Higher idle CPU usage

adiosocelote · 2026-08-25 17:21:29

First off, I want to apologize if this was already posted, but I could not find any information about it using Google, Brave search and AIs (I know, I have sinned for using AI).

I noticed about a month ago that, on my AMD system, my idle CPU usage got higher. I am on a rather minimal installation, still on X11 using dwm and a few of my hand-written programs that I thought are the issue, because at the same time when it happened (the spikes), I was toying with said programs. I ruled out they are not the issue and neither is X11, by launching a clean TTY (no graphical environment whatsoever) and launching a stripped down version of my "widget manager" that only showed CPU usage, and the CPU usage was at a constant 1% in a clean TTY. Unfortunately, I do not know what said CPU usage is otherwise, because I never ran such "inspection" before.

The CPU usage is generally the same, unless idle. Idle CPU usage used to be 0.017% to 0.083% (yes, zero dot zero seventeen and zero dot zero eighty three), and now they are at 0.216% to 0.399%. Again, any other CPU usage percentages are the same – watching something through mpv and listening to music on cmus (at the same time) equals to 0.6% to 3% CPU usage, no change compared to a month ago or a year ago. Games that ate 50% of my CPU still eat 50% of my CPU, only idle times affected.

When did I notice it exactly? Can not tell for sure, because my memory is shit, but around last week of July, there was an update to Linux kernels (regular and LTS) and firmware updates. I noticed the idle CPU being higher only about 2 or 3 days later. There were updates to both kernels quite frequently, throughout the month, which lead me to believe everyone knows about this issue. However, around a month has passed, no changes.

Here is my Fastfetch output, if this helps at all (I did not trim it just in case):

Board: X570 Pro4
CPU: AMD Ryzen 5 3600 (12) @ 4.21 GHz
GPU: AMD Radeon RX 6700 XT [Discrete]
Physical Disk (Samsung SSD 970 EVO Plus 1TB): 931.51 GiB [SSD, Fixed]
Monitor (S24R35x): 1920x1080 px @ 71.91 Hz - 521x293 mm (23.53 inches, 93.61 ppi)
Monitor (HP E221c): 1920x1080 px @ 60 Hz - 497x292 mm (22.69 inches, 97.07 ppi)
BIOS (UEFI): P2.30 (5.14)
----------------
OS: Arch Linux x86_64
Kernel: Linux 6.18.46-1-lts
Processes: 289
Packages: 10 (flatpak), 1102 (pacman)
LM: login (TTY)
WM: dwm (X11)
Shell: zsh 5.9.2
Terminal: tmux 3.7c
Terminal Size: 240 columns x 61 rows (1920px x 1037px)
Vulkan: 1.4.354 - radv [Mesa 26.2.1-arch1.1]
OpenGL: 4.6 (Compatibility Profile) Mesa 26.2.1-arch1.1
----------------
Display (S24R35x): 1920x1080 in 24", 72 Hz [External] *
Display (HP E221c): 1920x1080 in 23", 60 Hz [External]
Theme: Adwaita-dark [GTK2/3/4]
Icons: Obsidian-Amber-Light [GTK2/3/4]
Font: Ubuntu (10pt) [GTK2/3/4]
Cursor: Adwaita

If there is something else I should post, let me know. But I think this is the issue of the firmware, because both regular kernel (pacman -Si linux) and linux-lts have the same problem.

Oh, and about updates: I `sudo pacman -Syu` every day. Rarely I miss a day to update my system. This is just preference on my part. I also do not run any additional programs that run permanently. If I do, I always close them first, then try to debug other things that need to run (unless anything system related – then I do not touch it). And because the CPU usage is only different when idle, well, can not be on my end.

I might be slow with responding, so if I do not respond within a week, this is normal. Blame my mom for birthing me that way – I might be busy with other things and life and forget.

PS: I use Arch, by the way.

seth · Today 16:20:44

Measured how and in which process?
You can try to downgrade the kernel from the https://wiki.archlinux.org/title/Arch_Linux_Archive to see whether this is coming from there an with what version.

Partially downgrading the kernel is, within reason and unlike most other packages possible as it's largely self-contained.
I'd still keep a second kernel around (ie. downgrade either the main or the LTS kernel, not both) in case you don't want to chroot from the install iso in the worst case scenario.

Arch Linux

#1 2026-08-25 17:21:29

Higher idle CPU usage

#2 Today 16:20:44

Re: Higher idle CPU usage

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