Priority based real-time communication for large scale wormhole networks

As advances are made in parallel processing technology, an increasing number of real-time applications are being developed for large-scale parallel processors. Since the wormhole network is a popular communication system used in the new generation of large-scale parallel multiprocessors, real-time communication support on wormhole networks becomes an important issue. We evaluate a priority mapping scheme, a priority adjustment scheme and a message dropping method for large-scale real-time wormhole networks. The priority mapping scheme embeds the timing property of a message into a priority for flow control decisions. The priority adjustment scheme dynamically modifies the priority of a message as the timing property of the message changes. The tardy messages, which miss their deadlines, are removed from the network by the message dropping method. Simulation studies show that the schemes outperform the conventional flow control scheme implemented in general purpose wormhole networks, and the schemes provide desirable performance when the size of the parallel system increases