Scheduled Downtime
On Friday 21 April 2023 @ 5pm MT, this website will be down for maintenance and expected to return online the morning of 24 April 2023 at the latest

Running LES in multiprocessing mode

This post was from a previous version of the WRF&MPAS-A Support Forum. New replies have been disabled and if you have follow up questions related to this post, then please start a new thread from the forum home page.

HP1801

New member
I am trying to run WRF-LES model and have compared running it with a single processor using
Code:
./wrf.exe
and in multiprocessing with 6 cores using
Code:
mpirun -np 6 ./wrf.exe
, however, I did not notice any differences in run times for the simulator. Is this normal or am I missing something?
 
Hi,
Just to verify, did you compile the model 2 different ways - serially, and then with dmpar and an MPI-type library (for parallel computing)?

If so, can you do the same test again and when running it serially, send the output to a log file:
Code:
./wrf.exe >& log.wrf

then please attach that log.wrf file, along with the rsl.out.0000 file from your parallel run, along with your namelist.input file so that I can take a look? Thanks!
 
kwerner said:
Hi,
Just to verify, did you compile the model 2 different ways - serially, and then with dmpar and an MPI-type library (for parallel computing)?

If so, can you do the same test again and when running it serially, send the output to a log file:
Code:
./wrf.exe >& log.wrf

then please attach that log.wrf file, along with the rsl.out.0000 file from your parallel run, along with your namelist.input file so that I can take a look? Thanks!

During ./configure, I picked option 35 (dm+sm) for GNU (gfortran/gcc). I am not sure which library from the list is for multiprocessing. From what I understood dm+sm should support both? Sorry I am a bit new to this.
Do you mean I need to compile the library serially first and then with dmpar option separately?
 
Hi,
dm+sm is a distributed memory, plus shared memory option for compiling. We actually don't usually recommend using the dm+sm option because it has caused many people problems, and we don't test it here. I would advise compiling with only dmpar (distributed memory). Then you can run a test with 1 processor, and again with 6 processors to see if you get timing differences. When running with each, use the mpirun command, but just change the number of processors:
Code:
mpirun -np 1 ./wrf.exe
Code:
mpirun -np 6 ./wrf.exe

You can compare the times you find in the rsl.out.0000 files for each of these tests to see timing results.
 
kwerner said:
Hi,
dm+sm is a distributed memory, plus shared memory option for compiling. We actually don't usually recommend using the dm+sm option because it has caused many people problems, and we don't test it here. I would advise compiling with only dmpar (distributed memory). Then you can run a test with 1 processor, and again with 6 processors to see if you get timing differences. When running with each, use the mpirun command, but just change the number of processors:
Code:
mpirun -np 1 ./wrf.exe
Code:
mpirun -np 6 ./wrf.exe

You can compare the times you find in the rsl.out.0000 files for each of these tests to see timing results.

Alright I will try this, thank you so much! I I still have problems I will let you know.
 
Top