Improving protocol performance by dynamic control of communication resources

A problem frequently faced by complex distributed applications is to control the interaction of their communication and computational activities such that they jointly adhere to desired performance and timing requirements. This research concerns communication infrastructures able to cope with the varying processing and QoS/sup 1/ requirements imposed on them by application programs. Specifically, we describe and evaluate COMM/sup adapt/, a communication infrastructure enabling the on-line adaptation of a protocol's resource usage to currently available resources and application requirements. The key feature of COMM/sup adapt/ is its dynamic (auto-)configurability, which is its support of on-line configuration transparent to application programs. Such configuration is performed by a heuristic that accommodates changes in a connection's resource requirements by reallocating resources based on its knowledge of actual resource usage by other active connections. The heuristic's design and implementation are based on extensive investigations of the manner in which alternative assignments of protocol tasks to underlying processing resources can influence program-level latency and throughput requirements.