Support EPLB in FusedMoE (#8448)

Author: ch-wan

python/sglang/srt/eplb/expert_distribution.py

@@ -47,6 +47,11 @@ def init_new(
         rank: int,
     ):
         if server_args.expert_distribution_recorder_mode is not None:
+            assert (
+                expert_location_metadata is not None
+            ), "ExpertLocationMetadata is required for expert distribution recording. One possible"
+            "reason is that you are using a model that does not support expert distribution"
+            "recording. Try setting `get_model_config_for_expert_location` in your model."
             return _ExpertDistributionRecorderReal(
                 server_args, expert_location_metadata, rank
             )

python/sglang/srt/eplb/expert_location.py

@@ -82,6 +82,10 @@ def __post_init__(self):
     def init_trivial(server_args: ServerArgs, model_config: ModelConfig):
         """Trivial location - logical expert i corresponds to physical expert i"""
         common = ExpertLocationMetadata._init_common(server_args, model_config)
+
+        if common is None:
+            return None
+
         num_physical_experts = common["num_physical_experts"]
         model_config_for_expert_location = common["model_config_for_expert_location"]
         num_layers = model_config_for_expert_location.num_layers
@@ -109,6 +113,10 @@ def init_by_mapping(
         physical_to_logical_map = physical_to_logical_map.to(server_args.device)
 
         common = ExpertLocationMetadata._init_common(server_args, model_config)
+
+        if common is None:
+            return None
+
         model_config_for_expert_location = common["model_config_for_expert_location"]
         logical_to_all_physical_map = _compute_logical_to_all_physical_map(
             physical_to_logical_map,
@@ -133,6 +141,10 @@ def init_by_eplb(
         logical_count = logical_count.to(server_args.device)
 
         common = ExpertLocationMetadata._init_common(server_args, model_config)
+
+        if common is None:
+            return None
+
         model_config_for_expert_location = common["model_config_for_expert_location"]
         num_physical_experts = common["num_physical_experts"]
         num_groups = model_config_for_expert_location.num_groups
@@ -168,6 +180,9 @@ def _init_common(server_args: ServerArgs, model_config: ModelConfig):
             ModelConfigForExpertLocation.from_model_config(model_config)
         )
 
+        if model_config_for_expert_location is None:
+            return None
+
         num_physical_experts = (
             model_config_for_expert_location.num_logical_experts
             + server_args.ep_num_redundant_experts
@@ -398,10 +413,6 @@ class ModelConfigForExpertLocation:
     num_logical_experts: int
     num_groups: Optional[int] = None
 
-    @staticmethod
-    def init_dummy():
-        return ModelConfigForExpertLocation(num_layers=1, num_logical_experts=1)
-
     @staticmethod
     def from_model_config(model_config: ModelConfig):
         model_class, _ = get_model_architecture(model_config)
@@ -410,12 +421,12 @@ def from_model_config(model_config: ModelConfig):
                 model_config.hf_config
             )
         else:
-            return ModelConfigForExpertLocation.init_dummy()
+            return None
 
 
 def compute_initial_expert_location_metadata(
     server_args: ServerArgs, model_config: ModelConfig
-) -> ExpertLocationMetadata:
+) -> Optional[ExpertLocationMetadata]:
     data = server_args.init_expert_location
     if data == "trivial":
         return ExpertLocationMetadata.init_trivial(server_args, model_config)

python/sglang/srt/eplb/expert_location_dispatch.py

@@ -36,6 +36,7 @@ class ExpertLocationDispatchInfo:
     def init_new(cls, layer_id: int):
         ep_dispatch_algorithm = global_server_args_dict["ep_dispatch_algorithm"]
         expert_location_metadata = get_global_expert_location_metadata()
+        assert expert_location_metadata is not None
 
         if ep_dispatch_algorithm is None:
             return None

python/sglang/srt/eplb/expert_location_updater.py

@@ -50,6 +50,8 @@ def update(
             torch.cuda.empty_cache()
 
         old_expert_location_metadata = get_global_expert_location_metadata()
+        assert old_expert_location_metadata is not None
+
         _update_expert_weights(
             routed_experts_weights_of_layer=routed_experts_weights_of_layer,
             old_expert_location_metadata=old_expert_location_metadata,

