(4) OS for Parallel Inference Machines: PIMOS

	Machine:     PIM, Multi-PSI
	Environment: SIMPOS
	Language:    KL1
	Source Code: 5.5 MB
	Documents:   Japanese manuals,
	             Introductory manual in English

Overview

The operating system used commonly on all models of PIM.

Characteristics

With large-scale parallel computer systems, the centralized management policy conventionally taken will make management the bottleneck of the whole sytem. PIMOS employs a hierarchical and distributed management policy to avoid the bottleneck. Actually, even on PIMs with their largest configuration currently available (with 256 processors), management does not at all makes a bottleneck. PIMOS is thoroughly written in KL1, a concurrent logic language, and its superior portability has been proved on its porting to different models of PIM.

Function

For coherency with fine-grain parallel programs in KL1, the user interface is based on data-flow synchronization, which is one of the basic features of KL1.

PIMOS, of course, features I/O resource management functions that virtualize and multiplex physical I/O devices. PIMOS, in addition, virtualizes resources required for software development, such as executable program codes, in a coherent manner. All the virtualized resources are managed under the server-client model, keeping the kernel of the operating system smaller and allowing easier extension of the system by simply adding servers.

In addition to its conventional "telnet" remote login feature, a specialized remote access feature from PSI sequential inference workstations is provided, allowing effectively combining features PSI with those of the parallel inference machines.

Software development support tools (compiler with powerful macro and preprocessing functions, low overhead debugging tracer for compiled codes, graphical visualizer of execution profile such as load distribution, etc) provide a comfortable software development environment for KL1. For still easier software development, basic software building blocks are provided such as utilities for data storage, search and update, or libraries for semi-automatic dynamic load distribution.

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