# Quantize to NVFP4

> Quantize a model to NVFP4 to run on Spark

## Table of Contents

- [Overview](#overview)
  - [NVFP4 on Blackwell](#nvfp4-on-blackwell)
- [Instructions](#instructions)

---

## Overview

## Basic Idea

### NVFP4 on Blackwell

- **What it is:** A new 4-bit floating-point format for NVIDIA Blackwell GPUs.
- **How it works:** Uses two levels of scaling (local per-block + global tensor) to keep accuracy while using fewer bits.
- **Why it matters:**
  - Cuts memory use ~3.5x vs FP16 and ~1.8x vs FP8
  - Keeps accuracy close to FP8 (usually <1% loss)
  - Improves speed and energy efficiency for inference


## What you'll accomplish

You'll quantize the DeepSeek-R1-Distill-Llama-8B model using NVIDIA's TensorRT Model Optimizer
inside a TensorRT-LLM container, producing an NVFP4 quantized model for deployment on NVIDIA DGX Spark.


## What to know before starting

- Working with Docker containers and GPU-accelerated workloads
- Understanding of model quantization concepts and their impact on inference performance
- Experience with NVIDIA TensorRT and CUDA toolkit environments
- Familiarity with Hugging Face model repositories and authentication

## Prerequisites

- NVIDIA Spark device with Blackwell architecture GPU
- Docker installed with GPU support
- NVIDIA Container Toolkit configured
- Available storage for model files and outputs
- Hugging Face account with access to the target model

Verify your setup:
```bash
## Check Docker GPU access
docker run --rm --gpus all nvcr.io/nvidia/tensorrt-llm/release:spark-single-gpu-dev nvidia-smi

## Verify sufficient disk space
df -h .
```

## Time & risk

**Estimated duration**: 45-90 minutes depending on network speed and model size

**Risks**:
- Model download may fail due to network issues or Hugging Face authentication problems
- Quantization process is memory-intensive and may fail on systems with insufficient GPU memory
- Output files are large (several GB) and require adequate storage space

**Rollback**: Remove the output directory and any pulled Docker images to restore original state.

## Instructions

## Step 1. Configure Docker permissions

To easily manage containers without sudo, you must be in the `docker` group. If you choose to skip this step, you will need to run Docker commands with sudo.

Open a new terminal and test Docker access. In the terminal, run:

```bash
docker ps
```

If you see a permission denied error (something like `permission denied while trying to connect to the Docker daemon socket`), add your user to the docker group:

```bash
sudo usermod -aG docker $USER
```

> **Warning**: After running usermod, you must log out and log back in to start a new
> session with updated group permissions.

## Step 2. Prepare the environment

Create a local output directory where the quantized model files will be stored. This directory will be mounted into the container to persist results after the container exits.

```bash
mkdir -p ./output_models
chmod 755 ./output_models
```

## Step 3. Authenticate with Hugging Face

Ensure you have access to the DeepSeek model by setting your Hugging Face authentication token.

```bash
## Export your Hugging Face token as an environment variable
## Get your token from: https://huggingface.co/settings/tokens
export HF_TOKEN="your_token_here"
```

The token will be automatically used by the container for model downloads.

## Step 4. Run the TensorRT Model Optimizer container

Launch the TensorRT-LLM container with GPU access, IPC settings optimized for multi-GPU workloads, and volume mounts for model caching and output persistence.

```bash
docker run --rm -it --gpus all --ipc=host --ulimit memlock=-1 --ulimit stack=67108864 \
  -v "./output_models:/workspace/output_models" \
  -v "$HOME/.cache/huggingface:/root/.cache/huggingface" \
  -e HF_TOKEN=$HF_TOKEN \
  nvcr.io/nvidia/tensorrt-llm/release:spark-single-gpu-dev \
  bash -c "
    git clone -b 0.35.0 --single-branch https://github.com/NVIDIA/TensorRT-Model-Optimizer.git /app/TensorRT-Model-Optimizer && \
    cd /app/TensorRT-Model-Optimizer && pip install -e '.[dev]' && \
    export ROOT_SAVE_PATH='/workspace/output_models' && \
    /app/TensorRT-Model-Optimizer/examples/llm_ptq/scripts/huggingface_example.sh \
    --model 'deepseek-ai/DeepSeek-R1-Distill-Llama-8B' \
    --quant nvfp4 \
    --tp 1 \
    --export_fmt hf
  "
```

Note: You may encounter this `pynvml.NVMLError_NotSupported: Not Supported`. This is expected in some environments, does not affect results, and will be fixed in an upcoming release.
Note: If your model is too large, you may encounter an out of memory error. You can try quantizing a smaller model instead.

This command:
- Runs the container with full GPU access and optimized shared memory settings
- Mounts your output directory to persist quantized model files
- Mounts your Hugging Face cache to avoid re-downloading the model
- Clones and installs the TensorRT Model Optimizer from source
- Executes the quantization script with NVFP4 quantization parameters

## Step 5. Monitor the quantization process

The quantization process will display progress information including:
- Model download progress from Hugging Face
- Quantization calibration steps
- Model export and validation phases

## Step 6. Validate the quantized model

After the container completes, verify that the quantized model files were created successfully.

```bash
## Check output directory contents
ls -la ./output_models/

## Verify model files are present
find ./output_models/ -name "*.bin" -o -name "*.safetensors" -o -name "config.json"
```

You should see model weight files, configuration files, and tokenizer files in the output directory.

## Step 7. Test model loading

Verify the quantized model can be loaded properly using a simple Python test.

```bash

export MODEL_PATH="./output_models/saved_models_DeepSeek-R1-Distill-Llama-8B_nvfp4_hf/"

docker run \
  -e HF_TOKEN=$HF_TOKEN \
  -v $HOME/.cache/huggingface/:/root/.cache/huggingface/ \
  -v "$MODEL_PATH:/workspace/model" \
  --rm -it --ulimit memlock=-1 --ulimit stack=67108864 \
  --gpus=all --ipc=host --network host \
  nvcr.io/nvidia/tensorrt-llm/release:spark-single-gpu-dev \
  bash -c '
    python examples/llm-api/quickstart_advanced.py \
      --model_dir /workspace/model/ \
      --prompt "Paris is great because" \
      --max_tokens 64
    '
```

## Step 8. Troubleshooting

| Symptom | Cause | Fix |
|---------|--------|-----|
| "Permission denied" when accessing Hugging Face | Missing or invalid HF token | Run `huggingface-cli login` with valid token |
| Container exits with CUDA out of memory | Insufficient GPU memory | Reduce batch size or use a machine with more GPU memory |
| Model files not found in output directory | Volume mount failed or wrong path | Verify `$(pwd)/output_models` resolves correctly |
| Git clone fails inside container | Network connectivity issues | Check internet connection and retry |
| Quantization process hangs | Container resource limits | Increase Docker memory limits or use --ulimit flags |

## Step 8. Cleanup and rollback

To clean up the environment and remove generated files:

> **Warning:** This will permanently delete all quantized model files and cached data.

```bash
## Remove output directory and all quantized models
rm -rf ./output_models

## Remove Hugging Face cache (optional)
rm -rf ~/.cache/huggingface

## Remove Docker image (optional)
docker rmi nvcr.io/nvidia/tensorrt-llm/release:spark-single-gpu-dev
```

## Step 9. Next steps

The quantized model is now ready for deployment. Common next steps include:
- Benchmarking inference performance compared to the original model
- Integrating the quantized model into your inference pipeline
- Deploying to NVIDIA Triton Inference Server for production serving
- Running additional validation tests on your specific use cases
