Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964901AbVJUIFE (ORCPT ); Fri, 21 Oct 2005 04:05:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964905AbVJUIFC (ORCPT ); Fri, 21 Oct 2005 04:05:02 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:4524 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S964901AbVJUIFA (ORCPT ); Fri, 21 Oct 2005 04:05:00 -0400 Date: Fri, 21 Oct 2005 10:05:04 +0200 From: Ingo Molnar To: Fernando Lopez-Lezcano Cc: William Weston , cc@ccrma.Stanford.EDU, linux-kernel@vger.kernel.org, Thomas Gleixner , david singleton , Steven Rostedt , Rui Nuno Capela , Mark Knecht Subject: Re: 2.6.14-rc4-rt7 Message-ID: <20051021080504.GA5088@elte.hu> References: <20051017160536.GA2107@elte.hu> <1129576885.4720.3.camel@cmn3.stanford.edu> <1129599029.10429.1.camel@cmn3.stanford.edu> <20051018072844.GB21915@elte.hu> <1129669474.5929.8.camel@cmn3.stanford.edu> <20051019111943.GA31410@elte.hu> <1129835571.14374.11.camel@cmn3.stanford.edu> <20051020191620.GA21367@elte.hu> <1129852531.5227.4.camel@cmn3.stanford.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1129852531.5227.4.camel@cmn3.stanford.edu> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=AWL autolearn=disabled SpamAssassin version=3.0.4 0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1237 Lines: 31 * Fernando Lopez-Lezcano wrote: > Found this on the logs: > > Oct 20 15:52:57 cmn3 kernel: BUG in hydrogen:4810, ktimer expired > short without user signal!: hm. This suggests that hydrogen executing schedule_ktimer() was waken up 45 microseconds too early, and most likely it was not woken up by the hres timer code (which should have done the wakeup 45 microseconds later anyway). I've added special hres-wakeup-debugging code to the scheduler in -rc5-rt2 to catch this particular scenario, you might want to give it a try. The new code is always enabled and it should pinpoint the precise place that does the wrong wakeup. You should see a new type of warning in your log: BUG: foo:1234 waking up bar:4321, expiring ktimer short without user signal! in shortly before the usual "BUG: ktimer expired short" message. Both messages will be triggered only once per bootup - but the condition itself likely occurs much more often on your box. Ingo - 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/