From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761614AbXGORlu (ORCPT ); Sun, 15 Jul 2007 13:41:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761483AbXGORla (ORCPT ); Sun, 15 Jul 2007 13:41:30 -0400 Received: from [212.12.190.206] ([212.12.190.206]:32865 "EHLO raad.intranet" rhost-flags-FAIL-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1759495AbXGORl3 (ORCPT ); Sun, 15 Jul 2007 13:41:29 -0400 From: Al Boldi To: jimmy bahuleyan Subject: Re: Hibernation considerations Date: Sun, 15 Jul 2007 20:40:28 +0300 User-Agent: KMail/1.5 Cc: "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, Alan Stern , Andrew Morton , "Eric W. Biederman" , "Huang, Ying" , Jeremy Maitin-Shepard , Kyle Moffett , Nigel Cunningham , Pavel Machek , pm list , david@lang.hm References: <200707151433.34625.rjw@sisk.pl> <200707151810.33554.a1426z@gawab.com> <469A3EB9.8000304@gmail.com> In-Reply-To: <469A3EB9.8000304@gmail.com> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <200707152040.28744.a1426z@gawab.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org jimmy bahuleyan wrote: > Al Boldi wrote: > > This should be the responsibility of the kexec'd hibernating kernel. > > Note though in (6), the normal kernel takes care of preparing devices, > > then the hibernating kernel dumps the image and either calls S4 or S3. > > On resume from S3 it can immediately switch over to the normal kernel, > > and from S4 the known bootup would occur. > > > >> (8) Hibernation and restore should not be too slow > >> > >> In my opinion, if more than one minute is needed to hibernate the > >> system with the help of certain hibernation framework, then this > >> framework is not very useful in practice. It might be useful to > >> perform some special tasks (eg. moving a server to another place > >> without taking it down), but it is not very useful, for example, to > >> notebook users. > > > > The latest hibernating kexec patches boot a kexec'd modular kernel with > > initramfs into crashkernel=16M@16M in less than one second. Switch-back > > is almost instant. Add to this the time required to either store or > > restore the image, and it may be obvious that this approach isn't > > slower, but maybe even faster than the current swsusp. > > What about (9)? Would it be that a user choosing to build a kernel with > hibernate support gets a additional modular kernel built (which he > should then use for resumption) or he should configure & build the > modular kernel independent of main kernel? > > Or will the Linux boot procedure change so that it always goes thru a > modular part followed by kexec (just to be uniform)? > > Although the kexec approach seems interesting, the final user-scenario > seems a bit complex (or confusing). Well, it may sound confusing because it is so unexpectedly simple. I didn't answer to (9) because from a user pov nothing should change, and everything should be scriptable such that the user wouldn't even notice the kernel using a new hibernation approach. Thanks! -- Al