Add support for a rope extension method (#6553)

vllm/config.py

@@ -151,6 +151,15 @@ class ModelConfig:
         self.hf_text_config = get_hf_text_config(self.hf_config)
         self.dtype = _get_and_verify_dtype(self.hf_text_config, dtype)
 
+        if (getattr(self.hf_config, "max_position_embeddings", 0) == 131072
+                and getattr(self.hf_config, "rope_scaling", None) is None):
+            # Note(simon): this is a special case for a model that doesn't
+            # supply rope_scaling. We should remove this once the model is
+            # updated.
+            self.hf_config.update({"rope_scaling": {
+                "type": "extended",
+            }})
+
         if (not self.disable_sliding_window
                 and self.hf_text_config.model_type == "gemma2"
                 and self.hf_text_config.sliding_window is not None):
@@ -1442,8 +1451,9 @@ def _get_and_verify_max_len(
     rope_scaling = getattr(hf_config, "rope_scaling", None)
     # The correct one should be "longrope", kept "su" here
     # to be backward compatible
-    if rope_scaling is not None and rope_scaling["type"] != "su" \
-        and rope_scaling["type"] != "longrope":
+    if rope_scaling is not None and rope_scaling["type"] not in {
+            "su", "longrope", "extended"
+    }:
         if disable_sliding_window:
             # TODO(robertgshaw): Find a model that supports rope_scaling
             # with sliding window to see if this case should be allowed.