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From: Tim Blechmann <tim@klingt.org>
To: linux-kernel@vger.kernel.org, x86@kernel.org
Subject: [PATCH] sched, x86: Optimize branch hint in __switch_to()
Date: Sun, 29 Nov 2009 12:55:16 +0100	[thread overview]
Message-ID: <4B126124.60902@klingt.org> (raw)


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Branch hint profiling on my nehalem machine showed 89%
incorrect branch hints:

31032542 270070841  89 __switch_to                    process_64.c         440

Signed-off-by: Tim Blechmann <tim@klingt.org>
---
 arch/x86/kernel/process_64.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)



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diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index c8d0ece..88068b3 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -437,7 +437,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	 * reload when it has changed.  When prev process used 64bit
 	 * base always reload to avoid an information leak.
 	 */
-	if (unlikely(fsindex | next->fsindex | prev->fs)) {
+	if (fsindex | next->fsindex | prev->fs) {
 		loadsegment(fs, next->fsindex);
 		/*
 		 * Check if the user used a selector != 0; if yes


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                 reply	other threads:[~2009-11-29 11:55 UTC|newest]

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