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. Mor

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. Fair point about I/O failures though.