High Latency During Peak Periods on Unbound Recursive DNS

[sir izake]

Hello

Anyone faced this problem?  High latency is usually between 7pm - 9:30PM.
Cache hit rate is low within this period too.

Regards,
Isaac

On Fri, Aug 11, 2023 at 11:55 PM sir izake <sirizake at gmail.com> wrote:

> Hi Everyone
>
> I am running a recursive anycast DNS for  over 15m subscribers in a
> telecom/isp environment. I have 7 HP servers running Freebsd 13.2, Unbound
> DNS 1.17.1 & Quagga.
>
> I have  tuned the OS  and applied Unbound DNS optimization recommendations
> for busy servers.
> NLnet Labs Documentation - Unbound - Howto Optimise
> <https://nlnetlabs.nl/documentation/unbound/howto-optimise/>
>
> additions to /etc/sysctl.conf
> # set to at least 25MB for 10GE hosts
>    kern.ipc.maxsockbuf=26214400
>    # set autotuning maximum to at least 25MB too
>    net.inet.tcp.sendbuf_max=26214400
>    net.inet.tcp.recvbuf_max=26214400
>    # enable send/recv autotuning
>    net.inet.tcp.sendbuf_auto=1
>    net.inet.tcp.recvbuf_auto=1
>    # increase autotuning step size
>    net.inet.tcp.sendbuf_inc=16384
>
>
> Servers performed very well (peak/off peak) with latency under 50ms until
> recently  when I enabled dnssec validation.
> https://nlnetlabs.nl/documentation/unbound/howto-anchor/
>
> Since then performance has been erratic with latency spiking to over 600ms
> during peak hours.
>
> I have disabled dnnsec validation and restarted unbound service / server
> several times. But the performance is not as good as before.
>
> Can anyone suggest any tuning/optimization parameter to implement?
>
> Hardware specs
>
> hw.machine: amd64
> hw.model: Intel(R) Xeon(R) Gold 6334 CPU @ 3.60GHz
> hw.ncpu: 32
> hw.byteorder: 1234
> hw.physmem: 549395005440
> hw.usermem: 546043224064
> hw.pagesize: 4096
>
> Regards,
> Isaac
>
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