Abaqus - Simulation time vs mesh size

Hallo everyone,

I want to estimate the how much simulation is taking time if i optimize the mesh size. How could i estimate that?

In the msg file there are four times (pic attached ). USER TIME (SEC) , SYSTEM TIME (SEC) , 
TOTAL CPU TIME (SEC), and WALLCLOCK TIME (SEC) which time should be consider to know how much simulation is taking time ? please guide me in this regard.

Abaqus ​​​​​​​