Issue No. 02 - March (1980 vol. 6)
P.S. Kritzinger , Department of Computer Science, University of Stellenbosch
A queuing analysis of a preemptive, priority-driven, time-sliced dispatcher algorithm, typical of those found in many time-sharing systems, is presented. A distinctive feature of the system being modeled is that a preempted task, when readmitted to the dispatcher, is reallocated a full time slice rather than the residual. The combination of preemption, time-slice renewal and class-dependent arrival and service rates places the analysis beyond that of the well-known FBN algorithms. The model is used to predict the behavior of the dispatcher algorithm under various workloads. The model reveals that, at high arrival rates, the time-slice renewal policy prevents processor bound tasks from being relegated to the lower priority queues, thereby severely degrading the throughput of tasks with short processor requirements.
time slicing, Computer performance modeling, dispatcher algorithms, multilevel feedback queue, priority preemption
P.S. Kritzinger, A.E. Krzesinski, P. Teunissen, "A Queuing Model of a Time-Sliced Priority-Driven Task Dispatching Algorithm", IEEE Transactions on Software Engineering, vol. 6, no. , pp. 219-225, March 1980, doi:10.1109/TSE.1980.230472