[Pdns-announce] Performance problems with the RPM/.DEBs we supply, solution

bert hubert bert.hubert at netherlabs.nl
Thu Jul 28 16:47:35 UTC 2005

Hi everybody, 

If you are trying to achieve high performance on Linux, and it is not
working with a .deb or RPM we supply, the following applies to you. This
matters even more to SMP systems. From http://doc.powerdns.com/nptl.html :

 To get the best performance under Linux, especially on SMP systems, the use
 of NPTL is advised. The difference in performance can be over a factor of
 ten in some circumstances.

 NPTL is the default library on modern Linux distributions, so there is
 generally not a problem, except if you use a statically compiled version
 that, for portability reasons, defaults to LinuxThreads. This includes all
 .deb's and .rpm's provided by us up to and including 2.9.18.

 When running a PowerDNS-provided static binary of 2.9.18 or lower, it may
 make sense to recompile, or to upgrade to a newer version, if available.
 When recompiling, be sure to use a supported compiler, like g++ >3.2. You
 might also consider moving to a distribution supplied version.

 A good indication that your installation might benefit from such an upgrade
 is to watch the 'cs' count in the output of vmstat 1. If this is very high
 (> 10000), you are suffering from a LinuxThreads performance problem called

 Thanks are due to L. Bunt Jackson who noted the static compilation problem
 in an article in Dr. Dobb's Journal. 

Just a heads up.

http://www.PowerDNS.com      Open source, database driven DNS Software 
http://netherlabs.nl              Open and Closed source services

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