CPU Usage Problem.

[Kevin Darcy]

This could be any number of things. If you're running out of physical
memory, then named might be causing your machine to swap, which could
drive up your CPU. To verify this, run some system performance
monitoring tool and watch your memory statistics. Alternatively, some
application on some client on your network -- or several of them at once
-- may be going crazy and bombarding your server with repetitive
queries. You could verify this by looking at the XSTATS or NSTATS that
named dumps to syslog periodically. To track down the actual source(s)
of this bombardment, though, you'd have to turn on debugging or a query
log. It's also possible, but less likely, that you're getting into some
sort of loop with another nameserver. Again, the XSTATS and/or debugging
output, would help to diagnose this situation. Lastly, if your cache is
really large, then maybe the CPU is spiking when it cleans it. In this
case, you should see "Cleaned cache of XXXXX RRsets" (where XXXXX is a
rather large number) in your logs at about the time the CPU is spiking.
To fix this, you should perhaps clean more frequently (see the
cleaning-interval option) to spread out the load, or maybe arrange for
the cache-cleaning to occur during non-peak periods.

Overall, you should get _DNS_and_BIND_ (3rd Edition at least) to help
you interpret those stats, troubleshoot performance problems, or just
generally to learn how to set up and operate DNS.


- Kevin

Mo kee-jin wrote:

> Hi guys.
>
> I got problem.
> Sometime DNS Server (BIND 8.2.2 P5) used too much CPU.
> One or twice per a week, It uses 90~97% of CPU.
> Commonly, It uses about 20%.
>
> What is the problem and how can I control it?
> Please help me.
>
> kjmo at lgeds.lg.co.kr
> +82-2-3773-1697