Acer GN246HL - Troubles with Linux

[jigoku]

Hello. I recently purchased an "Acer GN246HL". It supports up to 144hz, lightboost, and i believe it is a TN LED monitor.

I have tried this monitor on various Linux distributions, from Slackware to Linux Mint, and have a repeating problem relating to ghosting/blur. This visual effect is present even whilst slowly scrolling a webpage in firefox, text becomes "double-visioned" -- if that makes sense.

I have also tested this monitor on a windows machine, following the guides on here about over riding the monitor model/edid in order to set custom modes, which enables lightboost. Now under windows 10, on the 120hz lightboost mode, the image is crystal clear with absolutely no blur. I can shake/move firefox rapidly, and text is sharp and readable whilst doing this.

Now the problem i am getting on Linux with this monitor... I came across this:
http://forums3.armagetronad.net/viewtop ... =1&t=23173

Mentioning to create custom modelines, and override the EDID/default modes. This does allow lightboost to work, as my LED on the monitors power switch turns green, and the lightboost OSD is then available to adjust the brightness of the strobing.

Here is my xorg.conf;

Code: Select all

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    Option         "Xinerama" "0"
EndSection

Section "Files"
    FontPath        "/usr/lib64/X11/fonts/misc/:unscaled"
    FontPath        "/usr/lib64/X11/fonts/100dpi/:unscaled"
    FontPath        "/usr/lib64/X11/fonts/75dpi/:unscaled"
    FontPath        "/usr/lib64/X11/fonts/misc/"
    FontPath        "/usr/lib64/X11/fonts/Type1/"
    FontPath        "/usr/lib64/X11/fonts/Speedo/"
    FontPath        "/usr/lib64/X11/fonts/100dpi/"
    FontPath        "/usr/lib64/X11/fonts/75dpi/"
    FontPath        "/usr/lib64/X11/fonts/cyrillic/"
    FontPath        "/usr/lib64/X11/fonts/TTF/"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Acer GN246HL"
    HorizSync       30.0 - 160.0
    VertRefresh     56.0 - 144.0
    Option         "DPMS"

    # lightboost related modelines as mentioned at: http://forums3.armagetronad.net/viewtopic.php?f=1&t=23173
    Modeline "1920x1080_120lb" 286.7 1920 1968 2000 2080 1080 1083 1088 1149 +HSync -VSync
    Modeline "1920x1080_100lb" 235.50 1920 1968 2000 2080 1080 1083 1088 1138 +HSync -VSync
    Modeline "1920x1080_144" 317.49  1920 1944 1975 2008  1080 1083 1088 1098 +HSync -VSync
    Modeline "1920x1080_60"  148.50  1920 2008 2052 2220  1080 1084 1089 1125 +HSync +VSync

EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce GTX 1060 3GB"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "Stereo" "0"
    Option         "nvidiaXineramaInfoOrder" "DVI-D-0"
    Option         "SLI" "Off"
    Option         "MultiGPU" "Off"
    Option         "BaseMosaic" "Off"

    # Help eliminate Linux tearing by forcing this:
    Option         "TripleBuffer" "On"
    Option         "AllowIndirectGLXProtocol" "Off"
    Option         "metamodes" "1920x1080_120lb +0+0 { ForceFullCompositionPipeline = On }"

    # Override modes
    Option "ModeValidation" "DVI-D-0: NoEdidModes, NoXServerModes, NoVesaModes, AllowNonEdidModes"

    SubSection     "Display"
        Depth       24
	Modes "1920x1080_144"
	Modes "1920x1080_120lb"
	Modes "1920x1080_100lb"
	Modes "1920x1080_60"
    EndSubSection
EndSection

The main point of interest is:

Code: Select all

Modeline "1920x1080_120lb" 286.7 1920 1968 2000 2080 1080 1083 1088 1149 +HSync -VSync

How do i know if this is correct for this monitor? The examples from the linked thread above reference a different brand/model... however the pixel clock is the same as when enabling 120hz lightboost on windows (which doesn't cause blur).

How can i solve this problem? I am using nvidia's latest short term driver, 396.24. I have also tried other driver versions, different xserver versions, different kernels, etc... but i still get the same "ghosting" which shouldn't be there.

There doesn't seem to be a lot of information about this in relation to Linux, and i feel this has to be the best place to ask online about all of this. Could anyone help me out here? I haven't the slightest clue where to start looking at what is causing this problem.

