We compared the message passing library Parallel Virtual Machine (PVM) with the distributed shared memory system TreadMarks, on networks of workstations. We presented the performance of nine applications, including Water and Barnes-Hut from the SPLASH benchmarks; 3-D FFT, Integer Sort and Embarrassingly Parallel from the NAS benchmarks; ILINK, a widely used genetic analysis program; and SOR, TSP, and QuickSort.TreadMarks performed nearly identical to PVM on computation bound programs, such as the Water simulation of 1728 molecules. For most of the other applications, including ILINK, TreadMarks performed within 75% of PVM with 8 processes. The separation of synchronization and data transfer, and additional messages to request updates for data in the invalidate-based shared-memory protocol were two of the reasons for TreadMarks's lower performance. TreadMarks also suffered from extra data communication due to false sharing. Moreover, PVM benefited from the ability to aggregate scattered data in a single message.
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