[RL] Support per-layer mixed FP8/BF16 serving for FP8 checkpoints (#18742)

python/sglang/srt/layers/quantization/fp8.py

@@ -60,7 +60,10 @@ from sglang.srt.layers.quantization.marlin_utils_fp8 import (
     apply_fp8_marlin_linear,
     prepare_fp8_layer_for_marlin,
 )
-from sglang.srt.layers.quantization.unquant import UnquantizedLinearMethod
+from sglang.srt.layers.quantization.unquant import (
+    UnquantizedFusedMoEMethod,
+    UnquantizedLinearMethod,
+)
 from sglang.srt.layers.quantization.utils import (
     all_close_1d,
     convert_to_channelwise,
@@ -117,8 +120,10 @@ class Fp8Config(QuantizationConfig):
         activation_scheme: str = "dynamic",
         ignored_layers: Optional[List[str]] = None,
         weight_block_size: List[int] = None,
+        packed_modules_mapping: Optional[Dict[str, List[str]]] = None,
         use_mxfp8: bool = False,
     ) -> None:
+        super().__init__()
         self.is_checkpoint_fp8_serialized = is_checkpoint_fp8_serialized
         if is_checkpoint_fp8_serialized:
             log_info_on_rank0(logger, "Detected fp8 checkpoint.")
@@ -126,6 +131,7 @@ class Fp8Config(QuantizationConfig):
             raise ValueError(f"Unsupported activation scheme {activation_scheme}")
         self.activation_scheme = activation_scheme
         self.ignored_layers = ignored_layers or []
+        self.packed_modules_mapping = packed_modules_mapping or {}
         self.use_mxfp8 = use_mxfp8
         if weight_block_size is not None:
             if not is_checkpoint_fp8_serialized:
@@ -167,15 +173,20 @@ class Fp8Config(QuantizationConfig):
         use_mxfp8 = "mxfp8" in quant_method
         is_checkpoint_fp8_serialized = ("fp8" in quant_method) or use_mxfp8
         activation_scheme = cls.get_from_keys(config, ["activation_scheme"])
+        packed_modules_mapping = (
+            cls.get_from_keys_or(config, ["packed_modules_mapping"], {}) or {}
+        )
         ignored_layers = cls.get_from_keys_or(
             config, ["ignored_layers", "modules_to_not_convert"], None
         )
         if ignored_layers:
-            if "mistral3" in config.get("model_type", ""):
-                # hack for ministral
-                ignored_layers = [
-                    layer.replace("model.", "") for layer in ignored_layers
-                ]
+            # Keep both "model." and non-"model." variants for robust prefix matching.
+            normalized = []
+            for layer in ignored_layers:
+                base = layer.removeprefix("model.")
+                normalized.append(base)
+                normalized.append(f"model.{base}")
+            ignored_layers = normalized
         weight_block_size = cls.get_from_keys_or(config, ["weight_block_size"], None)
         if use_mxfp8 and weight_block_size is not None:
             logger.warning(
@@ -187,6 +198,7 @@ class Fp8Config(QuantizationConfig):
             activation_scheme=activation_scheme,
             ignored_layers=ignored_layers,
             weight_block_size=weight_block_size,
+            packed_modules_mapping=packed_modules_mapping,
             use_mxfp8=use_mxfp8,
         )
 
@@ -198,10 +210,18 @@ class Fp8Config(QuantizationConfig):
         from sglang.srt.layers.radix_attention import RadixAttention
 
         if isinstance(layer, LinearBase):
-            if is_layer_skipped(prefix, self.ignored_layers):
+            if is_layer_skipped(
+                prefix, self.ignored_layers, fused_mapping=self.packed_modules_mapping
+            ):
                 return UnquantizedLinearMethod()
             return Fp8LinearMethod(self)
         elif isinstance(layer, FusedMoE):
+            if is_layer_skipped(
+                prefix, self.ignored_layers, fused_mapping=self.packed_modules_mapping
+            ):
+                return UnquantizedFusedMoEMethod(
+                    layer.use_triton_kernels, layer.use_flashinfer_trtllm_moe
+                )
             return Fp8MoEMethod(self)
         elif isinstance(layer, RadixAttention):
             return Fp8KVCacheMethod(self)

python/sglang/srt/layers/quantization/utils.py

@@ -84,12 +84,12 @@ def is_layer_skipped(
             if prefix_gate in ignored_layers and prefix_up in ignored_layers:
                 is_skipped = True
         elif "experts" in prefix:
-            is_skipped = any(
-                [
-                    prefix in layer_name
-                    for layer_name in ignored_layers
-                    if "experts" in layer_name
-                ]
+            # Expert names can include full module paths; keep coarse prefix matches
+            # (e.g., "model.layers.{i}.") while also checking expert-specific entries.
+            is_skipped = is_skipped or any(
+                prefix in layer_name
+                for layer_name in ignored_layers
+                if "experts" in layer_name
             )
 
     assert is_skipped is not None