[do not merge] fmhav2 hang

[jimmyzho]

📌 Description

🔍 Related Issues

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🧪 Tests

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Reviewer Notes

Summary by CodeRabbit

• Tests
  • Re-enabled previously skipped tests to improve coverage and validation of attention logic.
  • Adjusted a skip condition for certain numeric-format combinations so fewer cases are excluded, expanding tested dtype/output-dtype permutations.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request re-enables a test for the fmha_v2_prefill functionality that was previously marked to be skipped due to a known hanging issue. The change suggests that an underlying fix for the hang has been addressed, and this PR aims to allow the test to run and verify the resolution.

Highlights

• Test Re-enablement: The fmha_v2_prefill test, previously skipped due to a reported hang, has been re-enabled by uncommenting its pytestmark.skip decorator.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 1758226e-934c-4afd-8354-f3a8b8b1ac41

📥 Commits

Reviewing files that changed from the base of the PR and between f6835fd and 859505b.

📒 Files selected for processing (1)

• tests/attention/test_fmha_v2_prefill.py

🚧 Files skipped from review as they are similar to previous changes (1)

• tests/attention/test_fmha_v2_prefill.py

---

📝 Walkthrough

Walkthrough

Module-level pytestmark skip in tests/attention/test_fmha_v2_prefill.py was commented out so the file no longer is globally skipped. Inside test_trtllm_fmha_v2_prefill, the fp8 skip condition was broadened to skip whenever dtype == torch.float8_e4m3fn (independent of o_dtype).

Changes

Cohort / File(s)	Summary
Test file — skip marker & fp8 logic tests/attention/test_fmha_v2_prefill.py	Module-level pytestmark skip was commented out (file no longer globally skipped). In test_trtllm_fmha_v2_prefill, the fp8 skip condition changed from dtype == o_dtype == torch.float8_e4m3fn to dtype == torch.float8_e4m3fn (now ignores o_dtype).

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• tests: skip sliding window + fp8 to prevent hang in fmha_v2 unit tests #2781: Modifies the same test file and fp8-related skip logic; directly related.

Suggested reviewers

• bkryu
• nvmbreughe
• yzh119
• Anerudhan

Poem

🐰 I nudged a skip and set it free,
Tests hop out, come watch and see,
FP8 rules tightened, a tiny tweak,
CI hums softly, answers we seek. 🎈

🚥 Pre-merge checks | ❌ 3

❌ Failed checks (2 warnings, 1 inconclusive)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The PR description is entirely a blank template with no actual content filled in; all sections contain only placeholder text or unchecked boxes.	Complete the Description section explaining the hang issue and why the fp8 skip condition was modified, and fill in the Related Issues section with relevant issue links.
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Title check	❓ Inconclusive	The title is marked '[do not merge]' and vaguely references 'fmhav2 hang' without clearly summarizing the actual changes made to the codebase.	Replace with a descriptive title like 'Enable fmha_v2 prefill tests by refining fp8 skip condition' that accurately reflects the substantive changes without the '[do not merge]' marker.

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[gemini-code-assist]

Code Review

The pull request addresses a fmhav2 hang by re-enabling a previously skipped test. The change involves commenting out the pytest.mark.skip decorator. My feedback focuses on cleaning up the now-obsolete todo comment associated with the skipped test, ensuring clarity and consistency in the codebase.

[gemini-code-assist]

The pytest.mark.skip decorator was commented out, suggesting the fmhav2 hang is resolved and this test should now pass. If this is the case, the todo comment stating 'temporarily skip this test due to hangs' is obsolete and should be removed to prevent future confusion. Consider removing the entire commented block if the test is intended to run permanently.