[TRTLLM-9467][fix] Fix PP+CP combination with helix parallelism

Signed-off-by: Balaram Buddharaju <[email protected]>

Author: brb-nv

tensorrt_llm/_torch/distributed/communicator.py

@@ -407,6 +407,10 @@ def create_cp_comm(self):
     def cp_allgather(self, obj):
         return self.cp_comm.allgather(obj)
 
+    def cp_broadcast(self, obj, root=0, chunk_size: int = 4 * 1024 * 1024):
+        comm = self.cp_comm
+        return safe_broadcast(comm, obj, root=root, chunk_size=chunk_size)
+
     def tp_allgather(self, obj):
         return self.tp_comm.allgather(obj)
 
@@ -723,6 +727,20 @@ def tp_broadcast(self, obj, root=0):
                 device=torch.device("cpu"))
             return ret[0]
 
+    @log_op
+    def cp_broadcast(self, obj, root=0):
+        if isinstance(obj, torch.Tensor):
+            dist.broadcast(obj, src=root, group=self.mapping.cp_group_pg)
+            return obj
+        else:
+            ret = [obj]
+            torch.distributed.broadcast_object_list(
+                ret,
+                src=root,
+                group=self.mapping.cp_group_pg,
+                device=torch.device("cpu"))
+            return ret[0]
+
     @log_op
     def pp_allgather(self, obj):
         if isinstance(obj, torch.Tensor):

tensorrt_llm/_torch/pyexecutor/executor_request_queue.py

@@ -587,9 +587,15 @@ def _broadcast_new_requests(
         if not self.dist.has_pp:
             return self.dist.broadcast(payloads, root=0)
 
-        # Broadcast within first tp group before send/recv chain to other tp groups
-        if self.dist.tp_size > 1 and self.dist.is_first_pp_rank:
-            payloads = self.dist.tp_broadcast(payloads, root=0)
+        # Broadcast within first PP stage before send/recv chain to other PP stages.
+        # This needs to cover both TP and CP ranks within the first PP stage.
+        if self.dist.is_first_pp_rank:
+            if self.dist.tp_size > 1:
+                payloads = self.dist.tp_broadcast(payloads, root=0)
+            # Also broadcast within CP group when CP is enabled (helix parallelism).
+            # This ensures all CP ranks within the first PP stage receive the requests.
+            if self.dist.cp_size > 1:
+                payloads = self.dist.cp_broadcast(payloads, root=0)
 
         # Tag for communication
         tag = self.dist.pp_size  # Use pp_size as tag to avoid conflicts

tests/integration/defs/accuracy/test_disaggregated_serving.py

@@ -871,7 +871,9 @@ def test_auto_dtype(self, overlap_scheduler, mtp_nextn):
             task = GSM8K(self.MODEL_NAME)
             task.evaluate(llm)
 
-    @pytest.mark.skip_less_device(4)
+    @pytest.mark.skip_less_device(8)
+    @pytest.mark.parametrize("gen_pp,gen_tp,gen_cp", [(1, 2, 2), (2, 1, 2)],
+                             ids=["pp1tp2cp2", "pp2tp1cp2"])
     @pytest.mark.parametrize("cuda_graph_config", [
         None,
         {
@@ -888,8 +890,10 @@ def test_auto_dtype(self, overlap_scheduler, mtp_nextn):
                                  "cudagraph:with_padding"
                              ])
     @pytest.mark.parametrize("comms_medium", ["fifo", "nccl"])
-    def test_auto_dtype_with_helix(self, comms_medium, cuda_graph_config):
+    def test_auto_dtype_with_helix(self, comms_medium, cuda_graph_config,
+                                   gen_pp, gen_tp, gen_cp):
         use_nccl_for_alltoall = comms_medium == "nccl"
+        gen_ep = gen_tp * gen_cp
         kv_cache_config = {
             "free_gpu_memory_fraction": 0.5,
             "enable_block_reuse": False,
@@ -898,20 +902,22 @@ def test_auto_dtype_with_helix(self, comms_medium, cuda_graph_config):
         }
         ctx_server_config = {
             "pipeline_parallel_size": 1,
-            "tensor_parallel_size": 2,
+            "tensor_parallel_size": 4,
             "context_parallel_size": 1,
             "disable_overlap_scheduler": True,
             "kv_cache_config": kv_cache_config,
             "enable_chunked_prefill": False,
             "cuda_graph_config": None,
             "cache_transceiver_config": {
-                "backend": "UCX"
+                "backend": "UCX",
+                "max_tokens_in_buffer": 8192,
             },
         }
         gen_server_config = {
-            "tensor_parallel_size": 1,
-            "pipeline_parallel_size": 1,
-            "context_parallel_size": 2,
+            "tensor_parallel_size": gen_tp,
+            "pipeline_parallel_size": gen_pp,
+            "context_parallel_size": gen_cp,
+            "moe_expert_parallel_size": gen_ep,
             "cp_config": {
                 "cp_type": "HELIX",
                 "tokens_per_block": 32,
@@ -922,7 +928,8 @@ def test_auto_dtype_with_helix(self, comms_medium, cuda_graph_config):
             "enable_chunked_prefill": False,
             "cuda_graph_config": cuda_graph_config,
             "cache_transceiver_config": {
-                "backend": "UCX"
+                "backend": "UCX",
+                "max_tokens_in_buffer": 8192,
             },
         }
         disaggregated_server_config = {

