ComPaSS: A Communication Package for Scalable Software Design

Abstract

In massively parallel computers (MPCs), efficient communication among processors is critical to performance. This paper describes the initial implementation of the ComPaSS communication library to support scalable software development in MPCs. ComPaSS provides high-level global communication operations for both data manipulation and process control, many of which are based upon a small set of low-level communication primitives. The low-level operations of the ComPaSS library are provably optimal for a class of architectures representative of many commercial scalable systems, in particular those using wormhole routing and n-dimensional mesh network topologies. This paper concentrates on the multicast and multireceive components of the ComPaSS library, which are fundamental to implementing efficient high-level data parallel operations. The design of the multicast and multireceive primitives is described and an example of a data parallel application utilizing ComPaSS multicast is given. The scalability of these primitives is discussed, and improvements in performance resulting from use of the library on a 64-node nCUBE-2 are presented.