The freeze fix commit causes high CPU load and high latency increase about kwin-lowlatency

[realnc]

I haven't had the chance to thank you for this project yet. It fixed all my issues with video playback in KDE (using MPV as the video player.) No matter what I did previously, I would get some skips/hiccups when watching videos. It was really obnoxious. So I constantly had to disable compositing and switch my monitor to 24Hz or 60Hz or 50Hz, depending on the FPS of the video what I'm watching. It was a constant hassle. With this version of kwin, it's totally fine at 120Hz or 100Hz with compositing enabled, just like under MS Windows.

(I just upgraded to Plasma 5.16 just now, and the Plasma/5.16 branch doesn't compile. But I'll open a new bug about that one.)

[tildearrow]

This means NVIDIA doesn't wait for VBlank when glFinish is called... I'll add some NVIDIA-specific code to use the old method.

[tildearrow]

I have one question though: are you upgrading to 5.16? I'll push a fix to both versions but I'd prefer to know where to begin first.

[realnc]

I'll hold off the 5.16 upgrade in order to test the fix on 5.15 too.

[tildearrow]

Please test the latest commit. I've added the old waitSync code back.

[realnc]

Just tested and it fixes the issue.

[tildearrow]

Good to hear! I will be releasing 5.15.6-2 and 5.16.0-2 with the fix soon.

[tildearrow]

Thank you for the feedback. It is great to know it works well on your system.

(is it due to some EGL header missing? if so, try recreating the build directory. It has occurred to me a few times.)

[realnc]

No, it's something else. Building your repo directly works. But generating the patch and applying it to vanilla kwin 5.16 and letting portage apply and build results in:

/usr/lib/gcc/x86_64-pc-linux-gnu/9.1.0/../../../../x86_64-pc-linux-gnu/bin/ld: effects/CMakeFiles/kwin4_effect_builtins.dir/effect_builtins.cpp.o: in function `KWin::Effect* KWin::BuiltInEffects::createHelper<KWin::MousePosEffect>()':
effect_builtins.cpp:(.text._ZN4KWin14BuiltInEffects12createHelperINS_14MousePosEffectEEEPNS_6EffectEv[_ZN4KWin14BuiltInEffects12createHelperINS_14MousePosEffectEEEPNS_6EffectEv]+0x13): undefined reference to `KWin::MousePosEffect::MousePosEffect()'
collect2: error: ld returned 1 exit status

I'm investigating and trying to reproduce when building your sources. Maybe it's a compiler flag or USE lag combination.

[tildearrow]

Good morning. Can you please try 5.16.5 to ensure it doesn't bring this bug back?

[realnc]

Good morning. Can you please try 5.16.5 to ensure it doesn't bring this bug back?

No 100% CPU load, but I think there's some lag increase (distance between cursor and window when moving it around.)

[tildearrow]

...are you still using the 430.14 driver?

[realnc]

Nope. 435.21.

Could be placebo. I'll need to downgrade kwin again and compare.

[tildearrow]

It's been almost 2 months... Hoping that it has been fixed by now.