sched: Move load balance code into sched_fair.c

Straight fwd code movement.

Since non of the load-balance abstractions are used anymore, do away with
them and simplify the code some. In preparation move the code around.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 79 insertions, 1840 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 64298a52eaa6..13a2acf18b2d 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1805,6 +1805,51 @@ static inline void double_unlock_balance(struct rq *this_rq, struct rq *busiest)
         raw_spin_unlock(&busiest->lock);
         lock_set_subclass(&this_rq->lock.dep_map, 0, _RET_IP_);
 }
+
+/*
+ * double_rq_lock - safely lock two runqueues
+ *
+ * Note this does not disable interrupts like task_rq_lock,
+ * you need to do so manually before calling.
+ */
+static void double_rq_lock(struct rq *rq1, struct rq *rq2)
+        __acquires(rq1->lock)
+        __acquires(rq2->lock)
+{
+        BUG_ON(!irqs_disabled());
+        if (rq1 == rq2) {
+                raw_spin_lock(&rq1->lock);
+                __acquire(rq2->lock);   /* Fake it out ;) */
+        } else {
+                if (rq1 < rq2) {
+                        raw_spin_lock(&rq1->lock);
+                        raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
+                } else {
+                        raw_spin_lock(&rq2->lock);
+                        raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
+                }
+        }
+        update_rq_clock(rq1);
+        update_rq_clock(rq2);
+}
+
+/*
+ * double_rq_unlock - safely unlock two runqueues
+ *
+ * Note this does not restore interrupts like task_rq_unlock,
+ * you need to do so manually after calling.
+ */
+static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
+        __releases(rq1->lock)
+        __releases(rq2->lock)
+{
+        raw_spin_unlock(&rq1->lock);
+        if (rq1 != rq2)
+                raw_spin_unlock(&rq2->lock);
+        else
+                __release(rq2->lock);
+}
+
 #endif
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
@@ -1834,18 +1879,14 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
 #endif
 }
 
-#include "sched_stats.h"
-#include "sched_idletask.c"
-#include "sched_fair.c"
-#include "sched_rt.c"
-#ifdef CONFIG_SCHED_DEBUG
-# include "sched_debug.c"
-#endif
+static const struct sched_class rt_sched_class;
 
 #define sched_class_highest (&rt_sched_class)
 #define for_each_class(class) \
    for (class = sched_class_highest; class; class = class->next)
 
+#include "sched_stats.h"
+
 static void inc_nr_running(struct rq *rq)
 {
         rq->nr_running++;
@@ -1912,6 +1953,37 @@ static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep)
 }
 
 /*
+ * activate_task - move a task to the runqueue.
+ */
+static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
+{
+        if (task_contributes_to_load(p))
+                rq->nr_uninterruptible--;
+
+        enqueue_task(rq, p, wakeup);
+        inc_nr_running(rq);
+}
+
+/*
+ * deactivate_task - remove a task from the runqueue.
+ */
+static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep)
+{
+        if (task_contributes_to_load(p))
+                rq->nr_uninterruptible++;
+
+        dequeue_task(rq, p, sleep);
+        dec_nr_running(rq);
+}
+
+#include "sched_idletask.c"
+#include "sched_fair.c"
+#include "sched_rt.c"
+#ifdef CONFIG_SCHED_DEBUG
+# include "sched_debug.c"
+#endif
+
+/*
  * __normal_prio - return the priority that is based on the static prio
  */
 static inline int __normal_prio(struct task_struct *p)
@@ -1957,30 +2029,6 @@ static int effective_prio(struct task_struct *p)
         return p->prio;
 }
 
-/*
- * activate_task - move a task to the runqueue.
- */
-static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
-{
-        if (task_contributes_to_load(p))
-                rq->nr_uninterruptible--;
-
-        enqueue_task(rq, p, wakeup);
-        inc_nr_running(rq);
-}
-
-/*
- * deactivate_task - remove a task from the runqueue.
