Q-Logic IB6054601-00 D manual Mpihosts File

Q

3 – Using InfiniPath MPI InfiniPath MPI Details

program-namewill generally be the pathname to the executable MPI program. If the MPI program resides in the current directory and the current directory is not in your search path, then program-namemust begin with ‘./’, such as:

./program-name

Unless you want to run only one instance of the program, you need to use the -npoption, as in:

$ mpirun -npn [other options] program-name

This spawns n instances of program-name.We usually call these instances node programs.

Each node program is started as a process on one node. While it is certainly possible for a node program to fork child processes, the children must not themselves call MPI functions.

mpirun monitors the parallel MPI job, terminating when all the node programs in that job exit normally, or if any of them terminates abnormally.

Killing the mpirun program kills all the processes in the job. Use Ctrl-Cto do this.

3.5.6

The mpihosts File

As noted in section 3.3 you have created an mpihosts file (also called a machines file, node file, or hosts file) in your current working directory. This file names the nodes on which the node programs may run. The mpihosts file contains lines of the form:

hostname[:p]

The optional part :p specifies the number of node programs that can be spawned on that node. When not specified, the default value is 1. The two supported formats for the mpihosts file are:

hostname1

hostname2

...

or

hostname1:process_count hostname2:process_count

...

In the first format, if the -np count is greater than the number of lines in the machine file, the hostnames will be repeated (in order) as many times as necessary for the requested number of node programs.

In the second format process_count can be different for each host, and is normally the number of available processors on the node. Up to process_count node

IB6054601-00 D 3-11