Process Cooperation in Multiple Message Broadcast

Abstract

We present a process cooperation algorithm for broadcasting m messages among n processes, m ≥ 1, n ≥ 1, in one-port fully-connected communication systems. In this algorithm, the n processes are organized into $2^{\lfloor \log n \rfloor}$ one- or two-process units. Messages are broadcast among the units according to a basic communication schedule. Processes in each two-process unit cooperate to carry out the basic schedule in a way that at any step, either process has at most one message that the other has not received. This algorithm completes the broadcast in ⌈logn ⌉ + m − 1 communication steps, which is theoretically optimal. Empirical study shows that it outperforms other widely used algorithms significantly when the data to broadcast is large. Efficient communication schedule construction is a salient feature of this algorithm. Both the basic schedule and the cooperation schedule are constructed in O(logn) bitwise operations on process ranking.