On the Apparent Continuity of Processing in a Paging Environment

Abstract

The page-faulting rate is one of the important criteria measuring the performance of a virtual storage under demand paging. In a multiprogrammed and/or time-sharing environment, a job is not expected to be run from the beginning to the end without interruption. In effect, it is segmented into phases and run piecewise. When running in this “segmented mode,” a job phase upon initiation will most likely not possess the storage contents left by its preceding job phase (from the same job). Further, a job running in a paging environment at time t has a nonzero probability of referencing information brought to the high-speed store before t. Hence, for a given job, the segmented mode will yield a higher page faulting rate than the “continuous mode” in which the job runs continuously from the beginning to the end. By saving and retrieving its “working ensemble” upon the termination and initiation of a job phase, a job can be made to possess an “apparent continuity” insofar as the storage activity is concerned. The performance of the “apparently continuous” mode is hoped to approximate that of the continuous mode with an insignificant amount of overhead. Based on this observation, a storage organization oriented toward the minimization of overhead, is proposed. Simulation has been done for verification. Copyright © 1970 by The Institute of Electrical and Electronics Engineers, Inc.