Messages in this thread | | | Subject | Re: [PATCH 2/4] sched/deadline: Improve admission control for asymmetric CPU capacities | From | Dietmar Eggemann <> | Date | Wed, 8 Apr 2020 14:26:05 +0200 |
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On 08.04.20 12:42, Valentin Schneider wrote: > > 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.
I see what you mean.
The
int dl_bw_cpus(int i) { ... for_each_cpu_and(i, rd->span, cpu_active_mask) cpus++; ... }
should be there to handle the 'rd->span &nsub cpu_active_mask' case.
We could use a similar implementation for s/cpus/capacity:
unsigned long dl_bw_capacity(int i) { ... for_each_cpu_and(i, rd->span, cpu_active_mask) cap += arch_scale_cpu_capacity(i); ... }
[...]
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