test_bitsandbytes.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
'''Tests whether bitsandbytes computation is enabled correctly.

Run `pytest tests/quantization/test_bitsandbytes.py`.
'''

import gc

import pytest
import torch
from transformers import BitsAndBytesConfig

from tests.quantization.utils import is_quant_method_supported

from ..models.utils import check_embeddings_close
from ..utils import compare_two_settings, create_new_process_for_each_test

models_4bit_to_test = [
    ("facebook/opt-125m", "quantize opt model inflight"),
    ("mistralai/Mistral-7B-Instruct-v0.3",
     "quantize inflight model with both HF and Mistral format weights")
]

models_4bit_to_embedding_test = [
    ("intfloat/e5-mistral-7b-instruct", "quantize embedding model inflight"),
]

models_pre_qaunt_4bit_to_test = [
    ('PrunaAI/Einstein-v6.1-Llama3-8B-bnb-4bit-smashed',
     'read pre-quantized 4-bit FP4 model'),
    ('poedator/opt-125m-bnb-4bit', 'read pre-quantized 4-bit NF4 opt model'),
]

models_pre_quant_8bit_to_test = [
    ('meta-llama/Llama-Guard-3-8B-INT8',
     'read pre-quantized llama 8-bit model'),
    ("yec019/fbopt-350m-8bit", "read pre-quantized 8-bit opt model"),
]


@pytest.mark.skipif(not is_quant_method_supported("bitsandbytes"),
                    reason='bitsandbytes is not supported on this GPU type.')
@pytest.mark.parametrize("model_name, description", models_4bit_to_test)
@create_new_process_for_each_test()
def test_load_4bit_bnb_model(hf_runner, vllm_runner, example_prompts,
                             model_name, description) -> None:

    hf_model_kwargs = dict(quantization_config=BitsAndBytesConfig(
        load_in_4bit=True))
    validate_generated_texts(hf_runner, vllm_runner, example_prompts[:1],
                             model_name, False, hf_model_kwargs)


@pytest.mark.skipif(not is_quant_method_supported("bitsandbytes"),
                    reason='bitsandbytes is not supported on this GPU type.')
@pytest.mark.parametrize("model_name, description",
                         models_pre_qaunt_4bit_to_test)
@create_new_process_for_each_test()
def test_load_pre_quant_4bit_bnb_model(hf_runner, vllm_runner, example_prompts,
                                       model_name, description) -> None:

    validate_generated_texts(hf_runner, vllm_runner, example_prompts[:1],
                             model_name, True)


@pytest.mark.skipif(not is_quant_method_supported("bitsandbytes"),
                    reason='bitsandbytes is not supported on this GPU type.')
@pytest.mark.parametrize("model_name, description",
                         models_pre_quant_8bit_to_test)
@create_new_process_for_each_test()
def test_load_8bit_bnb_model(hf_runner, vllm_runner, example_prompts,
                             model_name, description) -> None:

    validate_generated_texts(hf_runner, vllm_runner, example_prompts[:1],
                             model_name, True)


@pytest.mark.skipif(torch.cuda.device_count() < 2,
                    reason='Test requires at least 2 GPUs.')
@pytest.mark.skipif(not is_quant_method_supported("bitsandbytes"),
                    reason='bitsandbytes is not supported on this GPU type.')
@pytest.mark.parametrize("model_name, description", models_4bit_to_test)
@create_new_process_for_each_test()
def test_load_tp_4bit_bnb_model(hf_runner, vllm_runner, example_prompts,
                                model_name, description) -> None:

    hf_model_kwargs = dict(quantization_config=BitsAndBytesConfig(
        load_in_4bit=True))
    validate_generated_texts(hf_runner,
                             vllm_runner,
                             example_prompts[:1],
                             model_name,
                             False,
                             hf_model_kwargs,
                             vllm_tp_size=2)


