linux-kernel - Re: [PATCH 2/2] perf lock: New subcommand "lock" to perf for analyzing lock statistics

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Date:	Mon, 7 Dec 2009 08:27:52 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Hitoshi Mitake <mitake@....info.waseda.ac.jp>,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Tom Zanussi <tzanussi@...il.com>,
	Steven Rostedt <srostedt@...hat.com>
Subject: Re: [PATCH 2/2] perf lock: New subcommand "lock" to perf for
 analyzing lock statistics

* Frederic Weisbecker <fweisbec@...il.com> wrote:

> On Mon, Dec 07, 2009 at 12:34:44PM +0900, Hitoshi Mitake wrote:
> > This patch adds new subcommand "lock" to perf for analyzing lock usage statistics.
> > Current perf lock is very primitive. This cannot provide the minimum functions.
> > Of course I continue to working on this.
> > But too big patch is not good thing for you, so I post this.
> 
> Oh great!
> Yeah, the work can be done incrementally.
>
[...]
>
> 
> Very nice and promising!
> 
> I can't wait to try it.

ok, to ease testing i've created a new (and not yet permanent) topic 
tree for it to track this new perf feature: tip:perf/lock and pushed it 
out.

Note: because it's not yet in a final form i have not merged it into 
tip:master yet - when you are working on these bits you need to do this 
manually via:

  git merge tip/perf/lock

Also, we might need to rebase this branch as it's WIP, so the commit IDs 
are not permanent yet. But i thought it would be easier to do deltas on 
this basis.

Hitoshi-san, the patches did not have a Signed-off-by line from you, can 
i add them for you?

Also, i agree that the performance aspect is probably the most pressing 
issue. Note that 'perf bench sched messaging' is very locking intense so 
a 10x slowdown is not entirely unexpected - we still ought to optimize 
it all some more. 'perf lock' is an excellent testcase for this in any 
case.

Thanks,

	Ingo
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