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Tue, 10 Sep 2024 18:26:03 +0900 (KST) Received: from [107.122.11.51] (unknown [107.122.11.51]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20240910092559epsmtip21e15ace98c8e2bda39a2dbad69522f80~z182IcM510197501975epsmtip2l; Tue, 10 Sep 2024 09:25:59 +0000 (GMT) Message-ID: Date: Tue, 10 Sep 2024 14:55:58 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH v4 5/5] nvme: enable FDP support Content-Language: en-US To: Keith Busch Cc: axboe@kernel.dk, hch@lst.de, sagi@grimberg.me, martin.petersen@oracle.com, James.Bottomley@hansenpartnership.com, brauner@kernel.org, jack@suse.cz, jaegeuk@kernel.org, jlayton@kernel.org, chuck.lever@oracle.com, bvanassche@acm.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, gost.dev@samsung.com, vishak.g@samsung.com, javier.gonz@samsung.com, Nitesh Shetty , Hui Qi From: Kanchan Joshi In-Reply-To: Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA02Te0xTdxTHdx+0hVFzLa8fZBtd2SNgoJSVekHp3GzYZS4Gh0BituAdvTwC fdDbTpxLqKIyMcDEANIhrRQwgBuKhMeQBMsYMmCQIQM72+Eom0gcCFsmoLCWyxj/fc7J+Z5n DgfhnWQHcDKVWkqjJLMFLA+0rTf4zdBr2FRa+JT1JbzJVsLC53oXIbx8YRnB121/wPi9nk4Y b2jqg/HO+q/Z+FcV+TDuaDYg+I0SDj59f4mNL9c3svFSy88Q3m3dhf9U8x5+q3sAxY31M2z8 /EQHC7/avwbjbatGBP9mbh7FRwxV7H2+xNjdA8SI/QZKlJf+wCLGhnVES+M5FnGzNo/oMi3B RNc9PYt4MmNFieLWRogYMn3HJpZaXon3PJK1N4Mi5ZSGTylTVfJMZXqM4EBCyv6USEm4KFQU he8W8JWkgooRyD6ID43NzHaOK+B/SmbrnK54kqYFQulejUqnpfgZKlobI6DU8my1WB1Gkwpa p0wPU1LaaFF4eESkM/BoVkb/chtL3eSZe350ma2HTnkUQu4cgIlBa8EcqxDy4PCwLghcrbmL MMYiBEZbpt22jOqyGmcYZ0NSvw4z/k4IrDZc2VQ8hoDd2uTmysvFpOB5tx51CVDsdTDRe4hx 7wQDlQ7UxT7YJ2BlvApysZcz58SdecTFCOYHrA4j7GJvLAjYjJUbTSCYGQWPisxurpwsLBiM XtS50B2LBhfOHGakgaD9cdVGOwAzu4PLD6/AzJgyUDfdjjLsBR71t7IZDgBLf3azGM4CU79N bcZ8DjpuFrsx/DbQP5vcKIs4yzZ/K2Rq7QBFqw6YWQkXfHGWx0S/CuylM5tKP/DgUu0mE6C5 /nt4a1PdFxeQLyG+YdtWDNumN2wbx/B/ZROENkL+lJpWpFN0pFqkpI5tnTtVpWiBNn4hJK4D sk0thFkgmANZIMBBBN7cEqk9jceVk8c/ozSqFI0um6ItUKTzOheQAJ9UlfOZlNoUkTgqXCyR SMRRb0lEAj/u3JnLch6WTmqpLIpSU5r/dDDHPUAPF/FrM6JNtz3gyhz2eM2Hg++/VpFqNuV4 7RdGhvpOJyKZytv5J+IjZMWri4qQuOqRfcefNu9e6zPGkrRF+8vfpqDcPfNnf3VP9JUW+2PU scDFAfmh5GdlUqHu3QTzuI+DJqnTuuv5wbs4CUkVEfOZt+pGhx5U+x+U3RmOO7ocBj/sseZO KJJmV/4C92fLn58IMa69EHXYS2y+jj6VJmi8n9jqftyTY2jP66FnT5+C1Od2SB3J3KDYl6Vl oncC7dcGFiryFtKEicO8Urde2ZEXbQ3W9TH9P5aCWnPL74OKjwomgyYLjXYVKyZp9WRJ8seI 4g3P/IMBK8I+yaXBnb1DApTOIEUhiIYm/wVws0vWlAQAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrJIsWRmVeSWpSXmKPExsWy7bCSvO5qgQdpBvcm2VisvtvPZvH68CdG i2kffjJb/L/7nMni5oGdTBYrVx9lsti5bC27xezpzUwWT9bPYrbY2M9h8fjOZ3aLn8tWsVtM OnSN0WLvLW2LS4vcLfbsPcliMX/ZU3aL7us72CyWH//HZLHt93xmi3Wv37NYnJ81h91BzOPy FW+P8/c2snhMm3SKzePy2VKPTas62Tw2L6n32L3gM5PH7psNbB4fn95i8ejbsorR48yCI+we