PRIORITY_OFFSET

   PRIORITY_OFFSET specifies the difference in priority required
   by the scheduler for one process to preempt the current process.
   A value of 2, for example, means that if the current process
   is executing at priority 1, a computable process at priority 2
   or 3 is not allowed to preempt the current process. However, a
   priority 4 or higher process can preempt the current process.
   This mechanism affects only normal priority (0-15) processes. The
   default value is 0.

   This special parameter is use by VSI and is subject to change. Do
   not change this parameter unless VSI recommends that you do so.