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Subject: Re: [PATCH v5 13/13] perf record: introduce --ctl-fd[-ack] options
From:   Alexey Budankov <alexey.budankov@linux.intel.com>
To:     Andi Kleen <ak@linux.intel.com>,
        Adrian Hunter <adrian.hunter@intel.com>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
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 <937c8cc1-b4c2-8531-3fa4-d0ad9df6a65f@linux.intel.com>
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 <1bc7c72b-9d78-5184-a27c-8025beadaaf0@linux.intel.com>
Organization: Intel Corp.
Message-ID: <d7924d7c-e2e5-c067-b9e0-cfea919e7780@linux.intel.com>
Date:   Tue, 2 Jun 2020 12:12:24 +0300
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On 02.06.2020 11:32, Alexey Budankov wrote:
> 
> On 02.06.2020 2:37, Andi Kleen wrote:
>>>> or a pathname, or including also the event default of "disabled".
>>>
>>> For my cases conversion of pathnames into open fds belongs to external
>>> controlling process e.g. like in the examples provided in the patch set.
>>> Not sure about "event default of 'disabled'"
>>
>> It would be nicer for manual use cases if perf supported the path names
>> directly like in Adrian's example, not needing a complex wrapper script.
> 
> fds interface is required for VTune integration since VTune wants control
> over files creation aside of Perf tool process. The script demonstrates
> just one possible use case.
> 
> Control files could easily be implemented on top of fds making open operations
> for paths and then initializing fds. Interface below is vague and with explicit
> options like below it could be more explicit:
> --ctl-file /tmp/my-perf.fifo --ctl-file-ack /tmp/my-perf-ack.fifo

Or even clearer:

--ctl-fifo /tmp/my-perf --ctl-fifo-ack /tmp/my-perf-ack

> 
> Make either fds and or files provided on the command line. Implement file
> options handling callbacks that would open paths and setting fds. Close fds
> if they were opened by Perf tool process.
> 
> Adrian, please share your mind and use case.
> 
> ~Alexey
> 
>>
>> -Andi
>>>
>>>>
>>>> e.g. add "--control" and support all of:
>>>>
>>>> --control
>>>> --control 11
>>>> --control 11,15
>>>> --control 11,15,disabled
>>>> --control 11,,disabled
>>>> --control /tmp/my-perf.fifo
>>>> --control /tmp/my-perf.fifo,/tmp/my-perf-ack.fifo
>>>> --control /tmp/my-perf.fifo,/tmp/my-perf-ack.fifo,disabled
>>>> --control /tmp/my-perf.fifo,,disabled
>>>>
>>>> Regards
>>>> Adrian
>>>>
>>>
>>> Regards,
>>> Alexey
>>>