From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755083AbXGHXA5 (ORCPT ); Sun, 8 Jul 2007 19:00:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751897AbXGHXAs (ORCPT ); Sun, 8 Jul 2007 19:00:48 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:32946 "EHLO amd.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751835AbXGHXAr (ORCPT ); Sun, 8 Jul 2007 19:00:47 -0400 Date: Mon, 9 Jul 2007 01:00:42 +0200 From: Pavel Machek To: david@lang.hm Cc: Benjamin Herrenschmidt , "Rafael J. Wysocki" , Alan Stern , Kyle Moffett , Nigel Cunningham , Matthew Garrett , linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org Subject: Re: hibernation/snapshot design [was Re: [PATCH] Remove process freezer from suspend to RAM pathway] Message-ID: <20070708230042.GH5401@elf.ucw.cz> References: <200707082115.27363.rjw@sisk.pl> <1183928612.3388.289.camel@localhost.localdomain> <200707082345.27859.rjw@sisk.pl> <1183931688.3388.316.camel@localhost.localdomain> <20070708221315.GF5401@elf.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.11+cvs20060126 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > >>>Actaully, I'm perfectly fine with that, as long as each task blocked by > >>>the > >>>driver due to suspend has PF_FROZEN (or something similar) set. Then, at > >>>least theoretically, we'll be able to drop the freezer from the suspend > >>>code > >>>path and move it after device_suspend() (or the hibernation-specific > >>>equivalent) for hibernation (in that case there shouldn't be a problem > >>>with > >>>any task waiting on I/O while the freezer is running ;-)). > >> > >>I don't see the need for a freezer for snapshot but that's a different > >>issue. (stop_machine looks good enough to me). > > > >Freezer is not needed for snapshot -- it is needed so that we can > >write out the snapshot to disk without the need for special > >drivers/block/simple-ide-for-suspend.c. (We are doing snapshot, then > >write to disk from userland code in uswsusp). > > instead of trying to freeze most of the system, could you do something > like start a virtual machine sandbox to write the data out, and not let > any userspace other then the sandbox operate? > > you would need to throw away disk buffers so that you don't mix current > pending I/O with I/O from the sandbox, and this would be a visable change > for how suspend is setup, but wouldn't this work? It feels kind of expensive, but yes, we could use another kernel for doing the dump. Kdump people are using that. We could use hypervisor for doing the dump. Xen people are doing that. (But I do not think any of those solutions is suitable for "lets hibernate my notebook" case). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html