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SubjectRe: [PATCH V4 07/16] perf, x86: track number of events that use LBR callstack
On Mon, Jun 30, 2014 at 04:50:44PM +0800, Yan, Zheng wrote:
> +static inline bool branch_user_callstack(unsigned br_sel)
> +{
> + return (br_sel & X86_BR_USER) && (br_sel & X86_BR_CALL_STACK);
> +}
> +
> void intel_pmu_lbr_enable(struct perf_event *event)
> {
> struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
> + struct x86_perf_task_context *task_ctx;
>
> if (!x86_pmu.lbr_nr)
> return;
> @@ -214,6 +220,10 @@ void intel_pmu_lbr_enable(struct perf_event *event)
> }
> cpuc->br_sel = event->hw.branch_reg.reg;
>
> + task_ctx = event->ctx ? event->ctx->task_ctx_data : NULL;
> + if (branch_user_callstack(cpuc->br_sel))
> + task_ctx->lbr_callstack_users++;
> +

So what happens if we make a per-cpu event which satisfies
branch_user_callstack() ?
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