Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261577AbUJaMNf (ORCPT ); Sun, 31 Oct 2004 07:13:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261594AbUJaMMT (ORCPT ); Sun, 31 Oct 2004 07:12:19 -0500 Received: from mustang.oldcity.dca.net ([216.158.38.3]:43685 "HELO mustang.oldcity.dca.net") by vger.kernel.org with SMTP id S261565AbUJaMKD (ORCPT ); Sun, 31 Oct 2004 07:10:03 -0500 Subject: Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4] From: Lee Revell To: Florian Schmidt Cc: Ingo Molnar , Paul Davis , Thomas Gleixner , LKML , mark_h_johnson@raytheon.com, Bill Huey , Adam Heath , Michal Schmidt , Fernando Pablo Lopez-Lezcano , Karsten Wiese , jackit-devel , Rui Nuno Capela In-Reply-To: <20041031110039.4575e49c@mango.fruits.de> References: <20041029172243.GA19630@elte.hu> <20041029203619.37b54cba@mango.fruits.de> <20041029204220.GA6727@elte.hu> <20041029233117.6d29c383@mango.fruits.de> <20041029212545.GA13199@elte.hu> <1099086166.1468.4.camel@krustophenia.net> <20041029214602.GA15605@elte.hu> <1099091566.1461.8.camel@krustophenia.net> <20041030115808.GA29692@elte.hu> <1099158570.1972.5.camel@krustophenia.net> <20041030191725.GA29747@elte.hu> <20041030214738.1918ea1d@mango.fruits.de> <1099165925.1972.22.camel@krustophenia.net> <20041030221548.5e82fad5@mango.fruits.de> <1099167996.1434.4.camel@krustophenia.net> <20041030231358.6f1eeeac@mango.fruits.de> <1099189225.1754.1.camel@krustophenia.net> <20041031110039.4575e49c@mango.fruits.de> Content-Type: text/plain Date: Sun, 31 Oct 2004 07:09:57 -0500 Message-Id: <1099224598.1459.28.camel@krustophenia.net> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1318 Lines: 30 On Sun, 2004-10-31 at 11:00 +0100, Florian Schmidt wrote: > thanks for the patch (it has a little problem, since it uses prio 99 which > is always equal or greater than the rtc thread prio. i changed it in my > local version to accept a parameter). OK good idea. As in the JACK case, the relative priorities of the RTC irq thread and the test program should not matter as these two should never contend - something is seriously wrong if both are ever runnable at the same time. Actually this raises an interesting point. Maybe all IRQ threads should get the same RT priority by default, so we get FIFO scheduling among IRQ threads. It seems like this would make it harder for IRQ threads to starve each other. Then we only have to elevate the priority of the IRQ thread(s) we are interested in. Another idea is to allow SCHED_FIFO processes of equal priority to preempt one another on a LIFO basis. Wouldn't this be very close to the traditional Linux interrupt model, where interrupts can interrupt each other and we handle the most recent interrupt first? Lee - 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/