I'll need to dig into what AIM7 actually does in this benchmark, which
isn't too easy as I'm on a business trip currently, but from the list
below it looks like it keeps overwriting and overwriting a file that's
already been allocated.  This is a pretty stupid workload, but fortunately
it should also be able to be optimized by skipping the actual block
lookup, which is what the old buffer.c code happens to do.