The one thing i am certain of, is that the monitor is not faulty, due to lightboost/120hz working as it should under Win10. Seem's to be related to something on Linux, possibly even something going wrong in nvidia's driver.

[RealNC]

If you're using an nvidia GPU, you can use CRU to edit your EDID, export it to a bin file, then use that in Linux. In your nvidia X11 configuation file (like /etc/X11/xorg.conf.d/nvidia.conf), in the "Device" section, you need:

Option "CustomEDID" "DFP-2:/etc/X11/EDID.bin"

Use the correct ID instead of "DFP-2" and change the file path to wherever you saved the bin file.

[jigoku]

If you're using an nvidia GPU, you can use CRU to edit your EDID, export it to a bin file, then use that in Linux. In your nvidia X11 configuation file (like /etc/X11/xorg.conf.d/nvidia.conf), in the "Device" section, you need:

Option "CustomEDID" "DFP-2:/etc/X11/EDID.bin"

Use the correct ID instead of "DFP-2" and change the file path to wherever you saved the bin file.

Ok, followed your advice, and now have /etc/X11/xorg.conf.d/10-nvidia.conf (removed my xorg.conf)

Code: Select all

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "metamodes" "1920x1080_120 +0+0 { ForceFullCompositionPipeline = On }" 
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName	   "GeForce GTX 1060 3GB"
    Option         "CustomEDID" "DVI-D-0:/etc/X11/EDID.bin"
EndSection

There seems to be a slight overall improvement, but the ghosting/trails of any scrolling text is still present under Linux. The unfortunate thing is, with the ghosting test: https://www.testufo.com/ghosting , this doesn't actually work on Linux for some reason (says vsync is not supported?), so it's hard to get a side by side comparison compared to Windows.

EDIT:
I also initially had

Code: Select all

    Option         "TripleBuffer" "on" 
    Option         "AllowIndirectGLXProtocol" "off" 

In my xorg.conf, as i had read this performs better with the ForceFullCompositionPipeline settings, however, disabling TripleBuffer now makes things more smoother, but still the problem of ghosting is still present, albeit not as much of a problem as before.

ForceFullCompositionPipeline seems to be required, due to tearing issues (nvidia bug that's been around for years), and disabling that only makes the actual picture quality worse for moving objects. Do you know if there are any other settings worth trying, that may help with all of this?

[RealNC]

The ghosting seems to be the result of Linux browsers not supporting high Hz/FPS. Chrome, Firefox and Opera are limited to 60FPS. This looks like ghosting.

As for the desktop, Gnome doesn't work well at all with >60Hz. Neither does XFCE. The only desktop that does run at 120FPS or higher is KDE, and for it to work it needs an edit in ~/.config/kwinrc.

In general, >60Hz displays are a very, very, VERY low priority for the people working on Linux desktops and browsers. (In fact they sometimes mock people who ask about it. The human eye can't see past 24FPS and all that.)

I tried the three well-known Linux desktops (Gnome, KDE, XFCE), and KDE is the only one that works with high refresh displays. It has issues with NVidia drivers (which will not be fixed any time soon; KDE wants NVidia to fix them, which won't happen,) but overall it's mostly OK.

[jigoku]

As for the desktop, Gnome doesn't work well at all with >60Hz. Neither does XFCE. The only desktop that does run at 120FPS or higher is KDE, and for it to work it needs an edit in ~/.config/kwinrc.

In general, >60Hz displays are a very, very, VERY low priority for the people working on Linux desktops and browsers. (In fact they sometimes mock people who ask about it. The human eye can't see past 24FPS and all that.)

On Linux i generally use the Awesome window manager, along with xcompmgr for compositing, but despite also trying KDE4, KDE5, XFCE4, twm, fluxbox etc with a whole range of different compositors, the screen behaves the same no matter what the environment.

What would you think is responsible for this problem? As in, the problem is not present on Windows, in fact with 120hz lightboost, i've never seen such a crystal clear and sharp image on a monitor before, especially whilst moving windows about the desktop, or playing first person shooters.

I would guess myself, that something in X11, or the nvidia-driver is responsible... i haven't seen any information online about the GN246HL and people using Linux, so i feel like i've exhausted any possible solutions already.

What would anyone recommend trying next?

