From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) by kanga.kvack.org (Postfix) with ESMTP id BA1AE6B4C5D for ; Wed, 28 Nov 2018 05:03:12 -0500 (EST) Received: by mail-qt1-f198.google.com with SMTP id n39so22883298qtn.18 for ; Wed, 28 Nov 2018 02:03:12 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id 1si4707103qvo.44.2018.11.28.02.03.11 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 28 Nov 2018 02:03:11 -0800 (PST) Subject: Re: [PATCH v2 5/5] mm, memory_hotplug: Refactor shrink_zone/pgdat_span References: <20181127162005.15833-1-osalvador@suse.de> <20181127162005.15833-6-osalvador@suse.de> <20181128065018.GG6923@dhcp22.suse.cz> <1543388866.2920.5.camel@suse.de> From: David Hildenbrand Message-ID: Date: Wed, 28 Nov 2018 11:03:08 +0100 MIME-Version: 1.0 In-Reply-To: <1543388866.2920.5.camel@suse.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Oscar Salvador , 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, linux-mm@kvack.org On 28.11.18 08:07, Oscar Salvador wrote: > 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. > I am also not sure if that can be done. Anyhow, simplifying first and getting rid later is in my opinion also good enough. One step at a time :) > 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 > -- Thanks, David / dhildenb