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Subject: Re: [PATCH v5 13/13] perf record: introduce --ctl-fd[-ack] options
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>
 <20200601233732.GA691017@tassilo.jf.intel.com>
From:   Alexey Budankov <alexey.budankov@linux.intel.com>
Organization: Intel Corp.
Message-ID: <1bc7c72b-9d78-5184-a27c-8025beadaaf0@linux.intel.com>
Date:   Tue, 2 Jun 2020 11:32:47 +0300
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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

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
>>