diff options
| author | Will Deacon <will.deacon@arm.com> | 2011-07-01 14:38:12 +0100 |
|---|---|---|
| committer | Andi Kleen <ak@linux.intel.com> | 2011-08-01 13:55:04 -0700 |
| commit | 64779cb190a6ba7a03b658cd0584cef74fb9c208 (patch) | |
| tree | 624050de234886de90dbfe91dab403819fca0ac9 | |
| parent | 225686544fb9af569ea70a46e11fe130c6da5bd2 (diff) | |
| download | lwn-64779cb190a6ba7a03b658cd0584cef74fb9c208.tar.gz lwn-64779cb190a6ba7a03b658cd0584cef74fb9c208.zip | |
ARM: 6989/1: perf: do not start the PMU when no events are
[ upstream commit f4f38430c94c38187db73a2cf3892cc8b12a2713 ]
present
armpmu_enable can be called in situations where no events are present
(for example, from the event rotation tick after a profiled task has
exited). In this case, we currently start the PMU anyway which may
leave it active inevitably without any events being monitored.
This patch adds a simple check to the enabling code so that we avoid
starting the PMU when no events are present.
Cc: <stable@kernel.org>
Reported-by: Ashwin Chaugle <ashwinc@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
| -rw-r--r-- | arch/arm/kernel/perf_event.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c index de12536d687f..2297594224da 100644 --- a/arch/arm/kernel/perf_event.c +++ b/arch/arm/kernel/perf_event.c @@ -531,7 +531,7 @@ void hw_perf_enable(void) { /* Enable all of the perf events on hardware. */ - int idx; + int idx, enabled = 0; struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); if (!armpmu) @@ -544,9 +544,11 @@ hw_perf_enable(void) continue; armpmu->enable(&event->hw, idx); + enabled = 1; } - armpmu->start(); + if (enabled) + armpmu->start(); } void |