# Benchmarking With Inputs
Criterion.rs can run benchmarks with multiple different input values to investigate how the performance behavior changes with different inputs.
```rust
static KB: usize = 1024;
Criterion::default()
.bench_function_over_inputs("from_elem", |b, &&size| {
b.iter(|| iter::repeat(0u8).take(size).collect::<Vec<_>>());
}, &[KB, 2 * KB, 4 * KB, 8 * KB, 16 * KB])
```
In this example, we're benchmarking the time it takes to collect a iterator producing a sequence of N bytes into a Vec. We use the `bench_function_over_inputs` method. Unlike `bench_function`, the lambda here takes a Bencher and a reference to a parameter, in this case `size`. Finally, we provide a slice of potential input values. This generates five benchmarks, named "from_elem/1024" through "from_elem/16384" which individually behave the same as any other benchmark. Criterion.rs also generates some charts in `target/criterion/from_elem/report/` showing how the iteration time changes as a function of the input.
Here we can see that there is a approximately-linear relationship between the length of an iterator and the time taken to collect it into a Vec.
