Performance and Functionality Issues

1. For Windows Client Systems:

   1. Verify Installation:

      1. Use Windows Settings or PowerShell to confirm if the NVIDIA Control Panel app is installed.

      2. Ensure local or group policies do not block Microsoft Store apps.

2. Install the NVIDIA Control Panel APPX:

   1. Use the Windows Package Manager (winget) with the following command: winget install "NVIDIA Control Panel" --id 9NF8H0H7WMLT -s msstore --accept-package-agreements --accept-source-agreements

   2. Ensure required dependencies (e.g., Microsoft.UI.Xaml, Microsoft.VCLibs.x64) are installed.

3. For Windows Server Systems:

   1. Use the Standalone Installer: Download and install the NVIDIA Control Panel from the NV Licensing Portal.

      

      Figure 1 Standalone NVIDIA Control Panel Download from NV Licensing Portal

1. Verify NVIDIA Driver: Run nvidia-smi to ensure the GPU driver is installed.

2. Check NVIDIA Container Toolkit: Validate /etc/docker/daemon.json and supported components with nvidia-container-cli -k -d >(cat) info.

3. Restart Services: Restart Docker after ensuring the toolkit is configured properly.

1. Verify that the container is started with GPU support: docker run -it --entrypoint /bin/bash nvcr.io/nvidia/hpc-benchmarks:21.4-hpl

2. Check the container license: nvidia-smi -q | grep -i license. Ensure the command completes successfully.

3. For licensing configuration, refer to:

   1. NVIDIA Licensing User Guide

   2. GPU Operator Installation Guide

4. Check driver logs and ensure the nvidia-gridd service is running.

Citrix policies should be adjusted to negotiate the video encoder type to H.264 YUV420 by disabling the “Allow Visually Lossless Compression” policy to resolve this issue.

1. Open Device Manager and navigate to Display Adapters.

2. Double-click each adapter and check for Windows error codes under the General tab.

3. If an error code is present:

   1. Refer to Microsoft’s Device Manager Error Messages for troubleshooting guidance.

   2. Ensure the correct NVIDIA vGPU driver is installed and up to date.

   3. Restart the VM after installing or updating drivers to apply changes.

1. Understanding GPU channels and how they work:

   GPU channels are dedicated communication pathways that allow applications and system processes to interact with the GPU for accelerated computing. Each vGPU instance is allocated a specific number of GPU channels, which are consumed as applications request GPU resources.

   Channel allocation per vGPU is designed based on the maximum number of vGPU instances that can run concurrently on a physical GPU. Larger profiles support fewer instances and typically have more GPU channels, which can help improve multitasking and application stability.

2. Understanding how channel utilization relates to application behavior:

   Windows 11 introduces GPU acceleration to a wider range of applications compared to Windows 10. Core system applications such as MS Paint, Notepad, PowerShell, Snipping Tool, and Command Prompt now utilize GPU resources, increasing the overall demand for GPU channels. Different applications will have different channel utilization depending on their architecture and processing demands.

   As more applications adopt GPU acceleration in Windows 11, the baseline GPU channel usage increases. This can reduce the number of additional apps that can run concurrently before reaching channel exhaustion, potentially leading to performance bottlenecks or instability in virtualized environments.

3. Recognizing the symptoms of vGPU channel exhaustion:

   When all vGPU channels are consumed, applications may fail to launch or may crash, and system responsiveness degrades. The following errors are reported on the hypervisor host or in an NVIDIA bug report, when running vGPU 16.10, 17.6 and 18.1 and later releases:

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   Jun 26 08:01:25 srvxen06f vgpu-3[14276]: error: vmiop_log: (0x0): Guest attempted to allocate channel above its max channel limit 0xfb
           

   
   

4. Monitoring GPU channel usage:

   By monitoring GPU channel allocation, users can prevent channel exhaustion, optimize vGPU deployments, and ensure stable performance in virtualized environments.

   The channel_usage_threshold_percentage plugin parameter helps detect when workloads approach GPU channel exhaustion for specific hypervisors.

   Setting a threshold allows administrators to receive warnings when channel usage surpasses a defined percentage.

   By default, channel usage warnings are disabled, but administrators can enable them by setting a threshold percentage. For KVM hypervisors, the plugin parameter can be configured as follows:

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   echo "channel_usage_threshold_percentage=<percentage>" >
   /sys/bus/mdev/devices/<UUID>/nvidia/vgpu_params
           

   For example, to set the GPU channel usage warning threshold to 80%, run the following command:

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   echo "channel_usage_threshold_percentage=80" >
   /sys/bus/mdev/devices/<UUID>/nvidia/vgpu_params
           

   Note

   The above instructions are specific to KVM hypervisors. Path and configuration methods differ on other hypervisors. For more information, follow the the hypervisor-specific setup steps:

   • Citrix XenServer

   • VMware vSphere

   • Linux KVM Reference Hypervisors

   When running vGPU 16.10, 17.6 and 18.1 and later releases, once the usage surpasses the threshold, warning messages appear in the logs, indicating that channel utilization is approaching exhaustion. Example log output:

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   Sep 10 08:39:52 smc120-0003 nvidia-vgpu-mgr[313728]: notice: vmiop_log: Guest current channel usage 81% on engine 0x1 exceeds threshold channel usage 80%
           

   This feature is particularly useful during Proof-of-Concept (PoC) deployments to observe and optimize resource allocation before production deployment. Through proactive monitoring, administrators can detect potential channel exhaustion early, preventing system crashes and performance degradation by identifying workloads that consume excessive GPU channels. This insight allows for timely adjustments before issues escalate.

5. Optimizing vGPU profile selection:

   Selecting the right vGPU profile is crucial for preventing GPU channel exhaustion and ensuring stable performance. Organizations should prioritize profiles with larger frame buffers, as these provide more GPU channels per VM, reducing the likelihood of channel exhaustion. Additionally, conducting thorough sizing assessments is essential whenever there are any changes in the environment, including increasing workload demands or upgrading the Guest OS. For best practices, organizations should refer to the vGPU Sizing and Selection Guides to align deployment with recommended configurations.