Source code
Revision control
Copy as Markdown
Other Tools
//! Benchmarks that compare TinyVec to SmallVec↩
//!↩
//! All the following commentary is based on the latest nightly at the time:↩
//! rustc 1.55.0 (c8dfcfe04 2021-09-06).↩
//!↩
//! Some of these benchmarks are just a few instructions, so we put our own for↩
//! loop inside the criterion::Bencher::iter call. This seems to improve the↩
//! stability of measurements, and it has the wonderful side effect of making↩
//! the emitted assembly easier to follow. Some of these benchmarks are totally↩
//! inlined so that there are no calls at all in the hot path, so finding↩
//! this for loop is an easy way to find your way around the emitted assembly.↩
//!↩
//! The clear method is cheaper to call for arrays of elements without a Drop↩
//! impl, so wherever possible we reuse a single object in the benchmark loop,↩
//! with a clear + black_box on each iteration in an attempt to not make that↩
//! visible to the optimizer.↩
//!↩
//! We always call black_box(&v), instead of v = black_box(v) because the latter↩
//! does a move of the inline array, which is linear in the size of the array↩
//! and thus varies based on the array type being benchmarked, and this move can↩
//! be more expensive than the function we're trying to benchmark.↩
//!↩
//! We also black_box the input to each method call. This has a significant↩
//! effect on the assembly emitted, for example if we do not black_box the range↩
//! we iterate over in the ::push benchmarks, the loop is unrolled. It's not↩
//! entirely clear if it's better to black_box the iterator that yields the↩
//! items being pushed, or to black_box at a deeper level: v.push(black_box(i))↩
//! for example. Anecdotally, it seems like the latter approach produces↩
//! unreasonably bad assembly.↩
↩
use criterion::{black_box, criterion_group, criterion_main, Criterion};↩
use smallvec::SmallVec;↩
use std::iter::FromIterator;↩
use tinyvec::TinyVec;↩
↩
const ITERS: usize = 10_000;↩
↩
macro_rules! tinyvec_benches {↩
($c:expr, $type:ty ; $len:expr) => {{↩
let mut g = $c.benchmark_group(concat!(↩
"TinyVec_",↩
stringify!($type),↩
"_",↩
stringify!($len)↩
));↩
↩
g.bench_function(↩
concat!(↩
"TinyVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::default"↩
),↩
|b| {↩
b.iter(|| {↩
for _ in 0..ITERS {↩
let v: TinyVec<[$type; $len]> = TinyVec::default();↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"TinyVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::clone"↩
),↩
|b| {↩
b.iter(|| {↩
let outer: TinyVec<[$type; $len]> =↩
black_box(TinyVec::from_iter(0..=($len as usize - 1) as _));↩
for _ in 0..ITERS {↩
let v = outer.clone();↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"TinyVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::clear"↩
),↩
|b| {↩
b.iter(|| {↩
let mut v: TinyVec<[$type; $len]> = TinyVec::default();↩
for _ in 0..ITERS {↩
v.clear();↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"TinyVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::push"↩
),↩
|b| {↩
b.iter(|| {↩
let mut v: TinyVec<[$type; $len]> = TinyVec::default();↩
for _ in 0..ITERS {↩
v.clear();↩
black_box(&v);↩
for i in black_box(0..=($len as usize - 1) as _) {↩
v.push(i);↩
}↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"TinyVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::from_iter"↩
),↩
|b| {↩
b.iter(|| {↩
for _ in 0..ITERS {↩
let v: TinyVec<[$type; $len]> =↩
TinyVec::from_iter(black_box(0..=($len as usize - 1) as _));↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"TinyVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::from_slice"↩
),↩
|b| {↩
b.iter(|| {↩
let data: &[$type] = &[0, 1, 2, 3, 4, 5, 6, 7];↩
for _ in 0..ITERS {↩
let v: TinyVec<[$type; $len]> = TinyVec::from(black_box(data));↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"TinyVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::extend"↩
),↩
|b| {↩
b.iter(|| {↩
let mut v: TinyVec<[$type; $len]> = black_box(TinyVec::default());↩
for _ in 0..ITERS {↩
v.clear();↩
black_box(&v);↩
v.extend(black_box(0..=($len as usize - 1) as _));↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"TinyVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::extend_from_slice"↩
),↩
|b| {↩
b.iter(|| {↩
let data: &[$type] = black_box(&[0, 1, 2, 3, 4, 5, 6, 7]);↩
let mut v: TinyVec<[$type; $len]> = black_box(TinyVec::default());↩
for _ in 0..ITERS {↩
v.clear();↩
black_box(&v);↩
v.extend_from_slice(data);↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"TinyVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::insert"↩
),↩
|b| {↩
b.iter(|| {↩
let mut v: TinyVec<[$type; $len]> = TinyVec::default();↩
