Rocky MPI Hello World - Revision history

Jondale at 19:31, 12 January 2026

2026-01-12T19:31:35Z

← Older revision		Revision as of 19:31, 12 January 2026
Line 67:		Line 67:
	mpicc -O2 -o hello_mpi hello_mpi.c		mpicc -O2 -o hello_mpi hello_mpi.c
	</pre>		</pre>

			This creates the binary file <code>hello_mpi</code> that we will run in our job.

	== Step 3 — Submit an MPI batch job (mpi_hello.sbatch) ==		== Step 3 — Submit an MPI batch job (mpi_hello.sbatch) ==

Jondale at 19:01, 12 January 2026

2026-01-12T19:01:27Z

← Older revision		Revision as of 19:01, 12 January 2026
Line 2:		Line 2:

	== Supported versions ==		== Supported versions ==

			Rocky supports PMIx v3 for MPI process management. MPI applications should be launched via srun using --mpi=pmix_v3.

	To see what versions of OpenMPI are available use the following command:		To see what versions of OpenMPI are available use the following command:
Line 68:		Line 70:
	== Step 3 — Submit an MPI batch job (mpi_hello.sbatch) ==		== Step 3 — Submit an MPI batch job (mpi_hello.sbatch) ==

	Create the batch file that we'll name mpi_hello.sbatch		Create the batch file that we'll name <code>mpi_hello.sbatch</code>.<br/>
			Notice that we are using <code>--mpi=pmix_v3</code> as a parameter to srun.
	<syntaxhighlight lang="bash">		<syntaxhighlight lang="bash">
	#!/usr/bin/env bash		#!/usr/bin/env bash

Jondale at 18:55, 12 January 2026

2026-01-12T18:55:52Z

← Older revision		Revision as of 18:55, 12 January 2026
Line 1:		Line 1:
	= MPI Jobs on Rocky =		= MPI Jobs on Rocky =

	== Supported ~~MPI Stack~~ ==		== Supported versions ==

	~~We currently recommend and support~~:		To see what versions of OpenMPI are available use the following command:

	* '''OpenMPI ~~4.1.6'''~~		<syntaxhighlight lang="bash">
	* '''PMIx 4.2.6'''		module spider OpenMPI
			</syntaxhighlight>

	''OpenMPI 5~~+ will be supported with a future software upgrade''~~		As of the writing of this document the versions available:
			<pre>
			Versions:
			OpenMPI/3.1.1-GCC-7.3.0-2.30
			OpenMPI/3.1.3-GCC-8.2.0-2.31.1
			OpenMPI/3.1.4-GCC-8.3.0
			OpenMPI/4.0.3-GCC-9.3.0
			OpenMPI/4.0.5-GCC-10.2.0
			OpenMPI/4.1.1-GCC-10.3.0
			OpenMPI/4.1.1-GCC-11.2.0
			OpenMPI/4.1.4-GCC-11.3.0
			OpenMPI/4.1.4-GCC-12.2.0
			OpenMPI/4.1.5-GCC-12.3.0
			OpenMPI/4.1.6-GCC-13.2.0
			OpenMPI/5.0.3-GCC-13.3.0
			OpenMPI/5.0.7-GCC-14.2.0
			OpenMPI/5.0.8-GCC-14.3.0
			OpenMPI/5.0.8-llvm-compilers-20.1.8
			</pre>

	----		----
Line 41:		Line 60:
	== Step 2 — Compile the program ==		== Step 2 — Compile the program ==

			Load the appropriate version of OpenMPI you want to use and then compile your program with mpicc.
	<pre>		<pre>
	module load OpenMPI/4.1.6-GCC-13.2.0		module load OpenMPI/5.0.8-GCC-14.3.0
	mpicc -O2 -o hello_mpi hello_mpi.c		mpicc -O2 -o hello_mpi hello_mpi.c
	</pre>		</pre>
Line 48:		Line 68:
	== Step 3 — Submit an MPI batch job (mpi_hello.sbatch) ==		== Step 3 — Submit an MPI batch job (mpi_hello.sbatch) ==

			Create the batch file that we'll name mpi_hello.sbatch
	<syntaxhighlight lang="bash">		<syntaxhighlight lang="bash">
	#!/usr/bin/env bash		#!/usr/bin/env bash
Line 57:		Line 78:
	#SBATCH --time=00:05:00		#SBATCH --time=00:05:00

	module load OpenMPI/4.1.6-GCC-13.2.0		module load OpenMPI/5.0.8-GCC-14.3.0

	srun --mpi=pmix_v3 ./hello_mpi		srun --mpi=pmix_v3 ./hello_mpi
	</syntaxhighlight>		</syntaxhighlight>

	~~Submit~~ the job:
			Use sbatch to submit the job defined in our sbatch file:

	<pre>		<pre>

Jondale at 21:28, 9 January 2026

2026-01-09T21:28:27Z

← Older revision		Revision as of 21:28, 9 January 2026
Line 82:		Line 82:
	Hello from rank 7 of 8 on rocky5.rocky.nimbios.org		Hello from rank 7 of 8 on rocky5.rocky.nimbios.org
	</pre>		</pre>

