MPI (Message Passing Interface) is a specification for a standard library for message passing that was defined by the MPI Forum, a broadly based group of parallel computer vendors, library writers, and applications specialists. Multiple implementations of MPI have been developed. In this paper, we describe MPICH, unique among existing implementations in its design goal of combining portability with high performance. We document its portability and performance and describe the architecture by which these features are simultaneously achieved. We also discuss the set of tools that accompany the free distribution of MPICH, which constitute the beginnings of a portable parallel programming environment. A project of this scope inevitably imparts lessons about parallel computing, the specification being followed, the current hardware and software environment for parallel computing, and project management; we describe those we have learned. Finally, we discuss future developments for MPICH, including those necessary to accommodate extensions to the MPI Standard now being contemplated by the MPI Forum. 1

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...

MPI is the de facto message passing standard for multicomputers and networks of workstations, established by the MPI Forum, a group of universities, research centers, and national laboratories (from both the United States and Europe), as well as multinational vendors in the area of high performance computing. MPI has been implemented already by several groups. Worldwide acceptance of MPI has been quite rapid. This paper overviews several areas in which MPI can be extended, discusses the merits of making such extensions, and begins to demonstrate how some of these extensions can be made. In some areas, such as intercommunicator extensions, significant progress has been made by us already. In other areas (such as remote memory access), we are merely proposing extensions to MPI that we have not yet reduced to practice. Furthermore, we point out that other researchers are evidently working in parallel with us on their own extension concepts for MPI. 1 Introduction The MPI Forum introduced...

Parallel software packages which may be of use in scientific and engineering applications of the type carried out on the parallel computing facilities at EPCC and Daresbury Laboratory are surveyed. For each package, a brief description is given along with other useful information such as availability, contact addresses and systems supported. keywords: parallel computing, software packages, scientific applications. This report is available from http://www.dl.ac.uk/TCSC/HPCI/ c fl1996, Daresbury Laboratory. We do not accept any responsibility for loss or damage arising from the use of information contained in any of our reports or in any communication about our tests or investigations. ii CONTENTS iii Contents 1 Introduction 1 1.1 Criteria for inclusion : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 1 1.2 Package areas : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 1 1.3 Individual entries : : : : : : : : : : : : : : : : : : : : : : : : : : : : : :...