linux-kernel - Re: [PATCHv2 00/25] perf tool: Add support for multiple data file storage

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Date:	Tue, 10 Sep 2013 17:57:20 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Andi Kleen <ak@...ux.intel.com>,
	David Ahern <dsahern@...il.com>
Subject: Re: [PATCHv2 00/25] perf tool: Add support for multiple data file storage

Hi Peter and Jiri,

On Mon, 9 Sep 2013 13:17:49 +0200, Peter Zijlstra wrote:
> On Sun, Sep 01, 2013 at 12:36:11PM +0200, Jiri Olsa wrote:
>> hi,
>> sending the support for multiple file storage. Initial
>> RFC is here:
>> http://marc.info/?l=linux-kernel&m=137408381902423&w=2
>> 
>> v2 changes:
>>   - reworked perf mmap size setup to be able to get
>>     the mmap size value easily later
>>   - added perf.data read/write test for v2 and v3
>>     for both endianity
>>   - added record '-M time' support
>
> So this 0/n post seems to have forgotten to list the rationale for doing
> all this.. 
>
> The only reason I wanted this is so that each thread can write its own
> data. The current one file thing is an immense bottle-neck for big
> machines.

Per-thread or per-cpu?  In my perf ftrace patchset, I used to per-cpu
data file for this reason.  Do you think per-thread approach is better
than per-cpu one?

Jiri, one of my colleagues asked me about the multiple file support
separated by time while ago.  At that time I just added --time-filter
option to perf report, but it'd better if perf record can support it.
(Unfortunately the patch seems to buried in the list).

Anyway, as Peter said, please consider per-thread or per-cpu multiple
file support with your series.  It will help further developments.

Thanks,
Namhyung
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