linux-kernel - Re: [PATCH] perf_events: improve DS/BTS/PEBS buffer allocation

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Message-ID: <20100913194258.GB28294@Krystal>
Date:	Mon, 13 Sep 2010 15:42:58 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Stephane Eranian <eranian@...gle.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	linux-kernel@...r.kernel.org, mingo@...e.hu, paulus@...ba.org,
	davem@...emloft.net, perfmon2-devel@...ts.sf.net,
	eranian@...il.com, robert.richter@....com,
	"markus.t.metzger" <markus.t.metzger@...el.com>
Subject: Re: [PATCH] perf_events: improve DS/BTS/PEBS buffer allocation

* Peter Zijlstra (peterz@...radead.org) wrote:
> On Mon, 2010-09-13 at 15:31 -0400, Mathieu Desnoyers wrote:
> > > Ok, so can we play the same trick you're playing with the sampling
> > > buffer, i.e., you use alloc_pages_node() for one page at a time, and
> > > then you stitch them on demand via SW?
> > 
> > Well, a thought is striking me: it sounds like you are re-doing YAORB (short
> > for Yet Another Ring Buffer, 
> 
> He's not.. the hardware needs a large (virtually) contiguous region to
> poke data into, we need to read it out from NMI context.

Ah ok, it's different then.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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