Software Assisted Non-volatile Register Reduction for Energy Harvesting Based Cyber-Physical System
Mengying Zhao1, Qingan Li2, Mimi Xie3, Yongpan Liu4, Jingtong Hu3 and Chun Jason Xue1
1Department of Computer Science, City University of Hong Kong, Hong Kong
2State Key Laboratory of Software Engineering, Wuhan University, China
3School of Electrical and Computer Engineering, Oklahoma State University, USA
4Department of Electronic Engineering, Tsinghua University, China
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.
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