Evaluation of the data vortex photonic all-optical path interconnection network for next-generation supercomputers.

摘要

Today's supercomputers employ the fastest processors incorporating the latest VLSI technology. Unfortunately, usable system performance is often limited by excessive interprocessor latency. To overcome this bottleneck, this thesis explores the use of all-optical path interconnection networks using a new topology defined by Coke Reed [31]. This work overcomes limitations of previous optical networks through a novel use of defection routing to minimize latency and allow more processors to collaborate on the same application and dataset. In this thesis research, the data vortex is formally characterized and tested for performance. Extra angles serve as "virtual buffers" to provide required system performance, even under asymmetric mode operation. The data vortex is compared to two well-known interconnection networks (omega and butterfly) using metrics of average latency and message acceptance rate. The data vortex is shown to outperform the comparison networks, with a 20-50% higher acceptance rate and comparable average latency. The impact of angle size is also studied, and a new, synchronous mode of operation is proposed where additional angles are added to increase the virtual buffering of the network. The tradeoff between virtual buffering and angle resolution backpressure is explored, and an optimal point is found at the 1:6 I/O to non-I/O (virtual buffering) angle ratio. The new mode and optimal angle count are used to form data vortex networks that perform as well as larger networks with fewer total nodes. Finally, hierarchical layering with data vortex clusters is proposed and compared to a single-level data vortex. In today's technology, similar performance is attained at high network communication locality loads (>2/3), and a 19% latency reduction is obtained at the highest locality loads (>95%) for current optical switching technology. For projected future technology, the clustered system is shown to yield up to a 55% reduction in latency for applications with 2/3 or better locality.