Contention-free Complete Exchange Algorithm on Clusters

To construct a large commodity cluster, a hierarchical network is generally adopted for connecting the host machines, where a Gigabit backbone switch connects a few commodity switches with uplinks to achieve scaled bisectional bandwidth. This type of interconnection usually results in link contention and has congestion developed at the uplink ports. Moreover, the non-deterministic delays on scheduling communication events in clusters accelerate the building up of congestion amongst these uplink ports, which lead to severe packets drop and hinder the overall performance. In this paper, we focus on the practical design of high-speed complete exchange algorithm on a commodity cluster interconnected by a hierarchical Ethernet-based network. With the use of some architectural characteristics in optimizing the performance of a complete exchange algorithm, we introduce a congestion control mechanism global windowing that monitors and regulates the traffic load, together with a permutation scheme reorder scheme that effectively alleviates the congestion problem. We evaluate the modified algorithm and compare its performance with the original algorithm and a well-known algorithm in a PC cluster connected by various types of switches, including Gigabit Ethernet, input-buffered and shared-memory Fast Ethernet switches.