An analysis of the performance impacts of lookahead execution in the conversation scheme

The lookahead execution approach, which allows early finishing participant processes to exit from a conversation before other participants finish their conversation activities, is adopted as a fundamental approach to reducing the synchronization overhead. Queueing network models are developed for both the system operating under the basic conversation scheme and the system operating under the conversation scheme extended with the lookahead capability. Based on the models, various performance indicators such as the system throughput, the average number of processors idling inside a conversation due to the synchronization required, and the average time spent in a conversation are evaluated numerically for different application environments. The performances under the extended scheme are compared to those under the basic conversation scheme. The results provide insights into the extent of benefits that can be brought in by the lookahead execution approach