Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936050Ab2JYUNE (ORCPT ); Thu, 25 Oct 2012 16:13:04 -0400 Received: from ogre.sisk.pl ([193.178.161.156]:37704 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934218Ab2JYUNC (ORCPT ); Thu, 25 Oct 2012 16:13:02 -0400 From: "Rafael J. Wysocki" To: Andrew Morton Cc: Borislav Petkov , Dave Hansen , Michal Hocko , linux-mm@kvack.org, KAMEZAWA Hiroyuki , KOSAKI Motohiro , LKML Subject: Re: [PATCH] add some drop_caches documentation and info messsge Date: Thu, 25 Oct 2012 22:16:58 +0200 Message-ID: <1484035.7aMAWXqOf7@vostro.rjw.lan> User-Agent: KMail/4.8.5 (Linux/3.6.3-8-desktop; KDE/4.8.5; x86_64; ; ) In-Reply-To: <20121024181752.de011615.akpm@linux-foundation.org> References: <20121012125708.GJ10110@dhcp22.suse.cz> <1787395.7AzIesGUbB@vostro.rjw.lan> <20121024181752.de011615.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2021 Lines: 50 On Wednesday, October 24, 2012 06:17:52 PM Andrew Morton wrote: > On Thu, 25 Oct 2012 00:04:46 +0200 "Rafael J. Wysocki" wrote: > > > On Wednesday 24 of October 2012 14:13:03 Andrew Morton wrote: > > > On Wed, 24 Oct 2012 23:06:00 +0200 > > > Borislav Petkov wrote: > > > > > > > On Wed, Oct 24, 2012 at 01:48:36PM -0700, Andrew Morton wrote: > > > > > Well who knows. Could be that people's vm *does* suck. Or they have > > > > > some particularly peculiar worklosd or requirement[*]. Or their VM > > > > > *used* to suck, and the drop_caches is not really needed any more but > > > > > it's there in vendor-provided code and they can't practically prevent > > > > > it. > > > > > > > > I have drop_caches in my suspend-to-disk script so that the hibernation > > > > image is kept at minimum and suspend times are as small as possible. > > > > > > hm, that sounds smart. > > > > > > > Would that be a valid use-case? > > > > > > I'd say so, unless we change the kernel to do that internally. We do > > > have the hibernation-specific shrink_all_memory() in the vmscan code. > > > We didn't see fit to document _why_ that exists, but IIRC it's there to > > > create enough free memory for hibernation to be able to successfully > > > complete, but no more. > > > > That's correct. > > Well, my point was: how about the idea of reclaiming clean pagecache > (and inodes, dentries, etc) before hibernation so we read/write less > disk data? We may actually want to write more into the image to improve post-resume responsiveness. > Given that it's so easy to do from the hibernation script, I guess > there's not much point... Well, I'd say so. :-) -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/