MPI is not speeding up?

[Zhoujieliang]

hello,
I compile Noahmp with two version.
One is serial.

Another is mpi.

And use same data, same namelist, there is no difference in speed between the two when running ./hrldas.exe
How can I check if I have successfully compiled MPI?

[cenlinhe]

for mpi run, you will need to use the mpi run command instead of just ./hrldas.exe. The mpi run command will be slightly different in different computers or machines (https://www.open-mpi.org/doc/v4.0/man1/mpirun.1.php). you may try "mpirun -np 4 ./hrldas.exe" This means using 4 cores to run the model.

[Zhoujieliang]

Thank you, the speed has significantly improved.
Is it normal for the printed information to become four times?

[cenlinhe]

yes, because you used 4 cores so the info from each core will be displayed. If you use more cores, then more lines will be shown.