From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262909AbVFVIbw (ORCPT ); Wed, 22 Jun 2005 04:31:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262932AbVFVI0n (ORCPT ); Wed, 22 Jun 2005 04:26:43 -0400 Received: from mx1.elte.hu ([157.181.1.137]:39130 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S262934AbVFVIZz (ORCPT ); Wed, 22 Jun 2005 04:25:55 -0400 Date: Wed, 22 Jun 2005 10:24:50 +0200 From: Ingo Molnar To: William Weston Cc: "K.R. Foley" , linux-kernel@vger.kernel.org, "Eugeny S. Mints" , Daniel Walker Subject: Re: [patch] Real-Time Preemption, -RT-2.6.12-rc6-V0.7.48-00 Message-ID: <20050622082450.GA19957@elte.hu> References: <20050608112801.GA31084@elte.hu> <42B0F72D.5040405@cybsft.com> <20050616072935.GB19772@elte.hu> <42B160F5.9060208@cybsft.com> <20050616173247.GA32552@elte.hu> <20050621131249.GB22691@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * William Weston wrote: > Attached are two typical traces and the .config from my Xeon/HT box, > currently running -50-06 with a normal desktop workload (X, wmaker, > ten dockapps, several xterms, and firefox). the second trace seems to be a cross-CPU wakeup bug. It's not completely clear from the trace what happened - but we measured the latency of a task (wmcube-3191), where the wakeup happened on CPU#0 and wmcube-3191 was queued to CPU#1 which was idle at that time. The bug is that it wasnt until timestamp 306us that this actually happened - and CPU#1 was just idling around in default_idle() for no good reason. CPU#1 should have run wmcube-3191 at around timestamp 13us. I've uploaded the -50-07 kernel which will put some more info into the traces - could you try to repeat the measurement and get similar latencies? As i guess you already found out that you can always reset the measurement to get a new set of traces, via: echo 0 > /proc/sys/kernel/preempt_max_latency (it's not a problem if you send me multiple latency traces, i'll figure out which is the most useful one.) Ingo