linux-kernel - Re: [PATCH 4/7] perf/x86-ibs: Add support for IBS pseudo events

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Message-ID: <20120507155216.GI18810@erda.amd.com>
Date:	Mon, 7 May 2012 17:52:16 +0200
From:	Robert Richter <robert.richter@....com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Stephane Eranian <eranian@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/7] perf/x86-ibs: Add support for IBS pseudo events

On 07.05.12 17:29:17, Peter Zijlstra wrote:
> On Mon, 2012-05-07 at 17:21 +0200, Stephane Eranian wrote:
> > There is something I don't quite understand with those pseudo-events.
> > Is it the case that by construction, it means you can only measure
> > on pseudo-event at a time? Supposed I want to look at cache-misses.
> > For each miss, I'd like to know where it missed, any TLB impacts. All
> > of that in one run with no multiplexing. Can I do this with your
> > pseudo-events?
> > 
> Not from how I read the patch, a pseudo event will count as a full event
> and since the IBS things only have a single thing its full.
> 
> If you want multiple of these you'd have to get the raw stream and demux
> in userspace.

As said in my previous mail, this is a drawback. And as with
precise-rip it is better to implement this in userland.

The question here is how to implement it. You need the event option
string (-e) not only to setup the syscall but also for userspace
post-processing. Any hint for something similar already done in perf?

Thanks,

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center

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