[MiniMax-M3] Restrict Triton FP8 indexer admission to supported CUDA devices

[venkywonka]

Purpose

MiniMax-M3 requests with indexer_kv_dtype=fp8 currently fail on SM120 because the Triton indexer admits only BF16. Permit E4M3 index caches on CUDA devices reporting FP8 support, while preserving BF16 fallback, SM100-family/top-k16 MSA dispatch, and rejection of unsupported dtypes and platforms.

This is a hardening and current-main integration follow-up based on #47665 (head 7c6cd929c257b7c5df904bb5e563cfc2ff6e9d82, still open). Jarrel Seah's PR owns the E4M3 enablement and both scorer casts, which are reused here. The independently useful changes are:

• Restrict its dtype-only Triton allowlist with is_cuda() and supports_fp8(). This preserves rejection on older CUDA devices and separate platform backends, including ROCm.
• Add a 126-case admission matrix and enroll it in the existing CPU model CI job.
• Extend the existing kernel reference test to cover production FP8 queries and keys, mixed BF16/FP8 inputs, prefill/decode, and one/four query tokens. The owner's tests keep queries BF16; the model emits FP8 queries when its index cache is FP8.

This draft overlaps #47665's prerequisite hunks so it builds directly against main; those hunks are credited rather than presented as new enablement. Related ROCm #53448 and AITER #52664 do not supply these CUDA admission boundaries. Coordination with the existing owner is needed before choosing how to land the shared changes.

Rebased without conflicts onto 8c87c333b84c85908b1d11f0044457692277c6f3. No grid, top-k buffer layout, or public dtype-option changes. AI assistance was used: Codex, gpt-6-astra, xhigh. This is a draft for human review; human line-by-line review and GPU/model qualification are not claimed complete.

Test Plan

Executed on ComputeLab Austin RTX PRO 6000 Blackwell Server Edition (SM120), source e2b15a1341df1bca125ee42bb15fb1dc659937d8:

.venv/bin/python -m pytest tests/models/test_minimax_m3_indexer.py -q
.venv/bin/python -m pytest tests/kernels/attention/test_minimax_m3.py \
  -k 'test_index_topk_fp8 or test_decode_index_topk_correctness' -q
.venv/bin/python -m pytest tests/kernels/test_fused_minimax_m3_qknorm_rope_kv_insert.py \
  -k sparse_full_fp8_index -q
.venv/bin/python -m pytest tests/kernels/test_minimax_m3_sparse_attn_fp8_scale.py -q

A separate local validation harness exercised 72 core and 36 long-context cases with FP64 references formed from the stored values, fixed atol=1e-5 / rtol=1.3e-6, exact unordered top-k selection, forced blocks, zero-length padding and three graph replays. Long cases include 384Ki, 751Ki, 769Ki and 1Mi key lengths. The harness and raw receipts are retained as validation artifacts rather than added as a second upstream test suite.

Pending: canonical real-sampler TP4/TP8 MiniMax-M3 NVFP4 GSM8K and long-context serving. Serialized BF16/FP8 cache/scan measurements are complete below. The shared TP8 BF16 baseline may be reused only with matching source/model/runtime/config/prompt/sampler fingerprints. Pilot32 is for timing estimates only; full GSM8K remains 1,319 questions.

Test Result

Austin correctness completed on 2026-09-10 UTC, without source fixes or oracle changes:

Check	Result
Admission boundaries (CPU logic on the assigned Austin step)	126 passed
Native GPU indexer/padded-decode tests	22 passed
Native fused FP8 query/key producer	8 passed
Native sparse-attention FP8 scale tests	4 passed
Supplemental core cases	72 passed
Supplemental long-context cases, up to 1,048,576 keys	36 passed

The four pytest suites and both supplemental suites reported 0 failed, 0 errors and 0 skipped. All supplemental graph replays reproduced their outputs bitwise; there were no top-k mismatches. These references check computation from the quantized stored values, not equivalence to unquantized model outputs. Model accuracy is still pending.

