linux-kernel - Re: [PATCH v5 2/6] perf evlist: Clear all

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Date:   Wed, 4 May 2022 17:15:57 +0300
From:   Adrian Hunter <adrian.hunter@...el.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>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Kajol Jain <kjain@...ux.ibm.com>,
        James Clark <james.clark@....com>,
        German Gomez <german.gomez@....com>,
        Riccardo Mancini <rickyman7@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
        Alexander Antonov <alexander.antonov@...ux.intel.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v5 2/6] perf evlist: Clear all_cpus before propagating

On 3/05/22 07:17, Ian Rogers wrote:
> all_cpus is merged into during propagation. Initially all_cpus is set
> from PMU sysfs. perf_evlist__set_maps will recompute it and change
> evsel->cpus to user_requested_cpus if they are given. If all_cpus isn't
> cleared then the union of the user_requested_cpus and PMU sysfs values
> is set to all_cpus, whereas just user_requested_cpus is necessary. To
> avoid this make all_cpus empty prior to propagation.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>

Reviewed-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
>  tools/lib/perf/evlist.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
> index a09315538a30..974b4585f93e 100644
> --- a/tools/lib/perf/evlist.c
> +++ b/tools/lib/perf/evlist.c
> @@ -59,6 +59,10 @@ static void perf_evlist__propagate_maps(struct perf_evlist *evlist)
>  {
>  	struct perf_evsel *evsel;
>  
> +	/* Recomputing all_cpus, so start with a blank slate. */
> +	perf_cpu_map__put(evlist->all_cpus);
> +	evlist->all_cpus = NULL;
> +
>  	perf_evlist__for_each_evsel(evlist, evsel)
>  		__perf_evlist__propagate_maps(evlist, evsel);
>  }