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

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Message-ID: <20120507155855.GJ18810@erda.amd.com>
Date:	Mon, 7 May 2012 17:58:55 +0200
From:	Robert Richter <robert.richter@....com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Ingo Molnar <mingo@...nel.org>,
	Stephane Eranian <eranian@...gle.com>,
	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 17:51:51, Peter Zijlstra wrote:
> On Mon, 2012-05-07 at 17:44 +0200, Robert Richter wrote:
> > On 07.05.12 15:03:02, Peter Zijlstra wrote:
> > > On Wed, 2012-05-02 at 20:26 +0200, Robert Richter wrote:
> > > > +enum ibs_filter_type {
> > > > +       IBS_NO_FILTER           = 0,
> > > > +       IBS_MATCH_FILTER        = 1,
> > > > +       IBS_ANY_SET_FILTER      = 2,
> > > > +       IBS_PSEUDO_EVENT        = 0x0F,
> > > > +};
> > > 
> > > I don't get how those pseudo events work, AFAIKT IBS_PSEUDO_EVENT causes
> > > one to loose all events since it does have a filter set but fails the
> > > filter and thus we skip the call to perf_event_overflow().
> > 
> > You periodically (fix clk cycles or number of micro-ops) trigger IBS
> > samples and afterwards analyses the samples for certain filter rules
> > (see rule description in pmu-ibs.c). 
> 
> But IBS_PSEUDO_EVENT will fail all filter test and you'll end up with
> exactly 0 samples. Still somewhat confused..

Ahh, got your question. This is a place holder for writing the pseudo
event id's (0xF000 mask) directly in config[12]. But this is not yet
implemented. And since we probably all prefer userland filtering we
just don't need this at all.

-Robert

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

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