Re: [PATCH v4 08/16] sched/core: uclamp: propagate parent clamps

Suren Baghdasaryan
2018-09-12T15:56:27Z

On Wed, Sep 12, 2018 at 5:51 AM, Patrick Bellasi
<patrick.bellasi@arm.com> wrote:
> On 08-Sep 20:02, Suren Baghdasaryan wrote:
>> On Tue, Aug 28, 2018 at 6:53 AM, Patrick Bellasi
>> <patrick.bellasi@arm.com> wrote:
>
> [...]
>
>> > + cpu.util.min.effective
>> > + A read-only single value file which exists on non-root cgroups and
>> > + reports minimum utilization clamp value currently enforced on a task
>> > + group.
>> > +
>> > + The actual minimum utilization in the range [0, 1023].
>> > +
>> > + This value can be lower then cpu.util.min in case a parent cgroup
>> > + is enforcing a more restrictive clamping on minimum utilization.
>>
>> IMHO if cpu.util.min=0 means "no restrictions" on UCLAMP_MIN then
>> calling parent's lower cpu.util.min value "more restrictive clamping"
>> is confusing. I would suggest to rephrase this to smth like "...in
>> case a parent cgroup requires lower cpu.util.min clamping."
>
> Right, it's slightly confusing... still I would like to call out that
> a parent group can enforce something on its children. What about:
>
> "... a parent cgroup allows only smaller minimum utilization values."
>
> Is that less confusing ?

SGTM.

>
> Otherwise I think your proposal could work too.
>
> [...]
>
>> > #ifdef CONFIG_UCLAMP_TASK_GROUP
>> > +/**
>> > + * cpu_util_update_hier: propagete effective clamp down the hierarchy
>>
>> typo: propagate
>
> +1
>
> [...]
>
>> > + * Skip the whole subtrees if the current effective clamp is
>> > + * alredy matching the TG's clamp value.
>>
>> typo: already
>
> +1
>
>
> Cheers,
> Patrick
>
> --
> #include <best/regards.h>
>
> Patrick Bellasi