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SubjectRe: [RESEND PATCH V2 3/4] perf/x86/intel: drain PEBS buffer in event read
On Mon, Jan 08, 2018 at 07:15:15AM -0800, kan.liang@intel.com wrote:
> From: Kan Liang <kan.liang@linux.intel.com>
>
> When the PEBS interrupt threshold is larger than one, there is no way to
> get exact auto-reload times and value needed for event update unless
> flush the PEBS buffer.
>
> Drain the PEBS buffer in event read when large PEBS is enabled.
>
> For the threshold is one, even auto-reload is enabled, it doesn't need
> to be specially handled. Because auto-reload is only effect when event
> overflow. There is no overflow in event read.
>
> Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
> ---
> arch/x86/events/intel/core.c | 9 +++++++++
> arch/x86/events/intel/ds.c | 10 ++++++++++
> arch/x86/events/perf_event.h | 2 ++
> 3 files changed, 21 insertions(+)
>
> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> index 09c26a4..bdc35f8 100644
> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -2060,6 +2060,14 @@ static void intel_pmu_del_event(struct perf_event *event)
> intel_pmu_pebs_del(event);
> }
>
> +static void intel_pmu_read_event(struct perf_event *event)
> +{
> + if (event->attr.precise_ip)
> + return intel_pmu_pebs_read(event);

check for (event->hw.flags & PERF_X86_EVENT_AUTO_RELOAD)
would be more accurate?

jirka

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