Messages in this thread | | | Date | Mon, 6 Nov 2023 16:19:13 -0500 | Subject | Re: [PATCH V5 2/8] perf/x86: Add PERF_X86_EVENT_NEEDS_BRANCH_STACK flag | From | "Liang, Kan" <> |
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On 2023-11-06 4:12 p.m., Arnaldo Carvalho de Melo wrote: > Em Wed, Oct 25, 2023 at 01:16:20PM -0700, kan.liang@linux.intel.com escreveu: >> From: Kan Liang <kan.liang@linux.intel.com> >> >> Currently, branch_sample_type !=0 is used to check whether a branch >> stack setup is required. But it doesn't check the sample type, >> unnecessary branch stack setup may be done for a counting event. E.g., >> perf record -e "{branch-instructions,branch-misses}:S" -j any >> Also, the event only with the new PERF_SAMPLE_BRANCH_COUNTERS branch >> sample type may not require a branch stack setup either. >> >> Add a new flag NEEDS_BRANCH_STACK to indicate whether the event requires >> a branch stack setup. Replace the needs_branch_stack() by checking the >> new flag. >> >> The counting event check is implemented here. The later patch will take >> the new PERF_SAMPLE_BRANCH_COUNTERS into account. >> >> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> >> --- >> >> No changes since V4 > > So I saw this on tip/perf/urgent, I'm picking the tools bits then.
Thanks Arnaldo.
Ian has already reviewed the tool parts.
But I still owe a test case for the feature. I will post a patch later. https://lore.kernel.org/lkml/acbb895a-475e-4679-98fc-6b90c05a00af@linux.intel.com/
Thanks, Kan
> > - Arnaldo > >> arch/x86/events/intel/core.c | 14 +++++++++++--- >> arch/x86/events/perf_event_flags.h | 1 + >> 2 files changed, 12 insertions(+), 3 deletions(-) >> >> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c >> index 41a164764a84..a99449c0d77c 100644 >> --- a/arch/x86/events/intel/core.c >> +++ b/arch/x86/events/intel/core.c >> @@ -2527,9 +2527,14 @@ static void intel_pmu_assign_event(struct perf_event *event, int idx) >> perf_report_aux_output_id(event, idx); >> } >> >> +static __always_inline bool intel_pmu_needs_branch_stack(struct perf_event *event) >> +{ >> + return event->hw.flags & PERF_X86_EVENT_NEEDS_BRANCH_STACK; >> +} >> + >> static void intel_pmu_del_event(struct perf_event *event) >> { >> - if (needs_branch_stack(event)) >> + if (intel_pmu_needs_branch_stack(event)) >> intel_pmu_lbr_del(event); >> if (event->attr.precise_ip) >> intel_pmu_pebs_del(event); >> @@ -2820,7 +2825,7 @@ static void intel_pmu_add_event(struct perf_event *event) >> { >> if (event->attr.precise_ip) >> intel_pmu_pebs_add(event); >> - if (needs_branch_stack(event)) >> + if (intel_pmu_needs_branch_stack(event)) >> intel_pmu_lbr_add(event); >> } >> >> @@ -3897,7 +3902,10 @@ static int intel_pmu_hw_config(struct perf_event *event) >> x86_pmu.pebs_aliases(event); >> } >> >> - if (needs_branch_stack(event)) { >> + if (needs_branch_stack(event) && is_sampling_event(event)) >> + event->hw.flags |= PERF_X86_EVENT_NEEDS_BRANCH_STACK; >> + >> + if (intel_pmu_needs_branch_stack(event)) { >> ret = intel_pmu_setup_lbr_filter(event); >> if (ret) >> return ret; >> diff --git a/arch/x86/events/perf_event_flags.h b/arch/x86/events/perf_event_flags.h >> index 1dc19b9b4426..a1685981c520 100644 >> --- a/arch/x86/events/perf_event_flags.h >> +++ b/arch/x86/events/perf_event_flags.h >> @@ -20,3 +20,4 @@ PERF_ARCH(TOPDOWN, 0x04000) /* Count Topdown slots/metrics events */ >> PERF_ARCH(PEBS_STLAT, 0x08000) /* st+stlat data address sampling */ >> PERF_ARCH(AMD_BRS, 0x10000) /* AMD Branch Sampling */ >> PERF_ARCH(PEBS_LAT_HYBRID, 0x20000) /* ld and st lat for hybrid */ >> +PERF_ARCH(NEEDS_BRANCH_STACK, 0x40000) /* require branch stack setup */ >> -- >> 2.35.1 >> >
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