From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751016AbWFQItH (ORCPT ); Sat, 17 Jun 2006 04:49:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751086AbWFQItG (ORCPT ); Sat, 17 Jun 2006 04:49:06 -0400 Received: from smtp108.mail.mud.yahoo.com ([209.191.85.218]:16059 "HELO smtp108.mail.mud.yahoo.com") by vger.kernel.org with SMTP id S1751048AbWFQItF (ORCPT ); Sat, 17 Jun 2006 04:49:05 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=kClAna2bHFl34402tMVUnByFbIYF7ttQp7K73AGGX+kecIha6sC42N32EtiCI5P3Y5Xw5UB8R+Sz7d1YUGD5x97g1RMZGYJWdq3g9fUXlJDfbn9XGf+YG9UYiC3u0NninhSUYUALXUzV5MrVw8aJbezxKAsB7mDsbp74eaJLFdg= ; Message-ID: <4493C1FB.802@yahoo.com.au> Date: Sat, 17 Jun 2006 18:48:59 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: KAMEZAWA Hiroyuki CC: ak@suse.de, ashok.raj@intel.com, linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH] avoid cpu hot remove of cpus which have special RT tasks. References: <20060616162343.02c3ce62.kamezawa.hiroyu@jp.fujitsu.com> <20060616192654.50f4f6b7.kamezawa.hiroyu@jp.fujitsu.com> <200606161236.50302.ak@suse.de> <44937B16.3050204@yahoo.com.au> <20060617141216.dba310af.kamezawa.hiroyu@jp.fujitsu.com> <4493AF5C.4080600@yahoo.com.au> <20060617165319.458d913a.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20060617165319.458d913a.kamezawa.hiroyu@jp.fujitsu.com> 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 KAMEZAWA Hiroyuki wrote: > On Sat, 17 Jun 2006 17:29:32 +1000 > Nick Piggin wrote: > > >>>As SIGSTOP/KILL patch I posted, the apps shouldn't do unexpected >>>work, I think. >> >>I don't quite understand you here... the kernel doesn't need to enforce >>anything but a dumb fallback policy where userspace is otherwise capable >>of handling it themselves. > > > If all things about apps are properly maintained/managed, it is reconfigured > by the user/system admin *before* cpu hotremove. > > The case "the kernel have to move the task to other cpu which user doesn't want" > means the application is already broken. > > So, I think "stop mis-configurated process" can be one way for handling such apps. > > For example) > After exchanging broken cpu, the application can continue its work with the > same # of cpus. OK I can see what you're trying to achieve, but I don't know that it is worthwhile. Userspace is doing something wrong, and it isn't normally the kernel's job to detect that. When something like this comes up, sticking to the simplest semantics is often best. That said, it isn't a great deal of code to maintain, and not "incorrect" as such. So if you convince Ingo to pick it up, I wouldn't complain. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com