linux-kernel - [tip:perf/core] perf_events, x86: Remove spurious counter reset from x86_pmu

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Message-ID: <tip-18c01f8abff51e4910cc5ffb4b710e8c6eea60c9@git.kernel.org>
Date:	Fri, 29 Jan 2010 09:30:41 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, eranian@...gle.com, hpa@...or.com,
	mingo@...hat.com, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
	mingo@...e.hu
Subject: [tip:perf/core] perf_events, x86: Remove spurious counter reset from x86_pmu_enable()

Commit-ID:  18c01f8abff51e4910cc5ffb4b710e8c6eea60c9
Gitweb:     http://git.kernel.org/tip/18c01f8abff51e4910cc5ffb4b710e8c6eea60c9
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Wed, 27 Jan 2010 23:07:49 +0100
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 29 Jan 2010 09:01:49 +0100

perf_events, x86: Remove spurious counter reset from x86_pmu_enable()

At enable time the counter might still have a ->idx pointing to
a previously occupied location that might now be taken by
another event. Resetting the counter at that location with data
from this event will destroy the other counter's count.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Stephane Eranian <eranian@...gle.com>
LKML-Reference: <20100127221122.261477183@...llo.nl>
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 3fac0bf..518eb3e 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1762,9 +1762,6 @@ static int x86_pmu_enable(struct perf_event *event)
 	cpuc->n_events = n;
 	cpuc->n_added  = n - n0;
 
-	if (hwc->idx != -1)
-		x86_perf_event_set_period(event, hwc, hwc->idx);
-
 	return 0;
 }
 
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