Hardware based frequency/voltage control of voltage frequency island systems

The ability to do fine grain power management via local voltage selection has shown much promise via the use of voltage/ frequency islands (VFIs). VFI-based designs combine the advantages of using fine-grain speed and voltage control for reducing energy requirements, while allowing for maintaining performance constraints. We propose a hardware based technique to dynamically change the clock frequencies and potentially voltages of a VFI system driven by the dynamic workload. This technique tries to change the frequency of a synchronous island such that it will have efficient power utilization while satisfying performance constraints. We propose a hardware design that can be used to change the frequencies of various synchronous islands interconnected together by mixed-clock/mixed-voltage FIFO interfaces. Results show up to 65% power savings for the set of benchmarks considered with no loss in throughput.