From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 20 Dec 2017 13:16:49 -0800 From: Matthew Wilcox Subject: Re: [PATCH v3 0/3] create sysfs representation of ACPI HMAT Message-ID: <20171220211649.GA32200@bombadil.infradead.org> References: <20171214021019.13579-1-ross.zwisler@linux.intel.com> <20171214130032.GK16951@dhcp22.suse.cz> <20171218203547.GA2366@linux.intel.com> <20171220181937.GB12236@bombadil.infradead.org> <2da89d31-27a3-34ab-2dbb-92403c8215ec@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <2da89d31-27a3-34ab-2dbb-92403c8215ec@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Dave Hansen Cc: Michal Hocko , "Box, David E" , linux-mm@kvack.org, "Zheng, Lv" , linux-nvdimm@lists.01.org, "Rafael J. Wysocki" , "Anaczkowski, Lukasz" , Moore,Lukasz, "Erik , Len Brown" , John Hubbard , linuxppc-dev@lists.ozlabs.org, Jerome Glisse , devel@acpica.org, "Kogut, Jaroslaw" , "Koss, Marcin , linux-api@vger.kernel.org, Brice Goglin" , "Nachimuthu, Murugasamy , Rafael J. Wysocki" , linux-kernel@vger.kernel.org, Koziej,, "Joonas , Andrew Morton , Tim Chen" List-ID: On Wed, Dec 20, 2017 at 12:22:21PM -0800, Dave Hansen wrote: > 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. I think you're missing my larger point which is that I don't think this should be exposed to userspace as an ACPI feature. Because if you do, then it'll also be exposed to userspace as an openfirmware feature. And sooner or later a devicetree feature. And then writing a portable program becomes an exercise in suffering. So, what's the right place in sysfs that isn't tied to ACPI? A new directory or set of directories under /sys/devices/system/memory/ ? _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH v3 0/3] create sysfs representation of ACPI HMAT Date: Wed, 20 Dec 2017 13:16:49 -0800 Message-ID: <20171220211649.GA32200@bombadil.infradead.org> References: <20171214021019.13579-1-ross.zwisler@linux.intel.com> <20171214130032.GK16951@dhcp22.suse.cz> <20171218203547.GA2366@linux.intel.com> <20171220181937.GB12236@bombadil.infradead.org> <2da89d31-27a3-34ab-2dbb-92403c8215ec@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from bombadil.infradead.org ([65.50.211.133]:46187 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755637AbdLTVQw (ORCPT ); Wed, 20 Dec 2017 16:16:52 -0500 Content-Disposition: inline In-Reply-To: <2da89d31-27a3-34ab-2dbb-92403c8215ec@intel.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Dave Hansen Cc: Ross Zwisler , 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 On Wed, Dec 20, 2017 at 12:22:21PM -0800, Dave Hansen wrote: > 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. I think you're missing my larger point which is that I don't think this should be exposed to userspace as an ACPI feature. Because if you do, then it'll also be exposed to userspace as an openfirmware feature. And sooner or later a devicetree feature. And then writing a portable program becomes an exercise in suffering. So, what's the right place in sysfs that isn't tied to ACPI? A new directory or set of directories under /sys/devices/system/memory/ ? From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756473AbdLTVQz (ORCPT ); Wed, 20 Dec 2017 16:16:55 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:46187 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755637AbdLTVQw (ORCPT ); Wed, 20 Dec 2017 16:16:52 -0500 Date: Wed, 20 Dec 2017 13:16:49 -0800 From: Matthew Wilcox To: Dave Hansen Cc: Ross Zwisler , 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 Subject: Re: [PATCH v3 0/3] create sysfs representation of ACPI HMAT Message-ID: <20171220211649.GA32200@bombadil.infradead.org> References: <20171214021019.13579-1-ross.zwisler@linux.intel.com> <20171214130032.GK16951@dhcp22.suse.cz> <20171218203547.GA2366@linux.intel.com> <20171220181937.GB12236@bombadil.infradead.org> <2da89d31-27a3-34ab-2dbb-92403c8215ec@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2da89d31-27a3-34ab-2dbb-92403c8215ec@intel.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 20, 2017 at 12:22:21PM -0800, Dave Hansen wrote: > 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. I think you're missing my larger point which is that I don't think this should be exposed to userspace as an ACPI feature. Because if you do, then it'll also be exposed to userspace as an openfirmware feature. And sooner or later a devicetree feature. And then writing a portable program becomes an exercise in suffering. So, what's the right place in sysfs that isn't tied to ACPI? A new directory or set of directories under /sys/devices/system/memory/ ? From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 0A6FC6B0069 for ; Wed, 20 Dec 2017 16:16:56 -0500 (EST) Received: by mail-pg0-f70.google.com with SMTP id z25so14771447pgu.18 for ; Wed, 20 Dec 2017 13:16:56 -0800 (PST) Received: from bombadil.infradead.org (bombadil.infradead.org. [65.50.211.133]) by mx.google.com with ESMTPS id b35si13069218plh.729.2017.12.20.13.16.54 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 20 Dec 2017 13:16:55 -0800 (PST) Date: Wed, 20 Dec 2017 13:16:49 -0800 From: Matthew Wilcox Subject: Re: [PATCH v3 0/3] create sysfs representation of ACPI HMAT Message-ID: <20171220211649.GA32200@bombadil.infradead.org> References: <20171214021019.13579-1-ross.zwisler@linux.intel.com> <20171214130032.GK16951@dhcp22.suse.cz> <20171218203547.GA2366@linux.intel.com> <20171220181937.GB12236@bombadil.infradead.org> <2da89d31-27a3-34ab-2dbb-92403c8215ec@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2da89d31-27a3-34ab-2dbb-92403c8215ec@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Ross Zwisler , 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 On Wed, Dec 20, 2017 at 12:22:21PM -0800, Dave Hansen wrote: > 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. I think you're missing my larger point which is that I don't think this should be exposed to userspace as an ACPI feature. Because if you do, then it'll also be exposed to userspace as an openfirmware feature. And sooner or later a devicetree feature. And then writing a portable program becomes an exercise in suffering. So, what's the right place in sysfs that isn't tied to ACPI? A new directory or set of directories under /sys/devices/system/memory/ ? -- 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