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feat: add configurable spline FPM regression - #347

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diffractiongoo:codex/fpm-spline-regression
Sep 30, 2026
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tedzhouhk merged 9 commits into
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diffractiongoo:codex/fpm-spline-regression

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@diffractiongoo

@diffractiongoo diffractiongoo commented Sep 29, 2026 •

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Summary

Latency can pass through several regimes with different slopes, which a single linear fit cannot capture. Add an opt-in, continuous additive spline through the canonical ForwardPassPerfModelConfig interface. Linear remains the default regression fit.

estimation_mode: fpm_regression
estimator_config:
  fpm_regression:
    fit:
      kind: spline
      spline:
        knots_per_axis: 2
        search:
          kind: adaptive
          window: 16
          trigger: 8
          tolerance: 0.05
          absolute_tolerance_ms: 1.0
          cooldown: 64

Omitting the spline controls resolves to these defaults. Periodic search uses search: {kind: periodic, step: 64}. Both policies support two or three knots per axis and tunable controls.

  • Learn continuous segments with a free intercept and nonnegative slopes; slopes may decrease between segments. Between knot searches, update centered sufficient statistics for each insertion and actual eviction, then solve constrained NNLS.
  • Share one retained sample set with the existing linear fit. Require a finite prediction from that linear arm for the same query before serving either path. Use linear predictions during spline warmup, numerical unavailability, and outside the current retained feature bounds. Store readiness requires the linear fit; spline.ready remains an independent component diagnostic. The initial knot search occurs after max(32, min_observations) accepted observations; default periodic searches occur at 32, 64, 128, and onward.
  • Adaptive search counts excessive errors in a rolling window using the incoming observation's raw prediction before updating the fit. Its accepted-observation clock is separate from the insertion/eviction clock used by fit.rebuild_interval. Queries and rejected observations do not advance either clock.
  • Rust owns defaults and validation. Python, CLI/YAML overrides, provenance, caching, and saved configurations preserve the same controls. The linear alias normalizes to standardized_nnls; existing linear serialized output remains unchanged. Spline diagnostics expose initialization, readiness, searches, and numerical recovery.

Saved configurations preserve settings, not learned state; cold-regression restrictions in offline simulation remain. Axis interactions and outlier-robust fitting are outside this change. Rust consumers using exhaustive fit-enum matches or full literals for the expanded configuration/diagnostic structs may need to update them.

Reviewer guide (medium risk): start with crates/core/src/perfmodel/fpm/regression/spline.rs for scheduling and fallback behavior, then spline/fit.rs and spline/recursive.rs for fitting and recovery. estimator.rs, model.rs, and the Python binding carry the public contract. Rust/Python tests cover numerical oracles and caller transport; CODEOWNERS changes register the new caller test. API examples and the full validation report explain behavior and limitations.

Validation

The coverage guard was checked against the pre-guard serving method at d3f92e59 on 15 dataset prefixes and 163,540 inputs per policy, evaluating both methods and the shared linear arm on identical trained state before each update. Guarded availability matched the shared linear arm on every query; every remaining forecast was bit-for-bit unchanged. It removed 7,043 periodic and 7,013 adaptive forecasts, leaving 154,149 and 153,994 available, respectively. Each policy has its own sampler realization; these are coverage checks, not an independent accuracy holdout.

Five paired release trials across those prefixes measured input-weighted means of per-case trial medians for prediction/update cost: 8.3105 → 8.3142 µs/input periodic (+0.045%) and 3.9408 → 3.9458 µs/input adaptive (+0.129%), within local timing variation. Timing includes per-operation timer overhead and excludes cloning, destruction, parsing/feature extraction, Python/FFI, and full-engine costs.

The following historical results predate the coverage guard and are preserved for context. Their numerical values and available-row cohorts must not be presented as measurements of the guarded behavior. The 2026-09-25 production-code replay covered 15 existing local dataset prefixes and 163,540 observations, preserving input order and predicting before each update. Stores retained at most 64 samples; scoring started after 64 accepted observations per store.

Historical per-dataset MAPE (%), lower is better. Both spline columns use two knots per axis; adaptive uses a 1 ms absolute-error floor and a 64-observation cooldown. These are production implementation measurements; they differ from the earlier research-harness results.

