Surviving Transient Power Failures with SRAM Data Retention

摘要

Many computing systems, such as those powered by energy harvesting or deployed in harsh working environment, may experience unpredictable and frequent transient power failures in their life time. The systems may fail to deliver correct computation results or never progress, as computation is frequently interrupted by the power failures. A possible solution could be frequently saving program states to non-volatile memory (NVM), such as using checkpoints, so that the system can incrementally progress. However, this approach is too costly, since frequent NVM writes is time and energy consuming, and may wear out the NVM device. In this work, we propose an approach to enable a system to use volatile SRAM to correctly progress in the presence of transient power failures, since SRAM is capable of retaining its data for seconds or minutes with the charge remained in the battery/capacitor after the CPU core stops at its brown-out voltage. The main problem is to validate whether the data in SRAM are actually retained during power failures. In our approach, we validate only a subset of the program states with Cyclic Redundancy Check for efficiency. The validation technique requires maintaining a backup version of the program states, which additionally provides the system with the ability to progress incrementally. We implement a run-time system with the proposed approach. Experimental results on an MSP430 platform show that the system can correctly progress on SRAM in the presence of transient power failures with low overhead.