- */
-static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep)
-{
-        if (task_contributes_to_load(p))
-                rq->nr_uninterruptible++;
-
-        dequeue_task(rq, p, sleep);
-        dec_nr_running(rq);
-}
-
 /**
  * task_curr - is this task currently executing on a CPU?
  * @p: the task in question.
@@ -3088,50 +3136,6 @@ static void update_cpu_load(struct rq *this_rq)
 #ifdef CONFIG_SMP
 
 /*
- * double_rq_lock - safely lock two runqueues
- *
- * Note this does not disable interrupts like task_rq_lock,
- * you need to do so manually before calling.
- */
-static void double_rq_lock(struct rq *rq1, struct rq *rq2)
-        __acquires(rq1->lock)
-        __acquires(rq2->lock)
-{
-        BUG_ON(!irqs_disabled());
-        if (rq1 == rq2) {
-                raw_spin_lock(&rq1->lock);
-                __acquire(rq2->lock);   /* Fake it out ;) */
-        } else {
-                if (rq1 < rq2) {
-                        raw_spin_lock(&rq1->lock);
-                        raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
-                } else {
-                        raw_spin_lock(&rq2->lock);
-                        raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
-                }
-        }
-        update_rq_clock(rq1);
-        update_rq_clock(rq2);
-}
-
-/*
- * double_rq_unlock - safely unlock two runqueues
- *
- * Note this does not restore interrupts like task_rq_unlock,
- * you need to do so manually after calling.
- */
-static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
-        __releases(rq1->lock)
-        __releases(rq2->lock)
-{
-        raw_spin_unlock(&rq1->lock);
-        if (rq1 != rq2)
-                raw_spin_unlock(&rq2->lock);
-        else
-                __release(rq2->lock);
-}
-
-/*
  * sched_exec - execve() is a valuable balancing opportunity, because at
  * this point the task has the smallest effective memory and cache footprint.
  */
@@ -3179,1771 +3183,6 @@ again:
         task_rq_unlock(rq, &flags);
 }
 
-/*
- * 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.nr_failed_migrations_affine);
-                return 0;
-        }
-        *all_pinned = 0;
-
-        if (task_running(rq, p)) {
-                schedstat_inc(p, se.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, 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.nr_forced_migrations);
-                }
-#endif
-                return 1;
-        }
-
-        if (tsk_cache_hot) {
-                schedstat_inc(p, se.nr_failed_migrations_hot);
-                return 0;
-        }
-        return 1;
-}
-
-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,
-              int *this_best_prio, struct rq_iterator *iterator)
-{
-        int loops = 0, pulled = 0, pinned = 0;
-        struct task_struct *p;
-        long rem_load_move = max_load_move;
-
-        if (max_load_move == 0)
-                goto out;
-
-        pinned = 1;
-
-        /*
-         * Start the load-balancing iterator:
-         */
-        p = iterator->start(iterator->arg);
-next:
-        if (!p || loops++ > sysctl_sched_nr_migrate)
-                goto out;
-
-        if ((p->se.load.weight >> 1) > rem_load_move ||
-            !can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
-                p = iterator->next(iterator->arg);
-                goto next;
-        }
-
-        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)
-                goto out;
-#endif
-
-        /*
-         * We only want to steal up to the prescribed amount of weighted load.
