Mmap - I can't think of a scenario where it improves over read or write in the context discussed here: async access. Mmap is synchronous, and you can't do select/poll on it.

Not sure why you were downvoted.

That's some seriously hairy stuff there. I reckon I'd move to building my app as a kernel module more readily than trying to make a robust async arrangement using that mechanism :) Call me demanding, but I think we should can reasonably expect easier access to async from our OS than this mechanism offers.

On that topic of which.. how's the future of operating systems coming along?