Runtime coupling of data-parallel programs

We consider the problem of efficiently coupling multiple data-parallel programs at runtime. We propose an approach that establishes mappings between data structures in different data-parallel programs and implements a user-specified consistency model. Mappings are established at runtime and can be added and deleted while the programs being coupled are in execution. Mappings, or the identity of the processors involved, do not have to be known at compile-time or even link-time. Programs can be made to interact with different granularities of interaction without requiring any re-coding. A-priori knowledge of consistency requirements allows buffering of data as well as concurrent execution of the coupled applications. Efficient data movement is achieved by pre-computing an optimized schedule. We describe our prototype implementation and evaluate its performance using a set of synthetic benchmarks. We examine the variation of performance with variation in the consistency requirement. We demonstrate that the cost of the flexibility provided by our coupling scheme is not prohibitive when compared with a monolithic program that performs the same computation.