PORTABLE PROGRAMMING WITH THE PARMACS MESSAGE-PASSING LIBRARY

Message passing is the most efficient and most general programming par adigm currently used on parallel machines with distributed memory. In the absence of a message passing standard the broad variety of vendor- specific interfaces inhibits the portability of application programs. The PARMACS library which is presented in this paper defines a portabi lity layer which has been implemented on most MIMD computers, ranging from MPP systems to workstation networks. The new release version 6.0 is discussed in detail. It is available for applications written in Fo rtran 77 and C. To assess the time overhead caused by PARMACS, two ben chmark applications with differing communication requirements have bee n implemented using machine-specific interfaces and portably using PAR MACS. The performance has been compared for problems of various sizes on three machines of different architectures. In general the use of PA RMACS does not cause any significant overhead.