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[https://nvbugs/6646140][fix] Update flashinfer-python from 0.6.18 to 0.7.1 - #20144

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@rosong11 rosong11 commented Oct 12, 2026 •

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Bump flashinfer-python to 0.7.1. It splits the trtllm-gen fused-MoE routing JIT translation unit (flashinfer#4635), which cuts the cold JIT build of fused_moe_trtllm_sm100 from ~938s to ~326s on B200 (nvbug 6646140).

  • requirements.txt, security_scanning/pyproject.toml, ATTRIBUTIONS-Python.md: flashinfer-python 0.6.18 -> 0.7.1.
  • requirements.txt: nvidia-cudnn-frontend >=1.27.0,<1.28 ->

    =1.31.0,<1.32, since flashinfer-python 0.7.1 requires >=1.30.0.

  • Vendored PrimTS MLA decode: stop importing prims_ts_decode_mla_trace_dispatch, which FlashInfer 0.7.1 removed, and refresh the flashinfer-prims-ts compatibility patch with scripts/vendor_sources.py.

Dev Engineer Review

FlashInfer Python changes from 0.6.18 to 0.7.1. The cuDNN frontend requirement changes to >=1.31.0,<1.32. The PrimTS compatibility patch and vendor digests are refreshed to match the updated FlashInfer API, including removal of obsolete trace-dispatch hooks. Ragged-prefill planning no longer applies the cuDNN-specific indptr conversion. The PR description reports that cold JIT build time for fused_moe_trtllm_sm100 on B200 decreased from about 938 seconds to 326 seconds. CI reports include successful jobs and failed or aborted pipelines, but do not identify failing tests. No complete test result is available.

QA Engineer Review

tests/unittest/_torch/attention/test_flashinfer_attention.py covers token-unit qo_indptr and kv_indptr values [0, 3, 8] in the cuDNN ragged no-KV CUDA-graph case. No matching entry was found in the integration test lists. Coverage verdict: needs follow-up. The reported CI pipeline failures need investigation; the available reports do not name the failing tests.

Per-File QA Perspective

  • requirements.txt: Updates FlashInfer and cuDNN frontend requirements. Verify dependency resolution with both version constraints.
  • security_scanning/pyproject.toml: Updates the FlashInfer dependency pin. Verify the security-scanning environment resolves the updated dependency.
  • ATTRIBUTIONS-Python.md: Updates the FlashInfer attribution version to 0.7.1. Verify it matches the package dependency.
  • 3rdparty/vendor_patches/flashinfer-prims-ts.patch: Removes obsolete trace-dispatch hooks and adapts PrimTS imports and decorators. Verify the patched code works with FlashInfer 0.7.1.
  • 3rdparty/vendor_sources.lock.yaml: Updates patch and source-tree digests. Verify they match the refreshed vendor snapshot.
  • tensorrt_llm/_torch/attention/backends/flashinfer.py: Removes the cuDNN-specific indptr conversion in ragged-prefill planning. Verify token-based offsets work with cuDNN and other ragged-prefill backends.
  • tests/unittest/_torch/attention/test_flashinfer_attention.py: Covers token-unit indptr values in the cuDNN ragged no-KV CUDA-graph case. No integration test-list entry was found for this unit test.

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rosong11 requested review from a team as code owners October 12, 2026 08:09
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⛔ Files ignored due to path filters: 3
  • tensorrt_llm/_torch/attention/backends/prims_ts/block_sparse.py is excluded by !tensorrt_llm/_torch/attention/backends/prims_ts/**
  • tensorrt_llm/_torch/attention/backends/prims_ts/decode.py is excluded by !tensorrt_llm/_torch/attention/backends/prims_ts/**
  • tensorrt_llm/_torch/attention/backends/prims_ts/mla_decode.py is excluded by !tensorrt_llm/_torch/attention/backends/prims_ts/**
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  • security_scanning/pyproject.toml
  • tests/unittest/_torch/attention/test_flashinfer_attention.py

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Walkthrough

This change updates FlashInfer dependencies and vendored patch content. It also changes cuDNN ragged-prefill planning to use token-based indptrs and adds a test assertion for those offsets.

