Jim, You can
mpirun --use-hwthread-cpus ... to have one slot = one hyperthread (default is slot = core) Note you always have the opportunity to mpirun --oversubscribe ... Cheers, Gilles ----- Original Message ----- I've just compiled my own version of ompi on Ubuntu 20.04 linux for use with R and Rmpi etc. It works ok but the maximum number of slaves I can get is number of cores (20). I used to be able to get the number of hyperthreaded slots (40). What is the most likely cause of my new problem and/or how can I fix it? I configured ompi 4.03 with this statement. $ ./configure --disable-dlopen Thx. J -- Jim Maas
