[dnsdist] Performance/tuning sanity check

[Dan McCombs]

Thanks Remi! I'm glad you noticed that message hadn't gone through.

I'll take a look at what you mentioned, I wasn't even aware of the CPU
options for addLocal.

I spent some time looking through the thread Nicolas shared at
https://mailman.powerdns.com/pipermail/dnsdist/2017-April/000281.html of
his performance tuning experience. Do you know if it's still the case in
newer versions of dnsdist to need multiple instances of dnsdist running on
a machine this size (32 cores) rather than just additional listeners via
addLocal to really push past 400kQPS? I just want to make sure I'm not
working off out-of-date information.

Thanks again,

-Dan

On Tue, Jan 3, 2023 at 10:43 AM Remi Gacogne via dnsdist <
dnsdist at mailman.powerdns.com> wrote:

> Hi Dan, Klaus,
>
> I just noticed I messed up with my previous response and it never made
> it to the list, so I'm re-posting it now.
>
> I don't see anything wrong with your configuration, Dan. You could look
> at the metrics to see if you are experiencing contention in the
> packet-cache and ring-buffers, and increase the number of shards in that
> case.
>
> Other than that, I agree with Klaus that tuning the system itself
> becomes necessary above 400k QPS.
> In addition to IRQ balance, I would suggest looking at:
> - increasing receive and send buffers: see [1]
> - unloading any module related to connection tracking
> - setting a proper UDP flow load-balancing policy, see 'ethtool
> rx-flow-hash udp4 sdfn' and the likes
> - setting up CPU pinning [2] so that 1/ all dnsdist threads are on the
> same NUMA cores 2/ dnsdist receivers threads are on the CPU cores
> handling NIC receive queues (which might involve disabling IRQ balance
> and directly assigning the IRQ affinity for the NIC queues)
>
> Hope that helps,
>
> [1]: https://dnsdist.org/reference/tuning.html#setUDPSocketBufferSizes
> [2]: see the cpus option on
> https://dnsdist.org/reference/config.html#addLocal
>
> --
> Remi Gacogne
> PowerDNS.COM BV - https://www.powerdns.com/
> _______________________________________________
> dnsdist mailing list
> dnsdist at mailman.powerdns.com
> https://mailman.powerdns.com/mailman/listinfo/dnsdist
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.powerdns.com/pipermail/dnsdist/attachments/20230103/9b262db9/attachment.htm>