linux-kernel - Re: [PATCH 1/2] perf tools: Add reference timestamp to perf header

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Message-ID: <20101213180548.GF1691@nowhere>
Date:	Mon, 13 Dec 2010 19:05:54 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	"David S. Ahern" <daahern@...co.com>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/2] perf tools: Add reference timestamp to perf header

On Mon, Dec 13, 2010 at 06:51:13PM +0100, Peter Zijlstra wrote:
> On Mon, 2010-12-13 at 15:43 -0200, Arnaldo Carvalho de Melo wrote:
> > Whatever, never introduced one, they are inserted, IIRC, in the
> > beggining of the stream, so I guess we can just do that sed and call
> > them headers and be done with it. 
> 
> There's the flush thing from Frederic, that's all over the place.
> 
> The easiest way to kill that is to go to separate data files now.
> writing to different files is better for contention anyway, we can grow
> a flusher-thread per buffer and let them write to their own file.

Right. We need to go there in the end anyway.
I had an old experiment of this some month ago:

git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
	perf/percpu

There is one writer per cpu and a (stupid) multiplexing at report time.
It was working. Just the sorting on report time was (stupidly) slow.

I should perhaps rebase that branch and try to make something with it.
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