Dataset / hardware / backend / parallelism Linear baseline Periodic search, step 64 Adaptive 16/8/5%
MiniMax-M2.7 / B200 / vLLM / TEP4 65.8546 27.6780 27.3617
MiniMax-M2.7 / H200 / vLLM / TP4 0.8712 5.3100 1.6323
MiniMax-M2.7 / H200 / vLLM / TEP4 19.4826 12.1838 12.2066
DeepSeek-V4-Flash-0731 / B200 / vLLM / DEP4 24.7329 9.7790 8.1941
DeepSeek-V4-Flash-0731 / B200 / vLLM / TEP4 19.4820 6.6720 7.7206
DeepSeek-V4-Pro / B200 / vLLM / DEP8 4.7521 4.5773 4.5888
DeepSeek-V4-Pro / B300 / SGLang / DEP8 2.6890 2.0163 2.1057
DeepSeek-V4-Pro / GB300 / vLLM / DEP8 0.1628 0.1586 0.1620
DeepSeek-V4-Pro / GB300 / vLLM / TEP8 0.1340 0.1243 0.1251
Kimi-K3 / GB300 / vLLM / TEP8 2.3199 1.4620 1.5619
GLM-5.2-NVFP4 / B200 / SGLang / TP8 0.6316 0.5999 0.6264
GLM-5.2-NVFP4 / B200 / vLLM / DEP8 11.3469 6.4263 6.5370
GLM-5.2-NVFP4 / B200 / vLLM / TEP8 14.7343 6.9015 7.6899
GLM-5.2-NVFP4 / GB200 / vLLM / DEP16 2.3195 1.7002 1.8485
MiniMax-M3-NVFP4 / B200 / vLLM / TP4 4.0131 3.8388 4.0899
Equal-dataset mean MAPE 11.5684 5.9619 5.7634
Observation-weighted MAPE 5.4900 3.5771 3.2405

The accuracy comparison uses 151,600 rows where all six tested methods produced forecasts, out of 161,223 eligible rows. It does not establish accuracy on the additional spline forecasts. On each method's own available rows, equal-dataset MAPE was 11.7526% linear, 55.9513% adaptive, and 55.5054% periodic, using different cohorts. That replay exposed substantial overprediction in the B200 MiniMax-M2.7 TEP4 case: adaptive and periodic MAPE reached 780.1663% and 770.8220% on their available rows. A retained-feature bounding box does not guarantee accurate interpolation. The linked validation report documents per-dataset coverage and the scoring protocol.

Mean CPU cost per input was 1.5802 µs linear, 8.0693 µs periodic, and 3.9200 µs adaptive. Timing used Rust 1.97.1 release builds on macOS/arm64, with seven alternating measured pairs per dataset. Adaptive and periodic cost 2.460× and 5.200× their paired linear baselines. Default-linear cost changed by +0.159%; no dataset exceeded a 10% slowdown. These are CPU store prediction/update costs, including retention, knot search, and numerical recovery; they exclude feature extraction, Python/FFI transport, and full-engine overhead.

Benchmark evidence comes from the implementation in 69210d4e, against linear baseline 2bd9966d. The knot-search, coefficient-fitting, and retention logic are unchanged, but the subsequent serving guard suppresses queries whose shared linear prediction is unavailable. These historical benchmarks were not rerun after integration onto main; the separate guard validation above compares identical model state. Prefixes were previously inspected, not an untouched holdout. Independently constructed samplers retain existing randomized tie behavior. Raw datasets, binaries, and research artifacts under work/ are private and unpublished; these measurements cannot be independently reproduced from this repository alone.

Earlier local validation at ba4826ce8fe39771277c9e4ab91e2fbf184c5394: 708 tests passed: 131 Rust FPM, 14 external Rust API, 130 Python API/binding, 37 existing forward-pass/regression, 10 caller transport, and 386 across both required engine-step and compile-engine parity suites. Python checks used the matching release native build. The parity tree and frozen goldens are unchanged from the base.

Coverage includes independent piecewise-linear numerical oracles, recursive-versus-batch checks through eviction and rank loss, constant axes and large ranges, initialization and trigger boundaries, raw prediction-before-update, query immutability, retained-bound changes, invalid configuration, and saved-config/caller isolation. Pre-commit hooks, documentation links, complete ownership coverage, and generated CODEOWNERS consistency checks passed.

Exact local validation commands
cargo test --offline -p aisimulate-core --lib perfmodel::fpm

PYO3_PYTHON="$PWD/python/aisimulate/.venv/bin/python" \
  CARGO_TARGET_DIR="$PWD/target" \
  cargo test --offline --manifest-path crates/tests/public-api/Cargo.toml

python/aisimulate/.venv/bin/python -m pytest -q -p no:timeout \
  -c python/aisimulate/pytest.ini \
  python/aisimulate/tests/unit/sdk/test_fpm_spline.py \
  python/aisimulate/tests/cross_package/test_core_public_api.py

python/aisimulate/.venv/bin/python -m pytest -q -p no:timeout \
  tests/test_spline_estimator_config.py

python/aisimulate/.venv/bin/python -m pytest -q -p no:timeout \
  -c python/aisimulate/pytest.ini \
  python/aisimulate/tests/unit/sdk/test_rust_engine_step.py \
  -k 'forward_pass or regression'

python/aisimulate/.venv/bin/python -m pytest -q -p no:timeout \
  -c python/aisimulate/pytest.ini \
  crates/core/parity_tests/perfmodel/test_engine_step_parity.py \
  crates/core/parity_tests/perfmodel/test_compile_engine_parity.py

Follow-up 5af7b4c4be6f15907e0d5b304c5c65282c9d28b7 requires shared linear availability for serving and readiness, updates Rust/Python contracts, and covers abstention and recovery. Validation: 133 Rust FPM tests and 403 Python/native checks passed, including the 17 spline API tests and both required parity suites (386 cases), using a matching release native build. Frozen goldens remain unchanged. Rust formatting, Ruff, and documentation-link checks passed. Codex reviewed the guard changes. Related PR: #297 (merged). No linked issue.

Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>
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🔀 Multi-repo context ai-dynamo/dynamo, ai-dynamo/aiconfigurator

Linked repositories findings

ai-dynamo/dynamo

  • Dynamo pins AISimulate to 0.13.0.dev202609270000000058 in both Python and Rust, so that published artifact must contain the new spline schema and exports. [::ai-dynamo/dynamo::] pyproject.toml:17; Cargo.toml:59-60
  • Legacy replay canonicalization only maps fixed fields before constructing ForwardPassPerfModelConfig; it does not carry estimator_config, so legacy replay metadata can drop spline settings. [::ai-dynamo/dynamo::] components/src/dynamo/replay/config.py:26-67
  • Current router/planner paths explicitly preserve nested estimator_config, including role-specific controls. [::ai-dynamo/dynamo::] components/src/dynamo/router/simulation/provider.py:154-160; components/src/dynamo/planner/core/perf_model/ais_adapter.py:291-292,378-383
  • Existing tests assert estimator-config preservation but contain no spline-specific cases, leaving the new nested schema untested downstream. [::ai-dynamo/dynamo::] components/src/dynamo/router/tests/test_router_sweep_config_provider.py:485-515; components/src/dynamo/planner/tests/unit/test_ais_perf_config.py:69-182

ai-dynamo/aiconfigurator

  • No spline, Spline, estimator_config, or standardized_nnls references were found. Its wrapper remains a legacy dictionary-to-Rust facade with from_native, best_available, and from_regression. [::ai-dynamo/aiconfigurator::] aic-core/src/aiconfigurator_core/sdk/rust_engine_step.py:90-205

📝 Summary

Risk: Medium. The three areas that need the most human attention are spline fitting and recursive statistics, prediction fallback and readiness behavior, and the expanded Rust/Python configuration and diagnostics contracts.

Changes and public contracts

  • Adds opt-in RegressionFitKind::Spline. Linear remains the default, and linear aliases standardized_nnls.
  • Adds additive spline fitting with two or three knots per axis and periodic or adaptive knot searches. Each spline store shares accepted samples with its linear fit.
  • A spline forecast requires an available linear prediction. The model uses the spline within retained feature bounds when it is ready; otherwise, it uses the linear prediction. Spline readiness alone does not make the store ready.
  • Adds public Rust configuration and diagnostics types. Python normalization resolves spline defaults before validation and serialization. Saved configurations preserve settings, not learned samples or state.
  • Offline simulation’s cold-regression restrictions remain. Rust consumers with exhaustive enum matches or full struct literals for expanded structs may need updates.

Evidence and merge readiness

The author reports 708 local tests passed at the cited revision, followed by 132 Rust FPM tests and formatting, Ruff, and documentation-link checks in a follow-up. These reported checks include configuration, caller transport, and parity tests. The supplied source confirms the linear-availability prediction guard and its readiness implications.

The author also reports production-code replay across 15 dataset prefixes and 163,540 observations. On rows where all six methods forecasted, equal-dataset mean MAPE was 11.5684% for linear, 5.9619% for periodic spline, and 5.7634% for adaptive spline. This comparison does not establish accuracy on additional spline forecasts. On each method’s own available rows, reported MAPE was 55.5054% for periodic and 55.9513% for adaptive, with substantial overprediction in the B200 MiniMax-M2.7 TEP4 case. Reported mean CPU cost per input was 1.5802 µs for linear, 8.0693 µs for periodic spline, and 3.9200 µs for adaptive spline. The measurements exclude feature extraction, Python/FFI transport, and full-engine overhead. The benchmarks were not rerun on current main, and the prefixes were previously inspected rather than an untouched holdout.

Technical evidence includes implementation descriptions, reported test results, and replay measurements. Independent validation on an untouched holdout is not established. CI status and current review findings were not supplied, so review severity counts are unavailable. The bot review is not an approval. Merge readiness is not established.

Walkthrough

The forward-pass performance model adds optional learned-knot spline regression with periodic or adaptive search. The change adds configuration validation, prediction fallbacks, per-store diagnostics, public API support, and tests and documentation for configuration and caller-side serialization.

