CINECA slurm update to 22.05.8 version - IMPORTANT NOTE for hybrid runs

Dear Users,

as announced at the end of Marconi maintenance on February 14, we updated the slurm scheduler to version 22.05.8; please, find the release notes at the link

https://slurm.schedmd.com/news.html

Please note a major modification, reported in the Highlights of the release notes:

srun will no longer read in SLURM_CPUS_PER_TASK. This means you will explicitly have to 
specify --cpus-per-task on your srun calls, or set the new SRUN_CPUS_PER_TASK env var 
to accomplish the same thing.

Such modification affects hybrid (MPI/OpenMP) jobs launched with srun, since the consequent mapping of the multithreaded tasks will result in an overallocation of the cpus. As reported in the slurm Highlights, you can

• define the SRUN_CPUS_PER_TASK env var in your scripts:

export SRUN_CPUS_PER_TASK=$SLURM_CPUS_PER_TASK
srun your_exe

• or your can repeat the --cpus-per-task directive as option of srun:

srun --cpus-per-task=$SLURM_CPUS_PER_TASK your_exe

Best regards,

HPC User Support @ CINECA