[Refactor]Abstract Platform Interface for Distributed Backend and Add xccl Support for Intel XPU (vllm-project#19410)

dbyoung18 · jikunshang · Pradyun Ramadorai · commit 8b4bb229b140 · 2025-08-05T23:50:54.000-04:00
Signed-off-by: dbyoung18 &lt;yang5.yang@intel.com&gt;
Signed-off-by: Kunshang Ji &lt;kunshang.ji@intel.com&gt;
Co-authored-by: Kunshang Ji &lt;kunshang.ji@intel.com&gt;
diff --git a/docs/getting_started/installation/gpu/xpu.inc.md b/docs/getting_started/installation/gpu/xpu.inc.md
@@ -81,4 +81,9 @@ python -m vllm.entrypoints.openai.api_server \
 By default, a ray instance will be launched automatically if no existing one is detected in the system, with `num-gpus` equals to `parallel_config.world_size`. We recommend properly starting a ray cluster before execution, referring to the <gh-file:examples/online_serving/run_cluster.sh> helper script.
 
 # --8<-- [end:supported-features]
+# --8<-- [start:distributed-backend]
+
+XPU platform uses **torch-ccl** for torch<2.8 and **xccl** for torch>=2.8 as distributed backend, since torch 2.8 supports **xccl** as built-in backend for XPU.
+
+# --8<-- [end:distributed-backend]
 # --8<-- [end:extra-information]
diff --git a/vllm/platforms/__init__.py b/vllm/platforms/__init__.py
@@ -7,7 +7,7 @@
 from typing import TYPE_CHECKING, Optional
 
 from vllm.plugins import load_plugins_by_group
-from vllm.utils import resolve_obj_by_qualname
+from vllm.utils import resolve_obj_by_qualname, supports_xccl
 
 from .interface import _Backend  # noqa: F401
 from .interface import CpuArchEnum, Platform, PlatformEnum
@@ -139,10 +139,19 @@ def xpu_platform_plugin() -> Optional[str]:
     try:
         # installed IPEX if the machine has XPUs.
         import intel_extension_for_pytorch  # noqa: F401
-        import oneccl_bindings_for_pytorch  # noqa: F401
         import torch
+        if supports_xccl():
+            dist_backend = "xccl"
+        else:
+            dist_backend = "ccl"
+            import oneccl_bindings_for_pytorch  # noqa: F401
+
         if hasattr(torch, 'xpu') and torch.xpu.is_available():
             is_xpu = True
+            from vllm.platforms.xpu import XPUPlatform
+            XPUPlatform.dist_backend = dist_backend
+            logger.debug("Confirmed %s backend is available.",
+                         XPUPlatform.dist_backend)
             logger.debug("Confirmed XPU platform is available.")
     except Exception as e:
         logger.debug("XPU platform is not available because: %s", str(e))
diff --git a/vllm/platforms/cpu.py b/vllm/platforms/cpu.py
@@ -37,6 +37,7 @@ class CpuPlatform(Platform):
     device_name: str = "cpu"
     device_type: str = "cpu"
     dispatch_key: str = "CPU"
+    dist_backend: str = "gloo"
 
     @property
     def supported_dtypes(self) -> list[torch.dtype]:
diff --git a/vllm/platforms/cuda.py b/vllm/platforms/cuda.py
@@ -56,6 +56,7 @@ class CudaPlatformBase(Platform):
     device_type: str = "cuda"
     dispatch_key: str = "CUDA"
     ray_device_key: str = "GPU"
+    dist_backend: str = "nccl"
     device_control_env_var: str = "CUDA_VISIBLE_DEVICES"
 
     @property
diff --git a/vllm/platforms/hpu.py b/vllm/platforms/hpu.py
@@ -26,6 +26,7 @@ class HpuPlatform(Platform):
     device_type: str = "hpu"
     dispatch_key: str = "HPU"
     ray_device_key: str = "HPU"
+    dist_backend: str = "hccl"
     device_control_env_var: str = "HABANA_VISIBLE_MODULES"
 
     @classmethod
diff --git a/vllm/platforms/interface.py b/vllm/platforms/interface.py
@@ -129,6 +129,9 @@ class Platform:
     # compilation strategy.
     simple_compile_backend: str = "inductor"
 
+    # The backend used for distributed communication.
+    dist_backend: str = ""
+
     supported_quantization: list[str] = []
 
     additional_env_vars: list[str] = []
diff --git a/vllm/platforms/neuron.py b/vllm/platforms/neuron.py
@@ -30,6 +30,7 @@ class NeuronPlatform(Platform):
     device_type: str = "neuron"
     ray_device_key: str = "neuron_cores"
     supported_quantization: list[str] = ["neuron_quant", "fbgemm_fp8"]
+    dist_backend: str = "gloo"
     device_control_env_var: str = "NEURON_RT_VISIBLE_CORES"
 
