Low Throughput Issue with unbound DNS over TLS on Ubuntu 22.04 about unbound

[Ji-Peng]

Now that it's late at night in China, I can use the Libevent library to link and rerun unbound on my 22.04 system tomorrow

[gthess]

If I understand correctly you are using the exact same version of Unbound built from source on two different systems with different results. Could you share your configure command? If you have a running Unbound at the moment, unbound -V would also include it.

[Ji-Peng]

Thank you for your response. Upon reviewing my previous records, I found that the configuration command I used was ./configure --with-ssl=/root/local-eng25519, specifying only my custom OpenSSL directory.

I happen to have a Ubuntu 22.04 machine available now, so I will attempt to replicate this issue.

[Ji-Peng]

I have now fully replicated the issue. Please let me know what information you need from me.

[Ji-Peng]

I've documented nearly all commands and their corresponding outputs when replicating this issue. Please take a look at the debug_unbound. It contains ample information.

If the above details are still insufficient, please let me know what additional information you need.

[gthess]

Thanks for this! I can already spot something that my coworker also thought would be an issue:

Linked libs: mini-event internal (it uses select), OpenSSL 1.1.1q  5 Jul 2022

Is mini-event also used on a 20.04 system?

[Ji-Peng]

Yes, all configurations are same on Ubuntu 20.04.

[gthess]

I wasn't clear enough or your answer is not clear to me :)
I meant to ask if you get the same output for the unbound -V command on a 20.04 system.

[Ji-Peng]

Sorry, I don't have a ubuntu20.04 system to run unbound right now, I just remember that the operation flow including all the commands on the ubuntu20.04 system is exactly the same

[gthess]

No worries, I'll try to replicate on 20.04 and come back to this.

[Ji-Peng]

I've used libevent to link and rerun the previously described experimental steps. Here's the configuration: ./configure --with-ssl=/root/local-eng25519 --with-libevent.

The output of the unbound -V command is as follows:

Version 1.19.4

Configure line: --with-ssl=/root/local-eng25519 --with-libevent
Linked libs: libevent 2.1.12-stable (it uses epoll), OpenSSL 1.1.1q  5 Jul 2022
Linked modules: dns64 respip validator iterator

BSD licensed, see LICENSE in source package for details.
Report bugs to [email protected] or https://github.com/NLnetLabs/unbound/issues

Unfortunately, the final throughput remains the same, still close to 20 connections/second.

[Ji-Peng]

Has there been any further progress regarding this issue?

[gthess]

I verified that mini-event is also used with a default 20.04 system but I can look further on reproducing next week.

[gthess]

I can reproduce the exact same behavior but not sure what is happening. I am comparing 20.04 and 24.04 btw; 24.04 is slow.
The last thing I noticed that is different with tcpdump is that your client seems to be sending RST packets in 24.04. Haven't investigated further though yet.