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docs: ObjectHeader::parse A/B rechecked on an idle machine

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+6-7% (about 4 ns per header) is real; symbol-table nodes -17%, group
B-tree walk -16%, facade listing -2.4%: local metadata reads are net
slightly faster than main.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
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osobh
2026-09-26 15:15:32 -05:00
co-authored by Claude Opus 5.5
parent b49ec39aff
commit cadd27df5b
1 changed files with 9 additions and 2 deletions
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Criterion bench itself, old and new as separate binaries run alternately Criterion bench itself, old and new as separate binaries run alternately
(3 rounds), agrees except for `ObjectHeader::parse`, which it puts about (3 rounds), agrees except for `ObjectHeader::parse`, which it puts about
7% slower (25.9 vs 24.1 µs for 401 headers) while the listing that 7% slower (25.9 vs 24.1 µs for 401 headers) while the listing that
parses those headers is 5–8% faster; that one remains unexplained and is parses those headers is 5–8% faster. **Rechecked on an idle tank
to be rechecked on an idle machine. (2026-09-26, load 1.95 at the start, 3–4 during; Criterion, `main`
`479d8b4` vs this branch `b49ec39` as separate binaries, 2 alternating
rounds):** `ObjectHeader::parse` for 401 headers 24.0–24.1 µs → 25.5–25.8
µs (+6–7%, about 4 ns per header — real, not noise); symbol-table nodes
2.39 → 1.94–2.04 µs (−17%); group B-tree walk 405–411 → 322–351 ns
(−16%); listing the 400-group file through the facade 8.56–8.71 →
8.40–8.42 ms (−2.4%). Net, local metadata reads are slightly faster; the
per-header cost is a known, small regression.
- New equivalence harness `clawhdf5-format/tests/storage_equivalence.rs`: - New equivalence harness `clawhdf5-format/tests/storage_equivalence.rs`:
every converted parser runs over the file as a slice and over every converted parser runs over the file as a slice and over
`storage::CountingStorage` — a `Storage` that serves an in-memory buffer `storage::CountingStorage` — a `Storage` that serves an in-memory buffer