From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id 6F9156B000E for ; Thu, 5 Apr 2018 04:27:12 -0400 (EDT) Received: by mail-wr0-f198.google.com with SMTP id z15so12970266wrh.10 for ; Thu, 05 Apr 2018 01:27:12 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 125si3547130wmr.31.2018.04.05.01.27.10 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 05 Apr 2018 01:27:11 -0700 (PDT) Date: Thu, 5 Apr 2018 10:27:08 +0200 From: Michal Hocko Subject: Re: [PATCH] mm/thp: don't count ZONE_MOVABLE as the target for freepage reserving Message-ID: <20180405082708.GA6312@dhcp22.suse.cz> References: <1522913236-15776-1-git-send-email-iamjoonsoo.kim@lge.com> <20180405075753.GZ6312@dhcp22.suse.cz> <20180405080539.GA631@js1304-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180405080539.GA631@js1304-desktop> Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Andrew Morton , "Kirill A . Shutemov" , Mel Gorman , Vlastimil Babka , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu 05-04-18 17:05:39, Joonsoo Kim wrote: > On Thu, Apr 05, 2018 at 09:57:53AM +0200, Michal Hocko wrote: > > On Thu 05-04-18 16:27:16, Joonsoo Kim wrote: > > > From: Joonsoo Kim > > > > > > ZONE_MOVABLE only has movable pages so we don't need to keep enough > > > freepages to avoid or deal with fragmentation. So, don't count it. > > > > > > This changes min_free_kbytes and thus min_watermark greatly > > > if ZONE_MOVABLE is used. It will make the user uses more memory. > > > > OK, but why does it matter. Has anybody seen this as an issue? > > There was a regression report for CMA patchset and I think that it is > related to this problem. CMA patchset makes the system uses one more > zone (ZONE_MOVABLE) and then increase min_free_kbytes. It reduces > usable memory and it could cause regression. > > http://lkml.kernel.org/r/20180102063528.GG30397@yexl-desktop Then this should be a part of the changelog along with some reproducible results, please. -- Michal Hocko SUSE Labs