Re: [PATCH RFC 2/9] perf metrics: Don't iter sys metrics if we already found a CPU match

From: Ian Rogers
Date: Fri Jun 30 2023 - 13:41:19 EST


On Wed, Jun 28, 2023 at 3:30 AM John Garry <john.g.garry@xxxxxxxxxx> wrote:
>
> In metricgroup__add_metric() we still iter the sys metrics if we already
> found a match from the CPU table, which is pretty pointless, so don't
> bother.
>
> Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
> ---
> tools/perf/util/metricgroup.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> index 4389ccd29fe7..8d2ac2513530 100644
> --- a/tools/perf/util/metricgroup.c
> +++ b/tools/perf/util/metricgroup.c
> @@ -1261,6 +1261,12 @@ static int metricgroup__add_metric(const char *pmu, const char *metric_name, con
>
> has_match = data.has_match;
> }
> +
> + if (has_match) {
> + ret = 0;
> + goto out;
> + }
> +

I think this can just be:

if (!has_match)

However, I'm not sure I agree with the intent of the change. We may
have a metric like IPC and want it to apply to all types of CPU, GPU,
etc. If we short-cut here then that won't be possible.

Thanks,
Ian
> {
> struct metricgroup_iter_data data = {
> .fn = metricgroup__add_metric_sys_event_iter,
> @@ -1279,6 +1285,7 @@ static int metricgroup__add_metric(const char *pmu, const char *metric_name, con
>
> pmu_for_each_sys_metric(metricgroup__sys_event_iter, &data);
> }
> +
> /* End of pmu events. */
> if (!has_match)
> ret = -EINVAL;
> --
> 2.35.3
>