The Parallel Processing Compute Server

Abstract

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 signalling, the modification to the VM/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. 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, on-line data acquisition and preprocessing of experimental data is a major computing task. High-energy physics experiments can generate streams of data at a rate of several gigabytes per second. Once filtered and recorded, data are subject to further analysis off-line. Both on-line and off-line processing are numerically intensive computing jobs. The PPCS is primarily intended for the off-line processing, but it can be used for on-line work as well.