Parallel Programming with CHARM :

This Paper describes the research centered on the Charm Parallel Programming System. Charm is a portable parallel programming system under development at the University of Illinois for the past six years. The system enhances latency tolerance via message driven execution, supports dynamic load balancing for medium grain tasks, and provides innovative language features such as speciically shared variables and \branch ooce" processes. The paper describes the philosophy behind the system, and elaborates on its features and their motivation. Completed and ongoing related projects are summarized, including: Dagger, a textual notation and a corresponding visual language for simplifying expression of split-phase communication that is necessary in message driven execution; A subset of the High Performance Fortran that demonstrates superior latency tolerance; Performance feedback and debugging tools that exploit the speciicity of information available to the runtime system to give the user a highly reened and usable feedback; strategies for parallel execution of speculatively parallel computations; and a summary of preliminary applications.