From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262550AbVCVIWi (ORCPT ); Tue, 22 Mar 2005 03:22:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262556AbVCVIWh (ORCPT ); Tue, 22 Mar 2005 03:22:37 -0500 Received: from mx2.elte.hu ([157.181.151.9]:64207 "EHLO mx2.elte.hu") by vger.kernel.org with ESMTP id S262550AbVCVIWc (ORCPT ); Tue, 22 Mar 2005 03:22:32 -0500 Date: Tue, 22 Mar 2005 09:22:22 +0100 From: Ingo Molnar To: Lee Revell Cc: linux-kernel , Andrew Morton , "Jack O'Quin" Subject: Re: Latency tests with 2.6.12-rc1 Message-ID: <20050322082222.GB9497@elte.hu> References: <1111204984.12740.22.camel@mindpipe> <20050319070810.GA20059@elte.hu> <1111218702.13039.5.camel@mindpipe> <1111269392.15042.12.camel@mindpipe> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1111269392.15042.12.camel@mindpipe> User-Agent: Mutt/1.4.1i 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 * Lee Revell wrote: > [...] Next I tried the same test but with JACK running. The longest > latency reported was only 200 usecs, and I did not get xruns. > > Then, right after I stopped JACK, the latency tracer shot up to 1645 > usecs. > > So there seems to be a bug in the latency tracer where the timer is > not being reset on reschedule. If an RT task like JACK is running, > the task does wakeup properly and the counter is reset. But if JACK > is not running then long latencies will be reported. hm, weird, and i have no solution for this yet. But i just found a related bug in the -RT patch in that it reverted a latency breaker in the ext3 path that your trace shows - affecting PREEMPT_DESKTOP. Could you try the 40-03 patch i just uploaded (assuming it's stable for you otherwise ...) and see whether you can still reproduce these latencies? (if yes then please also send me a full trace via private mail, or bzip -9 it in your public mail.) Ingo