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    SubjectRe: [PATCH 2/4] sched/deadline: Improve admission control for asymmetric CPU capacities
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    On 08/04/20 10:50, Dietmar Eggemann wrote:
    > +++ b/kernel/sched/sched.h
    > @@ -304,11 +304,14 @@ void __dl_add(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
    > __dl_update(dl_b, -((s32)tsk_bw / cpus));
    > }
    >
    > +static inline unsigned long rd_capacity(int cpu);
    > +
    > static inline
    > -bool __dl_overflow(struct dl_bw *dl_b, int cpus, u64 old_bw, u64 new_bw)
    > +bool __dl_overflow(struct dl_bw *dl_b, int cpu, u64 old_bw, u64 new_bw)
    > {
    > return dl_b->bw != -1 &&
    > - dl_b->bw * cpus < dl_b->total_bw - old_bw + new_bw;
    > + cap_scale(dl_b->bw, rd_capacity(cpu)) <
    > + dl_b->total_bw - old_bw + new_bw;
    > }
    >

    I don't think this is strictly equivalent to what we have now for the SMP
    case. 'cpus' used to come from dl_bw_cpus(), which is an ugly way of
    writing

    cpumask_weight(rd->span AND cpu_active_mask);

    The rd->cpu_capacity_orig field you added gets set once per domain rebuild,
    so it also happens in sched_cpu_(de)activate() but is separate from
    touching cpu_active_mask. AFAICT this mean we can observe a CPU as !active
    but still see its capacity_orig accounted in a root_domain.


    > extern void init_dl_bw(struct dl_bw *dl_b);

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