From: "tip-bot for eranian@google.com" <eranian@google.com>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, eranian@google.com, hpa@zytor.com,
mingo@redhat.com, a.p.zijlstra@chello.nl, tglx@linutronix.de,
mingo@elte.hu
Subject: [tip:perf/core] perf_events: Improve task_sched_in()
Date: Thu, 11 Mar 2010 14:42:23 GMT [thread overview]
Message-ID: <tip-9b33fa6ba0e2f90fdf407501db801c2511121564@git.kernel.org> (raw)
In-Reply-To: <1268288765-5326-1-git-send-email-eranian@google.com>
Commit-ID: 9b33fa6ba0e2f90fdf407501db801c2511121564
Gitweb: http://git.kernel.org/tip/9b33fa6ba0e2f90fdf407501db801c2511121564
Author: eranian@google.com <eranian@google.com>
AuthorDate: Wed, 10 Mar 2010 22:26:05 -0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 11 Mar 2010 15:23:28 +0100
perf_events: Improve task_sched_in()
This patch is an optimization in perf_event_task_sched_in() to avoid
scheduling the events twice in a row.
Without it, the perf_disable()/perf_enable() pair is invoked twice,
thereby pinned events counts while scheduling flexible events and we go
throuh hw_perf_enable() twice.
By encapsulating, the whole sequence into perf_disable()/perf_enable() we
ensure, hw_perf_enable() is going to be invoked only once because of the
refcount protection.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268288765-5326-1-git-send-email-eranian@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/perf_event.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 52c69a3..3853d49 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -1368,6 +1368,8 @@ void perf_event_task_sched_in(struct task_struct *task)
if (cpuctx->task_ctx == ctx)
return;
+ perf_disable();
+
/*
* We want to keep the following priority order:
* cpu pinned (that don't need to move), task pinned,
@@ -1380,6 +1382,8 @@ void perf_event_task_sched_in(struct task_struct *task)
ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE);
cpuctx->task_ctx = ctx;
+
+ perf_enable();
}
#define MAX_INTERRUPTS (~0ULL)
prev parent reply other threads:[~2010-03-11 14:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-11 6:26 [PATCH] perf_events: improve task_sched_in() eranian
2010-03-11 8:35 ` Peter Zijlstra
2010-03-11 14:42 ` tip-bot for eranian@google.com [this message]
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