From: Mike Galbraith <efault@gmx.de>
Date: Mon, 15 Oct 2007 15:00:07 +0000 (+0200)
Subject: sched: fix SMP migration latencies
X-Git-Tag: v2.6.24-rc1~1289^2~103
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=119fe5e06800afc197781ebc8c2d8ca7d03497c8;p=linux-2.6

sched: fix SMP migration latencies

fix SMP migration latencies: the vruntimes of different CPUs are
at incompatible offsets so they have to be fixed up when migrating
a task across CPUs.

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

diff --git a/kernel/sched.c b/kernel/sched.c
index 0f0cf374c7..4ad789d268 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -992,6 +992,9 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 	if (p->se.block_start)
 		p->se.block_start -= clock_offset;
 #endif
+	if (likely(new_rq->cfs.min_vruntime))
+		p->se.vruntime -= old_rq->cfs.min_vruntime -
+						new_rq->cfs.min_vruntime;
 
 	__set_task_cpu(p, new_cpu);
 }