https://bugs.kde.org/show_bug.cgi?id=505554
Bug ID: 505554
Summary: Disconnecting from USB-C dock increases CPU and GPU
utilization by plasmashell and kwin_wayland
Classification: Plasma
Product: plasmashell
Version First 6.3.5
Reported In:
Platform: Fedora RPMs
OS: Linux
Status: REPORTED
Severity: minor
Priority: NOR
Component: general
Assignee: plasma-b...@kde.org
Reporter: accountsver...@hotmail.com
CC: k...@davidedmundson.co.uk
Target Milestone: 1.0
SUMMARY
Typically while idling at the desktop with no programs opened by the user, my
laptop (AMD 7840U with 780M) will report 3-4w usage by the SOC. I can connect
to a USB-C dock with external monitor, and nothing will change. In this state,
GPU fully downclocks, CPU and GPU utilization reported for plasmashell both sit
at 0% (aside from intermittent spikes), and CPU for kwin_wayland averages 0% as
well.
However, if I then disconnect from the USB-C dock after having been connected,
reported SOC power usage will jump to 8-9w, radeontop reports the GPU does not
clock down, SOC temperatures rise and fans ramp. When I looked for the cause, I
noticed plasmashell will sit at reported 11-15% GPU utilization and around 10%
CPU utilization, while kwin_wayland jumps between 5% and 50% CPU utilization,
as reported by top.
This load will continue indefinitely until I:
a) reconnect to USB dock
b) restart kwin_wayland (systemctl --user restart plasma-kwin_wayland.service)
c) reboot the laptop
Once I take any of the 3 above actions, CPU usage by kwin_wayland and both CPU
and GPU usage by plasmashell will drop to 0% again while system is idle, and
power and clocks drop accordingly. However, if the way I resolve is to restart
kwin_wayland, the usage will come back if I plug something other than the dock
into the USB port. Rebooting the laptop and reconnecting to dock resolve
indefinitely (at least until the next time I connect to and disconnect from the
dock).
STEPS TO REPRODUCE
1. Connect to a USB-C dock which has external monitor attached (via HDMI)
2. Disconnect from the dock
OBSERVED RESULT
System idle power consumption jumps by 5w, constant low GPU and CPU load by
plasmashell and CPU load by kwin_wayland, even while system is doing nothing.
EXPECTED RESULT
System will idle at same power and clocks as it did before and while it was
connected to the dock, no/low compute consumption by kwin_wayland and
plasmashell while at idle.
SOFTWARE/OS VERSIONS
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: Fedora Linux 42
KDE Plasma Version: 6.3.5
KDE Frameworks Version: 6.14.0
Qt Version: 6.9.1
ADDITIONAL INFORMATION
Example outputs before unplug:
lm sensors:
sensors amdgpu-pci-c100 cros_ec-isa-0000
amdgpu-pci-c100
Adapter: PCI adapter
vddgfx: 856.00 mV
vddnb: 856.00 mV
edge: +37.0°C
PPT: 8.04 W (avg = 4.13 W)
cros_ec-isa-0000
Adapter: ISA adapter
fan1: 0 RPM
local_f75303@4d: +26.9°C
cpu_f75303@4d: +28.9°C
ddr_f75303@4d: +26.9°C
cpu@4c: +39.9°C
# from nvtop
GPU[ 0%] MEM[||||||||| 0.608Gi/2.000Gi]
GPU 800MHz MEM 1600MHz TEMP 34°C CPU-FAN POW 4 W
PID USER DEV TYPE GPU GPU MEM CPU HOST MEM Command
3030 user 0 Both G+C 0% 250MiB 12% 0% 523MiB
/usr/bin/plasmashell --no-respawn
After disconnecting from dock (continues indefinitely until action is taken):
lm sensors:
sensors amdgpu-pci-c100 cros_ec-isa-0000
amdgpu-pci-c100
Adapter: PCI adapter
vddgfx: 849.00 mV
vddnb: 940.00 mV
edge: +44.0°C
PPT: 9.24 W (avg = 8.17 W)
cros_ec-isa-0000
Adapter: ISA adapter
fan1: 2693 RPM
local_f75303@4d: +43.9°C
cpu_f75303@4d: +41.9°C
ddr_f75303@4d: +41.9°C
cpu@4c: +45.9°C
#nvtop
PID USER DEV TYPE GPU GPU MEM CPU HOST MEM Command
2973 user 0 Both G+C 13% 277MiB 14% 8% 536MiB
/usr/bin/plasmashell --no-respawn
#top
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2718 user -2 0 2737916 311212 226292 S 8.3 0.3 3:09.24
kwin_wayland
2973 user 20 0 10.0g 549748 215192 S 7.3 0.6 0:46.07
plasmashell
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