MPI Hello World - Revision history

Rmh325 at 05:07, 21 December 2022

2022-12-21T05:07:44Z

2022-09-24T17:53:38Z

MPI Hello World

2022-09-24T17:44:19Z

2022-09-24T17:41:56Z

MPI Hello World

2022-09-24T17:39:35Z

2022-09-24T17:37:05Z

MPI Hello World

2022-09-24T17:29:45Z

MPI Hello World

2022-09-24T17:25:59Z

MPI Hello World

2022-09-24T17:10:40Z

MPI Hello World

2022-09-24T17:06:52Z

MPI Hello World

@@ Line 70: / Line 70: @@
  </nowiki>
-and keep adding lines until you get to <tt> pnode40 slots=4 max_slots=8 </tt>.
+and keep adding lines until you get to <tt> pnode64 slots=4 max_slots=8 </tt>.
 The next step assumes you have set up your ssh keys as described in [[Cluster SSH access]]
-With 40 nodes listed in your <tt> cluster_hosts </tt> file, run your program again with
+With 64 nodes listed in your <tt> cluster_hosts </tt> file, run your program again with
  mpirun --hostfile cluster_hosts ./hello_mpi
-You should see the output shown below, which is 160 lines long, four responses from each host, one for each core described.
+You should see the output shown below, which is 256 lines long, four responses from each host, one for each core described.
 Once you are able to run this program successfully, your MPI setup is working. This will be necessary before you can run other MPI-based programs, such as ipyparallel programs which use MPI.
  <nowiki>

@@ Line 15: / Line 15: @@
 int main(int argc, char* argv[])
+{
-    int rank, size, len;
+    int rank, size;
     MPI_Init(&argc, &argv);

@@ Line 1: / Line 1: @@
 == MPI Hello World ==
-Many parallel jobs are using [https://en.wikipedia.org/wiki/Message_Passing_Interface MPI] at the lowest level to manage parallel compute resources.
+Many parallel jobs are using [https://en.wikipedia.org/wiki/Message_Passing_Interface MPI] at the lowest level to manage parallel compute resources. You will want to successfully run this example to make sure your parallel computing environment is working properly. These instructions assume you've already set up your cluster ssh keys, as described in [[Cluster SSH access]]
 This is a 'Hello World' program that will test the operation of sending jobs to remote workers.
@@ Line 73: / Line 73: @@
 and keep adding lines until you get to <tt> pnode40 slots=4 max_slots=8 </tt>.
-The next step assumes you have set up your ssh keys as described in [[Cluster SSH Access]]
+The next step assumes you have set up your ssh keys as described in [[Cluster SSH access]]
 With 40 nodes listed in your <tt> cluster_hosts </tt> file, run your program again with

@@ Line 1: / Line 1: @@
 == MPI Hello World ==
-Many parallel jobs are using MPI at the lowest level to manage parallel compute resources.
+Many parallel jobs are using [https://en.wikipedia.org/wiki/Message_Passing_Interface MPI] at the lowest level to manage parallel compute resources.
 This is a 'Hello World' program that will test the operation of sending jobs to remote workers.

@@ Line 44: / Line 44: @@
 Now, to run your mpi program on the cluster, you will need to create a hostfile.
 First, lets create a simple hostfile that just runs four processes on the local machine
  <nowiki>
@@ Line 49: / Line 52: @@
  </nowiki>
 Now run your program with that hostfile, using
  mpirun --hostfile localhost ./hello_mpi
@@ Line 68: / Line 71: @@
  </nowiki>
-and keep adding lines until you get to <tt> pnode40 </tt>.
+and keep adding lines until you get to <tt> pnode40 slots=4 max_slots=8 </tt>.
 The next step assumes you have set up your ssh keys as described in [[Cluster SSH Access]]

← Older revision		Revision as of 17:29, 24 September 2022
Line 59:		Line 59:
	Hello, world, I am 3 of 4		Hello, world, I am 3 of 4
	</nowiki>		</nowiki>
		+
		+	Now create a hostfile called <tt> cluster_hosts </tt> with the following entries:
		+	<nowiki>
		+	pnode01 slots=4 max_slots=8
		+	pnode02 slots=4 max_slots=8
		+	pnode03 slots=4 max_slots=8
		+	pnode04 slots=4 max_slots=8
		+	</nowiki>
		+
		+	and keep adding lines until you get to <tt> pnode40 </tt>.
		+
		+	The next step assumes you have set up your ssh keys as described in
		+	With 40 nodes listed in your <tt> cluster_hosts </tt> file, run your program again with
		+
		+	mpirun --hostfile cluster_hosts ./hello_mpi

@@ Line 28: / Line 28: @@
  </nowiki>
-create a folder and save this file as <code>hello_mpi.c</code>
+create a folder and save this file as <tt> hello_mpi.c </tt>
 You can compile this program with
-mpicc -g hello_mpi.c -o hello_mpi
+ mpicc -g hello_mpi.c -o hello_mpi
-You now have an executable called hello_mpi
+You now have an executable called <tt> hello_mpi </tt>
 You can run the command with
-mpirun ./hello_mpi
+ mpirun ./hello_mpi
 With no other arguments, mpirun will run all of the tasks on the local machine, usually one for each CPU core. You should see a hello world from each process, on each cpu core.
@@ Line 48: / Line 49: @@
  </nowiki>
-Put that line in a file called 'localhost'.
+Put that line in a file called <tt>localhost </tt>.
 Now run your program with that hostfile, using
-mpirun --hostfile localhost ./hello_mpi
+ mpirun --hostfile localhost ./hello_mpi
  <nowiki>

@@ Line 28: / Line 28: @@
  </nowiki>
-create a folder and save this file as helloworld_mpi.c
+create a folder and save this file as hello_mpi.c
 You can compile this program with
-mpicc -g helloworld_mpi.c -o helloworld_mpi
+mpicc -g hello_mpi.c -o hello_mpi
-You now have an executable called helloworld_mpi
+You now have an executable called hello_mpi
 You can run the command with
-mpirun ./helloworld_mpi
+mpirun ./hello_mpi
 With no other arguments, mpirun will run all of the tasks on the local machine, usually one for each CPU core. You should see a hello world from each process, on each cpu core.
@@ Line 50: / Line 50: @@
 Put that line in a file called 'localhost'.
 Now run your program with that hostfile, using
-mpirun --hostfile localhost ./helloworld_mpi
+mpirun --hostfile localhost ./hello_mpi
  <nowiki>
-Hello, world, I am 2 of 4, (Open MPI v4.0.3, package: Debian OpenMPI, ident: 4.0.3, repo rev: v4.0.3, Mar 03, 2020, 87)
+Hello, world, I am 0 of 4
-Hello, world, I am 0 of 4, (Open MPI v4.0.3, package: Debian OpenMPI, ident: 4.0.3, repo rev: v4.0.3, Mar 03, 2020, 87)
+Hello, world, I am 2 of 4
-Hello, world, I am 1 of 4, (Open MPI v4.0.3, package: Debian OpenMPI, ident: 4.0.3, repo rev: v4.0.3, Mar 03, 2020, 87)
+Hello, world, I am 1 of 4
-Hello, world, I am 3 of 4, (Open MPI v4.0.3, package: Debian OpenMPI, ident: 4.0.3, repo rev: v4.0.3, Mar 03, 2020, 87)
+Hello, world, I am 3 of 4
  </nowiki>