Performance of a Cluster of PCI Based UltraSparc Workstations Interconnected with SCI

SCI is based on unidirectional point-to-point links forming ringlets that can be connected with switches to allow further scaling. This paper presents performance results from running on a number of differently configured SCI clusters. The SCI technology used is Dolphin’s second generation PCI/SCI adapter based on the LC-2 LinkController chip as well as a new 4 port, LC-2 based switch. Nodes are UltraSparcs running Solaris 2.5.1 as the operating system. Results show latencies down to 2.9μs for remote stores, and bandwidths up to 80 Mbytes/s into a single system. Network throughput of more than 270 Mbytes/s (8 node system) is demonstrated. Results indicate that the new LC-2 eliminates a number of problems with the earlier LC-1 chip in addition to increasing peak performance. With its flexible building blocks this technology should also make it possible to construct systems with a large number of nodes, pushing I/O adapter based SCI interconnects forward as a promising system area network technology.