From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74D5BC10F29 for ; Tue, 17 Mar 2020 13:44:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 405722075E for ; Tue, 17 Mar 2020 13:44:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 405722075E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E0E116B0005; Tue, 17 Mar 2020 09:44:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DBE506B0006; Tue, 17 Mar 2020 09:44:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CFAEA6B0007; Tue, 17 Mar 2020 09:44:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0035.hostedemail.com [216.40.44.35]) by kanga.kvack.org (Postfix) with ESMTP id B8BBF6B0005 for ; Tue, 17 Mar 2020 09:44:49 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 8E079824556B for ; Tue, 17 Mar 2020 13:44:49 +0000 (UTC) X-FDA: 76604974698.22.sail05_644b8e06f0610 X-HE-Tag: sail05_644b8e06f0610 X-Filterd-Recvd-Size: 3225 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Tue, 17 Mar 2020 13:44:49 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 44F85AD1E; Tue, 17 Mar 2020 13:44:47 +0000 (UTC) Subject: Re: [PATCH 1/3] powerpc/numa: Set numa_node for all possible cpus To: Michal Hocko Cc: Srikar Dronamraju , Sachin Sant , Linus Torvalds , LKML , linux-mm@kvack.org, Mel Gorman , "Kirill A. Shutemov" , Andrew Morton , linuxppc-dev@lists.ozlabs.org, Christopher Lameter , Joonsoo Kim , Kirill Tkhai References: <20200311110237.5731-1-srikar@linux.vnet.ibm.com> <20200311110237.5731-2-srikar@linux.vnet.ibm.com> <20200311115735.GM23944@dhcp22.suse.cz> <20200312052707.GA3277@linux.vnet.ibm.com> <5e5c736a-a88c-7c76-fc3d-7bc765e8dcba@suse.cz> <20200312131438.GB3277@linux.vnet.ibm.com> <61437352-8b54-38fa-4471-044a65c9d05a@suse.cz> <20200312161310.GC3277@linux.vnet.ibm.com> <20200316090652.GC11482@dhcp22.suse.cz> From: Vlastimil Babka Message-ID: <65b99db6-3bdf-6caa-74e5-6d6b681f16b5@suse.cz> Date: Tue, 17 Mar 2020 14:44:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200316090652.GC11482@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 3/16/20 10:06 AM, Michal Hocko wrote: > On Thu 12-03-20 17:41:58, Vlastimil Babka wrote: > [...] >> with nid present in: >> N_POSSIBLE - pgdat might not exist, node_to_mem_node() must return some online > > I would rather have a dummy pgdat for those. Have a look at > $ git grep "NODE_DATA.*->" | wc -l > 63 > > Who knows how many else we have there. I haven't looked more closely. > Besides that what is a real reason to not have pgdat ther and force all > users of a $random node from those that the platform considers possible > for special casing? Is that a memory overhead? Is that really a thing? I guess we can ignore memory overhead. I guess there only might be some concern that for nodes that are initially offline, we will allocate the pgdat on a different node, and after they are online, it will stay on a different node with more access latency from local cpus. If we only allocate for online nodes, it can always be local? But I guess it doesn't matter that much. > Somebody has suggested to tweak some of the low level routines to do the > special casing but I really have to say I do not like that. We shouldn't > use the first online node or anything like that. We should simply always > follow the topology presented by FW and of that we need to have a pgdat. >