[Pdns-users] PDNS Recursor on Debian / Low performance !!!URGENT!!!!

bert hubert bert.hubert at netherlabs.nl
Sun Feb 6 13:34:36 UTC 2011

Hi!!!! Please se my answers below.

On Sun, Feb 06, 2011 at 12:35:35PM +0000, Maroon Ibrahim wrote:
> Dear PDNS Admins/Users
> I have installed PDNS Recursor on Debian Lenny 64-bit with kernel 2.6.32 (downloaded the PDNS Recursore .deb from www.powerdns.com webpage) and install it using dpkg -i pdn_recursor_3.3.deb 
> As for the setup, all went fine so far !!! 


> But i ran queryperf -q 4000 -d queries (3million record) -l 120 and I noticed lots of query timed out and ended up with a very bad result almost 143 qps !!!! 

If you want to run with 4000 parallel, which is a lot, you'll need to add
more filedescriptors on Linux. This can be achieved by setting 'ulimit -n
16384' before starting the recursor.

Can you try to reproduce your problem with -q 1000 first?

> Do I need to fine tune the kernel? or is there any tweaks in powerdns recursor i have missed ? do you recommend to manually compile powerdns recusor?? please advise 
> it is really urgent 

In addition, if you run with this many parallel queries, please read

Especially this bit about iptables.

Good luck!!!


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