From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx147.postini.com [74.125.245.147]) by kanga.kvack.org (Postfix) with SMTP id 030F86B0068 for ; Wed, 24 Oct 2012 21:18:04 -0400 (EDT) Date: Wed, 24 Oct 2012 18:17:52 -0700 From: Andrew Morton Subject: Re: [PATCH] add some drop_caches documentation and info messsge Message-Id: <20121024181752.de011615.akpm@linux-foundation.org> In-Reply-To: <1787395.7AzIesGUbB@vostro.rjw.lan> References: <20121012125708.GJ10110@dhcp22.suse.cz> <20121024210600.GA17037@liondog.tnic> <20121024141303.0797d6a1.akpm@linux-foundation.org> <1787395.7AzIesGUbB@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: "Rafael J. Wysocki" Cc: Borislav Petkov , Dave Hansen , Michal Hocko , linux-mm@kvack.org, KAMEZAWA Hiroyuki , KOSAKI Motohiro , LKML 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? Given that it's so easy to do from the hibernation script, I guess there's not much point... -- 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