Stop Fedora from scheduling GPU process on secondary GPU

Ask Fedora
1

Hi folks,

I am facing an annoying issue at the moment. I have several GPUs in my system. One Intel GPU that is supposed to be used for GPU processes and several Nvidia GPUs that are supposed to be used for compute.

The issue is that, by default, Fedora schedules processes on the Nvidia GPUs too, and these processes keep me from using the features I need since the nvidia tools complain that there are clients using the GPUs.

After start the following process spawn on the Nvidia GPUs for example but it is a general problem.

1. /usr/bin/gnome-shell 
2. /usr/bin/Xwayland
3. /usr/bin/gjs-console
4.  /usr/bin/gjs
5. /usr/bin/ptyxis

How can I instruct Fedora to only schedule GPU tasks on the GPU I specify, the primary GPU, and not a secondary or tertiary GPU.

Thank you for any input on the matter.

2

huh..
ah.. i only have one laptop with an integrated intel and a mobile Nvidia that I can compare with..

to get the nvidia to be used automatically I had to write a dbus rule specific for mutter (which is gnome’s desktop session thing) and tell it to use the NV card. If i didnt make that manual config change, I’d have to start applicatins specifically on the NV via either some sort of env variable change, or using the context menu in the UI to select the discrete gpu.

Its sort of the exact oppposite of your situation.

3

So I spend some time looking into this and it appears that there are two drivers, the regular driver with display output, as well as the compute only driver.

There is no direct way to stop desktop environments to schedule processes on the GPU if you use the regular driver. You need to install the compute only driver if you want the driver to be free from being used by GUI processes.

As of today the rpmfusion repository does not offer a compute only driver, it offers only the regular driver. So in case of Fedora you need to have the rpmfusion repository disabled, or at least you need to block dnf from looking for NVIDIA specific packages on there, and you need to install the official compute only driver from the NVIDIA repositories.

Instructions how to do this on Fedora 42 are to be found in the following link. Be aware that currently there are two drivers, the open-source driver and the proprietary driver. For modern NVIDIA cards the open-source driver is recommended, for newest generation like Blackwell even required.

To see which cards are supported by the open-source NVIDIA driver refer to the following link.

Hope this helps anyone running into the same problem with Fedora.

4

I’m thinking this could be wrangled with xorg.conf snippets.

Some of those apps might also respond to GSK_RENDERER; it defaults to Vulkan and might prefer high-performance GPUs. GSK_RENDERER=cairo might disable all GPU usage.

5

I thought that the xorg.conf is irrelevant for Wayland.