linux-kernel - [tip:sched/urgent] sched: Disable SD_PREFER

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Message-ID: <tip-753c72119743e8a12f5e9d34312988c810458917@git.kernel.org>
Date:	Mon, 2 Nov 2009 19:45:38 GMT
From:	tip-bot for Mike Galbraith <efault@....de>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	a.p.zijlstra@...llo.nl, yanmin_zhang@...ux.intel.com,
	efault@....de, tglx@...utronix.de, mingo@...e.hu
Subject: [tip:sched/urgent] sched: Disable SD_PREFER_LOCAL at node level

Commit-ID:  753c72119743e8a12f5e9d34312988c810458917
Gitweb:     http://git.kernel.org/tip/753c72119743e8a12f5e9d34312988c810458917
Author:     Mike Galbraith <efault@....de>
AuthorDate: Mon, 2 Nov 2009 20:36:51 +0100
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Mon, 2 Nov 2009 20:43:07 +0100

sched: Disable SD_PREFER_LOCAL at node level

Yanmin Zhang reported that SD_PREFER_LOCAL induces an order of
magnitude increase in select_task_rq_fair() overhead while
running heavy wakeup benchmarks (tbench and vmark).

Since SD_BALANCE_WAKE is off at node level, turn SD_PREFER_LOCAL
off as well pending further investigation.

Reported-by: Zhang, Yanmin <yanmin_zhang@...ux.intel.com>
Signed-off-by: Mike Galbraith <efault@....de>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/x86/include/asm/topology.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index d823c24..40e37b1 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -143,7 +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_PREFER_LOCAL			\
 				| 0*SD_SHARE_CPUPOWER			\
 				| 0*SD_POWERSAVINGS_BALANCE		\
 				| 0*SD_SHARE_PKG_RESOURCES		\
--
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