The Parallel Processing Compute Server (PPCS) is a distributed-memory multiprocessing system consisting of System/370™ microprocessors (33 at present) interconnected through a matrix switch. This paper describes the hardware configuration, the extensions to the System/370 instruction set that are provided to support the distributed memory and interprocessor signaling, the modifications to the VIUI/SP operating system that allow it to run effectively on many closely coupled processors (most of which have no disks), and the application-support layer, which permits FORTRAN programs to take advantage of the highly parallel environment. Development of the PPCS is a joint effort of the IBIVI Boblingen Development Laboratory and the IBM Thomas J. Watson Research Center. A prototype PPCS has been installed at CERN.
IntroductionThe Parallel Processing Compute Server (PPCS) is a distributed-memory multiprocessor that uses message passing for interprocessor communication. It comprises an IBM Enterprise System/9373 (ES/9373) Model 30' [1] 1 The ES/9373 Model 30 is an entry-level processor of the Enterprise System/QSTO™ (ES/9370™), which is a family of mM System/370™ processors that support many users and applications in the commercial, engineering, scientific, and industrial environments. integrated host (I-host) system and 32 (at present) System/370 satellite processors [2], all interconnected via a matrix switch designed to accommodate 62 ports. The I-host is the only processor with I/O capability; otherwise, the satellite processors are functionally identical to the I-host processor. Running under the control of Parallel VM, a modified form of the IBM Virtual Machine/System Product (VM/SP) operating system [3], the PPCS is suitable for a variety of numerically intensive computing programs.Parallel VM features "diskless" operation on the satellite processors (but is designed to exploit I/0-capable satellite processors, if they exist), fast interprocessor communications, local and remote inter-virtual-machine message-passing, and, to a large degree, a single-system image as seen by the application programmer.Distributed VS FORTRAN, a prototype programming environment for PPCS, has been developed. VS FORTRAN [4] application programs must be reorganized by the user to exploit parallel processing by originating, scheduling, and synchronizing subtasks. A subroutine library for task management and data transfer has been developed in the spirit of IBM Parallel FORTRAN [5]. The implementation of this Distributed VS FORTRAN library is based on a CMS [3] extension, called CS/X, that takes advantage of the Parallel VM functions.A PPCS with 32 satellite processors. Parallel VM, and CS/X has been installed at the European Organization for Nuclear Research (CERN) and is running applications used by the high-energy physics (HEP) community. At CERN, ®Copyright 1991 by International Business Machines Corporation. Copying in printed form for private use is permitted without payment of royalty provided that (1) each reproduction is done w...