Changes

Spline regression

Layer / File(s) Summary
Spline configuration and public contract
crates/core/src/perfmodel/fpm/estimator.rs, crates/core/src/lib.rs, crates/core/src/perfmodel/fpm/mod.rs, crates/core/src/perfmodel/mod.rs, crates/core/src/perfmodel/py.rs, crates/tests/public-api/src/lib.rs, python/aisimulate/tests/cross_package/test_core_public_api.py, python/aisimulate/tests/unit/sdk/test_fpm_spline.py, docs/core-api.md, python/aisimulate/src/aisimulate_core/sdk/rust_engine_step.py
RegressionFitKind adds spline and accepts linear as an alias for standardized_nnls. Spline settings define knot count and periodic or adaptive search controls, with default resolution and validation. The types and diagnostics are re-exported, and configuration normalization resolves defaults before validation and serialization. Tests and documentation describe the configuration contract.
Spline fitting and search engine
crates/core/src/perfmodel/fpm/regression/spline/fit.rs, crates/core/src/perfmodel/fpm/regression/spline/recursive.rs, crates/core/src/perfmodel/fpm/regression/spline.rs, crates/core/src/perfmodel/fpm/regression/spline/tests.rs
The fitter builds an additive piecewise-linear model with nonnegative segment slopes and learned knots. Recursive statistics support insertion, removal, rebuilding, and batch-fit fallback. The spline store schedules searches, tracks retained-feature bounds, and uses the linear fit outside those bounds or before spline readiness. Tests cover fitting, search, fallback, and numeric cases.
Regression-store integration and diagnostics
crates/core/src/perfmodel/fpm/regression.rs, crates/core/src/perfmodel/fpm/model.rs, crates/core/src/perfmodel/fpm/tests.rs, crates/tests/public-api/src/lib.rs, docs/core-api.md, python/aisimulate/src/aisimulate_core/sdk/rust_engine_step.py, python/aisimulate/tests/unit/sdk/test_fpm_spline.py
RegressionStore dispatches operations to the selected linear or spline store. Forward-pass model construction passes the full fit configuration, and diagnostics include optional spline state. Tests cover store clocks and serialization reloads. Documentation distinguishes store readiness, spline readiness, and the search and rebuild clocks.
Caller configuration transport and replay evidence
tests/test_spline_estimator_config.py, .github/codeowners/areas.yaml, CODEOWNERS, docs/fpm-recursive-regression.md
Tests cover estimator settings through replay serialization, role-specific configuration, recommendation candidates, and resolver caching. They also check the offline-readiness error for insufficient training observations. The documentation adds production replay results and timing comparisons, and ownership rules include the new configuration test.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~60 minutes

Merge Risk: ⚪ Minimal · up to 5af7b

The opt-in spline behavior retains linear availability safeguards, and saved configurations restart without learned state. No actionable merge-blocking risk is established; merge after normal checks.

🚥 Pre-merge checks | ✅ 7 | ❌ 1

❌ Failed checks (1 warning)

Check name Status Explanation Resolution
Modeling And Data Evidence ⚠️ Warning The PR provides strong provenance and reproducible unit oracles for spline formulas and scheduling, including hand-derived surfaces, exact slopes/SSE/predictions, and recursive-versus-batch comparison… Add a committed or immutably published machine-readable evidence bundle and replay harness. Include the exact input/source/binary hashes, baseline and candidate revisions, per-dataset predictions or aggregates, coverage and missingness chec…
✅ Passed checks (7 passed)
Check name Status Explanation
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.
Cross-Layer Contract ✅ Passed All changed spline contracts have cross-layer coverage. Rust defines, defaults, validates, resolves, re-exports, and serializes the new fit controls and diagnostics. The Python binding preserves the m…
Compatibility Boundaries ✅ Passed Compatibility boundaries remain intact. Rust and Python use the same canonical spline field names, defaults, validation, normalization, reload, and diagnostics; the PR adds cross-surface tests for the…
Review Evidence ✅ Passed The complete PR description names exact cargo and pytest commands with results, including 708 earlier tests and 133 Rust FPM plus 403 Python/native checks. It covers negative and boundary cases such a…
Title check ✅ Passed The title precisely identifies the behavioral change: configurable spline regression for the FPM.
Description check ✅ Passed The description is mostly complete and documents the problem, behavior, consumers, review risks, public contract, validation commands, boundary cases, performance evidence, limitations, and related wo…
Full details: Modeling And Data Evidence

Explanation

The PR provides strong provenance and reproducible unit oracles for spline formulas and scheduling, including hand-derived surfaces, exact slopes/SSE/predictions, and recursive-versus-batch comparisons. However, its production MAPE, coverage, and timing claims are not reproducible from the PR. The added validation report explicitly states that the input data, forecasts, hashes, and harness are private, that no immutable artifact bundle is published, and that the measurements cannot be independently reproduced from the repository. The report also states that the checked-in tests do not validate those workload results. Markdown tables and anomaly notes do not replace a machine-readable, reproducible before/after data artifact.

Resolution

Add a committed or immutably published machine-readable evidence bundle and replay harness. Include the exact input/source/binary hashes, baseline and candidate revisions, per-dataset predictions or aggregates, coverage and missingness checks, anomaly checks, and the commands needed to regenerate the reported MAPE and timing results. Rerun the comparison on the reviewed integrated revision, or clearly scope the evidence to a deterministic held-out fixture. Keep the checked-in independent numerical oracles for formula and selection behavior.


