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McKenney" , Metin Kaya , Xuewen Yan , Thomas Gleixner , "Daniel Lezcano" , Suleiman Souhlal , kuyo chang , hupu , References: <20251030001857.681432-1-jstultz@google.com> <20251030001857.681432-7-jstultz@google.com> <0c337bca-4ecf-4654-9256-df766573c7de@amd.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Received-SPF: None (SATLEXMB05.amd.com: kprateek.nayak@amd.com does not designate permitted sender hosts) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PEPF0000000F:EE_|MW3PR12MB4363:EE_ X-MS-Office365-Filtering-Correlation-Id: f879d8d5-ff50-4640-2133-08de27e0425c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|30052699003|1800799024|82310400026|376014|7416014|36860700013; X-Microsoft-Antispam-Message-Info: =?utf-8?B?dHJZaWhsNE9kTG9IU2JGelZxM0c0RnNodFU0QTBOQU9tbnlaM003OVgrOWx3?= =?utf-8?B?Z2hldHdPekNxaTgveEdVZTNiUUh4YjZaVHY5LzEyQjVxc1QyRVRVVEJQV1Fz?= =?utf-8?B?ZWZvSVNGRHZyT0VoZ2pMQlVKd1pWWW1JNFRFck5UdGNTQ0x2Z0U5b2xmbGF6?= =?utf-8?B?aUFSWFRkV1dEenR6elFqWElwZjI4MUVGa3BZaXNGUHJkUTBnemF6TjRFTjZF?= =?utf-8?B?R2lZOC8wZjc3VzhMWVZGWjJOck5OMDJDUEpSYzk0Nm1RL0NPTXhXL0krbHA1?= =?utf-8?B?K1BPQXhzd2FyNDJpTTdjUThiZXVSTi9JdlY4Y3VUV25rMS9YSXhmTWJHMzhj?= =?utf-8?B?QlI3OEJSekk4WWh0QUpXOEZMQmdRNVNLYmlRZk01U2JuQ2hSbzFXN3B5VmJq?= =?utf-8?B?SEtkQ203NzdQbEFPYlVHZURES2pFRllYN1Y3aHA1d3RCMEY2TjVSSHpxZ1pr?= =?utf-8?B?ZlROQ3NxWDN6Qlh3THRSb0plMDNXUkUyZmppZHQ2U0EvckpHQVFRMjM3czU5?= =?utf-8?B?S0doRWJVdUtxaC9vTjN4ZVhOSUEyWGpibityMXpTUEVLa2p0Z1dHNFBEUURX?= =?utf-8?B?dXpRSFBRUUpMdy9jR0ViUWRPK2RDd09EU1IxUzlpdkZjWHpGSHhrRjFFYzJl?= =?utf-8?B?bnROM0V6dVRjU3JZSmtLY2hZY1ZncVQvNzNkamhDNmRsaGJ3b1lhOUFpbEty?= =?utf-8?B?YjVidGM0K0R2L1hGRy9RcmN2ZnVvenp1YjZ4RzFjR2haSVN1blZQd3J3K1pX?= =?utf-8?B?b05yWXNQVTBZN0ZYQURteXYybzZjMmJHM1dsbzRHKzk1eFlmL0Y2cGZnWEta?= =?utf-8?B?bmVPSmJHVVlsMHFPcU5HcFVJdStxenlYQ1U4S1h3MUhFTkEwblBtU1RDbWM5?= =?utf-8?B?WGc2UFR4VW9PUGZMbERRelpIVmIzeVA4SUJQNlhMeE13UkRaQ3FoMHp2TEli?= =?utf-8?B?VXlQMkxZZE8rTExkZWtPRU9XaUxCR0VtWThuQkxqQ0lhZFpSQ3E4VDNWOXZY?= =?utf-8?B?amFhaS81VlU3VnBQY0hGVkw3NUxVTDFPbnVJSS9TZUxUVVJwNS9rMXh2enlX?= =?utf-8?B?am9QYXF0bmNQdVpYWFRldm9sTjh5U29ENHU1SlZGSE02REFjRlBFTmljSUt1?= =?utf-8?B?R093aVJwUlh2RC9WN2d5SUc4Mk5WZHBOZ1cvRXU4ZHc4MXlVUWJEN080c3pk?= =?utf-8?B?OVlPZDN5OUlLOFpXdjlOQWdXeUdNZTRBQU5zaHdKTWRYUnhHSDB1eVgwSlFw?= =?utf-8?B?UnQ4K3FQSzU2OUxaa0ZmbDhDTmtFU0lYenIrZEtTcTlHblRRWFRWeHpxTFdo?= =?utf-8?B?OUxmejMvT3hmZjFpZzBKTjlsaDFlK2IvcXo4cU90MjllRHlOYmdrYTRLK2tD?= =?utf-8?B?bHlEcW1zaUFRUUx0VGx5SmxwOUQyV3p5MTZPQ2RWUnJLNUN5ai9KcUhkeHR6?