CODEWITHSUNDEEP
mpislurm
Vaidyanathan
Vaidyanathan

Reputation: 399

SBATCH -n and srun -np

In the sbatch script below, does "np" (48) take precedence over "ntasks" or only 24 tasks are used to run. In other words, what happens when "np" is greater than "ntasks" or "np" is equal to "ntasks * N"

#SBATCH --ntasks 24
#SBATCH -N 2
mpirun -np 48 ./run

Upvotes: 0

Views: 333

Answers (1)

Victor Eijkhout
Victor Eijkhout

Reputation: 5810

Print out the slurm environment variables. You'll see that the hostlist is 24 items long, so if you create 48 processes, it will use each location in the hostlist twice. Depending on your core count that may lead to a loss of efficiency: all process run at the same time, but if you have more processes than cores, Unix will time-slice them.

Upvotes: 1

Related Questions