-         */
-        if (rem_load_move > 0) {
-                if (p->prio < *this_best_prio)
-                        *this_best_prio = p->prio;
-                p = iterator->next(iterator->arg);
-                goto next;
-        }
-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);
-
-        if (all_pinned)
-                *all_pinned = pinned;
-
-        return max_load_move - rem_load_move;
-}
-
-/*
- * 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)
-{
-        const struct sched_class *class = sched_class_highest;
-        unsigned long total_load_moved = 0;
-        int this_best_prio = this_rq->curr->prio;
-
-        do {
-                total_load_moved +=
-                        class->load_balance(this_rq, this_cpu, busiest,
-                                max_load_move - total_load_moved,
-                                sd, idle, all_pinned, &this_best_prio);
-                class = class->next;
-
-#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;
-#endif
-        } while (class && max_load_move > total_load_moved);
-
-        return total_load_moved > 0;
-}
-
-static int
-iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
-                   struct sched_domain *sd, enum cpu_idle_type idle,
-                   struct rq_iterator *iterator)
-{
-        struct task_struct *p = iterator->start(iterator->arg);
-        int pinned = 0;
-
-        while (p) {
-                if (can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
-                        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;
-                }
-                p = iterator->next(iterator->arg);
-        }
-
-        return 0;
-}
-
-/*
- * 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)
-{
-        const struct sched_class *class;
-
-        for_each_class(class) {
-                if (class->move_one_task(this_rq, this_cpu, busiest, sd, idle))
-                        return 1;
-        }
-
-        return 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;
-
-        /* Statistics of the busiest group */
-        unsigned long max_load;
-        unsigned long busiest_load_per_task;
-        unsigned long busiest_nr_running;
-
-        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;
-        int group_imb; /* Is there an imbalance 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_LOAD_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 = cpumask_weight(sched_domain_span(sd));
-        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;
-
-        sched_avg_update(rq);
-
-        total = sched_avg_period() + (rq->clock - rq->age_stamp);
-        available = total - rq->rt_avg;
-
-        if (unlikely((s64)total < SCHED_LOAD_SCALE))
-                total = SCHED_LOAD_SCALE;
-
-        total >>= SCHED_LOAD_SHIFT;
-
-        return div_u64(available, total);
-}
-
-static void update_cpu_power(struct sched_domain *sd, int cpu)
-{
-        unsigned long weight = cpumask_weight(sched_domain_span(sd));
-        unsigned long power = SCHED_LOAD_SCALE;
-        struct sched_group *sdg = sd->groups;
-
-        if (sched_feat(ARCH_POWER))
-                power *= arch_scale_freq_power(sd, cpu);
-        else
-                power *= default_scale_freq_power(sd, cpu);
-
-        power >>= SCHED_LOAD_SHIFT;
-
-        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_LOAD_SHIFT;
-        }
-
-        power *= scale_rt_power(cpu);
-        power >>= SCHED_LOAD_SHIFT;
-
-        if (!power)
-                power = 1;
-
-        sdg->cpu_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->cpu_power;
-                group = group->next;
-        } while (group != child->groups);
-
-        sdg->cpu_power = power;
-}
-
-/**
- * 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.
- * @sd_idle: Idle status of the sched_domain containing group.
- * @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 *sd_idle,
-                        int local_group, const struct cpumask *cpus,
-                        int *balance, struct sg_lb_stats *sgs)
-{
-        unsigned long load, max_cpu_load, min_cpu_load;
-        int i;
-        unsigned int balance_cpu = -1, first_idle_cpu = 0;
-        unsigned long sum_avg_load_per_task;
-        unsigned long avg_load_per_task;
-
-        if (local_group) {
-                balance_cpu = group_first_cpu(group);
-                if (balance_cpu == this_cpu)
-                        update_group_power(sd, this_cpu);
-        }
-
-        /* Tally up the load of all CPUs in the group */
-        sum_avg_load_per_task = avg_load_per_task = 0;
-        max_cpu_load = 0;
-        min_cpu_load = ~0UL;
-
-        for_each_cpu_and(i, sched_group_cpus(group), cpus) {
-                struct rq *rq = cpu_rq(i);
-
-                if (*sd_idle && rq->nr_running)
-                        *sd_idle = 0;
-
-                /* 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;
-                        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);
-
-                sum_avg_load_per_task += cpu_avg_load_per_task(i);
-        }
-
-        /*
-         * 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 &&
-            balance_cpu != this_cpu && balance) {
-                *balance = 0;
-                return;
-        }
-
-        /* Adjust by relative CPU power of the group */
-        sgs->avg_load = (sgs->group_load * SCHED_LOAD_SCALE) / group->cpu_power;
-
-
-        /*
-         * Consider the group unbalanced when the imbalance is larger
-         * than the average weight of two tasks.
