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--- manual:parallel_execution [2014/09/12 10:44] – Updates tutorial with new syntax for example. zenke
+++ manual:parallel_execution [2014/10/14 17:32] – Adds paragraph on cluster computation. zenke
@@ Line 6: / Line 6: @@
 </code>
-Suppose you would like to run the same code in parallel. Suppose you have a running MPI implementation like OpenMPI, all you need to do is to use the following syntax:
+Suppose you would like to run the same code in parallel and assuming you have a running MPI implementation like OpenMPI, all you need to do is to use the following syntax:
 <code shell>
 mpirun -n 4 ./sim_coba_benchmark --dir /tmp --simtime 5
 </code>
 where ''-n 4'' specifies the number of processes to be run in parallel to be four. Now if everything worked correctly you should have already felt an increase in performance -- i.e. the program should have terminated its computation more quickly.
+To use multiple machines as a cluster the specifics might be different depending on the MPI implementation used. For OpenMPI it suffices, if the same home directory is mounted on all machines, to add a hostfile containing the names of all machines in the luster to the command line (e.g. ''mpirun -n 32 -f hostfile.mpi ./sim_background''). However, since for MPICH2 and other implementations the workflow is slightly different, I would recommend the user to look at the respective tutorials corresponding to their local MPI flavor.