From 4b45d556a7e66d1d978e6df14098a8ba87606a4b Mon Sep 17 00:00:00 2001
From: Qiaolin Yu <liin1211@outlook.com>
Date: Mon, 24 Nov 2025 18:15:24 -0800
Subject: [PATCH] Overlap glm moe gemms in two cuda streams (#13786)

---
 python/sglang/srt/models/glm4_moe.py | 50 ++++++++++++++++++++++++++--
 1 file changed, 47 insertions(+), 3 deletions(-)

diff --git a/python/sglang/srt/models/glm4_moe.py b/python/sglang/srt/models/glm4_moe.py
index 3b04422b1..0267a9593 100644
--- a/python/sglang/srt/models/glm4_moe.py
+++ b/python/sglang/srt/models/glm4_moe.py
@@ -448,12 +448,56 @@ class Glm4MoeSparseMoeBlock(nn.Module):
     ) -> torch.Tensor:
 
         if not get_moe_a2a_backend().is_deepep():
-            return self.forward_normal(
-                hidden_states, should_allreduce_fusion, use_reduce_scatter
-            )
+            if (
+                self.alt_stream is not None
+                and hidden_states.shape[0] > 0
+                and get_is_capture_mode()
+            ):
+                return self.forward_normal_dual_stream(
+                    hidden_states, should_allreduce_fusion, use_reduce_scatter
+                )
+            else:
+                return self.forward_normal(
+                    hidden_states, should_allreduce_fusion, use_reduce_scatter
+                )
         else:
             return self.forward_deepep(hidden_states, forward_batch)
 
+    def forward_normal_dual_stream(
+        self,
+        hidden_states: torch.Tensor,
+        should_allreduce_fusion: bool = False,
+        use_reduce_scatter: bool = False,
+    ) -> torch.Tensor:
+        current_stream = torch.cuda.current_stream()
+        self.alt_stream.wait_stream(current_stream)
+        shared_output = self._forward_shared_experts(hidden_states)
+        with torch.cuda.stream(self.alt_stream):
+            # router_logits: (num_tokens, n_experts)
+            router_logits = self.gate(hidden_states)
+            topk_output = self.topk(hidden_states, router_logits)
+
+            final_hidden_states = self.experts(hidden_states, topk_output)
+            if not _is_cuda and not _use_aiter:
+                # fused in biased_grouped_topk so we can skip here
+                final_hidden_states *= self.routed_scaling_factor
+
+        current_stream.wait_stream(self.alt_stream)
+        with use_symmetric_memory(
+            parallel_state.get_tp_group(), disabled=not is_allocation_symmetric()
+        ):
+            final_hidden_states_out = torch.empty_like(final_hidden_states)
+        torch.add(final_hidden_states, shared_output, out=final_hidden_states_out)
+        final_hidden_states = final_hidden_states_out
+        if (
+            self.tp_size > 1
+            and not should_allreduce_fusion
+            and not use_reduce_scatter
+            and not should_use_flashinfer_cutlass_moe_fp4_allgather()
+        ):
+            final_hidden_states = tensor_model_parallel_all_reduce(final_hidden_states)
+        return final_hidden_states
+
     def forward_normal(
         self,
         hidden_states: torch.Tensor,