From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753108AbZEDJ2d (ORCPT ); Mon, 4 May 2009 05:28:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751601AbZEDJ2Y (ORCPT ); Mon, 4 May 2009 05:28:24 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:43206 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750749AbZEDJ2X (ORCPT ); Mon, 4 May 2009 05:28:23 -0400 Date: Mon, 4 May 2009 11:31:21 +0200 From: Pavel Machek To: "Rafael J. Wysocki" Cc: Wu Fengguang , Andrew Morton , torvalds@linux-foundation.org, jens.axboe@oracle.com, alan-jenkins@tuffmail.co.uk, linux-kernel@vger.kernel.org, kernel-testers@vger.kernel.org, linux-pm@lists.linux-foundation.org Subject: Re: [PATCH 3/4] PM/Hibernate: Use memory allocations to free memory (rev. 2) Message-ID: <20090504093121.GB30306@elf.ucw.cz> References: <200905030224.21471.rjw@sisk.pl> <20090503115127.GA9661@localhost> <200905031822.55260.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200905031822.55260.rjw@sisk.pl> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun 2009-05-03 18:22:54, Rafael J. Wysocki wrote: > On Sunday 03 May 2009, Wu Fengguang wrote: > > On Sun, May 03, 2009 at 02:24:20AM +0200, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki > > > > > > Modify the hibernation memory shrinking code so that it will make > > > memory allocations to free memory instead of using an artificial > > > memory shrinking mechanism for that. Remove the shrinking of > > > memory from the suspend-to-RAM code, where it is not really > > > necessary. Finally, remove the no longer used memory shrinking > > > functions from mm/vmscan.c . > > > > > > [rev. 2: Use the existing memory bitmaps for marking preallocated > > > image pages and use swsusp_free() from releasing them, introduce > > > GFP_IMAGE, add comments describing the memory shrinking strategy.] > > > > > > Signed-off-by: Rafael J. Wysocki > > > --- > > > kernel/power/main.c | 20 ------ > > > kernel/power/snapshot.c | 132 +++++++++++++++++++++++++++++++++----------- > > > mm/vmscan.c | 142 ------------------------------------------------ > > > 3 files changed, 101 insertions(+), 193 deletions(-) > > > > > > Index: linux-2.6/kernel/power/snapshot.c > > > =================================================================== > > > --- linux-2.6.orig/kernel/power/snapshot.c > > > +++ linux-2.6/kernel/power/snapshot.c > > > @@ -1066,41 +1066,97 @@ void swsusp_free(void) > > > buffer = NULL; > > > } > > > > > > +/* Helper functions used for the shrinking of memory. */ > > > + > > > +#ifdef CONFIG_HIGHMEM > > > +#define GFP_IMAGE (GFP_KERNEL | __GFP_HIGHMEM | __GFP_NO_OOM_KILL) > > > +#else > > > +#define GFP_IMAGE (GFP_KERNEL | __GFP_NO_OOM_KILL) > > > +#endif > > > > The CONFIG_HIGHMEM test is not necessary: __GFP_HIGHMEM is always defined. > > > > > +#define SHRINK_BITE 10000 > > > > This is ~40MB. A full scan of (for example) 8G pages will be time > > consuming, not to mention we have to do it 2*(8G-500M)/40M = 384 times! > > > > Can we make it a LONG_MAX? > > No, I don't think so. The problem is the number of pages we'll need to copy > is generally shrinking as we allocate memory, so we can't do that in one shot. > > We can make it a greater number, but I don't really think it would be a good > idea to make it greater than 100 MB. Well, even 100MB is quite big: on 128MB machine, that will probably mean freeing all the memory (instead of "as much as needed"). And that memory needs to go to disk, so it will be slow. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html