An E cient Processor Network Interface for Local Area Multiprocessors

Most computing environments today consist of a number of workstations or personal comput ers PCs connected via a high speed in terconnection network These environments are usually called workstation clusters while acronyms like COWs Clusters of Worksta tions and NOWs Networks of Workstations are popular as well Although worksta tion clusters have the aggregate processing memory and I O capacity to execute high performance applications they usually lack the required hardware support that allows them to present a high performance communication in terface to user applications Network interfaces and communication protocols designed for slow and untrusted networks impose a number of overheads in both message passing and shared memory applications resulting in loss of a large amount of bandwidth at the application al though the underlying network may provide signi cant bandwidth The main sources of these overheads include