Performance modeling and measurements of real time multiprocessors with time-shared buses

Abstract

A closed queueing network model is constructed to address workload effects on computer performance for a highly reliable unibus multiprocessor used in real-time control. The model consists of multiserver nodes and a nonpreemptive priority queue. Use of this model requires partitioning the workload into task classes. The time-average steady-state solution of the queuing model directly produces useful results that are necessary in performance evaluation. The model was experimentally justified with the fault-tolerant multiprocessor located at the NASA AIRLAB. Extensive experiments were performed using a synthetic workload generator to measure directly performance parameters, such as processor idle time, system bus contention and task processing times. These measurements determine values for parameters in the queueing model. Experimental and analytic results are compared, demonstrating the validity of the model. >