[Users] optimal nodes, mpi tasks, and cpus per mpi task?

[Bill Gabella]

Okay just a little advice from the community, running a qc0 BBH merger 
example on our HPC at Vanderbilt and trying to tune my parameters.  WE 
use Slurm / SBATCH and the ones I am working with are:

o amount of memory per node

o number of nodes

o numpy of MPI tasks

o if more than one cpu per task helps

One example was 4 GB per node, 4 nodes, 4 MPI tasks, and 2 CPUs per 
task.  Was a little slower than 1 CPU per task---perhaps memory.  I have 
learned from you all that ETK is a memory hog more than a CPU hog, ur, 
to say lots of memory helps vs lots of cores.

Any examples you have of simple, vanilla BBH would be good.  My SBATCH 
script includes

#SBATCH --mem 4000         # amount of memory per node
#SBATCH --nodes=4         # Like -24, number of nodes on which to run
#SBATCH -n 4              # Total number of mpi tasks requested, def 1 
task/1 cpu
#SBATCH -c 2              # Number of cpus per mpi task
#SBATCH -t 1:00:00         # Run time (d-hh:mm:ss)

and was told to use srun and not mpirun -np XXXX,


myparFile="qc0-mclachlan.par"
myCactusExe="/labs/einstein/20191028/Cactus/exe/cactus_sim"

##echo "mpirun -np 4 $myCactusExe $myparFile"
##mpirun -np 4 $myCactusExe $myparFile
echo "srun $myCactusExe $myparFile"
srun $myCactusExe $myparFile

Eventually I want to get Simfactory running and see several HPC's that 
use Slurm in the machine database directory.  Still I think I need to 
understand these parameters to tune the scripts Simfactory uses.

thanks, bill e.g.

-- 
=====================================
William Gabella
Research Assistant Professor
Department of Physics and Astronomy
Vanderbilt University
Nashville, TN  USA

b.gabella at vanderbilt.edu
(o) 615-343-2713