LONG
KeSetBasePriorityThread(
  IN  PKTHREAD Thread,
  IN  LONG Increment
  );

Routine Description:

    This function sets the base priority of the specified thread to a
    new value.  The new base priority for the thread is the process base
    priority plus the increment.

Arguments:

    Thread  - Supplies a pointer to a dispatcher object of type thread.

    Increment - Supplies the base priority increment of the subject thread.

        N.B. If the absolute value of the increment is such that saturation
             of the base priority is forced, then subsequent changes to the
             parent process base priority will not change the base priority
             of the thread.

Return Value:

    The previous base priority increment of the specified thread.