Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263287AbUJ2Lma (ORCPT ); Fri, 29 Oct 2004 07:42:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263284AbUJ2LjA (ORCPT ); Fri, 29 Oct 2004 07:39:00 -0400 Received: from mx1.elte.hu ([157.181.1.137]:17808 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S263268AbUJ2Lfo (ORCPT ); Fri, 29 Oct 2004 07:35:44 -0400 Date: Fri, 29 Oct 2004 13:36:52 +0200 From: Ingo Molnar To: Paul Davis Cc: Thomas Gleixner , LKML , Lee Revell , mark_h_johnson@raytheon.com, Bill Huey , Adam Heath , Florian Schmidt , Michal Schmidt , Fernando Pablo Lopez-Lezcano , Karsten Wiese , jackit-devel , Rui Nuno Capela Subject: Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4] Message-ID: <20041029113652.GC32204@elte.hu> References: <20041029111408.GA28259@elte.hu> <200410291126.i9TBQuFu002731@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200410291126.i9TBQuFu002731@localhost.localdomain> 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 Content-Length: 1318 Lines: 28 * Paul Davis wrote: > >my main suspicion is that either the main jackd thread itself calls the > >kernel where the kernel (unexpectedly for jackd) schedules away for > >whatever reason, or that the chain of wakeup in the audio path somehow > >gets violated (i.e. a kernel problem). There's one quick thing we could > > the "max delay" measurement isn't a reflection of the runtime activity > of jackd. its simply a measurement of the delay between when jackd > expected to be next woken from poll and when it actually was. > > as you noted, jackd generally goes back to sleep in poll typically a > long time before the next interrupt is expected. hence any delay in > the wakeup is between the interrupt handler and the scheduler getting > jackd's main thread back on the processor. i think. this brings up the next question: does the jackd measurement also timestamp the time when it calls poll() - hence detecting in-jackd processing delays? If yes, which value is this from Rui's stats? If not then it might make sense to add it. 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/