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Tasklist

FS#70549 - System slows down after unplugging external display on Thinkpad L14 with i915 graphics

Attached to Project: Arch Linux
Opened by awal (awal) - Thursday, 22 April 2021, 18:14 GMT
Last edited by Andreas Radke (AndyRTR) - Monday, 26 April 2021, 11:42 GMT
Task Type Bug Report
Category Packages: Extra
Status Assigned
Assigned To Andreas Radke (AndyRTR)
Jan Alexander Steffens (heftig)
Laurent Carlier (lordheavy)
Architecture x86_64
Severity Medium
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 0%
Votes 0
Private No

Details

Description:

This issue is somewhat related to https://bugs.archlinux.org/task/70516 but different enough so I'm filing a separate report here.

- After I unplug my external display (connected over USB-C, if it matters), the system gradually slows down and all operations take a significant amount of time.
- For example, opening a new browser tab takes a few seconds (both firefox and chromium), opening rofi and dmenu also takes a second or two.
- When the xrandr display is turned --off, the problem gradually goes away.
- During this time, memory (mostly virtual, but sometimes RES as well) and CPU usage of graphical applications (mpv, dmenu, rofi, firefox, X, i3) is somewhat high. However, no individual application is an outlier.
- The issue is not specific to any of the graphical applications. I can reproduce it almost consistently with each of those not running.
- I have recorded strace'ed invocations of a dmenu based script with timings for each syscall. In my cursory read, no specific syscall seems to slow down disproportionately compared to the others. However, I'd be happy the attach the logs here if anyone wants to investigate.

Additional info:
* package version(s)
- linux 5.11.14.arch1-1
- intel-ucode 20210216-1
- xorg-server 1.20.11-1
* config and/or log files etc.
- nothing in dmesg/journal/xorg logs
* link to upstream bug report, if any
- na

Steps to reproduce:

1. Connect external display over USB-C and enable it with xrandr.
2. Use the machine for a little while.
3. Unplug the cable but don't disable the display with xrandr's --off.
4. System gradually slows down.
This task depends upon

Comment by awal (awal) - Thursday, 22 April 2021, 18:41 GMT
Forgot to mention, I switched to the LTS kernel yesterday after the recommendation on the linked bug, but the issue persists on the LTS kernel as well.

linux-lts 5.10.31-1
Comment by Andreas Radke (AndyRTR) - Sunday, 19 September 2021, 09:01 GMT
Is this still an issue?
Comment by awal (awal) - Sunday, 19 September 2021, 10:50 GMT
Yes, this still happens. How can I help investigate?
Comment by Andreas Radke (AndyRTR) - Sunday, 19 September 2021, 14:20 GMT
I guess the best place is to get in touch with upstream Intel DRM team via the IRC(oftc) or
libdrm (https://gitlab.freedesktop.org/mesa/drm) or kernel drm (https://gitlab.freedesktop.org/drm/intel/-/issues).
Comment by awal (awal) - Tuesday, 05 October 2021, 14:20 GMT

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