-         *
-         * 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?
-         */
-        avg_load_per_task = (sum_avg_load_per_task * SCHED_LOAD_SCALE) /
-                group->cpu_power;
-
-        if ((max_cpu_load - min_cpu_load) > 2*avg_load_per_task)
-                sgs->group_imb = 1;
-
-        sgs->group_capacity =
-                DIV_ROUND_CLOSEST(group->cpu_power, SCHED_LOAD_SCALE);
-}
-
-/**
- * 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
- * @sd_idle: Idle status of the sched_domain containing group.
- * @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, int *sd_idle,
-                        const struct cpumask *cpus, int *balance,
-                        struct sd_lb_stats *sds)
-{
-        struct sched_domain *child = sd->child;
-        struct sched_group *group = 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(group));
-                memset(&sgs, 0, sizeof(sgs));
-                update_sg_lb_stats(sd, group, this_cpu, idle, load_idx, sd_idle,
-                                local_group, cpus, balance, &sgs);
-
-                if (local_group && balance && !(*balance))
-                        return;
-
-                sds->total_load += sgs.group_load;
-                sds->total_pwr += group->cpu_power;
-
-                /*
-                 * In case the child domain prefers tasks go to siblings
-                 * first, lower the group capacity to one so that we'll try
-                 * and move all the excess tasks away.
-                 */
-                if (prefer_sibling)
-                        sgs.group_capacity = min(sgs.group_capacity, 1UL);
-
-                if (local_group) {
-                        sds->this_load = sgs.avg_load;
-                        sds->this = group;
-                        sds->this_nr_running = sgs.sum_nr_running;
-                        sds->this_load_per_task = sgs.sum_weighted_load;
-                } else if (sgs.avg_load > sds->max_load &&
-                           (sgs.sum_nr_running > sgs.group_capacity ||
-                                sgs.group_imb)) {
-                        sds->max_load = sgs.avg_load;
-                        sds->busiest = group;
-                        sds->busiest_nr_running = sgs.sum_nr_running;
-                        sds->busiest_load_per_task = sgs.sum_weighted_load;
-                        sds->group_imb = sgs.group_imb;
-                }
-
-                update_sd_power_savings_stats(group, sds, local_group, &sgs);
-                group = group->next;
-        } while (group != sd->groups);
-}
-
-/**
- * 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;
-
-        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);
-
-        if (sds->max_load - sds->this_load + sds->busiest_load_per_task >=
-                        sds->busiest_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->cpu_power *
-                        min(sds->busiest_load_per_task, sds->max_load);
-        pwr_now += sds->this->cpu_power *
-                        min(sds->this_load_per_task, sds->this_load);
-        pwr_now /= SCHED_LOAD_SCALE;
-
-        /* Amount of load we'd subtract */
-        tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
-                sds->busiest->cpu_power;
-        if (sds->max_load > tmp)
-                pwr_move += sds->busiest->cpu_power *
-                        min(sds->busiest_load_per_task, sds->max_load - tmp);
-
-        /* Amount of load we'd add */
-        if (sds->max_load * sds->busiest->cpu_power <
-                sds->busiest_load_per_task * SCHED_LOAD_SCALE)
-                tmp = (sds->max_load * sds->busiest->cpu_power) /
-                        sds->this->cpu_power;
-        else
-                tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
-                        sds->this->cpu_power;
-        pwr_move += sds->this->cpu_power *
-                        min(sds->this_load_per_task, sds->this_load + tmp);
-        pwr_move /= SCHED_LOAD_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;
-        /*
-         * 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);
-        }
-
-        /* Don't want to pull so many tasks that a group would go idle */
-        max_pull = min(sds->max_load - sds->avg_load,
-                        sds->max_load - sds->busiest_load_per_task);
-
-        /* How much load to actually move to equalise the imbalance */
-        *imbalance = min(max_pull * sds->busiest->cpu_power,
-                (sds->avg_load - sds->this_load) * sds->this->cpu_power)
-                        / SCHED_LOAD_SCALE;
-
-        /*
-         * if *imbalance is less than the average load per runnable task
-         * there is no gaurantee 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.
