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Date: Sat, 21 Mar 2009 17:26:30 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>,
       Thomas Gleixner <tglx@linutronix.de>,
       =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>,
       Arjan van de Ven <arjan@infradead.org>,
       Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH][GIT PULL] tracing: add function profiler
Message-ID: <20090321162630.GE11183@elte.hu>
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* Steven Rostedt <rostedt@goodmis.org> wrote:

> > If you want exact function count profiling we could try to do 
> > something perf counter based, eg. stick a software counter in 
> > the mcount thingy.
> 
> I'd like to get the function graph version working, in order to 
> calculate the times spent in each funtion, then I can see how we 
> can (if possible) convert it over to perf counters. :-/

the perf counters angle is definitely worth pursuing (for 
completeness of the scheme Peter is working on), but please lets not 
throw the baby out with the bath water: in-kernel histogram 
collection has real value.

It's _much_ faster than any user-space counter-part, especially for 
such things as branch tracing or function tracing.

	Ingo