Dynamic buffer tuning: an ambience-intelligent way for digital ecosystem success

Ambient intelligence is an important element for the success of digital ecosystems which usually are made up of many collaborating distributed nodes. The operations of these nodes affect one another as chain reactions. When one node had failed, it could bring down the whole ecosystem. Dynamic buffer tuning is an ambience-intelligent mechanism because it has the ability to sense the ambient changes and then makes necessary proactive changes on the fly to avoid buffer overflow. As a result the end-to-end communication channel is more dependable, leading to shorter response time and happier clients. Therefore, dynamic buffer tuning should be generally beneficial to digital ecosystem system performance. In this paper we demonstrate this point by using the FLC (Fuzzy Logic Controller) dynamic buffer tuner to quicken the pervasive medical consultation response of the TCM (Traditional Chinese Medicine) Pervasive Digital HealthCare System as an example

TCP Connection Management Mechanisms for Improving Internet Server Performance

This thesis investigates TCP connection management mechanisms in order to understand the behaviour and improve the performance of Internet servers during overload conditions such as flash crowds. We study several alternatives for implementing TCP connection establishment, reviewing approaches taken by existing TCP stacks as well as proposing new mechanisms to improve server throughput and reduce client response times under overload. We implement some of these connection establishment mechanisms in the Linux TCP stack and evaluate their performance in a variety of environments. We also evaluate the cost of supporting half-closed connections at the server and assess the impact of an abortive release of connections by clients on the throughput of an overloaded server. Our evaluation demonstrates that connection establishment mechanisms that eliminate the TCP-level retransmission of connection attempts by clients increase server throughput by up to 40% and reduce client response times by two orders of magnitude. Connection termination mechanisms that preclude support for half-closed connections additionally improve server throughput by up to 18%