vllm.benchmarks.throughput ¶

def add_cli_args(parser: argparse.ArgumentParser):
    parser.add_argument(
        "--backend",
        type=str,
        choices=["vllm", "hf", "mii", "vllm-chat"],
        default="vllm",
    )
    parser.add_argument(
        "--dataset-name",
        type=str,
        choices=[
            "sharegpt",
            "random",
            "sonnet",
            "burstgpt",
            "hf",
            "prefix_repetition",
            "random-mm",
            "random-rerank",
        ],
        help="Name of the dataset to benchmark on.",
        default="sharegpt",
    )
    parser.add_argument(
        "--dataset",
        type=str,
        default=None,
        help="Path to the ShareGPT dataset, will be deprecated in\
            the next release. The dataset is expected to "
        "be a json in form of list[dict[..., conversations: "
        "list[dict[..., value: <prompt_or_response>]]]]",
    )
    parser.add_argument(
        "--dataset-path", type=str, default=None, help="Path to the dataset"
    )
    parser.add_argument(
        "--input-len",
        type=int,
        default=None,
        help="Input prompt length for each request",
    )
    parser.add_argument(
        "--output-len",
        type=int,
        default=None,
        help="Output length for each request. Overrides the "
        "output length from the dataset.",
    )
    parser.add_argument(
        "--n", type=int, default=1, help="Number of generated sequences per prompt."
    )
    parser.add_argument(
        "--num-prompts", type=int, default=1000, help="Number of prompts to process."
    )
    parser.add_argument(
        "--hf-max-batch-size",
        type=int,
        default=None,
        help="Maximum batch size for HF backend.",
    )
    parser.add_argument(
        "--output-json",
        type=str,
        default=None,
        help="Path to save the throughput results in JSON format.",
    )
    parser.add_argument(
        "--async-engine",
        action="store_true",
        default=False,
        help="Use vLLM async engine rather than LLM class.",
    )
    parser.add_argument(
        "--disable-frontend-multiprocessing",
        action="store_true",
        default=False,
        help="Disable decoupled async engine frontend.",
    )
    parser.add_argument(
        "--disable-detokenize",
        action="store_true",
        help=(
            "Do not detokenize the response (i.e. do not include "
            "detokenization time in the measurement)"
        ),
    )
    # LoRA
    parser.add_argument(
        "--lora-path",
        type=str,
        default=None,
        help="Path to the lora adapters to use. This can be an absolute path, "
        "a relative path, or a Hugging Face model identifier.",
    )
    parser.add_argument(
        "--prefix-len",
        type=int,
        default=0,
        help="Number of fixed prefix tokens before the random "
        "context in a request (default: 0).",
    )

    # hf dtaset
    parser.add_argument(
        "--hf-subset",
        type=str,
        default=None,
        help="Subset of the HF dataset.",
    )
    parser.add_argument(
        "--hf-split",
        type=str,
        default=None,
        help="Split of the HF dataset.",
    )
    parser.add_argument(
        "--profile",
        action="store_true",
        default=False,
        help="Use vLLM Profiling. --profiler-config must be provided on the server.",
    )

    # prefix repetition dataset
    parser.add_argument(
        "--prefix-repetition-prefix-len",
        type=int,
        default=None,
        help="Number of prefix tokens per request, used only for prefix "
        "repetition dataset.",
    )
    parser.add_argument(
        "--prefix-repetition-suffix-len",
        type=int,
        default=None,
        help="Number of suffix tokens per request, used only for prefix "
        "repetition dataset. Total input length is prefix_len + suffix_len.",
    )
    parser.add_argument(
        "--prefix-repetition-num-prefixes",
        type=int,
        default=None,
        help="Number of prefixes to generate, used only for prefix repetition "
        "dataset. Prompts per prefix is num_requests // num_prefixes.",
    )
    parser.add_argument(
        "--prefix-repetition-output-len",
        type=int,
        default=None,
        help="Number of output tokens per request, used only for prefix "
        "repetition dataset.",
    )

