BIND 9.x caching Performance under heavy loads

[Bernhard Schmidt]

On 2005-03-31, Bernhard Schmidt <berni at birkenwald.de> wrote:

> But still, the CPU hog is there, and the CPU hog is not explainable with
> the general difference in speed. After all, it is running fine for some
> days until CPU usage explodes. I'm running the non-threaded version now
> since one day, if it keeps running this way until next week the bug is
> related to threading.

I got some new results, maybe someone could point me to the options we
might have. 

The bug appeared with the multithreaded version as well as with the
non-threaded version. We removed the biiiig RBL zone from the server and
the bug still appeared. So far we did only find _one_ option which makes
our problem disappear:

	max-cache-size 300M;

if we set it to unlimited or to something higher than 300M (for example
400M) BIND starts burning the CPU within two days. Remind you that this
server has 4GB of RAM and is dedicated to this BIND process. No ulimits
are set.

Our next try will probably be to compile with
ISC_MEM_USE_INTERNAL_MALLOC. I read there are some (performance) issues
with this flag and running threaded, would it be wise to use the
non-threaded version and basically ignore three of four CPUs?

Thanks
Bernhard