VR-scale: Runtime dynamic phase scaling of processor voltage regulators for improving power efficiency

Hadi Asghari-Moghaddam, Hamid Reza Ghasemi, Abhishek Arvind Sinkar, Indrani Paul, Nam Sung Kim

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


A voltage regulator (VR) for a processor is one of the most critical platform components. Particularly, a VR is required to support fast, accurate, and fine-grained voltage changes for efficient processor power management. Such requirements, nonetheless, can be relaxed when a processor consumes low power at runtime. Thus, manufacturers begin to offer some knobs so that a processor can adapt VR's operating parameters to cost-effectively satisfy the requirements with high efficiency. In this paper, we first demonstrate that: (1) VR efficiency heavily depends on load current (i.e., current delivered to a processor) and a VR operating parameter (e.g., the number of active phases) at given voltage; (2) a processor running a parallel application mostly consumes small current due to aggressive power management; and (3) when the processor is in active state, all the phases are always activated in the VR. (2) and (3) in turn lead to poor VR efficiency at most runtime. Second, we present VR-Scale that dynamically scales the number of active phases based on the predicted load current for the next interval. Our evaluations based on an Intel processor running emerging parallel applications show that VR-Scale can reduce the total power consumed by a processor and its VR by more than 19% with negligible performance impact.

Original languageEnglish (US)
Title of host publicationProceedings of the 53rd Annual Design Automation Conference, DAC 2016
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Electronic)9781450342360
StatePublished - Jun 5 2016
Event53rd Annual ACM IEEE Design Automation Conference, DAC 2016 - Austin, United States
Duration: Jun 5 2016Jun 9 2016

Publication series

NameProceedings - Design Automation Conference
ISSN (Print)0738-100X


Other53rd Annual ACM IEEE Design Automation Conference, DAC 2016
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Computer Science Applications
  • Control and Systems Engineering
  • Electrical and Electronic Engineering
  • Modeling and Simulation


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