linux-kernel - [PATCH 2/2 -tip] perf: Don't generate events for the idle task when exclude

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Message-ID: <ye8pr8fmlq7.fsf@camel16.daimi.au.dk>
Date:	22 Oct 2009 18:34:08 +0200
From:	Soeren Sandmann <sandmann@...mi.au.dk>
To:	linux-kernel@...r.kernel.org
Cc:	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Fr??d??ric Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH 2/2 -tip] perf: Don't generate events for the idle task when exclude_idle is set.

Getting samples for the idle task is often not interesting, so don't
generate them when exclude_idle is set for the event in question.

Signed-off-by: SÃ¸ren Sandmann Pedersen <sandmann@...hat.com>
---
 kernel/perf_event.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index b492c55..7bc84cb 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -3959,8 +3959,9 @@ static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer)
 		regs = task_pt_regs(current);
 
 	if (regs) {
-		if (perf_event_overflow(event, 0, &data, regs))
-			ret = HRTIMER_NORESTART;
+		if (!(event->attr.exclude_idle && current->pid == 0))
+			if (perf_event_overflow(event, 0, &data, regs))
+				ret = HRTIMER_NORESTART;
 	}
 
 	period = max_t(u64, 10000, event->hw.sample_period);
-- 
1.6.5.rc2

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