Redesign System Software for Heterogeneous Mobile Devices

April 4, 2014
Felix Xiaozhu Lin | Rice University

The computer industry has hit the power and thermal wall. This is most obvious in mobile devices due to their tight thermal and battery constraints. To overcome such obstacles, mobile devices have pioneered the adoption of heterogeneous compute resources. The resulting system architectures, while having the potential for high energy efficiency, usually lack hardware cache coherence and therefore invalidate the basic assumptions made by today’s mobile software stack.

Towards enabling the software stack to easily exploit heterogeneous processors for high energy efficiency, we construct system software that realizes two key abstractions – coherent memory and a unified OS namespace. The system software consists of two main components: 1) A user-level runtime named Reflex that provides user programs with software coherence, built around an unconventional invariant that guarantees efficiency; 2) An OS named K2, the outcome of refactoring a legacy OS, spans most of its components transparently across incoherent processors while running a small set of components as independent instances. Overall, the system software eases programming and improves energy efficiency by one order of magnitude.

In this talk, I will outline the system design, highlight principles distilled from the design, and share our experiences in hardware and software hacking. Finally, I will identify new research directions as heterogeneity is reshaping the entire landscape of computing.

Speaker Details

Felix Xiaozhu Lin is a PhD candidate at Rice University. He cares about low-level software for exploiting emerging hardware features. His dissertation focuses on mobile and wearable systems – the early adopters of heterogeneous hardware – and strives to meet users’ ever-increasing (and sometimes unreasonable) demands: lightning fast UI, always-on devices, and long-lasting battery. One of his recent projects, the K2 mobile OS, is available at www.k2os.org.

He received BS and MS from Tsinghua University; during his PhD study, he has worked at Nokia Research Hollywood, IBM Research Austin, and Microsoft Research.