    # (random, random-mm, random-rerank)
    add_random_dataset_base_args(parser)
    add_random_multimodal_dataset_args(parser)

    parser = AsyncEngineArgs.add_cli_args(parser)

def filter_requests_for_dp(requests, data_parallel_size):
    # Note(zhuohan): The way we get data_parallel_rank is hacky and only
    # works for external launcher mode. Should be cleaned up and deprecated
    # in the future with a better vLLM distributed process design.
    if data_parallel_size == 1:
        return requests

    global_rank = int(os.environ["RANK"])
    world_size = int(os.environ["WORLD_SIZE"])
    data_parallel_rank = global_rank // (world_size // data_parallel_size)
    return [
        r
        for i, r in enumerate(requests)
        if i % data_parallel_size == data_parallel_rank
    ]

def get_requests(args, tokenizer):
    # Common parameters for all dataset types.
    common_kwargs = {
        "dataset_path": args.dataset_path,
        "random_seed": args.seed,
    }
    sample_kwargs = {
        "tokenizer": tokenizer,
        "lora_path": args.lora_path,
        "max_loras": args.max_loras,
        "num_requests": args.num_prompts,
    }

    if args.dataset_name == "random" or (
        args.dataset_path is None
        and args.dataset_name not in {"prefix_repetition", "random-mm", "random-rerank"}
    ):
        sample_kwargs["range_ratio"] = args.random_range_ratio
        # prefer random_* arguments, fall back to regular arguments
        random_prefix_len = getattr(args, "random_prefix_len", None)
        sample_kwargs["prefix_len"] = (
            random_prefix_len if random_prefix_len is not None else args.prefix_len
        )
        random_input_len = getattr(args, "random_input_len", None)
        sample_kwargs["input_len"] = (
            random_input_len if random_input_len is not None else args.input_len
        )
        random_output_len = getattr(args, "random_output_len", None)
        sample_kwargs["output_len"] = (
            random_output_len if random_output_len is not None else args.output_len
        )
        dataset_cls = RandomDataset
    elif args.dataset_name == "sharegpt":
        dataset_cls = ShareGPTDataset
        if args.backend == "vllm-chat":
            sample_kwargs["enable_multimodal_chat"] = True
        if args.output_len is not None:
            sample_kwargs["output_len"] = args.output_len
    elif args.dataset_name == "sonnet":
        assert tokenizer.chat_template or tokenizer.default_chat_template, (
            "Tokenizer/model must have chat template for sonnet dataset."
        )
        dataset_cls = SonnetDataset
        sample_kwargs["prefix_len"] = args.prefix_len
        sample_kwargs["return_prompt_formatted"] = True
        if args.input_len is not None:
            sample_kwargs["input_len"] = args.input_len
        if args.output_len is not None:
            sample_kwargs["output_len"] = args.output_len
    elif args.dataset_name == "burstgpt":
        dataset_cls = BurstGPTDataset
    elif args.dataset_name == "hf":
        if args.output_len is not None:
            sample_kwargs["output_len"] = args.output_len
        if args.dataset_path in VisionArenaDataset.SUPPORTED_DATASET_PATHS:
            dataset_cls = VisionArenaDataset
            common_kwargs["dataset_subset"] = None
            common_kwargs["dataset_split"] = "train"
            sample_kwargs["enable_multimodal_chat"] = True
        elif args.dataset_path in InstructCoderDataset.SUPPORTED_DATASET_PATHS:
            dataset_cls = InstructCoderDataset
            common_kwargs["dataset_split"] = "train"
        elif args.dataset_path in MultiModalConversationDataset.SUPPORTED_DATASET_PATHS:
            dataset_cls = MultiModalConversationDataset
