[seabrookmx]

They are extremely different workloads so.. everything?

The CDN servers are basically appliances, and are often embedded in various data centers (includes those ran by ISP's) to aggressively cache content. They care about high throughput and run a single workload. Being able to fine tune the entire stack, right down to the TCP/IP implementation is very valuable in this case. Since they ship the hardware and software, they can tightly integrate the two.

By contrast, API workloads are very heterogeneous. I'd have to imagine the ability to run any standard Linux software there would also be a big plus. Linux clearly has much more vetting on cloud providers than FreeBSD as well.

[aflag]

Can't you fine tune linux as well? Does FreeBSD perform better somehow on a CDN workload? I find it difficult to imagine that the reason is performance. But I don't know what the reason is.

[craftkiller]

Netflix discusses their reasons starting at 18:20: https://www.youtube.com/watch?v=veQwkG0WdN8&t=18m20s

tl;dw: the performance, the efficiency of development, the community, FreeBSD is a complete operating system, the code base is smaller, the ports system, and the license.

and this video covers the optimizations Netflix has made to FreeBSD: https://www.youtube.com/watch?v=36qZYL5RlgY

Also potentially a reason: According to drewg123, Linux's kTLS was broken. Which I see drewg123 also commenting in this thread. Is he the "Drew on my team" mentioned in the first video? Is he the speaker in the 2nd video? Idk https://news.ycombinator.com/item?id=28585008