *group, *sdg = sd->groups;
+        unsigned long power;
+
+        if (!child) {
+                update_cpu_power(sd, cpu);
+                return;
+        }
+
+        power = 0;
+
+        group = child->groups;
+        do {
+                power += group->sgp->power;
+                group = group->next;
+        } while (group != child->groups);
+
+        sdg->sgp->power = power;
+}
+
+/*
+ * Try and fix up capacity for tiny siblings, this is needed when
+ * things like SD_ASYM_PACKING need f_b_g to select another sibling
+ * which on its own isn't powerful enough.
+ *
+ * See update_sd_pick_busiest() and check_asym_packing().
+ */
+static inline int
+fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
+{
+        /*
+         * Only siblings can have significantly less than SCHED_POWER_SCALE
+         */
+        if (!(sd->flags & SD_SHARE_CPUPOWER))
+                return 0;
+
+        /*
+         * If ~90% of the cpu_power is still there, we're good.
+         */
+        if (group->sgp->power * 32 > group->sgp->power_orig * 29)
+                return 1;
+
+        return 0;
+}
+
+/**
+ * update_sg_lb_stats - Update sched_group's statistics for load balancing.
+ * @sd: The sched_domain whose statistics are to be updated.
+ * @group: sched_group whose statistics are to be updated.
+ * @this_cpu: Cpu for which load balance is currently performed.
+ * @idle: Idle status of this_cpu
+ * @load_idx: Load index of sched_domain of this_cpu for load calc.
+ * @local_group: Does group contain this_cpu.
+ * @cpus: Set of cpus considered for load balancing.
+ * @balance: Should we balance.
+ * @sgs: variable to hold the statistics for this group.
+ */
+static inline void update_sg_lb_stats(struct sched_domain *sd,
+                        struct sched_group *group, int this_cpu,
+                        enum cpu_idle_type idle, int load_idx,
+                        int local_group, const struct cpumask *cpus,
+                        int *balance, struct sg_lb_stats *sgs)
+{
+        unsigned long load, max_cpu_load, min_cpu_load, max_nr_running;
+        int i;
+        unsigned int balance_cpu = -1, first_idle_cpu = 0;
+        unsigned long avg_load_per_task = 0;
+
+        if (local_group)
+                balance_cpu = group_first_cpu(group);
+
+        /* Tally up the load of all CPUs in the group */
+        max_cpu_load = 0;
+        min_cpu_load = ~0UL;
+        max_nr_running = 0;
+
+        for_each_cpu_and(i, sched_group_cpus(group), cpus) {
+                struct rq *rq = cpu_rq(i);
+
+                /* Bias balancing toward cpus of our domain */
+                if (local_group) {
+                        if (idle_cpu(i) && !first_idle_cpu) {
+                                first_idle_cpu = 1;
+                                balance_cpu = i;
+                        }
+
+                        load = target_load(i, load_idx);
+                } else {
+                        load = source_load(i, load_idx);
+                        if (load > max_cpu_load) {
+                                max_cpu_load = load;
+                                max_nr_running = rq->nr_running;
+                        }
+                        if (min_cpu_load > load)
+                                min_cpu_load = load;
+                }
+
+                sgs->group_load += load;
+                sgs->sum_nr_running += rq->nr_running;
+                sgs->sum_weighted_load += weighted_cpuload(i);
+                if (idle_cpu(i))
+                        sgs->idle_cpus++;
+        }
+
+        /*
+         * First idle cpu or the first cpu(busiest) in this sched group
+         * is eligible for doing load balancing at this and above
+         * domains. In the newly idle case, we will allow all the cpu's
+         * to do the newly idle load balance.
+         */
+        if (idle != CPU_NEWLY_IDLE && local_group) {
+                if (balance_cpu != this_cpu) {
+                        *balance = 0;
+                        return;
+                }
+                update_group_power(sd, this_cpu);
+        }
+
+        /* Adjust by relative CPU power of the group */
+        sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;
+
+        /*
+         * Consider the group unbalanced when the imbalance is larger
+         * than the average weight of a task.
+         *
+         * APZ: with cgroup the avg task weight can vary wildly and
+         *      might not be a suitable number - should we keep a
+         *      normalized nr_running number somewhere that negates
+         *      the hierarchy?
+         */
+        if (sgs->sum_nr_running)
+                avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
+
+        if ((max_cpu_load - min_cpu_load) >= avg_load_per_task && max_nr_running > 1)
+                sgs->group_imb = 1;
+
+        sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
+                                                SCHED_POWER_SCALE);
+        if (!sgs->group_capacity)
+                sgs->group_capacity = fix_small_capacity(sd, group);
+        sgs->group_weight = group->group_weight;
+
+        if (sgs->group_capacity > sgs->sum_nr_running)
+                sgs->group_has_capacity = 1;
+}
+
+/**
+ * update_sd_pick_busiest - return 1 on busiest group
+ * @sd: sched_domain whose statistics are to be checked
+ * @sds: sched_domain statistics
+ * @sg: sched_group candidate to be checked for being the busiest
+ * @sgs: sched_group statistics
+ * @this_cpu: the current cpu
+ *
+ * Determine if @sg is a busier group than the previously selected
+ * busiest group.
+ */
+static bool update_sd_pick_busiest(struct sched_domain *sd,
+                                   struct sd_lb_stats *sds,
+                                   struct sched_group *sg,
+                                   struct sg_lb_stats *sgs,
+                                   int this_cpu)
+{
+        if (sgs->avg_load <= sds->max_load)
+                return false;
+
+        if (sgs->sum_nr_running > sgs->group_capacity)
+                return true;
+
+        if (sgs->group_imb)
+                return true;
+
+        /*
+         * ASYM_PACKING needs to move all the work to the lowest
+         * numbered CPUs in the group, therefore mark all groups
+         * higher than ourself as busy.
+         */
+        if ((sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running &&
+            this_cpu < group_first_cpu(sg)) {
+                if (!sds->busiest)
+                        return true;
+
+                if (group_first_cpu(sds->busiest) > group_first_cpu(sg))
+                        return true;
+        }
+
+        return false;
+}
+
+/**
+ * update_sd_lb_stats - Update sched_group's statistics for load balancing.
+ * @sd: sched_domain whose statistics are to be updated.
+ * @this_cpu: Cpu for which load balance is currently performed.
+ * @idle: Idle status of this_cpu
+ * @cpus: Set of cpus considered for load balancing.
+ * @balance: Should we balance.
+ * @sds: variable to hold the statistics for this sched_domain.