            common_kwargs["dataset_subset"] = args.hf_subset
            common_kwargs["dataset_split"] = args.hf_split
            sample_kwargs["enable_multimodal_chat"] = True
        elif args.dataset_path in ConversationDataset.SUPPORTED_DATASET_PATHS:
            dataset_cls = ConversationDataset
            common_kwargs["dataset_subset"] = args.hf_subset
            common_kwargs["dataset_split"] = args.hf_split
            sample_kwargs["enable_multimodal_chat"] = True
        elif args.dataset_path in AIMODataset.SUPPORTED_DATASET_PATHS:
            dataset_cls = AIMODataset
            common_kwargs["dataset_subset"] = None
            common_kwargs["dataset_split"] = "train"
    elif args.dataset_name == "prefix_repetition":
        dataset_cls = PrefixRepetitionRandomDataset
        sample_kwargs["prefix_len"] = args.prefix_repetition_prefix_len
        sample_kwargs["suffix_len"] = args.prefix_repetition_suffix_len
        sample_kwargs["num_prefixes"] = args.prefix_repetition_num_prefixes
        sample_kwargs["output_len"] = args.prefix_repetition_output_len
    elif args.dataset_name == "random-mm":
        dataset_cls = RandomMultiModalDataset
        # prefer random_* arguments, fall back to regular arguments
        random_input_len = getattr(args, "random_input_len", None)
        sample_kwargs["input_len"] = (
            random_input_len
            if random_input_len is not None
            else getattr(args, "input_len", None)
        )
        random_output_len = getattr(args, "random_output_len", None)
        sample_kwargs["output_len"] = (
            random_output_len
            if random_output_len is not None
            else getattr(args, "output_len", None)
        )
        sample_kwargs["base_items_per_request"] = getattr(
            args, "random_mm_base_items_per_request", None
        )
        sample_kwargs["num_mm_items_range_ratio"] = getattr(
            args, "random_mm_num_mm_items_range_ratio", None
        )
        sample_kwargs["limit_mm_per_prompt"] = getattr(
            args, "random_mm_limit_mm_per_prompt", None
        )
        sample_kwargs["bucket_config"] = getattr(args, "random_mm_bucket_config", None)
        sample_kwargs["enable_multimodal_chat"] = True
        random_prefix_len = getattr(args, "random_prefix_len", None)
        prefix_len = getattr(args, "prefix_len", None)
        sample_kwargs["prefix_len"] = (
            random_prefix_len if random_prefix_len is not None else prefix_len
        )
        sample_kwargs["range_ratio"] = args.random_range_ratio
    elif args.dataset_name == "random-rerank":
        dataset_cls = RandomDatasetForReranking
        # prefer random_* arguments, fall back to regular arguments
        random_input_len = getattr(args, "random_input_len", None)
        sample_kwargs["input_len"] = (
            random_input_len
            if random_input_len is not None
            else getattr(args, "input_len", None)
        )
        random_output_len = getattr(args, "random_output_len", None)
        sample_kwargs["output_len"] = (
            random_output_len
            if random_output_len is not None
            else getattr(args, "output_len", None)
        )
        sample_kwargs["batchsize"] = getattr(args, "random_batch_size", 1)
        sample_kwargs["is_reranker"] = not getattr(args, "no_reranker", False)
        sample_kwargs["range_ratio"] = args.random_range_ratio
    else:
        raise ValueError(f"Unknown dataset name: {args.dataset_name}")
    # Remove None values
    sample_kwargs = {k: v for k, v in sample_kwargs.items() if v is not None}
    requests = dataset_cls(**common_kwargs).sample(**sample_kwargs)
    requests = filter_requests_for_dp(requests, args.data_parallel_size)
    return requests

