MODELING AND MEASUREMENT OF FAULT-TOLERANT MULTIPROCESSORS.

The workload effects on computer performance are addressed first for a highly reliable unibus multiprocessor used in real-time control. As an approach to studying these effects, a modified Stochastic Petri Net (SPN) is used to describe the synchronous operation of the multiprocessor system. From this model the vital components affecting performance can be determined. However, because of the complexity in solving the modified SPN, a simpler model, i. e. , a closed priority queueing network, is constructed that represents the same critical aspects. The use of this model in evaluating an existing system, the Fault Tolerant Multiprocessor (FTMP) at the NASA AIRLAB, is outlined with some experimental results. Also addressed in the technique of measuring fault latency, an important microscopic system parameter. The authors present a new methodology for indirectly measuring fault latency, and derive the distribution of fault latency from this methodology.