From fc631c82e1734d718ff0832558f64c8f5d185f26 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Wed, 11 Feb 2009 14:27:17 +0100
Subject: sched: revert recent sync wakeup changes

Intel reported a 10% regression (mysql+sysbench) on a 16-way machine
with these patches:

  1596e29: sched: symmetric sync vs avg_overlap
  d942fb6: sched: fix sync wakeups

Revert them.

Reported-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Bisected-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/sched_fair.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

(limited to 'kernel/sched_fair.c')

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index a7e50ba185a..0566f2a03c4 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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