No, but it certainly makes life easier if you do. Simply stated, Open MPI can run on a group of servers or workstations connected by a network. As mentioned above, there are several prerequisites, however for example, you typically must have an account on all the machines, you can rsh or ssh between the nodes without using a password, etc. How to do this may be highly dependent upon your local configuration, so you may need to consult with your local system administrator. Some system administrators take care of these details for you, some don't.
Some common examples are included below, however. If 1 is not configured properly, executables like mpicc will not be found, and it is typically obvious what is wrong. This latter approach is preferred.
Consult the manual page for your shell for specific details some shells are picky about the permissions of the startup file, for example. Note that some Linux distributions automatically come with. Consult the bash man page for more information. If 2 is not configured properly, executables like mpirun will not function properly, and it can be somewhat confusing to figure out particularly for bash users. The startup files in question here are the ones that are automatically executed for a non-interactive login on a remote node e.
Note that not all shells support this, and that some shells use different files for this than listed in 1. Some shells will supersede 2 with 1. That is, fulfilling 2 may automatically fulfill 1.
The following table lists some common shells and the startup file that is automatically executed, either by Open MPI or by the shell itself: Shell Non-interactive login startup file sh Bourne or bash named " sh " This shell does not execute any file automatically, so Open MPI will execute the. Another case is where you want a single user to be able to launch multiple MPI jobs simultaneously, each with a different MPI implementation. Hence, setting shell startup files to point to one MPI implementation would be problematic.
In such cases, you have two options: Use mpirun 's --prefix command line option described below. Modify the wrapper compilers to include directives to include run-time search locations for the Open MPI libraries see this FAQ entry mpirun 's --prefix command line option takes as an argument the top-level directory where Open MPI was installed.
While relative directory names are possible, they can become ambiguous depending on the job launcher used; using absolute directory names is strongly recommended. This is usually unnecessary when using resource managers to launch jobs e. The --prefix option is therefore usually most useful in rsh or ssh -based environments or similar.
Beginning with the 1. Finally, note that specifying the absolute pathname to mpirun is equivalent to using the --prefix argument. Several of the questions in this FAQ category deal with using these commands. Note, however, that these commands are exactly identical. As such, the rest of this FAQ usually refers only to mpirun , even though the same discussions also apply to mpiexec and orterun because they are all, in fact, the same command.
Open MPI provides both mpirun and mpiexec commands. More information about the --hostfile option, and hostfiles in general, is available in this FAQ entry.
Note, however, that not all environments require a hostfile. Also note that if using a launcher that requires a hostfile and no hostfile is specified, all processes are launched on the local host. Both the mpirun and mpiexec commands support multiple program, multiple data MPMD style launches, either from the command line or from a file.
The first sub-application is the 2 a. Note that mpirun and mpiexec are identical in command-line options and behavior; using the above command lines with mpiexec instead of mpirun will result in the same behavior. There are three general mechanisms: The --hostfile option to mpirun. Use this option to specify a list of hosts on which to run. Note that for compatibility with other MPI implementations, --machinefile is a synonym for --hostfile.
See this FAQ entry for more information about the --hostfile option. The --host option to mpirun can be used to specify a list of hosts on which to run on the command line. See this FAQ entry for more information about the --host option.
If you are running in a scheduled environment e. NOTE: The specification of hosts using any of the above methods has nothing to do with the network interfaces that are used for MPI traffic.
The list of hosts is only used for specifying which hosts on which to launch MPI processes. You should probably also see this FAQ entry, too. However, Open MPI's wrapper compilers do not encode the Open MPI library locations in MPI executables by default the wrappers only specify a bare minimum of flags necessary to create MPI executables; we consider any flags beyond this bare minimum set a local policy decision.
In addition to what is mentioned in this FAQ entry , when you are able to run MPI jobs on a single host, but fail to run them across multiple hosts, try the following: Ensure that your launcher is able to launch across multiple hosts.
For example, if you are using ssh , try to ssh to each remote host and ensure that you are not prompted for a password. Or, if you are running in a managed environment, such as in a Slurm, Torque, or other job launcher, check that you have reserved enough hosts, are running in an allocated job, etc.
LD library path on the remote host Run a simple, non-MPI job across multiple hosts. This verifies that the Open MPI run-time system is functioning properly across multiple hosts. This verifies that the MPI subsystem is able to initialize and terminate properly. Double check your non-interactive login setup on remote hosts. This particular library, libimf. As such, it is likely that the user did not setup the Intel compiler library in their environment properly on this node. Double check that you have setup the Intel compiler environment on the target node, for both interactive and non-interactive logins.
It is a common error to ensure that the Intel compiler environment is setup properly for interactive logins, but not for non-interactive logins. Check your shell script startup files and verify that the Intel compiler environment is setup properly for non-interactive logins.
