Re: [PATCH] perf jevents: return potentially empty metrics table

[Lucas Stach <l.stach@pengutronix.de>]

Hi,

has this patch fallen through the cracks? It fixes a functional
regression where the DDR controller metrics are completely unavailable
on all i.MX8M* systems and thus would be nice if someone could have a
look.

Regards,
Lucas

Am Freitag, dem 31.05.2024 um 21:44 +0200 schrieb Lucas Stach:
> Don't return NULL when a empty (num_pmus = 0) metrics table is encountered,
> as this causes many of the users to bail out, which will skip matching any
> potentially existing sys metrics later on. Instead return the empty table
> which will be handled properly by the iterators and allows matching to
> continue.
> 
> This fixes metrics reporting on systems where only the sys, but not the
> core PMUs have metrics defined.
> 
> Fixes: f20c15d13f01 ("perf pmu-events: Remember the perf_events_map for a PMU")
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> ---
>  tools/perf/pmu-events/jevents.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py
> index e42efc16723e..0a1ed9ee1429 100755
> --- a/tools/perf/pmu-events/jevents.py
> +++ b/tools/perf/pmu-events/jevents.py
> @@ -1081,7 +1081,7 @@ const struct pmu_metrics_table *perf_pmu__find_metrics_table(struct perf_pmu *pm
>          if (!map)
>                  return NULL;
>  
> -        if (!pmu)
> +        if (!pmu || !map->metric_table.num_pmus)
>                  return &map->metric_table;
>  
>          for (size_t i = 0; i < map->metric_table.num_pmus; i++) {