Performance evaluation of Optical Packet Switches on high performance applications

Abstract

This paper analyzes the performance impact of Optical Packet Switches (OPS) on parallel HPC applications. Because these devices cannot store light, in case of a collision for accessing the same output port in the switch only one packet can proceed and the others are dropped. The analysis focuses on the negative impact of packet collisions in the OPS and subsequent re-transmissions of dropped packets. To carry out this analysis we have developed a system simulator that mimics the behavior of real HPC application traffic and optical network devices such as the OPS. By using real application traces we have analyzed how message re-transmissions could affect parallel executions. In addition, we have also developed a methodology that allows to process applications traces and determine packet concurrency. The concurrency evaluates the amount of simultaneous packets that applications could transmit in the network. Results have shown that there are applications that can benefit from the advantages of OPS technology. Taking into account the applications analyzed, these applications are the ones that show less than 1% of packet concurrency; whereas there are other applications where their performance could be impacted by up to 65%. This impact is mostly dependent on application traffic behavior that is successfully characterized by our proposed methodology.