14.2.3 Process Priorities

Each process has a priority and can either be runnable, blocked or suspended. If there is a runnable process with priority P, then no processes with priority less than P will run. When there are runnable processes with equal priority, they will be scheduled in a round-robin manner.

If a process with priority P is running and a blocked process with priority greater than P becomes runnable, the second process will run when the scheduler is next invoked (either explicity or at the next preemption tick).

To find the priority of a process, use mp:process-priority . This can be changed using mp:change-process-priority .

(mp: change-process-priority proc-1 10)

Another way to specify the priority is to create the process with mp:process-run-function , passing the keyword :priority :

  "SORTER-DOT" '(:priority 10) #'sorter #\.)
  "SORTER-DASH" () #'sorter #\-))

LispWorks User Guide - 21 Jul 2006