Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261892AbUKHPxl (ORCPT ); Mon, 8 Nov 2004 10:53:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261903AbUKHPxl (ORCPT ); Mon, 8 Nov 2004 10:53:41 -0500 Received: from mx1.elte.hu ([157.181.1.137]:32402 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S261892AbUKHOkl (ORCPT ); Mon, 8 Nov 2004 09:40:41 -0500 Date: Mon, 8 Nov 2004 16:42:46 +0100 From: Ingo Molnar To: Esben Nielsen Cc: Bill Huey , Scott Wood , john cooper , Mark_H_Johnson@raytheon.com, Karsten Wiese , Adam Heath , "K.R. Foley" , linux-kernel@vger.kernel.org, Florian Schmidt , Fernando Pablo Lopez-Lezcano , Lee Revell , Rui Nuno Capela , Thomas Gleixner , Michal Schmidt Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc1-mm2-V0.7.1 Message-ID: <20041108154246.GA32212@elte.hu> References: <20041105223610.GA3756@nietzsche.lynx.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: 929 Lines: 21 * Esben Nielsen wrote: > On a SMP system you don't have these nice properties. You always have > to take into account that N processes are really running at the same > time. not necessarily. In theory we could introduce the notion of "hyper-high-priority tasks" (e.g. SCHED_HYPER_FIFO), which tasks not only get preempted on one CPU immediately, but cause the kernel to stop and loop on all other CPUs as well. That way the same 'nice' properties of UP kernels get carried over to the SMP system as well, at the cost of serializing all execution while the hyper-high-prio task is running. Once the task stops running, the other CPUs can continue as well. 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/