On Thu, Mar 14, 2019 at 8:41 AM Patrick Bellasi <patrick.bellasi@xxxxxxx> wrote: > > On 14-Mar 08:29, Suren Baghdasaryan wrote: > > On Thu, Mar 14, 2019 at 7:46 AM Patrick Bellasi <patrick.bellasi@xxxxxxx> wrote: > > > On 13-Mar 14:32, Suren Baghdasaryan wrote: > > > > On Fri, Feb 8, 2019 at 2:06 AM Patrick Bellasi <patrick.bellasi@xxxxxxx> wrote: > > [...] > > > > > > The rq::uclamp::bucket[clamp_id][] array is scanned every time we need > > > > > to find a new MAX aggregated clamp value for a clamp_id. This operation > > > > > is required only when we dequeue the last task of a clamp bucket > > > > > tracking the current MAX aggregated clamp value. In these cases, the CPU > > > > > is either entering IDLE or going to schedule a less boosted or more > > > > > clamped task. > > The following: > > > > > > The expected number of different clamp values, configured at build time, > > > > > is small enough to fit the full unordered array into a single cache > > > > > line. > > will read: > > The expected number of different clamp values, configured at build time, > is small enough to fit the full unordered array into a single cache > line for the default UCLAMP_BUCKETS configuration of 7 buckets. I think keeping default to be 5 is good. As you mentioned it's a nice round number and keeping it at the minimum also hints that this is not a free resource and the more buckets you use the more you pay. Documentation might say "to fit the full unordered array into a single cache line for configurations of up to 7 buckets". > [...] > > > Got it. From reading the documentation at the beginning my impression > > was that whatever value I choose within allowed 5-20 range it would > > still fit in a cache line. To disambiguate it might be worse > > mentioning that this is true for the default value or for values up to > > 7. Thanks! > > Right, I hope the above proposed change helps to clarify that. > > -- > #include <best/regards.h> > > Patrick Bellasi
