From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757332AbXD0V0W (ORCPT ); Fri, 27 Apr 2007 17:26:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757335AbXD0VZz (ORCPT ); Fri, 27 Apr 2007 17:25:55 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:58672 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757334AbXD0VZh (ORCPT ); Fri, 27 Apr 2007 17:25:37 -0400 From: "Rafael J. Wysocki" To: Pekka J Enberg Subject: Re: Back to the future. Date: Fri, 27 Apr 2007 23:24:42 +0200 User-Agent: KMail/1.9.5 Cc: Nigel Cunningham , Linus Torvalds , LKML References: <1177567481.5025.211.camel@nigel.suspend2.net> <1177654110.4737.91.camel@nigel.suspend2.net> In-Reply-To: MIME-Version: 1.0 Content-Disposition: inline Message-Id: <200704272324.43359.rjw@sisk.pl> Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Friday, 27 April 2007 08:18, Pekka J Enberg wrote: > On Fri, 27 Apr 2007, Nigel Cunningham wrote: > > COW is a possibility, but I understood (perhaps wrongly) that Linus was > > thinking of a single syscall or such like to prepare the snapshot. If > > you're going to start doing things like this, won't that mean you'd then > > have to update/redo the snapshot or somehow nullify the effect of > > anything the programs does so that doing it again after the snapshot is > > restored doesn't cause problems? > > No. The snapshot is just that. A snapshot in time. From kernel point of > view, it doesn't matter one bit what when you did it or if the state has > changed before you resume. It's up to userspace to make sure the user > doesn't do real work while the snapshot is being written to disk and > machine is shut down. Why do you think that keeping the user space frozen after 'snapshot' is a bad idea? I think that solves many of the problems you're discussing. Greetings, Rafael