Programming/OpenMPI - Revision history

Pysdlb: /* C Example */

2023-08-23T15:22:19Z

‎C Example

Pysdlb at 13:18, 16 November 2022

2022-11-16T13:18:13Z

Pysdlb at 12:11, 2 November 2022

2022-11-02T12:11:27Z

Pysdlb at 12:54, 13 October 2022

2022-10-13T12:54:41Z

Pysdlb at 09:04, 24 May 2021

2021-05-24T09:04:41Z

Pysdlb at 10:51, 10 June 2019

2019-06-10T10:51:54Z

Pysdlb at 10:46, 10 June 2019

2019-06-10T10:46:52Z

Pysdlb at 10:46, 10 June 2019

2019-06-10T10:46:29Z

Pysdlb at 15:53, 9 January 2018

2018-01-09T15:53:30Z

Pysdlb at 14:50, 9 January 2018

2018-01-09T14:50:04Z

@@ Line 75: / Line 75: @@
          else
+         {
-                 MPI_Recv(&buf, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, &status);
+                 MPI_Bcast(&buf, 1, MPI_INT, 0, MPI_COMM_WORLD, &status);
                  printf("rank %d receiving received %d\n", rank, buf);
+         }

← Older revision		Revision as of 13:18, 16 November 2022
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−	~~==Navigation==~~

−	* [[Main_Page\|Home]]	+	[[Applications/OpenMPI\| Back to OpenMPI Application Page]] / [[Main Page]] / [[FurtherTopics/FurtherTopics #Modules\| Further Topics]]
−	* [[Applications\|Application ~~support~~]]
−	* [[~~General\|General~~]]
−	* [[~~Programming~~\|~~Programming support~~]] *

@@ Line 1: / Line 1: @@
 == Programming Details ==
-'''MPI''' defines not only point-to-point communication (e.g., send and receive), but it also defines other communication patterns, such as collective communication. Collective operations are where multiple processes are involved in single communication action. Reliable broadcast, for example, is where one process has a message at the beginning of the operation, and at the end of the operation, all processes in a group have the message.
+'''MPI''' defines not only point-to-point communication (e.g., send and receive), but also defines other communication patterns, such as collective communication. Collective operations are where multiple processes are involved in single communication action. Reliable broadcast, for example, is where one process has a message at the beginning of the operation, and at the end of the operation, all processes in a group have the message.
 Message-passing performance and resource utilization are the king and queen of high-performance computing. Open MPI was explicitly designed in such a way that it could operate at the very bleeding edge of high performance: incredibly low latencies for sending short messages, extremely high short message injection rates on supported networks, fast ramp-ups to maximum bandwidth for large messages, etc.
@@ Line 201: / Line 201: @@
 </pre>
-== Further Information ==
+== Next Steps ==
 * [http://mpitutorial.com/tutorials/ http://mpitutorial.com/tutorials/]

