Universal mechanisms for concurrency

We propose a machine model consisting of a set of primitive mechanisms for communication, synchronization, and naming. These mechanisms have been selected as a compromise between what can easily be implemented in hardware and what is required to support parallel models of computation. Implementations of three models of parallel computation: actors, dataflow, and shared-memory using this model are sketched. The costs of the mechanisms on a particular parallel machine are presented and issues involved in implementing the model are discussed. Identifying a primitive set of mechanisms separates issues of programming models from issues of machine organization. Problems are partitioned into those involving implementation of the primitive mechanisms and those involving implementation of programming models and systems using the mechanisms.