Powernightmares: The Challenge of Efficiently Using Sleep States on Multi-core Systems

  • Thomas Ilsche
  • Marcus Hähnel
  • Robert Schöne
  • Mario Bielert
  • Daniel Hackenberg
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10659)


Sleep states are an important and well-understood feature of modern server and desktop CPUs that enable significant power savings during idle and partial load scenarios. Making proper decisions about how to use this feature remains a major challenge for operating systems since it requires a trade-off between potential energy-savings and performance penalties for long and short phases of inactivity, respectively. In this paper we analyze the default behavior of the Linux kernel in this regard and identify weaknesses of certain default assumptions. We derive pathological patterns that trigger these weaknesses and lead to ‘Powernightmares’ during which power-saving sleep states are used insufficiently. Our analysis of a workstation and a large supercomputer reveals that these scenarios are relevant on real-life systems in default configuration. We present a methodology to analyze these effects in detail despite their inherent nature of being hardly observable. Finally, we present a concept to mitigate these problems and reclaim lost power saving opportunities.


Linux Sleep state Energy efficiency Power consumption 



This work is supported in part by the German Research Foundation (DFG) within the CRC 912 - HAEC and by the European Union’s Horizon 2020 program in the READEX project (grant agreement number 671657). The authors thank Thomas Kissinger for the report and initial discussion that led to this investigation.


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Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  • Thomas Ilsche
    • 1
  • Marcus Hähnel
    • 2
  • Robert Schöne
    • 1
  • Mario Bielert
    • 1
  • Daniel Hackenberg
    • 1
  1. 1.Center for Information Services and High Performance Computing (ZIH)Technische Universität DresdenDresdenGermany
  2. 2.Operating Systems GroupTechnische Universität DresdenDresdenGermany

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