Just came across this good AIX wiki article about monitoring the POWER7 CPU/core frequency changing on the fly and the new lparstat command options ( -Ew). This allows you to see what is happening with your GHz (like pmcycles -M but collected regularly).
- This article is written by a guru in the AIX Performance Tools developers group.
It explains how the utilisation numbers are adjusted to allow for GHz using the PURR and SPURR hardware counters built in the processor to get accurate CPU stats.
Check it out here - CPU Frequency Monitoring using lparstat