| Date | Wed, 13 Mar 2019 14:40:22 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v7 01/15] sched/core: uclamp: Add CPU's clamp buckets refcounting |
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On Fri, Feb 08, 2019 at 10:05:40AM +0000, Patrick Bellasi wrote: > +static inline unsigned int uclamp_bucket_id(unsigned int clamp_value) > +{ > + return clamp_value / UCLAMP_BUCKET_DELTA; > +} > + > +static inline unsigned int uclamp_bucket_value(unsigned int clamp_value) > +{ > + return UCLAMP_BUCKET_DELTA * uclamp_bucket_id(clamp_value);
return clamp_value - (clamp_value % UCLAMP_BUCKET_DELTA);
might generate better code; just a single division, instead of a div and mult.
> +} > + > +static inline unsigned int uclamp_none(int clamp_id) > +{ > + if (clamp_id == UCLAMP_MIN) > + return 0; > + return SCHED_CAPACITY_SCALE; > +} > + > +static inline void uclamp_rq_update(struct rq *rq, unsigned int clamp_id) > +{ > + struct uclamp_bucket *bucket = rq->uclamp[clamp_id].bucket; > + unsigned int max_value = uclamp_none(clamp_id); > + unsigned int bucket_id; > + > + /* > + * Both min and max clamps are MAX aggregated, thus the topmost > + * bucket with some tasks defines the rq's clamp value. > + */ > + bucket_id = UCLAMP_BUCKETS; > + do { > + --bucket_id; > + if (!rq->uclamp[clamp_id].bucket[bucket_id].tasks) > + continue; > + max_value = bucket[bucket_id].value; > + break;
If you flip the if condition the code will be nicer.
> + } while (bucket_id);
But you can also use a for loop:
for (i = UCLAMP_BUCKETS-1; i>=0; i--) { if (rq->uclamp[clamp_id].bucket[i].tasks) { max_value = bucket[i].value; break; } }
> + WRITE_ONCE(rq->uclamp[clamp_id].value, max_value); > +}
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