Parallel FFT on ATM‐based networks of workstations

Abstract

We consider parallel computing on a network of workstations using a connection-oriented protocol (e.g., Asynchronous Transfer Mode) for data communication. In a connection-oriented protocol, a virtual circuit of guaranteed bandwidth is established for each pair of communicating workstations. Since all virtual circuits do not have the same guaranteed bandwidth, a parallel application must deal with the unequal bandwidths between workstations. Since most works in the design of parallel algorithms assume equal bandwidths on all the communication links, they often do not perform well when executed on networks of workstations using connection-oriented protocols. In this paper, we first evaluate the performance degradation caused by unequal bandwidths on the execution of conventional parallel algorithms such as the fast Fourier transform and bitonic sort. We then present a strategy based on dynamic redistribution of data points to reduce the bottlenecks caused by unequal bandwidths. We also extend this strategy to deal with processor heterogeneity. Using analysis and simulation we show that there is a considerable reduction in the runtime if the proposed redistribution strategy is adopted. The basic idea presented in this paper can also be used to improve the runtimes of other parallel applications in connection-oriented environments.