- * @sd_idle: The idleness of sd
- * @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,
-                   int *sd_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, sd_idle, cpus,
-                                        balance, &sds);
-
-        /* Cases where imbalance does not exist from POV of this_cpu */
-        /* 1) this_cpu is not the appropriate cpu to perform load balancing
-         *    at this level.
-         * 2) There is no busy sibling group to pull from.
-         * 3) This group is the busiest group.
-         * 4) This group is more busy than the avg busieness at this
-         *    sched_domain.
-         * 5) The imbalance is within the specified limit.
-         * 6) Any rebalance would lead to ping-pong
-         */
-        if (balance && !(*balance))
-                goto ret;
-
-        if (!sds.busiest || sds.busiest_nr_running == 0)
-                goto out_balanced;
-
-        if (sds.this_load >= sds.max_load)
-                goto out_balanced;
-
-        sds.avg_load = (SCHED_LOAD_SCALE * sds.total_load) / sds.total_pwr;
-
-        if (sds.this_load >= sds.avg_load)
-                goto out_balanced;
-
-        if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load)
-                goto out_balanced;
-
-        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);
-
-        /*
-         * 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, as either of these
-         * actions would just result in more rebalancing later, and ping-pong
-         * tasks around. Thus we look for the minimum possible imbalance.
-         * Negative imbalances (*we* are more loaded than anyone else) will
-         * be counted as no imbalance for these purposes -- we can't fix that
-         * by pulling tasks to us. Be careful of negative numbers as they'll
-         * appear as very large values with unsigned longs.
-         */
-        if (sds.max_load <= sds.busiest_load_per_task)
-                goto out_balanced;
-
-        /* 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_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_LOAD_SCALE);
-                unsigned long wl;
-
-                if (!cpumask_test_cpu(i, cpus))
-                        continue;
-
-                rq = cpu_rq(i);
-                wl = weighted_cpuload(i) * SCHED_LOAD_SCALE;
-                wl /= power;
-
-                if (capacity && rq->nr_running == 1 && wl > imbalance)
-                        continue;
-
-                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);
-
-/*
- * 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, sd_idle = 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);
-
-        /*
-         * When power savings policy is enabled for the parent domain, idle
-         * sibling can pick up load irrespective of busy siblings. In this case,
-         * let the state of idle sibling percolate up as CPU_IDLE, instead of
-         * portraying it as CPU_NOT_IDLE.
-         */
-        if (idle != CPU_NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
-            !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
-                sd_idle = 1;
-
-        schedstat_inc(sd, lb_count[idle]);
-
-redo:
-        update_shares(sd);
-        group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
-                                   cpus, balance);
-
-        if (*balance == 0)
-                goto out_balanced;
-
-        if (!group) {
-                schedstat_inc(sd, lb_nobusyg[idle]);
-                goto out_balanced;
-        }
-
-        busiest = find_busiest_queue(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.
-                 */
-                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]);
-                sd->nr_balance_failed++;
-
-                if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
-
-                        raw_spin_lock_irqsave(&busiest->lock, flags);
-
-                        /* don't kick the migration_thread, 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;
-                        }
-
-                        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)
-                                wake_up_process(busiest->migration_thread);
-
-                        /*
-                         * 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;
-        }
-
-        if (!ld_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
-            !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
-                ld_moved = -1;
-
-        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;
-
-        if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
-            !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
-                ld_moved = -1;
-        else
-                ld_moved = 0;
-out:
-        if (ld_moved)
-                update_shares(sd);
-        return ld_moved;
-}
-
-/*
- * Check this_cpu to ensure it is balanced within domain. Attempt to move
- * tasks if there is an imbalance.
- *
- * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
- * this_rq is locked.
