When using NVIDIA GPUs with SR-IOV (Single Root I/O Virtualization) disabled in the BIOS, it’s possible to encounter issues where the nvidia-smi command does not detect or list the GPU. This situation can arise due to several factors related to how the system’s firmware, drivers, and operating system interact with the hardware. Here’s how to diagnose and address the issue:

Understanding the Issue

1. SR-IOV and GPU Visibility:

• SR-IOV is a technology that allows a single PCIe device to appear as multiple separate physical devices to the host system. Disabling SR-IOV can affect how the GPU is exposed to the operating system and drivers.

2. Driver and Kernel Configuration:

• The nvidia-smi tool relies on the NVIDIA driver to interact with the GPU. If the GPU is not correctly initialized by the driver, nvidia-smi will not detect it.

3. IOMMU and Device Passthrough:

• Without SR-IOV, certain features or configurations might not work correctly, especially in systems expecting SR-IOV to manage multiple virtual functions (VFs) of a device.

Steps to Troubleshoot and Resolve

1. Verify GPU Presence at the Hardware Level

First, confirm that the system’s PCI bus detects the GPU. Use the lspci command to list all PCI devices:

lspci -nn | grep -i nvidia

This command should show the NVIDIA GPU with its vendor and device IDs. If the GPU does not appear here, it suggests a deeper issue, such as:

• The GPU is not properly seated in the PCIe slot.
• There is a hardware failure.
• The BIOS is not configuring the GPU properly.

2. Check IOMMU Settings in BIOS/UEFI

Ensure that the IOMMU (Intel VT-d or AMD-Vi) is enabled in the BIOS/UEFI, even if SR-IOV is disabled. The steps are:

• Reboot the machine and enter the BIOS/UEFI setup.
• Find the setting for IOMMU or VT-d/AMD-Vi and make sure it is enabled.
• Save and exit the BIOS/UEFI settings.

3. Load and Bind the Correct NVIDIA Driver

Make sure the correct NVIDIA driver is installed and the GPU is not bound to a different driver like vfio-pci or the open-source nouveau driver.

1. Check the Driver Binding:

• Use lsmod to list the loaded modules and see if the NVIDIA driver is loaded:
  bash lsmod | grep nvidia
• If the nvidia module is not listed, it might not be loaded or the GPU might be bound to a different driver.

2. Unbind from Incompatible Drivers:

• If the GPU is bound to another driver, such as vfio-pci or nouveau, you need to unbind it. For example:
  bash sudo rmmod nouveau
  or
  bash sudo rmmod vfio-pci

3. Rebind to the NVIDIA Driver:

• Rebind the GPU to the NVIDIA driver. You may need to manually specify the device IDs:
  bash sudo modprobe nvidia sudo echo "nvidia" > /sys/bus/pci/devices/0000:01:00.0/driver_override sudo echo 0000:01:00.0 > /sys/bus/pci/drivers_probe
• Replace 0000:01:00.0 with the actual PCI address of your GPU.

4. Reinstall or Update NVIDIA Drivers

If the driver binding steps do not resolve the issue, reinstall or update the NVIDIA drivers:

1. Uninstall Current Drivers:

   sudo apt-get purge nvidia*

2. Install or Reinstall NVIDIA Drivers:

• Download and install the latest NVIDIA drivers from the NVIDIA website.
• Alternatively, use a package manager like apt or yum to install the driver.

3. Reboot the System:

• Reboot the system after reinstalling the drivers to ensure they load correctly.

5. Check for Conflicts in Configuration Files

Sometimes, conflicts or misconfigurations in system files can cause the GPU to be misdetected or not initialized properly.

1. Review Configuration Files:

• Check /etc/modprobe.d and /etc/modules-load.d for any files that might blacklisting the nvidia driver or loading conflicting drivers.

2. Ensure Proper Driver Settings:

• Verify that no unnecessary modules are blacklisted or loaded. For example, ensure there is no blacklist for nvidia in /etc/modprobe.d/blacklist.conf.

6. Verify with nvidia-smi

Once the above steps are completed, run nvidia-smi to check if the GPU is now detected:

nvidia-smi

If the GPU appears, the issue is resolved. If not, proceed with additional steps or consider alternative debugging methods.

Additional Tips

• Check System Logs: System logs can provide more insight into why the GPU is not being detected. Check the logs using:

  sudo dmesg | grep -i nvidia
  sudo tail -f /var/log/syslog

• Consult Documentation: Refer to the documentation for your specific hardware and drivers for additional troubleshooting steps.
• Community and Support: Engage with the NVIDIA community forums or seek support from NVIDIA for persistent issues.

Conclusion

Why can’t the nvidia-smi command detect the GPU when NVIDIA GPUs, recognized as the best GPU dedicated servers, have SR-IOV disabled in the BIOS? By resolving this issue, you can understand and then follow the troubleshooting steps that help verify the configuration of Openstack services. After following all of these steps, administrators can boost the performance and reliability of GPU-enabled instances in Openstack environments.