From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263117AbTJJS1N (ORCPT ); Fri, 10 Oct 2003 14:27:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263118AbTJJS1M (ORCPT ); Fri, 10 Oct 2003 14:27:12 -0400 Received: from holomorphy.com ([66.224.33.161]:13698 "EHLO holomorphy") by vger.kernel.org with ESMTP id S263117AbTJJS1K (ORCPT ); Fri, 10 Oct 2003 14:27:10 -0400 Date: Fri, 10 Oct 2003 11:29:09 -0700 From: William Lee Irwin III To: Tim Hockin 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: <20031010182909.GG727@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Tim Hockin , 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> <20031010180320.GA1995@hockin.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20031010180320.GA1995@hockin.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 On Fri, Oct 10, 2003 at 07:47:23AM -0700, 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. On Fri, Oct 10, 2003 at 11:03:20AM -0700, Tim Hockin wrote: > I've got a patch against RedHat's 2.4.x kernel with some version of O(1) > scheduler that migrates all processes off a CPU and makes it ineleigible to > run new tasks. When the syscall returns, it is safe to remove the CPU. > Processes that are running or sleeping and can be migrated elsewhere are > migrated. Running processes that have set_cpus_allowed to ONLY the > processor in question are marked TASK_UNRUNNABLE and moved off the runqueue. > Sleeping processes that have set_cpus_allowed to ONLY the processor in > question are left unmolested until they wake up, at which point they will be > marked UNRUNNABLE. > It was done to allow software to bring CPUs on/offline, but it should work > for this. IRQs not done yet, either. I think there is some generalized cpu hotplug stuff that's gone in that direction already, though I don't know any details. The bits about non- cooperative offlining were very interesting to hear, though. -- wli