1 files changed, 64 insertions, 222 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 716cfc8e099e..f864b751fd19 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -406,34 +406,23 @@ struct cfs_rq {
         struct task_group *tg;  /* group that "owns" this runqueue */
 
 #ifdef CONFIG_SMP
-        unsigned long task_weight;
-        unsigned long shares;
         /*
-         * We need space to build a sched_domain wide view of the full task
-         * group tree, in order to avoid depending on dynamic memory allocation
-         * during the load balancing we place this in the per cpu task group
-         * hierarchy. This limits the load balancing to one instance per cpu,
-         * but more should not be needed anyway.
+         * the part of load.weight contributed by tasks
          */
-        struct aggregate_struct {
-                /*
-                 *   load = weight(cpus) * f(tg)
-                 *
-                 * Where f(tg) is the recursive weight fraction assigned to
-                 * this group.
-                 */
-                unsigned long load;
+        unsigned long task_weight;
 
-                /*
-                 * part of the group weight distributed to this span.
-                 */
-                unsigned long shares;
+        /*
+         *   h_load = weight * f(tg)
+         *
+         * Where f(tg) is the recursive weight fraction assigned to
+         * this group.
+         */
+        unsigned long h_load;
 
-                /*
-                 * The sum of all runqueue weights within this span.
-                 */
-                unsigned long rq_weight;
-        } aggregate;
+        /*
+         * this cpu's part of tg->shares
+         */
+        unsigned long shares;
 #endif
 #endif
 };
@@ -1443,47 +1432,14 @@ static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
 
-/*
- * Group load balancing.
- *
- * We calculate a few balance domain wide aggregate numbers; load and weight.
- * Given the pictures below, and assuming each item has equal weight:
- *
- *         root          1 - thread
- *         / | \         A - group
- *        A  1  B
- *       /|\   / \
- *      C 2 D 3   4
- *      |   |
- *      5   6
- *
- * load:
- *    A and B get 1/3-rd of the total load. C and D get 1/3-rd of A's 1/3-rd,
- *    which equals 1/9-th of the total load.
- *
- * shares:
- *    The weight of this group on the selected cpus.
- *
- * rq_weight:
- *    Direct sum of all the cpu's their rq weight, e.g. A would get 3 while
- *    B would get 2.
- */
-
-static inline struct aggregate_struct *
-aggregate(struct task_group *tg, int cpu)
-{
-        return &tg->cfs_rq[cpu]->aggregate;
-}
-
-typedef void (*aggregate_func)(struct task_group *, int, struct sched_domain *);
+typedef void (*tg_visitor)(struct task_group *, int, struct sched_domain *);
 
 /*
  * Iterate the full tree, calling @down when first entering a node and @up when
  * leaving it for the final time.
  */
-static
-void aggregate_walk_tree(aggregate_func down, aggregate_func up,
-                         int cpu, struct sched_domain *sd)
+static void
+walk_tg_tree(tg_visitor down, tg_visitor up, int cpu, struct sched_domain *sd)
 {
         struct task_group *parent, *child;
 
@@ -1507,72 +1463,6 @@ up:
         rcu_read_unlock();
 }
 
-/*
- * Calculate the aggregate runqueue weight.
- */
-static void
-aggregate_group_weight(struct task_group *tg, int cpu, struct sched_domain *sd)
-{
-        unsigned long rq_weight = 0;
-        int i;
-
-        for_each_cpu_mask(i, sd->span)
-                rq_weight += tg->cfs_rq[i]->load.weight;
-
-        aggregate(tg, cpu)->rq_weight = rq_weight;
-}
-
-/*
- * Compute the weight of this group on the given cpus.
- */
-static void
-aggregate_group_shares(struct task_group *tg, int cpu, struct sched_domain *sd)
-{
-        unsigned long shares = 0;
-        int i;
-
-        for_each_cpu_mask(i, sd->span)
-                shares += tg->cfs_rq[i]->shares;
-
-        if ((!shares && aggregate(tg, cpu)->rq_weight) || shares > tg->shares)
-                shares = tg->shares;
-
-        if (!sd->parent || !(sd->parent->flags & SD_LOAD_BALANCE))
-                shares = tg->shares;
-
-        aggregate(tg, cpu)->shares = shares;
-}
-
-/*
- * Compute the load fraction assigned to this group, relies on the aggregate
- * weight and this group's parent's load, i.e. top-down.
- */
-static void
-aggregate_group_load(struct task_group *tg, int cpu, struct sched_domain *sd)
-{
-        unsigned long load;
-
-        if (!tg->parent) {
-                int i;
-
-                load = 0;
-                for_each_cpu_mask(i, sd->span)
-                        load += cpu_rq(i)->load.weight;
-
-        } else {
-                load = aggregate(tg->parent, cpu)->load;
-
-                /*
-                 * shares is our weight in the parent's rq so
-                 * shares/parent->rq_weight gives our fraction of the load
-                 */
-                load *= aggregate(tg, cpu)->shares;
-                load /= aggregate(tg->parent, cpu)->rq_weight + 1;
-        }
-
-        aggregate(tg, cpu)->load = load;
-}
-
 static void __set_se_shares(struct sched_entity *se, unsigned long shares);
 
