4 files changed, 50 insertions, 17 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 11d8e9a74eff..3625fcaf5d0f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -929,6 +929,9 @@ struct sched_entity {
         u64                     vruntime;
         u64                     prev_sum_exec_runtime;
 
+        u64                     last_wakeup;
+        u64                     avg_overlap;
+
 #ifdef CONFIG_SCHEDSTATS
         u64                     wait_start;
         u64                     wait_max;
diff --git a/kernel/sched.c b/kernel/sched.c
index d1ad69b270ca..adbd475cfd25 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1855,10 +1855,11 @@ out_activate:
                 schedstat_inc(p, se.nr_wakeups_remote);
         update_rq_clock(rq);
         activate_task(rq, p, 1);
-        check_preempt_curr(rq, p);
         success = 1;
 
 out_running:
+        check_preempt_curr(rq, p);
+
         p->state = TASK_RUNNING;
 #ifdef CONFIG_SMP
         if (p->sched_class->task_wake_up)
@@ -1892,6 +1893,8 @@ static void __sched_fork(struct task_struct *p)
         p->se.exec_start                = 0;
         p->se.sum_exec_runtime          = 0;
         p->se.prev_sum_exec_runtime     = 0;
+        p->se.last_wakeup               = 0;
+        p->se.avg_overlap               = 0;
 
 #ifdef CONFIG_SCHEDSTATS
         p->se.wait_start                = 0;
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index 4b5e24cf2f4a..ef358ba07683 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -288,6 +288,7 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
         PN(se.exec_start);
         PN(se.vruntime);
         PN(se.sum_exec_runtime);
+        PN(se.avg_overlap);
 
         nr_switches = p->nvcsw + p->nivcsw;
 
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index b5a357396b49..87c9d3a2aafa 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -556,6 +556,21 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
         account_entity_enqueue(cfs_rq, se);
 }
 
+static void update_avg(u64 *avg, u64 sample)
+{
+        s64 diff = sample - *avg;
+        *avg += diff >> 3;
+}
+
+static void update_avg_stats(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+        if (!se->last_wakeup)
+                return;
+
+        update_avg(&se->avg_overlap, se->sum_exec_runtime - se->last_wakeup);
+        se->last_wakeup = 0;
+}
+
 static void
 dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
 {
@@ -566,6 +581,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
 
         update_stats_dequeue(cfs_rq, se);
         if (sleep) {
+                update_avg_stats(cfs_rq, se);
 #ifdef CONFIG_SCHEDSTATS
                 if (entity_is_task(se)) {
                         struct task_struct *tsk = task_of(se);
@@ -981,12 +997,15 @@ static inline int wake_idle(int cpu, struct task_struct *p)
 
 #ifdef CONFIG_SMP
 
+static const struct sched_class fair_sched_class;
+
 static int
-wake_affine(struct rq *rq, struct sched_domain *this_sd, struct task_struct *p,
-            int prev_cpu, int this_cpu, int sync, int idx,
-            unsigned long load, unsigned long this_load,
+wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
+            struct task_struct *p, int prev_cpu, int this_cpu, int sync,
+            int idx, unsigned long load, unsigned long this_load,
             unsigned int imbalance)
 {
+        struct task_struct *curr = this_rq->curr;
         unsigned long tl = this_load;
         unsigned long tl_per_task;
 
@@ -994,10 +1013,15 @@ wake_affine(struct rq *rq, struct sched_domain *this_sd, struct task_struct *p,
                 return 0;
 
         /*
-         * Attract cache-cold tasks on sync wakeups:
+         * If the currently running task will sleep within
+         * a reasonable amount of time then attract this newly
+         * woken task:
          */
-        if (sync && !task_hot(p, rq->clock, this_sd))
-                return 1;
+        if (sync && curr->sched_class == &fair_sched_class) {
+                if (curr->se.avg_overlap < sysctl_sched_migration_cost &&
+                                p->se.avg_overlap < sysctl_sched_migration_cost)
+                        return 1;
+        }
 
         schedstat_inc(p, se.nr_wakeups_affine_attempts);
         tl_per_task = cpu_avg_load_per_task(this_cpu);
@@ -1030,18 +1054,16 @@ static int select_task_rq_fair(struct task_struct *p, int sync)
         struct sched_domain *sd, *this_sd = NULL;
         int prev_cpu, this_cpu, new_cpu;
         unsigned long load, this_load;
+        struct rq *rq, *this_rq;
         unsigned int imbalance;
-        struct rq *rq;
         int idx;
 
         prev_cpu        = task_cpu(p);
         rq              = task_rq(p);
         this_cpu        = smp_processor_id();
+        this_rq         = cpu_rq(this_cpu);
         new_cpu         = prev_cpu;
 
-        if (prev_cpu == this_cpu)
-                goto out;
-
         /*
          * 'this_sd' is the first domain that both
          * this_cpu and prev_cpu are present in:
@@ -1069,11 +1091,12 @@ static int select_task_rq_fair(struct task_struct *p, int sync)
         load = source_load(prev_cpu, idx);
         this_load = target_load(this_cpu, idx);
 
-        if (wake_affine(rq, this_sd, p, prev_cpu, this_cpu, sync, idx,
-                                     load, this_load, imbalance)) {
-                new_cpu = this_cpu;
+        if (wake_affine(rq, this_sd, this_rq, p, prev_cpu, this_cpu, sync, idx,
+                                     load, this_load, imbalance))
+                return this_cpu;
+
+        if (prev_cpu == this_cpu)
                 goto out;
-        }
 
         /*
          * Start passive balancing when half the imbalance_pct
@@ -1083,8 +1106,7 @@ static int select_task_rq_fair(struct task_struct *p, int sync)
                 if (imbalance*this_load <= 100*load) {
                         schedstat_inc(this_sd, ttwu_move_balance);
                         schedstat_inc(p, se.nr_wakeups_passive);
-                        new_cpu = this_cpu;
-                        goto out;
+                        return this_cpu;
                 }
         }
 
@@ -1111,6 +1133,10 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
                 return;
         }
 
+        se->last_wakeup = se->sum_exec_runtime;
+        if (unlikely(se == pse))
+                return;
+
         cfs_rq_of(pse)->next = pse;
 
         /*