Defining and querying threshold values for I/O priority classes

IOPT_PRI_HIGH and IOPT_PRI_MED define the threshold values for the tasks with high, medium and low priority. Here the I/O priority of a task is derived from its task priority. The threshold values that are currently valid can be queried.

IOPT_PRI                                                                                                                                                 

IOPT_PRI_HIGH=x

IOPT_PRI_MED=y

IOPT_PRI_HIGH?

IOPT_PRI_MED?

x	Threshold value for the I/O priority HIGH. All tasks with a task priority which is less than or equal to x belong to the class HIGH (prio <= x). Value range: 0 <= x <= 255 Default value: 155
y	Threshold value for the I/O priorities MEDIUM and LOW. All tasks with a task priority which is greater than x and less than or equal to y belong to the class MEDIUM (x < prio <= y). All tasks with a priority which is greater than y belong to the class LOW (y < prio). Value range: x < y <= 255 Default value: 205
?	The threshold values for the classes HIGH and MEDIUM are queried.

The threshold values are effective only if the IO-PRIORITY operand in /MODIFY-TASK-CATEGORIES has the value *NONE. However, you are recommended to define the I/O priorities using /MODIFY-TASK-CATEGORIES because the I/O priority can then be assigned independently of the task priority. You may also want two tasks with the same task priority to have different I/O priorities because they differ in their I/O intensiveness.