On 13-Mar 14:40, Peter Zijlstra wrote: > 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. Wondering if compilers cannot do these optimizations... but yes, looks cool and will do it in v8, thanks. > > +} > > + > > +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; > } > } Yes, the for looks better, but perhaps like that: unsigned int bucket_id = UCLAMP_BUCKETS; /* * Both min and max clamps are MAX aggregated, thus the topmost * bucket with some tasks defines the rq's clamp value. */ for (; bucket_id >= 0; --bucket_id) { if (!bucket[bucket_id].tasks) continue; max_value = bucket[bucket_id].value; break; } ... just to save a {} block. > > + WRITE_ONCE(rq->uclamp[clamp_id].value, max_value); > > +} -- #include <best/regards.h> Patrick Bellasi