Messages in this thread | | | Date | Thu, 9 Aug 2018 16:55:53 +0100 | From | Quentin Perret <> | Subject | Re: [PATCH v3 06/14] sched/cpufreq: uclamp: add utilization clamping for RT tasks |
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Hi Patrick,
On Thursday 09 Aug 2018 at 16:41:56 (+0100), Patrick Bellasi wrote: > > 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 ?
> > > 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? > > > 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 ...
> > > 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
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