From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753555AbcEDTlu (ORCPT ); Wed, 4 May 2016 15:41:50 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:36568 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751423AbcEDTls (ORCPT ); Wed, 4 May 2016 15:41:48 -0400 Date: Wed, 4 May 2016 21:41:46 +0200 From: Michal Hocko To: Joonsoo Kim Cc: Joonsoo Kim , Andrew Morton , Vlastimil Babka , Mel Gorman , Minchan Kim , Alexander Potapenko , Linux Memory Management List , LKML Subject: Re: [PATCH 6/6] mm/page_owner: use stackdepot to store stacktrace Message-ID: <20160504194146.GF21490@dhcp22.suse.cz> References: <1462252984-8524-1-git-send-email-iamjoonsoo.kim@lge.com> <1462252984-8524-7-git-send-email-iamjoonsoo.kim@lge.com> <20160503085356.GD28039@dhcp22.suse.cz> <20160504021449.GA10256@js1304-P5Q-DELUXE> <20160504092133.GG29978@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 05-05-16 00:45:45, Joonsoo Kim wrote: > 2016-05-05 0:30 GMT+09:00 Joonsoo Kim : > > 2016-05-04 18:21 GMT+09:00 Michal Hocko : > >> On Wed 04-05-16 11:14:50, Joonsoo Kim wrote: > >>> On Tue, May 03, 2016 at 10:53:56AM +0200, Michal Hocko wrote: > >>> > On Tue 03-05-16 14:23:04, Joonsoo Kim wrote: > >> [...] > >>> > > Memory saving looks as following. (Boot 4GB memory system with page_owner) > >>> > > > >>> > > 92274688 bytes -> 25165824 bytes > >>> > > >>> > It is not clear to me whether this is after a fresh boot or some workload > >>> > which would grow the stack depot as well. What is a usual cap for the > >>> > memory consumption. > >>> > >>> It is static allocation size after a fresh boot. I didn't add size of > >>> dynamic allocation memory so it could be larger a little. See below line. > >>> > > >>> > > 72% reduction in static allocation size. Even if we should add up size of > >>> > > dynamic allocation memory, it would not that big because stacktrace is > >>> > > mostly duplicated. > >> > >> This would be true only if most of the allocation stacks are basically > >> same after the boot which I am not really convinced is true. But you are > >> right that the number of sublicates will grow only a little. I was > >> interested about how much is that little ;) > > > > After a fresh boot, it just uses 14 order-2 pages. > > I missed to add other information. Even after building the kernel, > it takes 20 order-2 pages. 20 * 4 * 4KB = 320 KB. Something like that would be useful to mention in the changelog because measuring right after the fresh boot without any reasonable workload sounds suspicious. -- Michal Hocko SUSE Labs