Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933268Ab2JYBSG (ORCPT ); Wed, 24 Oct 2012 21:18:06 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:43325 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933171Ab2JYBSE (ORCPT ); Wed, 24 Oct 2012 21:18:04 -0400 Date: Wed, 24 Oct 2012 18:17:52 -0700 From: Andrew Morton To: "Rafael J. Wysocki" 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 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> X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.9; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1692 Lines: 41 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 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/