An autonomic admission control policy for distributed web systems

AbstractThis paper tackles the problem of autonomic ad-mission control for web clusters. The main contribution of this work is the proposal of a new session admission algorithm that self-congures a dynamic constraint on the rate of incoming new sessions to guarantee the respect of Service Level Agreements (SLA). Unlike other approaches, our policy does not need any prior information on the incoming trafc, nor any assumption on the probability distribution of request inter-arrival or service time. Furthermore, it does not require any manual conguration or parameter tuning. We performed extensive simulations under a range of op-erating conditions and compared our algorithm to other pre-viously proposed approaches. The simulations show that our policy rapidly adapts to the given trafc prole and improves service throughput while respecting the response time constraints imposed by the SLAs. It also improves service quality by reducing the oscillations of response time and number of active clients common to other policies. I