Excerpts from Yury Norov's message of November 28, 2021 1:56 pm: > In many cases people use bitmap_weight()-based functions like this: > > if (num_present_cpus() > 1) > do_something(); > > This may take considerable amount of time on many-cpus machines because > num_present_cpus() will traverse every word of underlying cpumask > unconditionally. > > We can significantly improve on it for many real cases if stop traversing > the mask as soon as we count present cpus to any number greater than 1: > > if (num_present_cpus_gt(1)) > do_something(); > > To implement this idea, the series adds bitmap_weight_{eq,gt,le} > functions together with corresponding wrappers in cpumask and nodemask.
There would be no change to callers if you maintain counters like what is done for num_online_cpus() today. Maybe some fixes to arch code that does not use set_cpu_possible() etc APIs required, but AFAIKS it would be better to fix such cases anyway. Thanks, Nick _______________________________________________ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc