How to execute a MPI job
===================================

Description
--------------- 
Intel MPI is available on all servers for MPI environment. In addition, nvhpc's Open MPI is also available on the XD670.

Usage(IntelMPI)
--------------- 
Use mpirun command to execute a job. 

.. command-format::

   mpirun [ -np parallel number] [ -ppn parallel number per node ] program

.. attention::
 To improve job performance, specify values so that:

 [Parallel number(the value of "-np")] = [Number of nodes(the value of "#PBS -l select=")] ×[Parallel number per node(the value of "-ppn")]


Example
----------------

.. code-block:: none

   #!/bin/bash 
   #PBS -l select=1 
   
   cd $PBS_O_WORKDIR

   module load oneapi 2> /dev/null
   mpirun -np 56 /work/app/ABINIT/abinit-10.2.7_cpu/bin/abinit < input.files > result.out 2> result.err


Usage(OpenMPI)
--------------- 
Use mpirun command to execute a job. 

.. command-format::

   mpirun [ -np parallel number] [ -N parallel number per node ] -hostfile $PBS_NODEFILE -x LD_LIBRARY_PATH -x HCOLL_MAIN_IB=all program

.. attention::
 To improve job performance, specify values so that:

 [Parallel number(the value of "-np")] = [Number of nodes(the value of "#PBS -l select=")] ×[Parallel number per node(the value of "-N")]


Example
----------------

.. code-block:: none

   #!/bin/bash 
   #PBS -l select=1:ncpus=4:ngpus=4
   
   cd $PBS_O_WORKDIR

   module load nvhpc > /dev/null
   mpirun -np 4 -N 4 -hostfile $PBS_NODEFILE -x LD_LIBRARY_PATH -x HCOLL_MAIN_IB=all /work/app/VASP6/vasp.6.5.1_gpu/bin/vasp_std > vasp.out 2> vasp.err