= =?utf-8?B?eVlQUG55RWNYY0s2RUFKRXljNkNnYWwrZmR0TUdNcjVwTnBBTU5IVEVkV2U3?= =?utf-8?B?T1NUMkViZ0RnTytIQlprSkgveFdpdkJySmJmM3BnblFCMmVpTS9TQXdaOUdJ?= =?utf-8?B?anQ0aENib0NRbUNDcXhLYVdrc3ZhRDdlSkhWRVVvVUtCZ1BLTVcrWEc0bC9w?= =?utf-8?B?djVLUGNkUllBRUxvWHl5NjkzNmoyUHNaQ3JoanZCbjhEeHBNOWVlME1vZnBh?= =?utf-8?B?c0c0TkFBV1BtQWxCN0dHTWN2Tys5Z0dONHgvSlRCdlpmdlVXSzlmQ2ROQm1w?= =?utf-8?B?TFhtcjZrOC8yRlIySkc1OExnbjVZeFJiVEpUSjk2RWJWZ3NrU1ZxS0pMV3ZV?= =?utf-8?B?K3ZTZ1hUeTBKT2xOc0hFYjAwTXJubUVYMklKSk5ReUhxS0ticG5tQXg3UzN3?= =?utf-8?B?NkxsanZPSUJid0xUK3BOL0lFLy9RdXlWbmJPVEsrV2FrV0VvcHNVaGdLdTIy?= =?utf-8?B?ZGRlZWFHSTNPRUZJZlE1TGhhUHpaRVgzQTZvMFY3cno3YUFXcGhDc1kwYTdS?= =?utf-8?B?Z0pMK3hnR0ljaGovR0xUbkh4ckhFK1hlRUlEaFVNR2dYZW5idzFGNGN5Q1M3?= =?utf-8?B?Y0s4b3laa1dpT29LS0NEeUFzTC8wanB5L3FZcXVSYjNiaG9mRXNPQURGSEVZ?= =?utf-8?Q?FH8A=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb08.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(30052699003)(1800799024)(82310400026)(376014)(7416014)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Nov 2025 02:55:27.2347 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: f879d8d5-ff50-4640-2133-08de27e0425c X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CH3PEPF0000000F.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW3PR12MB4363 Hello John, On 11/20/2025 7:30 AM, John Stultz wrote: >> Ok, so you're suggesting maybe putting the >> if (task_on_rq_migrating(owner)) >> case ahead of the >> if (owner_cpu != this_cpu) >> check? >> >> Let me give that a whirl and see how it does. > > That said, thinking another second on it, I also realize once we > decide to proxy_migrate, there is always the chance the owner gets > migrated somewhere else. So we can check task_on_rq_migrating() but > then right after we check that it might be migrated, and we can't > really prevent this. And in that case, doing the proxy-migration to > the wrong place will be ok, as that cpu will then bounce the tasks to > the owner's new cpu. > > Hopefully this would be rare though. :) Ack! I was just thinking of some extreme scenarios. We can probably think about it if and when we run into a problem with it :) That said, once we decide to move the first donors to owner's CPU should we task some care to retain the owner on the same CPU as much as possible - take it out of the purview of load balancing and only move it if the owner is no long runnable on that CPU as a result of affinity changes? -- Thanks and Regards, Prateek