please ignore this patch
On 07/07/2014 02:28 PM, Yan, Zheng wrote:
> When enabling/disabling an event, check if the event uses the LBR
> callstack feature, adjust the LBR callstack usage count accordingly.
> Later patch will use the usage count to decide if LBR stack should
> be saved/restored.
>
> Signed-off-by: Yan, Zheng <zheng.z....@intel.com>
> ---
> arch/x86/kernel/cpu/perf_event_intel_lbr.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
> b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
> index 9a94fff..66969cb 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
> @@ -198,9 +198,15 @@ void intel_pmu_lbr_sched_task(struct perf_event_context
> *ctx, bool sched_in)
> }
> }
>
> +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++;
> +
> cpuc->lbr_users++;
> if (cpuc->lbr_users == 1)
> perf_sched_cb_enable(event->ctx->pmu);
> @@ -222,10 +232,15 @@ void intel_pmu_lbr_enable(struct perf_event *event)
> void intel_pmu_lbr_disable(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;
>
> + task_ctx = event->ctx ? event->ctx->task_ctx_data : NULL;
> + if (branch_user_callstack(cpuc->br_sel))
> + task_ctx->lbr_callstack_users--;
> +
> cpuc->lbr_users--;
> WARN_ON_ONCE(cpuc->lbr_users < 0);
>
>
--
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