Compiler Support for Long-life, Low-overhead Intermittent Computation on Energy Harvesting Flash-based Devices

With the advent of energy harvesters, supporting fast and efficient computation on energy harvesting devices has become a key challenge in the field of energy harvesting on ubiquitous devices. Computation on energy harvesting devices is equivalent to spreading the execution time of a lasting application over short, frequent cycles of power. However, we must ensure that results obtained from intermittently executing an application do produce results that are congruent to those produced by executing the application on a device with a continuous source of power. The current state-of-the-art systems that enable intermittent computation on energy harvesters make use of novel compiler analysis techniques as well as on-board hardware on devices to measure the energy remaining for useful computation. However, currently available programming models, which mostly target devices with FRAM as the NVM, would cause failure on devices that employ the Flash as primary NVM, thereby resulting in a non-universal solution that is restricted by the choice of NVM. This is primarily the result of the Flash's limited read/write endurance.

This research aims to contribute to the world of energy harvesting devices by providing solutions that would enable intermittent computation regardless of the choice of NVM on a device by utilizing only the SRAM to save state and perform computation. Utilizing the SRAM further reduces run-time overhead as SRAM reads/writes are less costlier than NVM reads/writes. Our proposed solutions rely on programmer-guidance and compiler analysis to correct and efficient intermittent computation. We then extend our system to provide a complete compiler-based solution without programmer intervention. Our system is able to run applications that would otherwise render any device with Flash as NVM useless in a matter of hours.