From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755562Ab1BISW6 (ORCPT ); Wed, 9 Feb 2011 13:22:58 -0500 Received: from mx1.redhat.com ([209.132.183.28]:61317 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754958Ab1BISW5 (ORCPT ); Wed, 9 Feb 2011 13:22:57 -0500 From: Jeff Moyer To: David Ahern Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Paul Mackerras , Arnaldo Carvalho de Melo Subject: Re: perf on 2.6.38-rc4 wedges my box References: <4D52D31E.5010801@gmail.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Wed, 09 Feb 2011 13:22:37 -0500 In-Reply-To: <4D52D31E.5010801@gmail.com> (David Ahern's message of "Wed, 09 Feb 2011 10:47:10 -0700") Message-ID: User-Agent: Gnus/5.110011 (No Gnus v0.11) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Ahern writes: > Have you tried '-e cpu-clock' for S/W based profiling vs the default H/W > profiling? Add -v to see if the fallback to S/W is happening now. Thanks for the suggestion, David. I tried: # perf record -v ls Warning: ... trying to fall back to cpu-clock-ticks couldn't open /proc/-1/status couldn't open /proc/-1/maps [ls output] [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.008 MB perf.data (~363 samples) ] If I explicitly set '-e cpu-clock', then the output is the same, except that the warning is gone. What's up with the /proc/-1/*? Now, when running perf record -e cpu-clock on the aio-stress run, unsurprisingly, I get the same result: # perf record -e cpu-clock -v -- ./aio-stress -O -o 0 -r 4 -d 32 -b 16 /dev/sds couldn't open /proc/-1/status couldn't open /proc/-1/maps adding stage write starting with write file size 1024MB, record size 4KB, depth 32, ios per iteration 8 max io_submit 16, buffer alignment set to 4KB threads 1 files 1 contexts 1 context offset 2MB verification off adding file /dev/sds thread 0 and there it sits. In this case, however, I did not see the NOHZ warnings on the console, and this time the machine is still responding to ping, but nothing else. Cheers, Jeff