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@diffractiongoo
diffractiongoo marked this pull request as ready for review September 29, 2026 23:40
@diffractiongoo
diffractiongoo requested review from a team as code owners September 29, 2026 23:40

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Actionable comments posted: 3


  • 🪄 Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @crates/core/src/perfmodel/fpm/regression/spline.rs:
- Around line 313-315: Update SplineStore::is_ready to report ready only when
linear_fit is present, since that fit serves queries outside the retained spline
bounds; keep the spline component’s readiness reporting unchanged. Add a test
that creates a spline-ready, linear-unready store and verifies a query outside
its bounds.

Review comments at @docs/core-api.md:
- Around line 374-393: Add a Rust source-compatibility note alongside the spline
configuration example in the core API documentation. State that callers must add
`spline: None` or use `..Default::default()` in `RegressionFitConfig` and
`ForwardPassRegressionStoreDiagnostics` struct literals, and handle
`RegressionFitKind::Spline` in exhaustive matches.

Review comments at @docs/fpm-recursive-regression.md:
- Around line 619-643: Update the validation and timing evidence section to
identify the exact source commit used for the reported tables and disclose that
timing predates the rebase onto current main. Replace the local artifact-path
references with an immutable published location, or explicitly state that the
artifacts are private and the results are not reproducible from this repository;
apply the same disclosure to the absent artifact paths cited in the spline
module documentation. Keep predictive-accuracy and compatibility claims within
the evidence available, and satisfy REVIEW.md’s reproducible before-and-after
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python/aisimulate/tests/cross_package/test_core_public_api.py

[info] 337-337: use jsonify instead of json.dumps for JSON output
Context: json.dumps(request)
Note: [CWE-116] Improper Encoding or Escaping of Output.

(use-jsonify)


[info] 344-344: use jsonify instead of json.dumps for JSON output
Context: json.dumps(normalized)
Note: [CWE-116] Improper Encoding or Escaping of Output.

(use-jsonify)


[info] 347-347: use jsonify instead of json.dumps for JSON output
Context: json.dumps(saved)
Note: [CWE-116] Improper Encoding or Escaping of Output.

(use-jsonify)


[info] 395-395: use jsonify instead of json.dumps for JSON output
Context: json.dumps(request)
Note: [CWE-116] Improper Encoding or Escaping of Output.

(use-jsonify)


[info] 414-414: use jsonify instead of json.dumps for JSON output
Context: json.dumps(request)
Note: [CWE-116] Improper Encoding or Escaping of Output.

(use-jsonify)

python/aisimulate/tests/unit/sdk/test_fpm_spline.py

[info] 83-83: use jsonify instead of json.dumps for JSON output
Context: json.dumps(resolved)
Note: [CWE-116] Improper Encoding or Escaping of Output.

(use-jsonify)

🪛 Clippy (1.98.1)
crates/core/src/perfmodel/fpm/regression/spline.rs

[warning] 134-134: this if statement can be collapsed

(warning)

crates/core/src/perfmodel/fpm/regression.rs

[warning] 36-36: large size difference between variants

(warning)

crates/core/src/perfmodel/fpm/regression/spline/fit.rs

[warning] 43-43: the loop variable axis is used to index x

(warning)


[warning] 62-62: the loop variable i is used to index passive

(warning)


[warning] 87-87: the loop variable j is only used to index a

(warning)


[warning] 211-211: the loop variable j is only used to index norms

(warning)


[warning] 234-234: the loop variable i is used to index gram

(warning)


[warning] 235-235: the loop variable j is only used to index gram

(warning)


[warning] 356-356: this if statement can be collapsed

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[warning] 357-357: this if statement can be collapsed

(warning)


[warning] 358-358: this if statement can be collapsed

(warning)


[warning] 382-382: this if statement can be collapsed

(warning)

crates/core/src/perfmodel/fpm/regression/spline/recursive.rs

[warning] 119-119: the loop variable i is used to index delta

(warning)


[warning] 158-158: the loop variable i is used to index delta

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[warning] 204-204: the loop variable i is used to index z

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🔀 Multi-repo context ai-dynamo/dynamo, ai-dynamo/aiconfigurator

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ai-dynamo/dynamo

  • AIS configuration is passed through ForwardPassPerfModelConfig(**config).to_dict(), preserving nested estimator controls in CLI, planner, router, mocker, and replay paths. [::ai-dynamo/dynamo::]
  • Planner configuration validates and normalizes through the upstream SDK, then stores the resulting dataclass; new spline fields therefore require a compatible AISimulate SDK. components/src/dynamo/planner/config/planner_config.py:119-133 [::ai-dynamo/dynamo::]
  • Planner’s _merge_estimator_controls recursively preserves unknown/future nested fields, so spline fit/search settings should survive default injection. components/src/dynamo/planner/core/perf_model/ais_adapter.py:292-294,754-763 [::ai-dynamo/dynamo::]
  • Router prediction transport dynamically selects top-level SDK fields and deep-copies estimator_config; no spline-specific filtering was found. components/src/dynamo/router/simulation/provider.py:139-184 [::ai-dynamo/dynamo::]
  • Replay’s Rust boundary deserializes the complete config as ForwardPassPerfModelConfig, so spline configs cross replay only when the linked SDK supports them. lib/mocker/src/common/protocols.rs:1177-1200 [::ai-dynamo/dynamo::]
  • Existing planner tests cover nested fpm_regression.fit and estimator-control round trips, but no spline-specific consumer or diagnostics usage was found. components/src/dynamo/planner/tests/unit/test_ais_perf_config.py:42-70 [::ai-dynamo/dynamo::]

