A model of performance for virtual memory systems

摘要: Queueing network models are well suited for analyzing certain resource allocation problems associated with operating system design. An example of such a problem is the selection level multiprogramming in virtual memory systems. If number programs actively competing main allowed to reach too high value, trashing will occur and performance be seriously degraded. On other hand, may also suffer if drops low since resources can become under utilized this case. Thus it important systems maintain optimal or near levels at all times.This paper presents an analytic model computer behavior which used study optimization The model, explicitly represents numerous interactions as varies, numerically generate curves representative sets parameters. A simplified consisting CPU single backing store device then derive approximate expression multiprogramming. examine transient systems.The mathematical we present based on some simplifying assumptions; particular executing supposed statistically identical. In respect must considered theoretical explanation phenomenon (thrashing) observed rather than exact representation reality. Certain assumptions relaxed simulation where distribution functions service times secondary input-output devices arbitrary; by comparison results see that utilization throughput not very sensitive specific forms these distributions usual exponential yield quite satisfactory results. programmed contain overhead. Again observe model's predictions fair agreement useful predicted experiments.