Power-performance management on an IBM POWER7 server

The processor and cooling subsystems of high-performance servers consume a significant portion of total system power. In this paper, we use the server energy-efficiency benchmark SPECpower ssj2008 to assess dynamic power management strategies for these sub-systems on an IBM POWER 750 platform. First, we evaluate the impact of feedback-driven fan control to reduce power while continuously maintaining a suitable thermal environment. Next, we demonstrate the importance of refining traditional utilization-based DVFS algorithms when managing systems with large core and thread counts. We present a new approach and demonstrate its effectiveness with real-world scenarios for dynamic power management. With reliable runtime power management, we can safely boost (turbo) core frequencies beyond their nominal values to achieve higher throughput. The combined effect of dynamic fan and enhanced processor DVFS control yields an overall improvement of 43% for the energy-efficiency score of the SPECpower ssj2008 benchmark on our test system.