When you want to know how long does it take to run a process, just use time command as a prefix

$ time my_program arg1 arg2
real        0m0.003s
user        0m0.000s
sys         0m0.004s
  • real : wall clock time, mean time to start to finish your process
  • user : CPUs-time outside the kernel
  • sys : CPUs-time within the kernel

real+sys result is total multi CPUs time (so if you have a multi core CPUs, it is often bigger than real)