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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?nAauHLHrHispaAub8b7dJ0w0bYDICMO+wxgrix3UmsLKQ4dV1l+q7O8DgqZd?= =?us-ascii?Q?8I6tCzq+QecPGjtgOWQvYchiTH+/sik2QyOn5KMplu7yA1YcI058zxhtJzIf?= =?us-ascii?Q?JLXI/gEOsYNmOzBGpmsbtSVhc5/0wSwuPn3kOESvpPH2uk6Q2dN1lprYRoUE?= =?us-ascii?Q?kFVed59CnAsE1zrKDG1TTEb+fliQxXagP70/8siAj98om19jTOnyFF9hTRsK?= =?us-ascii?Q?K0fz8AhJJIjFbCCbdnx9TnKFnFtJSL4GZJK/Dw39Q8o4CYSGqBarK8+pl2WY?= =?us-ascii?Q?6DB6is5zZzYqzzu68GSTmsbGYWvO1iMCiTVm2tFynxpyJaKbNHlDfd7VJ/+f?= =?us-ascii?Q?TpiCC48HF8XTWJjjj9LnhZ+ikHXCczij9azmO94cZgYb/OL4PexEDPO9HFhR?= =?us-ascii?Q?fV/H4L/cmCJU4xwYdADVzqt5z0NELVO+AN81FLnEGWfl5mkp2VVJ7J2kysci?= =?us-ascii?Q?HPM0bqwiKgiEtHSAtRauikayqNX4h6B/ahBOuLX2Z6pJPrdQEYb7AD6nWpJ2?= =?us-ascii?Q?l9XXiPtCZDb9o+1SD0fY2t30dNmzNdn+o7l/HxixKmJxYgZsm5YGUljFLcwa?= =?us-ascii?Q?PsjoLOo0opKax0DNMu1bGFdBqJX37XQ+bJ3Syp+zP2RgWhF2AEirspRajS7y?= =?us-ascii?Q?2VO0+iYBhrcNjb+1lIglwcFWfsIcBjOyb6oB7WQuyzyfabqtBaFGhoz1AvMf?= =?us-ascii?Q?4XdcV2yVzBFAA+7Q7lINks9ffmkNg0bwELxUTEWdYZzjXRNFkJQmwUx9/8jk?= =?us-ascii?Q?u3aS0F0SGQxwjtpV5pOifWUGi+/myTLbF+ZG7QhBlVGg6r+EF58ES1NsuiAv?= =?us-ascii?Q?OzhjnTMJZ0t5q8QAjuXEVcq7TzRO2q4wSq6Tcqqo7tBQawDxtnNbs6mP0gsr?= =?us-ascii?Q?kmGYTdlhCH13tp68QvywiAL7pFZ4+8mIJYC6Tb46Wt0q+BlZkorQ1d1UABH1?= =?us-ascii?Q?22nYy6jaye4pNK7JLpL2eTcjZqQcz6lI8IaVHkbb7hGfkaWXpLPA05OmaL/r?= =?us-ascii?Q?CIXMwdCldGFosE1MLygaYVIAlXzw1g97Sg9RnUwDD+YLAOSG6ySwLhCDze67?= =?us-ascii?Q?QoNAQErCn0qJZmrm1cYs1nY9S+nDm6KC8fjMuwsgzaUbfg5whJt6i6bRm14V?= =?us-ascii?Q?qax8OX/GGaenP1S5Idut7znTzMQ4FyFbDmSAWqAeIY+2aC5vcwLBw57w17fq?= =?us-ascii?Q?AxLagImk4WdmgFe3EJYi+e5bTRCsRBkEQsgD9KGPZ+3tC9VSa8cIMDk8OkAU?= =?us-ascii?Q?GZAJGq453qI8yMP1yVm3WcAEG2wB+pW6EQj5trsJoQVUfFh4cx4DdQJ9+4cu?= =?us-ascii?Q?xnqKolw68djmOcfSeihyz4mvEFwQhkj/KJT2DrHRE0swPQfvTEwCu5cwEHKE?= =?us-ascii?Q?gII+OS9dX0vZxwv+SKp3q/VDk67Ehz4r8cOdMZ527+PRyfb6hbkn+QgCC23Z?= =?us-ascii?Q?rU54+3GTe3ADYymZHJlN224a2m4idqBzhqxMLOlwn3egExKPQ6EkK8vpUh2M?= =?us-ascii?Q?vuvs0E+l+OYiySK4KoJmlN2NQMdj0oNx/70SBAmAbEngpdnjAN1yCNq4rKf3?= =?us-ascii?Q?lGcKhnkLbjspI9FnR1bFni0Lg0zWi5wZiDMEo+TWtEvEsqdOHGJ+jvgAWzrI?= =?us-ascii?Q?o/PDVfPvAMXOWCHel6Ali86ew7fmKfWN3+0kAiubpwIp8Ucc48UyDTuUmxlw?= =?us-ascii?Q?8uvFvlsa8dyfuwEY6yerRK69q/RtwbOia3saYzIcYs5EGQ32?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 953e1a4d-1990-4406-b849-08de67dbfd4d X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Feb 2026 13:06:08.0468 (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: C8lnronyt73bOjYqlawQiBmWGkbj+uN7LpQ7RV4rZwX7XAum0l6Q31sGyPvm0VKz X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB8457 On Mon, Feb 09, 2026 at 10:59:53AM +0000, Pavel Begunkov wrote: > > As a step forward I could imagine having a DMABUF handing out P2P > > pages and allowing io uring to "register" it complete with move > > Forcing dma-buf to have pages is a big step back, IMHO Naw, some drivers already have them anyhow, and we are already looking at optional ways to allow a very limited select group of importers to access the underlying physical. It is not a big leap from there to say io_uring pre-registration is a special importer that only interworks with drivers providing P2P pages. It could immediately address everything except pre-registration. And do you really care about pre-registration? Why? Running performance workloads with the iommu doing a DMA mapping is pretty unusual. > > Pre-iommu-mapping the pool seems like an orthogonal project as it > > applies to everything coming from pre-registered io uring buffers, > > even normal cpu memory. You could have a next step of pre-mapping the > > P2P pages and CPU pages equally. > > It was already tried for normal user memory (not by me), but > the verdict was that it should be dma-buf based. I'm not sure how DMA-buf helps anything here. It is the io uring layer that should be interacting with DMA-buf, the lower level stuff shouldn't touch it. Jason