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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?UytFeQr38tT8oyrQ1049oJUSt7JyQkOzZazkn5SxkEovDM7LZnUg5Y4IQ67f?= =?us-ascii?Q?5HGyLBkH+1hY7JAvrHMo2y16Pt4tWHCV9PN8R47lMkoz7oy8z8JSNV9C7aF+?= =?us-ascii?Q?+xdwVn387ktKX4Yv7EJ44RejUavyVGLaznFKgQy3ZxN1pFK99QNHd0TYQb0n?= =?us-ascii?Q?2gmVAq0EAnTr9tb4CyWN9yZpYzLA6Vot5p5ay5z5M5baVLdWRj8y7vhtzJ5c?= =?us-ascii?Q?349kka7xguvjZ4kTqYGHDmy0J4dfmgMhNs21hsttO5KnbdpF/6fCPx/2GVvh?= =?us-ascii?Q?5Z80/ledHAV6UraKdiWsk4zVbmmL++jVTsVLhl/wQiVV5KLHh2nM5sBYxI2h?= =?us-ascii?Q?tPCc89+u/mhe+k914NMYYpFb8mvVTpbWsmr06UNClmPV77H19PsQox4OgG8j?= =?us-ascii?Q?ACCJTXICCvIEeW/EOEY0OVGAm1XkRrPPoWLrYKm7Gtf/0pzG1zSV4yQUefrJ?= =?us-ascii?Q?2qEg18FrADVbrhWuFUHgtUOhxBPC7CNiEhfCByuw7rwdEqlaSHqCKJG3CoBi?= =?us-ascii?Q?Udqe/8zPJr3euPeVw2luwDPsNBGq368Dtbv01p6UxbXVkpoSfyuaNakorwxg?= =?us-ascii?Q?1hjmQXJE3HPGdykWQ2uzA2BOzR1VLCQCqdB4d+eTQNOXjvGHgJ+OkboyTSUT?= =?us-ascii?Q?yMPxFylm+KcTRwBHptVwKaO3dMVx92fb+LQsIwuP2e8boGyR50i2cP189Bjn?= =?us-ascii?Q?t5hn52PoP1/55k3JNZuWQ/6Su9oYuhzkQNs/agXcHwU7LjdaYWo5R2HgkLoa?= =?us-ascii?Q?xSVcQHnMx7ZH0XSb0dcWNm4do4/JAPtHsgtvkh5FE6lPjRN2AIGxXiAPQYdU?= =?us-ascii?Q?PEAKUYhMwMff3JPCsKGi7wvuRE1OpE6Ail/9n1Jppv3XRNaPoQkpj5NKPHfp?= =?us-ascii?Q?3OAasDhfevRoQzGBm0VgNkq3lUNjymq2c/xN1ucngK2gSUzfBOp/2sMDaYFW?= =?us-ascii?Q?MhcIf/su0yC8JJjuUtAfR2KivVweGY+d3MOz9niEYPPZSrw7Hn09f8YhtB6A?= =?us-ascii?Q?aQdxSMy7arQal/mYmhk+4ftN1gvBXWPhIXtA/o9YljNsyg5bL7tgbHb/Ijgr?= =?us-ascii?Q?slcY4/pKs4iVtd0sAJEbFeFYX2wilimok0YrnfDmtF7ghzsJ4IN5InykEg3I?= =?us-ascii?Q?as4BT+w9rbtfGYTvROAGCEzeD34bTNNuTB39t0iQepjlRmutSuDx6Uea0QMA?= =?us-ascii?Q?xTMKnqVjN6XkRAWy3crKK1cPmbyJ6DrsPeZNMbFQlyiktu72OgnEolbUTWOh?= =?us-ascii?Q?oT2+9g04CBEOLiK75TwrVw8u8xclEg630i0nq0yZQJxUmcl7PkI5c1/NzZgE?= =?us-ascii?Q?hZp3uYLZ/BmQelG5hRwiN/Rg/qSqSt9CkMJhYcnFKJw0JDgewOA5175ETp/C?= =?us-ascii?Q?mXbiXly6vLuQt39b83Do5SQa/ZJcT1B3xi/ahZJe/eXv7IeDhXL8K6Hc+Ol/?= =?us-ascii?Q?6dKAk9XTIXvvB/pzv+aEHaAJVcER6anvO7u+AvQRsuL0mF8Kffd1tdLHB3vx?= =?us-ascii?Q?8UfJmEVeGsyvP+HfI3WSWgsxqDTjWeVNBlM0eQrUGZ8J7pIQYqDv7UfWBFb4?= =?us-ascii?Q?4nGJXztqArJCW6A7i/kMjwXwHKcvHmoMrGD1sPvD?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5333ee8f-e97a-4489-deb6-08dda8ab79b9 X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Jun 2025 05:47:39.2895 (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: /ule++B1mxk7o9qMx264VjFRl6KBBM5yNkkDwgHYB5+bQTajVyJp8bhKXw/H1Xf/HIBijpHm8MUGjkBgcxsJEw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB5866 On Wed, Jun 11, 2025 at 02:22:11AM +0000, liuwenfang wrote: > Thanks for your feedback. > > Another one issue is that if a runnable local SCX task has p->nr_cpus_allowed equal to 1, > and there are RT tasks on this CPU's runqueue, we need a chance to let BPF scheduler to adjust RT > throttle param properly(or other methods), so that the local boud SCX task will be scheduled > in time. This is important for the mobile scenario to render smoothly at 120 frames per second. > scx_bpf_reenqueue_local will not work for the local SCX when p->nr_cpus_allowed == 1. > > Also some tradeoff methods can be taken to balance the performance: > If the running SCX task is preempted by one short-running RT task(predicted by its history), > then it is better for the BPF scheduler to keep this SCX task on its local dsq, rather than directly calling > scx_bpf_reenqueue_local(). However, we still need protection for this situation in case the > short RT task become long-running task(perhaps due to some exception). > > Any suggestions and comments are welcome! This will be all addressed by the DL server work that Joel is doing: https://lore.kernel.org/all/20250602180110.816225-10-joelagnelf@nvidia.com/ Thanks, -Andrea > > Best regards > > > > > Hello, > > > > On Tue, Jun 10, 2025 at 08:59:45AM +0000, liuwenfang wrote: > > > Assume one CPU is running one RT task and one runnable scx task on its > > > local dsq, the scx task cannot be scheduled until RT task enters > > > sleep, if RT task will run for 100ms, the scx task should be migrated > > > to other dsqs, then it can have a chance to be scheduled by other CPUs. > > > > > > So cpu_tick is added to notitfy BPF scheduler to check long runnable > > > scx on its local dsq, related policy can be taken to improve the > > > performance. > > > > (cc'ing Kumar as we discussed similar issue recently) > > > > There are some race conditions we need to address but calling > > scx_bpf_reenqueue_local() from ops.cpu_release() is the intended way of > > handling these situations. I don't think periodically polling from ticks is a good > > approach, especially given that ticks can be skipped w/ nohz_full. > > > > Thanks. > > > > -- > > tejun