Statistical validation methodology of CPU power probes

Abstract

Achieving or proving energy efficiency necessarily relies on the ability to perform power measurements at some point. In order to simplify power measurements at the CPU level, recent processors support model-based energy accounting interfaces such as Intel RAPL or AMD APM. Though such interfaces are an attractive option for energy characterization, their accuracy and reliability has to be verified before using them. We propose a new statistical validation methodology for CPU power estimators that does not require any complex hardware system instrumentation. The methodology only relies on a single full-system AC power meter and is able to make statistically relevant decisions about the probes reliability. We also present an experimental evaluation using two Intel machines equipped with a RAPL interface and investigate the impact of multiple parameters such as the CPU frequency or the number of active cores on the probe accuracy.