After trying to fix screen tearing, Xorg using up to 25% CPU. How can I fix this?

Dan C

1/9/24, 8:12 AM

Htop shows me /usr/lib/xorg/Xorg -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch is typically between 7% and 15% CPU, and about 150MB if memory. My CPU temperature hasn't gone below 50` while the computer's on, even at idle, for a month. Fan running constantly. My battery life (of course) also has tanked. Please help my find and undo my mistake!

I am running Ubuntu 20.04 Mate on a Thinkpad T460 laptop, with Intel integrated graphics. Installed 2+ years ago, and generally trouble-free.
Over the last couple weeks, I've been plagued by constant moderate CPU usage -- I'm a heavy browser user (100+ tabs) so it took me a while to realize this was happening even with browser closed, and even right after a cold start.

Best I can think of, I may have started this by trying to relieve the screen-tearing on a second monitor (HDMI). I followed instructions here, to create a new 20-intel.conf file with a couple different variations of settings. No variations were a success, and most were worse. I commented out all lines in that file, and ran like that for a couple weeks. Finally, I just renamed the file to .bak, and rebooted, but still have high Xorg CPU time.

Is there a way to revert to xorg's default options? Are there other places I can look for clues about why the heavy usage? What else could cause this, if not my tinkering?

Thanks for any help!

189

1 + 0

xorg

intel-graphics

20.04

Score:1

Ubuntu

sean

1/9/24, 9:14 AM

My primary guess is that you need to sudo apt purge lightdm at the very least, and then reinstall it. It's possible also that there is some crap in the /etc/xdg/autostart folder the lightdm may be trying to launch that no longer exists, so have a look there too. This can especially be the case if you did something like loaded xubuntu-desktop, gnome-desktop, or whatever and removed it. (Because you're using something else.) It might not have cleaned up the folder and trying to launch something that is missing a component over and over again and making it do that. (lightdm sort of launches everything up at the same time when it acquires the display like most display managers do.) Anyway, that should get you started in the right direction. If you specified any custom configurations to lightdm in the etc folder remove those too. Take everything out that you changed, and then go from there.

Secondly, this machine will always burn more cpu doing anything because it's nearly 8 years old. You may want to have a look at running a lighter desktop if you haven't already. Your tab use is insane. Use the bookmarks, close the tabs you're not immediately using. You can not only have bookmarks, but folders of bookmarks. Some browsers even let you load the whole folder at the same time and you can just group them into tasks and shoot them all off at once. This is burning a tremendous amount of cpu and power doing basically nothing. Browsers are pretty resource intensive for what they do... Every page is at least another 50-MB-250MB of memory... AT LEAST that much. This page is 40MB and there's nothing on it, Facebook or Twitter are like 300MB. Anyway, you don't want to run a ton of tabs if you can help it.

+ 5

Dan C

1/9/24, 9:48 PM

I will look into the various things in autostart to see what's up. I suppose I can also look for lightdm logs, now that I think about it, and see if anything is trying to start, or continually calling for a function, that's not working right. Hoping to not have to purge/reinstall but may have to resort to that.

Dan C

1/9/24, 9:59 PM

I was going to ask where to start for that, but I've found this Q&A looking at var/log/lightdm so will start looking in there, too: [https://askubuntu.com/questions/396957/] Hopefully things haven't changed much in 7 years (13.10 -> 20.04)! ~Now~ let me zealously defend my hardware choices =P This machine has been doing daily service for me just fine, even with this issue. I got it because it can run idle for 10+ hours, or 5+ with [my] regular heavy use I know ow ti runs and when I'm pushing it too far. Appreciate your cautions, but this works for me. And, it's currently 331 tabs ;)

sean

1/10/24, 12:26 AM

@DanC I'd never be able to find anything in that. :D Anyway, I have no problem with that series of laptops they're great machines and worked on them for the better part of a decade. They're very easy to repair, in contrast to newer models... Definitely, remove lightdm totally and pop it back. The worst that can happen is that it does the same thing again. :D

Dan C

2/1/24, 4:44 AM

[Time skip: 2+ days later] Alas -- this resolved itself within two days of asking this question, before I finished my travel-for-work and could risk tinkering a lot with the computer. I wish I'd had a chance to test this answer but was not able to say if this made a difference or not. If it ever recurrs, I'll definitely try it, and mark correct if it resolves the problem!

Dan C

3/18/24, 7:48 AM

Finally started seeing this again, (8-12% CPU) and tried purge and reinstall... alas, to no difference. Nothing obviously an error or loop in the /var/log/lightdm files either that i see. a couple dozen ".desktop" items in /etc/xdg/autostart -- most i recognize, but i guess trying that next.

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EN: After trying to fix screen tearing, Xorg using up to 25% CPU. How can I fix this?

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