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_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 10016C43334 for ; Wed, 5 Sep 2018 19:33:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B24D72077C for ; Wed, 5 Sep 2018 19:33:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B24D72077C 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 S1727769AbeIFAFa (ORCPT ); Wed, 5 Sep 2018 20:05:30 -0400 Received: from ale.deltatee.com ([207.54.116.67]:53516 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727267AbeIFAFa (ORCPT ); Wed, 5 Sep 2018 20:05:30 -0400 Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtp (Exim 4.89) (envelope-from ) id 1fxdYN-0004yR-Rs; Wed, 05 Sep 2018 13:33:28 -0600 To: Jens Axboe , Christoph Hellwig Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, linux-nvdimm@lists.01.org, linux-block@vger.kernel.org, Stephen Bates , Keith Busch , Sagi Grimberg , Bjorn Helgaas , Jason Gunthorpe , Max Gurtovoy , Dan Williams , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Benjamin Herrenschmidt , Alex Williamson , =?UTF-8?Q?Christian_K=c3=b6nig?= References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> <20180901082812.GB670@lst.de> <5f79c012-c6e1-56bb-62fd-0689181fb2c9@deltatee.com> <59b28977-8f2a-6228-2050-03fae6bdbedd@kernel.dk> From: Logan Gunthorpe Message-ID: <1b4283da-44df-4a02-3167-e295243cef78@deltatee.com> Date: Wed, 5 Sep 2018 13:33:23 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <59b28977-8f2a-6228-2050-03fae6bdbedd@kernel.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: christian.koenig@amd.com, alex.williamson@redhat.com, benh@kernel.crashing.org, jglisse@redhat.com, dan.j.williams@intel.com, maxg@mellanox.com, jgg@mellanox.com, bhelgaas@google.com, sagi@grimberg.me, keith.busch@intel.com, sbates@raithlin.com, linux-block@vger.kernel.org, linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, hch@lst.de, axboe@kernel.dk X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests 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 05/09/18 01:26 PM, Jens Axboe wrote: > On 9/3/18 4:26 PM, Logan Gunthorpe wrote: >> I personally agree with Christoph. But if there's consensus in the other >> direction or this is a real blocker moving this forward, I can remove it >> for the next version. > > It's a simple branch because the check isn't exhaustive. It just checks > the first page. At that point you may as well just require the caller to > flag the bio/rq as being P2P, and then do a check for P2P compatibility > with the queue. Hmm, we had something like that in v4[1] but it just seemed redundant to create a flag when the information was already in the bio and kind of ugly for the caller to check for, then set, the flag. I'm not _that_ averse to going back to that though... Logan [1] https://lore.kernel.org/lkml/20180423233046.21476-8-logang@deltatee.com/T/#u