def main(args: argparse.Namespace):
    validate_args(args)
    if args.seed is None:
        args.seed = 0
    random.seed(args.seed)
    # Sample the requests.
    if (
        args.backend == "hf" or args.backend == "mii"
    ) and args.tokenizer_mode == "auto":
        # mistral_common tokenizer is only supported on vllm and vllm-chat backends;
        # for hf and mii backends, we use hf tokenizer
        args.tokenizer_mode = "hf"
    tokenizer = get_tokenizer(
        args.tokenizer,
        tokenizer_mode=args.tokenizer_mode,
        trust_remote_code=args.trust_remote_code,
    )
    requests = get_requests(args, tokenizer)
    is_multi_modal = any(request.multi_modal_data is not None for request in requests)
    request_outputs: list[RequestOutput] | None = None
    if args.backend == "vllm":
        if args.async_engine:
            elapsed_time = uvloop.run(
                run_vllm_async(
                    requests,
                    args.n,
                    AsyncEngineArgs.from_cli_args(args),
                    disable_frontend_multiprocessing=args.disable_frontend_multiprocessing,
                    disable_detokenize=args.disable_detokenize,
                    do_profile=args.profile,
                )
            )
        else:
            elapsed_time, request_outputs = run_vllm(
                requests,
                args.n,
                EngineArgs.from_cli_args(args),
                disable_detokenize=args.disable_detokenize,
                do_profile=args.profile,
            )
    elif args.backend == "hf":
        assert args.tensor_parallel_size == 1
        if args.profile:
            raise NotImplementedError("Profiling not implemented yet for backend='hf'.")
        elapsed_time = run_hf(
            requests,
            args.model,
            tokenizer,
            args.n,
            args.hf_max_batch_size,
            args.trust_remote_code,
            args.disable_detokenize,
        )
    elif args.backend == "vllm-chat":
        elapsed_time, request_outputs = run_vllm_chat(
            requests,
            args.n,
            EngineArgs.from_cli_args(args),
            disable_detokenize=args.disable_detokenize,
            do_profile=args.profile,
        )
    else:
        raise ValueError(f"Unknown backend: {args.backend}")

    if request_outputs:
        # Note: with the vllm and vllm-chat backends,
        # we have request_outputs, which we use to count tokens.
        total_prompt_tokens = 0
        total_output_tokens = 0
        for ro in request_outputs:
            if not isinstance(ro, RequestOutput):
                continue
            total_prompt_tokens += (
                len(ro.prompt_token_ids) if ro.prompt_token_ids else 0
            )
            total_output_tokens += sum(len(o.token_ids) for o in ro.outputs if o)
        total_num_tokens = total_prompt_tokens + total_output_tokens
    else:
        total_num_tokens = sum(r.prompt_len + r.expected_output_len for r in requests)
        total_output_tokens = sum(r.expected_output_len for r in requests)
        total_prompt_tokens = total_num_tokens - total_output_tokens

    if is_multi_modal and args.backend != "vllm-chat":
        print(
            "\033[91mWARNING\033[0m: Multi-modal request with "
            f"{args.backend} backend detected. The "
            "following metrics are not accurate because image tokens are not"
            " counted. See vllm-project/vllm/issues/9778 for details."
        )
        # TODO(vllm-project/vllm/issues/9778): Count multi-modal token length.
        # vllm-chat backend counts the image tokens now

    print(
        f"Throughput: {len(requests) / elapsed_time:.2f} requests/s, "
        f"{total_num_tokens / elapsed_time:.2f} total tokens/s, "
        f"{total_output_tokens / elapsed_time:.2f} output tokens/s"
    )
    print(f"Total num prompt tokens:  {total_prompt_tokens}")
    print(f"Total num output tokens:  {total_output_tokens}")

