Dynamic Priority Assignment Research Articles

Optimal allocation of a server between two queues with due times

Two queues share a single server. Arrivals to each queue have individual target due times for service completion (their due times are known to the controller) and a penalty is incurred when they stay in the system after the expiration of these due times. The two classes have different service requirements and incur penalty at different rates. The problem of dynamic priority assignment so as to minimize the discounted and average tardiness per customer is considered. The problem is formulated in discrete time where it is shown that, under the assumptions of geometric arrivals and geometric services, there is a nonidling stationary optimal preemptive policy. Within each class, the policy chooses, if at all, the customer with the smallest due time. A partial order on the space of the set of residual times is introduced. It is shown that the optimal choice of the customer class is monotonic with respect to this partial order; this implies a switchover-type property in the appropriate space. A combination of stochastic dominance and dynamic programming ideas is used to establish the results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Improved performance in a local area network integrating voice and data

AbstractThe performances of a Local Area Network (LAN) integrating voice and data are improved changing the 2 register management in the Reserved Virtual Time CSMA protocol adopted for vocal packets, and using a new exponential backoff algorithm for voice, that introduces a maximum backoff time equal to the vocal packet size involved in the retransmission. In addition, a dynamic priority assignment is used between voice and data, that permits to consider a finite number of buffers for data packets.Simulation results are presented to evaluate LAN performances.

A simulation tool for performance evaluation of the IBM 360/75

In this paper we present some results obtained from using simulation as a tool for evaluating alternative methods of improving system performance in network computers. We begin by describing a GPSS model which was developed to evaluate the current computer center operations at the University of Illinois. While using actual data from the center to verify that the model accurately predicts each job's total time in the system, we evaluate the resource utilization within the center. Then we use the simulator to show that a proposed dynamic priority assignment algorithm yields better throughput than the existing algorithm while maintaining a higher level of CPU and memory utilization. Next, turning our attention to a hypothetical network of three centers, we use a generalization of our model to demonstrate the effects of load leveling between centers on the total system throughput. Here we also explore the merits of “pay-for-priority” schemes in both a single center and in a network of three centers.

Dynamic Resolution of Memory Access Conflicts

This note presents a method for designing and implementing a dynamic priority assignment memory-access conflict-resolution circuit for use in multiprocessing systems with K processors. A decision rule which establishes the priority, assignment is given and an example which illustrates the techniques is also discussed.