I had a G+ thread about mmap a couple months ago that surfaced a lot of really good points. I like mmap a lot, but there are certainly some down sides:
If you're looking for an easy way to exploit mmap in your code, Cap'n Proto is a serialization format that works similarly to Protocol Buffers but is designed to work well with mmap():
https://plus.google.com/u/0/+KentonVarda/posts/NKUUzx2nEsN
If you're looking for an easy way to exploit mmap in your code, Cap'n Proto is a serialization format that works similarly to Protocol Buffers but is designed to work well with mmap():
http://capnproto.org
(Disclosure: I am the author of Cap'n Proto... and also the former maintainer of protobufs.)