IOSLICE parameter

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CPU slice - IO


Default value
Parameter type
Where set
On User 0's parameter line or reset by system manager
Related products
Model 204 V6.1 or earlier


The CPU time slice allotment, in milliseconds, for non-CPU-bound users

This parameter determines which requests are considered CPU-bound. A user request is considered IO-bound unless IOSLICE milliseconds pass without the request voluntarily yielding the CPU. After IOSLICE milliseconds of CPU have been consumed, the user is considered CPU-bound. From this point, if CPUSLICE milliseconds expire without yielding the CPU, the user is time sliced (forced to yield the CPU to the user with the next highest priority).

A user voluntarily yields the CPU by any of the following actions:

  • Executing a READ SCREEN, READ MENU, or $Read statement
  • Requesting I/O to a Model 204 file or external sequential file
  • Going into a wait for a record or resource lock

Decreasing IOSLICE causes more requests to be considered CPU-bound, and increasing it causes fewer requests to be classed as CPU-bound.

Increasing this parameter diminishes the impact of dynamic dispatching, thus allowing CPU-bound requests to monopolize the CPU. Decreasing this parameter heightens the effect of dynamic dispatching, resulting in increased scheduler overhead.

For more information about CPU access, see dynamic dispatching.