[kragen]

Perhaps surprisingly, I agree with your entire comment from beginning to end.

Sometimes mmap can be a real win, though. The poster child for this is probably LMDB. Varnish also does pretty well with mmap, though see my caveat on that in my linked comment.

[bcrl]

Varish was very well done. It's disappointing that with HTTPS-first nowadays there is very little oppourtunity to make good use of local web caches of web content across browsers / clients. Caches would have been a godsend back in the 1990s when we had to use shared dialup to connect to the internet while using NetScape in a classroom full of computers.

[kragen]

Yeah. But it sees a lot of reverse proxy use, and projects like IPFS are exploring the possibilities of securely-locally-cacheable data.