Control of queues in a permissive society

Abstract

By attaching anXDS Sigma 2 computer to Atlas via a shared disk, a multi-access facility has been developed without causing any interruption in the day to day running of the Atlas batch processing system. Jobs may be initiated on Atlas from a terminal and results from such jobs may be either returned to files or published on any of the normal Atlas peripherals.A statistics collecting package is included, which allows the gathering of information about any part of the system. Also, modifications can easily be made to the system to test the predictions of such a model. The model described here tries to relate response time to various system loads. In order to allow for the overlapping of disk and CPU time, we have queued the two activities in series.One of the useful side effects of constructing such I model is the focussing of attention on areas of the software which really do affect the response time. The paper outlines the development of this model, which is s t i l l in progress, highlighting some of the milestones and pitfalls encountered so far.KEY WORDS Multi-access Modelling Markov * This paper describes the work undertaken on an extension of a model first used by Scherr at MIT.