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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 <zheng.z.yan@intel.com> Signed-off-by: Kan Liang <kan.liang@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Mackerras <paulus@samba.org> 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 <mingo@kernel.org>
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parent
76cb2c617f
commit
a46a230001
3 changed files with 11 additions and 17 deletions
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@ -1029,20 +1029,6 @@ static __initconst const u64 slm_hw_cache_event_ids
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},
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};
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static inline bool intel_pmu_needs_lbr_smpl(struct perf_event *event)
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{
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/* user explicitly requested branch sampling */
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if (has_branch_stack(event))
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return true;
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/* implicit branch sampling to correct PEBS skid */
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if (x86_pmu.intel_cap.pebs_trap && event->attr.precise_ip > 1 &&
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x86_pmu.intel_cap.pebs_format < 2)
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return true;
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return false;
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}
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static void intel_pmu_disable_all(void)
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{
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struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
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@ -1207,7 +1193,7 @@ static void intel_pmu_disable_event(struct perf_event *event)
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* must disable before any actual event
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* because any event may be combined with LBR
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*/
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if (intel_pmu_needs_lbr_smpl(event))
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if (needs_branch_stack(event))
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intel_pmu_lbr_disable(event);
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if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL)) {
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@ -1268,7 +1254,7 @@ static void intel_pmu_enable_event(struct perf_event *event)
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* must enabled before any actual event
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* because any event may be combined with LBR
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*/
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if (intel_pmu_needs_lbr_smpl(event))
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if (needs_branch_stack(event))
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intel_pmu_lbr_enable(event);
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if (event->attr.exclude_host)
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@ -1747,7 +1733,7 @@ static int intel_pmu_hw_config(struct perf_event *event)
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if (event->attr.precise_ip && x86_pmu.pebs_aliases)
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x86_pmu.pebs_aliases(event);
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if (intel_pmu_needs_lbr_smpl(event)) {
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if (needs_branch_stack(event)) {
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ret = intel_pmu_setup_lbr_filter(event);
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if (ret)
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return ret;
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@ -814,6 +814,11 @@ static inline bool has_branch_stack(struct perf_event *event)
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return event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK;
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}
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static inline bool needs_branch_stack(struct perf_event *event)
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{
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return event->attr.branch_sample_type != 0;
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}
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extern int perf_output_begin(struct perf_output_handle *handle,
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struct perf_event *event, unsigned int size);
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extern void perf_output_end(struct perf_output_handle *handle);
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@ -7232,6 +7232,9 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
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if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
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goto err_ns;
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if (!has_branch_stack(event))
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event->attr.branch_sample_type = 0;
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pmu = perf_init_event(event);
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if (!pmu)
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goto err_ns;
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