sched: optimize update_curr()

Impact: micro-optimization

Skip the hard work when there is none.

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

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 928cd74cff0d..5ad4440f0fc4 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -492,6 +492,8 @@ static void update_curr(struct cfs_rq *cfs_rq)
          * overflow on 32 bits):
          */
         delta_exec = (unsigned long)(now - curr->exec_start);
+        if (!delta_exec)
+                return;
 
         __update_curr(cfs_rq, curr, delta_exec);
         curr->exec_start = now;