Check out the new USENIX Web site.

USENIX, The Advanced Computing Systems Association

2006 USENIX Annual Technical Conference Abstract

Pp. 115–128 of the Proceedings

Implementation and Evaluation of Moderate Parallelism in the BIND9 DNS Server

Tatuya Jinmei, Toshiba Corporation; Paul Vixie, Internet Systems Consortium


Suboptimal performance of the ISC BIND9 DNS server with multiple threads is a well known problem. This paper explores practical approaches addressing this long-standing issue. First, intensive profiling identifies major bottlenecks occurring due to overheads for thread synchronization. These bottlenecks are then eliminated by giving separate work areas with a large memory pool to threads, introducing faster operations on reference counters, and implementing efficient reader-writer locks. Whereas some of the solutions developed depend on atomic operations specific to hardware architecture, which are less portable, the resulting implementation still supports the same platforms as before through abstract APIs. The improved implementation scales well with up to four processors whether it is operating as an authoritative-only DNS server, with or without dynamic updates, or as a caching DNS server. It also reduces the memory footprint for large DNS databases. Acceptance of this new sever will also have a positive side effect in that BIND9, and its new features such as DNSSEC, should get wider acceptance. The direct result has other ramifications: first, the better performance at the application level reveals a kernel bottleneck in FreeBSD; also, while the results described here are based on our experience with BIND9, the techniques should be applicable to other thread-based applications.
  • View the full text of this paper in HTML and PDF. Listen to the presentation in MP3 format.
    Click here if you have forgotten your password Until June 2007, you will need your USENIX membership identification in order to access the full papers. The Proceedings are published as a collective work, © 2006 by the USENIX Association. All Rights Reserved. Rights to individual papers remain with the author or the author's employer. Permission is granted for the noncommercial reproduction of the complete work for educational or research purposes. USENIX acknowledges all trademarks within this paper.

  • If you need the latest Adobe Acrobat Reader, you can download it from Adobe's site.
To become a USENIX Member, please see our Membership Information.

Last changed: 15 Sept. 2006 ch