Background and observations W, L, Waand la are not affected as long as the queue discipline does not give priority to certain classes of customers WEIFOWSIRO= WLIFo (What about the corresponding variances?) Things may change, however, in systems where customers are assigned to various priority classes, if different classes have different service-time characteristics Preemptive VS non-preemptive priority systems Preemptive-resume Vs. preemptive-repeatBackground and observations • W, L, Wq and Lq are not affected as long as the queue discipline does not give priority to certain classes of customers • WFIFO = WSIRO = WLIFO (what about the corresponding variances?) • Things may change, however, in systems where customers are assigned to various priority classes, if different classes have different service-time characteristics • Preemptive vs. non-preemptive priority systems • Preemptive-resume vs. preemptive-repeat