Keynote Talk: The Variability Expeditions: Exploring the Software Stack for Underdesigned Computing Machines

As microelectronic devices scale down to the level molecular assemblies the resulting circuits and systems do not behave like the precisely chiseled machines with tight tolerances. Modern computing is ignorant of the variability in the behavior of underlying components from device to device, chip to chip, its wear over time, or the environment in which the computing system is placed. The ´guardbands´ used to guarantee component behavior (for power, performance) have gone to ridiculous margins accounting for as much as two-thirds of the chip area to meet performance ´specs´ and is already undermining the gains from continued device scaling. Changing the way software interacts with hardware offers the best hope to recover the advantages from process scaling. In this talk I will describe our approach and progress in the Variability Expeditions project that fundamentally rethinks the rigid, deterministic hardware-software interface, to propose a new class of computing machines that rely on an opportunistic software stack to adapt to the conditions in an underdesigned hardware.