Power use at partial utilization with SPECjbb 2005
Before we close out our look at power efficiency, I'd like to consider another example. I've measured power use in SPECjbb2005 in order to show how it scales with incremental increases in load. I've only used a single instance of the JVM so that we can see a nice, gradual step up in load—two instances would take us to peak utilization much quicker.

We've graphed the quad-core Opterons and Xeons together. Since the dual-core Opterons take much longer to finish, they get their own graph.

Well, that's interesting to see. I'm not sure exactly what to make of it just yet. I'd like to correlate power and performance here, but as I've mentioned, our testing time has been limited. Perhaps next time.