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docs(kernel): §7a.4 cFnPtr round record — 2.07x standalone, 17.6min envelope, LRU-cyclic-thrash lesson (#1342)

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Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
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Colby Mchenry
2026-07-17 12:40:03 -05:00
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co-authored by Claude Fable 5
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@@ -678,6 +678,37 @@ is pending (est. ~17.5min from the stage arithmetic). Remaining levers by size:
parse 351s→R7a C/C++ port; cFnPtrEdges 306s; backpressure 121s (I/O floor —
shrinks only by writing fewer bytes); settle 88s; read-mapping 57s.
#### 7a.4 cFnPtrEdges round (2026-07-17, #1341) — 2.07× standalone, probe-driven
Iterated with a STANDALONE in-container probe against the live kernel DB
(readonly; ~4min/cycle instead of 25-min inits) with per-sweep sub-timings
(`CODEGRAPH_SYNTH_TIMINGS` prints the `cFnPtr sub:` line):
| Iteration | Standalone total | What moved |
|---|---|---|
| baseline | 278.8s | attribution: E 112s, D 92s, strip 71.8s (4.4×/file), C 41s |
| regex hoists + D field-name pre-gate + incremental line count | 249.3s | D −24s |
| budget-aware strip cache (first cut) | — | **thrash lesson: a partial LRU on cyclic sweeps ≈ 0% cross-sweep hits** — cap ~61k AND cap == files.length both lost (includes push the working set over) |
| all-or-nothing cache + 5% slack | 187.8s | strips exactly 1.0/file; `getNodesInFile` theory killed (10s, not 127s) |
| `sliceLines` → split-once-per-file | **134.8s** | ~1.6M full-file splits eliminated (D 46→20.5s, E 94.5→69.1s) |
**Identity proof at full scale:** optimized edge set (merge-dedup + canonical
sort, 274,762 edges) SHA256 `21c2a971…` == the pre-optimization edges
extracted from the live kernel DB — this pass never runs on the dubbo gate
repo (C-gated), so the DB comparison is the right gate. Suite 2,491.
**In-run validation (2c/6GB): total 17.6min (from 19.3; −33% cumulative vs
R6), synthesis 336→251s, counts byte-exact, WAL 1.09GB.** Honest caveat: the
full strip cache did NOT engage in-run at 6GB (mid-run memory budget below
the 2×-cache safety threshold → deliberate fallback to the 128 floor; strips
283k, costing ~60s vs the probe) — the memory-safe degradation working as
designed. Boxes with headroom get the full 2.07×; the 6GB envelope gets the
algorithmic wins only.
**Levers remaining, re-ranked:** parse 338s (R7a C/C++ port — the last big
rock) > backpressure ~120s (checkpoint I/O floor) > E-scan 69–93s (approaching
honest regex work over 1.5GB) > settle 88s > read-mapping 57s.
### 7b. Arc 3 — graph richness (forensics-backed; adopt cbm's real extras, skip inflation)
Priority order, each gated by the standard A/B + node-explosion probes:
1. **Test→subject edges** (first-class `tests` edges at index time; we compute covering