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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?bf8nVLjv2Y0KTEyu1HvHTvoM/SyVBx3Pz17eyZFGGAshA07RK91OGp/s2Bur?= =?us-ascii?Q?BVkl8xvcAZoAEC75QwHOCYO4R1Vq/U9vxjiOE6rx2EN+7AWE6OPOxiLuQtu9?= =?us-ascii?Q?zI4a8H2J46+EVcV/q6mNH/7QjdHUIYP8+fIOHp6dHaS4aUumNvO6JphiclwL?= =?us-ascii?Q?vE4Jgd41ydtoEDBKZMMT7oz0s9UJ0kUM9aTDz8KYm0z1dGJt9/8ccv9nbjs7?= =?us-ascii?Q?Bw833ATepqnmX4eDNFbfJnv4SuE6KOvSc+qriSP7J7dxaB0DwwvzlqexvoG5?= =?us-ascii?Q?o1USGslcZ1GfTtdsJt7hxyqkdH2BDsQu2RLD/lZEi82W61cMY08yB6qnDA6n?= =?us-ascii?Q?gzdIOfybknADF94nWTVuChF0Rxd5F9ihMMAcsSpryAUjkHBcxm0Da35YBCI8?= =?us-ascii?Q?q40T1pk2/TgfX2nzsyI3ZUjy+RmD3ungMGxyz+DvzEQ/LZSv43eAkFgK9cfS?= =?us-ascii?Q?a0BJt9Gfiipv9oXr/2qtx7sKYS1pgb84zbfXK0rPAGq6pCr28efSUzLYyGag?= =?us-ascii?Q?XJ5G23Ke14zUrWfJPUF+MfqPC3EMiihNwDghFVEQiAUmaVGl5GnV6HWO0Rpt?= =?us-ascii?Q?7yrpC54CppO16qV4dNE8XnMREcywRQJur0OSrL+nf2vAYYxkyPy+z+FBlvDz?= =?us-ascii?Q?76ppDI/aaezILWBTCP644taO/J10sywT4De96emPpGCYPh9VN0fzMRo98R0D?= =?us-ascii?Q?l0SPshgVQso/bwniBVmY7SZaIVwS6e7abq4EZIIr90exHuIrdt9ic7oTFwNO?= =?us-ascii?Q?pMvsEaNI4bv94iFkjJ0SgkJ44MTsKoN1HhZY3ktlBUVIqKQpWx8lnHwuEJrR?= =?us-ascii?Q?/DM7+XcJCQkgl3IiYAMPgnKka5hCb/RlA8MaeDoEK8fkWrnCXGAJA1kK3Jdx?= =?us-ascii?Q?tsNSVnpQGIEjFlJPcO8VpHuqEnqRkiAZisVVjFIDkF4Mod6/FuVOB7EMCz4Q?= =?us-ascii?Q?duzehRq2owioPzIhR2OvXcCbz0JqS4oRwPX5shKHNcB5YcZYHdGZasndhMgI?= =?us-ascii?Q?l4QoZRZCs+IYK4HC3Xan3ubRmtXeh3W+6pXZ5o4m1+QhNaM6VYuLAIte6KnD?= =?us-ascii?Q?PA/MigGkWkAgnjgTgK9VVGP/d0S4CfA7hf7pjxqjJCI3OzRcwyBvNNPxt1b7?= =?us-ascii?Q?tUgw5/YAV+0cRoP/3wDbz6FVzjO1sGHsP8ZLZORKMy8RQ4eVB6G3+aUsJXxK?= =?us-ascii?Q?tG5KnxzzkajGMyXOjtIpU130cZysdGiQ7gXZNEVYLlARvGuSU1QQf8LE4DIy?= =?us-ascii?Q?YFl3ym0GchcuTLutk8JCIeJm616BFyQIfL9tFbMC+2DhWg9FmHaih254Hx7B?= =?us-ascii?Q?VVngbgxNPF49C0iszcHaFCe6Q1nL36rREsXk1QbFBoxXqt2HzZ2woCIJsMkG?= =?us-ascii?Q?H3VpVcE05w1Ja0BWCCIjYmgW7/uTKHnqdLUlSdMCqrbvtT41cgMzcgST+X7B?= =?us-ascii?Q?mAzWfVaQu1uaP4kvVyZvgIjxB5FUgGehmG6cIIXYW8JOCVrc75/R1vFyWCMK?= =?us-ascii?Q?1L5NOSOLB+YcIaqOcCtUKvKNy2uasm6vn6nxQm9LRj3kI30yPusvWLdV/wFv?= =?us-ascii?Q?GoxEKPvNf/W0Vpc0QEfpPsct427s/tsLdJdYECD2?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8e6f9877-f5eb-49d7-c6ee-08ddcb9780db X-MS-Exchange-CrossTenant-AuthSource: SJ2PR12MB8943.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Jul 2025 16:22:52.0645 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: hl0AP6zI1yyL6+56I1FfyFctwGeaOHJV/c4ixDJD+3dXhPSHMCvS7/ctECA3MAI70dJrJE9TGWU/FUyNdHexzw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB7322 Jens Axboe writes: > This seems like entirely the wrong place to apply this logic... I understand it might look strange on first sight to have the check implemented in this low level iterator copy function. But it is actually where it makes the most sense. Let's assume we move it to the caller, nvme-tcp. We now need read our packets from the socket but somehow when we reach the offloaded payload, skip ahead. There is no function for that in the socket API. We can walk the SKB fragments but a single SKB can contain a combination of offloaded and non-offloaded chunks. You now need to re-implement skb_copy_datagram() to know what to copy to and where at the socket layer. Even if you reuse the callback API you have to take care of the destination bvec iterator. You end up duplicating that iterator map/step/advance logic. Our design is transparent to applications. The application does not need to handle the skipping logic, and the skipping is done in a generic way in the underlying copy function. It also will work for other protocol with no extra code. All the work will happen in the driver, which needs to construct SKBs using the application buffers. Making drivers communicate information to the upper layer is already a common practice. The SKBs are already assembled by drivers today according to how the data is received from the network. We have covered some of the design decisions in previous discussion, more recently on v25. I suggest you can take a look [1]. Regarding performances, we were not able to see any measurable differences between fio runs with the CONFIG disabled and enabled. Thanks 1: https://lore.kernel.org/netdev/20240529160053.111531-1-aaptel@nvidia.com/