[Refactor] Remove `VLLM_DEEPEP_LOW_LATENCY_ALLOW_NVLINK` (#27750)

Signed-off-by: yewentao256 <zhyanwentao@126.com>

vllm/distributed/device_communicators/all2all.py

@@ -363,7 +363,7 @@ class DeepEPLLAll2AllManager(DeepEPAll2AllManagerBase):
             num_rdma_bytes=num_rdma_bytes,
             low_latency_mode=True,
             num_qps_per_rank=num_qps_per_rank,
-            allow_nvlink_for_low_latency_mode=envs.VLLM_DEEPEP_LOW_LATENCY_ALLOW_NVLINK,
+            allow_nvlink_for_low_latency_mode=True,
             allow_mnnvl=envs.VLLM_DEEPEP_LOW_LATENCY_USE_MNNVL,
         )
 

vllm/envs.py

@@ -207,7 +207,6 @@ if TYPE_CHECKING:
     VLLM_OBJECT_STORAGE_SHM_BUFFER_NAME: str = "VLLM_OBJECT_STORAGE_SHM_BUFFER"
     VLLM_DEEPEP_BUFFER_SIZE_MB: int = 1024
     VLLM_DEEPEP_HIGH_THROUGHPUT_FORCE_INTRA_NODE: bool = False
-    VLLM_DEEPEP_LOW_LATENCY_ALLOW_NVLINK: bool = True
     VLLM_DEEPEP_LOW_LATENCY_USE_MNNVL: bool = False
     VLLM_DBO_COMM_SMS: int = 20
     VLLM_PATTERN_MATCH_DEBUG: str | None = None
@@ -1400,11 +1399,6 @@ environment_variables: dict[str, Callable[[], Any]] = {
     "VLLM_DEEPEP_HIGH_THROUGHPUT_FORCE_INTRA_NODE": lambda: bool(
         int(os.getenv("VLLM_DEEPEP_HIGH_THROUGHPUT_FORCE_INTRA_NODE", "0"))
     ),
-    # Allow DeepEP to use nvlink for internode_ll kernel, turn this on for
-    # better latency on GB200 like system
-    "VLLM_DEEPEP_LOW_LATENCY_ALLOW_NVLINK": lambda: bool(
-        int(os.getenv("VLLM_DEEPEP_LOW_LATENCY_ALLOW_NVLINK", "1"))
-    ),
     # Allow DeepEP to use MNNVL (multi-node nvlink) for internode_ll kernel,
     # turn this for better latency on GB200 like system
     "VLLM_DEEPEP_LOW_LATENCY_USE_MNNVL": lambda: bool(
@@ -1566,7 +1560,6 @@ def compute_hash() -> str:
         "VLLM_NVFP4_GEMM_BACKEND",
         "VLLM_USE_FBGEMM",
         "VLLM_DEEPEP_HIGH_THROUGHPUT_FORCE_INTRA_NODE",
-        "VLLM_DEEPEP_LOW_LATENCY_ALLOW_NVLINK",
         "VLLM_DEEPEP_LOW_LATENCY_USE_MNNVL",
     ]
     for key in environment_variables_to_hash: