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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?4DpSxSp64Q4MeqaI3GrCMjgONKVzN5rYAAdBJ7zEVRmZd02WA8X7KFKaK7n8?= =?us-ascii?Q?XbD6h+QXp09bA3xBS93pfnIQheSYYIUwqFRd3X+wPRlt00LqTP3EF3y5sRmv?= =?us-ascii?Q?v3PuEBU5BmC+QekGBPfFvkEm4JnlTUF1cYg19eKLt+cg8SFa6boAuxyp9Tfq?= =?us-ascii?Q?TE97ASOQ37WKtm+UplCVTyyzKGVVDEvu4IU/vv209mWb521W7XuMgb4igb1C?= =?us-ascii?Q?UY+ApO+q5N5Fd2E9zr0ezKZXq7u74n9Sp610ikGzi96xdMcyijKVNnFtgG84?= =?us-ascii?Q?CCrilx2dyn7wleWWm2aII16i4uu22YqEzMKSCS9H0Mi6tcSPinXtwv5u8s98?= =?us-ascii?Q?hLQW4muFmd2RvSIM1vNwRHNj1Muv8IHIXs7UNgNZ5fK76LiuQcFuAp8uAGft?= =?us-ascii?Q?+PBvAyhJ4k3dgGAz7ZaoyJqGIZvIHcPEnMUjUXRfYy0s++ojs1Bh/P5bqXMz?= =?us-ascii?Q?+xW7FzpPcnSSbz3HBpFqr/RvqpB7zocUc0oY/U+0Q24zjq3Y3nmHHz0aNtBx?= =?us-ascii?Q?7zYHiD/jXrV8Yjtyb709JozjZdijjQ2ieFXBnMjIS0iq//gWameWrtcOuwld?= =?us-ascii?Q?6+9+Rk9JHs/GZtro6OVPCXTK19vEAq03qMZuA54pTFYOYmrPnxHY6FrXjE5z?= =?us-ascii?Q?djEzxA9cUPxe4Y4FF3wn3IJbfwE1tuPvYZM8XzaXUhyUT8zaeObydm0Xbd1g?= =?us-ascii?Q?LGJW67VtlweLcuUEQg6YcsRGgKazEyCIZA83EP3OgKynMO9cLYBvkrjt8q+2?= =?us-ascii?Q?j1Nl3MyFNNPhLiHpsQ+9NpvDDbhW+ohGoa//LjmGDl6kXVUPzGqrndrhvK6k?= =?us-ascii?Q?riNErzJzJ5o/ccRIhgzFJulRMyBvu70EnHDAGN3V5Q40FYX6OJtsae1rJh5s?= =?us-ascii?Q?aqAUNE2nUZVwx3bVzL4OGoJsYvtNa8dp4LAYLqjV8v011xWMjoMDT/TZ/VaA?= =?us-ascii?Q?ayu/S+zeB7z7iZuqCgOur/Ak5QytnsE3vG+Ak2tnn6yCBGnZvcT/LKmZd9o0?= =?us-ascii?Q?soFuNj6BSejKS8kkZm6vLfecUefbZ7iz8ctwGFRYjhVDJRQHPiUJ3/yYAaGd?= =?us-ascii?Q?SRFNg2NS1f/Sba7ZR/i5XJrKESa/vVUs76eKajqSzTixuEL/0USdrMtBIZFC?= =?us-ascii?Q?by4vpPAli3Eri+Mtv5ebjdW4bNwW0iVnN/BrdAglPSWiStBC7ThraHnMLam2?= =?us-ascii?Q?OHtZyRvCjH1lPtvJsreHpQ170sFuDeXGZ6/gwRx8hn+XsdnJlSJHm1IRVtuM?= =?us-ascii?Q?xU2WvK0UYTyZco5cXmuzu+raiLhKijdjsHvoMstSiv1CqjigYF2r817UZAEf?= =?us-ascii?Q?Hosl6JnbDV6b1uIXeV5QHAqS3Rb//ShW1V0+LuzpOLO4jJj7gE8chYHX8t4r?= =?us-ascii?Q?whk+DqWHiJBMeKd93TURPPJzzB8dmFqSy0jjXVeveNJfG05GqheBTmp7cNsE?= =?us-ascii?Q?uLhCldkRP2FYCUyYEA1zbsW5LZeDfqIvs5AXTqcopPDYK/wB3ytoGdGBRRHu?= =?us-ascii?Q?MkX4Ya1PwR1Y6tBBd5wzkn6VTma3dyy/olTmocOSbKvt9DBgGsGn9m/0laXR?= =?us-ascii?Q?UDUmJj94a6b12/VKp1muae7ofuRAj8agHIBlfFOuvHEFYonRtO2c7nt3+sEY?= =?us-ascii?Q?Ug=3D=3D?= X-OriginatorOrg: santannapisa.it X-MS-Exchange-CrossTenant-Network-Message-Id: 52d71cca-2a75-49e7-d779-08ddb0050169 X-MS-Exchange-CrossTenant-AuthSource: PAVPR03MB8969.eurprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Jun 2025 14:16:10.3352 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: d97360e3-138d-4b5f-956f-a646c364a01e X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: zg5LB9snMePVpYb6rdoXgh5aMTLC0qrmfN1u/Uv8gr0iD5eMGQpxGxqm3Q0ciojVgutSfe1Dlmwjna0hBCKpSb+LvBpcV7ZZW1Ey4hi9oQo= X-MS-Exchange-Transport-CrossTenantHeadersStamped: DU0PR03MB9707 On Fri, 20 Jun 2025 11:37:45 +0200 luca abeni wrote: [...] > > Luca, Vineeth (for the recent introduction of max_bw), maybe we > > could take a step back and re-check (and maybe and document better > > :) what each variable is meant to do and how it gets updated? > > I am not sure about the funny values initially assigned to these > variables, but I can surely provide some documentation about what > these variables represent... I am going to look at this and I'll send > some comments or patches. So, I had a look tying to to remember the situation... This is my current understanding: - the max_bw field should be just the maximum amount of CPU bandwidth we want to use with reclaiming... It is rt_runtime_us / rt_period_us; I guess it is cached in this field just to avoid computing it every time. So, max_bw should be updated only when /proc/sys/kernel/sched_rt_{runtime,period}_us are written - the extra_bw field represents an additional amount of CPU bandwidth we can reclaim on each core (the original m-GRUB algorithm just reclaimed Uinact, the utilization of inactive tasks). It is initialized to Umax when no SCHED_DEADLINE tasks exist and should be decreased by Ui when a task with utilization Ui becomes SCHED_DEADLINE (and increased by Ui when the SCHED_DEADLINE task terminates or changes scheduling policy). Since this value is per_core, Ui is divided by the number of cores in the root domain... From what you write, I guess extra_bw is not correctly initialized/updated when a new root domain is created? All this information is probably not properly documented... Should I improve the description in Documentation/scheduler/sched-deadline.rst or do you prefer some comments in kernel/sched/deadline.c? (or .h?) Luca > > > Luca