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FBGEMM FP8

With FBGEMM FP8 quantization method, you can quantize your model in FP8 (W8A8):

- the weights will be quantized in 8bit (FP8) per channel
- the activation will be quantized in 8bit (FP8) per token

It relies on the FBGEMM library which provides efficient low-precision general matrix multiplication for small batch sizes and support for accuracy-loss minimizing techniques such as row-wise quantization and outlier-aware quantization.

You need a GPU with compute capability>=9 (e.g. H100)

Before you begin, make sure the following libraries are installed with their latest version:

    pip install --upgrade accelerate fbgemm-gpu torch

If you are having issues with fbgemm-gpu and torch library, you might need to install the nightly release. You can follow the instruction here

    from transformers import FbgemmFp8Config, AutoModelForCausalLM, AutoTokenizer

    model_name = "meta-llama/Meta-Llama-3-8B"
    quantization_config = FbgemmFp8Config()
    quantized_model = AutoModelForCausalLM.from_pretrained(model_name, device_map="auto", quantization_config=quantization_config)

    tokenizer = AutoTokenizer.from_pretrained(model_name)
    input_text = "What are we having for dinner?"
    input_ids = tokenizer(input_text, return_tensors="pt").to("cuda")

    output = quantized_model.generate(**input_ids, max_new_tokens=10)
    print(tokenizer.decode(output[0], skip_special_tokens=True))

A quantized model can be saved via “saved_pretrained” and be reused again via the “from_pretrained”.

    quant_path = "/path/to/save/quantized/model"
    model.save_pretrained(quant_path)
    model = AutoModelForCausalLM.from_pretrained(quant_path, device_map="auto")

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