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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 4DD82C43613 for ; Thu, 20 Jun 2019 23:43:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2BFEB2070B for ; Thu, 20 Jun 2019 23:43:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726151AbfFTXnJ (ORCPT ); Thu, 20 Jun 2019 19:43:09 -0400 Received: from ale.deltatee.com ([207.54.116.67]:39490 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725886AbfFTXnG (ORCPT ); Thu, 20 Jun 2019 19:43:06 -0400 Received: from s01061831bf6ec98c.cg.shawcable.net ([68.147.80.180] helo=[192.168.6.132]) by ale.deltatee.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1he6hj-0001kp-Hh; Thu, 20 Jun 2019 17:42:56 -0600 To: Dan Williams Cc: Linux Kernel Mailing List , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, linux-rdma , Jens Axboe , Christoph Hellwig , Bjorn Helgaas , Sagi Grimberg , Keith Busch , Jason Gunthorpe , Stephen Bates References: <20190620161240.22738-1-logang@deltatee.com> <91eba9a0-27b4-08b4-7c12-86e24e1bfe85@deltatee.com> From: Logan Gunthorpe Message-ID: <3379917c-0ebc-0019-a71c-12248f4668ee@deltatee.com> Date: Thu, 20 Jun 2019 17:42:50 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 68.147.80.180 X-SA-Exim-Rcpt-To: sbates@raithlin.com, jgg@ziepe.ca, kbusch@kernel.org, sagi@grimberg.me, bhelgaas@google.com, hch@lst.de, axboe@kernel.dk, linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, dan.j.williams@intel.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [RFC PATCH 00/28] Removing struct page from P2PDMA 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 2019-06-20 5:40 p.m., Dan Williams wrote: > This seems to be the most salient point. I was missing the fact that > this replaces custom hacks and "special" pages with an explicit "just > pass this pre-mapped address down the stack". It's functionality that > might plausibly be used outside of p2p, as long as the driver can > assert that it never needs to touch the data with the cpu before > handing it off to a dma-engine. Yup, that's a good way to put it. If I resend this patchset, I'll include wording like yours in the cover letter. Logan