Using SADTs to support irregular computational problems

There are well defined methods for supporting regular problems with scalable performance, typified by the HPF language and the BSP model. Less well understood is the solution of more irregular problems, supporting complex shared data structures and task dependencies, and typically requiring dynamic load balancing to sustain high performance. It is demonstrated how the use of Shared Abstract Data Types (SADTs), together with an extended BSP cost model, can support irregular problems in a structured manner An SADT is an extension of a serial ADT which allows the concurrent invocation of its methods. A number of SADTs are used to implement a solution of the travelling salesman problem on the Cray T3D machine, and a description of the restructuring of a parallel CFD code using SADTs is provided, with initial results given for the Cray T3E