Scheduling vs Communication in PELCR

PELCR is an environment for lambda-terms reduction on parallel/distributed computing systems. The computation performed in this environment is a distributed graph rewriting and a major optimization to achieve efficient execution consists of a message aggregation technique exhibiting the potential for strong reduction of the communication overhead. In this paper we discuss the interaction between the effectiveness of aggregation and the schedule sequence of rewriting operations. Then we present a Priority Based (BP) scheduling algorithm well suited for the speci c aggregation technique. Results on a classical benchmark lambda-term demonstrate that PB allows PELCR to achieve up to 88% of the ideal speedup while executing on a shared memory parallel architecture.