NVidia eXec - nvx

nvx is a script to run programs on nvidia optimus setups with power management. nvx tries to be extremely simple to install and use, and supports both Xorg and Wayland environments.

Note: This script is highly experimental and require very recent versions of nvidia drivers and gnome patches to work.

Usage

1. run nvx start [program]
2. that is it

The script will require user password to toggle the GPU and modules, but it must not be started with sudo. You might be asked to input your password before the program starts (to initialize the device), and after the program finishes (to cleanup resources).

nvx start may be called multiple times, its is only going to initialize the devices in the first call and clean resources when the last call ends.

All actions

• automatic gpu management:

  • start [command] - Turn on the gpu, load modules if necessary, and run [command]. When [command] exits, the gpu is turned off if there are no other 'nvx start' processes. During turn off, processes using the gpu not started with 'nvx start' are killed.

• manual gpu management:

  • on - Turn on the gpu and load modules. If the gpu is already started, it tries to turn on again it and reload all modules. Effectively, it does nothing.
  • off - Unload modules and turn off the gpu. If the gpu is already off, it tries to turn off again it and unload all modules. Effectively, it does nothing. If there are processes using the gpu, the turn off process might hang indefinitely. Use 'nvx ps' to check with processes are running to finish them. 'nvx kill' can be used as well, but it might not be able to kill all processes.
  • off-boot - Same as 'off', but it does not unload modules.
  • off-kill - Same as 'off', but it also attempts to kill processes using the gpu.
  • status - Print the status of the gpu.
  • ps - Print the processes using the gpu.
  • psx - Print 'nvx start' processes.
  • kill - Attempts to kill all processes using the gpu. These are the same processes reported by 'nvx ps'.
  • dev - Print the pci display devices that contain nvidia cards. Only works if the gpu is on.

Installation

Currently, this package is only available for Arch Linux on the Arch User Repository.

Installing the package the package:

$ git clone https://aur.archlinux.org/nvidia-exec.git
$ cd nvidia-exec
$ makepkg -si
$ ...

You may also install the package using an AUR helper:

$ paru -Sa nvidia-exec
$ ...
$ # or
$ yay -Sa nvidia-exec
$ ...
$ # or whatever helper you might use

After the installation

Once the package is installed, its systemd service must be enabled:

$ sudo systemctl enable nvx

The nvx.service prevents nvidia modules from loading and turn off the graphics card during boot.

It is not necessary to handle files, configurations, PCI buses, etc, all that is done automatically.

Files and Dependencies

For other users that may want to create a package to their preferred systems, the following is where I place the files on Arch Linux.

• nvx -> /usr/bin/nvx - Script that handles the gpu and run programs.
• nvx.service -> /usr/lib/systemd/system/nvx.service - Service that turns off gpu during boot.
• modprobe.conf -> /usr/lib/modprobe.d/nvx.conf - Blacklisted modules.

Required dependencies:

• jq - https://stedolan.github.io/jq/
• lshw - https://linux.die.net/man/1/lshw
• lsof - https://linux.die.net/man/8/lsof
• Nvidia proprietary drivers

Troubleshooting

GPU is still turned on after system boot:

The nvx.service tries to turn off the GPU during the boot process. If there are other services trying to use the GPU at the same time, nvx.service is likely to hang and fail.

Most commonly, that will be caused by NVidia service daemons such as:

• nvidia-persistenced.service
• nvidia-powerd.service

These services can be disabled through systemd (e.g. systemctl disable nvidia-persistenced.service).

Note that the other NVidia services will not run during boot and do not need to be disabled:

• nvidia-hibernate.service
• nvidia-resume.service
• nvidia-suspend.service

GPU turn off process of nvx start [program] hangs:

Hangs due to other processes:

When a program is started using nvx start [program], the GPU is enabled system-wide. Other processes might see that the GPU is enabled and start using the device.

When the program executed using nvx start stops. The script will try to kill all processes using the GPU in order to turn it off. Some programs such as VSCode or Google Chrome might reattach to the device files immediately after their processes using the GPU are killed, preventing the GPU power off.

# kill processes
-- kill process code -> 7397 # <-- killed in order to turn off gpu
# unload modules
...
# turn off
-- pci "PCI bridge - Sunrise Point-LP PCI Express Root Port #1" -> 0000:00:1c.0
   -- device remove "3D controller - GP108M [GeForce MX150]" -> 0000:01:00.0
<process-hangs>

You can check process using the GPU with the following command and stop them manually:

$ nvx ps
10010 code

Hangs with no apparent cause:

If the nvx start command hangs during GPU turn off and there are no other processes using the GPU, that might be caused by a modeset=1 option set to the nvidia-drm kernel module. That option might be set in a file like /etc/modprobe.d/nvidia.conf, via GRUB or any other means to set kernel module parameters. By removing the nvidia-drm modeset=1 parameter, the nvx start should stop hanging.