Supporting peripherals in intermittent systems with just-in-time checkpoints

Batteryless energy-harvesting devices have the potential to be the foundation of applications for which batteries are infeasible. Just-In-Time checkpointing supports intermittent execution on energy-harvesting devices by checkpointing processor state right before a power failure. While effective for software execution, Just-In-Time checkpointing remains vulnerable to unrecoverable failures involving peripherals (e.g., sensors and accelerators) because checkpointing during a peripheral operation may lead to inconsistency between peripheral and program state. Additionally, a peripheral operation that uses more energy than a device can buffer never completes, causing non-termination. This paper presents Samoyed, a Just-In-Time checkpointing system that safely supports peripherals. Samoyed correctly runs user-annotated peripheral functions by selectively disabling checkpoints and undo-logging. Samoyed guarantees progress by energy profiling, dynamic peripheral workload scaling, and a user-provided software fallback routine. Our evaluation shows that Samoyed correctly executes peripheral operations that fail with existing systems, achieving up to 122.9x speedup by using accelerators. Samoyed preserves the performance benefit of Just-In-Time checkpointing, showing 4.11x mean speedup compared to a recent possible alternative. Moreover, Samoyed's unique ability to profile energy and to dynamically scale large peripheral operations simplifies programming.