Benchmarking programs in Rust

Question

How is it possible to benchmark programs in Rust? For example, how would I get execution time of program in seconds?

Answer 1

For measuring time without adding third-party dependencies, you can use std::time::Instant:

fn main() {     use std::time::Instant;     let now = Instant::now();      // Code block to measure.     {         my_function_to_measure();     }      let elapsed = now.elapsed();     println!("Elapsed: {:.2?}", elapsed); } 

Answer 2

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