Bug 497632 - Flaky performance with multiple displays (3+)?
Summary: Flaky performance with multiple displays (3+)?
Status: RESOLVED UPSTREAM
Alias: None
Product: kwin
Classification: Plasma
Component: multi-screen (other bugs)
Version First Reported In: 6.2.4
Platform: Neon Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords: multiscreen
Depends on:
Blocks:
 
Reported: 2024-12-18 00:03 UTC by Jeff Beardsley
Modified: 2025-05-26 13:18 UTC (History)
5 users (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


Attachments
jbeard-dmesg-output (116.92 KB, text/plain)
2025-05-23 21:44 UTC, Jeff Beardsley
Details
jbeard-drm-info (87 bytes, text/plain)
2025-05-23 22:06 UTC, Jeff Beardsley
Details
drm_info for x11 occurrence of the reported issue (203.04 KB, application/octet-stream)
2025-05-25 23:36 UTC, Jeff Beardsley
Details
kwin-journal for x11 occurrence of the reported issue (1.40 KB, text/plain)
2025-05-25 23:37 UTC, Jeff Beardsley
Details
dmesg for x11 occurrence of the reported issue (136.28 KB, text/plain)
2025-05-25 23:37 UTC, Jeff Beardsley
Details

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Description Jeff Beardsley 2024-12-18 00:03:53 UTC
SUMMARY

After being "locked" for awhile, upon unlocking, one of my three displays will turn off, after blinking on and off (slowly) for a few seconds. It's usually the right-most display in my case, though it's *sometimes* the middle display.  For a long time I thought it was hardware.  I used to reboot whenever this happened, and cuss while it was booting, ....  

I have discovered though, that it can be restored quite easily (though it still causes some language :).

* Launch Display Configuration (via desktop context menu).
* In the "Drag screens to re-arrange them" area, select the offending display/screen
* Uncheck the "Enabled" checkbox below, and hit "Apply".
* Momentarily a small dialog asks you you if you want to "Keep" or "Restore" the setting.
* Selecting "Restore" (or letting the time run out) will restore the setting, and put it back into a working state.

STEPS TO REPRODUCE
I don't know how to cause this to happen, but I see it every couple days, sometimes more  than once in a day.
I am certain some other developers out there (having 3 or more displays) have seen this issue. 

This may be the same on Wayland, but I've only seen it on X11, because I cannot run Wayland with Eclipse IDE (which I use for work)

SOFTWARE/OS VERSIONS

Operating System: KDE neon 6.2
KDE Plasma Version: 6.2.4
KDE Frameworks Version: 6.9.0
Qt Version: 6.8.1
Kernel Version: 6.8.0-51-generic (64-bit)
Graphics Platform: X11
Processors: 32 × AMD Ryzen 9 7950X 16-Core Processor
Memory: 46.7 GiB of RAM
Graphics Processor: AMD Radeon RX 6600
Manufacturer: ASUS
Comment 1 Nate Graham 2024-12-18 17:47:09 UTC
Some questions:
1. What's the make and model of the affected screen?
2. Is it always just this screen, even if you move it to a different position in the screen arrangement?
3. Can you try with Wayland anyway to see if the issue reproduces there? I'm not suggesting you use it full-time, just for testing purposes.
3a. What's the problem with Eclipse on Wayland? It should be able to run just fine using XWayland, no?
Comment 2 Jeff Beardsley 2024-12-18 20:15:45 UTC
(In reply to Nate Graham from comment #1)
> Some questions:
> 1. What's the make and model of the affected screen?

The screens are all ViewSonic VA2719-2K monitors (bought the same day because I am a bit OCD, they need to look and act the same :)

> 2. Is it always just this screen, even if you move it to a different position in the screen arrangement?

It's not always the same screen.  Usually it's #3 (the right-most).  About 10% of the time it's #2

> 3. Can you try with Wayland anyway to see if the issue reproduces there? I'm not suggesting you use it full-time, just for testing purposes.
I will try
> 3a. What's the problem with Eclipse on Wayland? It should be able to run just fine using XWayland, no?
I will check out XWayland.  If that fixes my Eclipse problem, I'm happy to run full-time on Wayland.
Comment 3 Jeff Beardsley 2024-12-19 09:55:03 UTC
> 3. Can you try with Wayland anyway to see if the issue reproduces there? 

I got running on Wayland yesterday afternoon, and had no problems the rest of the day, into evening.  After sleeping however, the problem occurred upon unlocking.  Exactly as it does in X11.  In this case display #2 (The middle one) went black immediately.

As above, invoking Display Configuration, disabling the affected display and then restoring brought the display back  on.
Comment 4 Nate Graham 2024-12-19 18:39:25 UTC
Might be an issue with identical displays that's being worked on.
Comment 5 Zamundaaa 2025-05-06 17:01:17 UTC
6.3.5 will have a fix for doing modesets when link training is needed, which might be what's (not) happening here. It would at least explain why turning the screen off and then on again fixes the issue.