    # Output JSON results if specified
    if args.output_json:
        results = {
            "elapsed_time": elapsed_time,
            "num_requests": len(requests),
            "total_num_tokens": total_num_tokens,
            "requests_per_second": len(requests) / elapsed_time,
            "tokens_per_second": total_num_tokens / elapsed_time,
        }
        with open(args.output_json, "w") as f:
            json.dump(results, f, indent=4)
        save_to_pytorch_benchmark_format(args, results)

def run_hf(
    requests: list[SampleRequest],
    model: str,
    tokenizer: TokenizerLike,
    n: int,
    max_batch_size: int,
    trust_remote_code: bool,
    disable_detokenize: bool = False,
) -> float:
    assert isinstance(tokenizer, PreTrainedTokenizerBase), (
        "the hf backend only supports HF tokenizers"
    )
    llm = AutoModelForCausalLM.from_pretrained(
        model, dtype=torch.float16, trust_remote_code=trust_remote_code
    )
    if llm.config.model_type == "llama":
        # To enable padding in the HF backend.
        tokenizer.pad_token = tokenizer.eos_token
    llm = llm.cuda()

    pbar = tqdm(total=len(requests))
    start = time.perf_counter()
    batch: list[str] = []
    max_prompt_len = 0
    max_output_len = 0
    for i in range(len(requests)):
        prompt = requests[i].prompt
        prompt_len = requests[i].prompt_len
        output_len = requests[i].expected_output_len
        # Add the prompt to the batch.
        batch.append(prompt)
        max_prompt_len = max(max_prompt_len, prompt_len)
        max_output_len = max(max_output_len, output_len)
        if len(batch) < max_batch_size and i != len(requests) - 1:
            # Check if we can add more requests to the batch.
            next_prompt_len = requests[i + 1].prompt_len
            next_output_len = requests[i + 1].expected_output_len
            if (
                max(max_prompt_len, next_prompt_len)
                + max(max_output_len, next_output_len)
            ) <= 2048:
                # We can add more requests to the batch.
                continue

        # Generate the sequences.
        input_ids = tokenizer(batch, return_tensors="pt", padding=True).input_ids
        llm_outputs = llm.generate(
            input_ids=input_ids.cuda(),
            do_sample=True,
            num_return_sequences=n,
            temperature=1.0,
            top_p=1.0,
            use_cache=True,
            max_new_tokens=max_output_len,
        )
        if not disable_detokenize:
            # Include the decoding time.
            tokenizer.batch_decode(llm_outputs, skip_special_tokens=True)
        pbar.update(len(batch))

        # Clear the batch.
        batch = []
        max_prompt_len = 0
        max_output_len = 0
    end = time.perf_counter()
    return end - start

def run_vllm(
    requests: list[SampleRequest],
    n: int,
    engine_args: EngineArgs,
    do_profile: bool,
    disable_detokenize: bool = False,
) -> tuple[float, list[RequestOutput] | None]:
    from vllm import LLM, SamplingParams

    llm = LLM(**dataclasses.asdict(engine_args))
    assert all(
        llm.llm_engine.model_config.max_model_len
        >= (request.prompt_len + request.expected_output_len)
        for request in requests
    ), (
        "Please ensure that max_model_len is greater than the sum of"
        " prompt_len and expected_output_len for all requests."
    )
    # Add the requests to the engine.
    prompts: list[TextPrompt | TokensPrompt] = []
    sampling_params: list[SamplingParams] = []
    for request in requests:
        prompt = (
            TokensPrompt(prompt_token_ids=request.prompt["prompt_token_ids"])
            if "prompt_token_ids" in request.prompt
            else TextPrompt(prompt=request.prompt)
        )
        if request.multi_modal_data:
            assert isinstance(request.multi_modal_data, dict)
            prompt["multi_modal_data"] = request.multi_modal_data
        prompts.append(prompt)

        sampling_params.append(
            SamplingParams(
                n=n,
                temperature=1.0,
                top_p=1.0,
                ignore_eos=True,
                max_tokens=request.expected_output_len,
                detokenize=not disable_detokenize,
            )
        )
    lora_requests: list[LoRARequest] | None = None
    if engine_args.enable_lora:
        lora_requests = [request.lora_request for request in requests]

