2. Auburn University http://www.eng.auburn.edu/~xqin
COMP7330/7336 Advanced Parallel and Distributed Computing Setting Up Your Programming Environment
Dr. Xiao Qin
Auburn University
31 Min: Lec07b-MPI 10 Slides
10 Min: Demonstration using putty
Login ssh
module load openmpi
mpicc hello.c –o hello
mpirun –np 4 hello
9 min: This lecture note Lec07b-Alabama Supercomputer

3. Login
The DMC, SGI Ultraviolet, and SGI Altix and can be accessed using secure shell.
Windows Machines: use PuTTY
Secure shell is installed on many Linux and Unix machines. Command line:
      ssh
     ssh
     ssh

4. Running MPI Interactive on DMC Option 1) Use the login node
Work run on the login node is limited to 10 minutes of CPU time and a small amount of memory.
You can run mpi jobs like this mpirun -np 4 myprogram
The login node has 16 cores.  
If 20 students try to run 4 core jobs at the same time, it will bog down the node to the point of making it unusable to everyone

5. Running MPI Interactive on DMC Option 2) Use a queue
Open an interactive session through the queue: qsub -I -q small-parallel -r n -l nodes=4,mem=2gb,partition=dmc
The terminal session hangs until the job starts on the compute nodes.
It may wait from a minute to a number of hours.
ASC provides a "class" queue and will reserve some processors for that queue so you don't have to wait on research work.
(but might wait for the other students in the same class)

6. Running MPI Interactive on DMC Option 2) Use a queue (cont.)
Once it has started an interactive session on the compute nodes, you may have to again load the module for the mpi you are using.  
Then run the mpi job like this: mpiexec myprogram
(but might wait for the other students in the same class)

7. Compile and Run an MPI Application
Load the module for the mpi:  
module load openmpi
Compile the program: mpicc myprogram.cpp –o myprogram
Compile the program: mpirun –np 4 myprogram
(but might wait for the other students in the same class)

8. HPC User Manual