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[23.128.96.18]) by mx.google.com with ESMTP id gv25si11551229ejc.161.2021.06.21.12.54.15; Mon, 21 Jun 2021 12:54:37 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231705AbhFUTzY (ORCPT + 99 others); Mon, 21 Jun 2021 15:55:24 -0400 Received: from mga02.intel.com ([134.134.136.20]:18472 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231209AbhFUTzX (ORCPT ); Mon, 21 Jun 2021 15:55:23 -0400 IronPort-SDR: KzD2/OVWEJpIuHEN/SFVCQ0J9nXNP7J+sBsh/jGm3xqgcS7G1U4jXG0+o5+L3ED4jWsVlwsTNo cbg+DW9gNcLg== X-IronPort-AV: E=McAfee;i="6200,9189,10022"; a="194058834" X-IronPort-AV: E=Sophos;i="5.83,289,1616482800"; d="scan'208";a="194058834" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jun 2021 12:53:08 -0700 IronPort-SDR: BXeXHIt2opCjgdU+kc8Fux/WE/IGgceIx7NAK8FoU2jtWaK8uRrDz6TFmRMSiSrR/nRBWRHYeL +a89fkhyTkvQ== X-IronPort-AV: E=Sophos;i="5.83,289,1616482800"; d="scan'208";a="453997736" Received: from bhooglan-mobl1.amr.corp.intel.com (HELO [10.255.228.227]) ([10.255.228.227]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jun 2021 12:53:07 -0700 Subject: Re: [PATCH -V8 02/10] mm/numa: automatically generate node migration order To: "Huang, Ying" , Zi Yan , Dave Hansen Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yang Shi , Michal Hocko , Wei Xu , David Rientjes , Dan Williams , David Hildenbrand , osalvador References: <20210618061537.434999-1-ying.huang@intel.com> <20210618061537.434999-3-ying.huang@intel.com> <79397FE3-4B08-4DE5-8468-C5CAE36A3E39@nvidia.com> <87v96anu6o.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <87v96anu6o.fsf@yhuang6-desk2.ccr.corp.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/19/21 1:18 AM, Huang, Ying wrote: >>> int next_demotion_node(int node) >>> { >>> - return node_demotion[node]; >>> + /* >>> + * node_demotion[] is updated without excluding >>> + * this function from running. READ_ONCE() avoids >>> + * reading multiple, inconsistent 'node' values >>> + * during an update. >>> + */ >>> + return READ_ONCE(node_demotion[node]); >>> } >> Is it necessary to have two separate patches to add node_demotion and >> next_demotion_node() then modify it immediately? Maybe merge Patch 1 into 2? >> >> Hmm, I just checked Patch 3 and it changes node_demotion again and uses RCU. >> I guess it might be much simpler to just introduce node_demotion with RCU >> in this patch and Patch 3 only takes care of hotplug events. > Hi, Dave, > > What do you think about this? > Squashing them seems like a good idea to me.