Once 6.3.5 reaches your distribution, please report back if you can still replicate the issue in a Wayland session
Comment 6 Jeff Beardsley 2025-05-18 19:33:28 UTC
(In reply to Zamundaaa from comment #5)
> 6.3.5 will have a fix for doing modesets when link training is needed, which
> might be what's (not) happening here. It would at least explain why turning
> the screen off and then on again fixes the issue.
> 
> Once 6.3.5 reaches your distribution, please report back if you can still
> replicate the issue in a Wayland session

I've upgraded to Plasma 6.3.5, but the screen blanking issue continues on both X11 and Wayland.
Also there seems to be a new issue, when left for a few hours, the screens may not come back on. (Though i can still log into the machine from another local machine).  That second issue has happened perhaps 3 times this past week.

Operating System: KDE neon 6.3
KDE Plasma Version: 6.3.5
KDE Frameworks Version: 6.14.0
Qt Version: 6.9.0
Kernel Version: 6.11.0-25-generic (64-bit)
Graphics Platform: X11 (Also Wayland)
Processors: 32 × AMD Ryzen 9 7950X 16-Core Processor
Memory: 46.7 GiB of RAM
Graphics Processor 1: AMD Radeon RX 6600
Graphics Processor 2: AMD Radeon Graphics
Manufacturer: ASUS
Comment 7 TraceyC 2025-05-19 19:05:48 UTC
This is happening on my Plasma 6.3.5 system as well, in fact just a little while ago when I unlocked the system after lunch.
Comment 8 Zamundaaa 2025-05-23 15:03:14 UTC
If it happens on X11 too, and the link re-training doesn't fix it on Wayland, then I'm certain this isn't something KWin is causing (or could fix).

Let's collect some more information about it, and then the best course of action will be to pass it along to graphics driver developers. When a display doesn't turn on, please get the output of
> drm_info
> journalctl --user-unit plasma-kwin_wayland --boot 0
and
> sudo dmesg
and attach them here (as files)
Comment 9 Jeff Beardsley 2025-05-23 21:44:47 UTC
Created attachment 181693 [details]
jbeard-dmesg-output
Comment 10 Jeff Beardsley 2025-05-23 21:46:27 UTC
(In reply to Jeff Beardsley from comment #9)
> Created attachment 181693 [details]
> jbeard-dmesg-output

So I set my WM back to Wayland and left it alone for 10 minutes.  Didn't get the original problem, but rather the second issue I mentioned: All screens off, no interaction seems to work.  I did log into the box over my local network and ran the suggested utilities before rebooting.

Interestingly, drm_info had a permission issue: (though normally this works fine)
/dev/dri/card0: Permission denied
Failed to retrieve information from /dev/dri/card0

"journalctl --user-unit plasma-kwin_wayland --boot 0" did not return anything

I'll attach my dmesg output as jbeard-dmesg-output
Comment 11 Jeff Beardsley 2025-05-23 22:06:52 UTC
Created attachment 181695 [details]
jbeard-drm-info
Comment 12 Jeff Beardsley 2025-05-25 23:34:08 UTC
(In reply to Zamundaaa from comment #8)
> If it happens on X11 too, and the link re-training doesn't fix it on
> Wayland, then I'm certain this isn't something KWin is causing (or could
> fix).
> 
> Let's collect some more information about it, and then the best course of
> action will be to pass it along to graphics driver developers. When a
> display doesn't turn on, please get the output of
> > drm_info
> > journalctl --user-unit plasma-kwin_wayland --boot 0
> and
> > sudo dmesg
> and attach them here (as files)

Ok, now I have just seen the original problem occur on X11.
adding three files:
   jbeard-497632-x11-dmesg
   jbeard-497632-x11-drm-info
   jbeard-497632-x11-kwin-journal
Comment 13 Jeff Beardsley 2025-05-25 23:36:31 UTC
Created attachment 181745 [details]
drm_info for x11 occurrence of the reported issue
Comment 14 Jeff Beardsley 2025-05-25 23:37:20 UTC
Created attachment 181746 [details]
kwin-journal for x11 occurrence of the reported issue
Comment 15 Jeff Beardsley 2025-05-25 23:37:52 UTC
Created attachment 181747 [details]
dmesg for x11 occurrence of the reported issue
Comment 16 Jeff Beardsley 2025-05-25 23:38:45 UTC
(In reply to Jeff Beardsley from comment #12)
> (In reply to Zamundaaa from comment #8)
> > If it happens on X11 too, and the link re-training doesn't fix it on
> > Wayland, then I'm certain this isn't something KWin is causing (or could
> > fix).
> > 
> > Let's collect some more information about it, and then the best course of
> > action will be to pass it along to graphics driver developers. When a
> > display doesn't turn on, please get the output of
> > > drm_info
> > > journalctl --user-unit plasma-kwin_wayland --boot 0
> > and
> > > sudo dmesg
> > and attach them here (as files)
> 
> Ok, now I have just seen the original problem occur on X11.
> adding three files:
>    jbeard-497632-x11-dmesg
>    jbeard-497632-x11-drm-info
>    jbeard-497632-x11-kwin-journal

will also now switch over to Wayland to catch it there
Comment 17 Zamundaaa 2025-05-26 13:18:43 UTC
hmm, nothing useful in dmesg. drm_info shows though that the driver has been told to turn the screens on, so you can definitely report this at https://gitlab.freedesktop.org/drm/amd/-/issues (attach the dmesg and drm_info outputs there too)