From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753272Ab2GWCh4 (ORCPT ); Sun, 22 Jul 2012 22:37:56 -0400 Received: from e23smtp06.au.ibm.com ([202.81.31.148]:38417 "EHLO e23smtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753086Ab2GWChz (ORCPT ); Sun, 22 Jul 2012 22:37:55 -0400 Message-ID: <500CB8F6.3000208@linux.vnet.ibm.com> Date: Mon, 23 Jul 2012 10:37:42 +0800 From: Michael Wang User-Agent: Mozilla/5.0 (X11; Linux i686; rv:13.0) Gecko/20120615 Thunderbird/13.0.1 MIME-Version: 1.0 To: Mike Galbraith CC: LKML , "paulmck@linux.vnet.ibm.com" , mmokrejs@fold.natur.cuni.cz, dan.carpenter@oracle.com Subject: Re: [QUESTION ON BUG] the rcu stall issue could not be reproduced References: <5008CBD4.6070907@linux.vnet.ibm.com> <1342767624.7432.54.camel@marge.simpson.net> <5009170E.1080807@linux.vnet.ibm.com> <1342775305.7432.76.camel@marge.simpson.net> In-Reply-To: <1342775305.7432.76.camel@marge.simpson.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit x-cbid: 12072302-7014-0000-0000-0000019A518E Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/20/2012 05:08 PM, Mike Galbraith wrote: > On Fri, 2012-07-20 at 16:30 +0800, Michael Wang wrote: >> On 07/20/2012 03:00 PM, Mike Galbraith wrote: >>> On Fri, 2012-07-20 at 11:09 +0800, Michael Wang wrote: >>>> Hi, Mike, Martin, Dan >>>> >>>> I'm currently taking an eye on the rcu stall issue which was reported by >>>> you in the mail: >>>> >>>> rcu: endless stalls >>>> From: Mike Galbraith >>>> linux-3.4-rc7: rcu_sched self-detected stall on CPU >>>> From: Martin Mokrejs >>>> RCU stalls in linux-next >>>> From: Dan Carpenter >>>> >>>> I try to reproduce the issue on my X86 server with 12 cpu >>> >>> The 'endless stalls' box was 341.33333 times larger. Dunno if you can >>> even set a serial port slow enough to approximate all cores trying to >>> gripe through a single pinhole simultaneously. >> >> Hi, Mike >> >> Thanks for your reply. >> >> So you mean this issue is still existing on you box and you can see it >> without doing any special things? > > It's not my box (thank god). It was initially triggered by tasks > exiting simultaneously on all cores. They jammed up, endless stall > followed. > >> I just want to try to reproduce it but it's impossible for me to get >> some hardware as yours... >> >> So is there any idea on how to reproduce it on normal hardware? > > No, AFAIK this problem is restricted to size XXL boxen, with all the > joys that come along with having way too many CPUs. I see, thanks for your info, looks like it's hard to reproduce on normal servers like mine... Regards, Michael Wang > > -Mike >