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Tue, 12 Nov 2024 14:00:22 +0000 (GMT) Received: from epsmgms1p1new.samsung.com (unknown [182.195.42.41]) by epsmtrp2.samsung.com (KnoxPortal) with ESMTP id 20241112140022epsmtrp26ef2ac422dfa4f075d1bb656973e7bbd~HPVZXxwZl0763707637epsmtrp2b; Tue, 12 Nov 2024 14:00:22 +0000 (GMT) X-AuditID: b6c32a44-6dbff7000000217e-fc-67338300c3af Received: from epsmtip2.samsung.com ( [182.195.34.31]) by epsmgms1p1new.samsung.com (Symantec Messaging Gateway) with SMTP id A5.00.35203.67F53376; Tue, 12 Nov 2024 23:00:22 +0900 (KST) Received: from ubuntu (unknown [107.99.41.245]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20241112140020epsmtip2d85a84822d57f03f02e4212268895bda~HPVXfWIw20570005700epsmtip2t; Tue, 12 Nov 2024 14:00:20 +0000 (GMT) Date: Tue, 12 Nov 2024 19:22:33 +0530 From: Nitesh Shetty To: Bart Van Assche Cc: Javier Gonzalez , Matthew Wilcox , Keith Busch , Christoph Hellwig , Keith Busch , "linux-block@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "linux-scsi@vger.kernel.org" , "io-uring@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "joshi.k@samsung.com" Subject: Re: [PATCHv10 0/9] write hints with nvme fdp, scsi streams Message-ID: <20241112135233.2iwgwe443rnuivyb@ubuntu> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrAJsWRmVeSWpSXmKPExsWy7bCmhi5Ds3G6wdVV/BbTPvxktli5+iiT xbvWcywWj+98Zrc4+v8tm8WkQ9cYLc5cXchisfeWtsWevSdZLOYve8pu0X19B5vF7x9z2Bx4 PC5f8fbYvELLY9OqTjaPzUvqPXbfbGDzOHexwqNvyypGj8+b5AI4orJtMlITU1KLFFLzkvNT MvPSbZW8g+Od403NDAx1DS0tzJUU8hJzU22VXHwCdN0yc4AuVVIoS8wpBQoFJBYXK+nb2RTl l5akKmTkF5fYKqUWpOQUmBToFSfmFpfmpevlpZZYGRoYGJkCFSZkZ0x/8p+x4L5Exb6Pz9ka GH8KdzFyckgImEhcm/eYsYuRi0NIYDejxIQHLawgCSGBT4wS2y8mQCS+MUr0vb/P1sXIAdbR 2R8PEd/LKHFw2lM2COcJo0TrpweMIN0sAqoShxZPZwJpYBPQljj9nwMkLCKgIfHtwXIWkHpm gYUsEr8/3mQBSQgLOEv0zL0L1ssLtODK6kNMELagxMmZT8BqOAWsJRrf/meDOHslh8TbhaEQ tovExPanjBC2sMSr41vYIWwpic/v9kLVl0usnLIC7FAJgRZGiVnXZ0E12Eu0nupnBjmUWSBD 4twfd4iwrMTUU+vAbmAW4JPo/f2ECSLOK7FjHoytLLFm/QKo+ZIS1743QtkeEvO//oQG6XVm ie53ExknMMrNQvLPLIR1s8BWWEl0fmhihQhLSyz/xwFhakqs36W/gJF1FaNkakFxbnpqsmmB YV5qOTyKk/NzNzGCk66Wyw7GG/P/6R1iZOJgPMQowcGsJMJ7ytk4XYg3JbGyKrUoP76oNCe1 +BCjKTB6JjJLiSbnA9N+Xkm8oYmlgYmZmZmJpbGZoZI47+vWuSlCAumJJanZqakFqUUwfUwc nFINTDd9J97U+ZMl7hUumGLdymrNOcm5umd5W94E0ZXK3u6M1yRn1626r59TY/Hs5uK1HAc6 b82b/4OJb+bL05Lb2fkbA3L2BDaWLpxaWDLxZXCKf4OpxZ79q+Wecuzy5JubvXq17dWZlctf KWWofL4Qr5Y56+OUgxVnIm6fDM6TUNhRtdg7IdA7VWWDwdp2BXE9JfabSsePOOxxeiHWZ7kr 9+qMjQJBNYX2U+8tnBS4+5PDjHJGi2v2XbbsX5mP2th+kjmwrfxanLAvB9urhx5N94/2VX3+ zaR1KdTVfY8q3zQGjwmFlRLdeyyERd9duKW5c4nZ9GAhA99LP+dv+WV12rdl4Y6oyzqePAmC aq4/lViKMxINtZiLihMBYi0trUMEAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrMLMWRmVeSWpSXmKPExsWy7bCSvG5ZvHG6welFahbTPvxktli5+iiT xbvWcywWj+98Zrc4+v8tm8WkQ9cYLc5cXchisfeWtsWevSdZLOYve8pu0X19B5vF7x9z2Bx4 PC5f8fbYvELLY9OqTjaPzUvqPXbfbGDzOHexwqNvyypGj8+b5AI4orhsUlJzMstSi/TtErgy mtaeYC+YKFaxfspxxgbGo4JdjBwcEgImEp398V2MXBxCArsZJRace8jaxcgJFJeUWPb3CDOE LSyx8t9zdoiiR4wSkz6vZANJsAioShxaPJ0JZBCbgLbE6f8cIGERAQ2Jbw+Ws4DUMwssZZG4 MPc42CBhAWeJnrl3GUFsXqDFV1YfYgKxhQRuM0v8+lgLEReUODnzCQuIzSxgJjFv80NmkPnM AtISy/+BzecUsJZofPufbQKjwCwkHbOQdMxC6FjAyLyKUTK1oDg3PbfYsMAwL7Vcrzgxt7g0 L10vOT93EyM4XrQ0dzBuX/VB7xAjEwfjIUYJDmYlEd5TzsbpQrwpiZVVqUX58UWlOanFhxil OViUxHnFX/SmCAmkJ5akZqemFqQWwWSZODilGpi4L7Y3lwYtWnEmZyVjUIpRwvSP2YdOd79d MEePUVHrV+qjrredH3UFXh7oNZzslDH/0n2VW6fK/vvJFUje27fj2bdX1YeTLlyKnq6fOzFZ 7trdBfPXCG3lfH5264dnVuuLeqYdqF0TsnB93fuZT21kZvd9X7lpCa9ktlDoAk3rfy+NHjEI KzdenyN5uuHpYn85M8ZTd3li7mhp9Ab1Ggp0ZSy4s+Boy/+q2V89mPj9J31aY7FKYM7lr/t3 hVYt+3am81kO+66Fz4NzzI01fA84/P/h4qj+K21Xw1tbZqkv53lqdtz5NH9Zsc6qiU6Te0tY