From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 15 Oct 2007 15:00:20 +0000 (+0200)
Subject: sched: sync wakeups preempt too
X-Git-Tag: v2.6.24-rc1~1289^2
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9c63d9c021f375a2708ad79043d6f4dd1291a085;p=linux-2.6

sched: sync wakeups preempt too

make sure sync wakeups preempt too - the scheduler will not
overschedule as we've got various throttles against that.
As a result, sync wakeups can be used more widely in the kernel
(to signal wakeup affinity between tasks), and no arbitrary
latencies will be introduced either.

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

diff --git a/kernel/sched.c b/kernel/sched.c
index 7fd3434625..bba57adb95 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1596,16 +1596,7 @@ out_activate:
 		schedstat_inc(p, se.nr_wakeups_remote);
 	update_rq_clock(rq);
 	activate_task(rq, p, 1);
-	/*
-	 * Sync wakeups (i.e. those types of wakeups where the waker
-	 * has indicated that it will leave the CPU in short order)
-	 * don't trigger a preemption, if the woken up task will run on
-	 * this cpu. (in this case the 'I will reschedule' promise of
-	 * the waker guarantees that the freshly woken up task is going
-	 * to be considered on this CPU.)
-	 */
-	if (!sync || rq->curr == rq->idle)
-		check_preempt_curr(rq, p);
+	check_preempt_curr(rq, p);
 	success = 1;
 
 out_running: