Hi Mohammed,
regarding CentOS CI slowness - you are not alone, kola is experiencing it too.
Some time ago I asked around and discovered that various projects experience noticeable CI slowness using CentOS compared to Ubuntu.
The hit is more noticeable on image building than deploying and I guess since OSA does "building/installing" while deploying, it experiences our worse hit.
We deploy in containers so I even checked the host:Ubuntu, container:CentOS scenario but it was noticeably slower anyway.
Hence it seems related to some CentOS libraries or common stuff (like Python maybe?), not kernel.
We even ran into broken CI situation by being hit by horizon changing translation-related internals and our once hacky way of compiling translations which resulted in n^2 compilations instead of n - Ubuntu was a bit slower than usual but CentOS timed out, possibly not even halfway through horizon image building process...
Kind regards,
Radek