Arch Linux

kiskiller0

Member

Registered: 2023-01-23

Posts: 6

relatively high cpu usage by Xorg in i3wm supposedly caused by lightdm

this process:
/usr/lib/Xorg :0 -seat seat0 -auth /run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch

shows high cpu usage, so even in my lightweight setup (i3wm) the cpu is always > 5% even if the computer is doing literally nothing.

I followed the Lightdm article in the archlinux website to configure my Lightdm to autologin, and to login without a password, I also use a background image in Lightdm, I think this is all the relevant info, as I don't tinker with my system that much, I have dm-tool and i3lock bound to keyboard shortcuts, but I suppose they aren't running in the background always. 

N.B: previously, my cpu usage was practically 0%.

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 76,690

Re: relatively high cpu usage by Xorg in i3wm supposedly caused by lightdm

supposedly … previously

You might want to elaborate on conclusion and what changed.
Does the CPU load vanish w/o lightdm?

Please post an xorg log and the output of "loginctl session-status",  https://wiki.archlinux.org/title/Xorg#General
CPU load in the X11 server is typically caused by some client, so despite the load being pot. async, that client will likely show up in top as well.

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V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,285

Re: relatively high cpu usage by Xorg in i3wm supposedly caused by lightdm

"This process" is simply xorg. "Basically doing nothing", do you have some kind of panel showing any kind of data like the clock or other system info and how is that configured, which refresh intervall?

kiskiller0

Member

Registered: 2023-01-23

Posts: 6

Re: relatively high cpu usage by Xorg in i3wm supposedly caused by lightdm

"This process" is simply xorg. "Basically doing nothing", do you have some kind of panel showing any kind of data like the clock or other system info and how is that configured, which refresh intervall?

I have i3blocks with blocks updating at different intervals, for instance the "cpu_usage" block updates at an interval of 1 second.
I want to exclude it as a possible reason because:

1. I used to use it before the problem to track cpu usage
2. the process mentions Lightdm as a perpetrator (although you can argue that Lightdm is the one that launches i3wm and i3blocks)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,285

Re: relatively high cpu usage by Xorg in i3wm supposedly caused by lightdm

The process mentions lightdm as the authenticator for the xorg instance, which is normal since lightdm is starting xorg. What you see is the xorg process, for all intents and purposes lightdm is irrelevant there.

Please try to answer and provide the details seth asked for. If I had to guess and this suddenly happened "lol, simpledrm" https://bbs.archlinux.org/viewtopic.php?id=288009 (rant: seriously... what problem does the simpledrm driver seek to solve?)