openMP

Execution of parallel programs written with openMP is controlled by a number of environment variables.

The $OMP_NUM_THREDS variable controls how many threads to execute in parallel. This variable is set automatically by the batch system and it it not recommended that you change it. By default it is set to the ppn value from your qsub command no matter how many nodes were requested.

>qsub -I -q dev -l nodes=1:ppn=8
qsub: waiting for job 2756021.clusman0a.frank.sam.pitt.edu to start
qsub: job 2756021.clusman0a.frank.sam.pitt.edu ready
 
defusco@n317:~>env | grep OMP 
OMP_NUM_THREADS=8