benchmarks2.md

More Complicated Benchmarks

Recommended crate:

• Criterion

Setting Up Criterion

In Cargo.toml, add:

[dev-dependencies]
criterion = { version = "0.4", features = [ "html_reports" ] }

[[bench]]
name = "my_benchmark"
harness = false

[dev-dependencies] is new! This is a dependency that is only loaded by development tools, and isn't integrated into your final program. No space is wasted.

Create benchmark2/benches/my_benchmark.rs:

use criterion::{black_box, criterion_group, criterion_main, Criterion};

fn fibonacci(n: u64) -> u64 {
    match n {
        0 => 1,
        1 => 1,
        n => fibonacci(n-1) + fibonacci(n-2),
    }
}

fn criterion_benchmark(c: &mut Criterion) {
    c.bench_function("fib 20", |b| b.iter(|| fibonacci(black_box(20))));
}

criterion_group!(benches, criterion_benchmark);
criterion_main!(benches);

Taken from the Criterion demo page. The "Optimizing & Debugging Rust" class goes into a lot more detail.

Run cargo bench and see the result.

Go to target/criterion and you have a full HTML report with statistics.