# Transformers

With Transformers it's very easy to load any model in 4 or 8-bit, quantizing them on the fly with bitsandbytes primitives.

Please review the [bitsandbytes section in the Accelerate docs](https://huggingface.co/docs/transformers/v4.37.2/en/quantization#bitsandbytes).

Details about the BitsAndBytesConfig can be found [here](https://huggingface.co/docs/transformers/v4.37.2/en/main_classes/quantization#transformers.BitsAndBytesConfig).

> [!WARNING]
> **Beware: bf16 is the optimal compute data type!**
>
> If your hardware supports it, `bf16` is the optimal compute dtype. The default is `float32` for backward compatibility and numerical stability. `float16` often leads to numerical instabilities, but `bfloat16` provides the benefits of both worlds: numerical stability equivalent to float32, but combined with the memory footprint and significant computation speedup of a 16-bit data type. Therefore, be sure to check if your hardware supports `bf16` and configure it using the `bnb_4bit_compute_dtype` parameter in BitsAndBytesConfig:

```py
import torch
from transformers import BitsAndBytesConfig

quantization_config = BitsAndBytesConfig(load_in_4bit=True, bnb_4bit_compute_dtype=torch.bfloat16)
```

# PEFT
With `PEFT`, you can use QLoRA out of the box with `LoraConfig` and a 4-bit base model.

Please review the [bitsandbytes section in the Accelerate docs](https://huggingface.co/docs/peft/developer_guides/quantization#quantize-a-model).

# Accelerate

Bitsandbytes is also easily usable from within Accelerate.

Please review the [bitsandbytes section in the Accelerate docs](https://huggingface.co/docs/accelerate/en/usage_guides/quantization).

# Trainer for the optimizers

You can use any of the 8-bit and/or paged optimizers by simple passing them to the `transformers.Trainer` class on initialization.All bnb optimizers are supported by passing the correct string in `TrainingArguments`'s `optim` attribute - e.g. (`paged_adamw_32bit`).

See the [official API docs for reference](https://huggingface.co/docs/transformers/main_classes/trainer#transformers.Trainer).

Here we point out to relevant doc sections in transformers / peft / Trainer + very briefly explain how these are integrated:
e.g. for transformers state that you can load any model in 8-bit / 4-bit precision, for PEFT, you can use QLoRA out of the box with `LoraConfig` + 4-bit base model, for Trainer: all bnb optimizers are supported by passing the correct string in `TrainingArguments`'s `optim` attribute - e.g. (`paged_adamw_32bit`):

# Blog posts

- [Making LLMs even more accessible with bitsandbytes, 4-bit quantization and QLoRA](https://huggingface.co/blog/4bit-transformers-bitsandbytes)
- [A Gentle Introduction to 8-bit Matrix Multiplication for transformers at scale using Hugging Face Transformers, Accelerate and bitsandbytes](https://huggingface.co/blog/hf-bitsandbytes-integration)