NonStop Systems Introduction

The NonStop Kernel
NonStop Systems Introduction—527825-001
6-7
Distribution of Control
one processor might need to communicate with a workstation attached to another
processor and with a disk drive controlled by a disk process in yet another processor.
Figure 6-4 on page 6-7 illustrates the requirements of the situation. The user process
in Processor 1 needs to communicate with a terminal process in Processor 2 and a
disk process in Processor 0. How is this interprocess communication across processor
boundaries to be accomplished?
To resolve the problem, the original designers decided that the operating system
should be a message-based system. With such a system, one process could request
the services of other processes (such as I/O processes) anywhere in the system.
Figure 6-4. Multiple Processes in Multiple Processors
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User
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Terminal
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Processor 2
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