Files
trueskill-tt/benches/history_converge.rs
T
logaritmiskandClaude Opus 5 b553c630f5 refactor!: K comes first in History, HistoryBuilder and Joint
`K` is the one type parameter people change, and it was last. Naming a
history in a struct field meant writing all four to say one thing:

    struct Ladder { history: History<i64, ConstantDrift, NullObserver, String> }
    struct Analysis<'h> { joint: Joint<'h, i64, ConstantDrift, NullObserver, &'static str> }

Now:

    struct Ladder { history: History<String> }
    struct Analysis<'h> { joint: Joint<'h> }

`History<K, T, D, O>`, all four defaulted. Bounds may reference later
parameters, so `D: Drift<T> = ConstantDrift` is legal in third position.
`Joint` gains the same defaults, so `Joint<'h, String>` spells it.

72 call sites swapped, and the reorder makes most of them shorter: 18
now read `History<String>` and the `&'static str` ones read `History`.
The two turbofished builders shrink from
`HistoryBuilder::<Untimed, _, _, String>::new()` to
`HistoryBuilder::<String, Untimed>::new()`.

`Joint` keeps `O` structurally, defaulted rather than removed. #72 notes
it never touches the observer, which is true — but it borrows the whole
`&'h History<K, T, D, O>` and calls `History::resolve_terms`, so dropping
the parameter means either a view type or moving that method off
`History`. The default already buys the entire user-visible benefit,
which was the spelling.

Refs #72.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-10 06:49:22 +02:00

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//! End-to-end History::converge benchmark.
//!
//! Workload shapes designed to expose rayon's within-slice color-group
//! parallelism. Events in the same color group are processed in parallel
//! via direct-write with disjoint index sets (no data races). Color groups
//! smaller than a threshold fall back to the sequential path to avoid
//! rayon overhead on small workloads.
//!
//! On Apple M5 Pro, the P-core count (6) is the optimal thread count.
//! The rayon thread pool is initialised to `min(P-cores, available)` to
//! avoid scheduling onto the slower E-cores.
//!
//! ## Results (Apple M5 Pro, 2026-04-24, after SmallVec revert)
//!
//! | Workload | Sequential | Parallel | Speedup |
//! |---------------------------------------------|------------:|-----------:|--------:|
//! | History::converge/500x100@10perslice | 4.03 ms | 4.24 ms | 1.0× |
//! | History::converge/2000x200@20perslice | 20.18 ms | 19.82 ms | 1.0× |
//! | History::converge/1v1-5000x50000@5000perslice| 11.88 ms | 9.10 ms | 1.3× |
//!
//! T3 acceptance gate: ≥2× speedup on at least one workload — NOT achieved after revert.
//! The SmallVec storage that enabled the 2× gate caused a +28% regression in the
//! sequential Batch::iteration benchmark and was reverted. Small workloads still fall
//! below the RAYON_THRESHOLD (64 events/color) and run sequentially with near-zero overhead.
use criterion::{BatchSize, Criterion, criterion_group, criterion_main};
use smallvec::smallvec;
use trueskill_tt::{ConstantDrift, ConvergenceOptions, Event, History, Member, Outcome, Team};
fn build_history_1v1(
n_events: usize,
n_competitors: usize,
events_per_slice: usize,
seed: u64,
) -> History<String> {
let mut rng = seed;
let mut next = || {
rng = rng
.wrapping_mul(6364136223846793005)
.wrapping_add(1442695040888963407);
rng
};
let mut h = History::builder()
.key_type::<String>()
.mu(25.0)
.sigma(25.0 / 3.0)
.beta(25.0 / 6.0)
.drift(ConstantDrift::new(25.0 / 300.0))
.convergence(ConvergenceOptions {
max_iter: 30,
epsilon: 1e-6,
alpha: 1.0,
})
.build();
let mut events: Vec<Event<i64, String>> = Vec::with_capacity(n_events);
for ev_i in 0..n_events {
let a = (next() as usize) % n_competitors;
let mut b = (next() as usize) % n_competitors;
while b == a {
b = (next() as usize) % n_competitors;
}
events.push(Event {
time: (ev_i as i64 / events_per_slice as i64) + 1,
teams: smallvec![
Team::with_members([Member::new(format!("p{a}"))]),
Team::with_members([Member::new(format!("p{b}"))]),
],
outcome: Outcome::winner((next() % 2) as u32, 2),
});
}
h.add_events(events).unwrap();
h
}
fn bench_converge(c: &mut Criterion) {
// Two original task workloads (small per-slice event count;
// fall below RAYON_THRESHOLD so sequential path runs — near-zero overhead).
c.bench_function("History::converge/500x100@10perslice", |b| {
b.iter_batched(
|| build_history_1v1(500, 100, 10, 42),
|mut h| {
let _ = h.converge().unwrap();
},
BatchSize::SmallInput,
);
});
c.bench_function("History::converge/2000x200@20perslice", |b| {
b.iter_batched(
|| build_history_1v1(2000, 200, 20, 42),
|mut h| {
let _ = h.converge().unwrap();
},
BatchSize::SmallInput,
);
});
// Large single-slice workload: 5000 events, 50000 competitors.
// All events in one slice → color-0 gets ~4900 disjoint events, well above
// the 64-event RAYON_THRESHOLD. 30 iterations × 1 slice = 30 sweeps, each
// parallelised across P-core threads. Shows ≥2× speedup.
c.bench_function("History::converge/1v1-5000x50000@5000perslice", |b| {
b.iter_batched(
|| build_history_1v1(5000, 50000, 5000, 42),
|mut h| {
let _ = h.converge().unwrap();
},
BatchSize::SmallInput,
);
});
}
criterion_group!(benches, bench_converge);
criterion_main!(benches);