linux-kernel - Re: [PATCH v6 5/6] perf vendor events arm64: Update stall

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Date:   Thu, 17 Aug 2023 12:08:00 +0100
From:   John Garry <john.g.garry@...cle.com>
To:     James Clark <james.clark@....com>,
        linux-perf-users@...r.kernel.org, irogers@...gle.com,
        renyu.zj@...ux.alibaba.com, acme@...nel.org
Cc:     Will Deacon <will@...nel.org>, Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        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>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Haixin Yu <yuhaixin.yhx@...ux.alibaba.com>,
        Nick Forrington <nick.forrington@....com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Eduard Zingerman <eddyz87@...il.com>,
        Sohom Datta <sohomdatta1@...il.com>,
        Rob Herring <robh@...nel.org>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v6 5/6] perf vendor events arm64: Update stall_slot
 workaround for N2 r0p3

On 16/08/2023 12:47, James Clark wrote:
> N2 r0p3 doesn't require the workaround [1], so gating on (#slots - 5) no
> longer works because all N2s have 5 slots. Use the new expression
> builtin that allows calling strcmp_cpuid_str() and comparing CPUIDs in
> metric formulas.
> 
> In this case, the commented formula looks like this:
> 
>    strcmp_cpuid_str(0x410fd493)        # greater than or equal to N2 r0p3
>    | strcmp_cpuid_str(0x410fd490) ^ 1  # OR NOT any version of N2
> 
> [1]:https://urldefense.com/v3/__https://gitlab.arm.com/telemetry-solution/telemetry-solution/-/blob/main/data/pmu/cpu/neoverse/neoverse-n2-r0p3.json__;!!ACWV5N9M2RV99hQ!JvpXOAN-7zsKcA750zS-vMlcJKvvIZ_H9zg6jitWJRMitlFGDrx8bXoMrhdK5ubhO8CtXObRFx7bDYM2R5Feqg$  
> Signed-off-by: James Clark<james.clark@....com>
> ---

Reviewed-by: John Garry <john.g.garry@...cle.com>