Messages in this thread Patch in this message | | | From | kan.liang@intel ... | Subject | [PATCH V2 04/13] perf/core: output multiplexing overhead | Date | Fri, 2 Dec 2016 16:19:12 -0500 |
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From: Kan Liang <kan.liang@intel.com>
Multiplexing overhead is one of the key overhead when the number of events is more than available counters.
The multiplexing overhead PERF_CORE_MUX_OVERHEAD is a common overhead type.
Signed-off-by: Kan Liang <kan.liang@intel.com> --- include/linux/perf_event.h | 2 ++ include/uapi/linux/perf_event.h | 1 + kernel/events/core.c | 14 ++++++++++++++ 3 files changed, 17 insertions(+)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index ebd356e..351d321 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -794,6 +794,8 @@ struct perf_cpu_context { struct list_head sched_cb_entry; int sched_cb_usage; + + struct perf_overhead_entry mux_overhead; }; struct perf_output_handle { diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index fe7b1fb..355086f 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -999,6 +999,7 @@ struct perf_branch_entry { */ enum perf_record_overhead_type { PERF_CORE_OVERHEAD = 0, + PERF_CORE_MUX_OVERHEAD = 0, PERF_PMU_OVERHEAD = 20, PERF_PMU_SAMPLE_OVERHEAD = 20, diff --git a/kernel/events/core.c b/kernel/events/core.c index 306bc92..025a19d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1830,6 +1830,9 @@ event_sched_out(struct perf_event *event, if (event->attr.exclusive || !cpuctx->active_oncpu) cpuctx->exclusive = 0; + if (log_overhead && cpuctx->mux_overhead.nr) + perf_log_overhead(event, PERF_CORE_MUX_OVERHEAD, &cpuctx->mux_overhead); + perf_pmu_enable(event->pmu); } @@ -3330,9 +3333,17 @@ static void rotate_ctx(struct perf_event_context *ctx) list_rotate_left(&ctx->flexible_groups); } +static void +perf_calculate_mux_overhead(struct perf_cpu_context *cpuctx, u64 time) +{ + cpuctx->mux_overhead.nr++; + cpuctx->mux_overhead.time += time; +} + static int perf_rotate_context(struct perf_cpu_context *cpuctx) { struct perf_event_context *ctx = NULL; + u64 start_clock, end_clock; int rotate = 0; if (cpuctx->ctx.nr_events) { @@ -3349,6 +3360,7 @@ static int perf_rotate_context(struct perf_cpu_context *cpuctx) if (!rotate) goto done; + start_clock = perf_clock(); perf_ctx_lock(cpuctx, cpuctx->task_ctx); perf_pmu_disable(cpuctx->ctx.pmu); @@ -3364,6 +3376,8 @@ static int perf_rotate_context(struct perf_cpu_context *cpuctx) perf_pmu_enable(cpuctx->ctx.pmu); perf_ctx_unlock(cpuctx, cpuctx->task_ctx); + end_clock = perf_clock(); + perf_calculate_mux_overhead(cpuctx, end_clock - start_clock); done: return rotate; -- 2.5.5
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