python/sglang/srt/layers/moe/ep_moe/layer.py

@@ -183,6 +183,7 @@ def __init__(
         hidden_size: int,
         intermediate_size: int,
         layer_id: int,
+        num_fused_shared_experts: int = 0,
         params_dtype: Optional[torch.dtype] = None,
         quant_config: Optional[QuantizationConfig] = None,
         tp_size: Optional[int] = None,
@@ -196,6 +197,7 @@ def __init__(
             hidden_size=hidden_size,
             intermediate_size=intermediate_size,
             top_k=top_k,
+            num_fused_shared_experts=num_fused_shared_experts,
             layer_id=layer_id,
             params_dtype=params_dtype,
             quant_config=quant_config,
@@ -728,10 +730,19 @@ def weight_loader(
         shard_id: str,
         expert_id: int,
     ) -> None:
-        physical_expert_ids = (
-            get_global_expert_location_metadata().logical_to_all_physical(
-                self.layer_id, expert_id
+        global_expert_location_metadata = get_global_expert_location_metadata()
+        if global_expert_location_metadata is None:
+            self._weight_loader_impl(
+                param=param,
+                loaded_weight=loaded_weight,
+                weight_name=weight_name,
+                shard_id=shard_id,
+                expert_id=expert_id,
             )
+            return
+
+        physical_expert_ids = global_expert_location_metadata.logical_to_all_physical(
+            self.layer_id, expert_id
         )
         for physical_expert_id in physical_expert_ids:
             self._weight_loader_physical(
@@ -778,6 +789,7 @@ def __init__(
         hidden_size: int,
         intermediate_size: int,
         layer_id: int,
+        num_fused_shared_experts: int = 0,
         params_dtype: Optional[torch.dtype] = None,
         quant_config: Optional[QuantizationConfig] = None,
         tp_size: Optional[int] = None,
@@ -792,6 +804,7 @@ def __init__(
             hidden_size=hidden_size,
             intermediate_size=intermediate_size,
             layer_id=layer_id,
+            num_fused_shared_experts=num_fused_shared_experts,
             params_dtype=params_dtype,
             quant_config=quant_config,
             tp_size=tp_size,

python/sglang/srt/layers/moe/fused_moe_triton/layer.py

@@ -11,6 +11,7 @@
     get_tensor_model_parallel_world_size,
     tensor_model_parallel_all_reduce,
 )
+from sglang.srt.eplb.expert_location import get_global_expert_location_metadata
 from sglang.srt.layers.moe.topk import TopKOutput
 from sglang.srt.layers.quantization.base_config import (
     QuantizationConfig,
@@ -62,8 +63,9 @@ def __init__(
         num_experts: int,
         hidden_size: int,
         intermediate_size: int,
+        layer_id: int,
         top_k: Optional[int] = None,
-        layer_id: Optional[int] = None,
+        num_fused_shared_experts: int = 0,
         params_dtype: Optional[torch.dtype] = None,
         reduce_results: bool = False,
         quant_config: Optional[QuantizationConfig] = None,
@@ -84,13 +86,15 @@ def __init__(
         if params_dtype is None:
             params_dtype = torch.get_default_dtype()
 
+        self.layer_id = layer_id
         self.top_k = top_k
         self.hidden_size = hidden_size
         self.tp_size = (
             tp_size if tp_size is not None else get_tensor_model_parallel_world_size()
         )
         self.tp_rank = get_tensor_model_parallel_rank()
         self.num_experts = num_experts
+        self.num_fused_shared_experts = num_fused_shared_experts
         self.expert_map = None
 
         if enable_flashinfer_cutlass_moe and quant_config is None:
@@ -375,6 +379,45 @@ def weight_loader(
         shard_id: str,
         expert_id: int,
     ) -> None:
+
+        global_expert_location_metadata = get_global_expert_location_metadata()
+        if global_expert_location_metadata is None:
+            self._weight_loader_impl(
+                param=param,
+                loaded_weight=loaded_weight,
+                weight_name=weight_name,
+                shard_id=shard_id,
+                expert_id=expert_id,
+            )
+            return
+
+        if expert_id >= self.num_experts - self.num_fused_shared_experts:
+            # This is a shared expert.
+            physical_expert_ids = [expert_id]
+        else:
+            physical_expert_ids = (
+                global_expert_location_metadata.logical_to_all_physical(
+                    self.layer_id, expert_id
+                )
+            )
+
+        for physical_expert_id in physical_expert_ids:
+            self._weight_loader_physical(
+                param=param,
+                loaded_weight=loaded_weight,
+                weight_name=weight_name,
+                shard_id=shard_id,
+                expert_id=physical_expert_id,
+            )
+
+    def _weight_loader_physical(
+        self,
+        param: torch.nn.Parameter,
+        loaded_weight: torch.Tensor,
+        weight_name: str,
+        shard_id: str,
+        expert_id: int,
+    ) -> None:
         expert_id = self._map_global_expert_id_to_local_expert_id(expert_id)
         if expert_id == -1:
             return

python/sglang/srt/models/deepseek_v2.py

@@ -325,6 +325,7 @@ def __init__(
             num_experts=config.n_routed_experts
             + self.num_fused_shared_experts
             + global_server_args_dict["ep_num_redundant_experts"],
+            num_fused_shared_experts=self.num_fused_shared_experts,
             top_k=config.num_experts_per_tok + self.num_fused_shared_experts,
             hidden_size=config.hidden_size,
             intermediate_size=config.moe_intermediate_size,
@@ -2112,6 +2113,7 @@ def determine_num_fused_shared_experts(
 
         if disable_reason is not None:
             global_server_args_dict["disable_shared_experts_fusion"] = True
+            self.num_fused_shared_experts = 0
             log_info_on_rank0(
                 logger,
                 f"{disable_reason} Shared experts fusion optimization is disabled.",

python/sglang/srt/models/glm4_moe.py

@@ -434,6 +434,7 @@ def __init__(
             num_experts=config.n_routed_experts
             + self.num_fused_shared_experts
             + global_server_args_dict["ep_num_redundant_experts"],
+            num_fused_shared_experts=self.num_fused_shared_experts,
             top_k=config.num_experts_per_tok + self.num_fused_shared_experts,
             hidden_size=config.hidden_size,
             intermediate_size=config.moe_intermediate_size,
@@ -740,10 +741,11 @@ def determine_num_fused_shared_experts(
             global_server_args_dict["enable_deepep_moe"]
             or global_server_args_dict["enable_ep_moe"]
         ):
-            disable_reason = "Deepseek GLM-4.5 can not use shared experts fusion optimization when in deepep_moe or ep_moe mode."
+            disable_reason = "Deepseek and GLM-4.5 can not use shared experts fusion optimization when in deepep_moe or ep_moe mode."
 
         if disable_reason is not None:
             global_server_args_dict["disable_shared_experts_fusion"] = True
+            self.num_fused_shared_experts = 0
             log_info_on_rank0(
                 logger,
                 f"{disable_reason} Shared experts fusion optimization is disabled.",

python/sglang/srt/models/granitemoe.py

@@ -43,6 +43,7 @@ def __init__(
         top_k: int,
         hidden_size: int,
         intermediate_size: int,
+        layer_id: int,
         params_dtype: Optional[torch.dtype] = None,
         quant_config: Optional[QuantizationConfig] = None,
         tp_size: Optional[int] = None,
@@ -71,6 +72,7 @@ def __init__(
             top_k=top_k,
             hidden_size=hidden_size,
             intermediate_size=intermediate_size,
+            layer_id=layer_id,
             params_dtype=params_dtype,
             reduce_results=True,
             quant_config=quant_config,
@@ -203,6 +205,7 @@ def __init__(
             top_k=config.num_experts_per_tok,
             hidden_size=config.hidden_size,
             intermediate_size=config.intermediate_size,
+            layer_id=layer_id,
             quant_config=quant_config,
             prefix=f"{prefix}.block_sparse_moe",
         )

python/sglang/srt/models/grok.py

@@ -78,6 +78,7 @@ class Grok1MoE(nn.Module):
     def __init__(
         self,
         config: PretrainedConfig,
+        layer_id: int,
         num_experts: int,
         top_k: int,
         hidden_size: int,
@@ -128,6 +129,7 @@ def __init__(
         self.experts = MoEImpl(
             num_experts=num_experts,
             top_k=top_k,
+            layer_id=layer_id,
             hidden_size=hidden_size,
             intermediate_size=intermediate_size,
             params_dtype=params_dtype,
@@ -331,6 +333,7 @@ def __init__(
         )
         self.block_sparse_moe = Grok1MoE(
             config=config,
+            layer_id=layer_id,
             num_experts=config.num_local_experts,
             top_k=config.num_experts_per_tok,
             hidden_size=config.hidden_size,