Attaining soft real-time constraint and energy-efficiency in web servers
Raphael Pereira de Oliveira Guerra, Julius C. B. Leite, Gerhard Fohler · 2008
M/M/1 queues have been traditionally used to model several systems like phone calls at a call center, banking services and so on. However, recent studies showed that it does not model properly a web server system. In this paper we investigate the impact of this assumption in providing timeliness constraint in an energy-efficient web server. Although energy efficiency is a key issue, it should not be attained at the expense of a poor quality of service. The work proposed here describes a technique that uses queueing theory results to balance energy consumption and adequate application response times in heterogeneous CPU-intensive server clusters. Moreover, we investigate the I/O impact on a purely CPU-oriented energy saving strategy. This proposal shows that the assumption of a Poisson process is a good approximation to model a web server.