Ralph, John, Prentice Thank you for your replies.
Indeed, —bind-to none or —bind-to socket solved my problem… mpirun —bind-to socket -host node1,node2 -x OMP_NUM_THREADS=4 -np 2 xhpl … happily runs 2 xhpl process, one on each node, with 4 cores fully utilised. The hints about top/htop/pstree/lstopo were/are also very helpful. Kind regards
