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Received: from s0106a84e3fe8c3f3.cg.shawcable.net ([24.64.144.200] helo=[192.168.0.10]) by ale.deltatee.com with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1mVjNK-0008VW-LI; Wed, 29 Sep 2021 17:52:35 -0600 To: Jason Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Stephen Bates , Christoph Hellwig , Dan Williams , =?UTF-8?Q?Christian_K=c3=b6nig?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Jakowski Andrzej , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni References: <20210916234100.122368-1-logang@deltatee.com> <20210928200216.GW3544071@ziepe.ca> <06d75fcb-ce8b-30a5-db36-b6c108460d3d@deltatee.com> <20210929232147.GD3544071@ziepe.ca> <93f56919-03ee-8326-10ee-8fbd9078b8e0@deltatee.com> <20210929233624.GG3544071@ziepe.ca> From: Logan Gunthorpe Message-ID: <142badec-f6f5-e471-698e-8a386aae3c2b@deltatee.com> Date: Wed, 29 Sep 2021 17:52:32 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20210929233624.GG3544071@ziepe.ca> Content-Type: text/plain; charset=utf-8 Content-Language: en-CA Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 24.64.144.200 X-SA-Exim-Rcpt-To: ckulkarnilinux@gmail.com, martin.oliveira@eideticom.com, robin.murphy@arm.com, ira.weiny@intel.com, helgaas@kernel.org, jianxin.xiong@intel.com, dave.hansen@linux.intel.com, jason@jlekstrand.net, dave.b.minturn@intel.com, andrzej.jakowski@intel.com, daniel.vetter@ffwll.ch, willy@infradead.org, ddutile@redhat.com, jhubbard@nvidia.com, christian.koenig@amd.com, dan.j.williams@intel.com, hch@lst.de, sbates@raithlin.com, iommu@lists.linux-foundation.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, jgg@ziepe.ca X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v3 00/20] Userspace P2PDMA with O_DIRECT NVMe devices X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 01355B000809 X-Stat-Signature: qekuynbdkent7m99t5hfqg5m9qbea5c9 Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=deltatee.com header.s=20200525 header.b="BYOpvsO/"; dmarc=pass (policy=none) header.from=deltatee.com; spf=pass (imf24.hostedemail.com: domain of logang@deltatee.com designates 204.191.154.188 as permitted sender) smtp.mailfrom=logang@deltatee.com X-HE-Tag: 1632959566-528281 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2021-09-29 5:36 p.m., Jason Gunthorpe wrote: > On Wed, Sep 29, 2021 at 05:28:38PM -0600, Logan Gunthorpe wrote: >> >> >> On 2021-09-29 5:21 p.m., Jason Gunthorpe wrote: >>> On Wed, Sep 29, 2021 at 03:50:02PM -0600, Logan Gunthorpe wrote: >>>> >>>> >>>> On 2021-09-28 2:02 p.m., Jason Gunthorpe wrote: >>>>> On Thu, Sep 16, 2021 at 05:40:40PM -0600, Logan Gunthorpe wrote: >>>>>> Hi, >>>>>> >>>>>> This patchset continues my work to add userspace P2PDMA access using >>>>>> O_DIRECT NVMe devices. My last posting[1] just included the first 13 >>>>>> patches in this series, but the early P2PDMA cleanup and map_sg error >>>>>> changes from that series have been merged into v5.15-rc1. To address >>>>>> concerns that that series did not add any new functionality, I've added >>>>>> back the userspcae functionality from the original RFC[2] (but improved >>>>>> based on the original feedback). >>>>> >>>>> I really think this is the best series yet, it really looks nice >>>>> overall. I know the sg flag was a bit of a debate at the start, but it >>>>> serves an undeniable purpose and the resulting standard DMA APIs 'just >>>>> working' is really clean. >>>> >>>> Actually, so far, nobody has said anything negative about using the SG flag. >>>> >>>>> There is more possible here, we could also pass the new GUP flag in the >>>>> ib_umem code.. >>>> >>>> Yes, that would be very useful. >>> >>> You might actually prefer to do that then the bio changes to get the >>> infrastructur merged as it seems less "core" >> >> I'm a little bit more concerned about my patch set growing too large. >> It's already at 20 patches and I think I'll need to add a couple more >> based on the feedback you've already provided. So I'm leaning toward >> pushing more functionality as future work. > > I mean you could postpone the three block related patches and use a > single ib_umem patch instead as the consumer. I think that's not a very compelling use case given the only provider of these VMAs is an NVMe block device. My patch set enables a real world use (copying data between NVMe devices P2P through the CMB with O_DIRECT). Being able to read or write a CMB with RDMA and only RDMA is not very compelling. Logan