On 12/09/20 00:04, Li, Aubrey wrote:
>>> +++ b/include/linux/sched/topology.h
>>> @@ -65,8 +65,21 @@ struct sched_domain_shared {
>>> atomic_t ref;
>>> atomic_t nr_busy_cpus;
>>> int has_idle_cores;
>>> + /*
>>> + * Span of all idle CPUs in this domain.
>>> + *
>>> + * NOTE: this field is variable length. (Allocated dynamically
>>> + * by attaching extra space to the end of the structure,
>>> + * depending on how many CPUs the kernel has booted up with)
>>> + */
>>> + unsigned long idle_cpus_span[];
>>
>> Can't you use cpumask_var_t and zalloc_cpumask_var() instead?
>
> I can use the existing free code. Do we have a problem of this?
>
Nah, flexible array members are the preferred approach here; this also
means we don't let CONFIG_CPUMASK_OFFSTACK dictate where this gets
allocated.
See struct numa_group, struct sched_group, struct sched_domain, struct
em_perf_domain...
>>
>> The patch looks useful. Did it help you with any particular workload? It'd be
>> good to expand on that in the commit message.
>>
> Odd, that included in patch v1 0/1, did you receive it?
>
> Thanks,
> -Aubrey
