A hardware monitor study of a CDC KRONOS system

ABSTRACT

This study was performed on a CDC-6600 computer having 500K of Extended Core Storage (ECS), twenty Peripheral Processor Units (PPU's) and twenty-four I/O channels, as shown in Figure I-1. The CPU can load, store, and execute from the 131K of 1 microsecond storage which comprises CM. It can also access ECS, but this access is limited to transferring blocks of data between CM and ECS at the rate of ten 60-bit words per microsecond. The CPU cannot access peripheral devices in any manner whatever. The KRONOS operating system supports both batch and time-sharing users. As many user programs as will fit in CM may be loaded at any one time, with the CPU time-sliced among them. Swapping (called rollin and rollout under KRONOS) is performed to ECS with overflow to disk. A serious drawback of the CDC supplied system is that ECS rollouts are performed through a PPU and the Distributed Data Path (DDP), which is one hundred times slower than the CM/ECS direct transfer available to the CPU.

INDEX TERMS

Primary Classification:
  D. Software
  D.4 OPERATING SYSTEMS

Additional Classification:
  D. Software
  D.4 OPERATING SYSTEMS
      D.4.8 Performance
          Subjects: Monitors

General Terms:
Measurement