KWin-LowLatency: An Effort To Yield Less Stutter & Lower Latency With The KDE Desktop

[aufkrawall]

Holly shet, finally! Finnaly someone will make something about this problems on Kwin. I already reported in another thread about my experience with Plasma on AMD GPU. Kwin needs a rework urgently!

Too bad KWin on Xorg was declared legacy before it was neither finished nor fixed. Poor management of priorities of what's important.

[fuzz]

Too bad KWin on Xorg was declared legacy before it was neither finished nor fixed.

Really? Because KWin on wayland is completely broken for the majority of users, as far as I can tell.

[aufkrawall]

Really? Because KWin on wayland is completely broken for the majority of users, as far as I can tell.

But at least the Wayland version doesn't introduce stutter, unlike the X11 one. They haven't fixed it in years and it still doesn't look like it.
Their rejection of auto-unredirect for fullscreen is pathetic too, like if I would always want to manually switch compositing on and off when alt + tabbing while gaming...

[oiaohm]

Really? Because KWin on wayland is completely broken for the majority of users, as far as I can tell.

https://www.youtube.com/watch?v=FYItn1jvkbI

Really not as broken as you would first presume. KWin on wayland has some very interesting new testing features. Like this one where you can test for multi display output with a single display.

[RealNC]

Strange, here works fine. What is exactly the problem? What is your setup? I use a AMD card with radeonsi driver, VLC video player and KDE to watch F1 races on my PC (using a PixelView USB adapter), but here is a 60Hz broadcast and I use a 120Hz Benq monitor.

The problem is heavy stutter. KWin is unable to sync every frame perfectly. 60FPS videos at 120Hz also have the problem, of course. Kwin constantly "hiccups" every 2 or 3 seconds, dropping frames.

NVidia driver on a 165Hz display. (I only use 120Hz or 100Hz for the desktop, depending on whether I watch 24/30/60FPS video (movies, NTSC) or 25/50FPS (PAL) video. The attitude of the kwin developers is the usual "the human eye can't see more than blah blah frames per second" or "nobody needs a display with more than 60Hz" nonsense.

[shmerl]

https://www.youtube.com/watch?v=FYItn1jvkbI

Really not as broken as you would first presume. KWin on wayland has some very interesting new testing features. Like this one where you can test for multi display output with a single display.

It's far from ready due to stuff like this: https://bugs.kde.org/show_bug.cgi?id=387313

So deprecating X11 path before Wayland path is in production quality state is bizarre. And adaptive sync situation is even worse, due to Wayland protocol itself missing features:

https://bugs.kde.org/show_bug.cgi?id=405912
https://gitlab.freedesktop.org/wayla...land/issues/84
https://github.com/swaywm/wlroots/issues/1406

I'm KDE user, and would like to switch to Wayland, but it's just not ready yet. And it seems it will still take years to get to a modern Wayland + Vulkan compositing.

See also: https://github.com/swaywm/wlroots/pull/1214

[Vistaus]

https://www.youtube.com/watch?v=FYItn1jvkbI

Really not as broken as you would first presume.

As long as it still crashes when doing simple tasks on modern Intel-only hardware (as is the case for my setup!), it's broken.

[fuzz]

https://www.youtube.com/watch?v=FYItn1jvkbI

Really not as broken as you would first presume. KWin on wayland has some very interesting new testing features. Like this one where you can test for multi display output with a single display.

It's 100% unusable for me. The bugs have been documented as far as I can tell. Theoretical use cases don't mean something works well. Not blaming anyone, it's just how software development goes.

[Ironmask]

Wayland will always be useless for gaming so long as they keep forcing Vsync, with no way to disable it.

The fact that Wayland and Gnome developers thought it would be okay to force Vsync and even hard cap the refresh rate to 60Hz (only recently fixed in Gnome), makes me have almost zero trust in them for gaming performance.

But Windows (the compositor, DWM.EXE) forces Vsync on all windows. It seems to work fine there.

I agree being able to disable it would be nice, but I don't think it's as big of a detriment as you think.

[Guest]

What exactly is resulting in the stuttering? My crappy i3 Haswell laptop with integrated graphics works very smoothly with kwin+Wayland, even with the compositing effects and high CPU load. Although I don't think a Vulkan compositor needs to be a high priority, I do think it's a better idea than whatever else they intend to do to improve latency.


Speak for yourself. Even though my gaming PC uses X11, I deliberately keep vsync on because I prefer a tear-free experience over input latency. Sure, a hard cap of 60Hz is dumb (assuming your display goes higher) and I agree there should be a [user-friendly] way to disable vsync, but you are heavily exaggerating your preferences as though they're what everyone else prefers.

For me, it's even easier. I don't need to enable vsync everywhere, if there's some software where I prefer no tearing, I just set VBLANK_MODE to the desired value when I'm starting it. In practice, that means only the web browser, as smooth scrolling looks bad with (low refresh rate) tearing. At higher refresh rates vsync becomes irrelevant, because of how hard it is to notice torn frames.