On Fri, Dec 02, 2016 at 04:19:12PM -0500, [email protected] wrote:
> From: Kan Liang <[email protected]>
>
> 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.
>
> 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,
'0' already had a name ?!
>
> PERF_PMU_OVERHEAD = 20,
> PERF_PMU_SAMPLE_OVERHEAD = 20,
Same here I suppose, why are there two with the same name?
> 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);
> +
This isn't mentioned in the Changelog. Why is it here?
> perf_pmu_enable(event->pmu);
> }
>
