From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 29 Dec 2002 21:45:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 29 Dec 2002 21:45:16 -0500 Received: from mnh-1-01.mv.com ([207.22.10.33]:6149 "EHLO ccure.karaya.com") by vger.kernel.org with ESMTP id ; Sun, 29 Dec 2002 21:45:15 -0500 Message-Id: <200212300245.VAA04199@ccure.karaya.com> X-Mailer: exmh version 2.0.2 To: Werner Almesberger cc: Alan Cox Cc: Rik van Riel , Anomalous Force , ebiederm@xmission.com, Linux Kernel Mailing List Subject: Re: holy grail In-Reply-To: Your message of "Sun, 29 Dec 2002 22:32:47 -0300." <20021229223247.C1363@almesberger.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sun, 29 Dec 2002 21:45:52 -0500 From: Jeff Dike Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org wa@almesberger.net said: > I see a certain trend towards mechanisms that can be useful for > process migration. E.g. the address space manipulations discussed for > UML seem to allow almost perfect reconstruction of processes. PIDs, > signals, anything with externally visible changes in kernel state With a UML running in skas mode, the process address space is identical to what it would be on the host. Migrating one to the host would be a matter of Sticking a process in it Releasing that process from ptrace Recreating the required kernel state in the host kernel Kicking the process out of the UML kernel and into userspace somehow Letting it run Step 3 is obviously where the meat of the problem is. The process needs to have available on it all the resources it had in UML - the same files network connections (puntable on a first pass) process relationships (I have no idea what to do about a parent process on the host, nor what to do with children whose parent has been migrated, or ipc mechanisms, except to do the Mosix thing and have little proxies sitting around passing information between UML and the host). And since I've brought up Mosix, as did Werner, the fastest way to get this working is probably to finish off the OpenMosix/UML port (which was close from what I heard), and cluster a UML and its host. You should get process migration for free. Just remember to prevent the host from trying to migrate a UML to itself. That would be very bad. Jeff