@@ Line 1: / Line 1: @@
 == Programming Details ==
-'''MPI''' defines not only point-to-point communication (e.g., send and receive), it also defines other communication patterns, such as collective communication. Collective operations are where multiple processes are involved in single communication action. Reliable broadcast, for example, is where one process has a message at the beginning of the operation, and at the end of the operation, all processes in a group have the message.
+'''MPI''' defines not only point-to-point communication (e.g., send and receive), but it also defines other communication patterns, such as collective communication. Collective operations are where multiple processes are involved in single communication action. Reliable broadcast, for example, is where one process has a message at the beginning of the operation, and at the end of the operation, all processes in a group have the message.
-Message-passing performance and resource utilization are the king and queen of high-performance computing. Open MPI was specifically designed in such a way that it could operate at the very bleeding edge of high performance: incredibly low latencies for sending short messages, extremely high short message injection rates on supported networks, fast ramp-ups to maximum bandwidth for large messages, etc.
+Message-passing performance and resource utilization are the king and queen of high-performance computing. Open MPI was explicitly designed in such a way that it could operate at the very bleeding edge of high performance: incredibly low latencies for sending short messages, extremely high short message injection rates on supported networks, fast ramp-ups to maximum bandwidth for large messages, etc.
 The Open MPI code has 3 major code modules:
@@ Line 18: / Line 18: @@
 * Message-Passing Parallel Programming
-The message-passing model can be thought of as a process together with the program's own data and the parallelism is achieved by having each of these processes co-operate on the same task. This model also has some limitations these are:
+The message-passing model can be thought of as a process together with the program's own data and the parallelism is achieved by having each of these processes cooperate on the same task. This model also has some limitations these are:
 * All variables are private to each process.
 * All communication between each process by sending and receiving messages (hence the OpenMPI name).
-* Most message passing programs use the Single-Program-Multiple-Data (SPMD) model.
+* Most message-passing programs use the Single-Program-Multiple-Data (SPMD) model.
-* It is possible to run an MPI type program on one or more nodes, although if your program is only ever intended to run on one node you should consider openMP instead here.
+* It is possible to run an MPI-type program on one or more nodes, although if your program is only ever intended to run on one node you should consider openMP instead here.
 Below is a data diagram of OpenMPI:
@@ Line 41: / Line 41: @@
 * ''Point to point'' - single point transfer call.
 * ''Broadcast'' - all data is transmitted to all processes.
-* ''Scatter/Gather data'' - parts of the data are sent to each process via a '''MPI_scatter''' call for processing. Then a '''MPI_gather''' call to bring the data back to a root process.
+* ''Scatter/Gather data'' - parts of the data are sent to each process via a '''MPI_scatter''' call for processing. Then a '''MPI_gather''' call brings the data back to a root process.
 * ''Reduction'' - Combine data from several processes to form a single result (ie. form a global sum, product, max, min, etc.).
 ====Communication considerations====
-* Sends and receive calls must match. If these are not there is a danger of deadlock and your program may stall!
+* Sends and receives calls must match. If these are not there is a danger of deadlock and your program may stall!
-* Most programs do not need to be complicated and scientific codes have a simple structure which in turn have simple communication patterns.
+* Most programs do not need to be complicated and scientific codes have a simple structure which in turn has simple communication patterns.
 * Use collective communication.

@@ Line 1: / Line 1: @@
 == Programming Details ==
-'''MPI''' defines not only point-to-point communication (e.g., send and receive), it also defines other communication patterns, such as collective communication. Collective operations are where multiple processes are involved in a single communication action. Reliable broadcast, for example, is where one process has a message at the beginning of the operation, and at the end of the operation, all processes in a group have the message.
+'''MPI''' defines not only point-to-point communication (e.g., send and receive), it also defines other communication patterns, such as collective communication. Collective operations are where multiple processes are involved in single communication action. Reliable broadcast, for example, is where one process has a message at the beginning of the operation, and at the end of the operation, all processes in a group have the message.
 Message-passing performance and resource utilization are the king and queen of high-performance computing. Open MPI was specifically designed in such a way that it could operate at the very bleeding edge of high performance: incredibly low latencies for sending short messages, extremely high short message injection rates on supported networks, fast ramp-ups to maximum bandwidth for large messages, etc.
@@ Line 18: / Line 18: @@
 * Message-Passing Parallel Programming
-The message passing model can be thought of a process together with the program's own data and the parallelism is achieved by having each of these processes co-operate on the same task. This model also has some limitations these are:
+The message-passing model can be thought of as a process together with the program's own data and the parallelism is achieved by having each of these processes co-operate on the same task. This model also has some limitations these are:
 * All variables are private to each process.
@@ Line 33: / Line 33: @@
 * Sending a message can either be synchronous or asynchronous. (eg. '''MPI_Ssend''' (Synchronous) and '''MPI_Bsend''' (Asynchronous)).
-* A synchronous send is not completed until the message has started to be received.
+* Asynchronous send is not completed until the message has started to be received.
 * An asynchronous send completes as soon as the message has gone.
 * Receives are usually synchronous - the receiving process must wait until the message arrives.
@@ Line 46: / Line 46: @@
 ====Communication considerations====
-* Sends and receive call must match. If these are not there is a danger of deadlock and your program may stall!
+* Sends and receive calls must match. If these are not there is a danger of deadlock and your program may stall!
 * Most programs do not need to be complicated and scientific codes have a simple structure which in turn have simple communication patterns.
 * Use collective communication.
@@ Line 160: / Line 160: @@
 </pre>
-'''Note''' : mpifort is a new name for the Fortran wrapper compiler that debuted in Open MPI v3.0.0
+'''Note''': mpifort is a new name for the Fortran wrapper compiler that debuted in Open MPI v3.0.0
@@ Line 179: / Line 179: @@
 #SBATCH -p compute
 #SBATCH --exclusive
 echo $SLURM_JOB_NODELIST

