Multitasking and resequencing in a two-stage multiprocessing system

The effects of multitasking and resequencing on system and program performance of a two-stage multiprocessing system are studied using simulation techniques. A closed queueing network model is considered. It consists of the CPU and the I/O channel. The CPU consists of a FCFS single-server sequential processing center and a multiprocessing center with two FCFS independent processors each serving its own queue. Resequencing of jobs after CPU service ensures that jobs leave the CPU on a first-in first-out basis. We examine how the synchronisation of tasks in the multiprocessing center in conjunction with the subsequent resequencing of jobs affects the overall performance for various coefficients of variation of the CPU service times (exponential and Branching Erlang distributions) and for different degrees of multiprogramming.