Impact of Network Fairness on the Performance of Parallel Systems
Cruz Izu, Enrique Vallejo · Proceedings of the Australasian Computer Science Week Multiconference · 2019
Execution time of parallel applications depends on the balanced execution and synchronization of all its processes. However, most interconnects exhibit significant throughput unfairness, introducing load unbalance. At high loads, such unfairness significantly degrades the performance of some nodes, and eventually the whole system. Different strategies have been developed to guarantee network fairness, fundamentally based on two different approaches: traffic prioritization in the network switches or injection throttling at the source. This work qualitatively and quantitatively compares two fairness mechanisms which are representative of these two types of explicit fairness strategies: Age arbitration, which prioritizes old packets in transit, and the SAT injection protocol, which throttles traffic to provide even access to all nodes. Multiple synthetic traffic patterns as well as parallel application loads at different transmission rates are considered in the evaluation.