The Cray Research MPP Fortran Programming Model

Abstract

An integral part of any computer system is the programming model because most users program with high level languages. Programming model definition for massively parallel systems is an important research area. In their current Fortran product, Cray Research, Inc. has defined a Fortran based programming model that allows programmers to specify both explicit and implicit communication in a parallel program. The explicit communication is available through a message passing library that supports both a standard interface for sending and receiving data, and low level primitives that directly exploit addressing features available in the target machine, the Cray T3D® system. The implicit communication is available through language features called data sharing and work sharing. The data sharing and work sharing features are available through a set of directives that can be added to existing programs. There is also implied work sharing available through the use of array syntax statements involving shared data. There are other directives and intrinsic functions that provide access to explicit synchronization. One unique quality of this model is that both implicit and explicit communication styles can be combined within the same program.