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

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Date:	Mon, 7 May 2012 18:03:39 +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 17:15:18, Peter Zijlstra wrote:
> On Mon, 2012-05-07 at 16:47 +0200, Robert Richter wrote:
> > > Who again wasn't decoding anything in perf_event_attr:config* ?
> > 
> > attr:config is one of the ibs control msrs comparable with perfctr's
> > evntsel msr:
> > 
> >  MSRC001_1030 IBS Fetch Control Register (IbsFetchCtl)
> >  MSRC001_1033 IBS Execution Control Register (IbsOpCtl)
> 
> You missed reading a '*', even so:
> 
> > There are some options (randomisation, cycle/micro-op counting) but
> > usually it is null since the period is encoded in attr:period. But ibs
> > could be setup by an application using attr:config only which then
> > passes the value directly to the ctl msr. 
> 
> PMU_FORMAT_ATTR(IbsFetchMaxCnt, "config:0-15"   );
> PMU_FORMAT_ATTR(IbsFetchCnt,	"config:16-31"	);
> PMU_FORMAT_ATTR(IbsFetchVal,	"config:49"	);
> PMU_FORMAT_ATTR(IbsRandEn,	"config:57"	);
> 
> and
> 
> PMU_FORMAT_ATTR(IbsOpMaxCnt,	"config:0-15"	);
> PMU_FORMAT_ATTR(IbsOpVal,	"config:18"	);
> PMU_FORMAT_ATTR(IbsOpCntCtl,	"config:19"	); /* subject to ibs_caps */
> 
> Are the writable bitfields of those two MSRs resp.
> 
> This patch adds:
> 
> PMU_FORMAT_ATTR(IbsFilter0Idx,	"config1:0-7"	);
> PMU_FORMAT_ATTR(IbsFilter0Type,	"config1:12-15"	);
> PMU_FORMAT_ATTR(IbsFilter0Mask,	"config1:16-23"	);
> PMU_FORMAT_ATTR(IbsFilter0Match,"config1:24-31"	);
> PMU_FORMAT_ATTR(IbsFilter0Any,	"config1:16-31"	);
> 

Yes, let's take this format specification for config and drop kernel
side filtering in config[12].

Passing options like IbsRandEn was another open item. This is a nice
solution for this.

-Robert

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

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