Should I tell the user how much time a process took?

1. How do you check the time of a process?
2. Why user time is bigger than real time?

How do you check the time of a process?

You can use ps command to check the time a particular process has been running. You need to first find process ID then use it to find elapsed time. Then use ps with options -o etime to find elapsed running time. etime option displays elapsed time since the process was started, in the form [[DD-]hh:]mm: ss.

Why user time is bigger than real time?

In normal (all most all) GC events, real time will be less than user + sys time. It's because of multiple GC threads work concurrently to share the work load, thus real time will be less than user + sys time. Say user + sys time is 2 seconds.