Repository Structure

This introductory guide presents the structure of the NeMo AutoModel repository, provides a brief overview of its parts, introduces concepts such as components and recipes, and explains how everything fits together.

What is NeMo AutoModel?

NeMo AutoModel is a PyTorch library for fine-tuning and pretraining large-scale models. In particular, it provides:

• Optimized implementations for training efficiency, including fused kernels and memory-saving techniques.
• Day-0 support for LLMs and VLMs available on the Hugging Face Hub.
• Seamless integration with Hugging Face datasets, tokenizers, and related tools.
• Distributed training strategies using FSDP2 and MegatronFSDP across multi-GPU and multi-node environments.
• End-to-end workflows with recipes for data preparation, training, and evaluation.

Repository Structure

The AutoModel source code is available under the nemo_automodel directory. It is organized into three directories:

• components/ - Self-contained modules
• recipes/ - End-to-end training workflows
• cli/ - CLI entry-point and job launcher dispatch.

Components Directory

The components/ directory contains isolated modules used in training loops. Each component is designed to be dependency-light and reusable without cross-module imports.

Directory Structure

The following directory listing shows all components along with explanations of their contents.

$ tree -L 1 nemo_automodel/components/
├── _peft/          - Implementations of PEFT methods, such as LoRA.
├── attention/      - Efficient attention modules and related utilities (e.g., flash attention, rotary embeddings).
├── checkpoint/     - Checkpoint save and load-related logic.
├── config/         - Utils to load YAML files and CLI-parsing helpers.
├── datasets/       - LLM and VLM datasets and utils (collate functions, preprocessing).
├── distributed/    - Distributed processing primitives (DDP, FSDP2, MegatronFSDP) and pipeline parallelism (AutoPipeline).
├── launcher/       - Job launcher for interactive and batch (Slurm, K8s) processing.
├── loggers/        - Metric/event logging for Weights & Biases and other tools.
├── loss/           - Loss functions (such as cross-entropy and linear cross-entropy, etc.).
├── models/         - Optimized model implementations for LLMs and VLMs.
├── moe/            - Mixture of Experts modules and routing utilities for scalable model architectures.
├── optim/          - Optimizers and LR schedulers, including fused or second-order variants.
├── quantization/   - Quantization layers and helpers for 4-bit/8-bit or other reduced-precision training and inference.
├── training/       - Training and fine-tuning utils.
└── utils/          - Small, dependency-free helpers (seed, profiler, timing, fs).

Key Features

• Each component can be used independently in other projects.
• Each component has its own dependencies, without cross-module imports.
• Unit tests are colocated with the component they cover.

Recipes Directory

Recipes define end-to-end workflows (data and model loading → training with custom loop → saving the output checkpoint) for a variety of tasks, such as training, fine-tuning, and knowledge distillation.

Available Recipes

The following directory listing shows all components along with explanations of their contents.

$ tree -L 2 nemo_automodel/recipes/
├── llm
│   ├── benchmark.py  - Benchmark recipe for LLMs
│   ├── kd.py         - Knowledge Distillation for LLMs
│   └── train_ft.py   - Train recipe for LLMs (Pretrain & Finetune SFT, PEFT).
└── vlm
    └── finetune.py   - Finetune recipe for VLMs (SFT, PEFT).

Run a Recipe

Recipes are launched via the automodel CLI:

$
automodel --nproc-per-node 2 examples/llm_finetune/llama3_2/llama3_2_1b_squad.yaml

The above command will fine-tune the Llama3.2-1B model on the SQuAD dataset with two GPUs using the llama3_2_1b_squad.yaml config. For a single-GPU run, omit --nproc-per-node:

$
automodel examples/llm_finetune/llama3_2/llama3_2_1b_squad.yaml

Each recipe imports the components it needs from the nemo_automodel/components/ catalog. The recipe/components structure enables you to:

• Decouple individual components and replace them with custom implementations when needed.
• Avoid rigid, class-based trainer structures by using linear scripts that expose training logic for maximum flexibility and control.

Configure a Recipe

An example YAML configuration is shown below. The complete config is available here:

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step_scheduler:
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  grad_acc_steps: 4
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  ckpt_every_steps: 1000
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  val_every_steps: 10  # will run every x number of gradient steps
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  num_epochs: 1
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model:
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  _target_: nemo_automodel.NeMoAutoModelForCausalLM.from_pretrained
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  pretrained_model_name_or_path: meta-llama/Llama-3.2-1B
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dataset:
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  _target_: nemo_automodel.components.datasets.llm.squad.make_squad_dataset
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  dataset_name: rajpurkar/squad
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  split: train

More recipe examples are available under the examples/ directory.

CLI Directory (cli/)

The automodel (or am) CLI application simplifies job execution across different environments, from single-GPU interactive sessions to batch multi-node runs. It supports interactive (local), SLURM, SkyPilot, and NeMo-Run launchers. The CLI lives at the repository root in the cli/ package, separate from the core nemo_automodel library.

Next Steps

Learn how to train models with NeMo AutoModel on:

• Your local workstation: See docs/launcher/local-workstation.md.
• A cluster: See docs/launcher/slurm.md.