Tensorrt Llm

TensorRT-LLM

NVIDIA's open-source library for optimizing LLM inference with state-of-the-art performance on NVIDIA GPUs.

When to use TensorRT-LLM

Use TensorRT-LLM when:

• Deploying on NVIDIA GPUs (A100, H100, GB200)
• Need maximum throughput (24,000+ tokens/sec on Llama 3)
• Require low latency for real-time applications
• Working with quantized models (FP8, INT4, FP4)
• Scaling across multiple GPUs or nodes

Use vLLM instead when:

• Need simpler setup and Python-first API
• Want PagedAttention without TensorRT compilation
• Working with AMD GPUs or non-NVIDIA hardware

Use llama.cpp instead when:

• Deploying on CPU or Apple Silicon
• Need edge deployment without NVIDIA GPUs
• Want simpler GGUF quantization format

Quick start

Installation

bashCopy code
# Docker (recommended)
docker pull nvidia/tensorrt_llm:latest

# pip install
pip install tensorrt_llm==1.2.0rc3

# Requires CUDA 13.0.0, TensorRT 10.13.2, Python 3.10-3.12

Basic inference

pythonCopy code
from tensorrt_llm import LLM, SamplingParams

# Initialize model
llm = LLM(model="meta-llama/Meta-Llama-3-8B")

# Configure sampling
sampling_params = SamplingParams(
    max_tokens=100,
    temperature=0.7,
    top_p=0.9
)

# Generate
prompts = ["Explain quantum computing"]
outputs = llm.generate(prompts, sampling_params)

for output in outputs:
    print(output.text)

Serving with trtllm-serve

bashCopy code
# Start server (automatic model download and compilation)
trtllm-serve meta-llama/Meta-Llama-3-8B \
    --tp_size 4 \              # Tensor parallelism (4 GPUs)
    --max_batch_size 256 \
    --max_num_tokens 4096

# Client request
curl -X POST http://localhost:8000/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "meta-llama/Meta-Llama-3-8B",
    "messages": [{"role": "user", "content": "Hello!"}],
    "temperature": 0.7,
    "max_tokens": 100
  }'

Key features

Performance optimizations

• In-flight batching: Dynamic batching during generation
• Paged KV cache: Efficient memory management
• Flash Attention: Optimized attention kernels
• Quantization: FP8, INT4, FP4 for 2-4× faster inference
• CUDA graphs: Reduced kernel launch overhead

Parallelism

• Tensor parallelism (TP): Split model across GPUs
• Pipeline parallelism (PP): Layer-wise distribution
• Expert parallelism: For Mixture-of-Experts models
• Multi-node: Scale beyond single machine

Advanced features

• Speculative decoding: Faster generation with draft models
• LoRA serving: Efficient multi-adapter deployment
• Disaggregated serving: Separate prefill and generation

Common patterns

Quantized model (FP8)

pythonCopy code
from tensorrt_llm import LLM

# Load FP8 quantized model (2× faster, 50% memory)
llm = LLM(
    model="meta-llama/Meta-Llama-3-70B",
    dtype="fp8",
    max_num_tokens=8192
)

# Inference same as before
outputs = llm.generate(["Summarize this article..."])

Multi-GPU deployment

pythonCopy code
# Tensor parallelism across 8 GPUs
llm = LLM(
    model="meta-llama/Meta-Llama-3-405B",
    tensor_parallel_size=8,
    dtype="fp8"
)

Batch inference

pythonCopy code
# Process 100 prompts efficiently
prompts = [f"Question {i}: ..." for i in range(100)]

outputs = llm.generate(
    prompts,
    sampling_params=SamplingParams(max_tokens=200)
)

# Automatic in-flight batching for maximum throughput

Performance benchmarks

Meta Llama 3-8B (H100 GPU):

• Throughput: 24,000 tokens/sec
• Latency: ~10ms per token
• vs PyTorch: 100× faster

Llama 3-70B (8× A100 80GB):

• FP8 quantization: 2× faster than FP16
• Memory: 50% reduction with FP8

Supported models

• LLaMA family: Llama 2, Llama 3, CodeLlama
• GPT family: GPT-2, GPT-J, GPT-NeoX
• Qwen: Qwen, Qwen2, QwQ
• DeepSeek: DeepSeek-V2, DeepSeek-V3
• Mixtral: Mixtral-8x7B, Mixtral-8x22B
• Vision: LLaVA, Phi-3-vision
• 100+ models on HuggingFace

References

• Optimization Guide - Quantization, batching, KV cache tuning
• Multi-GPU Setup - Tensor/pipeline parallelism, multi-node
• Serving Guide - Production deployment, monitoring, autoscaling

Resources

• Docs: https://nvidia.github.io/TensorRT-LLM/
• GitHub: https://github.com/NVIDIA/TensorRT-LLM
• Models: https://huggingface.co/models?library=tensorrt_llm