PRRTE supports several levels of user-specified hostfiles based on an established precedence order. Users can specify a hostfile that contains a list of nodes to be used for the job, or can provide a comma-delimited list of nodes to be used for that job via the --host command line option.

The precedence order applied to these various options depends to some extent on the local environment. The following table illustrates how host and hostfile directives work together to define the set of hosts upon which a DVM will execute the job in the absence of a resource manager (RM):

host

hostfile

Result

unset

unset

The DVM will utilize all its available resources
when mapping the job.

set

unset

Host option defines resource list for the job

unset

set

Hostfile defines resource list for the job

set

set

Hostfile defines resource list for the job,
then host filters the list to define the final
set of nodes to be used for the job