Host syntax consists of a comma-delimited list of node names, each
entry optionally containing a :N
extension indicating the number
of slots to assign to that entry:
--host node01:5,node02
In the absence of the slot extension, one slot will be assigned to the node. Duplicate entries are aggregated and the number of slots assigned to that node are summed together.
Note
A “slot” is the PRRTE term for an allocatable unit where we can launch a process. Thus, the number of slots equates to the maximum number of processes PRRTE may start on that node without oversubscribing it.