From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id AA8E26B004F for ; Fri, 15 May 2009 09:09:41 -0400 (EDT) Date: Fri, 15 May 2009 15:09:31 +0200 From: Pavel Machek Subject: Re: [PATCH 4/6] PM/Hibernate: Rework shrinking of memory Message-ID: <20090515130930.GB1976@elf.ucw.cz> References: <200905070040.08561.rjw@sisk.pl> <200905132356.39481.rjw@sisk.pl> <20090514094046.GF6417@elf.ucw.cz> <200905141949.53108.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200905141949.53108.rjw@sisk.pl> Sender: owner-linux-mm@kvack.org To: "Rafael J. Wysocki" Cc: Andrew Morton , linux-pm@lists.linux-foundation.org, fengguang.wu@intel.com, linux-kernel@vger.kernel.org, nigel@tuxonice.net, rientjes@google.com, linux-mm@kvack.org List-ID: On Thu 2009-05-14 19:49:52, Rafael J. Wysocki wrote: > On Thursday 14 May 2009, Pavel Machek wrote: > > > > > > > > The main point (I thought) was to remove shrink_all_memory(). Instead, > > > > > > we're retaining it and adding even more stuff? > > > > > > > > > > The idea is that afterwards we can drop shrink_all_memory() once the > > > > > performance problem has been resolved. Also, we now allocate memory for the > > > > > image using GFP_KERNEL instead of doing it with GFP_ATOMIC after freezing > > > > > devices. I'd think that's an improvement? > > > > > > > > Dunno. GFP_KERNEL might attempt to do writeback/swapout/etc, which > > > > could be embarrassing if the devices are frozen. > > > > > > They aren't, because the preallocation is done upfront, so once the OOM killer > > > has been taken care of, it's totally safe. :-) > > > > As is GFP_ATOMIC. Except that GFP_KERNEL will cause catastrophic > > consequences when accounting goes wrong. (New kernel's idea of what is > > on disk will differ from what is _really_ on disk.) > > > > If accounting is right, GFP_ATOMIC and GFP_KERNEL is equivalent. > > > > If accounting is wrong, GFP_ATOMIC will fail with NULL, while > > GFP_KERNEL will do something bad. > > > > I'd keep GFP_ATOMIC (or GFP_NOIO or similar). > > Repeating myself: with this and the next patch applied, we preallocate memory > for the image _before_ freezing devices and therefore it is safe to use > GFP_KERNEL, because the OOM killer has been taken care of by [3/6]. Aha, I misparsed the sentecnes above. Acked-by: Pavel Machek Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org