From mboxrd@z Thu Jan 1 00:00:00 1970 From: Carsten Emde Subject: Re: Hard lockup with 2.6.24.7-rt26 on x86 Date: Tue, 03 Feb 2009 16:44:10 +0100 Message-ID: <4988664A.3080601@osadl.org> References: <37144.1233608136@vtxmail.ch> <20090203090052.6a4dc4de@torg> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: m.luescher@vtxmail.ch, linux-rt-users@vger.kernel.org, Thomas Gleixner , Steven Rostedt To: Clark Williams Return-path: Received: from toro.web-alm.net ([62.245.132.31]:55917 "EHLO toro.web-alm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752398AbZBCPvN (ORCPT ); Tue, 3 Feb 2009 10:51:13 -0500 In-Reply-To: <20090203090052.6a4dc4de@torg> Sender: linux-rt-users-owner@vger.kernel.org List-ID: Clark, >> On two different desktop PC (both Core 2 Duo) and on a notebook >> (Core Duo) the kernel (2.6.24.7-rt26, CONFIG_X86_32) locks up hard >> under a certain rt load. The failure can be reproduced reliably >> with the following command: >> sudo ./cyclictest -p99 -t10 -n -i250 > My guess would be that since you're running 10 threads on two > processors at the highest available priority, you're starving all the > hard IRQ threads (as well as soft irq and other kernel threads). > This is one of those power-tool moments where you can lock up the > system with the wrong workload/priority combination. Hmm, I would agree immediately, if the tasks were using all of the CPU power. But this is not the case. In the present case, running # cyclictest -p99 -t10 -n -i250 results in about 10% CPU load. So there is plenty of time in between to let the system respond. I can reproduce the problem here (2.6.24-rt, 2.6.26-rt, various configurations). The system does not crash every time when cyclictest is started, only once in about 5 trials or so. If it crashes, then it does so immediately after being started. Whenever cyclictest survives for several seconds, then it never crashes at a later time. I tend to believe that we have a bug here, not a regular behavior. Carsten.