Seeking Advice on Speeding Up Koji Builds with QEMU

I am writing to seek your expertise about using QEMU as a Koji Builder to build packages for the aarch64 on the fedora platform.

When Koji invokes mock for building, it spends a significant amount of time updating yum metadata(≈15mins, <> set as external repo) resulting in taking 30 minutes to init buildroot alone (download speed≈2.8MB/s). I tried to reconfigure “yum_cache” and “root_cache” through both koji and mock but it seems that kojid overrides and False them every time.

I would like to know if there is any information that I may have overlooked or any guidance or recommendations you may have to speed up init buildroot process on QEMU builder.