Mockup Nvidia GPUs on Linux systems

A new open-source tool, Mock Nvidia GPUs, lets Linux developers simulate NVIDIA GPU telemetry for monitoring software by intercepting NVML and nvidia-smi calls, without emulating CUDA or actual GPU hardware. The tool, built with gcc and make, provides scenario files for idle, loaded, thermal, and multi-GPU states, and supports runtime scenario swapping by reloading JSON files on modification. It is designed to test monitoring applications safely without replacing host drivers.

Mock nvidia gpus in Linux for monitoring software that reads NVIDIA telemetry through NVML or nvidia-smi . It does not emulate CUDA, PCI hardware, kernel ioctls, MIG provisioning, or GPU computation. make make test Requirements: Linux, gcc , make , Python 3. export MOCK NVIDIA STATE="$PWD/scenarios/loaded.json" export LD LIBRARY PATH="$PWD/build${LD LIBRARY PATH:+:$LD LIBRARY PATH}" export PATH="$PWD/bin:$PATH" nvidia-smi nvidia-smi --query-gpu=uuid,name,utilization.gpu,memory.used,memory.total,temperature.gpu,power.draw,power.limit --format=csv,noheader,nounits python3 examples/read nvml.py Run the loader diagnostic before testing a third-party program: ./bin/diagnose-loader The build provides all common loader names: libnvidia-ml.so.1 , libnvidia-ml.so , libnvml.so.1 , and libnvml.so . NVTOP currently documents that it loads libnvml.so , rather than the canonical NVIDIA filename. For an application linked to NVML: LD LIBRARY PATH="$PWD/build" MOCK NVIDIA STATE="$PWD/scenarios/thermal.json" ./monitor If the application loads an absolute path, mount build/libnvidia-ml.so.1 over that library inside an isolated test container. Never replace the host driver library. LD LIBRARY PATH is commonly removed by sudo and ignored by confined Snap or setuid applications. A systemd service also needs both LD LIBRARY PATH and MOCK NVIDIA STATE in its unit environment. Run the tool directly as the same user while establishing basic compatibility. Point MOCK NVIDIA STATE at a scenario file to render a different operating face through nvidia-smi or the NVML library. Each mode is independent and can be swapped at runtime. scenarios/idle.json — a GPU at rest. Low GPU and memory utilization, an idle temperature, fans near their floor, and a minimal power draw. Clocks sit at their baseline speed. scenarios/loaded.json — a GPU running a busy compute workload. High GPU utilization, boosted graphics and memory clocks, and most of VRAM consumed. scenarios/thermal.json — a GPU at its thermal and power ceiling. Temperature approaches maximum, fans run at 100%, power draw is capped at the limit, the performance state sags, and ECC reports errors. scenarios/4gpus.json — four GPUs under a mixed workload: two H100s in a busy state and two L40S blades, one loaded and one idle. GPU order in the array determines the NVML index. The library reloads the JSON file when its modification time changes. Switch scenarios without restarting the monitored process: cp scenarios/thermal.json /tmp/mock-gpu.json export MOCK NVIDIA STATE=/tmp/mock-gpu.json edit or replace /tmp/mock-gpu.json while the collector runs Supported state fields are demonstrated in scenarios/loaded.json . Memory is specified in MiB and power in watts. NVML returns bytes and milliwatts as the real API does. For multiple GPUs, place one to eight device objects in gpus : { "gpus": { "name": "NVIDIA H100 80GB HBM3", "uuid": "GPU-FAKE-0001", "pci bus id": "00000000:01:00.0", "gpu utilization percent": 94, "vram total mib": 81559, "vram used mib": 74200, "temperature c": 78, "power draw w": 610, "power limit w": 700 }, { "name": "NVIDIA L40S", "uuid": "GPU-FAKE-0002", "pci bus id": "00000000:02:00.0", "gpu utilization percent": 20, "vram total mib": 46068, "vram used mib": 9000, "temperature c": 51, "power draw w": 160, "power limit w": 350 } } See scenarios/4gpus.json for a complete mixed-load example. GPU order in the array determines the NVML index. UUID and PCI bus ID must be unique. - initialization and shutdown - device count and handles by index or UUID - name, UUID, serial and PCI information - utilization, memory, temperature and fan speed - power draw and power limit - graphics, SM and memory clocks - performance state and compute mode - ECC mode and aggregate error count - running compute process count - driver and NVML versions Unsupported calls are absent. Add any required function to src/mock nvml.c using the same state loader and NVIDIA NVML function signature. This package validates collectors, dashboards, alerts and recommendation logic. It cannot validate the NVIDIA kernel driver, CUDA workloads, PCI discovery, DCGM diagnostics, ECC hardware, throttling behavior or real process accounting. Support the project and other projects like this by supporting the creator, feel free to reach out for other ways to contribute. - EVM: 0x6e8e3c2b31424266e7cff59e910df1587c317427 ERC-20, BEP-20, TRC-20, AVAX-C, SPL, MATIC, POL, ARB, BASE, TON - BTC: bc1qzzvcguvqjc6qhwe2y5vy38w2zke7hksukjhm68 - LTC: MPfm5QLKH1r9XxgWmH75Gyps4LDfX5c53L - SOL: GEaCMpnyM8tB5BU4RMuLm6tgMr3q9FgMHodxDxxAGby - DOGE: DPkJheSBTTkFv9oxnEwGsfvrcCvEWDVhVY