linux-kernel - Re: [PATCH v1 2/2] perf pmu: Remove a hard coded cpu PMU assumption

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Date:   Thu, 22 Jun 2023 10:35:56 +0200
From:   Thomas Richter <tmricht@...ux.ibm.com>
To:     Ian Rogers <irogers@...gle.com>,
        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>,
        Kan Liang <kan.liang@...ux.intel.com>,
        James Clark <james.clark@....com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/2] perf pmu: Remove a hard coded cpu PMU assumption

On 6/22/23 07:03, Ian Rogers wrote:
> The property of "cpu" when it has no cpu map is true on S390 with the
> PMU cpum_cf. Rather than maintain a list of such PMUs, reuse the
> is_core test result from the caller.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/util/pmu.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 963c12f910c5..64fa568a5426 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -551,7 +551,7 @@ static int pmu_alias_terms(struct perf_pmu_alias *alias,
>   * Uncore PMUs have a "cpumask" file under sysfs. CPU PMUs (e.g. on arm/arm64)
>   * may have a "cpus" file.
>   */
> -static struct perf_cpu_map *pmu_cpumask(int dirfd, const char *name)
> +static struct perf_cpu_map *pmu_cpumask(int dirfd, const char *name, bool is_core)
>  {
>  	struct perf_cpu_map *cpus;
>  	const char *templates[] = {
> @@ -575,7 +575,8 @@ static struct perf_cpu_map *pmu_cpumask(int dirfd, const char *name)
>  			return cpus;
>  	}
>  
> -	return !strcmp(name, "cpu") ? perf_cpu_map__get(cpu_map__online()) : NULL;
> +	/* Nothing found, for core PMUs assume this means all CPUs. */
> +	return is_core ? perf_cpu_map__get(cpu_map__online()) : NULL;
>  }
>  
>  static bool pmu_is_uncore(int dirfd, const char *name)
> @@ -886,7 +887,8 @@ struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char
>  	if (!pmu)
>  		return NULL;
>  
> -	pmu->cpus = pmu_cpumask(dirfd, name);
> +	pmu->is_core = is_pmu_core(name);
> +	pmu->cpus = pmu_cpumask(dirfd, name, pmu->is_core);
>  	pmu->name = strdup(name);
>  	if (!pmu->name)
>  		goto err;
> @@ -903,7 +905,6 @@ struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char
>  	}
>  
>  	pmu->type = type;
> -	pmu->is_core = is_pmu_core(name);
>  	pmu->is_uncore = pmu_is_uncore(dirfd, name);
>  	if (pmu->is_uncore)
>  		pmu->id = pmu_id(name);

Looks good to me, for both patches:

Tested-by: Thomas Richter <tmricht@...ux.ibm.com>
-- 
Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany
--
Vorsitzender des Aufsichtsrats: Gregor Pillen
Geschäftsführung: David Faller
Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294