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-   -   DisplayLinkManager high CPU usage (Ubuntu 18.04) (https://displaylink.org/forum/showthread.php?t=66257)

madscientist 09-08-2018 07:38 PM

DisplayLinkManager high CPU usage (Ubuntu 18.04)
 
I am seeing very high (30-50%) CPU usage from DisplayLinkManager on my Dell Precision 5520 running Ubuntu 18.04 with Gnome on X.org (not Wayland). This happens even if I don't have my laptop plugged into the DisplayLink!

By accident I seem to have discovered the culprit: if I have the Slack client running then DisplayLinkManager uses 50% CPU. As soon as I stop the Slack client, DisplayLinkManager CPU usage drops to 2-3%. If I start Slack again, it jumps back up immediately. Note if my screen locks and the displays go to sleep, then CPU usage goes back down even if Slack is running.

This is completely reproducible. I've not found any other software that does this (Chrome, Spotify, normal Linux apps) but that's not to say there aren't any! My laptop is at work so I won't be able to do more investigation this weekend, this is just an initial report.

I honestly can't understand why Slack would cause this problem, unless there's something odd/unique about the way it's using the display.

Anyway, I'd be interested to know if anyone else sees this issue with the Slack client. FWIW I installed the latest DEB version, not the Snap version, from https://slack.com/downloads/linux

madscientist 09-10-2018 04:31 PM

OK I configured my system as described in these two FAQ links:

https://support.displaylink.com/know...hen-displaylin

and:

https://support.displaylink.com/know...plication-only

Note that (a) I don't have an NVIDIA card, and (b) I'm using Ubuntu 18.04 while the latter FAQ entry says the screen freeze was in Ubuntu 17.10 and fixed in 18.04. Indeed I didn't have the screen freeze problem but that fix also appears to solve the flickering mouse issue.

Anyway, after rebooting with the above two changes, Slack no longer causes DisplayLinkManager to chew up my CPU like it did before.

I have not fully tested things but I'm hopeful things work now.

razcakappa 12-04-2018 07:06 AM

Thanks for sharing cand caring for keep the others updated
 
Quote:

Originally Posted by madscientist (Post 86636)
OK I configured my system as described in these two FAQ links:

https://support.displaylink.com/know...hen-displaylin

and:

https://support.displaylink.com/know...plication-only

Note that (a) I don't have an NVIDIA card, and (b) I'm using Ubuntu 18.04 while the latter FAQ entry says the screen freeze was in Ubuntu 17.10 and fixed in 18.04. Indeed I didn't have the screen freeze problem but that fix also appears to solve the flickering mouse issue.

Anyway, after rebooting with the above two changes, Slack no longer causes DisplayLinkManager to chew up my CPU like it did before.

I have not fully tested things but I'm hopeful things work now.

Thank you very much for posting the findings. I'm also using DisplayLink device with ElementaryOS (Ubuntu Xenial based release) installed on a Macbook Air, and faced to the same issue set.
And noticed the miracle when killing the Slack and the CPU clams down.

Also followed the FAQ solutions and AFAIK the issue is gone for good. Lets see on future.

fightling 12-07-2018 05:33 PM

Thank you so much for this fix, madscientist!!!! Displaylink was burning my CPU since I updated to Ubuntu 18.04. Now CPU consumption seems to be on a reasonable level again.


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