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Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.13.1 Subject: Re: [RFC PATCH 0/4] Read/Write with meta buffer Content-Language: en-US To: Pavel Begunkov , martin.petersen@oracle.com, axboe@kernel.dk, kbusch@kernel.org, hch@lst.de Cc: io-uring@vger.kernel.org, linux-block@vger.kernel.org, anuj1072538@gmail.com From: Kanchan Joshi In-Reply-To: <0c8f64b3-8ca7-4424-ac50-08222f6401c1@gmail.com> Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprPJsWRmVeSWpSXmKPExsWy7bCmlm73Sq00gxWnuC0+fv3NYjFn1TZG i9V3+9ksVq4+ymTxrvUci8WkQ9cYLfbe0rZYfvwfkwOHx85Zd9k9Lp8t9di0qpPNY/fNBjaP j09vsXh83iQXwBaVbZORmpiSWqSQmpecn5KZl26r5B0c7xxvamZgqGtoaWGupJCXmJtqq+Ti E6DrlpkDdI6SQlliTilQKCCxuFhJ386mKL+0JFUhI7+4xFYptSAlp8CkQK84Mbe4NC9dLy+1 xMrQwMDIFKgwITvj6ZZrjAV72Sv+fv7J0sD4h7WLkZNDQsBE4nXHeyCbi0NIYA+jxI3Tu9kh nE+MEt+nzGaGcL4xSvT/PALX8vHpQiYQW0hgL6PEzetlEPZbRolpV2tAbF4BO4meKZPB6lkE VCW2tfxigogLSpyc+YQFxBYVSJb42XWArYuRg0NYwELi2iVHkDCzgLjErSfzmUDCIgKVEqt/ WEKEgyRevmkBq2YT0JS4MLkUxOQUsJU4s8sHokJeYvvbOWAHSwhM5ZDYOfcHG8TBLhKv1+5h h7CFJV4d3wJlS0m87G+DspMlLs08xwRhl0g83nMQyraXaD3Vzwyyixlo7fpd+hC7+CR6fz8B O1JCgFeio00IolpR4t6kp9BgEpd4OGMJlO0h0fBqAhMkLA8wSrS1LmebwKgwCylIZiH5fRaS d2YhbF7AyLKKUSq1oDg3PTXZtMBQNy+1HB7Zyfm5mxjBKVUrYAfj6g1/9Q4xMnEwHmKU4GBW EuG9+VEjTYg3JbGyKrUoP76oNCe1+BCjKTByJjJLiSbnA5N6Xkm8oYmlgYmZmZmJpbGZoZI4 7+vWuSlCAumJJanZqakFqUUwfUwcnFINTBXi+4ri35buOdmw4qW66Zl0UX23zZ/L7k8yOnDq xNf3h3OXlzmePP/5unXZZNdZjcrnqy/t0Fiu+9jJ/HVzfJvl3p0THbzC2wufn+iblufWu8Kb 4+S7TZuld8ib/xNtrOQKcwud/WdTnWJPx/2YErGrGpXP77MlWkfWa+nM/TtVclXS31TpX6We HwuCFrobV77V++S5cNPit9KXos68eVlVXbZ3heSFwzO9fneWdT/rn9u4+qmG0aKQrUc0d0W9 ynG2Xcz+6fwcHq85SoquWmt2cC/omagfJMwhJO/MwBhVfCgs6b5+zpYjzZe/VNntvFUo6Ja8 WHNjqmrJtfwG9lsZ+ee3bN5zNSPg8y8zYyWW4oxEQy3mouJEAEVidXcyBAAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrDLMWRmVeSWpSXmKPExsWy7bCSnG7XSq00g13HmC0+fv3NYjFn1TZG i9V3+9ksVq4+ymTxrvUci8WkQ9cYLfbe0rZYfvwfkwOHx85Zd9k9Lp8t9di0qpPNY/fNBjaP j09vsXh83iQXwBbFZZOSmpNZllqkb5fAlfF0yzXGgr3sFX8//2RpYPzD2sXIySEhYCLx8elC pi5GLg4hgd2MErNfLmSBSIhLNF/7wQ5hC0us/PcczBYSeM0osfRhNYjNK2An0TNlMtggFgFV iW0tv5gg4oISJ2c+AZsjKpAs8fLPRKBeDg5hAQuJa5ccQcLMQONvPZkPVi4iUCnx6X4jE0Q8 SGLW01ksEPccYJT4dG8bK0gvm4CmxIXJpSAmp4CtxJldPhDlZhJdW7sYIWx5ie1v5zBPYBSa heSIWUi2zULSMgtJywJGllWMkqkFxbnpucWGBYZ5qeV6xYm5xaV56XrJ+bmbGMERpKW5g3H7 qg96hxiZOBgPMUpwMCuJ8N78qJEmxJuSWFmVWpQfX1Sak1p8iFGag0VJnFf8RW+KkEB6Yklq dmpqQWoRTJaJg1Oqgclf5XVqsG7vJLZ81r5OpVca/9wXcMj7+WS5L2bx3tRTvmk3w+bHra3m YjqXHlz1zbgXMt9lg+Ubtr7zk1bpihfMmGr0MSL/RABLnTGXaN407UWxe+xeC+zj/v3Y7M5k 7++i2cqmTjWnNQo+3exY9yO1IPi2RlzBonq9HxqnJ8t2X2h3XHL/zkGfNtWMnK0aQqn5Lxdo /bpw2qNSZcM84zkTTj/v+r7kwIWyix5zMzLt67c+NGN+POuM0runt3blqSg9TgmL+j9plfnn Cu3poT3C5xdGOS+0jTpbv2Xj4+8/Lr1xinx/levRprJ1rEwske+eShZN7IkU9/1xg6GKY5I+ /4OmTsbIN9v0ah8WzlNiKc5INNRiLipOBAC8C+31DwMAAA== X-CMS-MailID: 20240425190546epcas5p4c7f30b1c106e19da80290ad6a26e8620 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20240322185729epcas5p350c5054b5b519a6aa9d1b35ba3709563 References: <20240322185023.131697-1-joshi.k@samsung.com> <0c8f64b3-8ca7-4424-ac50-08222f6401c1@gmail.com> On 4/7/2024 3:00 AM, Pavel Begunkov wrote: > On 3/22/24 18:50, Kanchan Joshi wrote: >> This patchset is aimed at getting the feedback on a new io_uring >> interface that userspace can use to exchange meta buffer along with >> read/write. >> >> Two new opcodes for that: IORING_OP_READ_META and IORING_OP_WRITE_META. >> The leftover space in the SQE is used to send meta buffer pointer >> and its length. Patch #2 for this. > > I do remember there were back and forth design discussions about that > back when some other guy attempted to implement it, but have you tried > to do it not as a separate opcode? Did not try that in the first cut, thinking it would help in not touching the hot (non-meta) io path. But open to this. > It reads like all read/write opcodes might benefit from it, and it'd > be unfortunate to then be adding IORING_OP_READ_META_FIXED and > multiplicatively all other variants. Right, that's a good point.