UDP Load balancer does not scale

[Maxim Konovalov]

Hello,

On 16/05/2017 10:10, ajmalahd wrote:
> Hi
> 
> I am trying to set up a UDP load balancer using Nginx. Initially, I
> configured 4 usptream servers with two server processes running on each of
> them.
> It gave a throughput of around 24000 query per second when tested with
> dnsperf. When I try to add two more upstreams servers, the throughput is not
> increasing as expected. In fact, it deteriorates to the range of 5000 query
> per second with the following error:
>
[...]

With adequate hardware you should expect at least 10x more.

I would double check if you are not CPU bound on the server and
client side (yes, I read your note about that but it's worth to
check again).  It could be that nginx uses just one worker/cpu.
Same about the client.

Then check if no bottleneck at the network layer / UDP with your
preferred tool. Check the OS network metrics for any obvious limits.

Also, it makes sense to read the following great slides about udp
perf tuning from Toshiaki Makita from NTT:

http://textlab.io/doc/15478046/boost-udp-transaction-performance

-- 
Maxim Konovalov