Unable to use all cores with mpirun

Question

I\'m testing a simple MPI program on my desktop (Ubuntu LTS 16.04/ Intel® Core™ i3-6100U CPU @ 2.30GHz × 4/ gcc 4.8.5 /OpenMPI 3.0.0) and mpirun won\'t let me use all of the cor

Answer 1

Use $ lscpu the number of cores per socket * number of sockets would give you number of physical cores(the ones that you can use for mpi) where as sockets per core * number of sockets * threads per core will give you number of logical cores(the one that you get by using the command $ cat /proc/cpuinfo | grep processor | wc -l)