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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Nov 2025 06:50:40.8063 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 3f4d77d4-c64a-4575-7719-08de21b7cb6e 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: CY4PEPF0000EDD7.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW5PR12MB5684 Hello Wanpeng, On 11/10/2025 9:02 AM, Wanpeng Li wrote: > +/* > + * Find the lowest common ancestor (LCA) in the cgroup hierarchy for EEVDF. > + * We walk up both entity hierarchies under rq->lock protection. > + * Task migration requires task_rq_lock, ensuring parent chains remain stable. > + * We locate the first common cfs_rq where both entities coexist, representing > + * the appropriate level for vruntime adjustments and EEVDF field updates > + * (deadline, vlag) to maintain scheduler consistency. > + */ > +static bool __maybe_unused yield_deboost_find_lca(struct sched_entity *se_y, struct sched_entity *se_t, > + struct sched_entity **se_y_lca_out, > + struct sched_entity **se_t_lca_out, > + struct cfs_rq **cfs_rq_common_out) > +{ > + struct sched_entity *se_y_lca, *se_t_lca; > + struct cfs_rq *cfs_rq_common; > + > +#ifdef CONFIG_FAIR_GROUP_SCHED > + se_t_lca = se_t; > + se_y_lca = se_y; > + > + while (se_t_lca && se_y_lca && se_t_lca->depth != se_y_lca->depth) { > + if (se_t_lca->depth > se_y_lca->depth) > + se_t_lca = se_t_lca->parent; > + else > + se_y_lca = se_y_lca->parent; > + } > + > + while (se_t_lca && se_y_lca) { > + if (cfs_rq_of(se_t_lca) == cfs_rq_of(se_y_lca)) { > + cfs_rq_common = cfs_rq_of(se_t_lca); > + goto found_lca; > + } > + se_t_lca = se_t_lca->parent; > + se_y_lca = se_y_lca->parent; > + } > + return false; > +#else > + if (cfs_rq_of(se_y) != cfs_rq_of(se_t)) > + return false; > + cfs_rq_common = cfs_rq_of(se_y); > + se_y_lca = se_y; > + se_t_lca = se_t; > +#endif > + > +found_lca: > + if (!se_y_lca || !se_t_lca) > + return false; Can that even happen? They should meet at the root cfs_rq. Also all of this seems to be just find_matching_se() from fair.c. Can't we just reuse that? > + > + if (cfs_rq_common->nr_queued <= 1) > + return false; > + > + if (!se_y_lca->slice) > + return false; Is that even possible? > + > + *se_y_lca_out = se_y_lca; > + *se_t_lca_out = se_t_lca; > + *cfs_rq_common_out = cfs_rq_common; Again, find_matching_se() does pretty much similar thing and you can just use cfs_rq_of(se) to get the common cfs_rq. > + return true; > +} > + > /* > * sched_yield() is very simple > */ -- Thanks and Regards, Prateek