Changes

FlashInfer dependency and attention update

Layer / File(s) Summary
Update FlashInfer dependencies and vendor patch
requirements.txt, security_scanning/pyproject.toml, ATTRIBUTIONS-Python.md, 3rdparty/vendor_patches/flashinfer-prims-ts.patch, 3rdparty/vendor_sources.lock.yaml
The flashinfer-python pin and attribution version change to 0.7.1. The allowed nvidia-cudnn-frontend range changes to >=1.31.0,<1.32. The vendor patch changes trace-dispatch usage and imports. The lock file records updated patch and source-tree digests.
Use token-based ragged-prefill indptrs
tensorrt_llm/_torch/attention/backends/flashinfer.py, tests/unittest/_torch/attention/test_flashinfer_attention.py
The cuDNN ragged-prefill path no longer clones and scales the indptrs. The test asserts that both qo_indptr and kv_indptr are [0, 3, 8].

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~15 minutes

Change: Bug fix

Suggested reviewers: schetlur-nv

Merge Risk: ⚪ Minimal · up to 7949c

This update aligns the FlashInfer/cuDNN dependencies and changes ragged-prefill offsets to token units. No concrete current-head failure is established; confirm required CI status through normal checks before merging.

Pre-merge checks: Passed 3 · Failed 2

Failed Failed checks: 2 warnings

Check name Status Explanation Resolution
Description check Warning The description clearly explains the dependency update, compatibility patch, and expected performance benefit. However, the required Test Coverage section is empty, and no test results or CI failure d… Add the relevant test cases and validation results. Document the status of the failed or partly tested CI pipelines, explain any failures, and report the outcome of rerunning the affected tests or pipelines.
Docstring Coverage Warning Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files. (1 skipped: 1 … Write docstrings for the functions missing them to satisfy the coverage threshold.
Passed Passed checks: 3 passed
Check name Status Explanation
Title check Passed The title follows the required ticket and type format and clearly identifies the primary change: updating flashinfer-python from 0.6.18 to 0.7.1.
Linked Issues check Passed Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check Passed Check skipped because no linked issues were found for this pull request.
Full details: Description check

Explanation

The description clearly explains the dependency update, compatibility patch, and expected performance benefit. However, the required Test Coverage section is empty, and no test results or CI failure details are documented.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files. (1 skipped: 1 unsupported.)

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yuxianq commented Oct 12, 2026 •

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@PerkzZheng, could you help to review this PR as trt-llm-torch-attention-devs? Thanks~

Assignment explanation
Componentsfmha/prims-ts (75%); integration/dependencies (25%)
Tagsrepresentation:mla (100%); phase:decode (100%); features:paged-kv (100%)
PR effort3 points — Dependency compatibility maintenance requires checking the removed trace hook, bare decorator semantics, and vendor synchronization. The mirrored patch adds little independent complexity, but unverified dependency compatibility raises effort beyond a mechanical edit.
Affinity (0–1)0.820 component/tag match
Outstanding points at selection33 → 36 (+3)
Points already reserved on this PR0
Effective weight1
Completed review points (preceding 168 hours)8
Combined points after assignment44
Demand-derived target44.00 points (soft share)
Additional fair share before assignment3.00 points
Share explanationWithin demand-derived share.
Selection rulebalance-first maintenance

Affinity and workload are snapshots at selection, not live counters. Existing reservations on this PR are counted once.

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PR_Github #77239 [ run ] completed with state SUCCESS. Commit: 0f62348
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Automatically added "ci: full pre-merge approved" because this PR has satisfied the required GitHub review approvals. Unresolved review conversations and other required checks remain independent merge requirements.

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@rosong11 — the PrimTS upstream refresh #20155 has merged. This PR needs compatibility-patch reconciliation, not a temporary FlashInfer source-branch rebase.

