ORT - A Communication Library for Orthogonal Processor Groups

Many implementations on message-passing machines can benefit from an exploitation of mixed task and data parallelism. A suitable parallel programming model is a group-SPMD model, which requires a structuring of the processors into subsets and a partition of the program into multi-processor tasks. In this paper, we introduce a library support for the specification of message-passing programs in a group-SPMD style allowing different partitions in a single program. We describe the functionality and the implementation of the library functions and illustrate the library programming style with example programs. The examples show that the runtime on distributed memory machines can be considerably reduced by using the library.