1e7 testing
     vr_pdl3:    46.328s  cache
     vr_pdl2:  1m16.058s  non-cache
    mce_pdl2:  1m15.583s  chunk_size => $size
    mce_pdl2:  1m03.709s  chunk_size => $size >> 1
    mce_pdl2:    52.352s  chunk_size => $size >> 2
    mce_pdl2:    51.323s  chunk_size => $size >> 3
    mce_pdl2:    49.396s  chunk_size => $size >> 4
    mce_pdl2:    48.195s  chunk_size => $size >> 5
    mce_pdl2:    48.369s  chunk_size => $size >> 6
    mce_pdl2:    48.501s  chunk_size => $size >> 7

chunk_size => 300000
    mce_pdl2:    48.195s   1 core
    mce_pdl2:    25.311s   2 cores
    mce_pdl2:    14.085s   4 cores
    mce_pdl2:     7.650s   8 cores
    mce_pdl2:     4.517s  16 cores
    mce_pdl2:     3.721s  32 cores

chunk_size => 100000
    mce_pdl2:    48.395s   1 core
    mce_pdl2:    25.402s   2 cores
    mce_pdl2:    13.163s   4 cores
    mce_pdl2:     6.860s   8 cores
    mce_pdl2:     3.850s  16 cores
    mce_pdl2:     2.347s  32 cores

Output
    Collatz(8400511) has sequence length of 686 steps
    Collatz(8865705) has sequence length of 668 steps
    Collatz(6649279) has sequence length of 665 steps
    Collatz(9973919) has sequence length of 663 steps
    Collatz(6674175) has sequence length of 621 steps
    Collatz(7332399) has sequence length of 616 steps
    Collatz(7532665) has sequence length of 616 steps
    Collatz(5649499) has sequence length of 613 steps
    Collatz(8474249) has sequence length of 611 steps
    Collatz(6355687) has sequence length of 608 steps
    Collatz(8847225) has sequence length of 606 steps
    Collatz(9533531) has sequence length of 606 steps
    Collatz(6635419) has sequence length of 603 steps
    Collatz(9953129) has sequence length of 601 steps
    Collatz(7464846) has sequence length of 598 steps
    Collatz(7464847) has sequence length of 598 steps
    Collatz(3732423) has sequence length of 597 steps
    Collatz(5598635) has sequence length of 595 steps
    Collatz(8397953) has sequence length of 593 steps
    Collatz(6298465) has sequence length of 590 steps