Is it me or does this article completely ignore two huge downsides with mmap - number one is that page faults are expensive, number two is that i/o failures become bad pointer dereferences.
Page faults are no more expensive than any other physical I/O. If the data you want isn't already in cache, a seek()/read() is as expensive as a page fault. Moreso really, because the read has to do a buffer copy too.
