[OMPI users] binding to core odd results

Hi, In the process of testing out reframe I ran IMB pingpong using openmpi 3.1.0 with: mpirun -np 2 --report-bindings IMB-MPI1 pingpong I find that if set OMPI_MCA_hwloc_base_binding_policy=core I get slightly higher zero-size latency (1.58us vs 1.

[OMPI users] problems with scattering the ranks over all compute nodes using MPI spawning

Dear openmpi developers, I'm wondering how to scatter the ranks across all compute nodes when they are spawned by a master processor. I'm working on a cluster where Each node has two sockets, each socket is populated with a 16-core Haswell processor. Each core supports 2 hyper-threads. Whenever