    use_beam_search = False

    outputs = None
    if not use_beam_search:
        start = time.perf_counter()
        if do_profile:
            llm.start_profile()
        outputs = llm.generate(
            prompts, sampling_params, lora_request=lora_requests, use_tqdm=True
        )
        if do_profile:
            llm.stop_profile()
        end = time.perf_counter()
    else:
        assert lora_requests is None, "BeamSearch API does not support LoRA"
        prompts = [request.prompt for request in requests]
        # output_len should be the same for all requests.
        output_len = requests[0].expected_output_len
        for request in requests:
            assert request.expected_output_len == output_len
        start = time.perf_counter()
        if do_profile:
            llm.start_profile()
        llm.beam_search(
            prompts,
            BeamSearchParams(
                beam_width=n,
                max_tokens=output_len,
                ignore_eos=True,
            ),
        )
        if do_profile:
            llm.stop_profile()
        end = time.perf_counter()
    return end - start, outputs

async def run_vllm_async(
    requests: list[SampleRequest],
    n: int,
    engine_args: AsyncEngineArgs,
    do_profile: bool,
    disable_frontend_multiprocessing: bool = False,
    disable_detokenize: bool = False,
) -> float:
    from vllm import SamplingParams
    from vllm.entrypoints.openai.api_server import (
        build_async_engine_client_from_engine_args,
    )

    async with build_async_engine_client_from_engine_args(
        engine_args,
        disable_frontend_multiprocessing=disable_frontend_multiprocessing,
    ) as llm:
        model_config = llm.model_config
        assert all(
            model_config.max_model_len
            >= (request.prompt_len + request.expected_output_len)
            for request in requests
        ), (
            "Please ensure that max_model_len is greater than the sum of"
            " prompt_len and expected_output_len for all requests."
        )

        # Add the requests to the engine.
        prompts: list[TextPrompt | TokensPrompt] = []
        sampling_params: list[SamplingParams] = []
        lora_requests: list[LoRARequest | None] = []
        for request in requests:
            prompt = (
                TokensPrompt(prompt_token_ids=request.prompt["prompt_token_ids"])
                if "prompt_token_ids" in request.prompt
                else TextPrompt(prompt=request.prompt)
            )

            if request.multi_modal_data:
                assert isinstance(request.multi_modal_data, dict)
                prompt["multi_modal_data"] = request.multi_modal_data

            sampling_params.append(
                SamplingParams(
                    n=n,
                    temperature=1.0,
                    top_p=1.0,
                    ignore_eos=True,
                    max_tokens=request.expected_output_len,
                    detokenize=not disable_detokenize,
                )
            )
            prompts.append(prompt)
            lora_requests.append(request.lora_request)

        generators = []
        start = time.perf_counter()
        if do_profile:
            await llm.start_profile()
        for i, (prompt, sp, lr) in enumerate(
            zip(prompts, sampling_params, lora_requests)
        ):
            generator = llm.generate(prompt, sp, lora_request=lr, request_id=f"test{i}")
            generators.append(generator)
        all_gens = merge_async_iterators(*generators)
        async for i, res in all_gens:
            pass
        if do_profile:
            await llm.stop_profile()
        end = time.perf_counter()
        return end - start

def run_vllm_chat(
    requests: list[SampleRequest],
    n: int,
    engine_args: EngineArgs,
    do_profile: bool,
    disable_detokenize: bool = False,
) -> tuple[float, list[RequestOutput]]:
    """
    Run vLLM chat benchmark. This function is recommended ONLY for benchmarking
    multimodal models as it properly handles multimodal inputs and chat
    formatting. For non-multimodal models, use run_vllm() instead.
    """
    from vllm import LLM, SamplingParams

    llm = LLM(**dataclasses.asdict(engine_args))

    assert all(
        llm.llm_engine.model_config.max_model_len
        >= (request.prompt_len + request.expected_output_len)
        for request in requests
    ), (
        "Please ensure that max_model_len is greater than the sum of "
        "prompt_len and expected_output_len for all requests."
    )

