VAX 6000 Model 400 performance

The performance of the VAX 6000 Model 400 system, which supports up to six tightly coupled processors under the VAX/VMS symmetric multiprocessing operating system, is presented. The study focuses on the modeling and measurement techniques used to evaluate the performance of the system. The major consideration in this study is to evaluate multiprocessor performance accurately in real application environments. Data captured at several timesharing live user sites were used to develop multiuser workloads. User activities and resource utilizations were accurately replicated in these workloads. Two workloads were used to represent the major market segments-technical and commercial. Modeling and measurement techniques were used to evaluate the performance of the system on the basis of these workloads. Modeling was done using performance simulation techniques to predict microprocessor efficiency across the workloads. Results indicate that the application level multiprocessor performance becomes sensitive to contention for shared resources as the number of processors in the system is increased. This contention for shared resources seems to be higher in the commercial environments than in the engineering scientific environments.<>