[PATCH 3.10 39/40] ARM: perf: hook up perf_sample_event_took around pmu irq handling

Greg Kroah-Hartman
2014-06-09T22:49:10Z

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

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@kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Weng Meiling <wengmeiling.weng@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/arm/kernel/perf_event.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -303,11 +303,18 @@ static irqreturn_t armpmu_dispatch_irq(i
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