ai-dynamo/aiconfigurator

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🔇 Additional comments (18)
crates/core/src/perfmodel/fpm/estimator.rs (1)

128-199: LGTM!

Also applies to: 211-214, 223-223, 298-306, 338-338, 355-421, 477-638

crates/core/src/lib.rs (1)

44-53: LGTM!

crates/core/src/perfmodel/fpm/mod.rs (1)

50-50: LGTM!

crates/core/src/perfmodel/mod.rs (1)

53-59: LGTM!

crates/core/src/perfmodel/py.rs (1)

1906-1906: LGTM!

python/aisimulate/tests/cross_package/test_core_public_api.py (1)

302-417: LGTM!

python/aisimulate/tests/unit/sdk/test_fpm_spline.py (1)

1-192: LGTM!

python/aisimulate/src/aisimulate_core/sdk/rust_engine_step.py (1)

112-121: LGTM!

Also applies to: 251-257, 396-405

crates/core/src/perfmodel/fpm/regression/spline/fit.rs (1)

1-394: LGTM!

crates/core/src/perfmodel/fpm/regression/spline/recursive.rs (1)

1-329: LGTM!

crates/core/src/perfmodel/fpm/regression/spline/tests.rs (1)

1-569: LGTM!

crates/core/src/perfmodel/fpm/regression.rs (1)

10-100: LGTM!

crates/core/src/perfmodel/fpm/model.rs (1)

21-24: LGTM!

Also applies to: 124-126, 131-131, 138-138, 154-159, 171-171, 198-198, 303-310, 324-324, 363-363, 1186-1262, 1306-1306

crates/core/src/perfmodel/fpm/tests.rs (1)

176-176: LGTM!

crates/tests/public-api/src/lib.rs (1)

352-427: LGTM!

Also applies to: 651-656

.github/codeowners/areas.yaml (1)

36-36: LGTM!

Also applies to: 182-183

CODEOWNERS (1)

49-49: LGTM!

Also applies to: 197-197

tests/test_spline_estimator_config.py (1)

1-252: LGTM!

Comment thread docs/core-api.md Resolved
Comment thread docs/fpm-recursive-regression.md Resolved

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  • 🪄 Fix CodeRabbit comments on this PR
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Review comments at
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- Around line 411-412: Add a store-level assertion in the focused test for
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Linked repositories findings

ai-dynamo/dynamo

  • canonical_upstream_config reconstructs configs from a fixed identity-field set and does not forward estimator_config; legacy replay inputs without model can therefore lose spline settings. [::ai-dynamo/dynamo::] components/src/dynamo/replay/config.py:26-67
  • Planner bootstrapping uses that lossy conversion when engine_args.ais_perf_config is absent. [::ai-dynamo/dynamo::] components/src/dynamo/replay/planner.py:163-177
  • Other paths preserve complete canonical estimator config: router transport deep-copies nested config, and current mocker tests assert estimator_config propagation. [::ai-dynamo/dynamo::] components/src/dynamo/router/simulation/provider.py:72-113; components/src/dynamo/mocker/tests/unit/test_config.py:736-749
  • Dynamo pins AISimulate to 0.13.0.dev202609270000000058; that artifact must contain the new spline schema and exports. [::ai-dynamo/dynamo::] pyproject.toml:17; Cargo.toml:59-60

ai-dynamo/aiconfigurator

  • AIConfigurator remains at compatibility version 0.12.0 and exposes the legacy RustForwardPassPerfModel; no new spline estimator configuration is present. [::ai-dynamo/aiconfigurator::] pyproject.toml:5-10; aic-core/pyproject.toml:5-13; aic-core/src/aiconfigurator_core/sdk/rust_engine_step.py:90-205
  • The repository explicitly directs new integrations to AISimulate, so it is not a runtime consumer of this PR’s new API. [::ai-dynamo/aiconfigurator::] README.md:8-15

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Thanks for the thorough write-up and the unusually honest validation section. The implementation itself looks solid: the NNLS/KKT checks, recursive-vs-batch recovery, config ownership in Rust (resolve_defaults in both best_available and normalize_config), strict serde, and the linear wire format all look right. CI is green.

I'm requesting changes for one behavioral issue, which your own numbers show:

The spline serves predictions where the linear arm deliberately abstains, and those predictions are catastrophically wrong.

