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Subject: Re: [PATCH v6 1/7] perf evlist: Add perf_evlist__go_system_wide()
 helper
To:     Ian Rogers <irogers@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>
CC:     <peterz@infradead.org>, <mingo@redhat.com>, <acme@kernel.org>,
        <mark.rutland@arm.com>, <alexander.shishkin@linux.intel.com>,
        <jolsa@kernel.org>, <namhyung@kernel.org>,
        <kan.liang@linux.intel.com>, <james.clark@arm.com>,
        <tmricht@linux.ibm.com>, <ak@linux.intel.com>,
        <anshuman.khandual@arm.com>, <linux-kernel@vger.kernel.org>,
        <linux-perf-users@vger.kernel.org>
References: <20230821012734.18241-1-yangjihong1@huawei.com>
 <20230821012734.18241-2-yangjihong1@huawei.com>
 <CAP-5=fXexLBnq1pkHPR5uXR-bL3CFTzEWkFnxHVs-71+S0yZSg@mail.gmail.com>
From:   Yang Jihong <yangjihong1@huawei.com>
Message-ID: <db2de7d0-d60d-33f8-3587-c776a3eb8fce@huawei.com>
Date:   Fri, 25 Aug 2023 13:41:06 +0800
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Hello,

On 2023/8/25 12:51, Ian Rogers wrote:
> On Sun, Aug 20, 2023 at 6:30 PM Yang Jihong <yangjihong1@huawei.com> wrote:
>>
>> For dummy events that keep tracking, we may need to modify its cpu_maps.
>> For example, change the cpu_maps to record sideband events for all CPUS.
>> Add perf_evlist__go_system_wide() helper to support this scenario.
>>
>> Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
>> Acked-by: Adrian Hunter <adrian.hunter@intel.com>
>> ---
>>   tools/lib/perf/evlist.c                  | 9 +++++++++
>>   tools/lib/perf/include/internal/evlist.h | 2 ++
>>   2 files changed, 11 insertions(+)
>>
>> diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
>> index b8b066d0dc5e..3acbbccc1901 100644
>> --- a/tools/lib/perf/evlist.c
>> +++ b/tools/lib/perf/evlist.c
>> @@ -738,3 +738,12 @@ int perf_evlist__nr_groups(struct perf_evlist *evlist)
>>          }
>>          return nr_groups;
>>   }
>> +
>> +void perf_evlist__go_system_wide(struct perf_evlist *evlist, struct perf_evsel *evsel)
>> +{
>> +       if (!evsel->system_wide) {
>> +               evsel->system_wide = true;
>> +               if (evlist->needs_map_propagation)
>> +                       __perf_evlist__propagate_maps(evlist, evsel);
>> +       }
>> +}
> 
> I think this should be:
> 
> void evsel__set_system_wide(struct evsel *evsel)
> {
>          if (evsel->system_wide)
>                 return;
>          evsel->system_wide = true;
>          if (evsel->evlist->core.needs_map_propagation)
> ...
> 
> The API being on evlist makes it look like all evsels are affected.
> 
This part of the code is implemented according to Adrian's suggestion.
Refer to:

https://lore.kernel.org/linux-perf-users/206972a3-d44d-1c75-3fbc-426427614543@intel.com/

The logic of both is the same, and either is OK for me.
If really want to change it, please let me know.

Thanks,
Yang