Live Webcast 15th Annual Charm++ Workshop

The new generation of parallel applications are complex, involve simulation of dynamically varying systems, and use adaptive techniques such as multiple timestepping and adaptive refinements. Typical implementations of the MPI do not support the dynamic nature of these applications well. As a result, programming productivity and parallel efficiency suffer. In this paper, we present Adaptive MPI (AMPI), an adaptive implementation and extension of MPI with migratable threads. AMPI includes a powerful run-time support system that takes advantage of the freedom of mapping virtual MPI processes (VPs) onto processors. With this run-time system, AMPI supports such features as automatic adaptive overlap of communication and computation and automatic load balancing. It can also support other features such as checkpointing without additional user code, and the ability to shrink and expand the set of processors used by a job at runtime. In this paper, we illustrate that AMPI, while still retaining the familiar programming model of MPI, is better suited for such new generation applications, and does not penalize performance of those applications without the dynamic nature.