linux-kernel - [git pull] scheduler fixes

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Message-ID: <20090211144135.GA7088@elte.hu>
Date:	Wed, 11 Feb 2009 15:41:35 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: [git pull] scheduler fixes

Linus,

Please pull the latest sched-fixes-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git sched-fixes-for-linus

 Thanks,

	Ingo

------------------>
Peter Zijlstra (1):
      sched: revert recent sync wakeup changes

Suresh Siddha (1):
      sched: fix nohz load balancer on cpu offline


 kernel/sched.c      |   27 +++++++++++----------------
 kernel/sched_fair.c |   11 +++++++++--
 2 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 242d0d4..f11c02b 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2266,16 +2266,6 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
 	if (!sched_feat(SYNC_WAKEUPS))
 		sync = 0;
 
-	if (!sync) {
-		if (current->se.avg_overlap < sysctl_sched_migration_cost &&
-			  p->se.avg_overlap < sysctl_sched_migration_cost)
-			sync = 1;
-	} else {
-		if (current->se.avg_overlap >= sysctl_sched_migration_cost ||
-			  p->se.avg_overlap >= sysctl_sched_migration_cost)
-			sync = 0;
-	}
-
 #ifdef CONFIG_SMP
 	if (sched_feat(LB_WAKEUP_UPDATE)) {
 		struct sched_domain *sd;
@@ -3890,19 +3880,24 @@ int select_nohz_load_balancer(int stop_tick)
 	int cpu = smp_processor_id();
 
 	if (stop_tick) {
-		cpumask_set_cpu(cpu, nohz.cpu_mask);
 		cpu_rq(cpu)->in_nohz_recently = 1;
 
-		/*
-		 * If we are going offline and still the leader, give up!
-		 */
-		if (!cpu_active(cpu) &&
-		    atomic_read(&nohz.load_balancer) == cpu) {
+		if (!cpu_active(cpu)) {
+			if (atomic_read(&nohz.load_balancer) != cpu)
+				return 0;
+
+			/*
+			 * If we are going offline and still the leader,
+			 * give up!
+			 */
 			if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
 				BUG();
+
 			return 0;
 		}
 
+		cpumask_set_cpu(cpu, nohz.cpu_mask);
+
 		/* time for ilb owner also to sleep */
 		if (cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
 			if (atomic_read(&nohz.load_balancer) == cpu)
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index a7e50ba..0566f2a 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1191,15 +1191,20 @@ wake_affine(struct sched_domain *this_sd, struct rq *this_rq,
 	    int idx, unsigned long load, unsigned long this_load,
 	    unsigned int imbalance)
 {
+	struct task_struct *curr = this_rq->curr;
+	struct task_group *tg;
 	unsigned long tl = this_load;
 	unsigned long tl_per_task;
-	struct task_group *tg;
 	unsigned long weight;
 	int balanced;
 
 	if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS))
 		return 0;
 
+	if (sync && (curr->se.avg_overlap > sysctl_sched_migration_cost ||
+			p->se.avg_overlap > sysctl_sched_migration_cost))
+		sync = 0;
+
 	/*
 	 * If sync wakeup then subtract the (maximum possible)
 	 * effect of the currently running task from the load
@@ -1426,7 +1431,9 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
 	if (!sched_feat(WAKEUP_PREEMPT))
 		return;
 
-	if (sched_feat(WAKEUP_OVERLAP) && sync) {
+	if (sched_feat(WAKEUP_OVERLAP) && (sync ||
+			(se->avg_overlap < sysctl_sched_migration_cost &&
+			 pse->avg_overlap < sysctl_sched_migration_cost))) {
 		resched_task(curr);
 		return;
 	}
--
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