+ */
+static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
+                        enum cpu_idle_type idle, const struct cpumask *cpus,
+                        int *balance, struct sd_lb_stats *sds)
+{
+        struct sched_domain *child = sd->child;
+        struct sched_group *sg = sd->groups;
+        struct sg_lb_stats sgs;
+        int load_idx, prefer_sibling = 0;
+
+        if (child && child->flags & SD_PREFER_SIBLING)
+                prefer_sibling = 1;
+
+        init_sd_power_savings_stats(sd, sds, idle);
+        load_idx = get_sd_load_idx(sd, idle);
+
+        do {
+                int local_group;
+
+                local_group = cpumask_test_cpu(this_cpu, sched_group_cpus(sg));
+                memset(&sgs, 0, sizeof(sgs));
+                update_sg_lb_stats(sd, sg, this_cpu, idle, load_idx,
+                                local_group, cpus, balance, &sgs);
+
+                if (local_group && !(*balance))
+                        return;
+
+                sds->total_load += sgs.group_load;
+                sds->total_pwr += sg->sgp->power;
+
+                /*
+                 * In case the child domain prefers tasks go to siblings
+                 * first, lower the sg capacity to one so that we'll try
+                 * and move all the excess tasks away. We lower the capacity
+                 * of a group only if the local group has the capacity to fit
+                 * these excess tasks, i.e. nr_running < group_capacity. The
+                 * extra check prevents the case where you always pull from the
+                 * heaviest group when it is already under-utilized (possible
+                 * with a large weight task outweighs the tasks on the system).
+                 */
+                if (prefer_sibling && !local_group && sds->this_has_capacity)
+                        sgs.group_capacity = min(sgs.group_capacity, 1UL);
+
+                if (local_group) {
+                        sds->this_load = sgs.avg_load;
+                        sds->this = sg;
+                        sds->this_nr_running = sgs.sum_nr_running;
+                        sds->this_load_per_task = sgs.sum_weighted_load;
+                        sds->this_has_capacity = sgs.group_has_capacity;
+                        sds->this_idle_cpus = sgs.idle_cpus;
+                } else if (update_sd_pick_busiest(sd, sds, sg, &sgs, this_cpu)) {
+                        sds->max_load = sgs.avg_load;
+                        sds->busiest = sg;
+                        sds->busiest_nr_running = sgs.sum_nr_running;
+                        sds->busiest_idle_cpus = sgs.idle_cpus;
+                        sds->busiest_group_capacity = sgs.group_capacity;
+                        sds->busiest_load_per_task = sgs.sum_weighted_load;
+                        sds->busiest_has_capacity = sgs.group_has_capacity;
+                        sds->busiest_group_weight = sgs.group_weight;
+                        sds->group_imb = sgs.group_imb;
+                }
+
+                update_sd_power_savings_stats(sg, sds, local_group, &sgs);
+                sg = sg->next;
+        } while (sg != sd->groups);
+}
+
+int __weak arch_sd_sibling_asym_packing(void)
+{
+       return 0*SD_ASYM_PACKING;
+}
+
+/**
+ * check_asym_packing - Check to see if the group is packed into the
+ *                      sched doman.
+ *
+ * This is primarily intended to used at the sibling level.  Some
+ * cores like POWER7 prefer to use lower numbered SMT threads.  In the
+ * case of POWER7, it can move to lower SMT modes only when higher
+ * threads are idle.  When in lower SMT modes, the threads will
+ * perform better since they share less core resources.  Hence when we
+ * have idle threads, we want them to be the higher ones.
+ *
+ * This packing function is run on idle threads.  It checks to see if
+ * the busiest CPU in this domain (core in the P7 case) has a higher
+ * CPU number than the packing function is being run on.  Here we are
+ * assuming lower CPU number will be equivalent to lower a SMT thread
+ * number.
+ *
+ * Returns 1 when packing is required and a task should be moved to
+ * this CPU.  The amount of the imbalance is returned in *imbalance.
+ *
+ * @sd: The sched_domain whose packing is to be checked.
+ * @sds: Statistics of the sched_domain which is to be packed
+ * @this_cpu: The cpu at whose sched_domain we're performing load-balance.
+ * @imbalance: returns amount of imbalanced due to packing.
+ */
+static int check_asym_packing(struct sched_domain *sd,
+                              struct sd_lb_stats *sds,
+                              int this_cpu, unsigned long *imbalance)
+{
+        int busiest_cpu;
+
+        if (!(sd->flags & SD_ASYM_PACKING))
+                return 0;
+
+        if (!sds->busiest)
+                return 0;
+
+        busiest_cpu = group_first_cpu(sds->busiest);
+        if (this_cpu > busiest_cpu)
+                return 0;
+
+        *imbalance = DIV_ROUND_CLOSEST(sds->max_load * sds->busiest->sgp->power,
+                                       SCHED_POWER_SCALE);
+        return 1;
+}
+
+/**
+ * fix_small_imbalance - Calculate the minor imbalance that exists
+ *                      amongst the groups of a sched_domain, during
+ *                      load balancing.
+ * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
+ * @this_cpu: The cpu at whose sched_domain we're performing load-balance.
+ * @imbalance: Variable to store the imbalance.
+ */
+static inline void fix_small_imbalance(struct sd_lb_stats *sds,
+                                int this_cpu, unsigned long *imbalance)
+{
+        unsigned long tmp, pwr_now = 0, pwr_move = 0;
+        unsigned int imbn = 2;
+        unsigned long scaled_busy_load_per_task;
+
+        if (sds->this_nr_running) {
+                sds->this_load_per_task /= sds->this_nr_running;
+                if (sds->busiest_load_per_task >
+                                sds->this_load_per_task)
+                        imbn = 1;
+        } else
+                sds->this_load_per_task =
+                        cpu_avg_load_per_task(this_cpu);
+
+        scaled_busy_load_per_task = sds->busiest_load_per_task
+                                         * SCHED_POWER_SCALE;
+        scaled_busy_load_per_task /= sds->busiest->sgp->power;
+
+        if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
+                        (scaled_busy_load_per_task * imbn)) {
+                *imbalance = sds->busiest_load_per_task;
+                return;
+        }
+
+        /*
+         * OK, we don't have enough imbalance to justify moving tasks,
+         * however we may be able to increase total CPU power used by
+         * moving them.
+         */
+
+        pwr_now += sds->busiest->sgp->power *
+                        min(sds->busiest_load_per_task, sds->max_load);
+        pwr_now += sds->this->sgp->power *
+                        min(sds->this_load_per_task, sds->this_load);
+        pwr_now /= SCHED_POWER_SCALE;
+
+        /* Amount of load we'd subtract */
+        tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
+                sds->busiest->sgp->power;
+        if (sds->max_load > tmp)
+                pwr_move += sds->busiest->sgp->power *
+                        min(sds->busiest_load_per_task, sds->max_load - tmp);
+
+        /* Amount of load we'd add */
+        if (sds->max_load * sds->busiest->sgp->power <
+                sds->busiest_load_per_task * SCHED_POWER_SCALE)
+                tmp = (sds->max_load * sds->busiest->sgp->power) /
+                        sds->this->sgp->power;
+        else
+                tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
+                        sds->this->sgp->power;
+        pwr_move += sds->this->sgp->power *
+                        min(sds->this_load_per_task, sds->this_load + tmp);
+        pwr_move /= SCHED_POWER_SCALE;
+
+        /* Move if we gain throughput */
+        if (pwr_move > pwr_now)
+                *imbalance = sds->busiest_load_per_task;
+}
+
+/**
+ * calculate_imbalance - Calculate the amount of imbalance present within the
+ *                       groups of a given sched_domain during load balance.
