Having written a commercial memory allocator a quarter century ago, I remember dealing with freelists, and decided they were too much of a pain to manage if fragmentation got out of control. I chose a different architecture that was less fragile under load. Interesting that this can still be an issue even on today's hardware.

It's also interesting how much a tiny detail can derail a huge organization. My former employer lost all services worldwide because of a single incorrect routing in a DNS server.