linux-kernel - Re: [PATCH 2/4] perf/x86: Remove unused PERF_PMU_CAP_HETEROGENEOUS

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Message-ID: <CAP-5=fU_pr98phNSrbaeoHoeDPrTPeC3S1c2Z-vOG-FBWn_F5Q@mail.gmail.com>
Date:   Mon, 10 Jul 2023 09:07:50 -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 2/4] perf/x86: 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

> ---
>  arch/x86/events/core.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
> index 9d248703cbdd..2353aaf0b248 100644
> --- a/arch/x86/events/core.c
> +++ b/arch/x86/events/core.c
> @@ -2168,7 +2168,6 @@ static int __init init_hw_perf_events(void)
>                         hybrid_pmu->pmu = pmu;
>                         hybrid_pmu->pmu.type = -1;
>                         hybrid_pmu->pmu.attr_update = x86_pmu.attr_update;
> -                       hybrid_pmu->pmu.capabilities |= PERF_PMU_CAP_HETEROGENEOUS_CPUS;
>                         hybrid_pmu->pmu.capabilities |= PERF_PMU_CAP_EXTENDED_HW_TYPE;
>
>                         err = perf_pmu_register(&hybrid_pmu->pmu, hybrid_pmu->name,
> --
> 2.34.1
>