linux-kernel - [tip:sched/core] Revert "sched, x86: Optimize branch hint in __switch

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Message-ID: <tip-be8147e68625a1adb111acfd6b98a492be4b74d0@git.kernel.org>
Date:	Wed, 2 Dec 2009 13:27:36 GMT
From:	tip-bot for Tim Blechmann <tim@...ngt.org>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	tglx@...utronix.de, tim@...ngt.org, mingo@...e.hu
Subject: [tip:sched/core] Revert "sched, x86: Optimize branch hint in __switch_to()"

Commit-ID:  be8147e68625a1adb111acfd6b98a492be4b74d0
Gitweb:     http://git.kernel.org/tip/be8147e68625a1adb111acfd6b98a492be4b74d0
Author:     Tim Blechmann <tim@...ngt.org>
AuthorDate: Wed, 2 Dec 2009 12:32:10 +0100
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Wed, 2 Dec 2009 12:38:03 +0100

Revert "sched, x86: Optimize branch hint in __switch_to()"

This reverts commit a3a1de0c34de6f5f8332cd6151c46af7813c0fcb.

Commit 8ec6993d9f7d961014af970ded57542961fe9ad9 cleared the es
and ds selectors, so the original branch hints are correct now.
Therefore the branch hint doesn't need to be removed.

Signed-off-by: Tim Blechmann <tim@...ngt.org>
LKML-Reference: <4B16503A.8030508@...ngt.org>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/x86/kernel/process_64.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 93c501d..eb62cbc 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -406,10 +406,11 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	 * This won't pick up thread selector changes, but I guess that is ok.
 	 */
 	savesegment(es, prev->es);
-	if (next->es | prev->es)
+	if (unlikely(next->es | prev->es))
 		loadsegment(es, next->es);
+
 	savesegment(ds, prev->ds);
-	if (next->ds | prev->ds)
+	if (unlikely(next->ds | prev->ds))
 		loadsegment(ds, next->ds);
 
 
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