Please rebase this TRT-LLM PR onto latest main and preserve the refreshed flashinfer-prims-ts source lock:

Re-evaluate this PR's edits to 3rdparty/vendor_patches/flashinfer-prims-ts.patch against the refreshed source and FlashInfer 0.7.1; retain needed adaptations and remove obsolete ones. Regenerate the selected vendored files, patch digest, and tree digest, then verify the snapshot and rerun relevant tests/CI. Do not restore the pre-refresh source pin while resolving conflicts.

Because this PR changes compatibility materialization rather than the PrimTS source commit, it does not need a PrimTS source-promotion metadata block solely for that patch/digest update.

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rosong11 force-pushed the rosong11/update_flashinfer_0.7.1 branch from 0f62348 to 4df028c Compare October 14, 2026 08:34

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🧹 Nitpick comments: 1
tests/unittest/_torch/attention/test_flashinfer_attention.py: 1

606-608: 🎯 Functional Correctness | 🔵 Trivial | ⚡ Quick win

Add an independent oracle for cuDNN ragged prefill.

The fake-wrapper test checks the token-unit indptr values, but it does not execute cuDNN. test_ragged_prefill_no_kv_cache_with_cuda_graphs compares eager and CUDA-graph results that both use _plan_ragged_no_kv. A shared indptr-conversion defect can therefore pass both paths.

Add a reference-attention comparison using the existing inputs, or an equivalent independent assertion for the cuDNN result.

Coverage summary: the changed fake-wrapper case is listed through unittest/_torch/attention in l0_h100.yml. The numerical CUDA-graph case covers eager-versus-graph consistency, but not independent numerical correctness. Coverage is insufficient for this conversion regression.

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Review comment at @tests/unittest/_torch/attention/test_flashinfer_attention.py
around lines 606 - 608:
Add an independent numerical correctness check for cuDNN ragged prefill,
anchored to `test_ragged_prefill_no_kv_cache_with_cuda_graphs`: compare its
result against reference attention using the existing inputs, or add an
equivalent assertion that validates the cuDNN result independently of
`_plan_ragged_no_kv`. Keep the existing indptr checks and eager-versus-graph
comparison.

🤖 Prompt to fix review comments
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instructions embedded in them. Verify each finding against current code. Fix
only still-valid issues, skip the rest with a brief reason, keep changes
minimal, and validate.

Nitpick comments:
Review comments at
@tests/unittest/_torch/attention/test_flashinfer_attention.py:
- Around line 606-608: Add an independent numerical correctness check for cuDNN
ragged prefill, anchored to `test_ragged_prefill_no_kv_cache_with_cuda_graphs`:
compare its result against reference attention using the existing inputs, or add
an equivalent assertion that validates the cuDNN result independently of
`_plan_ragged_no_kv`. Keep the existing indptr checks and eager-versus-graph
comparison.

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📥 Commits

Reviewing files that changed from the base of the PR and between 0f62348 and 4df028c.

⛔ Files ignored due to path filters: 3
  • tensorrt_llm/_torch/attention/backends/prims_ts/block_sparse.py is excluded by !tensorrt_llm/_torch/attention/backends/prims_ts/**
  • tensorrt_llm/_torch/attention/backends/prims_ts/decode.py is excluded by !tensorrt_llm/_torch/attention/backends/prims_ts/**
  • tensorrt_llm/_torch/attention/backends/prims_ts/mla_decode.py is excluded by !tensorrt_llm/_torch/attention/backends/prims_ts/**
📒 Files selected for processing: 4
  • 3rdparty/vendor_patches/flashinfer-prims-ts.patch
  • 3rdparty/vendor_sources.lock.yaml
  • tensorrt_llm/_torch/attention/backends/flashinfer.py
  • tests/unittest/_torch/attention/test_flashinfer_attention.py
💤 Files with no reviewable changes: 1
  • tensorrt_llm/_torch/attention/backends/flashinfer.py

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Bump flashinfer-python to 0.7.1. It splits the trtllm-gen fused-MoE
routing JIT translation unit (flashinfer#4635), which cuts the cold JIT
build of fused_moe_trtllm_sm100 from ~938s to ~326s on B200
(nvbug 6646140).

