linux-kernel - [tip:perf/urgent] perf: Optimize perf

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Message-ID: <tip-32975a4f114be52286f9a5bf6c230dbb8c0e1903@git.kernel.org>
Date:	Wed, 10 Mar 2010 13:10:20 GMT
From:	tip-bot for Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	acme@...radead.org, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
	mingo@...e.hu
Subject: [tip:perf/urgent] perf: Optimize perf_disable

Commit-ID:  32975a4f114be52286f9a5bf6c230dbb8c0e1903
Gitweb:     http://git.kernel.org/tip/32975a4f114be52286f9a5bf6c230dbb8c0e1903
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Sat, 6 Mar 2010 19:49:19 +0100
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Wed, 10 Mar 2010 13:22:25 +0100

perf: Optimize perf_disable

Currently we always call hw_perf_disable(), even if its already disabled,
this seems superflous, esp. since it cannot be made NMI safe (see further
patches).

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: paulus@...ba.org
Cc: eranian@...gle.com
Cc: robert.richter@....com
Cc: fweisbec@...il.com
Cc: Arnaldo Carvalho de Melo <acme@...radead.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 kernel/perf_event.c |   16 +++-------------
 1 files changed, 3 insertions(+), 13 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 73329de..d810846 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -93,25 +93,15 @@ void __weak perf_event_print_debug(void)	{ }
 
 static DEFINE_PER_CPU(int, perf_disable_count);
 
-void __perf_disable(void)
-{
-	__get_cpu_var(perf_disable_count)++;
-}
-
-bool __perf_enable(void)
-{
-	return !--__get_cpu_var(perf_disable_count);
-}
-
 void perf_disable(void)
 {
-	__perf_disable();
-	hw_perf_disable();
+	if (!__get_cpu_var(perf_disable_count)++)
+		hw_perf_disable();
 }
 
 void perf_enable(void)
 {
-	if (__perf_enable())
+	if (!--__get_cpu_var(perf_disable_count))
 		hw_perf_enable();
 }
 
--
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