shoney.arickathil
a873cf7331
- `randread N R` in the sample: fill N rows, read R across the WHOLE range - Weyl order `i*2654435761 mod n` — no RNG in the language, none needed; both legs read the SAME key order so residency is the only variable - `randread` driver leg: control (256 MiB, does not bind) vs over-cap (6 MiB + swap), sizes kept modest — quick resolves it in ~5s - gates the RATIO, not the absolutes: over-cap reads/sec belongs to the box's swap device, the factor between two runs belongs to the engine - reads must all resolve (hits == R) or the leg fails; a collapse measured over unresolved reads is noise - 133 checks, 0 failures; gate bites on a doctored collapse_x Measured — this closes the gap the swap leg left: - resident 1 851 166 reads/sec, p50 0us p99 1us - over-cap 6 771 reads/sec, p50 128us p99 487us - 273x throughput, ~480x p99, all 20 000 reads resolving in both - so the two access patterns sit ~270x apart under identical pressure: append-mostly insert ~1%, random read 273x - departure is a STEP not a curve (1us -> 487us, nothing between), which is why p99_departure_decile finds no knee — there is none - caveat recorded, NOT inherited: this is demand-paged anonymous memory through swap (4 KiB/fault, no readahead). `resident: keys` preads via the page cache — should be better, but databasev2 2 task 7 must measure its own read path. New criterion added there Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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|---|---|---|
| .. | ||
| main.wo | ||
| README.md | ||
| types.wo | ||
| wo.toml | ||
db-bench — iteration 22's load generator
The measurement backbone (spec:
docs/superpowers/specs/2026-08-21-db-bench-design.md). Pure .wo;
every measured mode prints one machine-parsable line per operation
class:
<op> <count> <ops/sec> <p50us> <p99us>
Timing is per-operation via time.ticks (CLOCK_MONOTONIC µs).
Percentiles come from a 1µs-bucket histogram clamped at 20000µs — exact
to the microsecond below the clamp; a p99 AT 20000 means "clamp or
worse". (A histogram, not the spec's reservoir: the language has no
container element-write or sort, and the histogram's tail fidelity is
strictly better. Recorded as a plan deviation.)
Modes
| mode | what it prices |
|---|---|
all N |
the throughput campaign in ONE process: seed N, read N/2, query N/10, write N/2. Without WO_DATA the store is RAM and dies with the process, so the measured modes must share the seeding run. |
seed N |
timed inserts: one parent per 100 children (FK probe each insert, unique-index maintenance per parent), k non-unique (10 rows/key), deterministic v. Writes Meta expectation rows. |
read N |
indexed take-1 point lookups, LCG-spread keys. |
query N |
full equality probes on the k index (≈10 rows each), materialized and counted. |
write N |
alternating inserts (disjoint k range 2e6+) and updates through query results. Corrupts the checksum by design — durability legs run on a fresh store. |
wal N |
the crash battery's vehicle: insert-only (k range 1e6+), acked <i> printed AFTER each insert returns — the return IS the ack (RAM applied, WAL record staged, ONE commit done). |
verify |
store vs its own Meta rows: count, checksum, one unique probe. Exit 3 on mismatch. |
verify-acked M |
after kill -9 mid-wal: rows 1..M exist with the right v; rows beyond M allowed (acked after the last print flushed). Exit 3 on mismatch. |
Coordination idiom (this side of iteration 31)
There is no request/response surface yet: concurrent modes drive completion the db-actor way — actors write rows, main polls the store until the expected count, then settles. Retired when 31 lands.
Standing finding (2026-08-21, first run)
A hand-built multi Bucket of insert results SEGVs on drop: the
compiler classifies the elements OWNED while table refs are scalar ids.
Query-built multis are runtime-typed and safe. Worked around here
(single ref local, bucket-major seeding); the compiler fix is its own
slice.
Reference-machine numbers (first campaign, 2026-08-21)
bench/baseline.json is the contract; headline readings:
- ram seed 245–290k inserts/s; durable seed ≈4.5k/s (fsync-per-commit ≈220µs each — the gap iteration 23 exists to close).
- reads/queries ≈1.1–1.3M ops/s at p50 1µs since the read-path index
slice (2026-08-22, engine
wo_idx_probe+ emitter index selection) — up from ≈1.5k/s at p50 600µs when point lookups walked every slab (~×850). mixread 89k ops/s single-shard, ~1.9k multi-shard (was 1,280 / 21): the RPC round-trip is now the visible cost, as designed. - msgrate ≈13M msgs/s same-heap vs ≈2.4M cross-shard (the mutex-inbox number, stage-2 deviation 4).
- Tolerance policy lives in the DRIVER (
tolerance_for), not hand-edits — a baseline refresh regenerates it: mix*/sN/read/query 50% (scheduling + µs-scale jitter), rest 15%; latency floorsmax(4×value, 100µs)— the tripwire means "µs became ms".
The gate must bite (proven 2026-08-21)
scripts/db-bench.py --check <results.json> evaluates a recorded run:
the real results pass 74/0; a doctored copy FAILS on exactly the
doctored metrics — use a 15%-class metric (seed) halved plus a
50%-class metric (read) quartered, so both tolerance classes prove they
bite. Re-run the smoke after any gate or policy change.