linux-kernel - Re: [RESEND PATCH V3 2/8] perf/x86/intel: Basic support for metrics counters

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Date:   Wed, 28 Aug 2019 09:48:32 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     kan.liang@...ux.intel.com
Cc:     acme@...nel.org, mingo@...hat.com, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, jolsa@...nel.org, eranian@...gle.com,
        alexander.shishkin@...ux.intel.com, ak@...ux.intel.com
Subject: Re: [RESEND PATCH V3 2/8] perf/x86/intel: Basic support for metrics
 counters

On Mon, Aug 26, 2019 at 07:47:34AM -0700, kan.liang@...ux.intel.com wrote:
> Move BTS index to 47. Because bit 48 in the PERF_GLOBAL_STATUS is used
> to indicate the overflow status of PERF_METRICS counters now.

> diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
> index 457d35a75ad3..88a506312a10 100644
> --- a/arch/x86/include/asm/perf_event.h
> +++ b/arch/x86/include/asm/perf_event.h
> @@ -175,11 +175,56 @@ struct x86_pmu_capability {
>  /*
>   * We model BTS tracing as another fixed-mode PMC.
>   *
> - * We choose a value in the middle of the fixed event range, since lower
> + * We choose value 47 for the fixed index of BTS, since lower
>   * values are used by actual fixed events and higher values are used
>   * to indicate other overflow conditions in the PERF_GLOBAL_STATUS msr.
>   */
> -#define INTEL_PMC_IDX_FIXED_BTS				(INTEL_PMC_IDX_FIXED + 16)
> +#define INTEL_PMC_IDX_FIXED_BTS				(INTEL_PMC_IDX_FIXED + 15)

Can be its own patch.