 /*
@@ -1580,16 +1470,16 @@ static void __set_se_shares(struct sched_entity *se, unsigned long shares);
  */
 static void
 __update_group_shares_cpu(struct task_group *tg, int cpu,
-                          struct sched_domain *sd, int tcpu)
+                          unsigned long sd_shares, unsigned long sd_rq_weight)
 {
         int boost = 0;
         unsigned long shares;
         unsigned long rq_weight;
 
-        if (!tg->se[tcpu])
+        if (!tg->se[cpu])
                 return;
 
-        rq_weight = tg->cfs_rq[tcpu]->load.weight;
+        rq_weight = tg->cfs_rq[cpu]->load.weight;
 
         /*
          * If there are currently no tasks on the cpu pretend there is one of
@@ -1601,124 +1491,97 @@ __update_group_shares_cpu(struct task_group *tg, int cpu,
                 rq_weight = NICE_0_LOAD;
         }
 
+        if (unlikely(rq_weight > sd_rq_weight))
+                rq_weight = sd_rq_weight;
+
         /*
          *           \Sum shares * rq_weight
          * shares =  -----------------------
          *               \Sum rq_weight
          *
          */
-        shares = aggregate(tg, cpu)->shares * rq_weight;
-        shares /= aggregate(tg, cpu)->rq_weight + 1;
+        shares = (sd_shares * rq_weight) / (sd_rq_weight + 1);
 
         /*
          * record the actual number of shares, not the boosted amount.
          */
-        tg->cfs_rq[tcpu]->shares = boost ? 0 : shares;
+        tg->cfs_rq[cpu]->shares = boost ? 0 : shares;
 
         if (shares < MIN_SHARES)
                 shares = MIN_SHARES;
         else if (shares > MAX_SHARES)
                 shares = MAX_SHARES;
 
-        __set_se_shares(tg->se[tcpu], shares);
+        __set_se_shares(tg->se[cpu], shares);
 }
 
 /*
- * Re-adjust the weights on the cpu the task came from and on the cpu the
- * task went to.
+ * Re-compute the task group their per cpu shares over the given domain.
+ * This needs to be done in a bottom-up fashion because the rq weight of a
+ * parent group depends on the shares of its child groups.
  */
 static void
-__move_group_shares(struct task_group *tg, int cpu, struct sched_domain *sd,
-                    int scpu, int dcpu)
+tg_shares_up(struct task_group *tg, int cpu, struct sched_domain *sd)
 {
-        __update_group_shares_cpu(tg, cpu, sd, scpu);
-        __update_group_shares_cpu(tg, cpu, sd, dcpu);
-}
+        unsigned long rq_weight = 0;
+        unsigned long shares = 0;
+        int i;
 
-/*
- * Because changing a group's shares changes the weight of the super-group
- * we need to walk up the tree and change all shares until we hit the root.
- */
-static void
-move_group_shares(struct task_group *tg, int cpu, struct sched_domain *sd,
-                  int scpu, int dcpu)
-{
-        while (tg) {
-                __move_group_shares(tg, cpu, sd, scpu, dcpu);
-                tg = tg->parent;
+        for_each_cpu_mask(i, sd->span) {
+                rq_weight += tg->cfs_rq[i]->load.weight;
+                shares += tg->cfs_rq[i]->shares;
         }
-}
 
-static void
-aggregate_group_set_shares(struct task_group *tg, int cpu, struct sched_domain *sd)
-{
-        int i;
+        if ((!shares && rq_weight) || shares > tg->shares)
+                shares = tg->shares;
+
+        if (!sd->parent || !(sd->parent->flags & SD_LOAD_BALANCE))
+                shares = tg->shares;
 
         for_each_cpu_mask(i, sd->span) {
                 struct rq *rq = cpu_rq(i);
                 unsigned long flags;
 
                 spin_lock_irqsave(&rq->lock, flags);
-                __update_group_shares_cpu(tg, cpu, sd, i);
+                __update_group_shares_cpu(tg, i, shares, rq_weight);
                 spin_unlock_irqrestore(&rq->lock, flags);
         }
-
-        aggregate_group_shares(tg, cpu, sd);
 }
 
