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

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Date:	Mon, 07 Dec 2009 23:57:52 +0900 (JST)
From:	Hitoshi Mitake <mitake@....info.waseda.ac.jp>
To:	mingo@...e.hu
Cc:	fweisbec@...il.com, linux-kernel@...r.kernel.org,
	a.p.zijlstra@...llo.nl, paulus@...ba.org, tzanussi@...il.com,
	srostedt@...hat.com
Subject: Re: [PATCH 2/2] perf lock: New subcommand "lock" to perf for
 analyzing lock statistics

From: Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH 2/2] perf lock: New subcommand "lock" to perf for analyzing lock statistics
Date: Mon, 7 Dec 2009 08:27:52 +0100

> 
> * 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.

Thanks!

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

Yes of course. I didn't signed
because these were too experimental things for master branch.
But I can sign on these as experimental things on experimental branch.

> 
> 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.

Yeah, as I described in my reply to Frederic,
separating lockdep and lock events for perf lock
might be solution for performance problem. I'll try it.

Thanks
	Hitoshi
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