linux-kernel - [tip:perf/core] perf_events, x86: Remove superflous MSR writes

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Message-ID: <tip-6667661df4bc76083edf1e08831c20f64429709d@git.kernel.org>
Date:	Fri, 26 Feb 2010 10:25:54 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,
	arjan@...ux.intel.com, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
	mingo@...e.hu
Subject: [tip:perf/core] perf_events, x86: Remove superflous MSR writes

Commit-ID:  6667661df4bc76083edf1e08831c20f64429709d
Gitweb:     http://git.kernel.org/tip/6667661df4bc76083edf1e08831c20f64429709d
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Wed, 10 Feb 2010 16:10:48 +0100
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 26 Feb 2010 10:56:54 +0100

perf_events, x86: Remove superflous MSR writes

We re-program the event control register every time we reset the count,
this appears to be superflous, hence remove it.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Arjan van de Ven <arjan@...ux.intel.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/x86/kernel/cpu/perf_event.c |    3 ---
 1 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index ad09656..dd09ccc 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -2009,9 +2009,6 @@ static int intel_pmu_save_and_restart(struct perf_event *event)
 	x86_perf_event_update(event, hwc, idx);
 	ret = x86_perf_event_set_period(event, hwc, idx);
 
-	if (event->state == PERF_EVENT_STATE_ACTIVE)
-		intel_pmu_enable_event(hwc, idx);
-
 	return ret;
 }
 
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