- */
-static int
-load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd)
-{
-        struct sched_group *group;
-        struct rq *busiest = NULL;
-        unsigned long imbalance;
-        int ld_moved = 0;
-        int sd_idle = 0;
-        int all_pinned = 0;
-        struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
-
-        cpumask_copy(cpus, cpu_active_mask);
-
-        /*
-         * When power savings policy is enabled for the parent domain, idle
-         * sibling can pick up load irrespective of busy siblings. In this case,
-         * let the state of idle sibling percolate up as IDLE, instead of
-         * portraying it as CPU_NOT_IDLE.
-         */
-        if (sd->flags & SD_SHARE_CPUPOWER &&
-            !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
-                sd_idle = 1;
-
-        schedstat_inc(sd, lb_count[CPU_NEWLY_IDLE]);
-redo:
-        update_shares_locked(this_rq, sd);
-        group = find_busiest_group(sd, this_cpu, &imbalance, CPU_NEWLY_IDLE,
-                                   &sd_idle, cpus, NULL);
-        if (!group) {
-                schedstat_inc(sd, lb_nobusyg[CPU_NEWLY_IDLE]);
-                goto out_balanced;
-        }
-
-        busiest = find_busiest_queue(group, CPU_NEWLY_IDLE, imbalance, cpus);
-        if (!busiest) {
-                schedstat_inc(sd, lb_nobusyq[CPU_NEWLY_IDLE]);
-                goto out_balanced;
-        }
-
-        BUG_ON(busiest == this_rq);
-
-        schedstat_add(sd, lb_imbalance[CPU_NEWLY_IDLE], imbalance);
-
-        ld_moved = 0;
-        if (busiest->nr_running > 1) {
-                /* Attempt to move tasks */
-                double_lock_balance(this_rq, busiest);
-                /* this_rq->clock is already updated */
-                update_rq_clock(busiest);
-                ld_moved = move_tasks(this_rq, this_cpu, busiest,
-                                        imbalance, sd, CPU_NEWLY_IDLE,
-                                        &all_pinned);
-                double_unlock_balance(this_rq, busiest);
-
-                if (unlikely(all_pinned)) {
-                        cpumask_clear_cpu(cpu_of(busiest), cpus);
-                        if (!cpumask_empty(cpus))
-                                goto redo;
-                }
-        }
-
-        if (!ld_moved) {
-                int active_balance = 0;
-
-                schedstat_inc(sd, lb_failed[CPU_NEWLY_IDLE]);
-                if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
-                    !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
-                        return -1;
-
-                if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP)
-                        return -1;
-
-                if (sd->nr_balance_failed++ < 2)
-                        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 same method used to move task in load_balance()
-                 * have been extended for load_balance_newidle() to speedup
-                 * consolidation at sched_mc=POWERSAVINGS_BALANCE_WAKEUP (2)
-                 *
-                 * 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.
-                 */
-
-                /* Lock busiest in correct order while this_rq is held */
-                double_lock_balance(this_rq, busiest);
-
-                /*
-                 * don't kick the migration_thread, if the curr
-                 * task on busiest cpu can't be moved to this_cpu
-                 */
-                if (!cpumask_test_cpu(this_cpu, &busiest->curr->cpus_allowed)) {
-                        double_unlock_balance(this_rq, busiest);
-                        all_pinned = 1;
-                        return ld_moved;
-                }
-
-                if (!busiest->active_balance) {
-                        busiest->active_balance = 1;
-                        busiest->push_cpu = this_cpu;
-                        active_balance = 1;
-                }
-
-                double_unlock_balance(this_rq, busiest);
-                /*
-                 * Should not call ttwu while holding a rq->lock
-                 */
-                raw_spin_unlock(&this_rq->lock);
-                if (active_balance)
-                        wake_up_process(busiest->migration_thread);
-                raw_spin_lock(&this_rq->lock);
-
-        } else
-                sd->nr_balance_failed = 0;
-
-        update_shares_locked(this_rq, sd);
-        return ld_moved;
-
-out_balanced:
-        schedstat_inc(sd, lb_balanced[CPU_NEWLY_IDLE]);
-        if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
-            !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
-                return -1;
-        sd->nr_balance_failed = 0;
-
-        return 0;
-}
-
-/*
- * 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;
-
-        for_each_domain(this_cpu, sd) {
-                unsigned long interval;
-
-                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_newidle(this_cpu, this_rq,
-                                                           sd);
-
-                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;
-                }
-        }
-        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 is run by migration threads. 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.
