From: Yan, Zheng Date: Wed, 5 Nov 2014 02:56:04 +0000 (-0500) Subject: perf/x86/intel: Track number of events that use the LBR callstack X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=63f0c1d84196b712fe9de99a8514486ab416d517;p=deliverable%2Flinux.git perf/x86/intel: Track number of events that use the LBR callstack 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 Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Linus Torvalds Cc: Paul Mackerras Cc: eranian@google.com Cc: jolsa@redhat.com Link: http://lkml.kernel.org/r/1415156173-10035-9-git-send-email-kan.liang@intel.com Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index ac8279e560a1..ac8e54200934 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -205,9 +205,15 @@ 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 = this_cpu_ptr(&cpu_hw_events); + struct x86_perf_task_context *task_ctx; if (!x86_pmu.lbr_nr) return; @@ -222,6 +228,12 @@ void intel_pmu_lbr_enable(struct perf_event *event) } cpuc->br_sel = event->hw.branch_reg.reg; + if (branch_user_callstack(cpuc->br_sel) && event->ctx && + event->ctx->task_ctx_data) { + task_ctx = event->ctx->task_ctx_data; + task_ctx->lbr_callstack_users++; + } + cpuc->lbr_users++; perf_sched_cb_inc(event->ctx->pmu); } @@ -229,10 +241,17 @@ void intel_pmu_lbr_enable(struct perf_event *event) void intel_pmu_lbr_disable(struct perf_event *event) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); + struct x86_perf_task_context *task_ctx; if (!x86_pmu.lbr_nr) return; + if (branch_user_callstack(cpuc->br_sel) && event->ctx && + event->ctx->task_ctx_data) { + task_ctx = event->ctx->task_ctx_data; + task_ctx->lbr_callstack_users--; + } + cpuc->lbr_users--; WARN_ON_ONCE(cpuc->lbr_users < 0); perf_sched_cb_dec(event->ctx->pmu);