	~~----~~

	~~= Quick Reference =~~

	~~{\| class="wikitable"~~
	~~! Action !! Command~~
	\|-
	~~\| Load MPI module \|\| <code>module load OpenMPI/4.1.6-GCC-13.2.0</code>~~
	\|-
	~~\| Recommended launch \|\| <code>srun --mpi=pmix_v3 ./my_program</code>~~
	\|-
	~~\| Alternative launch \|\| <code>mpirun ./my_program</code>~~
	\|-
	~~\| Avoid \|\| <code>srun --mpi=pmi2</code>, <code>srun --mpi=none</code>, OpenMPI 5~~
	\|}

Jondale at 21:27, 9 January 2026

2026-01-09T21:27:40Z

← Older revision		Revision as of 21:27, 9 January 2026
Line 60:		Line 60:

	srun --mpi=pmix_v3 ./hello_mpi		srun --mpi=pmix_v3 ./hello_mpi

	~~# optionally use mpirun instead of srun~~
	~~#mpirun -np "$SLURM_NTASKS" ./hello_mpi~~
	</syntaxhighlight>		</syntaxhighlight>

Jondale at 14:03, 16 December 2025

2025-12-16T14:03:29Z

← Older revision		Revision as of 14:03, 16 December 2025
Line 56:		Line 56:
	#SBATCH --ntasks=8		#SBATCH --ntasks=8
	#SBATCH --time=00:05:00		#SBATCH --time=00:05:00
	~~#SBATCH --partition=compute~~

	module load OpenMPI/4.1.6-GCC-13.2.0		module load OpenMPI/4.1.6-GCC-13.2.0

Jondale at 00:40, 16 December 2025

2025-12-16T00:40:50Z

← Older revision		Revision as of 00:40, 16 December 2025
Line 1:		Line 1:
	~~TBA~~		= MPI Jobs on Rocky =

			== Supported MPI Stack ==

			We currently recommend and support:

			* '''OpenMPI 4.1.6'''
			* '''PMIx 4.2.6'''

			''OpenMPI 5+ will be supported with a future software upgrade''

			----

			= MPI Example: Hello World in C =

			This example demonstrates compiling and running MPI across multiple nodes.

			== Step 1 — Create the MPI program (hello_mpi.c) ==

			<syntaxhighlight lang="c">
			#include <mpi.h>
			#include <stdio.h>

			int main(int argc, char *argv[]) {
			int rank, size, len;
			char name[MPI_MAX_PROCESSOR_NAME];

			MPI_Init(&argc, &argv);

			MPI_Comm_rank(MPI_COMM_WORLD, &rank);
			MPI_Comm_size(MPI_COMM_WORLD, &size);
			MPI_Get_processor_name(name, &len);

			printf("Hello from rank %d of %d on %s", rank, size, name);

			MPI_Finalize();
			return 0;
			}
			</syntaxhighlight>

			== Step 2 — Compile the program ==

			<pre>
			module load OpenMPI/4.1.6-GCC-13.2.0
			mpicc -O2 -o hello_mpi hello_mpi.c
			</pre>

			== Step 3 — Submit an MPI batch job (mpi_hello.sbatch) ==

			<syntaxhighlight lang="bash">
			#!/usr/bin/env bash
			#SBATCH --job-name=mpi-hello
			#SBATCH --output=mpi-hello-%j.out
			#SBATCH --error=mpi-hello-%j.err
			#SBATCH --nodes=2
			#SBATCH --ntasks=8
			#SBATCH --time=00:05:00
			#SBATCH --partition=compute

			module load OpenMPI/4.1.6-GCC-13.2.0

			srun --mpi=pmix_v3 ./hello_mpi

			# optionally use mpirun instead of srun
			#mpirun -np "$SLURM_NTASKS" ./hello_mpi
			</syntaxhighlight>

			Submit the job:

			<pre>
			sbatch mpi_hello.sbatch
			</pre>

			== Step 4 — Expected Output ==

			The generated output file (<code>mpi-hello-<jobid>.out</code>) should contain:

			<pre>
			Hello from rank 0 of 8 on rocky4.rocky.nimbios.org
			Hello from rank 1 of 8 on rocky4.rocky.nimbios.org
			Hello from rank 2 of 8 on rocky4.rocky.nimbios.org
			Hello from rank 3 of 8 on rocky4.rocky.nimbios.org
			Hello from rank 4 of 8 on rocky5.rocky.nimbios.org
			Hello from rank 5 of 8 on rocky5.rocky.nimbios.org
			Hello from rank 6 of 8 on rocky5.rocky.nimbios.org
			Hello from rank 7 of 8 on rocky5.rocky.nimbios.org
			</pre>

			----

			= Quick Reference =

			{\| class="wikitable"
			! Action !! Command
			\|-
			\| Load MPI module \|\| <code>module load OpenMPI/4.1.6-GCC-13.2.0</code>
			\|-
			\| Recommended launch \|\| <code>srun --mpi=pmix_v3 ./my_program</code>
			\|-
			\| Alternative launch \|\| <code>mpirun ./my_program</code>
			\|-
			\| Avoid \|\| <code>srun --mpi=pmi2</code>, <code>srun --mpi=none</code>, OpenMPI 5
			\|}

Jondale: Created page with "TBA"

2025-11-20T20:48:50Z

Created page with "TBA"

New page

TBA