+ * @sds: statistics of the sched_domain whose imbalance is to be calculated.
+ * @this_cpu: Cpu for which currently load balance is being performed.
+ * @imbalance: The variable to store the imbalance.
+ */
+static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu,
+                unsigned long *imbalance)
+{
+        unsigned long max_pull, load_above_capacity = ~0UL;
+
+        sds->busiest_load_per_task /= sds->busiest_nr_running;
+        if (sds->group_imb) {
+                sds->busiest_load_per_task =
+                        min(sds->busiest_load_per_task, sds->avg_load);
+        }
+
+        /*
+         * In the presence of smp nice balancing, certain scenarios can have
+         * max load less than avg load(as we skip the groups at or below
+         * its cpu_power, while calculating max_load..)
+         */
+        if (sds->max_load < sds->avg_load) {
+                *imbalance = 0;
+                return fix_small_imbalance(sds, this_cpu, imbalance);
+        }
+
+        if (!sds->group_imb) {
+                /*
+                 * Don't want to pull so many tasks that a group would go idle.
+                 */
+                load_above_capacity = (sds->busiest_nr_running -
+                                                sds->busiest_group_capacity);
+
+                load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
+
+                load_above_capacity /= sds->busiest->sgp->power;
+        }
+
+        /*
+         * We're trying to get all the cpus to the average_load, so we don't
+         * want to push ourselves above the average load, nor do we wish to
+         * reduce the max loaded cpu below the average load. At the same time,
+         * we also don't want to reduce the group load below the group capacity
+         * (so that we can implement power-savings policies etc). Thus we look
+         * for the minimum possible imbalance.
+         * Be careful of negative numbers as they'll appear as very large values
+         * with unsigned longs.
+         */
+        max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);
+
+        /* How much load to actually move to equalise the imbalance */
+        *imbalance = min(max_pull * sds->busiest->sgp->power,
+                (sds->avg_load - sds->this_load) * sds->this->sgp->power)
+                        / SCHED_POWER_SCALE;
+
+        /*
+         * if *imbalance is less than the average load per runnable task
+         * there is no guarantee that any tasks will be moved so we'll have
+         * a think about bumping its value to force at least one task to be
+         * moved
+         */
+        if (*imbalance < sds->busiest_load_per_task)
+                return fix_small_imbalance(sds, this_cpu, imbalance);
+
+}
+
+/******* find_busiest_group() helpers end here *********************/
+
+/**
+ * find_busiest_group - Returns the busiest group within the sched_domain
+ * if there is an imbalance. If there isn't an imbalance, and
+ * the user has opted for power-savings, it returns a group whose
+ * CPUs can be put to idle by rebalancing those tasks elsewhere, if
+ * such a group exists.
+ *
+ * Also calculates the amount of weighted load which should be moved
+ * to restore balance.
+ *
+ * @sd: The sched_domain whose busiest group is to be returned.
+ * @this_cpu: The cpu for which load balancing is currently being performed.
+ * @imbalance: Variable which stores amount of weighted load which should
+ *              be moved to restore balance/put a group to idle.
+ * @idle: The idle status of this_cpu.
+ * @cpus: The set of CPUs under consideration for load-balancing.
+ * @balance: Pointer to a variable indicating if this_cpu
+ *      is the appropriate cpu to perform load balancing at this_level.
+ *
+ * Returns:     - the busiest group if imbalance exists.
+ *              - If no imbalance and user has opted for power-savings balance,
+ *                 return the least loaded group whose CPUs can be
+ *                 put to idle by rebalancing its tasks onto our group.
+ */
+static struct sched_group *
+find_busiest_group(struct sched_domain *sd, int this_cpu,
+                   unsigned long *imbalance, enum cpu_idle_type idle,
+                   const struct cpumask *cpus, int *balance)
+{
+        struct sd_lb_stats sds;
+
+        memset(&sds, 0, sizeof(sds));
+
+        /*
+         * Compute the various statistics relavent for load balancing at
+         * this level.
+         */
+        update_sd_lb_stats(sd, this_cpu, idle, cpus, balance, &sds);
+
+        /*
+         * this_cpu is not the appropriate cpu to perform load balancing at
+         * this level.
+         */
+        if (!(*balance))
+                goto ret;
+
+        if ((idle == CPU_IDLE || idle == CPU_NEWLY_IDLE) &&
+            check_asym_packing(sd, &sds, this_cpu, imbalance))
+                return sds.busiest;
+
+        /* There is no busy sibling group to pull tasks from */
+        if (!sds.busiest || sds.busiest_nr_running == 0)
+                goto out_balanced;
+
+        sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
+
+        /*
+         * If the busiest group is imbalanced the below checks don't
+         * work because they assumes all things are equal, which typically
+         * isn't true due to cpus_allowed constraints and the like.
+         */
+        if (sds.group_imb)
+                goto force_balance;
+
+        /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
+        if (idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
+                        !sds.busiest_has_capacity)
+                goto force_balance;
+
+        /*
+         * If the local group is more busy than the selected busiest group
+         * don't try and pull any tasks.
+         */
+        if (sds.this_load >= sds.max_load)
+                goto out_balanced;
+
+        /*
+         * Don't pull any tasks if this group is already above the domain
+         * average load.
+         */
+        if (sds.this_load >= sds.avg_load)
+                goto out_balanced;
+
+        if (idle == CPU_IDLE) {
+                /*
+                 * This cpu is idle. If the busiest group load doesn't
+                 * have more tasks than the number of available cpu's and
+                 * there is no imbalance between this and busiest group
+                 * wrt to idle cpu's, it is balanced.
+                 */
+                if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) &&
+                    sds.busiest_nr_running <= sds.busiest_group_weight)
+                        goto out_balanced;
+        } else {
+                /*
+                 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
+                 * imbalance_pct to be conservative.
+                 */
+                if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load)
+                        goto out_balanced;
+        }
+
+force_balance:
+        /* Looks like there is an imbalance. Compute it */
+        calculate_imbalance(&sds, this_cpu, imbalance);
+        return sds.busiest;
+
+out_balanced:
+        /*
+         * There is no obvious imbalance. But check if we can do some balancing
+         * to save power.
+         */
+        if (check_power_save_busiest_group(&sds, this_cpu, imbalance))
+                return sds.busiest;
+ret:
+        *imbalance = 0;
+        return NULL;
+}
+
+/*
+ * find_busiest_queue - find the busiest runqueue among the cpus in group.
