linux-kernel - RE: [patch, resend] x86, perf_counter, bts: optimize BTS overflow handling

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Date:	Tue, 15 Sep 2009 13:25:15 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	"Metzger, Markus T" <markus.t.metzger@...el.com>
Cc:	"mingo@...e.hu" <mingo@...e.hu>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"hpa@...or.com" <hpa@...or.com>,
	"markus.t.metzger@...il.com" <markus.t.metzger@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [patch, resend] x86, perf_counter, bts: optimize BTS overflow
 handling

On Tue, 2009-09-15 at 12:18 +0100, Metzger, Markus T wrote:

> >> Restructure perf_counter sampling into sample creation and sample
> >> output.
> >> Prepare a single reference sample for BTS sampling and update the from
> >> and to address fields when draining the BTS buffer.
> >> Drain the entire BTS buffer between a single perf_output_begin() /
> >> perf_output_end() pair.
> >
> >Generally looks very nice, one thing though, why did you take regs out
> >of perf_sample_data, now you get to pass around one extra param..
> 
> 
> That is to make perf_sample_data describe the sample directly.
> 
> The regs are used to create the sample; they're not needed once
> the sample has been created.

True, but I'd have been lazy and not added that extra parameter all over
the place, but sure ;-)

This is now fast enough to BTS trace the kernel too?


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