Feedback Control Architecture and Design Methodology for Service Delay Guarantees in Web Servers

Chenyang Lu, Ying Lu, T.F. Abdelzaher, J.A. Stankovic, Sang Hyuk Son
2006 IEEE Transactions on Parallel and Distributed Systems  
This paper presents the design and implementation of an adaptive Web server architecture to provide relative, absolute and hybrid connection delay guarantees for different service classes. The first contribution of this paper is the architecture based on feedback control loops that enforce desired connection delays via dynamic connection scheduling and process reallocation. The second contribution is the use of control theoretic techniques to model and design the feedback loops with proven
more » ... rmance guarantees. In contrast with heuristics-based approaches that rely on laborious hand-tuning and testing iteration, the control theoretic approach enables systematic design of an adaptive Web server with established analytical methods. The design methodology includes using system identification to establish dynamic models for a Web server, and using the Root Locus method to design feedback controllers to satisfy performance specifications. The adaptive architecture has been implemented by modifying an Apache Web server. Experimental results demonstrate that the adaptive server provides robust delay guarantees even when workload varies significantly. Properties of the adaptive Web server also include guaranteed stability, and efficient convergence to desired performance set points in response to significant fluctuation in user populations.
doi:10.1109/tpds.2006.123 fatcat:ynuqh7iamfesfkzo66dyqsisd4