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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A610CC04EB8 for ; Tue, 4 Dec 2018 20:47:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 743202081C for ; Tue, 4 Dec 2018 20:47:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 743202081C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=deltatee.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726488AbeLDUrb (ORCPT ); Tue, 4 Dec 2018 15:47:31 -0500 Received: from ale.deltatee.com ([207.54.116.67]:54352 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725867AbeLDUra (ORCPT ); Tue, 4 Dec 2018 15:47:30 -0500 Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtp (Exim 4.89) (envelope-from ) id 1gUHbE-0000I1-08; Tue, 04 Dec 2018 13:47:20 -0700 To: Andi Kleen Cc: Jerome Glisse , Dan Williams , Linux MM , Andrew Morton , Linux Kernel Mailing List , "Rafael J. Wysocki" , Ross Zwisler , Dave Hansen , Haggai Eran , balbirs@au1.ibm.com, "Aneesh Kumar K.V" , Benjamin Herrenschmidt , "Kuehling, Felix" , Philip.Yang@amd.com, "Koenig, Christian" , "Blinzer, Paul" , John Hubbard , rcampbell@nvidia.com References: <20181203233509.20671-1-jglisse@redhat.com> <20181203233509.20671-3-jglisse@redhat.com> <875zw98bm4.fsf@linux.intel.com> <20181204182421.GC2937@redhat.com> <20181204185725.GE2937@redhat.com> <20181204201432.GH18167@tassilo.jf.intel.com> From: Logan Gunthorpe Message-ID: <8ed92aba-a129-144f-34ab-f77102d54cfc@deltatee.com> Date: Tue, 4 Dec 2018 13:47:17 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <20181204201432.GH18167@tassilo.jf.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-CA Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: rcampbell@nvidia.com, jhubbard@nvidia.com, Paul.Blinzer@amd.com, christian.koenig@amd.com, Philip.Yang@amd.com, felix.kuehling@amd.com, benh@kernel.crashing.org, aneesh.kumar@linux.ibm.com, balbirs@au1.ibm.com, haggaie@mellanox.com, dave.hansen@intel.com, ross.zwisler@linux.intel.com, rafael@kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, dan.j.williams@intel.com, jglisse@redhat.com, ak@linux.intel.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [RFC PATCH 02/14] mm/hms: heterogenenous memory system (HMS) documentation X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-12-04 1:14 p.m., Andi Kleen wrote: >> Also, in the same vein, I think it's wrong to have the API enumerate all >> the different memory available in the system. The API should simply > We need an enumeration API too, just to display to the user what they > have, and possibly for applications to size their buffers > (all we do with existing NUMA nodes) Yes, but I think my main concern is the conflation of the enumeration API and the binding API. An application doesn't want to walk through all the possible memory and types in the system just to get some memory that will work with a couple initiators (which it somehow has to map to actual resources, like fds). We also don't want userspace to police itself on which memory works with which initiator. Enumeration is definitely not the common use case. And if we create a new enumeration API now, it may make it difficult or impossible to unify these types of memory with the existing NUMA node hierarchies if/when this gets more integrated with the mm core. Logan