linux-kernel - Re: [PATCH 2/2] perf/core: Remove perf_cpu_context::unique

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Date:   Wed, 18 Jan 2017 12:25:15 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     David Carrillo-Cisneros <davidcc@...gle.com>
Cc:     linux-kernel@...r.kernel.org, "x86@...nel.org" <x86@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andi Kleen <ak@...ux.intel.com>,
        Kan Liang <kan.liang@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...e.de>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Vince Weaver <vince@...ter.net>, Paul Turner <pjt@...gle.com>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 2/2] perf/core: Remove perf_cpu_context::unique_pmu

On Tue, Jan 17, 2017 at 09:38:40AM -0800, David Carrillo-Cisneros wrote:
> cpuctx->unique_pmu was originally introduced as a way to identify cpuctxs
> with shared pmus in order to avoid visiting the same cpuctx more than once
> in a for_each_pmu loop.
> 
> cpuctx->unique_pmu == cpuctx->pmu in non-software task contexts since they
> have only one pmu per cpuctx. Since perf_pmu_sched_task is only called in
> hw contexts, this patch replaces cpuctx->unique_pmu by cpuctx->pmu in it.
> 
> The change above, together with the previous patch in this series, removed
> the remaining uses of cpuctx->unique_pmu, so we remove it altogether.
> 
> Signed-off-by: David Carrillo-Cisneros <davidcc@...gle.com>

I don't have any HW with a PMU that needs a sched_task callback, so I'm
unable to give this a full test, but it looks sane to me. FWIW:

Acked-by: Mark Rutland <mark.rutland@....com>

Thanks,
Mark.