Tortola: Addressing Tomorrow’s Computing Challenges through Hardware/Software Symbiosis

Until recently, the vast majority of research efforts in optimizing computer systems have targeted a single logical “layer” in isolation: application code, operating systems, virtual machines, microarchitecture, or circuits. However, we are reaching the limits of the solutions than we can provide by targeting a single design layer in isolation. The Tortola project explores a symbiotic relationship between a virtual machine and the host microarchitecture to solve crosscutting concerns in the areas of power, reliability, security, and performance using both hardware and software extensions. We have demonstrated the effectiveness of our approach on the well-known dI/dt problem, where we successfully stabilized the voltage fluctuations of the CPU’s power supply by transforming the source code of the executing application using feedback from hardware. This paper and accompanying talk will motivate our notion of symbiotic program optimization, discuss various applications, and detail our experiences in solving the dI/dt problem using a holistic approach.