Wormhole optical network: a new architecture to solve long diameter problem in exascale computer

Abstract

The exascale computer will be built in the near future thanks to rapid innovations in semiconductor logic, memory, architectures, interconnections and other essential technologies. It is difficult to design an interconnection network that combines high performance with low power consumption. Therefore, building an interconnection network with high cost performance plays a critical role in building such a large scale system. Currently, torus-interconnected network like 6D-Torus possesses suitable properties for the petascale computer. However, the diameter within the torus-interconnected network is too long to achieve efficient global communication in the exascale computer. In addition, a direct connection method is not adaptive to the diverse characteristics of traffic. Here, we propose an architecture called Wormhole Optical Network (WON) for the exascale computer which is based on optical circuit switching. WON was designed to fully integrate into the electrical network of 6D-Torus. WON allows for the use of three novel technologies, namely the dynamic topology with optical links, algorithm of cross dimension order routing, and strategy of flow control for deadlock-free. We evaluated WON using both a prototype system and a simulator for the exascale computer. Our analysis shows that compared to the traditional electrical architecture, WON architecture reduced the time of data communication by 14–29% on exascale, a result obtained for a wide selection of diverse applications. Through enabling an SDN controller to adjust topology, WON maintains high utilization of optical links for inter-process communication from diverse applications. Further, we quantified WON’s flexibility of job deployment for mitigating hotspot traffic. We show that WON reduced latency by 20–35% in the large-range deployment and improved throughput by 30% in the long-distance deployment.