Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756143Ab2ENLz6 (ORCPT ); Mon, 14 May 2012 07:55:58 -0400 Received: from mail-we0-f174.google.com ([74.125.82.174]:57096 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755595Ab2ENLz4 (ORCPT ); Mon, 14 May 2012 07:55:56 -0400 Date: Mon, 14 May 2012 13:55:51 +0200 From: Ingo Molnar To: Peter Zijlstra Cc: Linus Torvalds , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, Arjan van de Ven , David Ahern , Frederic Weisbecker , Mike Galbraith , Namhyung Kim , Paul Mackerras , Stephane Eranian , arnaldo.melo@gmail.com, Arnaldo Carvalho de Melo Subject: Re: [GIT PULL 0/8] Annotation weekly ponies delivery Message-ID: <20120514115551.GA6479@gmail.com> References: <1336852387-16322-1-git-send-email-acme@infradead.org> <1336994000.2443.24.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1336994000.2443.24.camel@twins> 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: 1946 Lines: 56 * Peter Zijlstra wrote: > On Sat, 2012-05-12 at 13:40 -0700, Linus Torvalds wrote: > > The whole "-e cycles:pp" doesn't work any more. I don't get any nice > > PEBS information, I get the totally useless irq-based profiling. > > > > The difference for a "make -j" profile is quite stunning: > > > > Doing "perf record -f -e cycles:pp -F 20000 make -j" > > > > - my current git: > > > > [ perf record: Woken up 47 times to write data ] > > [ perf record: Captured and wrote 11.890 MB perf.data (~519462 samples) ] > > > > - with the above tree pulled into my current git tree (but compiling > > the same old tree): > > > > [ perf record: Woken up 1 times to write data ] > > [ perf record: Captured and wrote 0.031 MB perf.data (~1375 samples) ] > > The output simply suggests we're not getting enough samples > not that PEBS isn't working, in fact I can could reproduce > without using PEBS. > > This bisected to the below commit, the code has since been > changed again and all that evlist stuff gives me a head-ache. > Acme, Namhyung ? > > 55261f46702cec96911a81aacfb3cba13434d304 is the first bad commit > commit 55261f46702cec96911a81aacfb3cba13434d304 > Author: Namhyung Kim > Date: Mon May 7 14:08:59 2012 +0900 > > perf evlist: Fix creation of cpu map Another detail seems to be that the bug takes per-task-inherited profiling. Doing: perf record -a -e cycles:pp make -j64 bzImage produces the expected number of events. Without the '-a' the bug Linus found triggers. Similarly, 'perf top' does not trigger the bug - because it's using per CPU, not per task (inherited) profiling. Thanks, Ingo -- 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/