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,USER_AGENT_MUTT 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 0E65DC43381 for ; Tue, 19 Mar 2019 22:24:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D4F482175B for ; Tue, 19 Mar 2019 22:24:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727177AbfCSWYu (ORCPT ); Tue, 19 Mar 2019 18:24:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60782 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725958AbfCSWYu (ORCPT ); Tue, 19 Mar 2019 18:24:50 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DE214307EA90; Tue, 19 Mar 2019 22:24:49 +0000 (UTC) Received: from redhat.com (ovpn-120-246.rdu2.redhat.com [10.10.120.246]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C2E2B60148; Tue, 19 Mar 2019 22:24:47 +0000 (UTC) Date: Tue, 19 Mar 2019 18:24:45 -0400 From: Jerome Glisse To: Ira Weiny Cc: Dan Williams , Andrew Morton , Linux MM , Linux Kernel Mailing List , Felix Kuehling , Christian =?iso-8859-1?Q?K=F6nig?= , Ralph Campbell , John Hubbard , Jason Gunthorpe , Alex Deucher Subject: Re: [PATCH 00/10] HMM updates for 5.1 Message-ID: <20190319222445.GD3096@redhat.com> References: <20190319094007.a47ce9222b5faacec3e96da4@linux-foundation.org> <20190319165802.GA3656@redhat.com> <20190319101249.d2076f4bacbef948055ae758@linux-foundation.org> <20190319171847.GC3656@redhat.com> <20190319174552.GA3769@redhat.com> <20190319190528.GA4012@redhat.com> <20190319141826.GJ7485@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190319141826.GJ7485@iweiny-DESK2.sc.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Tue, 19 Mar 2019 22:24:50 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 19, 2019 at 07:18:26AM -0700, Ira Weiny wrote: > On Tue, Mar 19, 2019 at 12:13:40PM -0700, Dan Williams wrote: > > On Tue, Mar 19, 2019 at 12:05 PM Jerome Glisse wrote: > > > > > > On Tue, Mar 19, 2019 at 11:42:00AM -0700, Dan Williams wrote: > > > > On Tue, Mar 19, 2019 at 10:45 AM Jerome Glisse wrote: > > > > > > > > > > On Tue, Mar 19, 2019 at 10:33:57AM -0700, Dan Williams wrote: > > > > > > On Tue, Mar 19, 2019 at 10:19 AM Jerome Glisse wrote: > > > > > > > > > > > > > > On Tue, Mar 19, 2019 at 10:12:49AM -0700, Andrew Morton wrote: > > > > > > > > On Tue, 19 Mar 2019 12:58:02 -0400 Jerome Glisse wrote: > > [snip] > > > > > > > Right now i am trying to unify driver for device that have can support > > > the mmu notifier approach through HMM. Unify to a superset of driver > > > that can not abide by mmu notifier is on my todo list like i said but > > > it comes after. I do not want to make the big jump in just one go. So > > > i doing thing under HMM and thus in HMM namespace, but once i tackle > > > the larger set i will move to generic namespace what make sense. > > > > > > This exact approach did happen several time already in the kernel. In > > > the GPU sub-system we did it several time. First do something for couple > > > devices that are very similar then grow to a bigger set of devices and > > > generalise along the way. > > > > > > So i do not see what is the problem of me repeating that same pattern > > > here again. Do something for a smaller set before tackling it on for > > > a bigger set. > > > > All of that is fine, but when I asked about the ultimate trajectory > > that replaces hmm_range_dma_map() with an updated / HMM-aware GUP > > implementation, the response was that hmm_range_dma_map() is here to > > stay. The issue is not with forking off a small side effort, it's the > > plan to absorb that capability into a common implementation across > > non-HMM drivers where possible. > > Just to get on the record in this thread. > > +1 > > I think having an interface which handles the MMU notifier stuff for drivers is > awesome but we need to agree that the trajectory is to help more drivers if > possible. > Yes and i want to get there step by step not just in one giant leap. It seems Dan would like to see this all one step and i believe this is too risky and make the patchset much bigger and harder to review. Cheers, Jérôme