Subject: Re: [PATCH 00/12] perf lock: New subcommand "perf lock", for
 analyzing lock statistics
From: Peter Zijlstra <peterz@infradead.org>
To: Jason Baron <jbaron@redhat.com>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>, Ingo Molnar <mingo@elte.hu>,
       linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
       Tom Zanussi <tzanussi@gmail.com>, Steven Rostedt <srostedt@redhat.com>,
       Thomas Gleixner <tglx@linutronix.de>,
       Greg Kroah-Hartman <gregkh@suse.de>
In-Reply-To: <20100122164248.GA2651@redhat.com>
References: <1264167553-6510-1-git-send-email-mitake@dcl.info.waseda.ac.jp>
	 <20100122164248.GA2651@redhat.com>
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Date: Fri, 22 Jan 2010 17:48:29 +0100
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On Fri, 2010-01-22 at 11:42 -0500, Jason Baron wrote:
> On Fri, Jan 22, 2010 at 10:39:01PM +0900, Hitoshi Mitake wrote:
> > Adding new subcommand "perf lock" to perf.
> > 
> 
> looks like a really intresting patch! Does this patch mean that we can
> potentially remove CONFIG_LOCK_STAT, now that the functionality is
> available via 'perf'? Another desire for me has been to able to run
> lockstat on production box. This has not been possible before without
> incurring the performance penalty of lockdep. however, with 'perf' tools
> ability to be turned on an off, perhaps there is (or we can build) a
> mode for lockdep that is lower overhead for this usecase?

boot with: prove_locking=0

This patch still needs all the hooks and bits from lockdep, no way you
want all that in a prodction kernel.

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