IPDRM 2016 Keynote

Henry Hoffmann

Abstract: Summary form only given. Approximate computing has recently received a great deal of attention from a range of researchers including circuit designers, hardware architects, and programming language designers. This talk discusses some of the recent trends in approximate computing and then argues that really approximation is something that application developers have been doing all along. So, perhaps the biggest insight in the current trend in approximation is that by exposing the things applications developers approximate to the rest of the computer system, there is the opportunity to do even more. We then investigate one of those things that is possible when the computer system can coordinate with an approximate application. Specifically, we discuss JouleGuard: a framework that coordinates approximate applications with system resource usage to meet user-defined energy goals with control theoretic formal guarantees. We show results of using JouleGuard on three different platforms (a mobile, tablet, and server) with eight different approximate applications created from two different frameworks. We find that JouleGuard respects energy budgets, provides near optimal accuracy, adapts to phases in application workload, and provides better outcomes than application approximation or system resource adaptation alone. JouleGuard is general with respect to the applications and systems it controls, making it a suitable runtime for a number of approximate computing frameworks.