 /*
- * Calculate the accumulative weight and recursive load of each task group
- * while walking down the tree.
+ * 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 void
-aggregate_get_down(struct task_group *tg, int cpu, struct sched_domain *sd)
+tg_load_down(struct task_group *tg, int cpu, struct sched_domain *sd)
 {
-        aggregate_group_weight(tg, cpu, sd);
-        aggregate_group_shares(tg, cpu, sd);
-        aggregate_group_load(tg, cpu, sd);
-}
-
-/*
- * Rebalance the cpu shares while walking back up the tree.
- */
-static void
-aggregate_get_up(struct task_group *tg, int cpu, struct sched_domain *sd)
-{
-        aggregate_group_set_shares(tg, cpu, sd);
-}
-
-static void
-aggregate_get_nop(struct task_group *tg, int cpu, struct sched_domain *sd)
-{
-}
-
-static DEFINE_PER_CPU(spinlock_t, aggregate_lock);
+        unsigned long load;
 
-static void __init init_aggregate(void)
-{
-        int i;
+        if (!tg->parent) {
+                load = cpu_rq(cpu)->load.weight;
+        } else {
+                load = tg->parent->cfs_rq[cpu]->h_load;
+                load *= tg->cfs_rq[cpu]->shares;
+                load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
+        }
 
-        for_each_possible_cpu(i)
-                spin_lock_init(&per_cpu(aggregate_lock, i));
+        tg->cfs_rq[cpu]->h_load = load;
 }
 
-static int get_aggregate(int cpu, struct sched_domain *sd)
+static void
+tg_nop(struct task_group *tg, int cpu, struct sched_domain *sd)
 {
-        if (!spin_trylock(&per_cpu(aggregate_lock, cpu)))
-                return 0;
-
-        aggregate_walk_tree(aggregate_get_down, aggregate_get_up, cpu, sd);
-        return 1;
 }
 
-static void update_aggregate(int cpu, struct sched_domain *sd)
+static void update_shares(struct sched_domain *sd)
 {
-        aggregate_walk_tree(aggregate_get_down, aggregate_get_nop, cpu, sd);
+        walk_tg_tree(tg_nop, tg_shares_up, 0, sd);
 }
 
-static void put_aggregate(int cpu, struct sched_domain *sd)
+static void update_h_load(int cpu)
 {
-        spin_unlock(&per_cpu(aggregate_lock, cpu));
+        walk_tg_tree(tg_load_down, tg_nop, cpu, NULL);
 }
 
 static void cfs_rq_set_shares(struct cfs_rq *cfs_rq, unsigned long shares)
@@ -1728,22 +1591,10 @@ static void cfs_rq_set_shares(struct cfs_rq *cfs_rq, unsigned long shares)
 
 #else
 
-static inline void init_aggregate(void)
-{
-}
-
-static inline int get_aggregate(int cpu, struct sched_domain *sd)
-{
-        return 0;
-}
-
-static inline void update_aggregate(int cpu, struct sched_domain *sd)
+static inline void update_shares(struct sched_domain *sd)
 {
 }
 
-static inline void put_aggregate(int cpu, struct sched_domain *sd)
-{
-}
 #endif
 
 #endif
@@ -2172,12 +2023,6 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
         int load_idx = sd->forkexec_idx;
         int imbalance = 100 + (sd->imbalance_pct-100)/2;
 
-        /*
-         * now that we have both rqs locked the rq weight won't change
-         * anymore - so update the stats.
-         */
-        update_aggregate(this_cpu, sd);
-
         do {
                 unsigned long load, avg_load;
                 int local_group;
@@ -3521,12 +3366,9 @@ static int load_balance(int this_cpu, struct rq *this_rq,
         unsigned long imbalance;
         struct rq *busiest;
         unsigned long flags;
-        int unlock_aggregate;
 
         cpus_setall(*cpus);
 
-        unlock_aggregate = get_aggregate(this_cpu, sd);
-
         /*
          * When power savings policy is enabled for the parent domain, idle
          * sibling can pick up load irrespective of busy siblings. In this case,
@@ -3540,6 +3382,7 @@ static int load_balance(int this_cpu, struct rq *this_rq,
         schedstat_inc(sd, lb_count[idle]);
 
 redo:
+        update_shares(sd);
         group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
                                    cpus, balance);
 
@@ -3663,8 +3506,8 @@ out_one_pinned:
         else
                 ld_moved = 0;
 out:
-        if (unlock_aggregate)
-                put_aggregate(this_cpu, sd);
+        if (ld_moved)
+                update_shares(sd);
         return ld_moved;
 }
 
@@ -8019,7 +7862,6 @@ void __init sched_init(void)
         }
 
 #ifdef CONFIG_SMP
-        init_aggregate();
         init_defrootdomain();
 #endif