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A boosted departed task counts as a deadline task. A rebuild meanwhile counts it once, where it runs, and records that CPU. The deboost then releases it from there. A deboost that races the rebuild drops the bandwidth until its 0-lag time. dl_bw_gen then keeps the release from removing anything. The move in (ii) is admitted in the destination by cpuset_can_attach(), as for any deadline task. In (iii) the walk counts each deadline task from zero, and the release removes it once. v5 documents the deboost race in the comments. > stale dl_bw_cpu when dl_bw is zero misroutes bandwidth Right. No move updates the record of a bandwidth of 0. v5 makes sched_dl_overflow() use the task's CPU for it, and adds a selftest case. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com