UIOSLIC parameter

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User I/O slice


Default value
Parameter type
Where set
On user's parameter line by system manager
Related products
Model 204 V7.1


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 UIOSLIC milliseconds pass without the request voluntarily yielding the CPU. After UIOSLIC milliseconds, the user is considered CPU-bound. From this point, if UCPUSLIC 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 Model 204 dynamic dispatching, see Dynamic dispatching.