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Task Farming OpenMP Programs on HPCx
However, it turns out that the program that is task-farmed doesn't actually have to be a serial program: all that is required is that it is not an MPI program. The three challenges with running multiple OpenMP jobs in this manner are:
In short, with tasks_per_node = 1, the number of processors you use is 16 times the value of cpus.
As an example, imagine a simple OpenMP "Hello World" program which simply prints "Hello" from each thread. Run in the following way:
#@ cpus=4 #@ tasks_per_node=1 export PATH=$PATH:/usr/local/packages/bin export OMP_NUM_THREADS=16 taskfarm "./omphello > omphello.%d.log"will use 64 processors to run four independent jobs each comprising 16 OpenMP threads. You should see four output files called omphello.0.log, omphello.1.log, etc., corresponding to each of the four jobs. Each log file should contain 16 "hello world" lines, one from each thread.
Before running a real OpenMP program in this manner I would recommend running a simple Hello World program as above to check that everything is working correctly.
I hope that this is useful!
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