From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932686AbWBULka (ORCPT ); Tue, 21 Feb 2006 06:40:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932702AbWBULka (ORCPT ); Tue, 21 Feb 2006 06:40:30 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:1705 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S932686AbWBULk3 (ORCPT ); Tue, 21 Feb 2006 06:40:29 -0500 Date: Tue, 21 Feb 2006 12:39:52 +0100 From: Pavel Machek To: Nigel Cunningham Cc: Andy Lutomirski , Matthias Hensler , kernel list , Sebastian Kgler , rjw@sisk.pl Subject: Re: Which is simpler? (Was Re: [Suspend2-devel] Re: [ 00/10] [Suspend2] Modules support.) Message-ID: <20060221113952.GR21557@elf.ucw.cz> References: <20060201113710.6320.68289.stgit@localhost.localdomain> <20060220094728.GD19293@kobayashi-maru.wspse.de> <43FA97D9.4070902@myrealbox.com> <200602211446.04123.nigel@suspend2.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200602211446.04123.nigel@suspend2.net> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > > I can only speak for myself, but I want to work with my system from the > > > moment my desktop is back. > > > > I Am Not A VM Hacker, but: > > > > What's the point of saving pagecache during suspend? This seems like a > > total waste. Why don't we save a list of pages in pagecache to disk, > > then, after resume, prefetch them all back in. This will slow down > > resume (extra seeks, minimized if we sort the list, and inability > > to compress these pages), but it will speed up suspend, and it sounds > > a lot simpler. There's already a patch to add swap prefetching, and > > this can't be much more complicated. > > The page cache contains the process pages, among other things, so it can't all > be discarded with impunity. You're right in suggesting that > discarding them Well, we already have perfectly good code to free pagecache. > and then prefetching them would be a potential alternative, but it would > actually be more complicated: you'd still have to remember which pages you > wanted to fault back in, and some how store that info in the > image. You'd That's okay. Imagine "cat /proc/vm/pagecache-contents > /tmp/delme" just before suspend and "cat /tmp/delme | prefetcher" just after it. Prefetcher is actually simple app that reads specified pages, then discards them. It can actually be done in userspace around regular swsusp/uswsusp/suspend2 with no impact on it. Pavel -- Web maintainer for suspend.sf.net (www.sf.net/projects/suspend) wanted...