Flexfly: enabling a reconfigurable dragonfly through silicon photonics

• DOI: 10.5555/3014904.3014924
• Publication Date: 2016-11-13
• Authors: Ke Wen; Payman Samadi; Sébastien Rumley; Christine P. Chen; Yiwen Shen; Meisam Bahadori; Keren Bergman; Jeremiah J Wilke
• Keywords: Control reconfiguration; Speedup

The Dragonfly topology provides low-diameter connectivity for high-performanceleb computing with all-to-all global links at the inter-group level. Our traffic matrix characterization of various scientific applications shows consistent mismatch between imbalanced group-to-group and uniform bandwidth allocation Dragonfly. Though adaptive routing has been proposed to utilize non-minimal paths, increased hops cross-group interference lower efficiency. This work presents a photonic architecture, Flexfly, which trades among groups using low-radix Silicon switches. With transparent optical switching, Flexfly reconfigures based on pattern, stealing additional direct communication-intensive group pairs. Simulations such as GTC, Nekbone LULESH show up 1.8x speedup over paired UGAL routing, along halved hop count latency messages. We built 32-node prototype switch connecting four demonstrated 820 ns interconnect reconfiguration time.