How to continue a simulation from restart/dump files?

[Jiyuan]

Hi everyone,

I am running a simulation with Basilisk and I generate restart/dump files during the run. My question is: after stopping a case (either by Ctrl+C or after it finishes generating a dump file), how can I continue running it from the last saved state?

For context, my current workflow is:

# Compile the serial version
qcc -o tangaroa tangaroa.c -lm -L$BASILISK/gl -lglutils -lfb_tiny

# Run the serial version to generate a restart file
./tangaroa 

# Compile the MPI version with dump file support
qcc -source -D_MPI=1 -DDUMP=1 tangaroa.c
mpicc -DDUMP=1 -Wall -std=c99 -D_XOPEN_SOURCE=700 -O2 _tangaroa.c -o tangaroa_mpi \
      -lm -L/home/sjy/basilisk/src/gl -lglutils -lfb_tiny

# Run the MPI version, which generates dump files periodically
mpirun -np 4 ./tangaroa_mpi 

After stopping the run, I am not sure how to restart the simulation from the last saved state. Could anyone please advise the recommended way to continue a case?

Thanks in advance!

[Edoardo Cipriano]

Hi,

Take your last snapshot-%d/dump-%d file and rename it "restart".

As you can see at line 169 of tangaroa.c, the restore() function looks for a file called restart.

Alternatively, you can include:

https://www.basilisk.fr/src/maxruntime.h

which creates a "restart" file before stopping a simulation, after a given time, expressed as:

mpirun -np 4 ./tangaroa --maxruntime h:m:s

Best,

Edoardo

[Jiyuan]

Dear Edoardo,

Thank you very much for your help. I was able to successfully solve the problem using the second method. I would like to clarify one more point: is it possible to run the simulation directly with MPI from the beginning, rather than first running it in serial to generate a restart file and then switching to parallel?

Best regards,

Jiyuan

[Edoardo Cipriano]

Hi Jiyuan,

Yes, it is possible to run the simulation directly with MPI from the beginning, because the function dump() is able to write a snapshot file even when using MPI. Therefore, there is no need to generate the restart file in serial, you can use MPI from the beginning.

Best,

Edoardo