From a46a23000198d929391aa9dac8de68734efa2703 Mon Sep 17 00:00:00 2001 From: "Yan, Zheng" Date: Tue, 4 Nov 2014 21:56:06 -0500 Subject: [PATCH] perf: Simplify the branch stack check Use event->attr.branch_sample_type to replace intel_pmu_needs_lbr_smpl() for avoiding duplicated code that implicitly enables the LBR. Currently, branch stack can be enabled by user explicitly requesting branch sampling or implicit branch sampling to correct PEBS skid. For user explicitly requested branch sampling, the branch_sample_type is explicitly set by user. For PEBS case, the branch_sample_type is also implicitly set to PERF_SAMPLE_BRANCH_ANY in x86_pmu_hw_config. 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/1415156173-10035-11-git-send-email-kan.liang@intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event_intel.c | 20 +++----------------- include/linux/perf_event.h | 5 +++++ kernel/events/core.c | 3 +++ 3 files changed, 11 insertions(+), 17 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index a485ba124476..9f1dd18fa395 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -1029,20 +1029,6 @@ static __initconst const u64 slm_hw_cache_event_ids }, }; -static inline bool intel_pmu_needs_lbr_smpl(struct perf_event *event) -{ - /* user explicitly requested branch sampling */ - if (has_branch_stack(event)) - return true; - - /* implicit branch sampling to correct PEBS skid */ - if (x86_pmu.intel_cap.pebs_trap && event->attr.precise_ip > 1 && - x86_pmu.intel_cap.pebs_format < 2) - return true; - - return false; -} - static void intel_pmu_disable_all(void) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); @@ -1207,7 +1193,7 @@ static void intel_pmu_disable_event(struct perf_event *event) * must disable before any actual event * because any event may be combined with LBR */ - if (intel_pmu_needs_lbr_smpl(event)) + if (needs_branch_stack(event)) intel_pmu_lbr_disable(event); if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL)) { @@ -1268,7 +1254,7 @@ static void intel_pmu_enable_event(struct perf_event *event) * must enabled before any actual event * because any event may be combined with LBR */ - if (intel_pmu_needs_lbr_smpl(event)) + if (needs_branch_stack(event)) intel_pmu_lbr_enable(event); if (event->attr.exclude_host) @@ -1747,7 +1733,7 @@ static int intel_pmu_hw_config(struct perf_event *event) if (event->attr.precise_ip && x86_pmu.pebs_aliases) x86_pmu.pebs_aliases(event); - if (intel_pmu_needs_lbr_smpl(event)) { + if (needs_branch_stack(event)) { ret = intel_pmu_setup_lbr_filter(event); if (ret) return ret; diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 270cd0173e61..43cc158487e6 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -814,6 +814,11 @@ static inline bool has_branch_stack(struct perf_event *event) return event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK; } +static inline bool needs_branch_stack(struct perf_event *event) +{ + return event->attr.branch_sample_type != 0; +} + extern int perf_output_begin(struct perf_output_handle *handle, struct perf_event *event, unsigned int size); extern void perf_output_end(struct perf_output_handle *handle); diff --git a/kernel/events/core.c b/kernel/events/core.c index 84451c0debba..257eccf9afd4 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7232,6 +7232,9 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP)) goto err_ns; + if (!has_branch_stack(event)) + event->attr.branch_sample_type = 0; + pmu = perf_init_event(event); if (!pmu) goto err_ns;