nzfJBfBEcdmkpOZklqUW6dslcGUc/7mNrWA1T0X3hZ/sDYxNXF2MHBwSAiYSy/4zdTFycQgJ bGeU+Dipn7GLkRMoLi7RfO0HO4QtLLHy33N2iKLXjBLTzv1iBknwCthJ/N3bwAIyiEVAVeL6 4UCIsKDEyZlPWEBsUYEkiT33G5lAbGGgXddPvAdrZQaaf+vJfLC4iICyxN35M1lB5jMLLGaR 2LRxGxvEsreMElM3XmADWcAmoClxYXIpiMkpYCUxsTUEYo6ZRNfWLkYIW15i+9s5zBMYhWYh OWMWknWzkLTMQtKygJFlFaNoakFxbnpucoGhXnFibnFpXrpecn7uJkZw7GsF7WBctv6v3iFG Jg7GQ4wSHMxKIrz9dvfShHhTEiurUovy44tKc1KLDzFKc7AoifMq53SmCAmkJ5akZqemFqQW wWSZODilGph2m7ya35ot5KP/YYb6hKd5wsctNNOaz+lnb2Fry96Rd13xnb5VcnLw+wM/z7v5 3A1z3HYjc+pNA5eOJH/2Lf/+52hUT+BcU2vYlu/xzWyv+SPpcot/k9LZpIzW3dgUfWfbllXV h7rkhSZe10q4duqRRJxgvS0nu9QnEcl7whOL5mpGvLyuUBRw0zzSXPl0RXffckP9/bebOL/e rT6/wu7y7efzNPfkbFqTGCkrfP69UVVQ/svtn79VXG+5kS/Bl5D3RatH21yzzcomI3WOTYtX Lc80q4NXXumcMO1dLn3yPI941ZwV7z+bO52333cieVOjY9+FBw1XHsg55LzT5Tq7YobzRu8X LM6zVcz99iqxFGckGmoxFxUnAgBTa/iJbAMAAA== X-CMS-MailID: 20240910092604epcas5p4d01dec7422c7990882f6453c52a78075 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20240826171430epcas5p3d8e34a266ced7b3ea0df2a11b83292ae References: <20240826170606.255718-1-joshi.k@samsung.com> <20240826170606.255718-6-joshi.k@samsung.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240910_022619_705881_56CCC777 X-CRM114-Status: GOOD ( 19.84 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 9/6/2024 9:34 PM, Keith Busch wrote: > On Mon, Aug 26, 2024 at 10:36:06PM +0530, Kanchan Joshi wrote: >> Flexible Data Placement (FDP), as ratified in TP 4146a, allows the host >> to control the placement of logical blocks so as to reduce the SSD WAF. >> >> Userspace can send the data placement information using the write hints. >> Fetch the placement-identifiers if the device supports FDP. >> >> The incoming placement hint is mapped to a placement-identifier, which >> in turn is set in the DSPEC field of the write command. >> >> Signed-off-by: Kanchan Joshi >> Signed-off-by: Nitesh Shetty >> Signed-off-by: Hui Qi > > I'm still fine with this nvme implementation. > > Acked-by: Keith Busch > > The reporting via fcntl looks okay to me, but I've never added anything > to that interface, so not sure if there's any problem using it for this. > The difference comes only in the fcntl interface (hint type/value pair rather than just value), otherwise it piggybacks on the same kernel infrastructure that ensures the hint is propagated fine. So I do not foresee problems. And FWIW, we have had precedents when a revamped fcntl was introduced to do what was not possible with the existing fcntl. Like: F_{GET/SET}OWN_EX over F_{GET/SET}OWN. Per-file hinting has its uses, particularly for buffered IO. But the current interface can only do data-lifetime hints. The revamped interface may come handy for other things too (e.g., KPIO).