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[https://nvbugs/6728119][fix] Keep NCCL off PCIe P2P in disagg tests on pre-Hopper nodes #19492

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Merged
chuangz0 merged 1 commit into from
Oct 15, 2026
Merged

[https://nvbugs/6728119][fix] Keep NCCL off PCIe P2P in disagg tests on pre-Hopper nodes #19492

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16 changes: 16 additions & 0 deletions tests/integration/defs/disaggregated/test_disaggregated.py
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Original file line number Diff line number Diff line change
Expand Up @@ -84,6 +84,21 @@ def get_ucx_tls():
return "^ib,gdr_copy"


def apply_pre_hopper_nccl_workaround(env: dict) -> None:
"""Keep NCCL off PCIe peer-to-peer on pre-Hopper CI nodes.

The 8xL40S CI nodes run with the AMD IOMMU in DMA translation mode, so
PCIe P2P writes across the host bridge fault (``AMD-Vi IO_PAGE_FAULT``)
and never land. NCCL still picks its P2P/CUMEM transport there, and the
first PP send/recv or TP collective in the warmup forward hangs the
worker before it can register with the disagg server
(https://nvbugs/6728119). Restricting P2P to PCIe-switch peers makes NCCL
fall back to SHM on those nodes; NVLink platforms are unaffected.
"""
if get_sm_version() < 90:
env.setdefault("NCCL_P2P_LEVEL", "PXB")


def cleanup_output_files():
"""Clean up output files from previous runs."""
for file in ['output.json', 'output_streaming.json']:
Expand Down Expand Up @@ -1059,6 +1074,7 @@ def run_disaggregated_test(example_dir,

run_env = env.copy() if env else os.environ.copy()
run_env["UCX_TLS"] = get_ucx_tls()
apply_pre_hopper_nccl_workaround(run_env)
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ctx_run_env = run_env.copy()
if ctx_env:
ctx_run_env.update(ctx_env)
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4 changes: 0 additions & 4 deletions tests/integration/test_lists/waives.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -156,11 +156,7 @@ full:H20/accuracy/test_llm_api_pytorch_multimodal.py::TestExaone4_5_33B::test_au
full:H20/accuracy/test_llm_api_pytorch_multimodal.py::TestExaone4_5_33B::test_auto_dtype[full_budget] SKIP (https://nvbugs/6597570)
full:H20/accuracy/test_llm_api_pytorch_multimodal.py::TestNanoV3Omni::test_auto_dtype[bf16] SKIP (https://nvbugs/6618649)
full:L40S/accuracy/test_llm_api_pytorch_encode.py::TestEncoderEncode::test_encoder_encode_cuda_graph_matches_eager_logits[bert-yelp] SKIP (https://nvbugs/6802114)
full:L40S/disaggregated/test_disaggregated.py::test_disaggregated_ctxpp2_genpp2 SKIP (https://nvbugs/6728119)
full:L40S/disaggregated/test_disaggregated.py::test_disaggregated_ctxpp2_gentp2 SKIP (https://nvbugs/6728119)
full:L40S/disaggregated/test_disaggregated.py::test_disaggregated_ctxtp2_genpp2 SKIP (https://nvbugs/6728119)
full:L40S/disaggregated/test_disaggregated.py::test_disaggregated_deepseek_v3_lite_fp8_attention_dp_overlap[DeepSeek-V3-Lite-fp8] SKIP (https://nvbugs/6581064)
full:L40S/disaggregated/test_disaggregated.py::test_disaggregated_multi_gpu SKIP (https://nvbugs/6728119)
full:RTXPro6000D/accuracy/test_llm_api_pytorch.py::TestQwen3_30B_A3B::test_nvfp4[dep4_latency_moe_cutlass-torch_compile=True] SKIP (https://nvbugs/5929339)
full:RTX_PRO_6000_Blackwell_Server_Edition/accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype[mtp_nextn=0-overlap_scheduler=False] SKIP (https://nvbugs/6616033)
full:RTX_PRO_6000_Blackwell_Server_Edition/accuracy/test_disaggregated_serving.py::TestDeepSeekV3Lite::test_auto_dtype[mtp_nextn=0-overlap_scheduler=True] SKIP (https://nvbugs/6616033)
Expand Down
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