The Application of Optimal Stochastic Control Theory in Computer System Load Regulation

A method using some results and techniques of Optimal Stochastic Control Theory is introduced to compute the optimal admission policy for paged batch-interactive computer systems. The admission policy determines the optimal number of batch and terminal jobs that should be activated at each system state to maximize throughput. The system state is defined as the vector (N1,N2) where N1 and N2 are respectively the total number of terminal and batch jobs in the system. Thus the policy is adaptive to workload variation. As well, the quality of service given to each class of jobs (specifically their mean response times) can be adjusted by choosing a suitable weight for the terminal jobs. A large weight reduces the mean response time of the terminal jobs at the expense of the mean batch response time while maintaining the total system throughput at its maximum level.

Unlike most existing adaptive control algorithms, the approach is based on mathematical modelling and its extension to cover the case of more than two classes of jobs is straightforward.