[Wanli-Jiang]

Dev Engineer Review

• Updated the default all-reduce tactic policy for SM103.
• SM103 now selects NCCL instead of NCCL symmetric when no cached tactic exists.
• Added capability checks for NCCL symmetric auto tactics and symmetric-memory windows.
• Preserved explicit NCCL symmetric selection and fallback behavior when device discovery is unavailable.
• Added compile-time assertions for the SM103 and non-SM103 policies.
• No public API or exported declaration changes were identified.
• The changes are consistent across the C++ and Python implementations.

QA Engineer Review

• Added test functions:
  • test_sm103_excludes_nccl_symmetric_from_auto
  • test_other_capability_preserves_nccl_symmetric_auto
  • test_unavailable_capability_preserves_existing_policy
  • test_sm103_auto_tactics_and_cache_miss_use_safe_collectives
  • test_non_sm103_auto_preserves_symmetric_tactic_and_fallback
  • test_sm103_auto_does_not_request_nccl_window_output
  • test_non_sm103_auto_preserves_nccl_window_output
• These tests cover SM103 behavior, non-SM103 behavior, unavailable device discovery, tactic filtering, cache-miss fallback, and symmetric-memory-window selection.
• No tests/integration/test_lists/ coverage entry was provided for these unit tests.
• Verdict: needs follow-up.

Description

Test Coverage

PR Checklist

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• PR Follows TRT-LLM CODING GUIDELINES to the best of your knowledge.

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• Please check this after reviewing the above items as appropriate for this PR.

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[Wanli-Jiang]

verified not necessary, close the PR.

[coderabbitai]

Caution

Review failed

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: 8de9954d-3a43-4317-83a2-5e9f22722c3a

📥 Commits

Reviewing files that changed from the base of the PR and between f04859d and 82bc0ce.

📒 Files selected for processing (4)

• cpp/tensorrt_llm/thop/allreduceOp.cpp
• tensorrt_llm/_torch/custom_ops/torch_custom_ops.py
• tensorrt_llm/_torch/distributed/ops.py
• tests/unittest/_torch/distributed/test_allreduce_auto_policy.py

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Walkthrough

AllReduce AUTO tactic selection now checks NCCL symmetric support. SM103 uses NCCL instead of NCCL symmetric, including cache-miss fallbacks and memory-window selection. Other architectures preserve the existing symmetric behavior.

Changes

AllReduce policy

Layer / File(s)	Summary
Capability and window policy tensorrt_llm/_torch/distributed/ops.py, tests/unittest/_torch/distributed/test_allreduce_auto_policy.py	AUTO NCCL symmetric support is disabled on SM103. Explicit NCCL strategies remain eligible. Tests cover supported, unsupported, and unavailable device capability cases.
Python tactic selection and fallback tensorrt_llm/_torch/custom_ops/torch_custom_ops.py, tests/unittest/_torch/distributed/test_allreduce_auto_policy.py	The runner filters unsupported NCCL symmetric tactics and selects NCCL or NCCL symmetric for cache misses according to platform support.
C++ cache-miss fallback cpp/tensorrt_llm/thop/allreduceOp.cpp	The uncached autotuned path selects NCCL on SM103 and NCCL symmetric on other architectures.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Suggested reviewers: bowenfu

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests

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