Virtualizing Analog Mesh Computers: The Case of a Photonic PDE Solving Accelerator

Innovative processor architectures play a critical role in sustaining performance improvements under severe limitations imposed by feature size and energy consumption. The Reconfigurable Optical Computer (ROC) is one such innovative, Post-Moore's Law processor. ROC is designed to solve partial differential equations in one shot as opposed to existing solutions, which are based on costly iterative computations. This is achieved by leveraging physical properties of a mesh of optical components that behave similarly to electrical resistances. However, building large photonic arrays to accommodate arbitrarily large problems is not yet feasible. It is also possible to have problems that are smaller than the size of the accelerator array. In both cases, virtualization is necessary. In this work, we introduce an architecture and methodology for light-weight virtualization of ROC. We show that overhead from virtualization is minimal, and our experimental results show two orders of magnitude increased speed as compared to microprocessor execution while keeping errors due to virtualization under 10%.