Add `pt_load_map_location` to allow loading to cuda (#16869)

Signed-off-by: Jerry Zhang <jerryzh168@gmail.com>

tests/quantization/test_torchao.py

@@ -3,6 +3,7 @@ import importlib.metadata
 import importlib.util
 
 import pytest
+import torch
 
 DTYPE = ["bfloat16"]
 
@@ -21,5 +22,30 @@ def test_pre_quantized_model(vllm_runner):
     print(output)
 
 
+@pytest.mark.skipif(not TORCHAO_AVAILABLE, reason="torchao is not available")
+@pytest.mark.parametrize(
+    "pt_load_map_location",
+    [
+        "cuda:0",
+        # {"": "cuda"},
+    ])
+def test_opt_125m_int4wo_model_loading_with_params(vllm_runner,
+                                                   pt_load_map_location):
+    """
+    Test loading roberta-base model with no lm_head.
+    """
+    torch._dynamo.reset()
+    model_name = "jerryzh168/opt-125m-int4wo"
+    with vllm_runner(model_name=model_name,
+                     quantization="torchao",
+                     dtype="bfloat16",
+                     pt_load_map_location=pt_load_map_location) as llm:
+        output = llm.generate_greedy(["The capital of France is"],
+                                     max_tokens=32)
+
+        assert output
+        print(output)
+
+
 if __name__ == "__main__":
     pytest.main([__file__])

tests/test_config.py

@@ -5,7 +5,8 @@ from typing import Literal, Union
 
 import pytest
 
-from vllm.config import ModelConfig, PoolerConfig, config, get_field
+from vllm.config import (LoadConfig, ModelConfig, PoolerConfig, VllmConfig,
+                         config, get_field)
 from vllm.model_executor.layers.pooler import PoolingType
 from vllm.platforms import current_platform
 
@@ -410,3 +411,16 @@ def test_generation_config_loading():
         override_generation_config=override_generation_config)
 
     assert model_config.get_diff_sampling_param() == override_generation_config
+
+
+@pytest.mark.parametrize("pt_load_map_location", [
+    "cuda",
+    {
+        "": "cuda"
+    },
+])
+def test_load_config_pt_load_map_location(pt_load_map_location):
+    load_config = LoadConfig(pt_load_map_location=pt_load_map_location)
+    config = VllmConfig(load_config=load_config)
+
+    assert config.load_config.pt_load_map_location == pt_load_map_location

vllm/config.py

@@ -1564,6 +1564,16 @@ class LoadConfig:
     use_tqdm_on_load: bool = True
     """Whether to enable tqdm for showing progress bar when loading model
     weights."""
+    pt_load_map_location: Union[str, dict[str, str]] = "cpu"
+    """
+    pt_load_map_location: the map location for loading pytorch checkpoint, to
+    support loading checkpoints can only be loaded on certain devices like
+    "cuda", this is equivalent to {"": "cuda"}. Another supported format is
+    mapping from different devices like from GPU 1 to GPU 0:
+    {"cuda:1": "cuda:0"}. Note that when passed from command line, the strings
+    in dictionary needs to be double quoted for json parsing. For more details,
+    see original doc for `map_location` in https://pytorch.org/docs/stable/generated/torch.load.html
+    """
 
     def compute_hash(self) -> str:
         """

vllm/engine/arg_utils.py

@@ -64,6 +64,13 @@ def optional_type(
     return _optional_type
 
 
+def union_dict_and_str(val: str) -> Optional[Union[str, dict[str, str]]]:
+    if not re.match("^{.*}$", val):
+        return str(val)
+    else:
+        return optional_type(json.loads)(val)
+
+
 @deprecated(
     "Passing a JSON argument as a string containing comma separated key=value "
     "pairs is deprecated. This will be removed in v0.10.0. Please use a JSON "
@@ -187,6 +194,10 @@ def get_kwargs(cls: ConfigType) -> dict[str, Any]:
                 kwargs[name]["type"] = human_readable_int
         elif contains_type(type_hints, float):
             kwargs[name]["type"] = float
+        elif contains_type(type_hints,
+                           dict) and (contains_type(type_hints, str) or any(
+                               is_not_builtin(th) for th in type_hints)):
+            kwargs[name]["type"] = union_dict_and_str
         elif contains_type(type_hints, dict):
             # Dict arguments will always be optional
             kwargs[name]["type"] = optional_type(json.loads)
@@ -371,6 +382,7 @@ class EngineArgs:
     reasoning_parser: str = DecodingConfig.reasoning_backend
 
     use_tqdm_on_load: bool = LoadConfig.use_tqdm_on_load
+    pt_load_map_location: str = LoadConfig.pt_load_map_location
 
     def __post_init__(self):
         # support `EngineArgs(compilation_config={...})`
@@ -491,6 +503,8 @@ class EngineArgs:
                                 type=str,
                                 default=None,
                                 help='Name or path of the QLoRA adapter.')
+        load_group.add_argument('--pt-load-map-location',
+                                **load_kwargs["pt_load_map_location"])
 
         # Guided decoding arguments
         guided_decoding_kwargs = get_kwargs(DecodingConfig)
@@ -883,12 +897,14 @@ class EngineArgs:
 
         if self.quantization == "bitsandbytes":
             self.load_format = "bitsandbytes"
+
         return LoadConfig(
             load_format=self.load_format,
             download_dir=self.download_dir,
             model_loader_extra_config=self.model_loader_extra_config,
             ignore_patterns=self.ignore_patterns,
             use_tqdm_on_load=self.use_tqdm_on_load,
+            pt_load_map_location=self.pt_load_map_location,
         )
 
     def create_speculative_config(
@@ -1513,7 +1529,7 @@ def _warn_or_fallback(feature_name: str) -> bool:
 def human_readable_int(value):
     """Parse human-readable integers like '1k', '2M', etc.
     Including decimal values with decimal multipliers.
-    
+
     Examples:
     - '1k' -> 1,000
     - '1K' -> 1,024

vllm/model_executor/model_loader/loader.py

@@ -384,6 +384,7 @@ class DefaultModelLoader(BaseModelLoader):
             weights_iterator = pt_weights_iterator(
                 hf_weights_files,
                 self.load_config.use_tqdm_on_load,
+                self.load_config.pt_load_map_location,
             )
 
         if current_platform.is_tpu():
@@ -890,6 +891,7 @@ class BitsAndBytesModelLoader(BaseModelLoader):
             iterator = pt_weights_iterator(
                 hf_weights_files,
                 self.load_config.use_tqdm_on_load,
+                self.load_config.pt_load_map_location,
             )
         for org_name, param in iterator:
             # mapping weight names from transformers to vllm while preserving

vllm/model_executor/model_loader/weight_utils.py

@@ -502,6 +502,7 @@ def fastsafetensors_weights_iterator(
 def pt_weights_iterator(
     hf_weights_files: List[str],
     use_tqdm_on_load: bool,
+    pt_load_map_location: Union[str, dict[str, str]] = "cpu",
 ) -> Generator[Tuple[str, torch.Tensor], None, None]:
     """Iterate over the weights in the model bin/pt files."""
     for bin_file in tqdm(
@@ -510,7 +511,9 @@ def pt_weights_iterator(
             disable=not enable_tqdm(use_tqdm_on_load),
             bar_format=_BAR_FORMAT,
     ):
-        state = torch.load(bin_file, map_location="cpu", weights_only=True)
+        state = torch.load(bin_file,
+                           map_location=pt_load_map_location,
+                           weights_only=True)
         yield from state.items()
         del state