An analytic model of CP-67 - VM/370

Abstract

The paper describes an analytic model of CP-67 - VM/370 (1, 2). Each user (virtual machine) on the system is in one of four states (see Figure 1): dormant (“Console”), receiving interactive service (“Q1”), waiting for batch service (“Queue”), or receiving batch service (“Q2”) The users receiving batch service form the multi-programmed set, and are described by a cyclic queuing network of the Gordon-Newell type (3,4,5). The effect of interactive users is treated by assuming that a fixed portion of system resources is dedicated to them. In order to solve this queuing problem for a given multi-programming level it is necessary to have information on the ratio of channel to CPU busy times. Some of the channel requirements are due to paging, and hence it is necessary to have a characterization of the paging rate vs. memory requirements of various programs.