Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758459Ab2EOPZ2 (ORCPT ); Tue, 15 May 2012 11:25:28 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:44671 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753207Ab2EOPZ0 (ORCPT ); Tue, 15 May 2012 11:25:26 -0400 Message-ID: <4FB2755F.9020606@gmail.com> Date: Tue, 15 May 2012 09:25:19 -0600 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Peter Zijlstra , Arnaldo Carvalho de Melo CC: Linus Torvalds , Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: Perf events warning.. References: <1337034048.27020.137.camel@laptop> <1337078996.27694.26.camel@twins> In-Reply-To: <1337078996.27694.26.camel@twins> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1518 Lines: 34 On 5/15/12 4:49 AM, Peter Zijlstra wrote: > On Mon, 2012-05-14 at 15:25 -0700, Linus Torvalds wrote: >> On Mon, May 14, 2012 at 3:20 PM, Peter Zijlstra wrote: >>> >>> So far I can't make any of the things I came up stick. You ran something >>> simple like: 'perf record -e cycles:pp -F 20000 make test' ? Or did you >>> do something more interesting? >> >> It was not much more complex than that. >> >> It did use "make -j64 test" to make the load a *bit* more interesting >> (and go noticeably faster), but other than that you got it. > > OK, that limits the scope of crazy scenarios I have to consider, still > no immediate clue though.. > > I think I've found a possible race, but I can't make it work with that > workload. I've also let your workload run for 2+ hours in trying to > reproduce, but no luck, it must be a very narrow window indeed. > > I'll keep prodding at it.. Perhaps it is specific to processor generation? Yesterday I noted that perf-stat -g trips a WARNING only on Nehalem. Westmere works fine - perf-stat -g generates output and no warning is triggered. Arnaldo is using Sandy Bridge - though it's not clear if his success (3.4.0-rc3 on server named sandy) or fail (3.4.0-rc4-uprobes on felicio) was on a SNB. David -- 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/