Re: [Xen-devel] [PATCH v2 10/48] xen/sched: add scheduler helpers hiding vcpu

[Jan Beulich <jbeulich@xxxxxxxx>]

On 09.08.2019 16:57, Juergen Gross wrote:
> Add the following helpers using a sched_unit as input instead of a
> vcpu:
> 
> - is_idle_unit() similar to is_idle_vcpu()
> - is_unit_online() similar to is_vcpu_online()
> - unit_runnable() like vcpu_runnable()

Since for vCPU-s within a unit the return values can vary, I think
it would be nice if you made explicit here what the unit-wide return
values are meant to mean in such a case (and why the chosen
alternative is better than the other one).

> - sched_set_res() to set the current processor of an unit
> - sched_unit_cpu() to get the current processor of an unit

What is "the processor of a unit" when there are multiple
entities within a unit, and hence multiple processors needed
in order to run the unit?

> --- a/xen/include/xen/sched-if.h
> +++ b/xen/include/xen/sched-if.h
> @@ -59,6 +59,62 @@ static inline void set_sched_res(unsigned int cpu, struct 
> sched_resource *res)
>      per_cpu(sched_res, cpu) = res;
>  }
>  
> +static inline bool is_idle_unit(const struct sched_unit *unit)
> +{
> +    return is_idle_vcpu(unit->vcpu_list);
> +}
> +
> +static inline bool is_unit_online(const struct sched_unit *unit)
> +{
> +    return is_vcpu_online(unit->vcpu_list);
> +}
> +
> +static inline bool unit_runnable(const struct sched_unit *unit)
> +{
> +    return vcpu_runnable(unit->vcpu_list);
> +}
> 
> +static inline void sched_set_res(struct sched_unit *unit,
> +                                 struct sched_resource *res)
> +{
> +    unit->vcpu_list->processor = res->processor;
> +    unit->res = res;
> +}
> +
> +static inline unsigned int sched_unit_cpu(struct sched_unit *unit)
> +{
> +    return unit->res->processor;
> +}
> +
> +static inline void sched_set_pause_flags(struct sched_unit *unit,
> +                                         unsigned int bit)
> +{
> +    __set_bit(bit, &unit->vcpu_list->pause_flags);
> +}
> +
> +static inline void sched_clear_pause_flags(struct sched_unit *unit,
> +                                           unsigned int bit)
> +{
> +    __clear_bit(bit, &unit->vcpu_list->pause_flags);
> +}
> +
> +static inline void sched_set_pause_flags_atomic(struct sched_unit *unit,
> +                                                unsigned int bit)
> +{
> +    set_bit(bit, &unit->vcpu_list->pause_flags);
> +}
> +
> +static inline void sched_clear_pause_flags_atomic(struct sched_unit *unit,
> +                                                  unsigned int bit)
> +{
> +    clear_bit(bit, &unit->vcpu_list->pause_flags);
> +}

And with the above - are some/all of these going to remain like
this, or will they gain for_each-style loops later?

Jan

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