linux-kernel - Re: [PATCH] perf lock: clean the options for perf record

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Message-ID: <20110304135635.GB1972@nowhere>
Date:	Fri, 4 Mar 2011 14:56:39 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Hitoshi Mitake <mitake@....info.waseda.ac.jp>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org, h.mitake@...il.com,
	Paul Mackerras <paulus@...ba.org>, Ingo Molnar <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH] perf lock: clean the options for perf record

On Fri, Mar 04, 2011 at 06:41:53PM +0900, Hitoshi Mitake wrote:
> On 03/01/11 23:55, Frederic Weisbecker wrote:
> >On Sat, Feb 26, 2011 at 02:10:30AM +0900, Hitoshi Mitake wrote:
> >>It seems that I was too preprocessed with the method and
> >>forgot the purpose...
> >>
> >>Maybe the things like simple lockstat visualizer or
> >>special diff between two lockstat snapshots are
> >>useful for the first looking at big picture.
> >>I feel that they have worth to write and test.
> >
> >Indeed they sound like good ideas. Being able to do a diff
> >on locks profiles would be useful to compare two changes on
> >the kernel.
> >
> 
> BTW, how do you think about the idea of exporting data in
> python (or other neutral) expression from procfs? I feel it is a
> good idea. Communicating with unified format between user space and
> kernel space will reduce lots of parsing overhead. Is this too
> aggressive or insane?

Well, I'm not sure about the goal of parsing that lockstat file.

lockstat is a global measurement since the boot. One of the point with
perf is that you can measure the same things than lockstat (and more)
on a delimited context and time slice: a process or a cpu for a given time.

So the right source is more on perf.data resulting in a precise measurement
than in a global /proc/, right?
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