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docs(kernel): §7a.3 batch-loop profile round — countGuard quadratic eliminated, envelope 19.3min; two theories falsified by measurement (#1340)

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Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
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Colby Mchenry
2026-07-17 11:47:40 -05:00
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co-authored by Claude Fable 5
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@@ -657,6 +657,27 @@ synthesis — parallelize/window WITHIN the pass), (c) the R7a C/C++ port
wall — parallelizing WITHIN that one pass (or windowing its scan) is worth more wall — parallelizing WITHIN that one pass (or windowing its scan) is worth more
than pooling all 36 passes. Filed under the next P1 profiling round. than pooling all 36 passes. Filed under the next P1 profiling round.
#### 7a.3 Batch-loop profile + de-quadratic round (2026-07-17, #1339)
`CODEGRAPH_RESOLVE_PROFILE` (shipped in #1339: per-outcome resolveOne histogram
+ loop-stage attribution) overturned the arc's founding assumption — resolveOne
owns only **~93s** of the ~433s kernel-scale batch loop. Stage attribution and
what happened to each:
| Stage | Before | After #1339 | Note |
|---|---|---|---|
| countGuard | 93.9s | **0.0s** | per-batch COUNT(*) was O(remaining) — replaced by summed SQLite `changes` (zero-removals IS the runaway signal; real COUNT only arbitrates the suspicious path) |
| read | 54.6s | 57.2s | keyset replaced OFFSET, but the cost is row MAPPING (5000-row materialization + candidates JSON), not prefix-walking — theory falsified, keyset kept as hygiene; lever = leaner row mapping |
| backpressure | 111.2s | 121.2s | DB-scaled caps didn't help: the fold tax is TOTAL checkpoint I/O (write set is cold pages, not re-dirtied hot ones) — a disk-I/O floor ≈ WAL bytes written |
| settle (resolveOne) | 85.7s | 88.0s | the real work; exact-match 3.17M×13µs=41s is the biggest legit class |
| inserts/deletes/marks | ~84s | ~84s | B-tree floor (#1320 post-mortem) |
**2c/6GB envelope: 26.4min (R6) → 20.4 (#1336) → 19.3min (#1339), counts
byte-exact every run; dubbo dump byte-identical.** The 8-core re-run post-#1339
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.
### 7b. Arc 3 — graph richness (forensics-backed; adopt cbm's real extras, skip inflation) ### 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: 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 1. **Test→subject edges** (first-class `tests` edges at index time; we compute covering