Adaptive dynamic checkpointing for safe efficient intermittent computing

Energy-harvesting devices have the potential to be the foundation of emerging, sensor-rich application domains where the use of batteries is infeasible, such as in space and civil infrastructure. Programming on an energy-harvesting device is difficult because the device operates only intermittently, as energy is available. Intermittent operation requires the programmer to reason about energy to understand data consistency and forward progress of their program. Energy varies with input and environment, making intermittent programming difficult. Existing systems for intermittent execution provide an unfamiliar programming abstraction and fail to adapt to energy changes forcing a compromise of either performance or assurance of forward progress. This paper presents Chinchilla, a compiler and runtime system that allows running unmodified C code efficiently on an energy-harvesting device with little additional programmer effort and no additional hardware support. Chinchilla overprovisions code with checkpoints to assure the system makes progress, even with scarce energy. Chinchilla disables checkpoints dynamically to efficiently adapt to energy conditions. Experiments show that Chinchilla improves programmability, is performant, and makes it simple to statically check the absence of non-termination. Comparing to two systems from prior work, Alpaca and Ratchet, Chinchilla makes progress when Alpaca cannot, and has 125% mean speedup against Ratchet.