+ */
+static struct rq *
+find_busiest_queue(struct sched_domain *sd, struct sched_group *group,
+                   enum cpu_idle_type idle, unsigned long imbalance,
+                   const struct cpumask *cpus)
+{
+        struct rq *busiest = NULL, *rq;
+        unsigned long max_load = 0;
+        int i;
+
+        for_each_cpu(i, sched_group_cpus(group)) {
+                unsigned long power = power_of(i);
+                unsigned long capacity = DIV_ROUND_CLOSEST(power,
+                                                           SCHED_POWER_SCALE);
+                unsigned long wl;
+
+                if (!capacity)
+                        capacity = fix_small_capacity(sd, group);
+
+                if (!cpumask_test_cpu(i, cpus))
+                        continue;
+
+                rq = cpu_rq(i);
+                wl = weighted_cpuload(i);
+
+                /*
+                 * When comparing with imbalance, use weighted_cpuload()
+                 * which is not scaled with the cpu power.
+                 */
+                if (capacity && rq->nr_running == 1 && wl > imbalance)
+                        continue;
+
+                /*
+                 * For the load comparisons with the other cpu's, consider
+                 * the weighted_cpuload() scaled with the cpu power, so that
+                 * the load can be moved away from the cpu that is potentially
+                 * running at a lower capacity.
+                 */
+                wl = (wl * SCHED_POWER_SCALE) / power;
+
+                if (wl > max_load) {
+                        max_load = wl;
+                        busiest = rq;
+                }
+        }
+
+        return busiest;
+}
+
+/*
+ * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
+ * so long as it is large enough.
+ */
+#define MAX_PINNED_INTERVAL     512
+
+/* Working cpumask for load_balance and load_balance_newidle. */
+static DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
+
+static int need_active_balance(struct sched_domain *sd, int idle,
+                               int busiest_cpu, int this_cpu)
+{
+        if (idle == CPU_NEWLY_IDLE) {
+
+                /*
+                 * ASYM_PACKING needs to force migrate tasks from busy but
+                 * higher numbered CPUs in order to pack all tasks in the
+                 * lowest numbered CPUs.
+                 */
+                if ((sd->flags & SD_ASYM_PACKING) && busiest_cpu > this_cpu)
+                        return 1;
+
+                /*
+                 * The only task running in a non-idle cpu can be moved to this
+                 * cpu in an attempt to completely freeup the other CPU
+                 * package.
+                 *
+                 * The package power saving logic comes from
+                 * find_busiest_group(). If there are no imbalance, then
+                 * f_b_g() will return NULL. However when sched_mc={1,2} then
+                 * f_b_g() will select a group from which a running task may be
+                 * pulled to this cpu in order to make the other package idle.
+                 * If there is no opportunity to make a package idle and if
+                 * there are no imbalance, then f_b_g() will return NULL and no
+                 * action will be taken in load_balance_newidle().
+                 *
+                 * Under normal task pull operation due to imbalance, there
+                 * will be more than one task in the source run queue and
+                 * move_tasks() will succeed.  ld_moved will be true and this
+                 * active balance code will not be triggered.
+                 */
+                if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP)
+                        return 0;
+        }
+
+        return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
+}
+
+static int active_load_balance_cpu_stop(void *data);
+
+/*
+ * Check this_cpu to ensure it is balanced within domain. Attempt to move
+ * tasks if there is an imbalance.
+ */
+static int load_balance(int this_cpu, struct rq *this_rq,
+                        struct sched_domain *sd, enum cpu_idle_type idle,
+                        int *balance)
+{
+        int ld_moved, all_pinned = 0, active_balance = 0;
+        struct sched_group *group;
+        unsigned long imbalance;
+        struct rq *busiest;
+        unsigned long flags;
+        struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
+
+        cpumask_copy(cpus, cpu_active_mask);
+
+        schedstat_inc(sd, lb_count[idle]);
+
+redo:
+        group = find_busiest_group(sd, this_cpu, &imbalance, idle,
+                                   cpus, balance);
+
+        if (*balance == 0)
+                goto out_balanced;
+
+        if (!group) {
+                schedstat_inc(sd, lb_nobusyg[idle]);
+                goto out_balanced;
+        }
+
+        busiest = find_busiest_queue(sd, group, idle, imbalance, cpus);
+        if (!busiest) {
+                schedstat_inc(sd, lb_nobusyq[idle]);
+                goto out_balanced;
+        }
+
+        BUG_ON(busiest == this_rq);
+
+        schedstat_add(sd, lb_imbalance[idle], imbalance);
+
+        ld_moved = 0;
+        if (busiest->nr_running > 1) {
+                /*
+                 * Attempt to move tasks. If find_busiest_group has found
+                 * an imbalance but busiest->nr_running <= 1, the group is
+                 * still unbalanced. ld_moved simply stays zero, so it is
+                 * correctly treated as an imbalance.
+                 */
+                all_pinned = 1;
+                local_irq_save(flags);
+                double_rq_lock(this_rq, busiest);
+                ld_moved = move_tasks(this_rq, this_cpu, busiest,
+                                      imbalance, sd, idle, &all_pinned);
+                double_rq_unlock(this_rq, busiest);
+                local_irq_restore(flags);
+
+                /*
+                 * some other cpu did the load balance for us.
+                 */
+                if (ld_moved && this_cpu != smp_processor_id())
+                        resched_cpu(this_cpu);
+
+                /* All tasks on this runqueue were pinned by CPU affinity */
+                if (unlikely(all_pinned)) {
+                        cpumask_clear_cpu(cpu_of(busiest), cpus);
+                        if (!cpumask_empty(cpus))
+                                goto redo;
+                        goto out_balanced;
+                }
+        }
+
+        if (!ld_moved) {
+                schedstat_inc(sd, lb_failed[idle]);
+                /*
+                 * Increment the failure counter only on periodic balance.
+                 * We do not want newidle balance, which can be very
+                 * frequent, pollute the failure counter causing
+                 * excessive cache_hot migrations and active balances.
+                 */
+                if (idle != CPU_NEWLY_IDLE)
+                        sd->nr_balance_failed++;
+
+                if (need_active_balance(sd, idle, cpu_of(busiest), this_cpu)) {
+                        raw_spin_lock_irqsave(&busiest->lock, flags);
+
+                        /* don't kick the active_load_balance_cpu_stop,
+                         * if the curr task on busiest cpu can't be
+                         * moved to this_cpu
+                         */
+                        if (!cpumask_test_cpu(this_cpu,
+                                              &busiest->curr->cpus_allowed)) {
+                                raw_spin_unlock_irqrestore(&busiest->lock,
+                                                            flags);
+                                all_pinned = 1;
+                                goto out_one_pinned;
+                        }
+
+                        /*
+                         * ->active_balance synchronizes accesses to
+                         * ->active_balance_work.  Once set, it's cleared
+                         * only after active load balance is finished.
+                         */
+                        if (!busiest->active_balance) {
+                                busiest->active_balance = 1;
+                                busiest->push_cpu = this_cpu;
+                                active_balance = 1;
+                        }
+                        raw_spin_unlock_irqrestore(&busiest->lock, flags);
+
+                        if (active_balance)
+                                stop_one_cpu_nowait(cpu_of(busiest),
+                                        active_load_balance_cpu_stop, busiest,
+                                        &busiest->active_balance_work);
+
+                        /*
+                         * We've kicked active balancing, reset the failure
+                         * counter.
