Seemingly random render and input lag

[williamleven]

After some time connected to a docking station, the computer would randomly about 4 times a minute experience extrema lag spikes, with rendering and input devices freezing or stuttering for a few seconds. Spikes vary from lasting upwards of 5 seconds to only a few milliseconds and behaviors have been observed to be worse while running heavy applications.

Debugging

1. CPU usage seems to be moderate with slight spikes in conjunction with the lag spikes.
2. Several short lives processes running /bin/sh -c echo 13b1 0bdc > /sys/bus/usb/drivers/brcmfmac/new_id seems to coincide with the lag-spikes
3. These processes are child processes of systemd-dbus
4. Inspecting the systemd-dbus debug log (/usr/lib/systemd/systemd-udevd -D) we can confirm that these executions are triggered by the /usr/lib/udev/rules.d/30-linksys-ae1200.rules rule.
5. Checking the kernel event log (udevadm monitor) we can see that this rules is triggered intermittently by the creation of virtual networks /devices/virtual/net/veth3...
6. Names of these networks seems to correspond with docker network devices, they can be listed with systemctl list-units | grep sys-devices-virtual-net-veth
7. Stopping all running docker containers and deleting their networks stops the kernel event activity and also remedies the lag spikes

Upstream

No upstream project seems to have any issues logged for this problem.

TODO

• 1. Investigate if podman is effected
• 2. Create reproducible example
• 3. Report to upstream
• 4. Disable or modify the /usr/lib/udev/rules.d/30-linksys-ae1200.rules rule.