@@ Line 131: / Line 131: @@
 The following modules are available for OpenMPI:
-* module add gcc/4.9.3 (GNU compiler)
+* module add gcc/8.2.0 (GNU compiler)
-* module add intel/compiler/64/2016.2.181 (Intel compiler)
+* module add intel/2018 (Intel compiler)
-* module add openmpi/gcc/1.10.2
+* module add openmpi/3.0.0/gcc-8.2.0
-* module add openmpi/gcc/1.10.5
+* module add intel/mpi/64/2018
@@ Line 147: / Line 144: @@
 <pre style="background-color: black; color: white; border: 2px solid black; font-family: monospace, sans-serif;">
-[username@login01 ~]$ module add gcc/4.9.3
+[username@login01 ~]$ module add gcc/8.2.0
-[username@login01 ~]$ module add openmpi/gcc/1.10.5
+[username@login01 ~]$ module add openmpi/3.0.0/gcc-8.2.0
 [username@login01 ~]$ gcc -o testMPI testMPI.c
@@ Line 157: / Line 154: @@
 <pre style="background-color: black; color: white; border: 2px solid black; font-family: monospace, sans-serif;">
-[username@login01 ~]$ module add gcc/4.9.3
+[username@login01 ~]$ module add gcc/8.2.0
-[username@login01 ~]$ module add openmpi/gcc/1.10.5
+[username@login01 ~]$ module add openmpi/3.0.0/gcc-8.2.0
 [username@login01 ~]$ mpifort -o testMPI testMPI.f03
 </pre>
-'''Note''' : mpifort is a new name for the Fortran wrapper compiler that debuted in Open MPI v1.7.
+'''Note''' : mpifort is a new name for the Fortran wrapper compiler that debuted in Open MPI v3.0.0
@@ Line 186: / Line 183: @@
 module purge
-module add gcc/4.9.3
+module add gcc/8.2.0
-module add openmpi/gcc/1.10.5
+module add openmpi/3.0.0/gcc-8.2.0
 export I_MPI_DEBUG=5

← Older revision		Revision as of 10:46, 10 June 2019
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−	\|==Navigation==	+	==Navigation==

	* [[Main_Page\|Home]]		* [[Main_Page\|Home]]

@@ Line 213: / Line 213: @@
 * [[programming/Fortran|Fortran Programming]]
 * [[programming/Python|Python Programming]]
-{|
-|style="width:5%; border-width: 0" | [[File:icon_home.png]]
-|style="width:95%; border-width: 0" |
+|==Navigation==
 * [[Main_Page|Home]]
 * [[Applications|Application support]]
 * [[General|General]]
-* [[Training|Training]]
+* [[Programming|Programming support]] *

@@ Line 205: / Line 205: @@
 == Further Information ==
 * [[applications/OpenMPI|OpenMPI (Wiki)]]
 * [https://en.wikipedia.org/wiki/Open_MPI https://en.wikipedia.org/wiki/Open_MPI]