Hi Patrick,

On Thursday 09 Aug 2018 at 16:41:56 (+0100), Patrick Bellasi wrote:

quoted

IIUC, not far below this you should still have something like:

	if (rt_rq_is_runnable(&rq->rt))
		return max;

Do you mean that when RT tasks are RUNNABLE we still want to got to
MAX? Not sure to understand... since this patch is actually to clamp
the RT class...

Argh, reading my message again it wasn't very clear indeed. Sorry about
that ...

What I'm try to say is that your patch does _not_ remove the snippet of code
above from sugov_get_util(). So I think that when a RT task is runnable,
you will not reach the end of the function where the clamping is done.
And this is not what you want AFAICT.

Does that make any sense ?

quoted

So you won't reach the actual clamping code at the end of the function
when a RT task is runnable no?

... mmm... no... this patch is to clamp RT tasks... Am I missing
something?

quoted

Also, I always had the feeling that the default for RT should be
util_min == 1024, and then users could decide to lower the bar if they
want to.

Mmm... good point! This would keep the policy unaltered for RT tasks.

I want to keep sched class specific code in uclamp at minimum but
likely this should be achievable by just properly initializing the
task-specific util_min for RT tasks, if the original task has
UCLAM_NOT_VALID.

+1, it'd be nice to keep the cross-class mess to a minimum IMO. But
hopefully this RT thing isn't too ugly to implement ...

quoted

For the specific case of RT, that feels more natural than
applying a max util clamp IMO. What do you think ?

I'll look better into this for the next posting!

Sounds good :-)

Thanks,
Quentin