Timing difference with linux command time

[Riccardo Nigrelli]

I wrote a benchmark with 10 iterations and 20 repetitions.

The execution is wrapped with the unix command `time` to get the peak memory.

When the execution is ended, I notice a substantial difference:

This is the gbencmark result:

```

"real_time": 1.1915376993454993e+03,

"cpu_time": 1.1907871268750000e+03,

"time_unit": "ms"

```

the `time` result:

User time (seconds): 237.99
System time (seconds): 15.24

As you can see, there is a big difference. Why?
The difference it may be due that the `time` include all the 20 repetions? If yes, how I can compute the single repetition? Only divide by 20?