Predictable communication on unpredictable networks: Implementing BSP over TCP/IP

The BSP cost model measures the cost of communication using a single architectural parameter, g, which measures permeability of the network to continuous traffic. Architectures, typically networks of workstations, pose particular problems for high-performance communication because it is hard to achieve high throughput, and even harder to do so predictably. Yet both of these are required for BSP to be effective. We present a technique for controlling applied communication load that achieves both. Traffic is presented to the communication network at a rate chosen to maximise throughput and minimise its variance. Performance improvements as large as a factor of two over MPI can be achieved.