Round robin scheduling in a computer communications system with finite swap time and statistically multiplexed arrivals

Abstract

A study is made of the effect of asynchronous time division multiplexing (ATDM) on the performance of a computer-communications system. The study is based partly on analysis and partly on a simulation of a system model composed of the following subcomponents: 1. an M/D/1 queue for the ATDM, and 2. a “round robin” processor with finite (nonzero) “swap time” for the computer. The study is an extension of previous work on the subject which assumed a less general model for the computer and was mostly concerned with the conditions for significant distortion of the arrival process at the computer and an observable change in average total delay for a typical Job. The results include a comparison of the delays encountered by a user request in the system as a whole and in the system subcomponents with and without ATDM. Further, there is a discussion of the effects of varying the parameters of the subsystems on the performance of both the computer subsystem and the computer-communications system as a whole. Finally, there is a warning that in a system with ATDM, under certain conditions, the time-sharing system becomes, effectively, a batch processing system.