From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267314AbUJIThF (ORCPT ); Sat, 9 Oct 2004 15:37:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267324AbUJIThF (ORCPT ); Sat, 9 Oct 2004 15:37:05 -0400 Received: from gonzo.webpack.hosteurope.de ([217.115.142.69]:21433 "EHLO gonzo.webpack.hosteurope.de") by vger.kernel.org with ESMTP id S267314AbUJIThA (ORCPT ); Sat, 9 Oct 2004 15:37:00 -0400 Date: Sat, 9 Oct 2004 21:38:17 +0000 From: stefan.eletzhofer@eletztrick.de To: linux-kernel Subject: Re: [ANNOUNCE] Linux 2.6 Real Time Kernel Message-ID: <20041009213817.GB25441@tier.local> Reply-To: stefan.eletzhofer@eletztrick.de Mail-Followup-To: stefan.eletzhofer@eletztrick.de, linux-kernel References: <41677E4D.1030403@mvista.com> <416822B7.5050206@opersys.com> <1097346628.1428.11.camel@krustophenia.net> <20041009212614.GA25441@tier.local> <1097350227.1428.41.camel@krustophenia.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1097350227.1428.41.camel@krustophenia.net> Organization: Eletztrick Computing User-Agent: Mutt/1.5.6i X-HE-MXrcvd: no Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Oct 09, 2004 at 03:30:27PM -0400, Lee Revell wrote: > On Sat, 2004-10-09 at 17:26, stefan.eletzhofer@eletztrick.de wrote: > > On Sat, Oct 09, 2004 at 02:30:28PM -0400, Lee Revell wrote: > > > On Sat, 2004-10-09 at 13:41, Karim Yaghmour wrote: > > > > Sven-Thorsten Dietrich wrote: > > > > > - Voluntary Preemption by Ingo Molnar > > > > > - IRQ thread patches by Scott Wood and Ingo Molnar > > > > > - BKL mutex patch by Ingo Molnar (with MV extensions) > > > > > - PMutex from Germany's Universitaet der Bundeswehr, Munich > > > > > - MontaVista mutex abstraction layer replacing spinlocks with mutexes > > > > > > > > To the best of my understanding, this still doesn't provide deterministic > > > > hard-real-time performance in Linux. > > > > > > Using only the VP+IRQ thread patch, I ran my RT app for 11 million > > > cycles yesterday, with a maximum delay of 190 usecs. How would this not > > > satisfy a 200 usec hard RT constraint? > > > > I think the keyword here is "deterministic", isn't it? > > Well, depends what you mean by deterministic. Some RT apps only require > an upper bound on response time. This is a form of determinism. Yes. But can you give that upper bound "a priori", that is w/o doing measurements with your application? Without that I think its impossible to get _guaranteed_ upper bounds, regardles of the application running. I think thats what "hard real-time" is all about. Stefan > > 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/ -- Stefan Eletzhofer InQuant Data GBR http://www.inquant.de +49 (0) 751 35 44 112 +49 (0) 171 23 24 529 (Mobil) +49 (0) 751 35 44 115 (FAX)