Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756918Ab2ENPGg (ORCPT ); Mon, 14 May 2012 11:06:36 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:43091 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755780Ab2ENPGf (ORCPT ); Mon, 14 May 2012 11:06:35 -0400 Subject: Re: [GIT PULL 0/8] Annotation weekly ponies delivery From: Namhyung Kim To: Ingo Molnar Cc: Peter Zijlstra , Linus Torvalds , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, Arjan van de Ven , David Ahern , Frederic Weisbecker , Mike Galbraith , Paul Mackerras , Stephane Eranian , arnaldo.melo@gmail.com, Arnaldo Carvalho de Melo In-Reply-To: <20120514115551.GA6479@gmail.com> References: <1336852387-16322-1-git-send-email-acme@infradead.org> <1336994000.2443.24.camel@twins> <20120514115551.GA6479@gmail.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 15 May 2012 00:06:25 +0900 Message-ID: <1337007985.1552.5.camel@leonhard> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2298 Lines: 68 2012-05-14 (월), 13:55 +0200, Ingo Molnar: > * 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. > perf_evlist__config_attrs() has this: if (evlist->cpus->map[0] < 0) opts->no_inherit = true; meaning that per task profiling won't enable event inheritance. I don't know why it's needed though. -- Regards, Namhyung Kim -- 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/