From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752596AbcCAIbg (ORCPT ); Tue, 1 Mar 2016 03:31:36 -0500 Received: from mx2.suse.de ([195.135.220.15]:39770 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751209AbcCAIbf (ORCPT ); Tue, 1 Mar 2016 03:31:35 -0500 Subject: Re: [RFC PATCH] mm: CONFIG_NR_ZONES_EXTENDED To: Dan Williams References: <20160128061914.32541.97351.stgit@dwillia2-desk3.amr.corp.intel.com> <20160201214213.2bdf9b4e.akpm@linux-foundation.org> <56D43AAB.2010802@suse.cz> <56D4DCFE.9040806@suse.cz> Cc: Andrew Morton , Rik van Riel , Dave Hansen , "linux-kernel@vger.kernel.org" , Linux MM , Mel Gorman , Mark , Joonsoo Kim , Sudip Mukherjee From: Vlastimil Babka Message-ID: <56D55359.3080809@suse.cz> Date: Tue, 1 Mar 2016 09:31:21 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/01/2016 03:06 AM, Dan Williams wrote: > On Mon, Feb 29, 2016 at 4:06 PM, Vlastimil Babka wrote: >> On 29.2.2016 18:55, Dan Williams wrote: >>> On Mon, Feb 29, 2016 at 4:33 AM, Vlastimil Babka wrote: >>>> On 02/02/2016 06:42 AM, Andrew Morton wrote: >>> >>> In this case it's already part of the equation because: >>> >>> config ZONE_DEVICE >>> depends on MEMORY_HOTPLUG >>> depends on MEMORY_HOTREMOVE >>> >>> ...and those in turn depend on SPARSEMEM. >> >> Fine, but then SPARSEMEM_VMEMMAP should be still an available subvariant of >> SPARSEMEM with SECTION_WIDTH=0. > > It should be, but not for the ZONE_DEVICE case. ZONE_DEVICE depends > on x86_64 which means ZONE_DEVICE also implies SPARSEMEM_VMEMMAP > since: > > config ARCH_SPARSEMEM_ENABLE > def_bool y > depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD > select SPARSEMEM_STATIC if X86_32 > select SPARSEMEM_VMEMMAP_ENABLE if X86_64 > > Now, if a future patch wants to reclaim page flags space for other > usages outside of ZONE_DEVICE it can do the work to handle the > SPARSEMEM_VMEMMAP=n case. I don't see a reason to fold that > distinction into the current patch given the current constraints. OK so that IUUC shows that x86_64 should be always fine without decreasing the range for NODES_SHIFT? That's basically my point - since there's a configuration where things don't fit (32bit?), the patch broadly decreases range for NODES_SHIFT for everyone, right? > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org >