Date: Fri, 13 Nov 2009 09:17:22 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: a.p.zijlstra@chello.nl, tglx@linutronix.de, fweisbec@gmail.com,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH][RFC] Measuring term of acquiring spinlock
Message-ID: <20091113081722.GA14009@elte.hu>
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 <20091112073909.GB31719@elte.hu>
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* Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp> wrote:

> From: Ingo Molnar <mingo@elte.hu>
> Subject: Re: [PATCH][RFC] Measuring term of acquiring spinlock
> Date: Thu, 12 Nov 2009 08:39:09 +0100
> 
> > 
> > * Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp> wrote:
> > 
> > > * Description
> > > 
> > > This patch makes the file spinlock_stats on top of the debugfs.
> > > When user reads this file, some statistical data related to
> > > spinlocks are printed.
> > 
> > hm, are you aware of the lockstat tracepoints? They do something 
> > like this - and it utilizes perf events to report these events. See 
> > include/trace/events/lockdep.h. Needs CONFIG_LOCK_STAT enabled.
> >
> 
> Wow, I didn't know that. I'll try it.

Btw., i think we should rename that tracepoint category from 'lockdep' 
to 'lock'. It's possible to enable them without CONFIG_PROVE_LOCKING, 
and they arent high-overhead in that case.

	Ingo
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