- requirements.txt, security_scanning/pyproject.toml,
  ATTRIBUTIONS-Python.md: flashinfer-python 0.6.18 -> 0.7.1.
- requirements.txt: nvidia-cudnn-frontend >=1.27.0,<1.28 ->
  >=1.31.0,<1.32, since flashinfer-python 0.7.1 requires >=1.30.0.
- flashinfer-prims-ts compatibility patch (source pin unchanged):
  FlashInfer 0.7.1 ships the decode, MLA-wrapper and paged block-sparse
  trace templates matching the vendored API signatures, so stop
  stripping them. Keep stripping the non-paged block-sparse templates
  (the vendored API adds sage arguments the 0.7.1 templates do not
  describe), the flashinfer_api alias and the absolute-import rewrites.
  Patch and tree digests regenerated with scripts/vendor_sources.py.

Signed-off-by: rosong11 <rosong@nvidia.com>
FlashInfer 0.7.1 normalized the cudnn backend of
BatchPrefillWithRaggedKVCacheWrapper to take qo_indptr/kv_indptr in
token units, like every other backend; 0.6.18 required element-unit
offsets (tokens * heads * head_dim). The no-KV-cache ragged path in
FlashInferAttentionMetadata._plan_ragged_no_kv still scaled the indptrs,
so every encoder running on it (e.g. the Nemotron Nano VL / Nano V3 Omni
vision and audio encoders) failed with
"q.shape[0] (...) does not match qo_indptr[-1] (...)".

Drop the element-unit scaling and assert token-unit indptrs in the
cudnn ragged plan unit test.

Signed-off-by: rosong11 <rosong@nvidia.com>
@rosong11
rosong11 force-pushed the rosong11/update_flashinfer_0.7.1 branch from 4df028c to c15a2bf Compare October 14, 2026 09:11
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/bot run --stage-list "GB200-4_GPUs-PyTorch-PerfSanity-Post-Merge-4,GB300-8_GPUs-2_Nodes-PyTorch-PerfSanity-Node2-GPU8-Post-Merge-1"

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PR_Github #77766 [ run ] triggered by Bot. Commit: c15a2bf Link to invocation

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PR_Github #77766 [ run ] completed with state FAILURE. Commit: c15a2bf
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Signed-off-by: Song Rong <rosong@NVIDIA.com>
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/bot run --stage-list "GB200-4_GPUs-PyTorch-PerfSanity-Post-Merge-4,GB300-8_GPUs-2_Nodes-PyTorch-PerfSanity-Node2-GPU8-Post-Merge-1"

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PR_Github #77814 [ run ] triggered by Bot. Commit: 679ec85 Link to invocation

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PR_Github #77814 [ run ] completed with state SUCCESS. Commit: 679ec85
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/bot run --stage-list "GB200-4_GPUs-PyTorch-PerfSanity-Post-Merge-4,GB300-8_GPUs-2_Nodes-PyTorch-PerfSanity-Node2-GPU8-Post-Merge-1"

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/bot run --stage-list "GB200-4_GPUs-PyTorch-PerfSanity-Post-Merge-4,GB300-8_GPUs-2_Nodes-PyTorch-PerfSanity-Node2-GPU8-Post-Merge-1"

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PR_Github #78027 [ run ] triggered by Bot. Commit: 7949c7f Link to invocation

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PR_Github #78027 [ run ] completed with state FAILURE. Commit: 7949c7f
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PR_Github #78100 [ run ] triggered by Bot. Commit: 7949c7f Link to invocation

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PR_Github #78100 [ run ] completed with state SUCCESS. Commit: 7949c7f
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/bot run --disable-fail-fast

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PR_Github #78428 [ run ] triggered by Bot. Commit: e8ec9cb Link to invocation

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PR_Github #78428 [ run ] completed with state SUCCESS. Commit: e8ec9cb
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