From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932445AbXGKMMK (ORCPT ); Wed, 11 Jul 2007 08:12:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761839AbXGKMLw (ORCPT ); Wed, 11 Jul 2007 08:11:52 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:49787 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756698AbXGKMLv (ORCPT ); Wed, 11 Jul 2007 08:11:51 -0400 From: "Rafael J. Wysocki" To: Miklos Szeredi Subject: Re: Hibernation Redesign Date: Wed, 11 Jul 2007 14:19:10 +0200 User-Agent: KMail/1.9.5 Cc: a1426z@gawab.com, jeremy@goop.org, jbms@cmu.edu, pavel@ucw.cz, nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org, akpm@linux-foundation.org References: <200707081737.21932.a1426z@gawab.com> <200707111350.41806.rjw@sisk.pl> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200707111419.11418.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday, 11 July 2007 13:54, Miklos Szeredi wrote: > > > > regarding the freezer, how it is bad and how we should drop it, > > > > because it breaks things (which NB is not true, because it doesn't). > > > > > > This thread started out from a bug, that seemed to be caused by the > > > freezer (we still don't exactly know what it was caused by), and the > > > discussion uncovered various problems _with_ the freezer, that up to > > > now no other _proper_ solutions have been propsed than to remove the > > > freezer. > > > > First, please list those problems for completness. Moreover, I think they > > should be documented if they haven't been yet. > > Suspend failing due to ordering requirements from fuse, I think you > documented this one. > > Suspend failing due to malicious/buggy fuse filesystem. > > Suspend failing if network filesystem is mounted, and network or > server is down. This is one of those "we can live with it" things > that only happen rarely, and it's annoying then, but soon forgotten. All of the above boil down to the freezer limitation regarding uninterruptible tasks. And yes, I think it should be explicitly documented. > Freezing of tasks is slowing down suspend. Don't know how serious > this is, suspend is pretty fast, but could possibly be even faster. Hmm, I don't know either. I'm not seeing this in my tests, but well, more data will be appreciated. The sync probably slows down more than the freezing itself ... > Don't know what the OLPC guys do to make suspending extremely quick, > are they freezing any tasks? They used to, but I'm not sure if they do. > > Second, there were many more problems with the freezer in the past and we > > were able to eliminate them over time. It sometimes is difficult to invent a > > viable solution on demand ... > > OK, if you elimitate all of the above problems with the freezer, I'll > say no more against it. I think the ordering issue may be eliminated, to some extent. I have a patch for that, but you were CCed on that patch series, so you should know. ;-) The other ones are more difficult, so time will tell. Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth