Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265163AbUATHXW (ORCPT ); Tue, 20 Jan 2004 02:23:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265168AbUATHXW (ORCPT ); Tue, 20 Jan 2004 02:23:22 -0500 Received: from mail-10.iinet.net.au ([203.59.3.42]:7112 "HELO mail.iinet.net.au") by vger.kernel.org with SMTP id S265163AbUATHXU (ORCPT ); Tue, 20 Jan 2004 02:23:20 -0500 Message-ID: <400CD4B5.6020507@cyberone.com.au> Date: Tue, 20 Jan 2004 18:11:49 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030827 Debian/1.4-3 X-Accept-Language: en MIME-Version: 1.0 To: Tim Hockin CC: Rusty Russell , vatsa@in.ibm.com, linux-kernel@vger.kernel.org, torvalds@osdl.org, akpm@osdl.org, rml@tech9.net Subject: Re: CPU Hotplug: Hotplug Script And SIGPWR References: <20040116174446.A2820@in.ibm.com> <20040120060027.91CC717DE5@ozlabs.au.ibm.com> <20040120063316.GA9736@hockin.org> <400CCE2F.2060502@cyberone.com.au> <20040120065207.GA10993@hockin.org> In-Reply-To: <20040120065207.GA10993@hockin.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1355 Lines: 35 Tim Hockin wrote: >On Tue, Jan 20, 2004 at 05:43:59PM +1100, Nick Piggin wrote: > >>>I think the sanest thing for a CPU removal is to migrate everything off the >>>processor in question, move unrunnable tasks into TASK_UNRUNNABLE state, >>>then notify /sbin/hotplug. The hotplug script can then find and handle the >>>unrunnable tasks. No SIGPWR grossness needed. >>> >>>Code against 2.4 at http://www.hockin.org/~thockin/procstate - it was >>>heavily tested and I *think* it is all correct (for that kernel snapshot). >>> >>Seems less robust and more ad hoc than SIGPWR, however. >> > >Disagree. SIGPWR will kill any process that doesn't catch it. That's >policy. It seems more robust to let the hotplug script decide what to do. >If it wants to kill each unrunnable task with SIGPWR, it can. But if it >wants to let them live, it can. > I thought hotplug is allowed to fail? Thus you can have a hung system. Or what if the hotplug script itself becomes TASK_UNRUNNABLE? What if the process needs a guaranteed scheduling latency? (I dropped lhcs-devel@lists.sourceforge.net because its moderated) - 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/