    prompts = []
    sampling_params: list[SamplingParams] = []
    for request in requests:
        prompts.append(request.prompt)
        sampling_params.append(
            SamplingParams(
                n=n,
                temperature=1.0,
                top_p=1.0,
                ignore_eos=True,
                max_tokens=request.expected_output_len,
                detokenize=not disable_detokenize,
            )
        )
    start = time.perf_counter()
    if do_profile:
        llm.start_profile()
    outputs = llm.chat(prompts, sampling_params, use_tqdm=True)
    if do_profile:
        llm.stop_profile()
    end = time.perf_counter()
    return end - start, outputs

def save_to_pytorch_benchmark_format(
    args: argparse.Namespace, results: dict[str, Any]
) -> None:
    pt_records = convert_to_pytorch_benchmark_format(
        args=args,
        metrics={
            "requests_per_second": [results["requests_per_second"]],
            "tokens_per_second": [results["tokens_per_second"]],
        },
        extra_info={
            k: results[k] for k in ["elapsed_time", "num_requests", "total_num_tokens"]
        },
    )
    if pt_records:
        # Don't use json suffix here as we don't want CI to pick it up
        pt_file = f"{os.path.splitext(args.output_json)[0]}.pytorch.json"
        write_to_json(pt_file, pt_records)

def validate_args(args):
    """
    Validate command-line arguments.
    """

    # === Deprecation and Defaulting ===
    if args.dataset is not None:
        warnings.warn(
            "The '--dataset' argument will be deprecated in the next release. "
            "Please use '--dataset-name' and '--dataset-path' instead.",
            stacklevel=2,
        )
        args.dataset_path = args.dataset

    if not getattr(args, "tokenizer", None):
        args.tokenizer = args.model

    # === Backend Validation ===
    valid_backends = {"vllm", "hf", "mii", "vllm-chat"}
    if args.backend not in valid_backends:
        raise ValueError(f"Unsupported backend: {args.backend}")

    # === Dataset Configuration ===
    if (
        not args.dataset
        and not args.dataset_path
        and args.dataset_name not in {"prefix_repetition"}
    ):
        print("When dataset path is not set, it will default to random dataset")
        args.dataset_name = "random"
        random_input_len = getattr(args, "random_input_len", None)
        if args.input_len is None and random_input_len is None:
            raise ValueError(
                "Either --input-len or --random-input-len must be provided "
                "for a random dataset"
            )

    # === Dataset Name Specific Checks ===
    # --hf-subset and --hf-split: only used
    # when dataset_name is 'hf'
    if args.dataset_name != "hf" and (
        getattr(args, "hf_subset", None) is not None
        or getattr(args, "hf_split", None) is not None
    ):
        warnings.warn(
            "--hf-subset and --hf-split will be ignored \
                since --dataset-name is not 'hf'.",
            stacklevel=2,
        )
    elif args.dataset_name == "hf":
        if args.dataset_path in (
            VisionArenaDataset.SUPPORTED_DATASET_PATHS.keys()
            | MultiModalConversationDataset.SUPPORTED_DATASET_PATHS
            | ConversationDataset.SUPPORTED_DATASET_PATHS
        ):
            assert args.backend == "vllm-chat", (
                f"{args.dataset_path} needs to use vllm-chat as the backend."
            )
        elif args.dataset_path in (
            InstructCoderDataset.SUPPORTED_DATASET_PATHS
            | AIMODataset.SUPPORTED_DATASET_PATHS
        ):
            assert args.backend == "vllm", (
                f"{args.dataset_path} needs to use vllm as the backend."
            )
        else:
            raise ValueError(f"{args.dataset_path} is not supported by hf dataset.")