tests/integration/test_lists/qa/llm_function_core.txt

@@ -540,14 +540,14 @@ accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_guided_decoding
 accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_guided_decoding[xgrammar-mtp_nextn=2]
 accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_guided_decoding[llguidance-mtp_nextn=0]
 accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_guided_decoding[llguidance-mtp_nextn=2]
-accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[nccl-cudagraph:none]
-accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[nccl-cudagraph:without_padding]
-accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[nccl-cudagraph:with_padding]
-accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[fifo-cudagraph:none]
-accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[fifo-cudagraph:without_padding]
-accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[fifo-cudagraph:with_padding]
 accuracy/test_disaggregated_serving.py::TestGemma3_1BInstruct::test_auto_dtype[False]
 accuracy/test_disaggregated_serving.py::TestGemma3_1BInstruct::test_auto_dtype[True]
+accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[nccl-cudagraph:none-pp2tp1cp2]
+accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[nccl-cudagraph:without_padding-pp2tp1cp2]
+accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[nccl-cudagraph:with_padding-pp2tp1cp2]
+accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[fifo-cudagraph:none-pp2tp1cp2]
+accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[fifo-cudagraph:without_padding-pp2tp1cp2]
+accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[fifo-cudagraph:with_padding-pp2tp1cp2]
 accuracy/test_disaggregated_serving.py::TestGPTOSS::test_auto_dtype[True]
 accuracy/test_disaggregated_serving.py::TestGPTOSS::test_auto_dtype[False]
 accuracy/test_llm_api_pytorch.py::TestQwen3_8B::test_w4a8_mxfp4[fp8-latency]

tests/integration/test_lists/test-db/l0_dgx_b200.yml

@@ -66,6 +66,7 @@ l0_dgx_b200:
       backend: pytorch
       orchestrator: mpi
   tests:
+  - accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[fifo-cudagraph:with_padding-pp2tp1cp2] TIMEOUT (60)
   - accuracy/test_llm_api_pytorch.py::TestDeepSeekR1::test_nvfp4_multi_gpus[throughput] TIMEOUT (60)
   - accuracy/test_llm_api_pytorch.py::TestDeepSeekR1::test_nvfp4_multi_gpus[throughput_mtp] TIMEOUT (60)
   - accuracy/test_llm_api_pytorch.py::TestDeepSeekR1::test_nvfp4_multi_gpus[throughput_bs8_mtp] TIMEOUT (60)
@@ -92,6 +93,7 @@ l0_dgx_b200:
       backend: pytorch
       orchestrator: mpi
   tests:
+  - accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[nccl-cudagraph:with_padding-pp2tp1cp2] TIMEOUT (60)
   - accuracy/test_llm_api_pytorch.py::TestDeepSeekR1::test_nvfp4_multi_gpus_corner_case TIMEOUT (60)
   - accuracy/test_llm_api_pytorch.py::TestDeepSeekV32::test_fp8_blockscale[baseline_fp8kv] TIMEOUT (60)
   - accuracy/test_llm_api_pytorch.py::TestDeepSeekV32::test_fp8_blockscale[latency] TIMEOUT (60)

tests/integration/test_lists/test-db/l0_gb200_multi_gpus.yml

@@ -72,8 +72,6 @@ l0_gb200_multi_gpus:
   - accuracy/test_llm_api_pytorch.py::TestQwen3NextInstruct::test_nvfp4[tp4ep4-cutlass]
   - accuracy/test_llm_api_pytorch.py::TestQwen3NextInstruct::test_nvfp4[no_cuda_graph_overlap-cutlass]
   - accuracy/test_llm_api_pytorch.py::TestQwen3NextInstruct::test_nvfp4[tp4ep4-trtllm]
-  - accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[nccl-cudagraph:none]
-  - accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[fifo-cudagraph:none]
   - accuracy/test_llm_api_pytorch.py::TestMistralLarge3_675B::test_nvfp4_4gpus[latency_moe_trtllm_eagle] TIMEOUT (90)
 - condition:
     ranges:
@@ -89,10 +87,6 @@ l0_gb200_multi_gpus:
       stage: post_merge
       backend: pytorch
   tests:
-  - accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[nccl-cudagraph:without_padding]
-  - accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[nccl-cudagraph:with_padding]
-  - accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[fifo-cudagraph:without_padding]
-  - accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype_with_helix[fifo-cudagraph:with_padding]
   - accuracy/test_llm_api_pytorch.py::TestLlama3_1_8BInstruct::test_fp8_4gpus[tp4-fp8kv=True-attn_backend=FLASHINFER-torch_compile=True]
   - accuracy/test_llm_api_pytorch.py::TestLlama3_1_8BInstruct::test_fp8_4gpus[pp4-fp8kv=False-attn_backend=TRTLLM-torch_compile=False]
   - accuracy/test_llm_api_pytorch.py::TestDeepSeekV3Lite::test_nvfp4_4gpus[moe_backend=CUTLASS-mtp_nextn=0-ep4-fp8kv=True-attention_dp=True-cuda_graph=True-overlap_scheduler=True-torch_compile=False]