Remove test skip logic for GEMM-AR tests

[vcherepanov-nv]

Description

cuBLASMp 0.6 and later uses NCCL fallback for GEMM+AR if NVL / multicast is not available.
This change removes test skip logic.

Fixes # (issue)

Type of change

• Documentation change (change only to the documentation, either a fix or a new content)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Infra/Build change
• Code refactoring

Changes

Please list the changes introduced in this PR:

• Don't skip tests, even if multicast is not supported

Checklist:

• I have read and followed the contributing guidelines
• The functionality is complete
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[greptile-apps]

Greptile Overview

Greptile Summary

Removes the multicast support check from GemmAr test fixture. cuBLASMp 0.6+ automatically falls back to NCCL when multicast/NVL hardware is unavailable, making the test skip logic unnecessary.

Key changes:

• Removed IsMulticastSupported() helper function
• Removed SetUp() override in GemmAr that skipped tests on devices without multicast support
• Tests will now run on all devices, relying on cuBLASMp's internal fallback mechanism

Confidence Score: 4/5

• This PR is safe to merge with low risk - it simplifies test logic by removing unnecessary skip conditions
• The change correctly removes test skip logic that is no longer needed with cuBLASMp 0.6+. However, there's a potential concern: the PR assumes all environments have cuBLASMp >= 0.6, but doesn't verify this at build/test time. If older cuBLASMp versions are still in use, tests could fail on hardware without multicast support
• No files require special attention - the change is straightforward

Important Files Changed

File Analysis

Filename	Score	Overview
tests/cpp_distributed/test_comm_gemm.cu	4/5	Removed multicast support check for GemmAr tests, allowing tests to run on all devices by relying on cuBLASMp 0.6+ NCCL fallback

Sequence Diagram

sequenceDiagram
    participant Test as GemmAr Test
    participant GemmAr as GemmAr Fixture
    participant NVTE as nvte_gemm_all_reduce
    participant cuBLASMp as cuBLASMp Library
    participant HW as Hardware/Device
    
    Note over Test,HW: Before this PR (cuBLASMp < 0.6)
    Test->>GemmAr: SetUp()
    GemmAr->>HW: Check multicast support
    alt Multicast not supported
        GemmAr->>Test: GTEST_SKIP()
        Note over Test: Test skipped
    else Multicast supported
        GemmAr->>Test: Continue
        Test->>NVTE: Run gemm_all_reduce
        NVTE->>cuBLASMp: Execute GEMM+AR with multicast
    end
    
    Note over Test,HW: After this PR (cuBLASMp >= 0.6)
    Test->>GemmAr: SetUp() [no override]
    GemmAr->>Test: Continue (no check)
    Test->>NVTE: Run gemm_all_reduce
    NVTE->>cuBLASMp: Execute GEMM+AR
    alt Hardware has multicast/NVL
        cuBLASMp->>HW: Use multicast
    else No multicast support
        cuBLASMp->>cuBLASMp: Fallback to NCCL
        cuBLASMp->>HW: Use NCCL allreduce
    end

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[greptile-apps]

Additional Comments (1)

1. tests/cpp_distributed/test_comm_gemm.cu, line 373 (link)

   style: if CUBLASMP_VERSION is not defined by the cuBLASMp headers, this will evaluate to #if 0 < 600 (true), causing the old behavior. Consider adding a check like:

   #if !defined(CUBLASMP_VERSION) || CUBLASMP_VERSION < 600

   to make the intent explicit and avoid silent failures if the macro isn't defined.

_{1 file reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

Additional Comments (1)

1. tests/cpp_distributed/test_comm_gemm.cu, line 336-366 (link)

   style: Consider verifying cuBLASMp >= 0.6 at build time. If older versions are still supported, tests will fail on hardware without multicast.

_{1 file reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

[timmoon10]

LGTM