# Parallel environments

Parallel environments are programming environments designed for parallel computing in clusters. The environments enable execution of shared-memory and distributed-memory parallel applications. The most common parallel environments are Message Passing Interface (MPI) for distributed-memory machines, and OpenMP for shared-memory machines.

There are two parallel environments configured in the cluster. orte defines openMPI based environment for running MPI programs, can be invoked with -pe orte [num_slots] in the terminal or in the qsub script. However, most of the time you will be using smp environment which is for shared-memory jobs with multi-threading. This can be invoked by -pe smp [number of slots] option.

qconf -sp orte and qconf -sp smp will give you more info on the exact settings of each parallel environment.