The assigned GPU was verified as compute capability12.0 inside the actual container, with a CUDA health check and exact source/native import checks. Runtime: torch 2.13.0+cu130, Triton 3.7.1, FlashInfer 0.6.18.post1, CUDA13.0. The private exact-head wheel was verified against all2,391 tracked Python files and all17 native libraries against the now-available official base8c87 wheel; native source/build inputs are unchanged. No historical image-native vLLM/Torch was used.

Changed-file pre-commit hooks and post-rebase admission checks also passed before publication. Earlier offline compilation covered96 supported specializations and rejected all8 SM80 E4M3 negative cases; those compiler checks are separate from the actual Austin results above.

Austin paired kernel measurements also completed at the same exact head in step 23512.60 (COMPLETED0:0, 5m41s including inventory/preflight/teardown): 72/72 rows passed, 0 failed/skipped, 0 top-k mismatches, 14,400 retained CUPTI samples. The 12 shapes cover 8Ki/128Ki/1Mi keys, batch1/8 and query length1/4 with one local index head. BF16/BF16, BF16/E4M3 and E4M3/E4M3 run in balanced A/B/C/C/B/A order, with stored-value FP64 correctness checked before timing. FlashInfer CUPTI13.0.1 uses CUDA graphs, cold L2, 25 explicit warmup calls plus 25 helper dry-run iterations, and 100 samples per trial/boundary. Input/reference/allocation/CPU-wrapper work is outside GPU kernel timing.

The table divides pooled BF16/BF16 latency by pooled configuration latency across both trial directions. These are dtype comparisons within one source head, not before/after PR or serving gains.

Query / cache dtype	Scan-only ratio range	Scan + top-k ratio range	Faster shapes per boundary
BF16 / E4M3	1.210–1.891×	1.095–1.857×	12/12
E4M3 / E4M3	1.387–1.906×	1.166–1.870×	12/12

FP8 index-cache allocation was exactly half of BF16 for every shape. At 1Mi keys, batch8 and query length4, BF16/BF16 versus E4M3/E4M3 used 2GiB versus 1GiB of index cache; scan latency was 1478.745 versus 777.573µs, and scan+top-k was 1598.954 versus 895.621µs. Both trial directions agree; maximum forward/reverse median drift was 5.62%. All 77 closed artifact hashes matched. Independent Astra xhigh review recomputed all sample medians, ratios, byte accounting and CSV/plot outputs. Raw results SHA256: 26301996afce55ee8836457343624bda95354988b0334ce2b7747b5690580f00; preflight SHA256: 4605604e53a6e5de7fb030cbde66928c20e5770e2aa763a85656dca6c7921dbf. No source or numerical-harness fix was needed.

Private validation-helper regressions were also corrected and reviewed: 163 CPU checks passed: 21 launch, 63 canonical-runner, 17 paired-result-reader and 62 origin/cleanup checks. The fixes cover Austin shell guards, ordered GPU grants, cancellation during startup/long requests, and the pinned evaluator's serialized chat-prompt format. The reader checks full question/filter coverage and reports paired losses even when aggregate scores match. Pre-fix helper failures are preserved separately from native results; these CPU checks do not qualify model execution.

One subsequent private-helper preparation turn ran on gpt-5.6-luna / low, violating the requested model constraint; its earlier Astra attribution was corrected. All intervening helper changes were independently audited and re-tested on gpt-6-astra / xhigh before model execution. No GPU ran during that incident. The repaired controls validate top-level and active package versions and capture loopback JSON server configuration under the separately sealed execution supplement, without changing the immutable baseline inputs.

GitHub's pre-run-check is blocked by its contributor-trust/label policy (zero merged PRs found for the author and no qualifying label), so upstream pre-commit did not execute. The failed check is not a source/test failure; local changed-file hooks and the Austin checks above passed. No readiness label was added.

