Inference

Running inference with GR00T models

This guide covers running inference with PyTorch or TensorRT acceleration for the GR00T policy.

Prerequisites

• Model checkpoint (e.g., nvidia/GR00T-N1.6-3B)
• Dataset in LeRobot format
• CUDA-enabled GPU

Installation

PyTorch mode

uv sync

uv sync --extra tensorrt

Quick start: PyTorch mode

python scripts/deployment/standalone_inference_script.py \
  --model-path nvidia/GR00T-N1.6-3B \
  --dataset-path /path/to/dataset \
  --embodiment-tag GR1 \
  --traj-ids 0 1 2 \
  --inference-mode pytorch \
  --action-horizon 8

TensorRT mode (2x faster)

TensorRT provides approximately 2x speedup for the action head (DiT) component.

Command-line arguments

standalone_inference_script.py

Argument	Default	Description
--model-path	(required)	Path to model checkpoint
--dataset-path	(required)	Path to LeRobot dataset
--embodiment-tag	GR1	Embodiment tag
--traj-ids	[0]	List of trajectory IDs to evaluate
--steps	200	Max steps per trajectory
--action-horizon	16	Action horizon for inference
--inference-mode	pytorch	pytorch or tensorrt
--trt-engine-path	./groot_n1d6_onnx/dit_model_bf16.trt	TensorRT engine path
--denoising-steps	4	Number of denoising steps
--skip-timing-steps	1	Steps to skip for timing (warmup)
--seed	42	Random seed for reproducibility
--video-backend	torchcodec	Video backend (decord, torchvision_av, torchcodec)

export_onnx_n1d6.py

Argument	Default	Description
--model-path	(required)	Path to model checkpoint
--dataset-path	(required)	Path to dataset (for input shape capture)
--embodiment-tag	GR1	Embodiment tag
--output-dir	./groot_n1d6_onnx	Output directory for ONNX model
--video-backend	torchcodec	Video backend

build_tensorrt_engine.py

Argument	Default	Description
--onnx	(required)	Path to ONNX model
--engine	(required)	Path to save TensorRT engine
--precision	bf16	Precision (fp32, fp16, bf16, fp8)
--workspace	8192	Workspace size in MB

Benchmarks

GR00T-N1.6-3B inference timing with 4 denoising steps:

The backbone (Vision Encoder + Language Model) timing is the same across all modes. Only the Action Head (DiT) is optimized with torch.compile or TensorRT.

Component-wise breakdown

| Device | Mode | Data Processing | Backbone | Action Head | E2E | Frequency | |--------|------|-----------------|----------|-------------|-----|-----------|| | RTX 5090 | PyTorch Eager | 2 ms | 18 ms | 38 ms | 58 ms | 17.3 Hz | | RTX 5090 | torch.compile | 2 ms | 18 ms | 16 ms | 37 ms | 27.3 Hz | | RTX 5090 | TensorRT | 2 ms | 18 ms | 11 ms | 31 ms | 32.1 Hz | | H100 | PyTorch Eager | 4 ms | 23 ms | 49 ms | 77 ms | 13.0 Hz | | H100 | torch.compile | 4 ms | 23 ms | 11 ms | 38 ms | 26.3 Hz | | H100 | TensorRT | 4 ms | 22 ms | 10 ms | 36 ms | 27.9 Hz | | RTX 4090 | PyTorch Eager | 2 ms | 25 ms | 55 ms | 82 ms | 12.2 Hz | | RTX 4090 | torch.compile | 2 ms | 25 ms | 17 ms | 44 ms | 22.8 Hz | | RTX 4090 | TensorRT | 2 ms | 24 ms | 16 ms | 43 ms | 23.3 Hz | | Orin | PyTorch Eager | 6 ms | 93 ms | 202 ms | 300 ms | 3.3 Hz | | Orin | torch.compile | 6 ms | 93 ms | 101 ms | 199 ms | 5.0 Hz | | Orin | TensorRT | 6 ms | 95 ms | 72 ms | 173 ms | 5.8 Hz |

Speedup vs PyTorch Eager

Device	Mode	E2E Speedup	Action Head Speedup
RTX 5090	torch.compile	1.58x	2.32x
RTX 5090	TensorRT	1.86x	3.59x
H100	torch.compile	2.02x	4.60x
H100	TensorRT	2.14x	4.80x
RTX 4090	torch.compile	1.87x	3.26x
RTX 4090	TensorRT	1.92x	3.48x
Orin	torch.compile	1.50x	2.00x
Orin	TensorRT	1.73x	2.80x

Run python scripts/deployment/benchmark_inference.py to generate benchmarks for your hardware.

Architecture

The TensorRT optimization targets the DiT (Diffusion Transformer) component of the action head, which is the main computational bottleneck during inference.

┌─────────────────────────────────────────────────────────────┐
│                    GR00T Policy                             │
│  ┌───────────────┐  ┌───────────────┐  ┌─────────────────┐  │
│  │ Vision Encoder│  │Language Model │  │  Action Head    │  │
│  │(Cosmos-Reason)│──│(Cosmos-Reason)│──│    (DiT)        │  │
│  └───────────────┘  └───────────────┘  └─────────────────┘  │
│                                              ▲              │
│                                              │              │
│                                    ┌─────────┴─────────┐    │
│                                    │ TensorRT Engine   │    │
│                                    │ (dit_model.trt)   │    │
│                                    └───────────────────┘    │
└─────────────────────────────────────────────────────────────┘

Troubleshooting

Engine build fails

• Ensure you have enough GPU memory (8GB+ recommended)
• Try reducing workspace size: --workspace 4096
• Ensure TensorRT version matches your CUDA version

ONNX export issues

• If export fails, ensure the model loads correctly in PyTorch first
• Check that the dataset path is valid and contains at least one trajectory