linux-kernel - [PATCH 3.12 013/111] ARM: perf: hook up perf_sample_event

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Message-Id: <22259d1fa4111413d7969bae6ad425fbc7fcf3e1.1403512281.git.jslaby@suse.cz>
Date:	Mon, 23 Jun 2014 10:30:48 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Will Deacon <will.deacon@....com>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 013/111] ARM: perf: hook up perf_sample_event_took around pmu irq handling

From: Will Deacon <will.deacon@....com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 5f5092e72cc25a6a5785308270e0085b2b2772cc upstream.

Since we indirect all of our PMU IRQ handling through a dispatcher, it's
trivial to hook up perf_sample_event_took to prevent applications such
as oprofile from generating interrupt storms due to an unrealisticly
low sample period.

Reported-by: Robert Richter <rric@...nel.org>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 arch/arm/kernel/perf_event.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index e186ee1e63f6..de5cd767e4df 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -303,11 +303,18 @@ static irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
 	struct arm_pmu *armpmu = (struct arm_pmu *) dev;
 	struct platform_device *plat_device = armpmu->plat_device;
 	struct arm_pmu_platdata *plat = dev_get_platdata(&plat_device->dev);
+	int ret;
+	u64 start_clock, finish_clock;
 
+	start_clock = sched_clock();
 	if (plat && plat->handle_irq)
-		return plat->handle_irq(irq, dev, armpmu->handle_irq);
+		ret = plat->handle_irq(irq, dev, armpmu->handle_irq);
 	else
-		return armpmu->handle_irq(irq, dev);
+		ret = armpmu->handle_irq(irq, dev);
+	finish_clock = sched_clock();
+
+	perf_sample_event_took(finish_clock - start_clock);
+	return ret;
 }
 
 static void
-- 
2.0.0

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