CODEWITHSUNDEEP
linux3dglx
mschmoock
mschmoock

Reputation: 20854

Disable vertical sync for glxgears

Sometimes you need to check whether you Linux 3D acceleration is really working (besides the glxinfo output). This can be quickly done by the glxgears tool. However, the FPS are often limited to the displays vertical refresh rate (i.e. 60 fps). So the tool becomes more or less useless since even a software render can produce 60FPS glxgears easily on modern CPUs.

I found it rather hard to get a quick and easy solution for this, I answer my own question. Hopefully it saves your time.

Upvotes: 114

Views: 166415

Answers (8)

Kayla
Kayla

Reputation: 1

There's a Sync to VBlank setting within nvidia-settings. This locks it to vsync as well. turning that off fixes it. got me 29k on a gtx 1660s

Upvotes: 0

Krellan
Krellan

Reputation: 501

Putting the other answers all together, here's a command line that will work:

env vblank_mode=0 __GL_SYNC_TO_VBLANK=0 glxgears

This has the advantages of working for both Mesa and NVidia drivers, and not requiring any changes to configuration files.

Upvotes: 26

olmerg
olmerg

Reputation: 435

I found a solution that works in the intel card and in the nvidia card using Bumblebee.

> export vblank_mode=0
glxgears
...
optirun glxgears
...
export vblank_mode=1

Upvotes: 5

ali_m
ali_m

Reputation: 74154

If you're using the NVIDIA closed-source drivers you can vary the vertical sync mode on the fly using the __GL_SYNC_TO_VBLANK environment variable:

~$ __GL_SYNC_TO_VBLANK=1 glxgears
Running synchronized to the vertical refresh.  The framerate should be
approximately the same as the monitor refresh rate.
299 frames in 5.0 seconds = 59.631 FPS

~$ __GL_SYNC_TO_VBLANK=0 glxgears
123259 frames in 5.0 seconds = 24651.678 FPS

This works for me on Ubuntu 14.04 using the 346.46 NVIDIA drivers.

Upvotes: 113

Kevin
Kevin

Reputation: 2929

For intel drivers, there is also this method

Disable Vertical Synchronization (VSYNC)

The intel-driver uses Triple Buffering for vertical synchronization, this allows for full performance and avoids tearing. To turn vertical synchronization off (e.g. for benchmarking) use this .drirc in your home directory:

<device screen="0" driver="dri2">
    <application name="Default">
        <option name="vblank_mode" value="0"/>
    </application>
</device>

Upvotes: 2

nocnokneo
nocnokneo

Reputation: 1967

For Intel graphics and AMD/ATI opensource graphics drivers

Find the "Device" section of /etc/X11/xorg.conf which contains one of the following directives:

  • Driver "intel"
  • Driver "radeon"
  • Driver "fglrx"

And add the following line to that section:

Option     "SwapbuffersWait"       "false"

And run your application with vblank_mode environment variable set to 0:

$ vblank_mode=0 glxgears

For Nvidia graphics with the proprietary Nvidia driver

$ echo "0/SyncToVBlank=0" >> ~/.nvidia-settings-rc

The same change can be made in the nvidia-settings GUI by unchecking the option at X Screen 0 / OpenGL Settings / Sync to VBlank. Or, if you'd like to just test the setting without modifying your ~/.nvidia-settings-rc file you can do something like:

$ nvidia-settings --load-config-only --assign="SyncToVBlank=0"  # disable vertical sync
$ glxgears  # test it out
$ nvidia-settings --load-config-only  # restore your original vertical sync setting

Upvotes: 31

neutro
neutro

Reputation: 71

Disabling the Sync to VBlank checkbox in nvidia-settings (OpenGL Settings tab) does the trick for me.

Upvotes: 7

mschmoock
mschmoock

Reputation: 20854

The vblank_mode environment variable does the trick. You should then get several hundreds FPS on modern hardware. And you are now able to compare the results with others.

$>   vblank_mode=0 glxgears

Upvotes: 155

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