distributed-llm-pretraining-torchtitan

Files (5)

• SKILL.md
• checkpoint.md · references/
• custom-models.md · references/
• float8.md · references/
• fsdp.md · references/

SKILL.md (first lines)

# TorchTitan - PyTorch Native Distributed LLM Pretraining

## Quick start

TorchTitan is PyTorch's official platform for large-scale LLM pretraining with composable 4D parallelism (FSDP2, TP, PP, CP), achieving 65%+ speedups over baselines on H100 GPUs.

**Installation**:
```bash
# From PyPI (stable)
pip install torchtitan

# From source (latest features, requires PyTorch nightly)
git clone https://github.com/pytorch/torchtitan
cd torchtitan
pip install -r requirements.txt
```

**Download tokenizer**:
```bash
# Get HF token from https://huggingface.co/settings/tokens
python scripts/download_hf_assets.py --repo_id meta-llama/Llama-3.1-8B --assets tokenizer --hf_token=...
```

**Start training on 8 GPUs**:
```bash
CONFIG_FILE="./torchtitan/models/llama3/train_configs/llama3_8b.toml" ./run_train.sh
```

## Common workflows

### Workflow 1: Pretrain Llama 3.1 8B on single node

Copy this checklist:

```
Single Node Pretraining:
- [ ] Step 1: Download tokenizer
- [ ] Step 2: Configure training
- [ ] Step 3: Launch training
- [ ] Step 4: Monitor and checkpoint
```

**Step 1: Download tokenizer**

```bash
python scripts/download_hf_assets.py \
  --repo_id meta-llama/Llama-3.1-8B \
  --assets tokenizer \
  --hf_token=YOUR_HF_TOKEN
```

**Step 2: Configure training**

Edit or create a TOML config file:

```toml
# llama3_8b_custom.toml
[job]
dump_folder = "./outputs"
description = "Llama 3.1 8B training"

[model]
name = "llama3"
flavor = "8B"
hf_assets_path = "./assets/hf/Llama-3.1-8B"

[optimizer]
name = "AdamW"
lr = 3e-4

[lr_scheduler]
warmup_steps = 200

[training]
local_batch_size = 2
seq_len = 8192
max_norm = 1.0
steps = 1000
dataset = "c4"

[parallelism]
data_parallel_shard_degree = -1  # Use all GPUs for FSDP

[activation_checkpoint]
mode = "selective"
selective_ac_option = "op"

[checkpoint]
enable = true
folder = "checkpoint"
interval = 500
```

**Step 3: Launch training**

```bash
# 8 GPUs on single node
CONFIG_FILE="./llama3_8b_custom.toml" ./run_train.sh

# Or explicitly with torchrun
torchrun --nproc_per_node=8 \
  -m torchtitan.train \
  --job.config_file ./llama3_8b_custom.toml
```

**Step 4: Monitor and checkpoint**

TensorBoard logs are saved to `./outputs/tb/`:
```bash
tensorboard --logdir ./outputs/tb
```

### Workflow 2: Multi-node training with SLURM

```
Multi-Node Training:
- [ ] Step 1: Configure parallelism for scale
- [ ] Step 2: Set up SLURM script
- [ ] Step 3: Submit job

From Tommy-yw/RunbookHermes, MIT.

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