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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D0E6C7EE23 for ; Fri, 12 May 2023 16:47:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231464AbjELQrX (ORCPT ); Fri, 12 May 2023 12:47:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40688 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230102AbjELQrW (ORCPT ); Fri, 12 May 2023 12:47:22 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1B7E635B8; Fri, 12 May 2023 09:47:21 -0700 (PDT) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.206]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4QHvhl6Mpjz6J6xk; Sat, 13 May 2023 00:43:19 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Fri, 12 May 2023 17:47:18 +0100 Date: Fri, 12 May 2023 17:47:17 +0100 From: Jonathan Cameron To: Dan Williams CC: Dave Jiang , , , , , Subject: Re: [PATCH] base/node / acpi: Change 'node_hmem_attrs' to 'access_coordinates' Message-ID: <20230512174717.00006046@Huawei.com> In-Reply-To: <645e6215ee0de_1e6f2945e@dwillia2-xfh.jf.intel.com.notmuch> References: <168332248685.2190392.1983307884583782116.stgit@djiang5-mobl3> <20230510171445.00004cea@Huawei.com> <645e6215ee0de_1e6f2945e@dwillia2-xfh.jf.intel.com.notmuch> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml100004.china.huawei.com (7.191.162.219) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 12 May 2023 08:58:14 -0700 Dan Williams wrote: > Jonathan Cameron wrote: > > On Fri, 05 May 2023 14:34:46 -0700 > > Dave Jiang wrote: > > > > > Dan Williams suggested changing the struct 'node_hmem_attrs' to > > > 'access_coordinates' [1]. The struct is a container of r/w-latency and > > > r/w-bandwidth numbers. Moving forward, this container will also be used by > > > CXL to store the performance characteristics of each link hop in > > > the PCIE/CXL topology. So, where node_hmem_attrs is just the access > > > parameters of a memory-node, access_coordinates applies more broadly > > > to hardware topology characteristics. > > > > Not that it hugely matters, but why the term "coordinates"? > > Looks like Dan used that term, but I've not come across it being applied > > in this circumstances and it isn't a case of being immediately obvious > > to me what it means. > > > > If it is just another vague entry in kernel word soup then I don't really > > mind the term, but nice to give some reasoning in patch description. > > The inspiration here was past discussions that have been had about > potential API changes for userspace contending with multiple memory > types. The observation was that seemed like an exercise in having the > application identify "where" it falls on a spectrum of bandwidth and > latency needs. > > So it's a tuple of read/write-latency and read/write-bandwidth. > "Coordinates" is not a perfect fit. Sometimes it is just conveying > values in isolation not a "location" relative to other performance > points, but in the end this data is used to identify the performance > operation point of a given memory-node. Works for me. Can we add that to the patch description for the historians? Having read a load more of the code using it, it now feels natural to me. Thanks, Jonathan