Caching DNS server (bind9.4.2) CPU usage is so so so high.

[Dave Sparro]

On 4/25/2010 10:23 PM, Trần Trọng Tấn wrote:
>
>
> Hi, I have a caching-only dns server which get ~3k queries per second.
> Here is specs:
>
> |Xeon  dual-core2,8GHz  4GB  of RAM
>
> Centos  5x  32bit(kernel2.6.18-164.15.1.el5PAE)
>
> bind9.4.2
> |
>
> rndc status: recursive clients: 666/4900/5000
>
> Bind always uses 100% on one core on single-thread config. After I
> recompiled it to multi-thread, it uses nearly 200% on two core :( No
> iowait, only sys and user. I searched around but didn't see any info
> about how bind use CPU. Why does it become bottleneck?
>

Upgrade.  BIND 9.5 has some pretty big changes to the way the cache is 
handled.  You may be able to make some adjustments to the 'cache 
cleaning interval' in your current configuration, but that won't really 
fix the problem I suspect you are seeing.

**NOTE**
the BIND 9.5.x branch is actually pretty old, I'd suggest skipping it 
and going right to one of newer Extended Support Versions (9.6 or 9.7).