On the accuracy and usefulness of analytic energy models for contemporary multicore processors

TL;DR

This paper refines performance and power models for multicore processors, enabling accurate predictions of performance and energy consumption, and provides insights into optimizing energy efficiency across different processor architectures.

Contribution

It introduces improved models for performance and power that accurately predict energy and performance metrics on modern multicore CPUs, validated on multiple architectures.

Findings

Models accurately predict performance and energy consumption.

Statistical analysis reveals chip quality variations.

Models identify optimal operating points for energy efficiency.

Abstract

This paper presents refinements to the execution-cache-memory performance model and a previously published power model for multicore processors. The combination of both enables a very accurate prediction of performance and energy consumption of contemporary multicore processors as a function of relevant parameters such as number of active cores as well as core and Uncore frequencies. Model validation is performed on the Sandy Bridge-EP and Broadwell-EP microarchitectures. Production-related variations in chip quality are demonstrated through a statistical analysis of the fit parameters obtained on one hundred Broadwell-EP CPUs of the same model. Insights from the models are used to explain the performance- and energy-related behavior of the processors for scalable as well as saturating (i.e., memory-bound) codes. In the process we demonstrate the models' capability to identify optimal operating points with respect to highest performance, lowest energy-to-solution, and lowest energy-delay product and identify a set of best practices for energy-efficient execution.