Benchmarking programs in Rust

It might be worth noting two years later (to help any future Rust programmers who stumble on this page) that there are now tools to benchmark Rust code as a part of one’s test suite.

(From the guide link below) Using the #[bench] attribute, one can use the standard Rust tooling to benchmark methods in their code.

extern crate test;
use test::Bencher;

#[bench]
fn bench_xor_1000_ints(b: &mut Bencher) {
    b.iter(|| {
        // Use `test::black_box` to prevent compiler optimizations from disregarding
        // Unused values
        test::black_box(range(0u, 1000).fold(0, |old, new| old ^ new));
    });
}

For the command cargo bench this outputs something like:

running 1 test
test bench_xor_1000_ints ... bench:       375 ns/iter (+/- 148)

test result: ok. 0 passed; 0 failed; 0 ignored; 1 measured

Links:

• The Rust Book (section on benchmark tests)
• “The Nightly Book” (section on the test crate)
• test::Bencher docs