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Oklahoma State University
High Performance Computing Center

A unit in the Division of the Vice President for Research

PPN - Job Submission Scripts

For applications that run within a single compute node:

Each compute node on Cowboy has 12 processors (or cores) and 32 GB of RAM.

If your code only utilizes a single core, it is better to only request a single core (#PBS -l nodes=1:ppn=1.) 

HOWEVER, if your code can use all 12 cores efficiently, request all 12 cores in your job script (#PBS -l nodes=1:ppn=12.)
NOTE** if your application uses more than 2.5 GB RAM, then you will need to request more cores to correspond to the amount of RAM your application uses. For example:
  • If your code needs all 32 GB RAM you want to request all the cores of the node so that your job has exclusive use of the node: #PBS -l nodes=1:ppn=12.
  • If your code needs 16 GB RAM, then you only need to request half the node, or 6 cores: #PBS -l nodes=1:ppn=6. In this situation, if you submit 2 jobs, then both of them may run on the same node.
  • In summary, request 1 core for each 2.5 GB RAM that your application needs.
  • If your application needs more than 32GB (shared) RAM, please use the bigmem queue. The bigmem nodes have 256 GB RAM and 12 cores. Request 1 core for each 20 GB RAM your code requires.
#PBS -q batch
#PBS -l nodes=1:ppn=12
#PBS -l walltime=24:00:00
#PBS -j oe
module load <software_module_name>
<put the commands to run your application here>
For applications using MPI (applications that can use more than one compute node):
#PBS -q batch
#PBS -l nodes=16:ppn=12
#PBS -l walltime=24:00:00
#PBS -j oe
module load mvapich2-1.8/intel

NP=`cat $PBS_NODEFILE | wc -l`
mpirun -np ${NP} ./yourexecutable
(**Note** the usage of the backtick (or accent grave) character in the NP line. It is not the apostrophe, but the key in the upper left corner of they keyboard that has the tilde ~ character.)