The shared BF16 baseline's previous configuration failed after weight loading, before health/pilot, with No common block size for16 (zero evaluated questions). Its failed attempt and original inputs are retained. Future model arms use immutable config 8860a5499872 with explicit block_size=128 and speculative_config.attention_backend=TRITON_ATTN, plus matching introspection supplement 00ac787dae89. The private controls require resolved cache block size128 and the fully qualified Triton draft backend before evaluation; this is a configuration correction, with no production-source change.

The shared exact-base TP8 BF16 evaluator subsequently completed all 1,319 questions with exit 0, scoring 1,269/1,319 (96.209%) on both filters. Its enclosing step failed during JSONL postprocessing: four literal U+2028 characters inside answers were incorrectly treated as record separators. The private reader now splits on LF boundaries; three Unicode regression cases failed before the fix and all 89 control tests passed afterward. An independent Astra xhigh review found no outstanding issues. The new reader parsed all 2,638 unchanged records and reproduced both scores (samples SHA256 6f3270b7c44ce5e2954aedf37fef4587906cfd5db15a4fc12b151ee7e12772ec). The failed step remains unqualified and preserved; the strict retry below supplies the reusable baseline. This is baseline evidence, not a result for this PR's FP8 candidate.

The strict shared TP8 BF16 baseline retry, step 23512.62, is now qualified and independently verified at source 8c87c333b84c85908b1d11f0044457692277c6f3 with the unchanged8860/00ac configuration. It completed all 1,319 questions / 2,638 filter records, scoring 1265/1319 strict-match (95.906%) and 1264/1319 flexible-extract (95.830%), with zero empty/invalid responses. The one filter difference is preserved: a time answer ending 2:00 pm yields strict 2 and flexible 00; no oracle was changed. Live origins covered10 processes and33 library hashes, complete and descriptor-closed before full evaluation. Final metrics, all234 bundle content hashes,406 package pins,17 native identities and same-step teardown were verified; Slurm finished COMPLETED0:0. Bundle SHA256: 2bd0b7c872ada3fd90cfcee948e2f8661e1639e3870b09afc362a5e5e2e36f8a. This supplies the exact-base TP8 BF16 reference, not an FP8 candidate, TP4 or long-context model result.

The earlier JSONL-v2 seal 8dacc9329b013b23cd0387ee815947ee9faf1ce98727afc7b058cb59b1f57a76 remains preserved. The current private origin-v3 controls were independently reviewed, sealed and frontend-staged with all85 hashes verified (manifest SHA256 5a8348e28196d71c491ca1d5aba1b3ce93ad03a27df17f1b1cb301ca323839c1). Each independently started model server now has a truthful zero-question origin pause, bound live PID/source/step receipts, a separate full1319 continuation gate, and cleanup-only handling after revocation. Unknown descriptor closure holds the existing server/watchdog without inference or voluntary teardown; Slurm hard limits remain unchanged. Deadline and callback-race failures are preserved, and all163 final CPU checks passed. These controls have not yet produced an FP8/TP4/long-context model result. Production source remains e2b15a1341df1bca125ee42bb15fb1dc659937d8; no source commit was needed. September11 recovery epoch 20260911T181713Z retires allocation 23512 as terminal FAILED (124:0) and denies every execution grant. The remaining TP4/TP8 model and long-context arms require a separately authorized fresh resource plan and control binding; old steps, PIDs, wrappers and continuation records are historical non-grants. Scheduler or reboot evidence is not treated as direct descriptor-closure proof. The preserved correctness/performance runs and separately scoped shared baseline remain as reported above.

Recovery verification reran 15 existing package/config CPU regression cases: 15 passed, 0 failed/errors/skipped (48 unrelated cases deselected). Independent Astra xhigh review confirmed the 406 top-level package inventory plus active-version checks are already present; no duplicate source fix or commit was needed. All 84 immutable control payload hashes remained unchanged under the same origin-v3 manifest. This verification grants no model execution and does not qualify the pending candidate arms.

FP8 TP8 and both TP4 model arms, and long-context serving remain unexecuted. No model-quality equivalence, serving gain or production qualification is claimed. This PR remains a draft for human review and coordination with #47665.

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[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @venkywonka.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork