Software assisted non-volatile register reduction for energy harvesting based cyber-physical system

Wearable devices are important components as information collector in many cyber-physical systems. Energy harvesting instead of battery is a better power source for these wearable devices due to many advantages. However, harvested energy is naturally unstable and program execution will be interrupted frequently. Non-volatile processors demonstrate promising advantages to back up volatile state before the system energy is depleted. However, it also introduces non-negligible energy and area overhead. Since the chip size is a vital factor for wearable devices, in this work, we target non-volatile register reduction for application-specific systems. We propose to analyze the application program and determine efficient backup positions, by which the necessary non-volatile register file size can be significantly reduced. The evaluation results deliver an average of 62.9% reduction on non-volatile register file size for stack backup, with negligible storage overheads.