From the validation tables, spline methods cover ~159k rows versus ~152k for linear. Only 151,600 rows are common. Subtracting the common-row contribution from the own-row pooled MAPE gives this rough estimate for the ~7k spline-only rows:

Method Extra rows Implied MAPE on extra rows
Periodic, 2 knots 7,601 ~1,449%
Adaptive, 2 knots 7,382 ~1,528%
Periodic, 3 knots 6,919 ~1,435%
Adaptive, 3 knots 7,436 ~1,563%

That's why own-row MAPE jumps from 5.6% (linear) to 72–77% (spline). The mechanism is BucketedSpline::is_ready / predict. When the linear NNLS lands on a zero-slope face, e.g. a negative overall covariance (the spline_only_readiness_has_retained_domain_coverage case), the linear fit returns None and the store used to report not-ready. The caller then got None and could fall back or skip. Now the spline claims readiness and answers anyway. The favorable common-row table (11.57% -> 5.76%) is not what a user of fit.kind: spline would actually get.

Suggested fix: serve the spline only when the linear arm is also available. Keep is_ready() equal to linear readiness, and in predict() use the spline branch only when linear_fit.is_some(). Then spline coverage equals linear coverage, the shipped behavior matches the common-row evidence, and this caveat also goes away: "a ready store can return None inside a query" (the new readiness caveat in the Rust/Python docs). If there's a reason to keep spline-only readiness, please show acceptable accuracy on those extra rows before this ships, even behind opt-in.

Smaller items (non-blocking):

  1. The accuracy/timing numbers were measured before the move onto main and not rerun on ba4826ce/939b4875. After the gating change, please rerun at least the coverage/own-row table on the final head.
  2. Even on common rows, H200 MiniMax-M2.7 TP4 regresses 0.87% -> 5.31% (periodic, 2 knots) / 1.63% (adaptive). That's fine for an opt-in feature, but worth one sentence in the user-facing core-api.md section so people don't flip it on globally.
  3. Adding spline to ForwardPassRegressionStoreDiagnostics and RegressionFitConfig breaks downstream Rust struct literals and exhaustive matches, as you note. Consider #[non_exhaustive] on the new SplineSearchConfig/diagnostics types so future knobs don't break callers again.

Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>
Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>
Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>
Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>

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Thanks, Harry. I agree that spline should not introduce forecasts where its shared linear model abstains. Store readiness now requires a usable linear fit, and each spline query requires a finite prediction from that same linear arm. The spline component's diagnostic readiness remains separate. This preserves linear availability without claiming that availability guarantees accuracy.

I addressed the three smaller items:

  • Reran production accuracy and coverage on the final numerical sources at e5433b2e, after the main integration and availability guard. The updated report includes all 15 datasets, coverage, and variation across three paired trials.
  • Added the H200 MiniMax-M2.7 TP4 accuracy warning to core-api.md, including the historical regression, and guidance to evaluate spline per deployment before enabling it.
  • Marked the new SplineSearchConfig enum and variants, and ForwardPassSplineDiagnostics, as #[non_exhaustive]. Added policy constructors and downstream API tests. Configuration defaults and serialized representation are unchanged.

The fresh replay retains every input, including the latency spikes. It scores predictions before updates, after 64 accepted observations per store. All three methods use identical retained samples and have exactly the same available-query cohort within each trial:

Three-trial mean MAPE Linear Periodic 64 Adaptive 16/8/5%
Observation-weighted 5.7308% 3.4254% 3.3518%
Equal-dataset 11.9023% 5.9978% 5.9884%

The table averages the three per-trial metrics. Common coverage is 151,484–152,032 of 161,223 eligible rows per trial, averaging 94.1057%. These are conditional errors on available forecasts; abstentions are reported, not assigned zero error. MiniMax/B200/TEP4 has only 46.97% coverage, with MAPE of 70.16%, 30.79%, and 30.91%, respectively. Periodic still regresses on H200/TP4: 2.37% versus 1.17% linear. Adaptive averages 1.04% there but also regresses in one trial.

The MiniMax/B200/TEP4 decode dataset has a median latency of 7.26 ms and a 99th percentile of 11.65 ms, yet contains 42 observations above 1,000 ms, including four above 5,000 ms (maximum 8,363.71 ms), with abrupt spikes at nearly unchanged attention/MoE features. None of the other 14 tested datasets contains an observation above 1,000 ms after the same warmup, making this an unusually spiky case within our evaluation. This comparison does not establish that the spikes are measurement artifacts or that comparable stalls cannot occur in production; determining their cause and deployment relevance would require additional telemetry.

The saved MiniMax/B200/TEP4 sequence shows multi-second observations followed by inflated predictions from both fits. A separate diagnostic that exposes normally rejected intercept-only linear fits scores every mature row in that dataset: 924.09% linear, 930.34% periodic, and 932.98% adaptive MAPE. Those are counterfactual scores, not production results, and they do not establish the spikes as the sole cause. They show that both methods can fail badly; the lower production MAPE does not justify spline-only forecasts on the abstained rows. The shared-linear gate therefore remains necessary, and linear remains the default.

