From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) by kanga.kvack.org (Postfix) with ESMTP id 974A06B4BAE for ; Wed, 28 Nov 2018 02:08:05 -0500 (EST) Received: by mail-ed1-f71.google.com with SMTP id w15so12062100edl.21 for ; Tue, 27 Nov 2018 23:08:05 -0800 (PST) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id v4si2267644ede.46.2018.11.27.23.08.04 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Nov 2018 23:08:04 -0800 (PST) Message-ID: <1543388866.2920.5.camel@suse.de> Subject: Re: [PATCH v2 5/5] mm, memory_hotplug: Refactor shrink_zone/pgdat_span From: Oscar Salvador Date: Wed, 28 Nov 2018 08:07:46 +0100 In-Reply-To: <20181128065018.GG6923@dhcp22.suse.cz> References: <20181127162005.15833-1-osalvador@suse.de> <20181127162005.15833-6-osalvador@suse.de> <20181128065018.GG6923@dhcp22.suse.cz> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: akpm@linux-foundation.org, dan.j.williams@intel.com, pavel.tatashin@microsoft.com, jglisse@redhat.com, Jonathan.Cameron@huawei.com, rafael@kernel.org, david@redhat.com, linux-mm@kvack.org On Wed, 2018-11-28 at 07:50 +0100, Michal Hocko wrote: > > I didn't get to read through this whole series but one thing that is > on > my todo list for a long time is to remove all this stuff. I do not > think > we really want to simplify it when there shouldn't be any real reason > to > have it around at all. Why do we need to shrink zone/node at all? > > Now that we can override and assign memory to both normal na movable > zones I think we should be good to remove shrinking. I feel like I am missing a piece of obvious information here. Right now, we shrink zone/node to decrease spanned pages. I thought this was done for consistency, and in case of the node, in try_offline_node we use the spanned pages to go through all sections to check whether the node can be removed or not. >>From your comment, I understand that we do not really care about spanned pages. Why? Could you please expand on that? And if we remove it, would not this give to a user "bad"/confusing information when looking at /proc/zoneinfo? Thanks -- Oscar Salvador SUSE L3