Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756018AbdLTUW2 (ORCPT ); Wed, 20 Dec 2017 15:22:28 -0500 Received: from mga02.intel.com ([134.134.136.20]:52875 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755543AbdLTUW0 (ORCPT ); Wed, 20 Dec 2017 15:22:26 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.45,433,1508828400"; d="scan'208";a="4125627" Subject: Re: [PATCH v3 0/3] create sysfs representation of ACPI HMAT To: Matthew Wilcox , Ross Zwisler References: <20171214021019.13579-1-ross.zwisler@linux.intel.com> <20171214130032.GK16951@dhcp22.suse.cz> <20171218203547.GA2366@linux.intel.com> <20171220181937.GB12236@bombadil.infradead.org> Cc: Michal Hocko , linux-kernel@vger.kernel.org, "Anaczkowski, Lukasz" , "Box, David E" , "Kogut, Jaroslaw" , "Koss, Marcin" , "Koziej, Artur" , "Lahtinen, Joonas" , "Moore, Robert" , "Nachimuthu, Murugasamy" , "Odzioba, Lukasz" , "Rafael J. Wysocki" , "Rafael J. Wysocki" , "Schmauss, Erik" , "Verma, Vishal L" , "Zheng, Lv" , Andrew Morton , Balbir Singh , Brice Goglin , Dan Williams , Jerome Glisse , John Hubbard , Len Brown , Tim Chen , devel@acpica.org, linux-acpi@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@lists.01.org, linux-api@vger.kernel.org, linuxppc-dev@lists.ozlabs.org From: Dave Hansen Message-ID: <2da89d31-27a3-34ab-2dbb-92403c8215ec@intel.com> Date: Wed, 20 Dec 2017 12:22:21 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <20171220181937.GB12236@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 715 Lines: 13 On 12/20/2017 10:19 AM, Matthew Wilcox wrote: > I don't know what the right interface is, but my laptop has a set of > /sys/devices/system/memory/memoryN/ directories. Perhaps this is the > right place to expose write_bw (etc). Those directories are already too redundant and wasteful. I think we'd really rather not add to them. In addition, it's technically possible to have a memory section span NUMA nodes and have different performance properties, which make it impossible to represent there. In any case, ACPI PXM's (Proximity Domains) are guaranteed to have uniform performance properties in the HMAT, and we just so happen to always create one NUMA node per PXM. So, NUMA nodes really are a good fit.