That could explain why using mmap is faster than read in general, but what about skipping bytes? It sounds to me like if the seek distance is less than a page s

That could explain why using mmap is faster than read in general, but what about skipping bytes? It sounds to me like if the seek distance is less than a page size, the kernel would need to fill the entire page with data. Then again, hard drives return minimum sized blocks of data anyway, which is sized in kilobytes. So I'm guessing the "skipping" is a performance benefit only as so far as user space goes. One would really have to grep a long string to be able to skip more than a block/page!