Re: [PATCH v10 13/16] sched/core: uclamp: Propagate parent clamps

Tejun Heo
2019-06-24T17:46:13Z

Hello, Patrick.

On Mon, Jun 24, 2019 at 06:34:05PM +0100, Patrick Bellasi wrote:
> > On Fri, Jun 21, 2019 at 09:42:14AM +0100, Patrick Bellasi wrote:
> > > Since it can be interesting for userspace, e.g. system management
> > > software, to know exactly what the currently propagated/enforced
> > > configuration is, the effective clamp values are exposed to user-space
> > > by means of a new pair of read-only attributes
> > > cpu.util.{min,max}.effective.
> >
> > Can we not add the effective interface file for now?
>
> You mean just the (read-only) user-space API right?

Yeah.

> I found it quite convenient, even just for debugging.
> Moreover it allows a container to know what it's exactly getting...

I fully agree.

> > I don't think it's a bad idea but would like to think more about it.
> > For cpuset, it was needed because configuration was so interwoven
> > with the effective masks, but we don't generally do this for other
> > min/max or weight knobs, all of which have effective hierarchical
> > values and I'm not quite sure about adding .effective for all of
> > them.
> > It could be that that's what we end up doing eventually but
> > I'd like to think a bit more about it.
>
> ... but I see your point and, since it's not strictly required, I
> think we can drop it in v11. Will check better if it's of any use
> apart from debugging/testing support.

Yeah, I just wanna figure out a plan which works for other controllers
too. It could be that the right thing to do is just adding .effective
to everything but idk I need to think more about it.

Thanks.

--
tejun