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

Report
Authors:Lu, Chenyang, Department of Computer ScienceUniversity of Virginia Abdelzaher, Tarek, Department of Computer ScienceUniversity of Virginia Stankovic, John, Department of Computer ScienceUniversity of Virginia Son, Sang, Department of Computer ScienceUniversity of Virginia
Abstract:

This paper presents the design and implementation of an adaptive architecture to provide relative, absolute and hybrid service delay guarantees for different service classes on web servers under HTTP 1.1. The first contribution of this paper is the architecture based on feedback control loops that enforce delay guarantees for classes via dynamic connection scheduling and process reallocation. The second contribution is our use of feedback control theory to design the feedback loop with proven performance guarantees. In contrast with ad hoc approaches that often rely on laborious tuning and design iterations, our control theory approach enables us to systematically design 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 our adaptive server provides robust delay guarantees even when workload varies significantly. Properties of our adaptive web server also include guaranteed stability, and satisfactory efficiency and accuracy in achieving desired delay or delay differentiation.

Rights:
All rights reserved (no additional license for public reuse)
Language:
English
Source Citation:

Lu, Chenyang, Tarek Abdelzaher, John Stankovic, and Sang Son. "A Feedback Control Architecture and Design Methodology for Service Delay Guarantees in Web Servers." University of Virginia Dept. of Computer Science Tech Report (2001).

Publisher:
University of Virginia, Department of Computer Science
Published Date:
2001