MPI is the new standard which defines a set of message passing operations for multicomputers and clustered systems. In comparison to other popular message passing systems, MPI provides a richer collection of functions, allowing efficient implementations, portability and excellent support for the development of parallel libraries. In this paper, we describe the implementation and performance of MPI on the Fujitsu AP1000 multicomputer. To produce an efficient implementation, the operating system on the AP1000 had to be modified to better support MPI. These modifications are presented, along with the hardware operations that were utilised. A selective broadcast operation was developed from the modifications which allowed very efficient group-wide broadcast. The performance of the implementation in comparison to native AP1000 calls is presented with benchmarks of the collective routines implemented using the selective broadcast operation. 1 The MPI Standard The message passing paradigm h...

The diverse message passing interfaces provided on parallel and distributed computing systems have caused difficulty in movement of application software from one system to another and have inhibited the commercial development of tools and libraries for these systems. The Message Passing Interface (MPI) Forum has developed a de facto interface standard which was finalised in Q1 of 1994. Major parallel system vendors and software developers were involved in the definition process, and the first implementations of MPI are already appearing. This article presents an overview of the MPI initiative and the standard interface, in particular those aspects which merge demonstrated research with common practice. 1 Introduction The message passing paradigm is the most generally applicable and efficient programming model for parallel machines with distributed memory and has been used widely in parallel and distributed computing systems for some years. The development of parallel computing has bee...

Parallel programs are typically written in an explicitly parallel fashion using either message passing or shared memory primitives. Message passing is attractive for performance and portability since shared memory machines can efficiently execute message passing programs, however message passing machines cannot in general effectively execute shared memory programs. In order to write a parallel program using message passing, the programmer is often obliged to develop a significant amount of code which manages distributed data and events and parallel input/output, and such code may have little or nothing to do with the application. However many parallel applications have common structural elements and much of this additional code can be encapsulated within a parallel library and reused in several programs. We discuss the requirements the library writer and user makes of the basic message passing interface and describe how we have addressed these requirements in our Common High-Level Inte...

The message passing interface standard released in April 1994 by the MPI Forum [2], defines a set of message passing primitives for multicomputers and clustered systems. The standard provides a large collection of functions, with the aim of providing efficient implementations, source code portability and support for the development of parallel libraries. In this paper, we describe the implementation and performance of MPI on the Fujitsu AP1000. To produce an efficient implementation, the existing operating system had to be modified to better support MPI operations. These modifications are discussed, along with the hardware operations that were utilised. A selective broadcast operation was developed which provided efficient implementations of many of the collective routines regardless of group size. The performance of MPI and CellOS point-to-point and broadcast operations are compared, along with benchmarks of some of the MPI collective routines. More details of the implementation may...

The lack of a portable programming interface for parallel computers has inhibited the development of applications for such systems, and thus restricted the exploitation of this technology. In this paper we discuss various efforts to provide a portable interface to parallel computers, and present the Edinburgh CHIMP (Common High-level Interface to Message-Passing), and PUL (Parallel Utilities Library) activities in this context. The concepts behind these projects are described, with details of the range of parallel systems on which they are available.