From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262941AbTJJPTa (ORCPT ); Fri, 10 Oct 2003 11:19:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262942AbTJJPTa (ORCPT ); Fri, 10 Oct 2003 11:19:30 -0400 Received: from holomorphy.com ([66.224.33.161]:22145 "EHLO holomorphy") by vger.kernel.org with ESMTP id S262941AbTJJPT3 (ORCPT ); Fri, 10 Oct 2003 11:19:29 -0400 Date: Fri, 10 Oct 2003 08:21:20 -0700 From: William Lee Irwin III To: Jamie Lokier Cc: G?bor L?n?rt , Stuart Longland , Stephan von Krawczynski , Fabian.Frederick@prov-liege.be, linux-kernel@vger.kernel.org Subject: Re: 2.7 thoughts Message-ID: <20031010152120.GE727@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Jamie Lokier , G?bor L?n?rt , Stuart Longland , Stephan von Krawczynski , Fabian.Frederick@prov-liege.be, linux-kernel@vger.kernel.org References: <20031009115809.GE8370@vega.digitel2002.hu> <20031009165723.43ae9cb5.skraw@ithnet.com> <3F864F82.4050509@longlandclan.hopto.org> <20031010125137.4080a13b.skraw@ithnet.com> <3F86BD0E.4060607@longlandclan.hopto.org> <20031010143529.GT5112@vega.digitel2002.hu> <20031010144723.GC727@holomorphy.com> <20031010151231.GD28795@mail.shareable.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20031010151231.GD28795@mail.shareable.org> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org William Lee Irwin III wrote: >> You need at least enough warning to get out of critical sections (e.g. >> holding a spinlock) and dump registers out to memory. i.e. as long as it >> takes to schedule out whatever's currently running on the thing. >> ... and unless you want to start enforcing realtime bounds, the answer >> to "how long do you have to give the kernel to do it?" is "forever". >> In practice, it won't take forever, but no finite time is enforcible. On Fri, Oct 10, 2003 at 04:12:31PM +0100, Jamie Lokier wrote: > You can create a very peculiar scheduling state to make even > spinlocked sections multi-task, so the CPU can be released in a finite > time and quickly - about as quickly as taking an NMI and broadcasting > the critical IPIs to tell other CPUs to take over. > The peculiar state is restored to normal as soon as the number > of concurrent critical sections no longer exceeds the number of real CPUs. DOH. Okay, that would do it. -- wli