[Model] Add FP8 kv cache for Qwen2 (vllm-project#5656)

vllm/model_executor/models/qwen2.py

@@ -46,6 +46,7 @@
 from vllm.model_executor.model_loader.weight_utils import default_weight_loader
 from vllm.model_executor.sampling_metadata import SamplingMetadata
 from vllm.sequence import SamplerOutput
+from vllm.utils import print_warning_once
 
 
 class Qwen2MLP(nn.Module):
@@ -375,6 +376,19 @@ def load_weights(self, weights: Iterable[Tuple[str, torch.Tensor]]):
                 # Skip loading extra bias for GPTQ models.
                 if name.endswith(".bias") and name not in params_dict:
                     continue
+                # Remapping the name of FP8 kv-scale.
+                if name.endswith("kv_scale"):
+                    remapped_kv_scale_name = name.replace(
+                        ".kv_scale", ".attn.kv_scale")
+                    if remapped_kv_scale_name not in params_dict:
+                        print_warning_once(
+                            f"Found kv scale in the checkpoint (e.g. {name}), "
+                            "but not found the expected name in the model "
+                            f"(e.g. {remapped_kv_scale_name}). kv-scale is "
+                            "not loaded.")
+                        continue
+                    else:
+                        name = remapped_kv_scale_name
                 param = params_dict[name]
                 weight_loader = getattr(param, "weight_loader",
                                         default_weight_loader)