From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f49.google.com (mail-wg0-f49.google.com [74.125.82.49]) by kanga.kvack.org (Postfix) with ESMTP id C17B6800CA for ; Fri, 7 Nov 2014 16:36:46 -0500 (EST) Received: by mail-wg0-f49.google.com with SMTP id x13so4705724wgg.36 for ; Fri, 07 Nov 2014 13:36:46 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id dc10si9441219wjc.60.2014.11.07.13.36.45 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 07 Nov 2014 13:36:45 -0800 (PST) Message-ID: <545D3B3D.50907@redhat.com> Date: Fri, 07 Nov 2014 16:35:57 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH 4/5] hmm: heterogeneous memory management v6 References: <1415047353-29160-1-git-send-email-j.glisse@gmail.com> <1415047353-29160-5-git-send-email-j.glisse@gmail.com> In-Reply-To: <1415047353-29160-5-git-send-email-j.glisse@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: j.glisse@gmail.com, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , joro@8bytes.org, Mel Gorman , "H. Peter Anvin" , Peter Zijlstra , Andrea Arcangeli , Johannes Weiner , Larry Woodman , Dave Airlie , Brendan Conoboy , Joe Donohue , Duncan Poole , Sherry Cheung , Subhash Gutti , John Hubbard , Mark Hairgrove , Lucien Dunning , Cameron Buschardt , Arvind Gopalakrishnan , Shachar Raindel , Liran Liss , Roland Dreier , Ben Sander , Greg Stoner , John Bridgman , Michael Mantor , Paul Blinzer , Laurent Morichetti , Alexander Deucher , Oded Gabbay , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jatin Kumar -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 11/03/2014 03:42 PM, j.glisse@gmail.com wrote: > From: JA(C)rA'me Glisse > > Motivation: > > Heterogeneous memory management is intended to allow a device to > transparently access a process address space without having to lock > pages of the process or take references on them. In other word > mirroring a process address space while allowing the regular memory > management event such as page reclamation or page migration, to > happen seamlessly. > > Recent years have seen a surge into the number of specialized > devices that are part of a computer platform (from desktop to > phone). So far each of those devices have operated on there own > private address space that is not link or expose to the process > address space that is using them. This separation often leads to > multiple memory copy happening between the device owned memory and > the process memory. This of course is both a waste of cpu cycle and > memory. > > Over the last few years most of those devices have gained a full > mmu allowing them to support multiple page table, page fault and > other features that are found inside cpu mmu. There is now a strong > incentive to start leveraging capabilities of such devices and to > start sharing process address to avoid any unnecessary memory copy > as well as simplifying the programming model of those devices by > sharing an unique and common address space with the process that > use them. > > The aim of the heterogeneous memory management is to provide a > common API that can be use by any such devices in order to mirror > process address. The hmm code provide an unique entry point and > interface itself with the core mm code of the linux kernel avoiding > duplicate implementation and shielding device driver code from core > mm code. Acked-by: Rik van Riel - -- All rights reversed -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJUXTs9AAoJEM553pKExN6DhSYIAI41vr6c/vVdIg2m6Wq3DiSS KtBTUX5/cFmvh9Zd3S422ZwzJQ6ZZLGsNuh2LajLqR0dhDKkwxS7FWFSdifcAfq2 B/Xq8JyeW98Fa0OP0V4uqMuo1FMvlXFZsDijFefxo5F2T/H6XyRI2M+f4w5w9iZa 3EvUaFHoG+mCjoR+ANuxwR9J048wWF626R6CHPOvvIKDNRVr+LADvLMBXmbnrYJs 643mmjhNT+EdPQbxBVszsUbBo/mGicRBuW+t3XkWy1g+hsa4AewhHnOuSHDr13zM YBFjeGP1TbOQxtkiJetsAE4pKxSlJDoscp7vbJjYzLz3Kk2Fag3r1kpSU8S8stI= =ucI+ -----END PGP SIGNATURE----- -- 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