SUMMARY Prior to Plasma 6, there was no support for Presentation Time, so Chromium and other apps relying on the protocolon Wayland outright failed to v-sync, and ran at an arbitrary frame rate around 60 FPS. Tested with https://vsynctester.com on Chromium Wayland: Now that Plasma 6 has support for Presentation Time, Chromium succeeds to get v-sync on my 120Hz screen, but not on my 240Hz screen. On my 240Hz screen, it goes up to about 120 FPS and "searches" for v-sync around that value. Tested with weston-presentation-shm, p2p is shown as about 8300 us -> dividing 1000 with 8.3 ms gives 120. STEPS TO REPRODUCE - Chromium: start with --ozone-platform=wayland, visit https://vsynctester.com. - weston-presentation-shm: run, then look at p2p value. OBSERVED RESULT - Chromium does not go above about 120 FPS on 120+ FPS screens. (I tested with 240Hz) - weston-presentation-shm only occasionally throws a p2p value around 4170 us (eyeing it, looks like about 10%) EXPECTED RESULT - Chromium syncs up to monitor refresh rate, not just up to 120 FPS. - weston-presentation-shm outputs p2p values corresponding to monitor refresh rate (1000 / 240 should be around 4170 us) SOFTWARE/OS VERSIONS Operating System: EndeavourOS KDE Plasma Version: 6.0.1 KDE Frameworks Version: 6.0.0 Qt Version: 6.6.2 Kernel Version: 6.7.8-arch1-1 (64-bit) Graphics Platform: Wayland
Important, the issue is non-reproducible if using a screen with a refresh rate under or equal to 120 Hz.
Testing further (laptop with 120Hz screen): The amount and frequency of 'incorrect' p2p values (double the time it should take to present a frame on a display of a specified refresh rate) that weston-presentation-shm shows increases drastically when actively running Chromium displaying the https://vsynctester.com website.
Sounds like KWin is dropping frames. What CPU and GPU is this on?
It's a Ryzen 7 4800H laptop with integrated Radeon Graphics and dedicated Nvidia Graphics (1660Ti). Kwin is running on the integrated Radeon Graphics, of course
It's definitely not an underpowered system, so I suggest attempting to reproduce this issue on your end as well
I didn't mean to imply the problem was on your side, I only needed to know what kind of problem we're talking about. KWin dropping frames on older Intel iGPUs is one thing (and being worked on) but it dropping frames on a Ryzen is new.
Of course, and the issue might still be on my side anyway, who knows :) I only have this laptop to test on.
Hello, this still seems to be an issue as of kwin 6.0.2.
Hello, is there any update on this issue? It is present in 6.0.3 also. Thank you
Plasma 6.1 contains a bunch of performance and frame timing improvements, which might fix this. Please retest this once 6.1 is out
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I will test this again once 6.1 is released on Arch. Currently that is not the case
I can confirm this now works perfectly on kwin 6.1.0!! Both weston-presentation-shm and Chromium now correctly sync up to 240Hz (the highest I can test).
Nope. Nevermind. It's not solved. But I've also figured out what this bug is actually related to. Here's what I found: seems like just *having the proprietary nvidia driver loaded* breaks Chromium vsync on 240Hz, despite Kwin running on my AMD GPU. The only reason I thought it was fixed was that I forgot that I was in the middle of switching to beta nvidia drivers, and I didn't finish it. So when I loaded up my system, it wasn't loaded, and I just so happened to have installed plasma 6.1 at the same time. I'll create a new bug report.