[RealNC]

KDE with the kwinrc tweak is the only desktop that works for me. XFCE in particular does not offer a way to unlock its frame rate, and Gnome can't render frames fast enough, which leads to a lot of severe frame skipping when you open a window or two.

For KDE to work though, you need this in your ~/.config/kwinrc:

Code: Select all

[Compositing]
MaxFPS=150
RefreshRate=150

The value you use has to be well above your refresh rate, otherwise there's stutter.

As for what the core problem is: it's because none of the Linux desktops seem to synchronize to vsync. They do have tearing prevention, but that's just standard OpenGL vsync. They do not actually sync their compositor to vsync, like Windows and macOS do.

This might be changing with the move from X11 to Wayland, but it's not really there yet, at least with NVidia drivers. KDE does not support Wayland when using NVidia's drivers. (And they have stated multiple times that they refuse to support it. KDE is on very bad terms with NVidia in general, because NVidia doesn't show much interest in being compatible with the Linux graphics stack, and especially KDE.)

[jigoku]

KDE with the kwinrc tweak is the only desktop that works for me. XFCE in particular does not offer a way to unlock its frame rate, and Gnome can't render frames fast enough, which leads to a lot of severe frame skipping when you open a window or two.

For KDE to work though, you need this in your ~/.config/kwinrc:

Code: Select all

[Compositing]
MaxFPS=150
RefreshRate=150

The value you use has to be well above your refresh rate, otherwise there's stutter.

As for what the core problem is: it's because none of the Linux desktops seem to synchronize to vsync. They do have tearing prevention, but that's just standard OpenGL vsync. They do not actually sync their compositor to vsync, like Windows and macOS do.

This might be changing with the move from X11 to Wayland, but it's not really there yet, at least with NVidia drivers. KDE does not support Wayland when using NVidia's drivers. (And they have stated multiple times that they refuse to support it. KDE is on very bad terms with NVidia in general, because NVidia doesn't show much interest in being compatible with the Linux graphics stack, and especially KDE.)

I really wish i had went and purchased an amd gpu now!

Thanks so much for that information. Loaded up KDE5 with your recommendation for compositing... now the window manager itself is actually rendering windows just as smoothly as on Windows! Interesting thing however, the blurred/double-vision text is still present when scrolling a webpage in firefox.... but if i drag the firefox window around, the text is very sharp and has absolutely no ghosting. I wonder if that's something related to GTK? Either way, this is a massive improvement, and i guess i will start using KDE as my main desktop again.

Guess we will just have to wait out for nvidia to do something about it.

[RealNC]

Interesting thing however, the blurred/double-vision text is still present when scrolling a webpage in firefox.

As I said earlier, the major browser vendors do not seem to care much about high FPS support on Linux. Firefox, Chrome and Opera only render at 60FPS under Linux, which of course means it's just as blurry as on a 60Hz display.

[Chief Blur Buster]

As Chief Blur Buster, I want to bring attention:

I currently am personally offering a $1000 open source bounty for Linux TestUFO 60Hz fixes (Conditions apply).

[jigoku]

Small update... i've been web searching all day, and came across a setting for firefox that can eliminate motion blur on a 120hz monitor.... (or any monitor higher than 60hz for that matter).

Go to about:config, and enter "layout.frame_rate". Change this to the actual refresh rate of the screen, in my case the value would be 120. This makes firefox able to scroll pages with any motion blur at all! I was literally about to return this monitor, but this now works and is a perfect solution for my use case.

The default value of this setting is -1, which means for firefox to use vsync, but as mentioned here by RealNC, viewtopic.php?f=4&t=4170&p=33312#p33343

There seems to be vsync issues with alot of Linux applications.
Well, i can now happily scroll webpages without any blur in firefox (regardless of window manager) now that this setting has been adjusted.

I also had a look at these:
https://www.testufo.com/
https://www.testufo.com/ghosting
https://www.testufo.com/eyetracking
https://www.testufo.com/persistence

These tests all run perfectly fine without any ghosting/blur/motion problems. Sure the browser is now forced to 120fps. But it certainly gives you the ability to compare results with lightboost related visuals on Windows/Linux.

I guess this is mostly solved? Seem's most of the problem was related to firefox (and other web browsers).

Note that vsync is obviously not supported by the test, but it's now running at 120fps after changing this setting in about:config

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