JLBS_mpi_4py_tutorial (#29)

Author: jlbs86

README.md

@@ -1,2 +1,90 @@
 # CuTonala_2024_A
 Parallel Programming Course
+
+=== Dependencies ===
+
+These programs depend on mpi4py (>= Version 3.1.5)
+
+The mpi4py documentation and installation instructions 
+can be found at:
+
+   http://mpi4py.scipy.org/
+
+=== How to run on a single (multi-core) host ===
+
+Run it with 
+
+ mpirun -np 4 ./some-program
+
+where the number after "-np " is the number of parallel MPI 
+processes to be started.
+
+
+=== How to run on multiple hosts ===
+
+If you want to run the program distributed over multiple hosts, 
+you have to create a <hostfile> which looks like:
+
+-- hostfile --
+host1   slots=4
+host2   slots=4
+host3   slots=4
+--------------
+
+Where "slots=" specifies the number of parallel processes that should be
+started on that host.
+
+Run it with
+
+  mpirun --hostfile <hostfile> ./some-program
+
+
+=== Run on a cluster with the Torque Job scheduling system ===
+
+The Torque HPC documentation and installation instructions 
+can be found at:
+
+Terascale Open-source Resource and QUEue manager (TORQUE) is a
+job scheduler/resource manager that employs PBS.
+Jobs can be run either interactively or as a submitted PVS
+batch script that is run non-interactively and subsequently
+controlled through TORQUE.
+
+   https://hpc-wiki.info/hpc/Torque
+   https://docs.adaptivecomputing.com/torque/3-0-5/1.1installation.php
+
+There are two possibilities:
+
+a) Run interactively:
+
+Request an interactive session and allocate a number of processors/nodes for 
+your session:
+
+ $ qsub -I X -l nodes=4:ppn=4
+
+Where "-I" means you want to work interactively, "-X" requests grapical
+(X-Window) I/O -- (you can run arbitrary programs that open windows).  The
+option "-l " specifies the resources you want to allocate.  "-l nodes=4:ppn=4"
+requests four compute nodes with each having four processor cores 
+[ppn =^ ProcessorsPerNode].  So in total you allocate 16 CPU cores. 
+[The scheduler is free to run your job on two nodes having 8 CPU cores each]
+
+Once your interactive session is ready, you run 
+
+ $ mpirun ./your-program
+  
+mpirun automatically knowns how many parallel processes have to be started and
+where they have to be started.
+
+b) Submit as non-interactive batch-job:
+
+Use 
+
+ $ qsub -l nodes=4:ppn=4 ./your-jobfile.job
+
+to submit jour job-file. Similar to the interactive case, "-l" again is used  
+to request resources from the scheduling system. The job file usually is a 
+simple shell script which specifies the commands to be run once your job 
+starts. In addition, the jobfile can contain "#PBS <something>" statements
+which are used to specify additional options which could have been specified 
+in the "qsub" commandline. Please see "man qsub" for details.