+                         */
+                        sd->nr_balance_failed = sd->cache_nice_tries+1;
+                }
+        } else
+                sd->nr_balance_failed = 0;
+
+        if (likely(!active_balance)) {
+                /* We were unbalanced, so reset the balancing interval */
+                sd->balance_interval = sd->min_interval;
+        } else {
+                /*
+                 * If we've begun active balancing, start to back off. This
+                 * case may not be covered by the all_pinned logic if there
+                 * is only 1 task on the busy runqueue (because we don't call
+                 * move_tasks).
+                 */
+                if (sd->balance_interval < sd->max_interval)
+                        sd->balance_interval *= 2;
+        }
+
+        goto out;
+
+out_balanced:
+        schedstat_inc(sd, lb_balanced[idle]);
+
+        sd->nr_balance_failed = 0;
+
+out_one_pinned:
+        /* tune up the balancing interval */
+        if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
+                        (sd->balance_interval < sd->max_interval))
+                sd->balance_interval *= 2;
+
+        ld_moved = 0;
+out:
+        return ld_moved;
+}
+
+/*
+ * idle_balance is called by schedule() if this_cpu is about to become
+ * idle. Attempts to pull tasks from other CPUs.
+ */
+static void idle_balance(int this_cpu, struct rq *this_rq)
+{
+        struct sched_domain *sd;
+        int pulled_task = 0;
+        unsigned long next_balance = jiffies + HZ;
+
+        this_rq->idle_stamp = this_rq->clock;
+
+        if (this_rq->avg_idle < sysctl_sched_migration_cost)
+                return;
+
+        /*
+         * Drop the rq->lock, but keep IRQ/preempt disabled.
+         */
+        raw_spin_unlock(&this_rq->lock);
+
+        update_shares(this_cpu);
+        rcu_read_lock();
+        for_each_domain(this_cpu, sd) {
+                unsigned long interval;
+                int balance = 1;
+
+                if (!(sd->flags & SD_LOAD_BALANCE))
+                        continue;
+
+                if (sd->flags & SD_BALANCE_NEWIDLE) {
+                        /* If we've pulled tasks over stop searching: */
+                        pulled_task = load_balance(this_cpu, this_rq,
+                                                   sd, CPU_NEWLY_IDLE, &balance);
+                }
+
+                interval = msecs_to_jiffies(sd->balance_interval);
+                if (time_after(next_balance, sd->last_balance + interval))
+                        next_balance = sd->last_balance + interval;
+                if (pulled_task) {
+                        this_rq->idle_stamp = 0;
+                        break;
+                }
+        }
+        rcu_read_unlock();
+
+        raw_spin_lock(&this_rq->lock);
+
+        if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
+                /*
+                 * We are going idle. next_balance may be set based on
+                 * a busy processor. So reset next_balance.
+                 */
+                this_rq->next_balance = next_balance;
+        }
+}
+
+/*
+ * active_load_balance_cpu_stop is run by cpu stopper. It pushes
+ * running tasks off the busiest CPU onto idle CPUs. It requires at
+ * least 1 task to be running on each physical CPU where possible, and
+ * avoids physical / logical imbalances.
+ */
+static int active_load_balance_cpu_stop(void *data)
+{
+        struct rq *busiest_rq = data;
+        int busiest_cpu = cpu_of(busiest_rq);
+        int target_cpu = busiest_rq->push_cpu;
+        struct rq *target_rq = cpu_rq(target_cpu);
+        struct sched_domain *sd;
+
+        raw_spin_lock_irq(&busiest_rq->lock);
+
+        /* make sure the requested cpu hasn't gone down in the meantime */
+        if (unlikely(busiest_cpu != smp_processor_id() ||
+                     !busiest_rq->active_balance))
+                goto out_unlock;
+
+        /* Is there any task to move? */
+        if (busiest_rq->nr_running <= 1)
+                goto out_unlock;
+
+        /*
+         * This condition is "impossible", if it occurs
+         * we need to fix it. Originally reported by
+         * Bjorn Helgaas on a 128-cpu setup.
+         */
+        BUG_ON(busiest_rq == target_rq);
+
+        /* move a task from busiest_rq to target_rq */
+        double_lock_balance(busiest_rq, target_rq);
+
+        /* Search for an sd spanning us and the target CPU. */
+        rcu_read_lock();
+        for_each_domain(target_cpu, sd) {
+                if ((sd->flags & SD_LOAD_BALANCE) &&
+                    cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
+                                break;
+        }
+
+        if (likely(sd)) {
+                schedstat_inc(sd, alb_count);
+
+                if (move_one_task(target_rq, target_cpu, busiest_rq,
+                                  sd, CPU_IDLE))
+                        schedstat_inc(sd, alb_pushed);
+                else
+                        schedstat_inc(sd, alb_failed);
+        }
+        rcu_read_unlock();
+        double_unlock_balance(busiest_rq, target_rq);
+out_unlock:
+        busiest_rq->active_balance = 0;
+        raw_spin_unlock_irq(&busiest_rq->lock);
+        return 0;
+}
+
+#ifdef CONFIG_NO_HZ
+
+static DEFINE_PER_CPU(struct call_single_data, remote_sched_softirq_cb);
+
+static void trigger_sched_softirq(void *data)
+{
+        raise_softirq_irqoff(SCHED_SOFTIRQ);
+}
+
+static inline void init_sched_softirq_csd(struct call_single_data *csd)
+{
+        csd->func = trigger_sched_softirq;
+        csd->info = NULL;
+        csd->flags = 0;
+        csd->priv = 0;
+}
+
+/*
+ * idle load balancing details
+ * - One of the idle CPUs nominates itself as idle load_balancer, while
+ *   entering idle.
+ * - This idle load balancer CPU will also go into tickless mode when
+ *   it is idle, just like all other idle CPUs
+ * - When one of the busy CPUs notice that there may be an idle rebalancing
+ *   needed, they will kick the idle load balancer, which then does idle
+ *   load balancing for all the idle CPUs.
+ */
+static struct {
+        atomic_t load_balancer;
+        atomic_t first_pick_cpu;
+        atomic_t second_pick_cpu;
+        cpumask_var_t idle_cpus_mask;
+        cpumask_var_t grp_idle_mask;
+        unsigned long next_balance;     /* in jiffy units */
+} nohz ____cacheline_aligned;
+
+int get_nohz_load_balancer(void)
+{
+        return atomic_read(&nohz.load_balancer);
+}
+
+#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
+/**
+ * lowest_flag_domain - Return lowest sched_domain containing flag.
+ * @cpu:        The cpu whose lowest level of sched domain is to
+ *              be returned.
+ * @flag:       The flag to check for the lowest sched_domain
+ *              for the given cpu.
+ *
+ * Returns the lowest sched_domain of a cpu which contains the given flag.
+ */
+static inline struct sched_domain *lowest_flag_domain(int cpu, int flag)
+{
+        struct sched_domain *sd;
+
+        for_each_domain(cpu, sd)
+                if (sd && (sd->flags & flag))
+                        break;
+
+        return sd;
+}
+
+/**
+ * for_each_flag_domain - Iterates over sched_domains containing the flag.