- *
- * Called with busiest_rq locked.
- */
-static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
-{
-        int target_cpu = busiest_rq->push_cpu;
-        struct sched_domain *sd;
-        struct rq *target_rq;
-
-        /* Is there any task to move? */
-        if (busiest_rq->nr_running <= 1)
-                return;
-
-        target_rq = cpu_rq(target_cpu);
-
-        /*
-         * 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);
-        update_rq_clock(busiest_rq);
-        update_rq_clock(target_rq);
-
-        /* Search for an sd spanning us and the target CPU. */
-        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);
-        }
-        double_unlock_balance(busiest_rq, target_rq);
-}
-
-#ifdef CONFIG_NO_HZ
-static struct {
-        atomic_t load_balancer;
-        cpumask_var_t cpu_mask;
-        cpumask_var_t ilb_grp_nohz_mask;
-} nohz ____cacheline_aligned = {
-        .load_balancer = ATOMIC_INIT(-1),
-};
-
-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.ilb_grp_nohz_mask, nohz.cpu_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.ilb_grp_nohz_mask))
-                return 0;
-
-        if (cpumask_equal(nohz.ilb_grp_nohz_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;
-
-        /*
-         * 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.cpu_mask) < 2)
-                goto out_done;
-
-        for_each_flag_domain(cpu, sd, SD_POWERSAVINGS_BALANCE) {
-                ilb_group = sd->groups;
-
-                do {
-                        if (is_semi_idle_group(ilb_group))
-                                return cpumask_first(nohz.ilb_grp_nohz_mask);
-
-                        ilb_group = ilb_group->next;
-
-                } while (ilb_group != sd->groups);
-        }
-
-out_done:
-        return cpumask_first(nohz.cpu_mask);
-}
-#else /*  (CONFIG_SCHED_MC || CONFIG_SCHED_SMT) */
-static inline int find_new_ilb(int call_cpu)
-{
-        return cpumask_first(nohz.cpu_mask);
-}
-#endif
-
-/*
- * 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. If all the cpus in the system
- * go into this tickless mode, then there will be no ilb owner (as there is
- * no need for one) and all the cpus will sleep till the next wakeup event
- * arrives...
- *
- * For the ilb owner, tick is not stopped. And this tick will be used
- * for idle load balancing. ilb owner will still be part of
- * nohz.cpu_mask..
- *
- * While stopping the tick, this cpu will become the ilb owner if there
- * is no other owner. And will be the owner till that cpu becomes busy
- * or if all cpus in the system stop their ticks at which point
- * there is no need for ilb owner.
- *
- * When the ilb owner becomes busy, it nominates another owner, during the
- * next busy scheduler_tick()
- */
-int select_nohz_load_balancer(int stop_tick)
-{
-        int cpu = smp_processor_id();
-
-        if (stop_tick) {
-                cpu_rq(cpu)->in_nohz_recently = 1;
-
-                if (!cpu_active(cpu)) {
-                        if (atomic_read(&nohz.load_balancer) != cpu)
-                                return 0;
-
-                        /*
-                         * If we are going offline and still the leader,
-                         * give up!
