Policies for Dynamic Clock Scheduling

Pocket computers are beginning to emerge that provide sufficient processing capability and memory capacity to run traditional desktop applications and operating systems on them. The increasing demand placed on these systems by software is competing against the continuing trend in the design of low-power microprocessors towards increasing the amount of computation per unit of energy. Consequently, in spite of advances in low-power circuit design, the microprocessor is likely to continue to account for a significant portion of the overall power consumption of pocket computers. This paper investigates clock scaling algorithms on the Itsy, an experimental pocket computer that runs a complete, functional multitasking operating system (a version of Linux 2.0.30). We implemented a number of clock scaling algorithms that are used to adjust the processor speed to reduce the power used by the processor. After testing these algorithms, we conclude that currently proposed algorithms consistently fail to achieve their goal of saving power while not causing user applications to change their interactive behavior.