+ * @cpu:        The cpu whose domains we're iterating over.
+ * @sd:         variable holding the value of the power_savings_sd
+ *              for cpu.
+ * @flag:       The flag to filter the sched_domains to be iterated.
+ *
+ * Iterates over all the scheduler domains for a given cpu that has the 'flag'
+ * set, starting from the lowest sched_domain to the highest.
+ */
+#define for_each_flag_domain(cpu, sd, flag) \
+        for (sd = lowest_flag_domain(cpu, flag); \
+                (sd && (sd->flags & flag)); sd = sd->parent)
+
+/**
+ * is_semi_idle_group - Checks if the given sched_group is semi-idle.
+ * @ilb_group:  group to be checked for semi-idleness
+ *
+ * Returns:     1 if the group is semi-idle. 0 otherwise.
+ *
+ * We define a sched_group to be semi idle if it has atleast one idle-CPU
+ * and atleast one non-idle CPU. This helper function checks if the given
+ * sched_group is semi-idle or not.
+ */
+static inline int is_semi_idle_group(struct sched_group *ilb_group)
+{
+        cpumask_and(nohz.grp_idle_mask, nohz.idle_cpus_mask,
+                                        sched_group_cpus(ilb_group));
+
+        /*
+         * A sched_group is semi-idle when it has atleast one busy cpu
+         * and atleast one idle cpu.
+         */
+        if (cpumask_empty(nohz.grp_idle_mask))
+                return 0;
+
+        if (cpumask_equal(nohz.grp_idle_mask, sched_group_cpus(ilb_group)))
+                return 0;
+
+        return 1;
+}
+/**
+ * find_new_ilb - Finds the optimum idle load balancer for nomination.
+ * @cpu:        The cpu which is nominating a new idle_load_balancer.
+ *
+ * Returns:     Returns the id of the idle load balancer if it exists,
+ *              Else, returns >= nr_cpu_ids.
+ *
+ * This algorithm picks the idle load balancer such that it belongs to a
+ * semi-idle powersavings sched_domain. The idea is to try and avoid
+ * completely idle packages/cores just for the purpose of idle load balancing
+ * when there are other idle cpu's which are better suited for that job.
+ */
+static int find_new_ilb(int cpu)
+{
+        struct sched_domain *sd;
+        struct sched_group *ilb_group;
+        int ilb = nr_cpu_ids;
+
+        /*
+         * Have idle load balancer selection from semi-idle packages only
+         * when power-aware load balancing is enabled
+         */
+        if (!(sched_smt_power_savings || sched_mc_power_savings))
+                goto out_done;
+
+        /*
+         * Optimize for the case when we have no idle CPUs or only one
+         * idle CPU. Don't walk the sched_domain hierarchy in such cases
+         */
+        if (cpumask_weight(nohz.idle_cpus_mask) < 2)
+                goto out_done;
+
+        rcu_read_lock();
+        for_each_flag_domain(cpu, sd, SD_POWERSAVINGS_BALANCE) {
+                ilb_group = sd->groups;
+
+                do {
+                        if (is_semi_idle_group(ilb_group)) {
+                                ilb = cpumask_first(nohz.grp_idle_mask);
+                                goto unlock;
+                        }
+
+                        ilb_group = ilb_group->next;
+
+                } while (ilb_group != sd->groups);
+        }
+unlock:
+        rcu_read_unlock();
+
+out_done:
+        return ilb;
+}
+#else /*  (CONFIG_SCHED_MC || CONFIG_SCHED_SMT) */
+static inline int find_new_ilb(int call_cpu)
+{
+        return nr_cpu_ids;
+}
+#endif
+
+/*
+ * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
+ * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
+ * CPU (if there is one).
+ */
+static void nohz_balancer_kick(int cpu)
+{
+        int ilb_cpu;
+
+        nohz.next_balance++;
+
+        ilb_cpu = get_nohz_load_balancer();
+
+        if (ilb_cpu >= nr_cpu_ids) {
+                ilb_cpu = cpumask_first(nohz.idle_cpus_mask);
+                if (ilb_cpu >= nr_cpu_ids)
+                        return;
+        }
+
+        if (!cpu_rq(ilb_cpu)->nohz_balance_kick) {
+                struct call_single_data *cp;
+
+                cpu_rq(ilb_cpu)->nohz_balance_kick = 1;
+                cp = &per_cpu(remote_sched_softirq_cb, cpu);
+                __smp_call_function_single(ilb_cpu, cp, 0);
+        }
+        return;
+}
+
+/*
+ * This routine will try to nominate the ilb (idle load balancing)
+ * owner among the cpus whose ticks are stopped. ilb owner will do the idle
+ * load balancing on behalf of all those cpus.
+ *
+ * When the ilb owner becomes busy, we will not have new ilb owner until some
+ * idle CPU wakes up and goes back to idle or some busy CPU tries to kick
+ * idle load balancing by kicking one of the idle CPUs.
+ *
+ * Ticks are stopped for the ilb owner as well, with busy CPU kicking this
+ * ilb owner CPU in future (when there is a need for idle load balancing on
+ * behalf of all idle CPUs).
+ */
+void select_nohz_load_balancer(int stop_tick)
+{
+        int cpu = smp_processor_id();
+
+        if (stop_tick) {
+                if (!cpu_active(cpu)) {
+                        if (atomic_read(&nohz.load_balancer) != cpu)
+                                return;
+
+                        /*
+                         * If we are going offline and still the leader,
+                         * give up!
+                         */
+                        if (atomic_cmpxchg(&nohz.load_balancer, cpu,
+                                           nr_cpu_ids) != cpu)
+                                BUG();
+
+                        return;
+                }
+
+                cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
+
+                if (atomic_read(&nohz.first_pick_cpu) == cpu)
+                        atomic_cmpxchg(&nohz.first_pick_cpu, cpu, nr_cpu_ids);
+                if (atomic_read(&nohz.second_pick_cpu) == cpu)
+                        atomic_cmpxchg(&nohz.second_pick_cpu, cpu, nr_cpu_ids);
+
+                if (atomic_read(&nohz.load_balancer) >= nr_cpu_ids) {
+                        int new_ilb;
+
+                        /* make me the ilb owner */
+                        if (atomic_cmpxchg(&nohz.load_balancer, nr_cpu_ids,
+                                           cpu) != nr_cpu_ids)
+                                return;
+
+                        /*
+                         * Check to see if there is a more power-efficient
+                         * ilb.
+                         */
+                        new_ilb = find_new_ilb(cpu);
+                        if (new_ilb < nr_cpu_ids && new_ilb != cpu) {
+                                atomic_set(&nohz.load_balancer, nr_cpu_ids);
+                                resched_cpu(new_ilb);
+                                return;
+                        }
+                        return;
+                }
+        } else {
+                if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
+                        return;
+
+                cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
+
+                if (atomic_read(&nohz.load_balancer) == cpu)
+                        if (atomic_cmpxchg(&nohz.load_balancer, cpu,
+                                           nr_cpu_ids) != cpu)
+                                BUG();
+        }
+        return;
+}
+#endif
+
+static DEFINE_SPINLOCK(balancing);
+
+static unsigned long __read_mostly max_load_balance_interval = HZ/10;
+
+/*
+ * Scale the max load_balance interval with the number of CPUs in the system.
