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SubjectRe: [PATCH 1/2] pebs, x86: Make sure to really disable PEBS
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On Sat, 2012-08-18 at 09:15 -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> When disabling a PEBS event we need to check the old value
> to determine if PEBS was running. Otherwise the last PEBS value
> could be kept running.
>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
> arch/x86/kernel/cpu/perf_event_intel_ds.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
> index e38d97b..db49ab3 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
> @@ -438,9 +438,10 @@ void intel_pmu_pebs_disable(struct perf_event *event)
> {
> struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
> struct hw_perf_event *hwc = &event->hw;
> + u64 old = cpuc->pebs_enabled;
>
> cpuc->pebs_enabled &= ~(1ULL << hwc->idx);
> - if (cpuc->enabled)
> + if (old)

cpuc->enabled != cpuc->pebs_enabled

> wrmsrl(MSR_IA32_PEBS_ENABLE, cpuc->pebs_enabled);
>
> hwc->config |= ARCH_PERFMON_EVENTSEL_INT;



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