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Date: Fri, 10 Jul 2009 05:53:19 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>, Jason Baron <jbaron@redhat.com>,
       linux-kernel@vger.kernel.org, paulus@samba.org
Subject: Re: [PATCH 0/2] perf_counter: add tracepoint support
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References: <cover.1246912068.git.jbaron@redhat.com> <20090709031032.GA6412@nowhere> <1247126283.9777.318.camel@twins>
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* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

> On Thu, 2009-07-09 at 05:10 +0200, Frederic Weisbecker wrote:

> > (RFD parenthesis: why not using the one in kernel/trace for all 
> > perf events? Now that it is lockless, it would fit nicely 
> > inside: no fear about NMI context).
> 
> because that one doesn't have a single-buffer mode you can mmap().

Yeah, the ring-buffer code could certainly be abstracted out better 
to allow this. Once that is done it would allow us to do a couple of 
nice things: such as splice support (which could perhaps be faster 
than mmap for perf record) and the sampling of tracepoints would 
become a whole lot easier a well. But it's certainly not a trivial 
job!

	Ingo