This is a very interesting link. I didn't expect mmap to be less performant than read() calls.

I now wonder which use cases would mmap suit better - if any...

> All running processes share the mapped copy of the file.

So something like building linkers that deal with read only shared libraries "plugins" etc ..?

One reason to use shared memory mmap is to ensure that even if your process crashes, the memory stays intact. Another is to communicate between different processes.