Abstract: The present disclosure relates to a technique for varying the frequency of operation of one or more cores in a processor device capable of operating at different frequencies and voltages. A method aspect of this technique includes executing one or more tasks on the at least one processor core, wherein the tasks are grouped into groups, monitoring usage of the at least one processor core by tasks in the groups on a per group basis, aggregating the monitored usage of the at least one processor core by individual groups across the groups to derive a load parameter indicative of the combined usage of the at least one processor core by the tasks in the groups, selecting a frequency of operation based upon the load parameter, and changing the frequency of operation of the at least one processor core to the selected frequency of operation.