On Tue, Jan 15, 2019 at 10:15:00AM +0000, Patrick Bellasi wrote: > +/* > + * Number of utilization clamp buckets. > + * > + * The first clamp bucket (bucket_id=0) is used to track non clamped tasks, > i.e. > + * util_{min,max} (0,SCHED_CAPACITY_SCALE). Thus we allocate one more bucket > in > + * addition to the compile time configured number. > + */ > +#define UCLAMP_BUCKETS (CONFIG_UCLAMP_BUCKETS_COUNT + 1) > + > +/* > + * Utilization clamp bucket > + * @value: clamp value tracked by a clamp bucket > + * @bucket_id: the bucket index used by the fast-path > + * @mapped: the bucket index is valid > + * > + * A utilization clamp bucket maps a: > + * clamp value (value), i.e. > + * util_{min,max} value requested from userspace > + * to a: > + * clamp bucket index (bucket_id), i.e. > + * index of the per-cpu RUNNABLE tasks refcounting array > + * > + * The mapped bit is set whenever a task has been mapped on a clamp bucket > for > + * the first time. When this bit is set, any: > + * uclamp_bucket_inc() - for a new clamp value > + * is matched by a: > + * uclamp_bucket_dec() - for the old clamp value > + */ > +struct uclamp_se { > + unsigned int value : bits_per(SCHED_CAPACITY_SCALE); > + unsigned int bucket_id : bits_per(UCLAMP_BUCKETS); > + unsigned int mapped : 1; > +};
Do we want something like: BUILD_BUG_ON(sizeof(struct uclamp_se) == sizeof(unsigned int)); And/or put a limit on CONFIG_UCLAMP_BUCKETS_COUNT that guarantees that ?