+ * This trades load-balance latency on larger machines for less cross talk.
+ */
+static void update_max_interval(void)
+{
+        max_load_balance_interval = HZ*num_online_cpus()/10;
+}
+
+/*
+ * It checks each scheduling domain to see if it is due to be balanced,
+ * and initiates a balancing operation if so.
+ *
+ * Balancing parameters are set up in arch_init_sched_domains.
+ */
+static void rebalance_domains(int cpu, enum cpu_idle_type idle)
+{
+        int balance = 1;
+        struct rq *rq = cpu_rq(cpu);
+        unsigned long interval;
+        struct sched_domain *sd;
+        /* Earliest time when we have to do rebalance again */
+        unsigned long next_balance = jiffies + 60*HZ;
+        int update_next_balance = 0;
+        int need_serialize;
+
+        update_shares(cpu);
+
+        rcu_read_lock();
+        for_each_domain(cpu, sd) {
+                if (!(sd->flags & SD_LOAD_BALANCE))
+                        continue;
+
+                interval = sd->balance_interval;
+                if (idle != CPU_IDLE)
+                        interval *= sd->busy_factor;
+
+                /* scale ms to jiffies */
+                interval = msecs_to_jiffies(interval);
+                interval = clamp(interval, 1UL, max_load_balance_interval);
+
+                need_serialize = sd->flags & SD_SERIALIZE;
+
+                if (need_serialize) {
+                        if (!spin_trylock(&balancing))
+                                goto out;
+                }
+
+                if (time_after_eq(jiffies, sd->last_balance + interval)) {
+                        if (load_balance(cpu, rq, sd, idle, &balance)) {
+                                /*
+                                 * We've pulled tasks over so either we're no
+                                 * longer idle.
+                                 */
+                                idle = CPU_NOT_IDLE;
+                        }
+                        sd->last_balance = jiffies;
+                }
+                if (need_serialize)
+                        spin_unlock(&balancing);
+out:
+                if (time_after(next_balance, sd->last_balance + interval)) {
+                        next_balance = sd->last_balance + interval;
+                        update_next_balance = 1;
+                }
+
+                /*
+                 * Stop the load balance at this level. There is another
+                 * CPU in our sched group which is doing load balancing more
+                 * actively.
+                 */
+                if (!balance)
+                        break;
+        }
+        rcu_read_unlock();
+
+        /*
+         * next_balance will be updated only when there is a need.
+         * When the cpu is attached to null domain for ex, it will not be
+         * updated.
+         */
+        if (likely(update_next_balance))
+                rq->next_balance = next_balance;
+}
+
+#ifdef CONFIG_NO_HZ
+/*
+ * In CONFIG_NO_HZ case, the idle balance kickee will do the
+ * rebalancing for all the cpus for whom scheduler ticks are stopped.
+ */
+static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle)
+{
+        struct rq *this_rq = cpu_rq(this_cpu);
+        struct rq *rq;
+        int balance_cpu;
+
+        if (idle != CPU_IDLE || !this_rq->nohz_balance_kick)
+                return;
+
+        for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
+                if (balance_cpu == this_cpu)
+                        continue;
+
+                /*
+                 * If this cpu gets work to do, stop the load balancing
+                 * work being done for other cpus. Next load
+                 * balancing owner will pick it up.
+                 */
+                if (need_resched()) {
+                        this_rq->nohz_balance_kick = 0;
+                        break;
+                }
+
+                raw_spin_lock_irq(&this_rq->lock);
+                update_rq_clock(this_rq);
+                update_cpu_load(this_rq);
+                raw_spin_unlock_irq(&this_rq->lock);
+
+                rebalance_domains(balance_cpu, CPU_IDLE);
+
+                rq = cpu_rq(balance_cpu);
+                if (time_after(this_rq->next_balance, rq->next_balance))
+                        this_rq->next_balance = rq->next_balance;
+        }
+        nohz.next_balance = this_rq->next_balance;
+        this_rq->nohz_balance_kick = 0;
+}
+
+/*
+ * Current heuristic for kicking the idle load balancer
+ * - first_pick_cpu is the one of the busy CPUs. It will kick
+ *   idle load balancer when it has more than one process active. This
+ *   eliminates the need for idle load balancing altogether when we have
+ *   only one running process in the system (common case).
+ * - If there are more than one busy CPU, idle load balancer may have
+ *   to run for active_load_balance to happen (i.e., two busy CPUs are
+ *   SMT or core siblings and can run better if they move to different
+ *   physical CPUs). So, second_pick_cpu is the second of the busy CPUs
+ *   which will kick idle load balancer as soon as it has any load.
+ */
+static inline int nohz_kick_needed(struct rq *rq, int cpu)
+{
+        unsigned long now = jiffies;
+        int ret;
+        int first_pick_cpu, second_pick_cpu;
+
+        if (time_before(now, nohz.next_balance))
+                return 0;
+
+        if (rq->idle_at_tick)
+                return 0;
+
+        first_pick_cpu = atomic_read(&nohz.first_pick_cpu);
+        second_pick_cpu = atomic_read(&nohz.second_pick_cpu);
+
+        if (first_pick_cpu < nr_cpu_ids && first_pick_cpu != cpu &&
+            second_pick_cpu < nr_cpu_ids && second_pick_cpu != cpu)
+                return 0;
+
+        ret = atomic_cmpxchg(&nohz.first_pick_cpu, nr_cpu_ids, cpu);
+        if (ret == nr_cpu_ids || ret == cpu) {
+                atomic_cmpxchg(&nohz.second_pick_cpu, cpu, nr_cpu_ids);
+                if (rq->nr_running > 1)
+                        return 1;
+        } else {
+                ret = atomic_cmpxchg(&nohz.second_pick_cpu, nr_cpu_ids, cpu);
+                if (ret == nr_cpu_ids || ret == cpu) {
+                        if (rq->nr_running)
+                                return 1;
+                }
+        }
+        return 0;
+}
+#else
+static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { }
+#endif
+
+/*
+ * run_rebalance_domains is triggered when needed from the scheduler tick.
+ * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
+ */
+static void run_rebalance_domains(struct softirq_action *h)
+{
+        int this_cpu = smp_processor_id();
+        struct rq *this_rq = cpu_rq(this_cpu);
+        enum cpu_idle_type idle = this_rq->idle_at_tick ?
+                                                CPU_IDLE : CPU_NOT_IDLE;
+
+        rebalance_domains(this_cpu, idle);
+
+        /*
+         * If this cpu has a pending nohz_balance_kick, then do the
+         * balancing on behalf of the other idle cpus whose ticks are
+         * stopped.
