Abstract

In this paper we introduce the ConSet communication model for distributed memory parallel computers. The communication needs of an application program can be satisfied by some arbitrary set of connections which are partitioned into discrete phases. A communication context switch is used to select the active phase. We present an implementation of the ConSet model on the iWarp and describe its performance characteristics, contrasting it to a message passing implementation on the same machine. Our implementation demonstrates how one existing parallel computer can function as a “reconfigurable network ” without needing a new processor interconnect technology. The ConSet model works best when communication patterns can be optimized at compile time. We examine the interactions of the target architecture with the algorithmic problems encountered designing a communication compiler to effectively partition, route, and schedule connections. We built a prototype communication compiler for our iWarp implementation, and are using it to generate iWarp code. Looking at basic communication patterns as well as patterns generated by an iterative finite element PDE solver, we compare ConSet’s performance (using the compiler’s schedules) to that of message passing. Our experiments suggestthat ConSet communication offers a performance advantage over messagepassing in applications where the communication pattern is known at compile time. 1

Citations