sched: clean up new task placement

clean up new task placement.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>

1 files changed, 42 insertions, 15 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index a60b1dac598..cc447fbff51 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -199,6 +199,21 @@ static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
         return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node);
 }
 
+static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
+{
+        struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
+        struct sched_entity *se = NULL;
+        struct rb_node *parent;
+
+        while (*link) {
+                parent = *link;
+                se = rb_entry(parent, struct sched_entity, run_node);
+                link = &parent->rb_right;
+        }
+
+        return se;
+}
+
 /**************************************************************
  * Scheduling class statistics methods:
  */
@@ -530,6 +545,31 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
 }
 
 static void
+place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
+{
+        struct sched_entity *last = __pick_last_entity(cfs_rq);
+        u64 min_runtime, latency;
+
+        min_runtime = cfs_rq->min_vruntime;
+        if (last) {
+                min_runtime += last->vruntime;
+                min_runtime >>= 1;
+                if (initial && sched_feat(START_DEBIT))
+                        min_runtime += sysctl_sched_latency/2;
+        }
+
+        if (!initial && sched_feat(NEW_FAIR_SLEEPERS)) {
+                latency = sysctl_sched_latency;
+                if (min_runtime > latency)
+                        min_runtime -= latency;
+                else
+                        min_runtime = 0;
+        }
+
+        se->vruntime = max(se->vruntime, min_runtime);
+}
+
+static void
 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
 {
         /*
@@ -538,19 +578,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
         update_curr(cfs_rq);
 
         if (wakeup) {
-                u64 min_runtime, latency;
-
-                min_runtime = cfs_rq->min_vruntime;
-                min_runtime += sysctl_sched_latency/2;
-
-                if (sched_feat(NEW_FAIR_SLEEPERS)) {
-                        latency = calc_weighted(sysctl_sched_latency, se);
-                        if (min_runtime > latency)
-                                min_runtime -= latency;
-                }
-
-                se->vruntime = max(se->vruntime, min_runtime);
-
+                place_entity(cfs_rq, se, 0);
                 enqueue_sleeper(cfs_rq, se);
         }
 
@@ -1033,8 +1061,7 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
         sched_info_queued(p);
 
         update_curr(cfs_rq);
-        se->vruntime = cfs_rq->min_vruntime;
-        update_stats_enqueue(cfs_rq, se);
+        place_entity(cfs_rq, se, 1);
 
         /*
          * The first wait is dominated by the child-runs-first logic,