How to decrease time it takes to benchmark?

Question

I have the following benchmark that takes a very long time to complete. What measures can I take to improve the time it takes to run the benchmark without losing its effectiveness?

on_initialize {
        let m in 1 .. 3_000;
        for j in 0 .. m {
            let mortality_block = 49 as u32;
            let sig = generate_test_signature();
            assert_ok!(Msa::<T>::register_signature(&sig, T::BlockNumber::from(mortality_block)));
        }

        let bucket_zero_iter = PayloadSignatureRegistry::<T>::iter_prefix(T::BlockNumber::from(0u32));
        assert_eq!(bucket_zero_iter.count(), m as usize);
    }: {
        Msa::<T>::on_initialize(100u32.into());
    } verify {
        let bucket_zero_iter = PayloadSignatureRegistry::<T>::iter_prefix(T::BlockNumber::from(0u32));
        assert_eq!(bucket_zero_iter.count(), 0 as usize);
    }

Running with the following configurations:

• --steps 50
• --repeat 10

Answer 1

I checked your code and the signature generation is very slow.
However, the signatures are never verified so you can get away by mocking them which is million times faster.
First lets increase the 3_000 to 50_000 for a larger effect. Then get rid of the generate_test_signature function and mock the signature.

let m in 1 .. 50_000;
for j in 0 .. m {
    let mut sig = [0u8; 64];
    sig[0..8].copy_from_slice(&(m, j).encode());
    let sig = MultiSignature::Sr25519(sp_core::sr25519::Signature::from_raw(sig));

    let mortality_block = 49 as u32;
    assert_ok!(Msa::<T>::register_signature(&sig, T::BlockNumber::from(mortality_block)));
}

PS: Running the benchmark tests with --release also helps.

Please always include source code links to your questions and an elaborate explanation of the problem, thanks.