sched: speed up context-switches a bit

speed up context-switches a bit by not clearing p->exec_start.

(as a side-effect, this also makes p->exec_start a universal timestamp
available to cache-hot estimations.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index c240b72b4e62b5b5be19b4efc4e7f2786d0b6822..cea1fa32b3f4f64b35fe2526e5af700547e8c2f7 100644 (file)
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -379,15 +379,6 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
        se->exec_start = rq_of(cfs_rq)->clock;
 }
 
-/*
- * We are descheduling a task - update its stats:
- */
-static inline void
-update_stats_curr_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
-       se->exec_start = 0;
-}
-
 /**************************************************
  * Scheduling class queueing methods:
  */
@@ -609,8 +600,6 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
        if (prev->on_rq)
                update_curr(cfs_rq);
 
-       update_stats_curr_end(cfs_rq, prev);
-
        check_spread(cfs_rq, prev);
        if (prev->on_rq) {
                update_stats_wait_start(cfs_rq, prev);