[4/N] make quant config first-class citizen (#9978)

Signed-off-by: youkaichao <youkaichao@gmail.com>

vllm/config.py

@@ -23,9 +23,13 @@ if TYPE_CHECKING:
     from ray.util.placement_group import PlacementGroup
 
     from vllm.executor.executor_base import ExecutorBase
+    from vllm.model_executor.layers.quantization.base_config import (
+        QuantizationConfig)
     from vllm.model_executor.model_loader.loader import BaseModelLoader
     from vllm.transformers_utils.tokenizer_group.base_tokenizer_group import (
         BaseTokenizerGroup)
+else:
+    QuantizationConfig = None
 
 logger = init_logger(__name__)
 
@@ -1966,6 +1970,35 @@ class VllmConfig:
     decoding_config: Optional[DecodingConfig] = None
     observability_config: Optional[ObservabilityConfig] = None
     prompt_adapter_config: Optional[PromptAdapterConfig] = None
+    quant_config: Optional[QuantizationConfig] = None
+
+    @staticmethod
+    def _get_quantization_config(
+            model_config: ModelConfig,
+            load_config: LoadConfig) -> Optional[QuantizationConfig]:
+        """Get the quantization config."""
+        if model_config.quantization is not None:
+            from vllm.model_executor.model_loader.weight_utils import (
+                get_quant_config)
+            quant_config = get_quant_config(model_config, load_config)
+            capability_tuple = current_platform.get_device_capability()
+
+            if capability_tuple is not None:
+                capability = capability_tuple.to_int()
+                if capability < quant_config.get_min_capability():
+                    raise ValueError(
+                        f"The quantization method {model_config.quantization} "
+                        "is not supported for the current GPU. Minimum "
+                        f"capability: {quant_config.get_min_capability()}. "
+                        f"Current capability: {capability}.")
+            supported_dtypes = quant_config.get_supported_act_dtypes()
+            if model_config.dtype not in supported_dtypes:
+                raise ValueError(
+                    f"{model_config.dtype} is not supported for quantization "
+                    f"method {model_config.quantization}. Supported dtypes: "
+                    f"{supported_dtypes}")
+            return quant_config
+        return None
 
     def __post_init__(self):
         """Verify configs are valid & consistent with each other.
@@ -1983,3 +2016,8 @@ class VllmConfig:
         if self.prompt_adapter_config:
             self.prompt_adapter_config.verify_with_model_config(
                 self.model_config)
+
+        if self.quant_config is None and \
+            self.model_config is not None and self.load_config is not None:
+            self.quant_config = VllmConfig._get_quantization_config(
+                self.model_config, self.load_config)

vllm/model_executor/model_loader/loader.py

@@ -39,7 +39,7 @@ from vllm.model_executor.model_loader.utils import (get_model_architecture,
 from vllm.model_executor.model_loader.weight_utils import (
     download_safetensors_index_file_from_hf, download_weights_from_hf,
     filter_duplicate_safetensors_files, filter_files_not_needed_for_inference,
-    get_gguf_extra_tensor_names, get_quant_config, gguf_quant_weights_iterator,
+    get_gguf_extra_tensor_names, gguf_quant_weights_iterator,
     initialize_dummy_weights, np_cache_weights_iterator, pt_weights_iterator,
     safetensors_weights_iterator)
 from vllm.model_executor.models import (has_inner_state, supports_lora,
@@ -93,32 +93,6 @@ def device_loading_context(module: torch.nn.Module,
 logger = init_logger(__name__)
 
 
-def _get_quantization_config(
-        model_config: ModelConfig,
-        load_config: LoadConfig) -> Optional[QuantizationConfig]:
-    """Get the quantization config."""
-    if model_config.quantization is not None:
-        quant_config = get_quant_config(model_config, load_config)
-        capability_tuple = current_platform.get_device_capability()
-
-        if capability_tuple is not None:
-            capability = capability_tuple.to_int()
-            if capability < quant_config.get_min_capability():
-                raise ValueError(
-                    f"The quantization method {model_config.quantization} "
-                    "is not supported for the current GPU. "
-                    f"Minimum capability: {quant_config.get_min_capability()}. "
-                    f"Current capability: {capability}.")
-        supported_dtypes = quant_config.get_supported_act_dtypes()
-        if model_config.dtype not in supported_dtypes:
-            raise ValueError(
-                f"{model_config.dtype} is not supported for quantization "
-                f"method {model_config.quantization}. Supported dtypes: "
-                f"{supported_dtypes}")
-        return quant_config
-    return None
-
-
 def _get_model_initialization_kwargs(
         model_class: Type[nn.Module],
         lora_config: Optional[LoRAConfig],
@@ -185,7 +159,6 @@ def _initialize_model(vllm_config: VllmConfig) -> nn.Module:
     lora_config = vllm_config.lora_config
     scheduler_config = vllm_config.scheduler_config
     cache_config = vllm_config.cache_config
-    load_config = vllm_config.load_config
     model_class, _ = get_model_architecture(model_config)
 
     return build_model(
@@ -193,7 +166,7 @@ def _initialize_model(vllm_config: VllmConfig) -> nn.Module:
         vllm_config,
         model_config.hf_config,
         cache_config=cache_config,
-        quant_config=_get_quantization_config(model_config, load_config),
+        quant_config=vllm_config.quant_config,
         lora_config=lora_config,
         multimodal_config=model_config.multimodal_config,
         scheduler_config=scheduler_config,
@@ -518,8 +491,7 @@ class TensorizerLoader(BaseModelLoader):
         with set_default_torch_dtype(model_config.dtype):
             with torch.device(device_config.device):
                 model_class = get_model_architecture(model_config)[0]
-                quant_config = _get_quantization_config(
-                    model_config, self.load_config)
+                quant_config = vllm_config.quant_config
                 extra_kwargs = _get_model_initialization_kwargs(
                     model_class, lora_config, model_config.multimodal_config)
                 extra_kwargs["quant_config"] = quant_config