linux-kernel - [GIT PULL, v2] scheduler fixes

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Date:	Fri, 23 Oct 2009 16:46:48 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Mike Galbraith <efault@....de>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL, v2] scheduler fixes


* Ingo Molnar <mingo@...e.hu> wrote:

> 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

Sorry - the tail commit was bad and i forgot to exclude it. Updated pull 
request (with different URI):

Please pull the latest sched-fixes-for-linus-2 git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git sched-fixes-for-linus-2

 Thanks,

	Ingo

------------------>
Peter Zijlstra (2):
      sched: Disable SD_PREFER_LOCAL for MC/CPU domains
      sched: Do less agressive buddy clearing


 arch/x86/include/asm/topology.h |    1 +
 include/linux/topology.h        |    4 ++--
 kernel/sched_fair.c             |   27 +++++++++++++--------------
 3 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index 25a9284..d823c24 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -143,6 +143,7 @@ extern unsigned long node_remap_size[];
 				| 1*SD_BALANCE_FORK			\
 				| 0*SD_BALANCE_WAKE			\
 				| 1*SD_WAKE_AFFINE			\
+				| 1*SD_PREFER_LOCAL			\
 				| 0*SD_SHARE_CPUPOWER			\
 				| 0*SD_POWERSAVINGS_BALANCE		\
 				| 0*SD_SHARE_PKG_RESOURCES		\
diff --git a/include/linux/topology.h b/include/linux/topology.h
index fc0bf3e..57e6357 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -129,7 +129,7 @@ int arch_update_cpu_topology(void);
 				| 1*SD_BALANCE_FORK			\
 				| 0*SD_BALANCE_WAKE			\
 				| 1*SD_WAKE_AFFINE			\
-				| 1*SD_PREFER_LOCAL			\
+				| 0*SD_PREFER_LOCAL			\
 				| 0*SD_SHARE_CPUPOWER			\
 				| 1*SD_SHARE_PKG_RESOURCES		\
 				| 0*SD_SERIALIZE			\
@@ -162,7 +162,7 @@ int arch_update_cpu_topology(void);
 				| 1*SD_BALANCE_FORK			\
 				| 0*SD_BALANCE_WAKE			\
 				| 1*SD_WAKE_AFFINE			\
-				| 1*SD_PREFER_LOCAL			\
+				| 0*SD_PREFER_LOCAL			\
 				| 0*SD_SHARE_CPUPOWER			\
 				| 0*SD_SHARE_PKG_RESOURCES		\
 				| 0*SD_SERIALIZE			\
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 4e777b4..c32c3e6 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -861,12 +861,21 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
 {
 	struct sched_entity *se = __pick_next_entity(cfs_rq);
+	struct sched_entity *buddy;
 
-	if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, se) < 1)
-		return cfs_rq->next;
+	if (cfs_rq->next) {
+		buddy = cfs_rq->next;
+		cfs_rq->next = NULL;
+		if (wakeup_preempt_entity(buddy, se) < 1)
+			return buddy;
+	}
 
-	if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, se) < 1)
-		return cfs_rq->last;
+	if (cfs_rq->last) {
+		buddy = cfs_rq->last;
+		cfs_rq->last = NULL;
+		if (wakeup_preempt_entity(buddy, se) < 1)
+			return buddy;
+	}
 
 	return se;
 }
@@ -1654,16 +1663,6 @@ static struct task_struct *pick_next_task_fair(struct rq *rq)
 
 	do {
 		se = pick_next_entity(cfs_rq);
-		/*
-		 * If se was a buddy, clear it so that it will have to earn
-		 * the favour again.
-		 *
-		 * If se was not a buddy, clear the buddies because neither
-		 * was elegible to run, let them earn it again.
-		 *
-		 * IOW. unconditionally clear buddies.
-		 */
-		__clear_buddies(cfs_rq, NULL);
 		set_next_entity(cfs_rq, se);
 		cfs_rq = group_cfs_rq(se);
 	} while (cfs_rq);
--
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