Created attachment 178276 [details] Screenshot of window border shadows. STEPS TO REPRODUCE 1. Set color accuracy to "Prefer efficiency" 2. Move a window with shadows around borders. OBSERVED RESULT Weird dotted artifacts. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Arch Linux KDE Plasma Version: 6.3.0 KDE Frameworks Version: 6.10.0 Qt Version: 6.8.2 ADDICTIONAL INFORMATION Other than the dotted artifacts on shadows when moving windows with the preferred efficiency setting that was not there during the 6.3 beta. Now the prefer efficiency setting does not yield the same performance improvement it did in the 6.3 beta; it's slightly less efficient now on 6.3.0 stable, it's quite noticeable. This has to be a regression or something somewhere because during the beta I used this setting the entire time experienced literally no frame drops, but now I am.
It was an amazing improvement over my laggy experience with ICC profiles compared to what I got in earlier plasma versions, but it only lasted for the beta period; hopefully it's not a huge deal to fix.
Please attach the output of drm_info, once for when you're using "prefer efficiency" and once for "prefer color accuracy". The only commit that *might* be relevant for this is https://invent.kde.org/plasma/kwin/-/commit/888deff8c65dd46bf6df9d00fb8022bc1779f793, and it could be a simple case of taking into account potential rounding errors. Could you test a patch to check if it's actually the case?
Also, please attach the ICC profile you're using, maybe I can trigger the bug on my PC with it too
Created attachment 178312 [details] MyICC By the way, a 1080p video in MPV now shows about 50% render usage with the prefer efficiency setting; if I exit and enter fullscreen, it spikes to 60%. I should have taken a screenshot in the beta, but I'm pretty sure it was only using 25% then.
Actually, now that I compare, prefer accuracy and prefer efficiency; they are now closer to using the exact same render usage, which they weren't previously, because prefer accuracy uses 55% render with the 1080p video and prefer efficiency now uses about 50%. This definitely shouldn't be the case; from what I've seen before, the prefer efficiency setting should significantly reduce render usage compared to the prefer color accuracy setting, so this as well shows that the prefer efficiency setting is indeed way less efficient now than before. It's now almost the same performance drop as the prefer accuracy setting.
I can't see any glitches, but I can confirm that the ICC profile causes a shadow buffer to be used.
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/7147
Created attachment 178316 [details] Dots Here's a screen recording of the dots that appear.
By the way, these dots are even more noticeable on a lower resolution display because I have a laptop with a 1366x768 screen, and I see it even more clearly. I also had the Plasma 6.3 beta on the laptop with the ICC profile set, and the dots were not there, so it was deffinitely something that changed release of 6.3.0 that's causing it.
Do you remember if you used "prefer efficiency" or "prefer color accuracy" in the beta? I have absolutely no explanation to how KWin could cause these dots with its actual rendering. We've seen really weird bugs with rarely used buffer formats before though, so it could be a driver bug with 16 bits per color formats (which gets used with "prefer color accuracy"). If you set https://invent.kde.org/plasma/kwin/-/wikis/Environment-Variables#kwin_drm_use_modifiers to 0, do the dots go away?
Yes, I'm 100% sure I used the prefer efficiency setting, and it was not happening during the beta; it's happening on 2 laptops. My gaming laptop has a 1080p display, and my other laptop has a 1366x768 display. The 1366 display laptop's CPU is an Intel Ivy Bridge CPU, and the gaming laptop is an i5 Kaby Lake CPU. It does not happen with the prefer accuracy setting, though, but it definitely was not happening with the prefer efficiency setting previously. I'd have noticed it; it's pretty easy to notice without even zooming in.
And the environment variable doesn't change anything still the same.
Git commit 582ec868123f328eb83d03b2a6b59175d948808c by Xaver Hugl. Committed on 14/02/2025 at 12:33. Pushed by zamundaaa into branch 'master'. backends/drm: be a little bit less strict about range checking Rounding errors in floating point calculations can otherwise wrongly trigger the check and prevent KMS offloading for no reason M +2 -1 src/backends/drm/drm_colorop.cpp https://invent.kde.org/plasma/kwin/-/commit/582ec868123f328eb83d03b2a6b59175d948808c
*** Bug 500021 has been marked as a duplicate of this bug. ***
Git commit 7d9528edc46fcb4c49c853af5b95fc62d7b2c1ba by Xaver Hugl. Committed on 14/02/2025 at 13:13. Pushed by zamundaaa into branch 'Plasma/6.3'. backends/drm: be a little bit less strict about range checking Rounding errors in floating point calculations can otherwise wrongly trigger the check and prevent KMS offloading for no reason (cherry picked from commit 582ec868123f328eb83d03b2a6b59175d948808c) Co-authored-by: Xaver Hugl <xaver.hugl@gmail.com> M +2 -1 src/backends/drm/drm_colorop.cpp https://invent.kde.org/plasma/kwin/-/commit/7d9528edc46fcb4c49c853af5b95fc62d7b2c1ba
Ok, this is marked as resolved, but I'm just going to add this information: I did a partial downgrade of KWin alone back to 6.2.91, which is the Plasma 6.3 beta version of KWin, the performance issues of the efficiency setting, and the weird dotted artifacts stopped happening. I forgot I didn't clear my pacman cache yet, so I was able to downgrade and do a quick test, seeing that this fixed the issues it 100%, guarantees that it's something odd in the latest version of Kwin 6.3.0.
*** Bug 500058 has been marked as a duplicate of this bug. ***
*** Bug 499962 has been marked as a duplicate of this bug. ***
Ok, as of the 6.3.1 release, the artifacting issue is also gone, and performance is back to how it was in the beta.