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This post is auto-generated from RSS feed The Rust Programming Language Forum - Latest topics. Source: Printing a variable somehow improving performance?

I've been doing some testing and stumbled upon something interesting.

The following function takes around 1600ms to sort a vector of 100 000 elements

fn sort(values: &mut [u32]) {
    let mut swaps: u64 = 0;
    let mut i = 1;
    let len = values.len();
    while i < len {
        let mut j = i;
        while j > 0 && values[j-1] > values[j] {
            swaps += 1;
            values.swap(j, j-1);
            j -= 1
        }
        i += 1
    }
    //println!("{swaps}")
}

But after uncommenting the print statement, the time drops to 1400ms

fn sort(values: &mut [u32]) {
    let mut swaps: u64 = 0;
    let mut i = 1;
    let len = values.len();
    while i < len {
        let mut j = i;
        while j > 0 && values[j-1] > values[j] {
            swaps += 1;
            values.swap(j, j-1);
            j -= 1
        }
        i += 1
    }
    println!("{swaps}")
}

any thoughts on what could be causing this discrepancy?

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