TgadmLDhbeyT8zfeT92db7C1xtpBaam9F9PligP6TUosxRmJhlrMRcWJADV7k30GAwAA X-CMS-MailID: 20241112140022epcas5p149b2709709e7a52109dfca99cefc4663 X-Msg-Generator: CA Content-Type: multipart/mixed; boundary="----w5-2f3KIOrSunQhSxAIo7Dy_B_SBAQB3Xz8aCSUoiMSFB8w5=_c2979_" X-Sendblock-Type: REQ_APPROVE CMS-TYPE: 105P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20241108165444eucas1p183f631e2710142fbbc7dee9300baf77a References: <20241105155014.GA7310@lst.de> <20241108141852.GA6578@lst.de> <2b5a365a-215a-48de-acb1-b846a4f24680@acm.org> <20241111093154.zbsp42gfiv2enb5a@ArmHalley.local> ------w5-2f3KIOrSunQhSxAIo7Dy_B_SBAQB3Xz8aCSUoiMSFB8w5=_c2979_ Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Disposition: inline On 11/11/24 09:45AM, Bart Van Assche wrote: >On 11/11/24 1:31 AM, Javier Gonzalez wrote: >>On 08.11.2024 10:51, Bart Van Assche wrote: >>>On 11/8/24 9:43 AM, Javier Gonzalez wrote: >>>>If there is an interest, we can re-spin this again... >>> >>>I'm interested. Work is ongoing in JEDEC on support for copy offloading >>>for UFS devices. This work involves standardizing which SCSI copy >>>offloading features should be supported and which features are not >>>required. Implementations are expected to be available soon. >> >>Do you have any specific blockers on the last series? I know you have >>left comments in many of the patches already, but I think we are all a >>bit confused on where we are ATM. > >Nobody replied to this question that was raised 4 months ago: >https://lore.kernel.org/linux-block/4c7f30af-9fbc-4f19-8f48-ad741aa557c4@acm.org/ > >I think we need to agree about the answer to that question before we can >continue with implementing copy offloading. > Yes, even I feel the same. Blocker with copy has been how we should plumb things in block layer. A couple of approaches we tried in the past[1]. Restating for reference, 1.payload based approach: a. Based on Mikulas patch, here a common payload is used for both source and destination bio. b. Initially we send source bio, upon reaching driver we update payload and complete the bio. c. Send destination bio, in driver layer we recover the source info from the payload and send the copy command to device. Drawback: Request payload contains IO information rather than data. Based on past experience Christoph and Bart suggested not a good way forward. Alternate suggestion from Christoph was to used separate BIOs for src and destination and match them using token/id. As Bart pointed, I find it hard how to match when the IO split happens. 2. Plug based approach: a. Take a plug, send destination bio, form request and wait for src bio b. send source bio, merge with destination bio c. Upon release of plug send request down to driver. Drawback: Doesn't work for stacked devices which has async submission. Bart suggested this is not good solution overall. Alternate suggestion was to use list based approach. But we observed lifetime management problems, especially in failure handling. 3. Single bio approach: a. Use single bio to represent both src and dst info. b. Use abnormal IO handling similar to discard. Drawback: Christoph pointed out that, this will have issue of payload containing information for both IO stack and wire. I am really torn on how to proceed further ? -- Nitesh Shetty [1] https://lore.kernel.org/linux-block/20240624103212.2donuac5apwwqaor@nj.shetty@samsung.com/ ------w5-2f3KIOrSunQhSxAIo7Dy_B_SBAQB3Xz8aCSUoiMSFB8w5=_c2979_ Content-Type: text/plain; charset="utf-8" ------w5-2f3KIOrSunQhSxAIo7Dy_B_SBAQB3Xz8aCSUoiMSFB8w5=_c2979_--