Computer System Performance Measurement : Instruction Set

Techniques based on hardware monitoring were developed to measure computer system performance on the instruction set processor level and the microcode level. Knowledge of system behavior and system utilization at these two levels is extremely valuable for design of new processors. The reasons why such information is needed are discussed and applicable measurement techniques for obtaining necessary data are reviewed. A hardware monitor is a preferable measurement tool since it can trace most of the significant events attributed to these two levels without introducing any artifact. Described hardware monitoring techniques were implemented on the S/370 Model 145 at Stanford University. Measurements performed on the instruction set processor level were concerned with determining execution frequencies on individual instructions under normal system workload. The microcode level measurements measured the number and the type of S/370 Model 145 microwords executed in the process of interpretation of an individual S/370 instruction and the average execution time of each such instruction. Implementation of each technique is described and the results based on the outcome of performed measurements are presented. Finally, effectiveness and ease of use of the discussed techniques are considered.