Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263520AbUJ2WZD (ORCPT ); Fri, 29 Oct 2004 18:25:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263497AbUJ2WX3 (ORCPT ); Fri, 29 Oct 2004 18:23:29 -0400 Received: from out011pub.verizon.net ([206.46.170.135]:25001 "EHLO out011.verizon.net") by vger.kernel.org with ESMTP id S263581AbUJ2UwB (ORCPT ); Fri, 29 Oct 2004 16:52:01 -0400 Message-Id: <200410292051.i9TKptOi007283@localhost.localdomain> To: Ingo Molnar cc: Thomas Gleixner , LKML , Bill Huey , Adam Heath , Michal Schmidt , Karsten Wiese , jackit-devel Subject: Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4] In-reply-to: Your message of "Fri, 29 Oct 2004 22:33:20 +0200." <20041029203320.GC5186@elte.hu> Date: Fri, 29 Oct 2004 16:51:55 -0400 From: Paul Davis X-Authentication-Info: Submitted using SMTP AUTH at out011.verizon.net from [141.151.88.122] at Fri, 29 Oct 2004 15:51:56 -0500 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1332 Lines: 34 [ I trimmed the CC: line because several people there are on jackit-devel. ] >> compiles and boots fine. no observable change in xrun behaviour though. > >ok, so there's something else going on as well - or i missed an ioctl. i really don't think the ioctl's are relevant. consider what will happen if jackd does make a system call that causes a major delay (say, because of the BKL). we will get an xrun, yes, but this will cause jackd to stop the audio interface and restart. max_delay is not affected by this behaviour. as far as i can tell, the number reported by max_delay entirely (or almost entirely) represents problems in kernel scheduling, specifically with a combination of: a) handling the audio interface interrupt in time. b) marking the relevant jackd thread runnable c) context switching back to the relevant jackd thread things that jackd does once its running do not, it appear to me, have any impact on max_delay, which is based on the simple observation: "i was just woken, i expect to be awakened again in N usecs or less. --p - 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/