My Lenovo G27q-20, which is a Gsync compatible certified device, has a VRR range of 48-165Hz. When frame rate drops below 48fps, there is a noticeable stutter event happening. I can reproduce this in Strange Brigade native Vulkan (Proton) by increasing render resolution scale to 200%, so I can drop below 48fps in some scenes with my RTX 3060.
On Windows, this transition is seamless, i.e. there is no noticeable stutter event. MangoHUD frame time graph shows flat line for frame render times, so the stutter apparently happens at VRR presentation stage. Maybe it’s related to frame doubling, that is required to make LFC transition seamless (see old pcper Gsync/VRR reviews). It doesn’t matter if vsync is enabled or not. KWin compositor of the Xorg session is manually suspended so it’s guaranteed not to interfere.
Has been happening for many months and drivers, maybe it never worked right. Just confirmed the issue again with driver 515.43.04 on Arch Linux 5.18.
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@aufkrawall
Can you please try once with Latest Production Branch Version 515.48.07.
If issue still persists, please share nvidia bug report and repro video for reference.
515.48.07 still shows the issue.
How I can reproduce the issue in Strange Brigade:
Note that the issue itself can’t be captured on a video, and also capturing the screen with an external camera probably wouldn’t really work. It’s not a very hard stuttering, but is very annoying regardless, as it happens repeatedly when fps are close to the lower VRR range limit.
nvidia-bug-report.sh log file:
nvidia-bug-report.tar.gz (792.9 KB)
Btw: I’ve noticed that VRR with the open source Nvidia kernel driver is not just missing for Wayland, but also Xorg. It doesn’t show up in nvidia-settings and isn’t used.
VRR LFC is still broken in 570.86.16 driver on RTX 3060 (and presumably any other Nvidia GPU).
Strange Brigade Windows 36fps: Monitor runs at stable 72Hz and result is smooth and doesn’t flicker.
Linux 36fps (both Xorg and Wayland, both proprietary and open Nvidia kernel module): Monitor refresh rate is all over the place between 50Hz and 144Hz, causing stutter and flicker. Frame time graph is flat/good when this is happening, and the actual result on screen looks normal/smooth once I get more than 48fps (VRR range minimum) and monitor is stable at e.g. 52fps/Hz.
Oh so it’s not just me. I notice this same behaviour on my RTX 3060 Ti.
On Windows LFC is perfect, on Linux it basically just doesn’t work. I’m also on driver 570, but even when I was on 565, 560, 550 and 545, the issue was still present.
Xorg or Wayland, doesn’t matter. Exact same symptoms as you described on my end.
Amazing how this was never fixed in 3 years.
Thank you for bringing this thread back up, it was long forgotten and I never came across it, hopefully Nvidia will eventually fix this.
Yeah. Also, the Windows driver recently has received an improvement for VRR LFC. The Nvidia Linux devs really should take a look at how the Windows driver does it.
@amrits Any update on forwarding this to the driver devs?
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