Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752929Ab3EJJlg (ORCPT ); Fri, 10 May 2013 05:41:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10626 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751576Ab3EJJlf (ORCPT ); Fri, 10 May 2013 05:41:35 -0400 Date: Fri, 10 May 2013 11:40:53 +0200 From: Jiri Olsa To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Corey Ashford , Frederic Weisbecker , Ingo Molnar , Namhyung Kim , Paul Mackerras , Arnaldo Carvalho de Melo , Andi Kleen , David Ahern , Stephane Eranian Subject: Re: [PATCH 0/9] perf: Adding better precise_ip field handling Message-ID: <20130510094053.GF1040@krava.brq.redhat.com> References: <1368106344-23383-1-git-send-email-jolsa@redhat.com> <20130509150744.GB3039@dyad.programming.kicks-ass.net> <20130509152022.GD1628@krava.brq.redhat.com> <20130510092741.GE3039@dyad.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130510092741.GE3039@dyad.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2128 Lines: 56 On Fri, May 10, 2013 at 11:27:41AM +0200, Peter Zijlstra wrote: > On Thu, May 09, 2013 at 05:20:22PM +0200, Jiri Olsa wrote: > > 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 > > But those don't rely on the max thing right? nope, but I need a automated way to find out if PEBS is supported in system > > > having maximum precise enabled with just single 'p' seemed > > like good idea > > Doesn't seem like to me; that takes away the possibility to use less. hm, we could have another modifier to get system precise value 'P' maybe.. and keep the 'p' logic > > > 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 > > Hurm.. I'm of two minds there. As Stephane has been pointing out for ages, > cycles behaves significantly different between regular and PEBS events for some > cases. > > Also, you really don't need the max_precise for that either. At worst you'll > have a number of unsuccessful event creations. so you mean just detect that by opening events with increasing precise and see how far we could get.. could be I guess, though the 'precise' sysfs attribute seems more fit to me thanks, jirka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/