Forget Failure: Exploiting SRAM Data Remanence for Low-overhead Intermittent Computation

Energy harvesting is a promising solution to power billions of ultra-low-power Internet-of-Things devices to enable ubiquitous computing. However, energy harvesters typically output tiny amounts of energy and, therefore, cannot continuously power devices; this leads to intermittent computing, where the energy harvester periodically charges a capacitor to sufficient voltage to power brief computation, until the capacitor's charge is drained, and the cycle repeats. To retain program state across frequent power failures, prior work proposes checkpointing program state to Non-Volatile Memory (NVM) before a power failure. Unfortunately, the most widely deployed, highest performance, and lowest cost devices employ Flash as their NVM, but the power, time, and endurance limitations of Flash writes are incompatible with the frequent NVM checkpoints of intermittent computation. The multi-year data retention of Flash is overkill for retaining program state across intermittent computing's short power-off times (e.g.,