Adaptive global power optimization for Web servers

This work investigates power and performance trade-offs for Web servers on a state-of-the-art, high-density, power-efficient SeaMicro SM15k cluster by AMD. We relied on the concept of virtual power states (VPSs), a combination of CPU utilization rate to the P/C power states available in modern processors, and on our global optimization algorithm called Slack Recovery, to deploy an adaptive global power management system in a production environment. The main contributions of this paper are twofold. First, it presents the Slack Recovery algorithm deployed on a real cluster, composed of 25 SeaMicro nodes. The algorithm finds a P-state and a utilization rate for each CPU node to minimize power under a minimum performance requirement. Second, it proposes a novel mechanism to control utilization rates in each server, a key aspect on our power/performance optimization system which enables the implementation of the VPS concept in practice. Experimental results show that our Slack Recovery-based system can reduce up to 6.7 % of the power consumption when compared to policies usually deployed in SeaMicro production systems.