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Date: Sat, 27 Sep 2008 19:47:56 +0200
From: Ingo Molnar <mingo@elte.hu>
To: =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
Cc: Pekka Paalanen <pq@iki.fi>, linux-kernel@vger.kernel.org,
       Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [Patch -tip 3/3] Tracing/ftrace: Don't consume entries
	unhandled by mmiotrace
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References: <48DB8408.7080408@gmail.com> <20080925173435.5f525557@daedalus.pq.iki.fi> <c62985530809250744t3ce0011ajebd8343eb748cf24@mail.gmail.com> <20080925183608.283babfb@daedalus.pq.iki.fi> <c62985530809250913q227a5876k19b1b0ec591ad3cd@mail.gmail.com>
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* Frédéric Weisbecker <fweisbec@gmail.com> wrote:

> 2008/9/25 Pekka Paalanen <pq@iki.fi>:
> > We can (must) return to this if/when multiple tracers are allowed
> > to be active simultaneously. But in the current situation, I do not
> > see a way to trace more than one thing, but I haven't really looked
> > into the other tracers.
> 
> You can enable another tracer simultaneously. I never tried it but you 
> can launch one from debugfs and another from kernel code for example. 
> The new boot tracer will have to launch the sched_switch tracer.

hm, right now i can see a lot of problems with that approach - the 
buffers are partly per tracer and partly global.

the new trace-ringbuffer design Steve is working on would abstract away 
this complication - then we could make tracers truly independent 
entities.

	Ingo