I got the result of linux time command.
real 119m10.626s user 133m0.952s sys 20m32.155s
From the information I was looking for, it seems that user + sys should be less than real, but this is not the case here. Does anyone know why?
Multiple processors.
A multithreaded application can run simultaneously on several processor cores (and, thus, accumulate processor time as a multiplicity of real time)