-                         */
-                        if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
-                                BUG();
-
-                        return 0;
-                }
-
-                cpumask_set_cpu(cpu, nohz.cpu_mask);
-
-                /* time for ilb owner also to sleep */
-                if (cpumask_weight(nohz.cpu_mask) == num_active_cpus()) {
-                        if (atomic_read(&nohz.load_balancer) == cpu)
-                                atomic_set(&nohz.load_balancer, -1);
-                        return 0;
-                }
-
-                if (atomic_read(&nohz.load_balancer) == -1) {
-                        /* make me the ilb owner */
-                        if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
-                                return 1;
-                } else if (atomic_read(&nohz.load_balancer) == cpu) {
-                        int new_ilb;
-
-                        if (!(sched_smt_power_savings ||
-                                                sched_mc_power_savings))
-                                return 1;
-                        /*
-                         * 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, -1);
-                                resched_cpu(new_ilb);
-                                return 0;
-                        }
-                        return 1;
-                }
-        } else {
-                if (!cpumask_test_cpu(cpu, nohz.cpu_mask))
-                        return 0;
-
-                cpumask_clear_cpu(cpu, nohz.cpu_mask);
-
-                if (atomic_read(&nohz.load_balancer) == cpu)
-                        if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
-                                BUG();
-        }
-        return 0;
-}
-#endif
-
-static DEFINE_SPINLOCK(balancing);
-
-/*
- * 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;
-
-        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);
-                if (unlikely(!interval))
-                        interval = 1;
-                if (interval > HZ*NR_CPUS/10)
-                        interval = HZ*NR_CPUS/10;
-
-                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, or one of our SMT siblings is
-                                 * not 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;
-        }
-
-        /*
-         * 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;
-}
-
-/*
- * run_rebalance_domains is triggered when needed from the scheduler tick.
- * In CONFIG_NO_HZ case, the idle load balance owner will do the
- * rebalancing for all the cpus for whom scheduler ticks are stopped.
- */
-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);
-
-#ifdef CONFIG_NO_HZ
-        /*
-         * If this cpu is the owner for idle load balancing, then do the
-         * balancing on behalf of the other idle cpus whose ticks are
-         * stopped.
-         */
-        if (this_rq->idle_at_tick &&
-            atomic_read(&nohz.load_balancer) == this_cpu) {
-                struct rq *rq;
-                int balance_cpu;
-
-                for_each_cpu(balance_cpu, nohz.cpu_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())
-                                break;
-
-                        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;
-                }
-        }
-#endif
-}
-
-static inline int on_null_domain(int cpu)
-{
-        return !rcu_dereference(cpu_rq(cpu)->sd);
-}
-
-/*
- * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
- *
- * In case of CONFIG_NO_HZ, this is the place where we nominate a new
- * idle load balancing owner or decide to stop the periodic load balancing,
- * if the whole system is idle.
- */
-static inline void trigger_load_balance(struct rq *rq, int cpu)
-{
-#ifdef CONFIG_NO_HZ
-        /*
-         * If we were in the nohz mode recently and busy at the current
-         * scheduler tick, then check if we need to nominate new idle
-         * load balancer.
-         */
-        if (rq->in_nohz_recently && !rq->idle_at_tick) {
-                rq->in_nohz_recently = 0;
-
-                if (atomic_read(&nohz.load_balancer) == cpu) {
-                        cpumask_clear_cpu(cpu, nohz.cpu_mask);
-                        atomic_set(&nohz.load_balancer, -1);
-                }
-
-                if (atomic_read(&nohz.load_balancer) == -1) {
-                        int ilb = find_new_ilb(cpu);
-
-                        if (ilb < nr_cpu_ids)
-                                resched_cpu(ilb);
-                }
-        }
-
-        /*
-         * If this cpu is idle and doing idle load balancing for all the
-         * cpus with ticks stopped, is it time for that to stop?
-         */
-        if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu &&
-            cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
-                resched_cpu(cpu);
-                return;
-        }
-
-        /*
-         * If this cpu is idle and the idle load balancing is done by
-         * someone else, then no need raise the SCHED_SOFTIRQ
-         */
-        if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu &&
-            cpumask_test_cpu(cpu, nohz.cpu_mask))
-                return;
-#endif
-        /* 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);
-}
-
-#else   /* CONFIG_SMP */
-
-/*
- * on UP we do not need to balance between CPUs:
- */
-static inline void idle_balance(int cpu, struct rq *rq)
-{
-}
-
 #endif
 
 DEFINE_PER_CPU(struct kernel_stat, kstat);