Evaluating the performance of user-space and kernel-space web servers

ABSTRACT

There has been much debate over the past few years about the practice of moving traditional user-space applications, such as web servers, into the kernel for better performance. Recently, the user-space userver web server has shown promising performance for delivering static content. In this paper we first describe how we augmented the userver to enable it to serve dynamic content. We then evaluate the performance of the userver and the kernel-space TUX web server, using the SPECweb99 workload generator under a variety of static and dynamic workloads. We demonstrate that the gap in the performance of the two servers becomes less significant as the proportion of dynamic-content requests increases. In fact, for workloads with a majority of dynamic requests, the µserver outperforms TUX. We conclude that a well-designed user-space web server can compete with an in-kernel server on performance, while retaining the reliability and security benefits that come from operating in user space. The results presented in this paper will help system developers and administrators in choosing between the in-kernel and the user-space approach for web servers.

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INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.5 COMPUTER SYSTEM IMPLEMENTATION
      C.5.5 Servers

Additional Classification:
  C. Computer Systems Organization
  C.1 PROCESSOR ARCHITECTURES
      C.1.3 Other Architecture Styles
          Subjects: Adaptable architectures

  H. Information Systems
  H.3 INFORMATION STORAGE AND RETRIEVAL
      H.3.5 On-line Information Services
          Subjects: Web-based services
  H.5 INFORMATION INTERFACES AND PRESENTATION (I.7)
      H.5.3 Group and Organization Interfaces
          Subjects: Web-based interaction