Arch Linux

obones

Member

Registered: 2019-04-11

Posts: 3

Prevent xorg from using a compute only GPU

Hello,

In order to do some ML related heavy computation, I have added a Nvidia Tesla P4 GPU card to my system that has an integrated Intel HD Graphics 530 (i915 driver)
That GPU card has no output connector and while I was able to tell Plasma not to use it, Xorg still shows in the usage list returned by nvidia-smi:

+---------------------------------------------------------------------------------------+
| NVIDIA-SMI 530.41.03              Driver Version: 530.41.03    CUDA Version: 12.1     |
|-----------------------------------------+----------------------+----------------------+
| GPU  Name                  Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf            Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|                                         |                      |               MIG M. |
|=========================================+======================+======================|
|   0  Tesla P4                        Off| 00000000:01:00.0 Off |                    0 |
| N/A   41C    P8                7W /  75W|      4MiB /  7680MiB |      0%      Default |
|                                         |                      |                  N/A |
+-----------------------------------------+----------------------+----------------------+

+---------------------------------------------------------------------------------------+
| Processes:                                                                            |
|  GPU   GI   CI        PID   Type   Process name                            GPU Memory |
|        ID   ID                                                             Usage      |
|=======================================================================================|
|    0   N/A  N/A      1674      G   /usr/lib/Xorg                                 4MiB |
+---------------------------------------------------------------------------------------+

As I'm chasing down some instabilities in this setup, I'm trying to figure a way to completely prevent Xorg from even considering that compute only GPU card.

I believe this is possible but I could only find outdated / unrelated documentation up to now.

Thanks in advance for any help.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,194

Re: Prevent xorg from using a compute only GPU

Create a snippet in /etc/X11/xorg.conf.d or so that reads

Section "Device"
   Identifier "intel"
   BusID "PCI:0:2:0" #Double check this with xorg log/lspci this needs to be the bus of your integrated card, 0:2:0 is generally the "most common" bus but it might differ
   Driver "modesetting"
EndSection

This should override the auto device lookup and only look for the one device you've explicitly specified.

Last edited by V1del (2023-06-13 12:59:31)

obones

Member

Registered: 2019-04-11

Posts: 3

Re: Prevent xorg from using a compute only GPU

Thanks a lot, it works and 0:2:0 was indeed the value for me

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 75,659

Re: Prevent xorg from using a compute only GPU

Please always remember to mark resolved threads by editing your initial posts subject - so others will know that there's no task left, but maybe a solution to find.
Thanks.

---

How to upload text · How to boot w/o GUI · Disable Windows Fast-Start! · Fix your xinitrc