linux-kernel - Re: [PATCH 0/9] perf: Adding better precise

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Date:	Thu, 9 May 2013 17:20:22 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Namhyung Kim <namhyung@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Andi Kleen <ak@...ux.intel.com>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 0/9] perf: Adding better precise_ip field handling

On Thu, May 09, 2013 at 05:07:44PM +0200, Peter Zijlstra wrote:
> On Thu, May 09, 2013 at 03:32:15PM +0200, Jiri Olsa wrote:
> > hi,
> > adding sysfs attribute to specify the maximum allowed value
> > for perf_event_attr::precise_ip field.
> > 
> > Adding functionality for simple 'p' modifier and 'precise' term
> > to get the maximum allowed value for perf_event_attr::precise_ip
> > field.
> > 
> 
> You've seem to lost the part explaining why we want this.. :-)

well, initially it was an answer when we broke precise event
monitoring in kernel so I wrote automated test for it (patches 1,2,3)
https://lkml.org/lkml/2012/12/12/561

having maximum precise enabled with just single 'p' seemed
like good idea

next step would be to enable precise automatically for 'cycles'
(when PEBS is working) asked for by Ingo
http://marc.info/?l=linux-kernel&m=135929050803963&w=2

jirka
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