Re: [PATCH 1/3] perf: add a dummy software event to keep tracking

From: Adrian Hunter
Date: Mon Aug 26 2013 - 09:09:22 EST


On 07/08/13 16:30, Adrian Hunter wrote:
> When an event is disabled the "tracking" events
> selected by the 'mmap', 'comm' and 'task' bits of
> struct perf_event_attr, are also disabled. However,
> the information those events provide is necessary to
> resolve symbols for when the main event is re-enabled.
>
> The "tracking" events can be kept enabled by putting
> them on another event, but that requires an event
> that otherwise does nothing. A new software event
> PERF_COUNT_SW_DUMMY is added for that purpose.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>

Any comments?

> ---
> include/uapi/linux/perf_event.h | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index 62c25a2..9e28422 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -109,6 +109,7 @@ enum perf_sw_ids {
> PERF_COUNT_SW_PAGE_FAULTS_MAJ = 6,
> PERF_COUNT_SW_ALIGNMENT_FAULTS = 7,
> PERF_COUNT_SW_EMULATION_FAULTS = 8,
> + PERF_COUNT_SW_DUMMY = 9,
>
> PERF_COUNT_SW_MAX, /* non-ABI */
> };
>

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