ABSTRACT
This chapter presents a design technique that dynamically varies the supply voltage to only provide high throughput when required, as most portable devices require peak throughput only some fraction of the time. Programmable voltage regulators can be used, but they are not designed to continuously vary their output voltage and degrade the overall system energy efficiency. Processors generally operate at a fixed voltage and require a regulator to tightly control voltage supply variation. The voltage scheduler is a new operating system component for use in a dynamic voltage scaling system. The basic voltage scheduler algorithm determines the optimal clock frequency by combining the computation requirements of all the active tasks in the system, and ensuring that all latency requirements are met given the task ordering of the temporal scheduler. The delay of complementary metal oxide semiconductor circuits tracks over voltage such that functional verification is only required at one operating voltage.
