Benchmark: timing 3000000 iterations of changestat, openfile...
changestat:  4 wallclock secs ( 3.88 usr + -0.02 sys = 3.86 CPU) @ 778008.30/s (n=3000000)
openfile:  0 wallclock secs ( 1.01 usr + -0.02 sys =  0.99 CPU) @ 3024193.55/s (n=3000000)