@pytest.mark.skipif(torch.cuda.device_count() < 2,
                    reason='Test requires at least 2 GPUs.')
@pytest.mark.skipif(not is_quant_method_supported("bitsandbytes"),
                    reason='bitsandbytes is not supported on this GPU type.')
@pytest.mark.parametrize("model_name, description", models_4bit_to_test)
@create_new_process_for_each_test()
def test_load_pp_4bit_bnb_model(model_name, description) -> None:
    common_args = [
        "--disable-log-stats",
        "--disable-log-requests",
        "--dtype",
        "bfloat16",
        "--enable-prefix-caching",
        "--quantization",
        "bitsandbytes",
        "--gpu-memory-utilization",
        "0.7",
    ]
    pp_args = [
        *common_args,
        "--pipeline-parallel-size",
        "2",
    ]
    compare_two_settings(model_name, common_args, pp_args)


@pytest.mark.skipif(not is_quant_method_supported("bitsandbytes"),
                    reason='bitsandbytes is not supported on this GPU type.')
@pytest.mark.parametrize("model_name, description",
                         models_4bit_to_embedding_test)
@pytest.mark.parametrize("dtype", ["half"])
@create_new_process_for_each_test()
def test_4bit_bnb_embedding_model(
    model_name,
    description,
    hf_runner,
    vllm_runner,
    example_prompts,
    dtype: str,
) -> None:

    # The example_prompts has ending "\n", for example:
    # "Write a short story about a robot that dreams for the first time.\n"
    # sentence_transformers will strip the input texts, see:
    # https://github.com/UKPLab/sentence-transformers/blob/v3.1.1/sentence_transformers/models/Transformer.py#L159
    # This makes the input_ids different between hf_model and vllm_model.
    # So we need to strip the input texts to avoid test failing.
    example_prompts = [str(s).strip() for s in example_prompts]

    # Inflight 4bit quantization
    hf_model_kwargs = dict(quantization_config=BitsAndBytesConfig(
        load_in_4bit=True))
    with hf_runner(
            model_name,
            dtype=dtype,
            model_kwargs=hf_model_kwargs,
            is_sentence_transformer=True,
    ) as hf_model:
        hf_outputs = hf_model.encode(example_prompts)

    with vllm_runner(model_name,
                     task="embed",
                     dtype=dtype,
                     gpu_memory_utilization=0.5,
                     quantization="bitsandbytes") as vllm_model:
        vllm_outputs = vllm_model.embed(example_prompts)
    check_embeddings_close(
        embeddings_0_lst=hf_outputs,
        embeddings_1_lst=vllm_outputs,
        name_0="hf",
        name_1="vllm",
        tol=5e-2,
    )


def log_generated_texts(prompts, outputs, runner_name):
    logged_texts = []
    for i, (_, generated_text) in enumerate(outputs):
        log_entry = {
            "prompt": prompts[i],
            "runner_name": runner_name,
            "generated_text": generated_text,
        }
        logged_texts.append(log_entry)
    return logged_texts


def validate_generated_texts(hf_runner,
                             vllm_runner,
                             prompts,
                             model_name,
                             pre_quant=False,
                             hf_model_kwargs=None,
                             vllm_tp_size=1):

    # NOTE: run vLLM first, as it requires a clean process
    # when using distributed inference
    with vllm_runner(model_name,
                     quantization=None if pre_quant else 'bitsandbytes',
                     tensor_parallel_size=vllm_tp_size,
                     enforce_eager=False) as llm:
        vllm_outputs = llm.generate_greedy(prompts, 8)
        vllm_logs = log_generated_texts(prompts, vllm_outputs, "VllmRunner")

    # Clean up the GPU memory for the next test
    gc.collect()
    torch.cuda.empty_cache()

    if hf_model_kwargs is None:
        hf_model_kwargs = {}

    # Run with HF runner
    with hf_runner(model_name, model_kwargs=hf_model_kwargs) as llm:
        hf_outputs = llm.generate_greedy(prompts, 8)
        hf_logs = log_generated_texts(prompts, hf_outputs, "HfRunner")

    # Clean up the GPU memory for the next test
    gc.collect()
    torch.cuda.empty_cache()

    # Compare the generated strings
    for hf_log, vllm_log in zip(hf_logs, vllm_logs):
        hf_str = hf_log["generated_text"]
        vllm_str = vllm_log["generated_text"]
        prompt = hf_log["prompt"]

        assert hf_str == vllm_str, (f"Model: {model_name}"
                                    f"Mismatch between HF and vLLM outputs:\n"
                                    f"Prompt: {prompt}\n"
                                    f"HF Output: '{hf_str}'\n"
                                    f"vLLM Output: '{vllm_str}'")