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Date: Wed, 19 Aug 2009 14:56:13 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Arnaldo Carvalho de Melo <acme@redhat.com>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Mike Galbraith <efault@gmx.de>, linux-kernel@vger.kernel.org,
       stephane eranian <eranian@googlemail.com>
Subject: Re: [PATCH 4/4][RFC] perf_counter: Allow sharing of output channels
Message-ID: <20090819125613.GA30547@elte.hu>
References: <20090819091823.916851355@chello.nl> <20090819092023.980284148@chello.nl> <19083.61914.571806.395197@cargo.ozlabs.ibm.com>
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* Paul Mackerras <paulus@samba.org> wrote:

> Peter Zijlstra writes:
> 
> > Provide the ability to configure a counter to send its output 
> > to another (already existing) counter's output stream.
> 
> What sort of thing might this be useful for?

To share the output buffer - say you have a number of tracepoint 
counters enabled and want a single (coherent) stream of events 
without a post-processing sorting pass.

Right now each counter has to be opened, mmap-ed separately and 
then the result stuffed into the output file.

	Ingo