linux-kernel - Re: [PATCH V2 07/14] perf tools: Add evsel->own

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Date:	Tue, 8 Sep 2015 10:09:10 +0300
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Arnaldo Carvalho de Melo <acme@...hat.com>, mingo@...nel.org,
	kan.liang@...el.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 07/14] perf tools: Add evsel->own_cpus

On 08/09/15 09:45, Jiri Olsa wrote:
> On Mon, Sep 07, 2015 at 05:27:49PM +0300, Adrian Hunter wrote:
>> perf_evlist__propagate_maps() cannot easily tell if an evsel
>> has its own cpu map.  To make that simpler, keep a copy of
>> the PMU cpu map and adjust the propagation logic accordingly.
>>
>> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
>> ---
>>  tools/perf/util/evlist.c       | 5 ++++-
>>  tools/perf/util/evsel.c        | 1 +
>>  tools/perf/util/evsel.h        | 1 +
>>  tools/perf/util/parse-events.c | 4 ++--
>>  4 files changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
>> index c959c42080e3..6764e0eff849 100644
>> --- a/tools/perf/util/evlist.c
>> +++ b/tools/perf/util/evlist.c
>> @@ -1111,9 +1111,12 @@ static void perf_evlist__propagate_maps(struct perf_evlist *evlist)
>>  		 * We already have cpus for evsel (via PMU sysfs) so
>>  		 * keep it, if there's no target cpu list defined.
>>  		 */
>> -		if (!evsel->cpus || evlist->has_user_cpus) {
>> +		if (!evsel->own_cpus || evlist->has_user_cpus) {
>>  			cpu_map__put(evsel->cpus);
>>  			evsel->cpus = cpu_map__get(evlist->cpus);
>> +		} else if (evsel->cpus != evsel->own_cpus) {
>> +			cpu_map__put(evsel->cpus);
>> +			evsel->cpus = cpu_map__get(evsel->own_cpus);
> 
> hum, so (evsel->cpus != evsel->own_cpus) could happen only when:
>   - evsel->own_cpus != NULL
>   - we overloaded evsel->cpus with evlist->cpus via perf_evlist__propagate_maps
>   - we changed evlist->has_user_cpus = false
>   - we recall perf_evlist__propagate_maps
> 
> I'm missing usecase for that, or something else ;-)

That's true but the idea is to establish rules (invariants) that are always
true.  Like an evsel either has its own cpu map or the same as the evlist.

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