This is required to be set and be equal to write size on FreeBSD.
    Note that despite documentation says it should be in host order,
    it only works if specified in network order

commit b551ed495bcc508e614fd14a25912301b1122a17
Author: Dmitry Marakasov <amdmi3@amdmi3.ru>
Date:   Fri Oct 7 17:32:44 2016 +0300