In our slurm configuration both cores and memory are consumable resources, meaning that slurm keeps track of how many cores and how much memory has been allocated to jobs on each node. A node is considered full if either all the cores are allocated, or all the memory is allocated.

By default, each job is allocated 1 core and 8GB of memory per core (so 8GB total since the default is 1 core).

You can change your allocation from the default using the -c = –cpus-per-task, –exclusive, –mem, and –mem-per-cpu options.

If you use the “–exclusive” flag, slurm will allocate all cores on one node to your job, but unless otherwise specified it will still allocate the default of 8GB per core. This may not be all the memory available on the node that slurm allocates to you (e.g. on a node with 32 cores and 384GB of RAM, slurm would allocate 256GB of that RAM to your job). So, if you want a whole node you should probably use both “–exclusive” and “–mem=0” (which slurm treats as a request for all memory on a node).

In the man pages, generally, CPU==core because of this configuration choice. For example, the -c option mentioned above has full name –cpus-per-task but really means cores per task in our configuration.