Re: [PATCH] perf stat: Fix the hard-coded metrics calculation on the hybrid

[Ian Rogers]

On Wed, Jun 5, 2024 at 9:10 AM <kan.liang@xxxxxxxxxxxxxxx> wrote:
>
> From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
>
> The hard-coded metrics is wrongly calculated on the hybrid machine.
>
> $ perf stat -e cycles,instructions -a sleep 1
>
>  Performance counter stats for 'system wide':
>
>         18,205,487      cpu_atom/cycles/
>          9,733,603      cpu_core/cycles/
>          9,423,111      cpu_atom/instructions/     #  0.52  insn per cycle
>          4,268,965      cpu_core/instructions/     #  0.23  insn per cycle
>
> The insn per cycle for cpu_core should be 4,268,965 / 9,733,603 = 0.44.
>
> When finding the metric events, the find_stat() doesn't take the PMU
> type into account. The cpu_atom/cycles/ is wrongly used to calculate
> the IPC of the cpu_core.
>
> Fixes: 0a57b910807a ("perf stat: Use counts rather than saved_value")
> Reported-by: "Khalil, Amiri" <amiri.khalil@xxxxxxxxx>
> Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> Cc: stable@xxxxxxxxxxxxxxx
> ---
>  tools/perf/util/stat-shadow.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
> index 3466aa952442..4d0edc061f1a 100644
> --- a/tools/perf/util/stat-shadow.c
> +++ b/tools/perf/util/stat-shadow.c
> @@ -176,6 +176,10 @@ static double find_stat(const struct evsel *evsel, int aggr_idx, enum stat_type
>                 if (type != evsel__stat_type(cur))
>                         continue;
>
> +               /* Ignore if not the PMU we're looking for. */
> +               if (evsel->pmu != cur->pmu)
> +                       continue;
> +
>                 aggr = &cur->stats->aggr[aggr_idx];
>                 if (type == STAT_NSECS)
>                         return aggr->counts.val;
> --
> 2.35.1
>