Normally, MacPorts tries hosts in ping order. Without having looked at the code, I assume the same applies to preferred hosts: that they are tried in ping order, before any of the other hosts.
The list of download URLs is indeed sorted by host ping time. A stable sort algorithm is used, so hosts with identical ping times stay in the same relative order that they were originally in in archive_sites.tcl.
The way preferred_hosts works is to override the ping time of matching hosts to 0.
CDN throughput is poor everywhere. I need to figure out if there is a change I can make to the CDN settings to improve it. It has been a few years since I asked them about it. Maybe it's time to ask again.
It seems to be only the cache miss performance that is bad. Downloading directly from the nue.de origin server is much faster for the first fetch, but re-fetching a port I just fetched is faster via the CDN.
- Josh
