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My computer has one integrated graphics card and 2 Nvidia RTX 3070 GPUS. I am using Ubuntu 20.04 and nvidia-driver-530.

lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation AlderLake-S GT1 (rev 0c)
01:00.0 VGA compatible controller: NVIDIA Corporation GA104 [GeForce RTX 3070 Lite Hash Rate] (rev a1)
05:00.0 VGA compatible controller: NVIDIA Corporation GA104 [GeForce RTX 3070 Lite Hash Rate] (rev a1)

I am currently trying to test my 3070 graphics cards with the Phoronix Test Suite.

I am using nvidia-prime and prime-select: on-demand to run the terminal on the intel iGPU and phoronix tests on the Nvidia 3070: prime-run phoronix-test-suite run unigine-heaven.

There were some issues getting nvidia-prime to work, so I followed the suggestions from this article: Prime-run command not found.

cat /usr/bin/prime-run
#!/bin/bash
export __NV_PRIME_RENDER_OFFLOAD=1
export __GLX_VENDOR_LIBRARY_NAME=nvidia
export __VK_LAYER_NV_optimus=NVIDIA_only
export VK_ICD_FILENAMES=/usr/share/vulkan/icd.d/nvidia_icd.json
exec "$@"

By using prime-run I am successfully able to run the phoronix test suite on GPU 0 which has bus id 01:00.0 / PCI:1:0:0.

However, I seem unable to run any tests with GPU 1 which has bus id 05:00.0 / PCI:5:0:0.

Modifying /etc/X11/xorg.conf by changing the bus number and rebooting as suggested by the following links didn't seem to do anything and still ran on GPU 0.

cat /etc/X11/xorg.conf
# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 530.41.03

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


Section "Files"
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      "Unknown"
    Option         "DPMS"
EndSection


Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"


BusID          "PCI:1:0:0"


BusID          "PCI:5:0:0"



EndSection


Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

In fact, I deleted etc/X11/xorg.conf and was able to run the phoronix tests on GPU 0 without the conf file at all. I would guess that one of the drivers or programs I run automatically selects the nvidia card with the lowest bus id.

I would like to know where I should look to change the settings or any configuration files in order to select the second RTX 3070 gpu with the bus id 05:00.0. I would be more than happy to provide any further information.

jameszp
  • 45

1 Answers1

1

In the prime-run script, I also need to set the variable

__NV_PRIME_RENDER_OFFLOAD_PROVIDER=NVIDIA-G{CARD#}

using the card identifier found in xrandr --listproviders.

The official Nvidia guide listed below has the resolution to this problem, but I did not read the guide closely enough and missed it on my first read.

https://download.nvidia.com/XFree86/Linux-x86_64/495.44/README/primerenderoffload.html

/etc/X11/xorg.conf is unnecessary for this solution.

I missed the part about the OFFLOAD_PROVIDER because I was accessing the headless server remotely from a client without any Xsession or graphics display.

The machine must be running some type of GUI and not just a headless terminal environment. In my case, I installed lightdm onto my server and then everything worked.

I believe that the graphics needs to be using x11/ xorg and not wayland. For gdm3, xorg can be set to run by uncommenting

#WaylandEnable=false

in /etc/gdm3/custom.conf and rebooting.

jameszp
  • 45