realtime profile seems to include throttling the network speed to 100Mbs on low traffic

[lbckmnn]

I had some issues with a network interface going down for a couple of seconds which I eventually tracked down to tuned.

From the log:

2025-10-06 17:03:05,398 INFO     tuned.daemon.daemon: static tuning from profile 'realtime' applied
2025-10-06 17:03:55,426 INFO     tuned.plugins.plugin_net: enp2s0: setting 100Mbps
2025-10-06 17:03:55,435 INFO     tuned.plugins.plugin_net: enp3s0: setting 100Mbps
2025-10-06 17:03:55,435 INFO     tuned.plugins.plugin_net: enx000ec664fa6f: setting 100Mbps
2025-10-06 17:20:05,725 INFO     tuned.plugins.plugin_net: enx000ec664fa6f: setting max speed
2025-10-06 17:21:05,756 INFO     tuned.plugins.plugin_net: enx000ec664fa6f: setting 100Mbps

I also found this:
https://bugzilla.redhat.com/show_bug.cgi?id=1026359
which suggests that this behavior is expected in the powersave profiles.

I am however using the realtime profile.

What is the expected behavior in the realtime profile?

[yarda]

Do you use the default setting with the dynamic tuning disabled?

$ grep dynamic_tuning /etc/tuned/tuned-main.conf
dynamic_tuning = 0

[lbckmnn]

I am using the default config shipped with the debian package, which has dynamic tuning enabled.
Disabling dynamic tuning fixes the problem.
I am not sure why the default debian config has dynamic tuning enabled.
(Edit: it is disabled on trixie and i also found commit 2306cbd, so the config from bookworm is probably just older)

However, wouldn't it be sensible to put

[net]
enabled=false

as described here, into the network-latency profile or the realtime profile or does this also disable some desired static tuning?

[yarda]

Yes, this may also work, it will disable the whole net plugin so it depends on the profile you use. E.g. with the powersave profile which doesn't set anything there, it should be safe, but e.g. with the realtime profile which has:

[net]
channels=combined ${f:check_net_queue_count:${netdev_queue_count}}

You will lost the combined channels setting which may affect performance.

The dynamic_tuning = 0 is upstream default since tuned-2.22.0: 2306cbd