Power capping: a prelude to power shifting

  • Authors:

  • Charles Lefurgy;Xiaorui Wang;Malcolm Ware

  • Affiliations:

  • Austin Research Laboratory, IBM Research Division, Austin, USA 78758;University of Tennessee, Knoxville, USA;Austin Research Laboratory, IBM Research Division, Austin, USA 78758

  • Venue:
  • Cluster Computing
  • Year:
  • 2008

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Abstract

We present a technique that controls the peak power consumption of a high-density server by implementing a feedback controller that uses precise, system-level power measurement to periodically select the highest performance state while keeping the system within a fixed power constraint. A control theoretic methodology is applied to systematically design this control loop with analytic assurances of system stability and controller performance, despite unpredictable workloads and running environments. In a real server we are able to control power over a 1 second period to within 1 W and over an 8 second period to within 0.1 W. Conventional servers respond to power supply constraint situations by using simple open-loop policies to set a safe performance level in order to limit peak power consumption. We show that closed-loop control can provide higher performance under these conditions and implement this technique on an IBM BladeCenter HS20 server. Experimental results demonstrate that closed-loop control provides up to 82% higher application performance compared to open-loop control and up to 17% higher performance compared to a widely used ad-hoc technique.