bench loops

bench.rs

#![feature(test)]

extern crate test;

use test::Bencher;

#[bench]
fn for_range_100(b: &mut Bencher) { b.iter(|| { test::black_box(for _ in 0..100 {}); }); }

#[bench]
fn for_range_1000(b: &mut Bencher) { b.iter(|| { test::black_box(for _ in 0..1000 {}); }); }

#[bench]
fn for_range_10000(b: &mut Bencher) { b.iter(|| { test::black_box(for _ in 0..10000 {}); }); }

#[bench]
fn for_while_100(b: &mut Bencher) { 
    b.iter(|| { 
        let mut i = 0; 
        while i < test::black_box(100) { i+=1; }
    });
}

#[bench]
fn for_while_1000(b: &mut Bencher) {
    b.iter(|| {
        let mut i = 0;
        while i < test::black_box(1000) { i+=1; }
    });     
}       
    
#[bench]
fn for_while_10000(b: &mut Bencher) {
    b.iter(|| {
        let mut i = 0;
        while i < test::black_box(10000) { i+=1; }
    });     
} 

result

$ rustc bench.rs -O --test && ./bench --bench

running 6 tests
test for_range_100   ... bench:        89 ns/iter (+/- 2)
test for_range_1000  ... bench:       929 ns/iter (+/- 98)
test for_range_10000 ... bench:      8815 ns/iter (+/- 414)
test for_while_100   ... bench:        36 ns/iter (+/- 3)
test for_while_1000  ... bench:       294 ns/iter (+/- 27)
test for_while_10000 ... bench:      2768 ns/iter (+/- 268)

test result: ok. 0 passed; 0 failed; 0 ignored; 6 measured

$ rustc --version
rustc 1.1.0-nightly (e5394240a 2015-05-14) (built 2015-05-14

$ uname -a
Linux debian 3.2.0-4-amd64 #1 SMP Debian 3.2.68-1+deb7u1 x86_64 GNU/Linux