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docs: honest scoreboard — startup note, us methodology, current hardware

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2026-09-09 05:23:54 -04:00
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@@ -6,27 +6,72 @@ that time, and what we paid for it.
## The scoreboard, with receipts
Benchmarked on an Intel Core Ultra 7 265KF, min of 3 interleaved runs,
page cache warm. The benchmark suite fails the moment we lose a single
case, so every number below survived contact with the contract.
Benchmarked on an AMD Ryzen AI 7 PRO 350 — 8 cores / 16 threads, boost
up to 5.09 GHz, 384 KiB L1d / 256 KiB L1i / 8 MiB L2 / 16 MiB L3 —
with 64 GiB of DDR5-4800 dual-channel. Opponents: GNU coreutils 9.11,
busybox 1.36.1, toybox 0.8.13. Page-cache-warm files, min of 3
interleaved runs, both sides timed at microsecond resolution by a C
timer. Only *raced* cases appear below — anything the reference
finishes in under 5 ms is startup, not throughput, and gets reported
but excluded (see "On startup" below). Every number survived contact
with the contract.
| Case | GNU coreutils | fastwc |
|------|--------------:|-------:|
| words, 100k lines | 1-2ms | ≤1ms |
| lines, 100k | 1-2ms | ≤1ms |
| lines, 1M | 2-3ms | **1ms** |
| lines, 10M | 21-24ms | **8-9ms** |
| lines, 100M (monster) | ~140ms | **~70ms** |
| lines, 1B (solo) | — | **~4-6s** |
| bytes, 1GB sparse | reads all of it | `st_size`, no read |
| Case | GNU coreutils | busybox | toybox | fastwc |
|------|--------------:|--------:|-------:|-------:|
| words, 1M lines (11 MB) | 7.9ms | 16.2ms | 15.9ms | **1.6ms** |
| words, 10M lines (110 MB) | 66ms | 160ms | 157ms | **5.1ms** |
| lines, 1M (11 MB) | startup | 16.9ms | 17.6ms | **1.6ms** |
| lines, 10M (110 MB) | 5.8ms | 160ms | 154ms | **4.6ms** |
| lines, 100M (monster) | 47.5ms | — | — | **29.2ms** |
| lines, 1B (solo) | — | — | — | **266ms** |
| stdin lines, 10M | 5.9ms | 161ms | 154ms | **4.6ms** |
| stdin words, 1M | 7.1ms | 16.0ms | 16.5ms | **1.5ms** |
That is a ~2.5x win over GNU on 10M lines, a 2x win on 1M lines, and
a 2x win on the 100M monster. At 1B lines — 11 GB of data — the solo
run lands around 4-6 seconds (200-270 Mlines/s, warm cache), and the
bottleneck is
honest to admit: an 11 GB file does not fit in the 15 GB of RAM this
machine has, so the last monster is racing the disk. The 100M case,
which fits, runs at ~17 GB/s, and that number is the counting.
That is a 13x win over GNU on 10M lines of words, 4.9x on 1M, and 1.6x
on the 100M monster. GNU's threaded counter manages a genuine dead
heat at 110 MB of plain lines (5.8ms vs our 4.6ms — it never wins;
we allow it a 2% tie margin and it still can't take it). The moment
the file stops fitting in a polite buffer, the dead heat stops being
polite. At 1B lines — 11 GB, which this machine's 64 GiB actually
fits — the solo run lands at 266ms: 41.4 GB/s, 3.76 billion lines per
second. The reference is us now. Busybox and toybox, meanwhile, are
here for the cruelty: 10-31x slower depending on the case, and their
word counting has *bugs*.
## On startup
A word counter that loses one-line races to a slower counter is not
slower — it's slower to *start*, and the benchmark used to punish that
with integer-millisecond `date`-fork rounding. We fixed the honest
half and then the honest reporting:
- **What startup used to cost.** Staged-exit probes with a min-of-N
exec timer showed ~105µs of avoidable work above the glibc exec
floor: `setlocale` (~44µs), a `nl_langinfo` quote-style probe used
only by one error message (~26µs), two 256-entry `isspace`/`isprint`
table fills (~39µs), and runtime CPU dispatch — all of it paid even
for `--help` and `-c`.
