On Sun, 19 Jun 2016 09:15:34 -0700 Achi Hamza <h16m...@gmail.com> wrote:
> Hi everyone, > > I set a lab consists of 5 simple nodes (1 head and 4 compute nodes), > i used SLURM 15.08.11, OpenMpi 1.10.2, MPICH 3.2, FFTW 3.3.4 and > LAMMPS 16May2016. Did you use OpenMPI _or_ MPICH? Two observations on the below behavior: * a 17 second runtime could indicate a very small problem that doesn't scale past a few ranks. * Your mpi launch could screw up the placement/pinning of ranks /Peter K > After successful installation of the above i conducted some tests > using the existing examples of LAMMPS. I got unrealistic results, the > time execution goes up as i increase the number of nodes ! > > mpirun -np 4 lmp_openmpi < in.vacf.2d > *Total wall time: 0:00:17* > > mpirun -np 8 lmp_openmpi < in.vacf.2d > *Total wall time: 0:00:23* > > mpirun -np 12 lmp_openmpi < in.vacf.2d > *Total wall time: 0:00:28* > > mpirun -np 16 lmp_openmpi < in.vacf.2d > *Total wall time: 0:00:33* > > > interestingly, *srun* results are worse than mpirun: > > srun --mpi=pmi2 -n 16 lmp_openmpi < in.vacf.2d > > *Total wall time: 0:05:54*
