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soolus avatar Ubuntu

22.04.2 LTS very slow to respond to KVM switching

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soolus

The problem

Switching my KVM from my desktop to my laptop is usually a 30-60 second ordeal when it should take maybe a few seconds at worst.

The displays usually light up right away, complete with a mouse cursor. One of the displays, usually the left one, will dim if the mouse cursor isn't moved over it for a while. Moving the cursor around sometimes changes the pointer based on what's supposed to be under it -- text bar, link clicker finger, normal pointer, resize, etc. -- but this is inconsistent and seems to have some sort of delay to it.

Once the displays light up and actually render the desktop, it's often another 5-15 seconds before anything is actually responsive.

The setup

  • Desktop is whatever windows PC.
  • Laptop is running Ubuntu 22.04.2 LTS per /etc/issue on a Dell XPS 15 9520, outfit with the i9-12900HK, 2x32GB DDR5-4800, RTX3050Ti 4GB, and a 1tb NVMe drive.
  • Both desktop and laptop are fed via DisplayPort to a Level One Techs 3-port KVM to switch the three displays (two 4k, one 2560x1440) from machine to machine.
  • The 1440 and one 4k are fed through a Dell WD22TB4 dock, with the other 4k being fed directly from an available USB-C port on the laptop.

Troubleshooting performed

Switched out dock with two other different models -- no change.
Tested running Windows on the laptop, issue did not persist (so it isn't the laptop).
Tried different versions of the nvidia driver -- I forget which ones, but I am currently on nvidia-driver-525
The issue persists regardless of whether or not the laptop is locked - I usually leave it unlocked.

I've noticed that a fresh boot tends to be under 20 seconds to switch to the laptop, whereas if it's been on for something like 10 days it tends to take over a minute.

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in flag
matigo
Welcome to AskUbuntu. Generally one of the better places to look for reasons is in the system logs. `/var/log/syslog` may have some information regarding why issues exist, such as waiting for a device to time out or something else. Start there and, if nothing stands out, feel free to update the question to include this information
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