for _ in 0..ITERS {↩
v.clear();↩
black_box(&v);↩
for i in black_box(0..=($len as usize - 1) as _) {↩
v.insert(i as usize, i);↩
}↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"TinyVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::remove"↩
),↩
|b| {↩
b.iter(|| {↩
let outer: TinyVec<[$type; $len]> =↩
black_box(TinyVec::from_iter(0..=($len as usize - 1) as _));↩
for _ in 0..ITERS {↩
let mut v = outer.clone();↩
for i in black_box((0..=($len as usize - 1) as _).rev()) {↩
v.remove(i);↩
}↩
black_box(&v);↩
}↩
});↩
},↩
);↩
}};↩
}↩
↩
fn tinyvec_benches(c: &mut Criterion) {↩
tinyvec_benches!(c, u8; 8);↩
tinyvec_benches!(c, u8; 16);↩
tinyvec_benches!(c, u8; 32);↩
tinyvec_benches!(c, u8; 64);↩
tinyvec_benches!(c, u8; 128);↩
tinyvec_benches!(c, u8; 256);↩
tinyvec_benches!(c, u64; 2);↩
tinyvec_benches!(c, u64; 4);↩
tinyvec_benches!(c, u64; 8);↩
tinyvec_benches!(c, u64; 16);↩
tinyvec_benches!(c, u64; 32);↩
}↩
↩
macro_rules! smallvec_benches {↩
($c:expr, $type:ty ; $len:expr) => {{↩
let mut g = $c.benchmark_group(concat!(↩
"SmallVec_",↩
stringify!($type),↩
"_",↩
stringify!($len)↩
));↩
↩
g.bench_function(↩
concat!(↩
"SmallVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::default"↩
),↩
|b| {↩
b.iter(|| {↩
for _ in 0..ITERS {↩
let v: SmallVec<[$type; $len]> = SmallVec::default();↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"SmallVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::clone"↩
),↩
|b| {↩
b.iter(|| {↩
let outer: SmallVec<[$type; $len]> =↩
black_box(SmallVec::from_iter(0..=($len as usize - 1) as _));↩
for _ in 0..ITERS {↩
let v = outer.clone();↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"SmallVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::clear"↩
),↩
|b| {↩
b.iter(|| {↩
let mut v: SmallVec<[$type; $len]> = SmallVec::default();↩
for _ in 0..ITERS {↩
v.clear();↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"SmallVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::push"↩
),↩
|b| {↩
b.iter(|| {↩
let mut v: SmallVec<[$type; $len]> = SmallVec::default();↩
for _ in 0..ITERS {↩
v.clear();↩
black_box(&v);↩
for i in black_box(0..=($len as usize - 1) as _) {↩
v.push(i);↩
}↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"SmallVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::from_iter"↩
),↩
|b| {↩
b.iter(|| {↩
for _ in 0..ITERS {↩
let v: SmallVec<[$type; $len]> =↩
SmallVec::from_iter(black_box(0..=($len as usize - 1) as _));↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"SmallVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::from_slice"↩
),↩
|b| {↩
b.iter(|| {↩
let data: &[$type] = &[0, 1, 2, 3, 4, 5, 6, 7];↩
for _ in 0..ITERS {↩
let v: SmallVec<[$type; $len]> = SmallVec::from(black_box(data));↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"SmallVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::extend"↩
),↩
|b| {↩
b.iter(|| {↩
let mut v: SmallVec<[$type; $len]> = black_box(SmallVec::default());↩
for _ in 0..ITERS {↩
v.clear();↩
black_box(&v);↩
v.extend(black_box(0..=($len as usize - 1) as _));↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"SmallVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::extend_from_slice"↩
),↩
|b| {↩
b.iter(|| {↩
let data: &[$type] = black_box(&[0, 1, 2, 3, 4, 5, 6, 7]);↩
let mut v: SmallVec<[$type; $len]> = black_box(SmallVec::default());↩
for _ in 0..ITERS {↩
v.clear();↩
black_box(&v);↩
v.extend_from_slice(data);↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"SmallVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::insert"↩
),↩
|b| {↩
b.iter(|| {↩
let mut v: SmallVec<[$type; $len]> = SmallVec::default();↩
for _ in 0..ITERS {↩
v.clear();↩
black_box(&v);↩
for i in black_box(0..=($len as usize - 1) as _) {↩
v.insert(i as usize, i);↩
}↩
black_box(&v);↩
}↩
});↩
},↩
);↩
↩
g.bench_function(↩
concat!(↩
"SmallVec<[",↩
stringify!($type),↩
"; ",↩
stringify!($len),↩
"]>::remove"↩
),↩
|b| {↩
b.iter(|| {↩
let outer: SmallVec<[$type; $len]> =↩
black_box(SmallVec::from_iter(0..=($len as usize - 1) as _));↩
for _ in 0..ITERS {↩
let mut v = outer.clone();↩
for i in black_box((0..=($len as usize - 1) as _).rev()) {↩
v.remove(i);↩
}↩
black_box(&v);↩
}↩
});↩
},↩
);↩
}};↩
}↩
↩
fn smallvec_benches(c: &mut Criterion) {↩
smallvec_benches!(c, u8; 8);↩
smallvec_benches!(c, u8; 16);↩
smallvec_benches!(c, u8; 32);↩
smallvec_benches!(c, u8; 64);↩
smallvec_benches!(c, u8; 128);↩
smallvec_benches!(c, u8; 256);↩
smallvec_benches!(c, u64; 2);↩
smallvec_benches!(c, u64; 4);↩
smallvec_benches!(c, u64; 8);↩
smallvec_benches!(c, u64; 16);↩
smallvec_benches!(c, u64; 32);↩
}↩
↩
criterion_group!(benches, tinyvec_benches, smallvec_benches);↩
criterion_main!(benches);↩