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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?yv5dEB7kdesbNkjm6/ybfssKJfrkgjAiXYSmLJrr6I/7e+FSgMHzDJyFhOS/?= =?us-ascii?Q?WxgYnCLPy6iJi3wu256ytMcBXS4VjpQgyjiLY8vkiQKy5YXDdzdkZ0tQ1uSM?= =?us-ascii?Q?9RvehSyeIRmKwPE7KmbUH4Kmxh7cyQ9NMAw4LsWVVQkeqPoo9yEuE0Qz/y1+?= =?us-ascii?Q?rvLUZ4HwLhhbOSuvutBzjnqCID/gJ5sjNWx7X+XLxxmyFoxzPNtJAGS+eYIp?= =?us-ascii?Q?fdjcFjDg0VktiJr0k3yQLHxndzOdkaw6mIR8UnPYu2Iza0kCXOzfNqPgrQmz?= =?us-ascii?Q?OkVU/+kVkPnj86QH0gykvFESSN0ktGJ133CBpu7dJMyvjfkW9gXAfSeBR3IG?= =?us-ascii?Q?BGRL3EFC/4IYD6X7DaTRO+NKliuzSgZ+ENy1j3KYd/+3ZvcWFGp/T/qeDkAY?= =?us-ascii?Q?vCqXgp1efuVi/bMV/RLh1gq9WqnnsgfDAM+pXV+gnG4ufX6DKyEE9FeswRwN?= =?us-ascii?Q?Yb1MCJGqmkBybncMYM2jYEE/8fpKSakpikiWWBwgOEiI9SZ6GtCFOuI5ELfW?= =?us-ascii?Q?XMnnOCMSwBvJLoZYYNjYETFTLHHtD1sz7ud6XXgxdrX5X28Mp722M9B8mMOZ?= =?us-ascii?Q?zQ+UdYOdSUj3MgW8bC2R1/7uRr4ZMw0dIF8wHSA65TxjHSSDcIoCKJX4tyeq?= =?us-ascii?Q?l/voA1h/zo9Dk9czQrVkHb3nylNwNPOg+eg+oVgvMmt/DYiomaLwpRA0cJtY?= =?us-ascii?Q?lAU0axLnBYu14+eVLDMrtSaggsb5s8PzrXcUuBIBYkb8rQGzA/7ZAmymcgXa?= =?us-ascii?Q?PplHJiovFr50BqDJl57z3i3DKOxW2tgbUBYmXtXBhOMU7Dfi8Gp5/TGCsi/J?= =?us-ascii?Q?S0h3O3C6LVn/h2beoMyoeWFHzN2nKkoRqWHtGv289UhiczZHeS1xg3Q437Em?= =?us-ascii?Q?J4N+L/gNR/yIRXX5tp1VslCOg4O2kz8ZZ5yNER/bifvK/C0LcmCBKZyUguuK?= =?us-ascii?Q?qvzdxme0rixDF5zpQ+b1MCTMTb+pWRLbJZITRJBWiDakBXZpBb31ZfOawrro?= =?us-ascii?Q?VwVPSZT4xCv6eOLFXcE6q03dEc3jUN+Rn1kaMiT+43ZoxPY3L3xdtezebQv+?= =?us-ascii?Q?G5ueZHtIMDX2HarK8ETOphjnJGycFLaJZCLm8SdZmMhw93ncdnWZGDidTZYg?= =?us-ascii?Q?Xbt2iLLcxdnCsor9Zm1y2F7MxBMaO9SaPXKBJ+MUF4fTKobco8iReUK300ur?= =?us-ascii?Q?HE1ejwDCze/geF3YxYO/9oR1/rpQ8J+PQ79NcXg97o6m6sYv6x3yXwc13+6S?= =?us-ascii?Q?GlKgfPzjzKjReT8GPZbj6ieh5y0Dk+GNgmnfhPZ3QOBPjWmsodxj4vY5uGSE?= =?us-ascii?Q?c8MiStRACw2syUoGTZST853/L3gQKY15XhrppM+FqU6Pa710Ew5fq0+oegXG?= =?us-ascii?Q?s4G2U2L5syg0l1dTULh4+z2G197lbA+t0HH2Ze3TeLiaAa38RiepXaOKRKwg?= =?us-ascii?Q?DquwBlMH63N43ubd0DadVylY0VKRhffUjFX8pkhg3PiFoe22TCglTIRTZD/D?= =?us-ascii?Q?RgMPG2j21kQKXBPPdiY72t5T4yDzzcLVS4U4IGvyewbedodN1700xFHMfZ4s?= =?us-ascii?Q?nWj0s8MKzyT1qjyuMhnLh3UZsA4l3KBQ6g6AwWYivAznwNQ2e2Cry3acBSEJ?= =?us-ascii?Q?c5vm4t34068buFynBQcSHsDfYp7LF8iN7VA8wxTJJRpZgTwrEeP6nPxtp6xu?= =?us-ascii?Q?ywrn0Acl80wgX/yd5xDN3s9lgjYjMRUAWvlq+bcGEsKr/5vF?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: d4d9612a-2e0b-410d-a961-08df2dbdd7c5 X-MS-Exchange-CrossTenant-AuthSource: BL1PR12MB5174.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Oct 2026 08:49:10.2948 (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: 8lPPmOzWpERL90/UBN2WHLs98RUPLmA2ncW+qhJLk87B/tc+SOQuiqWOazBvl/d8CkOmydY0fDncaSLloADnrQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA3PR12MB7807 On Sun, Oct 18, 2026 at 12:52:46AM +0000, Alexei Starovoitov wrote: > On Fri, Oct 16, 2026 at 12:52 PM Andrii Nakryiko wrote: > > kernel to do that. But once we have the ability to create ARRAY from a > > bunch of pre-existing memory (e.g., from memfd), this can be used both > > in a guest and in the host, and both models, guest allocates or host > > allocates, could be supported with the same model. > > I don't think it will work for their use case. > With array of maps scx needs two lookups and two NULL checks > on every access, and the result cannot be kept in the task ctx > which is in arena today, since ptr_to_map_value becomes scalar. > unless everything is converted to magically bounded array, but... Agreed, from a sched_ext perspective, arena is really what we need. Most of the new schedulers already keep their per-task and per-CPU state in the arena, and an idea could be to link that state directly to the shared hints, e.g., keep a pointer to the vCPU's hint slot in the per-CPU context and dereference it in the hot paths, without any lookup. Andrii, about the 4G / single arena limitation: for this use case I don't think it's not a concern, the shared part is a few pages per vCPU. Having the shared pages in the same arena as the rest of the scheduler state is exactly the property we want. Thanks, -Andrea