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 http://www.eng.auburn.edu/~xqin xqin@auburn.edu 31 Min: Lec07b-MPI 10 Slides 10 Min: Demonstration using putty Login ssh aubxxq@dmc.asc.edu module load openmpi mpicc hello.c –o hello mpirun –np 4 hello 9 min: This lecture note Lec07b-Alabama Supercomputer

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 user_name@dmc.asc.edu      ssh user_name@uv.asc.edu      ssh user_name@altix.asc.edu

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

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)

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)

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)

HPC User Manual http://www.asc.edu/html/man.pdf