linux-kernel - Re: [PATCH 4/4] perf: Remove unused PERF_PMU_CAP_HETEROGENEOUS

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Date:   Mon, 10 Jul 2023 09:09:01 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     James Clark <james.clark@....com>
Cc:     linux-perf-users@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, Will Deacon <will@...nel.org>,
        Kan Liang <kan.liang@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 4/4] perf: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability

On Mon, Jul 10, 2023 at 5:22 AM James Clark <james.clark@....com> wrote:
>
> Since commit bd2756811766 ("perf: Rewrite core context handling") the
> relationship between perf_event_context and PMUs has changed so that
> the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally
> silenced no longer exists.
>
> Remove the capability to avoid confusion that it actually influences
> any perf core behavior. This change should be a no-op.
>
> Signed-off-by: James Clark <james.clark@....com>

Acked-by: Ian Rogers <irogers@...gle.com>

Thanks,
Ian

> ---
>  include/linux/perf_event.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index d5628a7b5eaa..3f4d941fd6c5 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -288,7 +288,7 @@ struct perf_event_pmu_context;
>  #define PERF_PMU_CAP_EXTENDED_REGS             0x0008
>  #define PERF_PMU_CAP_EXCLUSIVE                 0x0010
>  #define PERF_PMU_CAP_ITRACE                    0x0020
> -#define PERF_PMU_CAP_HETEROGENEOUS_CPUS                0x0040
> +/* Unused                                      0x0040 */
>  #define PERF_PMU_CAP_NO_EXCLUDE                        0x0080
>  #define PERF_PMU_CAP_AUX_OUTPUT                        0x0100
>  #define PERF_PMU_CAP_EXTENDED_HW_TYPE          0x0200
> --
> 2.34.1
>