+         */
+        nohz_idle_balance(this_cpu, idle);
+}
+
+static inline int on_null_domain(int cpu)
+{
+        return !rcu_dereference_sched(cpu_rq(cpu)->sd);
+}
+
+/*
+ * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
+ */
+static inline void trigger_load_balance(struct rq *rq, int cpu)
+{
+        /* Don't need to rebalance while attached to NULL domain */
+        if (time_after_eq(jiffies, rq->next_balance) &&
+            likely(!on_null_domain(cpu)))
+                raise_softirq(SCHED_SOFTIRQ);
+#ifdef CONFIG_NO_HZ
+        else if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu)))
+                nohz_balancer_kick(cpu);
+#endif
+}
+
+static void rq_online_fair(struct rq *rq)
+{
+        update_sysctl();
+}
+
+static void rq_offline_fair(struct rq *rq)
+{
+        update_sysctl();
+}
+
+#else   /* CONFIG_SMP */
+
+/*
+ * on UP we do not need to balance between CPUs:
+ */
+static inline void idle_balance(int cpu, struct rq *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);
+        }
+}
+
+/*
+ * called on fork with the child task as argument from the parent's context
+ *  - child not yet on the tasklist
+ *  - preemption disabled
+ */
+static void task_fork_fair(struct task_struct *p)
+{
+        struct cfs_rq *cfs_rq = task_cfs_rq(current);
+        struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
+        int this_cpu = smp_processor_id();
+        struct rq *rq = this_rq();
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&rq->lock, flags);
+
+        update_rq_clock(rq);
+
+        if (unlikely(task_cpu(p) != this_cpu)) {
+                rcu_read_lock();
+                __set_task_cpu(p, this_cpu);
+                rcu_read_unlock();
+        }
+
+        update_curr(cfs_rq);
+
+        if (curr)
+                se->vruntime = curr->vruntime;
+        place_entity(cfs_rq, se, 1);
+
+        if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
+                /*
+                 * Upon rescheduling, sched_class::put_prev_task() will place
+                 * 'current' within the tree based on its new key value.
+                 */
+                swap(curr->vruntime, se->vruntime);
+                resched_task(rq->curr);
+        }
+
+        se->vruntime -= cfs_rq->min_vruntime;
+
+        raw_spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+/*
+ * Priority of the task has changed. Check to see if we preempt
+ * the current task.
+ */
+static void
+prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
+{
+        if (!p->se.on_rq)
+                return;
+
+        /*
+         * Reschedule if we are currently running on this runqueue and
+         * our priority decreased, or if we are not currently running on
+         * this runqueue and our priority is higher than the current's
+         */
+        if (rq->curr == p) {
+                if (p->prio > oldprio)
+                        resched_task(rq->curr);
+        } else
+                check_preempt_curr(rq, p, 0);
+}
+
+static void switched_from_fair(struct rq *rq, struct task_struct *p)
+{
+        struct sched_entity *se = &p->se;
+        struct cfs_rq *cfs_rq = cfs_rq_of(se);
+
+        /*
+         * Ensure the task's vruntime is normalized, so that when its
+         * switched back to the fair class the enqueue_entity(.flags=0) will
+         * do the right thing.
+         *
+         * If it was on_rq, then the dequeue_entity(.flags=0) will already
+         * have normalized the vruntime, if it was !on_rq, then only when
+         * the task is sleeping will it still have non-normalized vruntime.
+         */
+        if (!se->on_rq && p->state != TASK_RUNNING) {
+                /*
+                 * Fix up our vruntime so that the current sleep doesn't
+                 * cause 'unlimited' sleep bonus.
+                 */
+                place_entity(cfs_rq, se, 0);
+                se->vruntime -= cfs_rq->min_vruntime;
+        }
+}
+
+/*
+ * We switched to the sched_fair class.
+ */
+static void switched_to_fair(struct rq *rq, struct task_struct *p)
+{
+        if (!p->se.on_rq)
+                return;
+
+        /*
+         * We were most likely switched from sched_rt, so
+         * kick off the schedule if running, otherwise just see
+         * if we can still preempt the current task.
+         */
+        if (rq->curr == p)
+                resched_task(rq->curr);
+        else
+                check_preempt_curr(rq, p, 0);
+}
+
+/* Account for a task changing its policy or group.
+ *
+ * This routine is mostly called to set cfs_rq->curr field when a task
+ * migrates between groups/classes.
+ */
+static void set_curr_task_fair(struct rq *rq)
+{
+        struct sched_entity *se = &rq->curr->se;
+
+        for_each_sched_entity(se)
+                set_next_entity(cfs_rq_of(se), se);
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static void task_move_group_fair(struct task_struct *p, int on_rq)
+{
+        /*
+         * If the task was not on the rq at the time of this cgroup movement
+         * it must have been asleep, sleeping tasks keep their ->vruntime
+         * absolute on their old rq until wakeup (needed for the fair sleeper
+         * bonus in place_entity()).
+         *
+         * If it was on the rq, we've just 'preempted' it, which does convert
+         * ->vruntime to a relative base.
+         *
+         * Make sure both cases convert their relative position when migrating
+         * to another cgroup's rq. This does somewhat interfere with the
+         * fair sleeper stuff for the first placement, but who cares.
+         */
+        if (!on_rq)
+                p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime;
+        set_task_rq(p, task_cpu(p));
+        if (!on_rq)
+                p->se.vruntime += cfs_rq_of(&p->se)->min_vruntime;
+}
+#endif
+
+static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
+{
+        struct sched_entity *se = &task->se;
+        unsigned int rr_interval = 0;
+
+        /*
+         * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
+         * idle runqueue:
+         */
+        if (rq->cfs.load.weight)
+                rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
+
+        return rr_interval;
+}
+
+/*
+ * All the scheduling class methods:
+ */
+static const struct sched_class fair_sched_class = {
+        .next                   = &idle_sched_class,
+        .enqueue_task           = enqueue_task_fair,
+        .dequeue_task           = dequeue_task_fair,
+        .yield_task             = yield_task_fair,
+        .yield_to_task          = yield_to_task_fair,
+
+        .check_preempt_curr     = check_preempt_wakeup,
+
+        .pick_next_task         = pick_next_task_fair,
+        .put_prev_task          = put_prev_task_fair,
+
+#ifdef CONFIG_SMP
+        .select_task_rq         = select_task_rq_fair,
+
+        .rq_online              = rq_online_fair,
+        .rq_offline             = rq_offline_fair,
+
+        .task_waking            = task_waking_fair,
+#endif
+
+        .set_curr_task          = set_curr_task_fair,
+        .task_tick              = task_tick_fair,
+        .task_fork              = task_fork_fair,
+
+        .prio_changed           = prio_changed_fair,
+        .switched_from          = switched_from_fair,
+        .switched_to            = switched_to_fair,
+
+        .get_rr_interval        = get_rr_interval_fair,
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+        .task_move_group        = task_move_group_fair,
+#endif
+};
+
+#ifdef CONFIG_SCHED_DEBUG
+static 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