linux-kernel - Re: [PATCH v5 3/7] perf record: Move setting dummy tracking before record__init_thread

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Message-ID: <29111bbc-61af-4452-bf73-c3b32221989f@huawei.com>
Date:   Tue, 15 Aug 2023 09:57:35 +0800
From:   Yang Jihong <yangjihong1@...wei.com>
To:     Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>
CC:     <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
        <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
        <jolsa@...nel.org>, <namhyung@...nel.org>,
        <kan.liang@...ux.intel.com>, <james.clark@....com>,
        <tmricht@...ux.ibm.com>, <ak@...ux.intel.com>,
        <anshuman.khandual@....com>, <linux-kernel@...r.kernel.org>,
        <linux-perf-users@...r.kernel.org>
Subject: Re: [PATCH v5 3/7] perf record: Move setting dummy tracking before
 record__init_thread_masks()

Hello,

On 2023/8/15 4:29, Ian Rogers wrote:
> On Thu, Aug 3, 2023 at 11:58 PM Adrian Hunter <adrian.hunter@...el.com> wrote:
>>
>> On 4/08/23 05:07, Yang Jihong wrote:
>>> When dummy tracking go system wide, the mmap cpu mask is changed.
> 
> As previously commented, can we improve the quality of the function
> names and commit messages? This sentence is particularly difficult to
> understand, I don't understand it.

OK. The commit messages will be modified. Please check whether the 
following description is clear:

User space tasks can migrate between CPUs, so when tracing selected 
CPUs, sideband for all CPUs is needed. In this case set the cpu map of 
the evsel to all online CPUs. This may modify the original cpu map of 
the evlist.
Therefore, need to check whether the preceding scenario exists before 
record__init_thread_masks().
Dummy tracking has been set in record__open(), move it before 
record__init_thread_masks() and add a helper for unified processing.

Thanks,
Yang