-If the time is never advanced, this loop will clearly never end as MPI_Wtime()
-always returns the same value. Hence, pass a (small) value to the smpi/wtime
-option to force a call to MPI_Wtime to advance the time as well.
-
+When the option smpi/wtime is set to 0, the time advances only on
+communications and computations, so the previous code results in an
+infinite loop: the current [simulated] time will never reach @c
+some_time_bound. This infinite loop is avoided when that option is
+set to a small amount, as it is by default since SimGrid v3.21.
+
+Note that if your application does not contain any loop depending on
+the current time only, then setting this option to a non-zero value
+will slow down your simulations by a tiny bit: the simulation loop has
+to be broken and reset each time your code ask for the current time.
+If the simulation speed really matters to you, you can avoid this
+extra delay by setting smpi/wtime to 0.