Oh, I see, then I think it's not mock or koji's fault, cuz I use x86_64 host
machine to emulate aarch64 by qemu as the builder. So, I think it's because of QEMU.
Do you have any idea how "koji.fedora.org" build different architecture's
rpm in such a short time? How they set up their "Kojibuilder"? By using specific
CPU hardware straightly or emulating CPU by QEMU from X86_64?