Self-Tuning Batching with DVFS for Improving Performance and Energy Efficiency in Servers

Performance improvement and energy efficiency are two important goals in provisioning Internet services in data center servers. In this paper, we propose and develop a self-tuning request batching mechanism to simultaneously achieve the two correlated goals. The batching mechanism increases the cache hit rate at the front-tier Web server, which provides the opportunity to improve application´s performance and energy efficiency of the server system. The core of the batching mechanism is a novel and practical two-layer control system that adaptively adjusts the batching interval and frequency states of CPUs according to the service level agreement and the workload characteristics. The batching control adopts a self-tuning fuzzy model predictive control approach for application performance improvement. The power control dynamically adjusts the frequency of CPUs with DVFS in response to workload fluctuations for energy efficiency. A coordinator between the two control loops achieves the desired performance and energy efficiency. We implement the mechanism in a test bed and experimental results demonstrate that the new approach significantly improves the application´s performance in terms of the system throughput and average response time. The results also illustrate it can reduce the energy consumption of the server system by 13% at the same time.