Validation: 133 FPM Rust tests, 14 downstream API tests, two compile-fail doctests, formatting, documentation links, and the audited release replay passed. The gate also previously passed 403 Python/native checks with a matching native build, including the required engine parity suites. Existing linear goldens are unchanged.

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Reviewed fbefd79. No new blocking findings. The shared-linear availability guard addresses the earlier coverage issue: spline predictions require a finite linear prediction for the same query, and store readiness follows the linear arm. Linear remains the default.

Validation: 133 Rust FPM tests and 141 Python/native public-API and caller-configuration tests passed locally with this head built. An independent SciPy NNLS comparison across 1,200 fixed-knot cases found no objective mismatch within tolerance. Fast CI and Full CI passed on the reviewed head; all six review threads are resolved. The production accuracy figures remain author-reported, with the documented coverage and workload-specific limitations.

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Thanks, this addresses the blocking issue. Verified at fbefd79:

  • BucketedSpline::is_ready() now equals linear readiness, and predict() returns None before the spline branch unless the shared linear arm produces a prediction for the same query. Spline coverage can no longer exceed linear coverage.
  • The rerun on the final sources shows identical available cohorts for all three methods, with the spline still improving the paired errors (observation-weighted 5.73% -> 3.43% / 3.35%). The H200 TP4 regression and MiniMax/B200/TEP4 spike caveats are documented in core-api.md and the report.
  • #[non_exhaustive] plus the periodic()/adaptive() constructors, with compile-fail doctests, cover the extensibility point.

CI is green. LGTM.

Preserve registration-aware FPM resolution and resolve spline defaults before validation. Merge legacy inputs before applying defaults and cover canonical and legacy spline round trips. Retain both public export sets and regenerate CODEOWNERS.

Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>
Retain spline configuration and diagnostics alongside the new FPM coverage and resource APIs from main. Preserve the shared-linear serving gate, numerical implementations, and recursive-regression design report.

Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>
@tedzhouhk
tedzhouhk enabled auto-merge (squash) September 30, 2026 20:59
@tedzhouhk
tedzhouhk merged commit 66f4457 into ai-dynamo:main Sep 30, 2026
67 checks passed
tianhaox added a commit to tianhaox/aisimulate that referenced this pull request Oct 1, 2026
Brings in the FPM decoupling / self-service onboarding stack (ai-dynamo#238, ai-dynamo#248,
ai-dynamo#347), the output adapters (ai-dynamo#334) and the CI changes (ai-dynamo#349, ai-dynamo#351, ai-dynamo#353,
ai-dynamo#354, ai-dynamo#330, ai-dynamo#319).

Conflict resolutions:

- ENGINE_SPEC_SCHEMA_VERSION: upstream claimed 25 for the FPM decoupling
  selector; decode CP is renumbered to 26 (positional dcp_size tails on the
  attention / MLA / DSA ops). Stale-payload loops reject 20..25; the 25
  payload keeps the selector like the decoupling branch's 21.
- cp_size: upstream added a CP1-only `cp_size` to compile_engine,
  estimate_kv_cache / estimate_num_gpu_blocks, EngineBuildRequest and the
  legacy Rust compile path ("this SDK entry point does not support context
  parallelism"). This branch supports prefill CP at exactly those entry
  points, so the duplicate parameters / struct field are folded into ours,
  the CP1 gates become positive-integer validation, and the FPM profile cell
  selection receives the real cp_size (a profile without that cell fails
  loud with "no matching FPM deployment profile"). Upstream's tests are
  adjusted accordingly.
- FpmCompileConfig / AicTimingConfig parallel-shape checks combine
  upstream's `fpm_profile.is_none()` exemption with the `* cp_size` fold;
  aic_capacity_kwargs gains cp_size / dcp_size; fpm best_available keeps
  upstream's registered-architecture check ahead of the DCP mode gate.
- capacity.py worker resolution carries aic_cp_size / aic_dcp_size next to
  aic_fpm_profile / worker_type.
- ParallelismPresetConfig.prefill_context becomes Optional (None = 1), like
  decode_context, so default parallelism dumps carry no CP keys; the new
  onboarding topology tests (ai-dynamo#248) compare those dumps against the
  six-key request parallelism. Consumers read it through compiler._prefill_cp.

Signed-off-by: Tianhao Xu <tianhaox@nvidia.com>
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
carlory pushed a commit to carlory/aisimulate that referenced this pull request Oct 30, 2026
* feat: add configurable spline FPM regression

Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>

* docs: clarify spline regression contracts and evidence

Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>

* test: cover spline rebuild diagnostics across knot searches

Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>

* fix: gate spline forecasts on shared linear availability

Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>

* fix: make new spline controls extensible

Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>

* docs: report guarded spline production accuracy

Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>

---------

Signed-off-by: Yueqi Zhao <yueqiz@nvidia.com>
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3 participants