A Regression Model of a Swapping System

This paper describes a measurement experiment performed on a PDP 11/45 system running under UNIX (version six) which employs swapping rather than paging in managing memory. Regression equations relating the system's responsiveness to certain system and workload parameters are obtained. Sample applications such as predicting the system's performance due to workload and system changes, load control as well as representing the swapping behaviour in simulation and analytic models are presented. The similarities between the paging and swapping dynamics are discussed. The paper also includes a brief discussion of the accuracy of the model as well as the advantages and disadvantages of the regression technique.