    # --random-range-ratio: only used when dataset_name is 'random',
    # 'random-mm', or 'random-rerank'
    if (
        args.dataset_name not in {"random", "random-mm", "random-rerank"}
        and args.random_range_ratio is not None
    ):
        warnings.warn(
            "--random-range-ratio will be ignored since \
                --dataset-name is not 'random', 'random-mm', or 'random-rerank'.",
            stacklevel=2,
        )

    # --random-batch-size: only used when dataset_name is 'random-rerank'
    if (
        args.dataset_name != "random-rerank"
        and getattr(args, "random_batch_size", None) is not None
    ) and args.random_batch_size != 1:
        warnings.warn(
            "--random-batch-size will be ignored since \
                    --dataset-name is not 'random-rerank'.",
            stacklevel=2,
        )

    # --no-reranker: only used when dataset_name is 'random-rerank'
    if args.dataset_name != "random-rerank" and getattr(args, "no_reranker", False):
        warnings.warn(
            "--no-reranker will be ignored since \
                --dataset-name is not 'random-rerank'.",
            stacklevel=2,
        )

    # --prefix-len: only used when dataset_name is 'random', 'random-mm',
    # 'sonnet', or not set.
    if (
        args.dataset_name not in {"random", "random-mm", "sonnet", None}
        and args.prefix_len is not None
    ):
        warnings.warn(
            "--prefix-len will be ignored since --dataset-name\
                 is not 'random', 'random-mm', 'sonnet', or not set.",
            stacklevel=2,
        )

    # === Random Dataset Argument Conflict Detection ===
    # Check for conflicts between regular and random arguments when using
    # random datasets
    if args.dataset_name in {"random", "random-mm", "random-rerank"}:
        random_input_len = getattr(args, "random_input_len", None)
        random_output_len = getattr(args, "random_output_len", None)
        random_prefix_len = getattr(args, "random_prefix_len", None)

        if args.input_len is not None and random_input_len is not None:
            warnings.warn(
                "Both --input-len and --random-input-len are specified. "
                "The random version (--random-input-len) will be preferred "
                "in this run.",
                stacklevel=2,
            )
        if args.output_len is not None and random_output_len is not None:
            warnings.warn(
                "Both --output-len and --random-output-len are specified. "
                "The random version (--random-output-len) will be preferred "
                "in this run.",
                stacklevel=2,
            )
        if args.prefix_len is not None and random_prefix_len is not None:
            warnings.warn(
                "Both --prefix-len and --random-prefix-len are specified. "
                "The random version (--random-prefix-len) will be preferred "
                "in this run.",
                stacklevel=2,
            )

    # === LoRA Settings ===
    if getattr(args, "enable_lora", False) and args.backend != "vllm":
        raise ValueError("LoRA benchmarking is only supported for vLLM backend")
    if getattr(args, "enable_lora", False) and args.lora_path is None:
        raise ValueError("LoRA path must be provided when enable_lora is True")

    # === Backend-specific Validations ===
    if args.backend == "hf" and args.hf_max_batch_size is None:
        raise ValueError("HF max batch size is required for HF backend")
    if args.backend != "hf" and args.hf_max_batch_size is not None:
        raise ValueError("HF max batch size is only for HF backend.")

    if (
        args.backend in {"hf", "mii"}
        and getattr(args, "quantization", None) is not None
    ):
        raise ValueError("Quantization is only for vLLM backend.")

    if args.backend == "mii" and args.dtype != "auto":
        raise ValueError("dtype must be auto for MII backend.")
    if args.backend == "mii" and args.n != 1:
        raise ValueError("n must be 1 for MII backend.")
    if args.backend == "mii" and args.tokenizer != args.model:
        raise ValueError("Tokenizer must be the same as the model for MII backend.")

    if args.data_parallel_size > 1 and (
        args.distributed_executor_backend != "external_launcher" or args.async_engine
    ):
        # --data-parallel is not supported fully.
        # Old issue: https://github.com/vllm-project/vllm/issues/16222
        # Currently we only support data parallel with external launcher
        # mode (i.e., launch with toruchrun).
        raise ValueError(
            "Data parallel is only supported with external launcher mode "
            "with synchronous engine in offline benchmark, "
            "please use benchmark serving instead"
        )