Messages in this thread Patch in this message | | | From | kan.liang@intel ... | Subject | [PATCH V2 03/13] perf/x86: output sampling overhead | Date | Fri, 2 Dec 2016 16:19:11 -0500 |
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From: Kan Liang <kan.liang@intel.com>
On x86, NMI handler is the most important part which brings overhead for sampling. Adding a pmu specific overhead type PERF_PMU_SAMPLE_OVERHEAD for it.
For other architectures which may don't have NMI, the overhead type can be reused.
Signed-off-by: Kan Liang <kan.liang@intel.com> --- arch/x86/events/core.c | 17 ++++++++++++++++- arch/x86/events/perf_event.h | 2 ++ include/uapi/linux/perf_event.h | 1 + 3 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 9d4bf3a..de40f96 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -1397,6 +1397,9 @@ static void x86_pmu_del(struct perf_event *event, int flags) perf_event_update_userpage(event); + if ((flags & PERF_EF_LOG) && cpuc->nmi_overhead.nr) + perf_log_overhead(event, PERF_PMU_SAMPLE_OVERHEAD, &cpuc->nmi_overhead); + do_del: if (x86_pmu.del) { /* @@ -1475,11 +1478,21 @@ void perf_events_lapic_init(void) apic_write(APIC_LVTPC, APIC_DM_NMI); } +static void +perf_calculate_nmi_overhead(u64 time) +{ + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); + + cpuc->nmi_overhead.nr++; + cpuc->nmi_overhead.time += time; +} + static int perf_event_nmi_handler(unsigned int cmd, struct pt_regs *regs) { u64 start_clock; u64 finish_clock; + u64 clock; int ret; /* @@ -1492,8 +1505,10 @@ perf_event_nmi_handler(unsigned int cmd, struct pt_regs *regs) start_clock = sched_clock(); ret = x86_pmu.handle_irq(regs); finish_clock = sched_clock(); + clock = finish_clock - start_clock; - perf_sample_event_took(finish_clock - start_clock); + perf_calculate_nmi_overhead(clock); + perf_sample_event_took(clock); return ret; } diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index a77ee02..7a03384 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -230,6 +230,8 @@ struct cpu_hw_events { struct intel_excl_cntrs *excl_cntrs; int excl_thread_id; /* 0 or 1 */ + struct perf_overhead_entry nmi_overhead; + /* * AMD specific bits */ diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index bb0ecf0..fe7b1fb 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -1001,6 +1001,7 @@ enum perf_record_overhead_type { PERF_CORE_OVERHEAD = 0, PERF_PMU_OVERHEAD = 20, + PERF_PMU_SAMPLE_OVERHEAD = 20, PERF_OVERHEAD_MAX, }; -- 2.5.5
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