If you are running with multiple processes per node, then pass "--bind-to core:6" or "--bind-to hwthread:6" if you have more than one hardware thread per core and you want to map them to OpenMP threads. If your intention is to have only one MPI process per node, then make sure it is the case (e.g., by checking the hostname of each process). Also, I don't understand what you mean by virtual threads, but if you meant over-subscribing the same hardware thread with multiple OpenMP threads, then make sure you have at least 6 hardware threads available for each MPI process and use OpenMP CPU affinity hints (OMP_PROC_BIND for OpenMP >= 4, or GOMP_CPU_AFFINIty/KMP_AFFINITY depending on your compiler). Halim www.mcs.anl.gov/~aamer On 8/14/17 12:14 PM, Pasha Pashaei wrote:

Dear Colleague Hi I am working on hybrid MPI -OpenMp code and face with a problem. I can not run the code as the way that I want. I can run pure mpi code and also pure openmp code, but not hybrid one. I used "export OMP_NUM_THREADS=6" and then "mpirun -np 4 ./hybrid.exe > output.txt" It run but I noticed that It used only virtual threads of CPUs not physical threads. I have both OpenMpi and Mpich on my computer. My problem is I want to use mpi for communication between nodes and sockets and Openmp for cores which are inside of sockets and nodes, I do not know how to pin cpu to each other in each socket and nodes. I could find some material on internet such as https://aciref.org/how-to-gain-hybrid-mpi-openmp-code-performance-without-ch... How to gain hybrid MPI-OpenMP code performance without ...<https://aciref.org/how-to-gain-hybrid-mpi-openmp-code-performance-without-changing-a-line-of-code-a-k-a-dealing-with-task-affinity/> aciref.org How to gain hybrid MPI-OpenMP code performance without changing a line of code a.k.a. dealing with task affinity But it did not work, I think I need a PBS file to assign those commands on my grid with qsub command. If you need more information please let me know. I am looking forward to hearing from you, Best regards.

Pasha Pashaei

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