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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable 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 CC1DAC43219 for ; Thu, 25 Apr 2019 20:16:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CAA8820717 for ; Thu, 25 Apr 2019 20:16:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730957AbfDYUQ2 (ORCPT ); Thu, 25 Apr 2019 16:16:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41082 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726125AbfDYUQ2 (ORCPT ); Thu, 25 Apr 2019 16:16:28 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7846C8E581; Thu, 25 Apr 2019 20:16:27 +0000 (UTC) Received: from redhat.com (unknown [10.20.6.236]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CE9895D9CC; Thu, 25 Apr 2019 20:16:25 +0000 (UTC) Date: Thu, 25 Apr 2019 16:16:24 -0400 From: Jerome Glisse To: lsf-pc@lists.linux-foundation.org Cc: linux-mm@kvack.org, Dan Williams , Dave Hansen , Felix Kuehling , John Hubbard , Jonathan Cameron , Keith Busch , Mel Gorman , Michal Hocko , Paul Blinzer , linux-kernel@vger.kernel.org Subject: Re: [LSF/MM TOPIC] NUMA, memory hierarchy and device memory Message-ID: <20190425201623.GB6391@redhat.com> References: <20190118174512.GA3060@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190118174512.GA3060@redhat.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 25 Apr 2019 20:16:28 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I see that the schedule is not full yet for the mm track and i would really like to be able to have a discussion on this topic Schedule: https://docs.google.com/spreadsheets/d/1Z1pDL-XeUT1ZwMWrBL8T8q3vtSqZpLPgF3Bzu_jejfk/edit#gid=0 On Fri, Jan 18, 2019 at 12:45:13PM -0500, Jerome Glisse wrote: > Hi, i would like to discuss about NUMA API and its short comings when > it comes to memory hierarchy (from fast HBM, to slower persistent > memory through regular memory) and also device memory (which can have > its own hierarchy). > > I have proposed a patch to add a new memory topology model to the > kernel for application to be able to get that informations, it > also included a set of new API to bind/migrate process range [1]. > Note that this model also support device memory. > > So far device memory support is achieve through device specific ioctl > and this forbid some scenario like device memory interleaving accross > multiple devices for a range. It also make the whole userspace more > complex as program have to mix and match multiple device specific API > on top of NUMA API. > > While memory hierarchy can be more or less expose through the existing > NUMA API by creating node for non-regular memory [2], i do not see this > as a satisfying solution. Moreover such scheme does not work for device > memory that might not even be accessible by CPUs. > > > Hence i would like to discuss few points: > - What proof people wants to see this as problem we need to solve ? > - How to build concensus to move forward on this ? > - What kind of syscall API people would like to see ? > > People to discuss this topic: > Dan Williams > Dave Hansen > Felix Kuehling > John Hubbard > Jonathan Cameron > Keith Busch > Mel Gorman > Michal Hocko > Paul Blinzer > > Probably others, sorry if i miss anyone from previous discussions. > > Cheers, > Jérôme > > [1] https://lkml.org/lkml/2018/12/3/1072 > [2] https://lkml.org/lkml/2018/12/10/1112 >