irb(main):015:0> Benchmark.measure { 1000000.times { |i| i + 1 } }
=> 
#<Benchmark::Tms:0x400fa914 @cutime=0.0, @label="", @stime=0.0,
@real=0.514808893203735, @utime=4.95, @cstime=0.0, @total=4.95>

Why is user time bigger than real time?  I'm confused by the
relationship between these numbers.