quantize_llm.py

from argparse import ArgumentParser

from optimum.amd import BrevitasQuantizationConfig, BrevitasQuantizer
from optimum.amd.brevitas.accelerate_utils import calc_cpu_device_map, calc_gpu_device_map, offload_model, remove_hooks
from optimum.amd.brevitas.data_utils import compute_perplexity, get_dataset_for_model
from optimum.amd.brevitas.export import export_quantized_model
from transformers import AutoTokenizer


def main(args):
    return_val = {}
    tokenizer = AutoTokenizer.from_pretrained(args.model)

    use_accelerate = args.device == "auto"

    # Prepare the quantizer, specifying its configuration and loading the model.
    qconfig = BrevitasQuantizationConfig(
        apply_gptq=args.apply_gptq,
        apply_weight_equalization=args.apply_weight_equalization,
        activations_equalization=args.activations_equalization,
        is_static=args.is_static,
        weights_symmetric=True,
        activations_symmetric=args.is_static,  # ONNX export only supports unsigned for dynamic quantization
        gpu_device_map=args.gpu_device_map,
        cpu_device_map=args.cpu_device_map,
    )

    quantizer = BrevitasQuantizer.from_pretrained(args.model, device_map="cpu" if use_accelerate else args.device)

    # Load the data for calibration and evaluation.
    calibration_dataset = get_dataset_for_model(
        args.model,
        qconfig=qconfig,
        dataset_name="wikitext2",
        tokenizer=tokenizer,
        nsamples=args.nsamples,
        seqlen=args.seqlen,
        split="train",
        device=args.device if not use_accelerate else None,
        fuse_sequences=args.fuse_sequences,
    )

    validation_dataset = get_dataset_for_model(
        args.model,
        qconfig=qconfig,
        dataset_name="wikitext2",
        tokenizer=tokenizer,
        nsamples=args.nsamples,
        seqlen=args.seqlen,
        split="validation",
        device=args.device if not use_accelerate else None,
        fuse_sequences=args.fuse_sequences,
    )

    model = quantizer.model

    # Evaluation of the non-quantized model.
    if use_accelerate:
        model = offload_model(model, qconfig.gpu_device_map, qconfig.cpu_device_map)
    perplexity = compute_perplexity(model, validation_dataset, context_length=args.seqlen // 2, tokenizer=tokenizer)
    return_val["float_perplexity"] = perplexity
    print(f"Perplexity (original model): {perplexity}")

    quantized_model = quantizer.quantize(qconfig, calibration_dataset)

    # Evaluation of the quantized model.
    perplexity = compute_perplexity(
        quantized_model, validation_dataset, context_length=args.seqlen // 2, tokenizer=tokenizer
    )
    return_val["quant_perplexity"] = perplexity
    print(f"Perplexity (quantized model): {perplexity}")

    print("Exporting the model to ONNX...")
    if use_accelerate:
        remove_hooks(quantized_model)
    quantized_model = quantized_model.to("cpu")

    # Export to ONNX through optimum.exporters.
    export_quantized_model(quantized_model, args.onnx_output_path)
    return return_val


if __name__ == "__main__":
    parser = ArgumentParser(description="Quantize LLMs from 🤗 Transformers with AMD Brevitas")
    parser.add_argument(
        "--model",
        type=str,
        default="facebook/opt-125m",
        help="Model checkpoint to quantize. Can either be a local path to a model folder, or a model on Hugging Face Hub. Example: facebook/opt-125m",
    )
    parser.add_argument(
        "--apply-gptq",
        action="store_true",
        default=False,
        help="Apply the GPTQ algorithm during quantization (Note, currently slow!). This option requires a calibration dataset.",
    )
    parser.add_argument(
        "--apply-weight-equalization",
        action="store_true",
        default=False,
        help="Apply the weight equalization algorithm.",
    )
    parser.add_argument(
        "--apply-bias-correction", action="store_true", default=False, help="Apply the bias correction algorithm."
    )
    parser.add_argument(
        "--activations-equalization",
        type=str,
        choices=[None, "cross_layer", "layerwise"],
        default=None,
        help="Apply the activation equalization (SmoothQuant) algorithm (choices: [%(choices)s], default: %(default)s). This option requires a calibration dataset.",
    )
    parser.add_argument(
        "--is-static",
        action="store_true",
        default=False,
        help="Whether to do static quantization of the activations (default: %(default)s), with pre-computed quantizaton parameters ahead of inference. This option requires a calibration dataset.",
    )
    parser.add_argument(
        "--seqlen",
        type=int,
        default=128,
        help="Sequence length to use during calibration (default: %(default)s).",
    )
    parser.add_argument(
        "--nsamples",
        type=int,
        default=128,
        help="Number of samples to use during calibration & validation (default: %(default)s).",
    )
    parser.add_argument(
        "--fuse-sequences",
        action="store_true",
        default=False,
        help="Whether to merge the dataset sequences in case they are shorter than the requested number of samples per sequence. This is useful in case you would like to quantize or evaluate on long sequences (default: %(default)s).",
    )
    parser.add_argument(
        "--device",
        type=str,
        choices=["cpu", "cuda:0", "auto"],
        default="auto",
        help='Device to run the example on (e.q., "cpu", "cuda:0", "auto"). "auto" will automatically select the device using HuggingFace Accelerate (choices: [%(choices)s], default: %(default)s).',
    )
    parser.add_argument(
        "--onnx-output-path",
        type=str,
        default="llm_quantized_onnx",
        help="Location to store the output ONNX model (default: %(default)s)",
    )

    args = parser.parse_args()

    # Specify how much of each device should set aside for accelerate's offload functions
    # The absolute margin is in bytes & the relative margin is a ratio
    # The margins are the portions of the device which should be reserved for other functions
    # (not accelerate)
    args.gpu_device_map = calc_gpu_device_map(absolute_mem_margin=2.0 * 1e9, relative_mem_margin=0.3)
    args.cpu_device_map = calc_cpu_device_map(absolute_mem_margin=2.0 * 1e9, relative_mem_margin=0.3)

    main(args)