Web Performance Measurement

• Project Description
• Project Activities
• Project Members
• Publications
  

Project Description

This project consists of a series of measurement-based studies of Web performance. Our ongoing activities include:

• evaluating the performance implications of different content serving architectures
• identifying and quantifying network factors that affect Web response time
• building tools to aid in Web performance measurement
• identifying the cause and location of network performance problems at hosting centers

These activities are described further below.

Project Activities

Content Serving Alternatives

We have studied the impact of several alternative Web serving architectures on client-perceived response time

• single server location -- the traditional approach of placing content in a single data center that uses a single network provider (perhaps dual-homed with a secondary provider providing backup service).

• single server location with multiple ISPs -- in this approach the data center provides direct connectivity to multiple ISPs to improve performance and availability, usually with additional control over BGP routing to influence the ISP used to send packets to and from different clients.

• multiple server locations -- content is placed in few regional data centers to improve availability and performance for some clients

• widely distributed servers -- content is served from a content distribution network which has a large distributed set of small servers spread across many service providers

Network Factors and Web Response Time

End-to-end Web performance is influenced by a large number of factors including Web server platform, protocol features, and network characteristics. In contrast to earlier work that primarily studied the impact of Web servers or the HTTP protocol on Web performance, this project examines network-related factors. In particular, we focus on the impact of network path characteristics and network connectivity of both clients and servers on Web response time. Our findings are based on two sets of measurements from diversely connected measurement agents to two identical servers placed in commercial hosting locations.

Web Performance Measurement Tools

We have developed wwwprobe, a tool to measure client-perceived response time. wwwprobe acts as a mini-browser, downloading web pages, along with their embedded objects, much like general-purpose applications like GNU wget. However, wwwprobe measures the time taken for each step in an HTTP transaction, including DNS name resolution, connection establishment, server response time, and download time.

Project Member

Anees Shaikh

Publications

A. Shaikh, D.E. Martin, and Peter Gayek, "Impact of Network Factors on Web Performance," unpublished report, September 2001.