Re: [PATCH] dnscache: merge similar outgoing udp packets

On Thu, Apr 23, 2009 at 10:48:00AM +0200, Krzysztof Gajdemski wrote:

> I've just tested Your patch in rather loaded dnscache cluster. Patched
> dnscache was installed on only one server within the cluster so
> performance between patched and unpatched version could be easily
> compared. During a period of testing (about one hour) I had no visible
> name resolving problems. Query merging engine also worked just fine.
> Unfortunately, there was a serious performance issue. 

I am not too surprised by that. The data structures are very naive, so
for a heavily loaded dnscache, you end up with some O(MAXUDP^2)
behavior.  I'll try to take some measurements, and then replace the
main linear search for duplicate matching with something with better
algorithmic complexity.

Thanks for the report.

-Peff