Dynamic Resource Management Scheme for TCP Connections at Internet Servers

Many research efforts have been directed towards avoiding or dissolving the network congestion,which is caused by an increase in network traffic. However, there has been little recent discussion on improvement of the performance of Internet endhosts in spite of the projection that the bottleneck is now being shifted from the network to Internet endhosts. In this thesis, we present a novel scheme of resource management for Internet servers to provide high performance and fair service for many TCP connections at the Internet servers. We first present a new architecture of fair socket buffer management for Web servers, which is called Scalable Socket Buffer Tuning (SSBT), having two major features. The one is the equationbased automatic TCP buffer tuning (E-ATBT) method for Web servers, where the sender host estimates ‘expected’ throughput of the TCP connections through a simple mathematical equation, and assigns the send socket buffer to them according to the estimated throughput. We also introduce the simple memory-copy reduction (SMR) scheme to reduce the number of memory access operations at a TCP sender host by using some of new system calls. The second contribution of this thesis is to propose a new resource/connection management scheme for Web proxy servers to improve their performance and reduce the elapsed Web document transfer time when using Web proxy servers. Our proposed scheme has the following two features: One is an enhanced E-ATBT, which is an enhancement of our E-ATBT proposed for Web proxy servers, in order to effectively handle the dependency of upward and downward TCP connections 1 and to dynamically assign the receive socket buffer. The other is a connection management scheme that prevents newly arriving TCP connection requests from being rejected at the Web proxy server due to a lack of resources. The scheme involves the management of persistent TCP connections provided by HTTP/1.1, which intentionally tries to close them when the resources at the Web proxy server are shorthanded. We evaluate an effectiveness of our proposed schemes through simulation and implementation experiments. From both results, we confirm that our SSBT can achieve up to 30% gain of the Web server throughput, and the fair and effective usage of the sender socket buffer can be achieved. Furthermore, we show our proposed connection management scheme can improve the Web proxy server performance up to 70%, and reduce the document transfer time for Web client hosts.