From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755461Ab1BIRie (ORCPT ); Wed, 9 Feb 2011 12:38:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:55322 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755130Ab1BIRic (ORCPT ); Wed, 9 Feb 2011 12:38:32 -0500 From: Jeff Moyer To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Ingo Molnar , Paul Mackerras , Arnaldo Carvalho de Melo Subject: perf on 2.6.38-rc4 wedges my box 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 12:38:10 -0500 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 Hi, I'm trying out willy's ata_ram driver[1], and in so doing have managed to wedge my box while using perf record on an aio-stress run: [root@metallica ~]# modprobe ata_ram capacity=2097152 preallocate=1 [root@metallica ~]# ./aio-stress -O -o 0 -r 4 -d 32 -b 16 /dev/sds 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 write on /dev/sds (621.30 MB/s) 1024.00 MB in 1.65s thread 0 write totals (621.27 MB/s) 1024.00 MB in 1.65s [root@metallica ~]# perf record -- ./aio-stress -O -o 0 -r 4 -d 32 -b 16 /dev/sds 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. On the console, I see: NOHZ: local_softirq_pending 100 NOHZ: local_softirq_pending 100 NOHZ: local_softirq_pending 100 NOHZ: local_softirq_pending 100 NOHZ: local_softirq_pending 100 The number of messages varies, but this is the most I've seen (it doesn't keep repeating). At this point, the machine does not respond to pings. As I don't have physical access at the moment, I can't try alt-sysrq, but might be able to do that tomorrow. It's probably worth noting that I've witnessed similar behavior with real devices, so it's not just the ata_ram driver. Any ideas on how to track this down? Thanks! Jeff [1] http://git.kernel.org/?p=linux/kernel/git/willy/misc.git;a=shortlog;h=refs/heads/ata-ram