Power governance circuitry is provided to control a performance level of a processing unit of a processing platform. The power governance circuitry comprises measurement circuitry to measure a current utilization of the processing unit at a current operating frequency and to determine any change in utilization or power and frequency control circuitry is provided to update the current operating frequency to a new operating frequency by determining a new target quantified power expenditure to be applied in a subsequent processing cycle depending on the determination of any change in utilization or power. A new operating frequency is selected to satisfy the new target quantified power based on a scalability function specifying a variation of a given value of utilization or power with the operating frequency. A processing platform and machine readable instructions are provided to set a new quantified target power of a processing unit.