feat: mtp support dp-attention (#6081)

Co-authored-by: austindeng <austindeng@tencent.com>
Co-authored-by: tianqilin.99 <tianqilin.99@bytedance.com>
Co-authored-by: Qiaolin Yu <liin1211@outlook.com>
Co-authored-by: ch-wan <cwan39@gatech.edu>

python/sglang/srt/models/deepseek_v2.py

@@ -1399,7 +1399,9 @@ class DeepseekV2DecoderLayer(nn.Module):
         rope_scaling = getattr(config, "rope_scaling", None)
         max_position_embeddings = getattr(config, "max_position_embeddings", 8192)
         self.enable_dp_attention = global_server_args_dict["enable_dp_attention"]
+        self.speculative_algorithm = global_server_args_dict["speculative_algorithm"]
         self.layer_id = layer_id
+        self.is_nextn = is_nextn
         self.self_attn = DeepseekV2AttentionMLA(
             config=config,
             hidden_size=self.hidden_size,
@@ -1500,6 +1502,11 @@ class DeepseekV2DecoderLayer(nn.Module):
             hidden_states, residual, forward_batch
         )
 
+        if self.enable_dp_attention and self.speculative_algorithm.is_eagle():
+            # NOTE: this line resolves the degradation of MTP reception rate for non-zero DP ranks.
+            # See discussion here (https://github.com/sgl-project/sglang/pull/6081#discussion_r2147452251).
+            hidden_states = hidden_states.clone()
+
         return hidden_states, residual
 
     def op_comm_prepare_attn(