A Scalable Run-Time System for NestStep on Cluster Supercomputers

NestStep is a collection of parallel extensions to existing programming languages. These extensions supports a shared memory model and nested parallelism. NestStep is based the Bulk-Synchronous Programming model. Most of the communication of data in NestStep takes place in a combine/commit phase, which is essentially a reduction followed by a broadcast. The primary aim of the project that this thesis is based on was to develop a runtime system for NestStep-C, the extensions for the C programming language. The secondary aim was to find which tree structure among a selected few is the best for communicating data in the combine/commit phase. This thesis includes information about NestStep, how to interface with the NestStep runtime system, some example applications and benchmarks for determining the best tree structure. A binomial tree structure and trees similar to it was empirically found to yield the best performance