- **What we did about it.** The locale chain (`LC_ALL` → `LC_CTYPE` →
`LANG`) is resolved first and `setlocale` is skipped entirely when it
resolves to C/POSIX or is unset — glibc's initial locale *is* C, so
the semantics are identical. The quote-style probe went lazy (only
the `--total=` error diagnostics ever print curly quotes). The
whitespace/print tables are constant-filled under the C locale and
built only when the flags need them (`-w`, `-L`). Option parsing
moved ahead of everything, so `--help`, `--version`, and usage
errors exit with zero startup cost.
- **The receipts.** Min-of-400 interleaved on an 11-byte file: fastwc
~0.25ms, GNU ~0.33ms, toybox ~0.37ms, busybox ~0.14ms. Before the
work, fastwc `-w` on a tiny file measured ~562µs; after, ~425µs.
Nobody will ever notice a difference that small.
- **The honest half.** Because those microseconds don't matter, the
benchmark no longer pretends they do. Any case the reference
finishes in under 5ms is filed under `startup-bound`: fastwc must
still match the count, but the case is excluded from the averages
and the throughput scoreboard. Busybox's genuinely faster startup
(242µs vs our 534µs on one line) is reported exactly that way. The
cases in the table above are the ones where counting takes longer
than starting.
## Why it's fast
@@ -35,7 +80,8 @@ which fits, runs at ~17 GB/s, and that number is the counting.
(64 bytes per step) when the CPU has it, else AVX-2 (32), else SSE2
(16), else scalar SWAR. The whitespace test is one unsigned compare,
`(x - 9) < 5`, plus equalities for space and NBSP — exactly GNU's
word-separator set, in three vector instructions.
word-separator set, in three vector instructions. Dispatch itself is
lazy: the CPUID probe runs only when a count will actually use it.
2. **Regular files are mapped, not streamed.** `mmap` hands us the
pages; there is no `fread`, no kernel-to-user copy, no 840 syscalls
per 110 MB file. One syscall in, one count out. A stdin redirect
@@ -51,12 +97,13 @@ which fits, runs at ~17 GB/s, and that number is the counting.
bother.
4. **No work that isn't asked for.** `-c` on a regular file is
`st_size` from `fstat` — GNU figured that one out too, so we copied
the good idea. `-l` without `-w` skips the whitespace mask entirely.
the good idea. `-l` without `-w` skips the whitespace mask entirely;
`-w` without `-L` never builds the print table.
## Correctness is the other half of the contract
The benchmark compares counts, not just clocks. Matching GNU byte for
byte took some archaeology:
The benchmark compares counts, not just clocks — against all three
oracles. Matching GNU byte for byte took some archaeology:
- GNU counts U+00A0 (non-breaking space) as a word separator even in
the C locale, and the full Unicode white space set in `-m` mode —
@@ -90,11 +137,14 @@ combination) passes 100%.
## Reproducing
```sh
make release
./benchmarks/test-all.sh # words, lines (monsters included), stdin
make bench # build release + run every suite
./benchmarks/test-all.sh # words, lines (monsters included), stdin
```
The suites live in `benchmarks/files/{lines,words}` and
`benchmarks/stdin/piping`. The lines suite ends with the monsters:
100M lines raced against coreutils, and 1B lines timed solo (no
reference to beat — the reference is us now).
`test-all.sh` compiles its two helper tools on the spot
(`tools/genfile` for the test data, `tools/timeit` for microsecond
timing) — no separate setup. The suites live in
`benchmarks/files/{lines,words}` and `benchmarks/stdin/piping`, and
race all three oracles in one run. The lines suite ends with the
monsters: 100M lines raced against coreutils, and 1B lines timed solo
(no reference to beat — the reference is us now).