From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Tue, 16 Dec 2008 07:45:31 +0000 (+0100)
Subject: sched: optimize update_curr()
X-Git-Tag: firefly_0821_release~16485^2~5
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=34f28ecd0f4bdc733c681294d02d9fab5880591b;p=firefly-linux-kernel-4.4.55.git

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>
---

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;