ON WRITING A ROUTER FOR MESSAGE-PASSING IN A TRANSPUTER NETWORK

In a distributed memory MIMD parallel machine, the efficient communica tion between processes/processors, through messages, is an important t ask to be handled by the programmer. Because the number of inter-proce ssor connections is limited, the communication between any two process ors is made by passing the messages through several other processors a nd then, a problem of messages routing appears. For dedicated systems, special architectures can be defined simplifying the problem but, if an environment constituting a basis for general applications developme nt is desired, the problem is more serious due to the deadlock possibi lity. A general router, able to avoid the problem, becomes then a very important tool for software development in parallel architectures. We have been defining a development platform, based on a network of Tran sputers and written in OCCAM, for image synthesis applications. This p aper reports our efforts in writing different versions of routers, bas ed on two different strategies, and justifies the choice of an efficie nt one to integrate in the platform.