Checkpoint Aware Hybrid Cache Architecture for NV Processor in Energy Harvesting Powered Systems

Energy harvesting is one of the most promising battery alternatives to power future generation embedded systems in Internet of Things (IoT). However, energy harvesting powered embedded systems suffer from frequent execution interruption due to unstable energy supply. To bridge intermittent program execution across different power cycles, non-volatile processor (NVP) was proposed to checkpoint register contents during power failure. Together with register contents, the cache contents also need to be preserved during power failure. While pure non-volatile memory (NVM) based cache is an intuitive option, it suffers from inferior performance due to high write latency and energy overhead. In this paper, we will propose replacement and checkpoint policies for SRAM and NVM based hybrid cache in NVPs whose execution is interrupted frequently. Checkpointing aware cache replacement polices and smart checkpointing polices are proposed to achieve satisfactory performance and efficient checkpointing upon a power failure and fast resumption when power returns. The experimental results show that the proposed architectures and polices outperform existing cache architectures for NVPs.