From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi1-f200.google.com (mail-oi1-f200.google.com [209.85.167.200]) by kanga.kvack.org (Postfix) with ESMTP id EC7A66B427C for ; Mon, 26 Nov 2018 10:52:14 -0500 (EST) Received: by mail-oi1-f200.google.com with SMTP id r131so5640466oia.7 for ; Mon, 26 Nov 2018 07:52:14 -0800 (PST) Received: from foss.arm.com (foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id k11si292798otk.44.2018.11.26.07.52.13 for ; Mon, 26 Nov 2018 07:52:13 -0800 (PST) Subject: Re: [PATCH 0/7] ACPI HMAT memory sysfs representation References: <20181114224902.12082-1-keith.busch@intel.com> <1ed406b2-b85f-8e02-1df0-7c39aa21eca9@arm.com> <4ea6e80f-80ba-6992-8aa0-5c2d88996af7@intel.com> <9015e51a-3584-7bb2-cc5e-25b0ec8e5494@intel.com> From: Anshuman Khandual Message-ID: <4b9e30ea-aa8e-cfd7-230b-1d5b0a8837f4@arm.com> Date: Mon, 26 Nov 2018 21:22:13 +0530 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams , Dave Hansen Cc: Keith Busch , Linux Kernel Mailing List , Linux ACPI , Linux MM , Greg KH , "Rafael J. Wysocki" On 11/24/2018 02:43 AM, Dan Williams wrote: > On Fri, Nov 23, 2018 at 11:21 AM Dave Hansen wrote: >> >> On 11/22/18 10:42 PM, Anshuman Khandual wrote: >>> Are we willing to go in the direction for inclusion of a new system >>> call, subset of it appears on sysfs etc ? My primary concern is not >>> how the attribute information appears on the sysfs but lack of it's >>> completeness. >> >> A new system call makes total sense to me. I have the same concern >> about the completeness of what's exposed in sysfs, I just don't see a >> _route_ to completeness with sysfs itself. Thus, the minimalist >> approach as a first step. > > Outside of platform-firmware-id to Linux-numa-node-id what other > userspace API infrastructure does the kernel need to provide? It seems > userspace enumeration of memory attributes is fully enabled once the > firmware-to-Linux identification is established. Which is true if the user space is required to probe the memory attribute values for the platform-firmware-id from the platform and then request required memory from corresponding Linux-numa-node-id via standard mm interfaces like mbind(). But in this patch series we are not mapping platform-firmware-id to Linux-numa-node-id. We are exporting properties applicable to Linux nodes (Linux-numa-node-id). Even if platform-firmware-id to Linux-numa-node-id is required it can be done through a new file like the following. Applications can just take the platform_id node and query platform about it's properties. /sys/devices/system/node/nodeX/platform_id This above interface would have been okay as its just an extension of the existing node information on sysfs. But thats not the case with this proposal.