     @classmethod
diff --git a/vllm/platforms/rocm.py b/vllm/platforms/rocm.py
@@ -164,6 +164,7 @@ class RocmPlatform(Platform):
     device_type: str = "cuda"
     dispatch_key: str = "CUDA"
     ray_device_key: str = "GPU"
+    dist_backend: str = "nccl"
     # rocm shares the same device control env var as CUDA
     device_control_env_var: str = "CUDA_VISIBLE_DEVICES"
 
diff --git a/vllm/platforms/tpu.py b/vllm/platforms/tpu.py
@@ -31,6 +31,7 @@ class TpuPlatform(Platform):
     device_type: str = "tpu"
     dispatch_key: str = "XLA"
     ray_device_key: str = "TPU"
+    dist_backend: str = "gloo"
     device_control_env_var: str = "TPU_VISIBLE_CHIPS"
     simple_compile_backend: str = "openxla"
 
diff --git a/vllm/platforms/xpu.py b/vllm/platforms/xpu.py
@@ -29,6 +29,7 @@ class XPUPlatform(Platform):
     # Intel XPU's device key is "GPU" for Ray.
     # see https://github.com/ray-project/ray/blob/6a5eb5865eeb9ccf058a79b44f107e327e360673/python/ray/_private/accelerators/intel_gpu.py#L20 # noqa: E501
     ray_device_key: str = "GPU"
+    dist_backend: str = "ccl"  # ccl | xccl
     device_control_env_var: str = "ONEAPI_DEVICE_SELECTOR"
 
     @classmethod
diff --git a/vllm/utils/__init__.py b/vllm/utils/__init__.py
@@ -1886,6 +1886,12 @@ def supports_dynamo() -> bool:
     return base_torch_version >= Version("2.4.0")
 
 
+# Supports xccl with PyTorch versions >= 2.8.0 for XPU platform
+def supports_xccl() -> bool:
+    return is_torch_equal_or_newer(
+        "2.8.0") and torch.distributed.is_xccl_available()
+
+
 # Some backends use pytorch version < 2.4.0 which doesn't
 # support `torch.library.custom_op`.
 def supports_custom_op() -> bool:
diff --git a/vllm/v1/worker/cpu_worker.py b/vllm/v1/worker/cpu_worker.py
@@ -11,6 +11,7 @@
 from vllm.distributed.parallel_state import get_pp_group, get_tp_group
 from vllm.logger import init_logger
 from vllm.model_executor.utils import set_random_seed
+from vllm.platforms import current_platform
 from vllm.sequence import IntermediateTensors
 from vllm.v1.core.sched.output import SchedulerOutput
 from vllm.v1.outputs import ModelRunnerOutput
@@ -58,7 +59,8 @@ def init_device(self):
         # Initialize the distributed environment.
         init_worker_distributed_environment(self.vllm_config, self.rank,
                                             self.distributed_init_method,
-                                            self.local_rank, "gloo")
+                                            self.local_rank,
+                                            current_platform.dist_backend)
         # Set random seed.
         set_random_seed(self.model_config.seed)
 
diff --git a/vllm/v1/worker/gpu_worker.py b/vllm/v1/worker/gpu_worker.py
@@ -157,7 +157,8 @@ def init_device(self):
         # Initialize the distributed environment.
         init_worker_distributed_environment(self.vllm_config, self.rank,
                                             self.distributed_init_method,
-                                            self.local_rank)
+                                            self.local_rank,
+                                            current_platform.dist_backend)
         # Set random seed.
         set_random_seed(self.model_config.seed)
 
diff --git a/vllm/v1/worker/tpu_worker.py b/vllm/v1/worker/tpu_worker.py
@@ -18,6 +18,7 @@
 from vllm.logger import init_logger
 from vllm.lora.request import LoRARequest
 from vllm.model_executor import set_random_seed
+from vllm.platforms import current_platform
 from vllm.utils import STR_DTYPE_TO_TORCH_DTYPE, cdiv
 from vllm.v1.attention.backends.pallas import TPU_HEAD_SIZE_ALIGNMENT
 from vllm.v1.core.sched.output import SchedulerOutput
@@ -300,7 +301,7 @@ def _init_tpu_worker_distributed_environment(
             rank=rank,
             local_rank=local_rank,
             distributed_init_method=distributed_init_method,
-            backend="gloo",
+            backend=current_platform.dist_backend,
         )
         ensure_model_parallel_initialized(
             parallel_config.tensor_parallel_size,
diff --git a/vllm/worker/hpu_worker.py b/vllm/worker/hpu_worker.py
@@ -23,6 +23,7 @@
 from vllm.lora.request import LoRARequest
 from vllm.model_executor import set_random_seed
 from vllm.model_executor.layers.sampler import SamplerOutput
+from vllm.platforms import current_platform
 from vllm.prompt_adapter.request import PromptAdapterRequest
 from vllm.sequence import ExecuteModelRequest
 from vllm.utils import bind_kv_cache
@@ -413,7 +414,7 @@ def init_worker_distributed_environment(
                                  rank,
                                  distributed_init_method,
                                  local_rank,
-                                 backend='hccl')
+                                 backend=current_platform.dist_backend)
 
     ensure_model_parallel_initialized(parallel_config.tensor_parallel_size,
                                       parallel_config.pipeline_parallel_size)
diff --git a/vllm/worker/neuron_worker.py b/vllm/worker/neuron_worker.py
@@ -156,7 +156,7 @@ def init_distributed_environment(self):
             rank=self.rank,
             local_rank=self.local_rank,
             distributed_init_method=self.distributed_init_method,
-            backend="gloo",
+            backend=current_platform.dist_backend,
         )
 
         ensure_model_parallel_initialized(
diff --git a/vllm/worker/worker.py b/vllm/worker/worker.py
@@ -530,7 +530,8 @@ def init_worker_distributed_environment(
     set_custom_all_reduce(not parallel_config.disable_custom_all_reduce)
 
     init_distributed_environment(parallel_config.world_size, rank,
-                                 distributed_init_method, local_rank)
+                                 distributed_init_method, local_rank,
+                                 current_platform.dist_backend)
     ensure_model_parallel_initialized(parallel_config.tensor_parallel_size,
                                       parallel_config.pipeline_parallel_size)
 
