linux-kernel - [tip:perf/core] perf: Optimize ctx_sched

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Message-ID: <tip-075e0b00857e166dcc3e39037a1fc5a90acac709@git.kernel.org>
Date:	Sat, 28 May 2011 16:38:28 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,
	a.p.zijlstra@...llo.nl, oleg@...hat.com, tglx@...utronix.de,
	mingo@...e.hu
Subject: [tip:perf/core] perf: Optimize ctx_sched_out()

Commit-ID:  075e0b00857e166dcc3e39037a1fc5a90acac709
Gitweb:     http://git.kernel.org/tip/075e0b00857e166dcc3e39037a1fc5a90acac709
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Sat, 9 Apr 2011 21:17:40 +0200
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Sat, 28 May 2011 18:01:09 +0200

perf: Optimize ctx_sched_out()

Oleg noted that ctx_sched_out() disables the PMU even though it might
not actually do something, avoid needless PMU-disabling.

Reported-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/r/20110409192141.665385503@chello.nl
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 kernel/events/core.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index d863b3c..4d9a1f01 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1760,7 +1760,6 @@ static void ctx_sched_out(struct perf_event_context *ctx,
 	struct perf_event *event;
 
 	raw_spin_lock(&ctx->lock);
-	perf_pmu_disable(ctx->pmu);
 	ctx->is_active = 0;
 	if (likely(!ctx->nr_events))
 		goto out;
@@ -1770,6 +1769,7 @@ static void ctx_sched_out(struct perf_event_context *ctx,
 	if (!ctx->nr_active)
 		goto out;
 
+	perf_pmu_disable(ctx->pmu);
 	if (event_type & EVENT_PINNED) {
 		list_for_each_entry(event, &ctx->pinned_groups, group_entry)
 			group_sched_out(event, cpuctx, ctx);
@@ -1779,8 +1779,8 @@ static void ctx_sched_out(struct perf_event_context *ctx,
 		list_for_each_entry(event, &ctx->flexible_groups, group_entry)
 			group_sched_out(event, cpuctx, ctx);
 	}
-out:
 	perf_pmu_enable(ctx->pmu);
+out:
 	raw_spin_unlock(&ctx->lock);
 }
 
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