PowerPC/sup TM/ performance monitor evolution

The evolution of performance monitoring (PM) from its roots in Power/sup TM/ architecture to its current state are explored. Further discussed are many of the PM features in the PowerPC 604e, and the differences between the PMs in some PowerPC processors. To hide some of these differences, an Application Programming Interface (API) was developed. The authors conclude with some of their observations about issues related to the availability of the PM to end users.