From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933243Ab2JaRb6 (ORCPT ); Wed, 31 Oct 2012 13:31:58 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:50427 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932555Ab2JaRbz (ORCPT ); Wed, 31 Oct 2012 13:31:55 -0400 Date: Wed, 31 Oct 2012 18:31:54 +0100 From: Pavel Machek To: Borislav Petkov , Jiri Kosina , Andrew Morton , "Rafael J. Wysocki" , 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: <20121031173154.GA20660@elf.ucw.cz> References: <20121012125708.GJ10110@dhcp22.suse.cz> <20121024210600.GA17037@liondog.tnic> <20121024141303.0797d6a1.akpm@linux-foundation.org> <1787395.7AzIesGUbB@vostro.rjw.lan> <20121024181752.de011615.akpm@linux-foundation.org> <20121029095819.GA4326@liondog.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121029095819.GA4326@liondog.tnic> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 2012-10-29 10:58:19, Borislav Petkov wrote: > On Mon, Oct 29, 2012 at 09:59:59AM +0100, Jiri Kosina wrote: > > You might or might not want to do that. Dropping caches around suspend > > makes the hibernation process itself faster, but the realtime response > > of the applications afterwards is worse, as everything touched by user > > has to be paged in again. Also note that page-in is slower than reading hibernation image, because it is not compressed, and involves seeking. > Right, do you know of a real use-case where people hibernate, then > resume and still care about applications response time right afterwards? Hmm? When I resume from hibernate, I want to use my machine. *Everyone* cares about resume time afterwards. You move your mouse, and you don't want to wait for X to be paged-in. > Besides, once everything is swapped back in, perf. is back to normal, > i.e. like before suspending. Kernel will not normally swap anything in automatically. Some people do swapoff -a; swapon -a to work around that. (And yes, maybe some automatic-swap-in-when-there's-plenty-of-RAM would be useful.). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html