The clock-type parameter determines how ILOG CPLEX measures computation time. CPU time, the default, is most appropriate when only one processor is used. It reports the amount of time the CPU spent performing computation on behalf of your application. For parallel execution, CPU time is system dependent and generally will not reflect the desired metric. On some parallel systems, it may measure aggregate CPU time, that is, the sum of time used by all processors. On others, it may report the CPU time of only one process. In short, it may give you a misleading indication of parallel speed.

The alternative type, wall-clock time, is usually more appropriate for parallel computing because it measures the total physical time elapsed after an operation begins. When multiple processes are active, and when parallel optimizers are active, wall-clock time can be much different from CPU time.

You can choose the type of clock setting, in the:

Replace the i with the value 1 to specify CPU time or 2 to specify wall-clock time.