Optimal Broadcast in a Distributed Memory Model of Parallel

A commonly arising problem in many parallel algorithms is broadcast. Many multi-processors do not have dedicated hardware for this purpose. Therefore, a broadcast must be effected by point-to-point message passing. In KSSS93, the k-broadcast problem was formulated as follows: One processor possesses k items which it wishes to disseminate to P-1 other processors. In a step, a processor can send at most one item and receive at most one item. An item is received L steps after it is sent. The goal is to find an optimal schedule. In this paper, we improve on previous results by developing (I) an optimal solution of the general problem which makes no assumptions about L or P; and (ii) a simpler but slightly sub-optimal solution which also makes no assumptions about L or P. We also discuss the results of implementing the schemes developed on a 64-processor CM-5.