Messages in this thread | | | Date | Wed, 23 Jan 2019 14:51:06 +0000 | From | Patrick Bellasi <> | Subject | Re: [PATCH v6 10/16] sched/core: Add uclamp_util_with() |
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On 23-Jan 14:33, Peter Zijlstra wrote: > On Tue, Jan 15, 2019 at 10:15:07AM +0000, Patrick Bellasi wrote: > > +static __always_inline > > +unsigned int uclamp_util_with(struct rq *rq, unsigned int util, > > + struct task_struct *p) > > { > > unsigned int min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value); > > unsigned int max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value); > > > > + if (p) { > > + min_util = max(min_util, uclamp_effective_value(p, UCLAMP_MIN)); > > + max_util = max(max_util, uclamp_effective_value(p, UCLAMP_MAX)); > > + } > > + > > Like I think you mentioned earlier; this doesn't look right at all.
What we wanna do here is to compute what _will_ be the clamp values of a CPU if we enqueue *p on it.
The code above starts from the current CPU clamp value and mimics what uclamp will do in case we move the task there... which is always a max aggregation.
> Should that not be something like: > > lo = READ_ONCE(rq->uclamp[UCLAMP_MIN].value); > hi = READ_ONCE(rq->uclamp[UCLAMP_MAX].value); > > min_util = clamp(uclamp_effective(p, UCLAMP_MIN), lo, hi); > max_util = clamp(uclamp_effective(p, UCLAMP_MAX), lo, hi);
Here you end up with a restriction of the task clamp (effective) clamps values considering the CPU clamps... which is different.
Why do you think we should do that?... perhaps I'm missing something.
-- #include <best/regards.h>
Patrick Bellasi
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