linux-kernel - Re: [PATCH 2/5] libperf: Propagate maps only if necessary

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Date:   Tue, 4 Oct 2022 16:55:49 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        linux-perf-users@...r.kernel.org,
        Kan Liang <kan.liang@...ux.intel.com>,
        Leo Yan <leo.yan@...aro.org>
Subject: Re: [PATCH 2/5] libperf: Propagate maps only if necessary

On 4/10/22 15:14, Arnaldo Carvalho de Melo wrote:
> Em Mon, Oct 03, 2022 at 01:46:44PM -0700, Namhyung Kim escreveu:
>> The current code propagate evsel's cpu map settings to evlist when it's
>> added to an evlist.  But the evlist->all_cpus and each evsel's cpus will
>> be updated in perf_evlist__set_maps() later.  No need to do it before
>> evlist's cpus are set actually.
>>
>> In fact it discards this intermediate all_cpus maps at the beginning
>> of perf_evlist__set_maps().  Let's not do this.  It's only needed when
>> an evsel is added after the evlist cpu/thread maps are set.
>>
>> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
>> ---
>>  tools/lib/perf/evlist.c                  | 11 ++++-------
>>  tools/lib/perf/include/internal/evlist.h |  1 +
>>  2 files changed, 5 insertions(+), 7 deletions(-)
>>
>> diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
>> index 187129652ab6..8ce92070086c 100644
>> --- a/tools/lib/perf/evlist.c
>> +++ b/tools/lib/perf/evlist.c
>> @@ -67,9 +67,7 @@ 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;
>> +	evlist->needs_map_propagation = true;
>>  
>>  	perf_evlist__for_each_evsel(evlist, evsel)
>>  		__perf_evlist__propagate_maps(evlist, evsel);
>> @@ -81,7 +79,9 @@ void perf_evlist__add(struct perf_evlist *evlist,
>>  	evsel->idx = evlist->nr_entries;
>>  	list_add_tail(&evsel->node, &evlist->entries);
>>  	evlist->nr_entries += 1;
>> -	__perf_evlist__propagate_maps(evlist, evsel);
>> +
>> +	if (evlist->needs_map_propagation)
>> +		__perf_evlist__propagate_maps(evlist, evsel);
>>  }
>>  
>>  void perf_evlist__remove(struct perf_evlist *evlist,
>> @@ -177,9 +177,6 @@ void perf_evlist__set_maps(struct perf_evlist *evlist,
>>  		evlist->threads = perf_thread_map__get(threads);
>>  	}
>>  
>> -	if (!evlist->all_cpus && cpus)
>> -		evlist->all_cpus = perf_cpu_map__get(cpus);
>> -
>>  	perf_evlist__propagate_maps(evlist);
> 
> IIRC Adrian suggested this extra thing, but he provided the Reviewed-by
> for the previous patch, where this isn't present, Adrian, can you please
> confirm this and if this is the case provide your Reviewed-by for this
> new version?

Oops sorry, I meant this one:

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


> 
> Thanks,
> 
> - Arnaldo
> 
>>  }
>>  
>> diff --git a/tools/lib/perf/include/internal/evlist.h b/tools/lib/perf/include/internal/evlist.h
>> index 6f89aec3e608..850f07070036 100644
>> --- a/tools/lib/perf/include/internal/evlist.h
>> +++ b/tools/lib/perf/include/internal/evlist.h
>> @@ -19,6 +19,7 @@ struct perf_evlist {
>>  	int			 nr_entries;
>>  	int			 nr_groups;
>>  	bool			 has_user_cpus;
>> +	bool			 needs_map_propagation;
>>  	/**
>>  	 * The cpus passed from the command line or all online CPUs by
>>  	 * default.
>> -- 
>> 2.38.0.rc1.362.ged0d419d3c-goog
>