Empirical Study of the Power Consumption of the x86-64 Instruction Decoder

Mikael Hirki, Zhonghong Ou, Kashif Nizam Khan, Jukka Nurminen, Tapio Niemi

Research output: Chapter in Book/Report/Conference proceedingConference contributionProfessional

Abstract

It has been a common myth that x86-64 processors suffer in terms of energy efficiency because of their complex instruction set. In this paper, we aim to investigate whether this myth holds true, and determine the power consumption of the instruction decoders of an x86-64 processor. To that end, we design a set of microbenchmarks that specifically trigger the instruction decoders by exceeding the capacity of the decoded instruction cache. We measure the power consumption of the processor package using a hardware-level energy metering model called the Running Average Power Limit (RAPL), which is supported in the latest Intel architectures. We leverage linear regression modeling to break down the power consumption of each processor component, including the instruction decoders. Through a comprehensive set of experiments, we demonstrate that the instruction decoders can consume between 3% and 10% of the package power when the capacity of the decoded instruction cache is exceeded. Overall, this is a somewhat limited amount of power compared with the other components in the processor core, e.g., the L2 cache. We hope our finding can shed light on the future optimization of processor architectures.
Original languageEnglish
Title of host publicationUSENIX Workshop on Cool Topics on Sustainable Data Centers (CoolDC 16)
PublisherUSENIX : THE ADVANCED COMPUTING SYSTEMS ASSOCIATION
Number of pages6
Publication statusPublished - 2016
MoE publication typeD3 Professional conference proceedings
EventUSENIX Workshop on Cool Topics in Sustainable Data Centers - Santa Clara, United States
Duration: 19 Mar 201619 Mar 2016

Workshop

WorkshopUSENIX Workshop on Cool Topics in Sustainable Data Centers
Abbreviated titleCoolDC
Country/TerritoryUnited States
CitySanta Clara
Period19/03/201619/03/2016

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