GNU Compilers

To configure your environment for use of the GNU compilers, run the following command (you may have to unload your selected compiler - if an error message appears, it will provide instructions): module load gnu.  The default version will be loaded. To select a particular GNU version, use module load gnu/version. For example, use module load gnu/4.8.5 to load GNU 4.8.5.

Once the module is loaded, follow the guides below for compile commands:

Language	non-mpi	mpi
Fortran 90 or 95	gfortran	mpif90
Fortran 77	gfortran	mpif77
c	gcc	mpicc
c++	g++	mpicxx

The GNU compilers recognize the following command line options :

Compiler Option	Purpose
-fopenmp	Enables compiler recognition of OpenMP directives (except mpif77)
-o FILENAME	Specifies the name of the object file
-O0 or no -O  option	Disable optimization
-O1 or -O	Ligh optimization
-O2	Heavy optimization
-O3	Most expensive optimization (Recommended)

There are numerous flags that can be used. For more information run man <compiler binary name>.

When you log into owens.osc.edu you are actually logged into a linux box referred to as the login node. To gain access to the mutiple processors in the computing environment, you must submit your job to the batch system for execution. Batch jobs can request mutiple nodes/cores and compute time up to the limits of the OSC systems. Refer to Queues and Reservations and Batch Limit Rules for more info. 

Interactive Batch Session

For an interactive batch session, one can run the following command:

sinteractive -A <project-account> -N 1 -n 28 -l -t 1:00:00

which gives you 1 node and 28 cores (-N 1 -n 28),  with 1 hour (-t 1:00:00).  You may adjust the numbers per your need.

Non-interactive Batch Job (Serial Run)

A batch script can be created and submitted for a serial or parallel run. You can create the batch script using any text editor you like in a working directory on the system of your choice. The following example batch script file will use the input file named hello.c and the output file named hello_results. 
Below is the example batch script (job.txt) for a serial run:

#!/bin/bash
#SBATCH --time=1:00:00
#SBATCH --nodes=1 --ntasks-per-node=28
#SBATCH --job-name jobname
#SBATCH --account=<project-account>

module load gnu
cp hello.c $TMPDIR
cd $TMPDIR
gcc -O3 hello.c -o hello
./hello > hello_results
cp hello_results $SLURM_SUBMIT_DIR

In order to run it via the batch system, submit the job.txt file with the following command:

sbatch job.txt

Non-interactive Batch Job (Parallel Run)

Below is the example batch script (job.txt) for a parallel run:

#!/bin/bash
#SBATCH --time=1:00:00
#SBATCH --nodes=2 --ntasks-per-node=28 
#SBATCH --job-name jobname
#SBATCH --account=<project-account>

module load gnu
mpicc -O3 hello.c -o hello
cp hello $TMPDIR
cd $TMPDIR
mpiexec ./hello > hello_results
cp hello_results $SLURM_SUBMIT_DIR

To configure your environment for use of the GNU compilers, run the following command (you may have to unload your selected compiler - if an error message appears, it will provide instructions): module load gnu.  The default version will be loaded. To select a particular GNU version, use module load gnu/version. For example, use module load gnu/8.1.0 to load GNU 8.1.0.

Once the module is loaded, follow the guides below for compile commands:

LANGUAGE	NON-MPI	MPI
Fortran 90 or 95	gfortran	mpif90
Fortran 77	gfortran	mpif77
c	gcc	mpicc
c++	g++	mpicxx

The GNU compilers recognize the following command line options :

COMPILER OPTION	PURPOSE
-fopenmp	Enables compiler recognition of OpenMP directives (except mpif77)
-o FILENAME	Specifies the name of the object file
-O0 or no -O  option	Disable optimization
-O1 or -O	Ligh optimization
-O2	Heavy optimization
-O3	Most expensive optimization (Recommended)

 

 

 

 

 

 

There are numerous flags that can be used. For more information run man <compiler binary name>.