This particular library, libpgc. As such, it is likely that the user did not setup the PGI compiler library in their environment properly on this node.
Double check that you have setup the PGI compiler environment on the target node, for both interactive and non-interactive logins.
It is a common error to ensure that the PGI compiler environment is setup properly for interactive logins, but not for non-interactive logins. Check your shell script startup files and verify that the PGI compiler environment is setup properly for non-interactive logins. Jump to: navigation , search. Basics This page will give you a general overview of how to compile and execute a program that has been parallelized with MPI.
Category : HPC-User. Navigation menu Personal tools Log in. Namespaces Page Discussion. Views Read View source View history. This page was last edited on 12 June , at As an example, consider a node with two processor sockets, each comprising four cores.
In the first case, the processes bind to successive cores as indicated by the masks , , , and In the second case, processes bind to all cores on successive sockets as indicated by the masks f and 00f0.
The processes cycle through the processor sockets in a round-robin fashion as many times as are needed. In the third case, the masks show us that 2 cores have been bound per process. In the fourth case, binding is turned off and no bindings are reported. Therefore, certain process binding options may not be available on every system. Process binding can also be set with MCA parameters.
Their usage is less convenient than that of mpirun options. On the other hand, MCA parameters can be set not only on the mpirun command line, but alternatively in a system or user mca-params. Rank 1 runs on node bb, bound to logical socket 0, cores 0 and 1. Rank 2 runs on node cc, bound to logical cores 1 and 2. Rankfiles can alternatively be used to specify physical processor locations. In this case, the syntax is somewhat different. The hostnames listed above are "absolute," meaning that actual resolveable hostnames are specified.
However, hostnames can also be specified as "relative," meaning that they are specified in relation to an externally-specified list of hostnames e. Application Context or Executable Program? To distinguish the two different forms, mpirun looks on the command line for --app option. If it is specified, then the file named on the command line is assumed to be an application context.
If it is not specified, then the file is assumed to be an executable program. Locating Files If no relative or absolute path is specified for a file, Open MPI will first look for files by searching the directories specified by the --path option. If a relative directory is specified, it must be relative to the initial working directory determined by the specific starter used.
Other starters may set the initial directory to the current working directory from the invocation of mpirun.
Current Working Directory The -wdir mpirun option and its synonym, -wd allows the user to change to an arbitrary directory before the program is invoked. If the -wdir option appears both in a context file and on the command line, the context file directory will override the command line value.
If the -wdir option is specified, Open MPI will attempt to change to the specified directory on all of the remote nodes. If this fails, mpirun will abort. If the -wdir option is not specified, Open MPI will send the directory name where mpirun was invoked to each of the remote nodes. The remote nodes will try to change to that directory.
If they are unable e. Other signals are not currently propagated by orterun. Since mpirun will notice that the process died due to a signal, it is probably not necessary and safest for the user to only clean up non-MPI state. On remote nodes, the exact environment is determined by the boot MCA module used.
See the "Remote Execution" section for more details. The --prefix option is provided for some simple configurations where this is not possible. The --prefix option takes a single argument: the base directory on the remote node where Open MPI is installed.
The --prefix option is not sufficient if the installation paths on the remote node are different than the local node e. Note that executing mpirun via an absolute pathname is equivalent to specifying --prefix without the last subdirectory in the absolute pathname to mpirun. The -x option to mpirun has been deprecated, but the syntax of the MCA param follows that prior example.
While the syntax of the -x option and MCA param allows the definition of new variables, note that the parser for these options are currently not very sophisticated - it does not even understand quoted values. Users are advised to set variables in the environment and use the option to export them; not to define them. MCA modules have direct impact on MPI programs because they allow tunable parameters to be set at run time such as which BTL communication device driver to use, what parameters to pass to that BTL, etc.
Note that the -mca switch is simply a shortcut for setting environment variables. The same effect may be accomplished by setting corresponding environment variables before running mpirun. Setting MCA parameters and environment variables from file. This option requires a single file or list of files separated by "," to follow. If any argument is duplicated in the file, the last value read will be used. MCA parameters and environment specified on the command line have higher precedence than variables specified in the file.
MPI applications should be run as regular non-root users. Reflecting this advice, mpirun will refuse to run as root by default. To override this default, you can add the --allow-run-as-root option to the mpirun command line. Exit status There is no standard definition for what mpirun should return as an exit status. Any non-zero exit status in secondary jobs will be reported solely in a summary print statement.
This is generally not considered an "abnormal termination" - i. Instead, the default behavior simply reports the number of processes terminating with non-zero status upon completion of the job.
However, in some cases it can be desirable to have the job abort when any process terminates with non-zero status. It is not anticipated that this situation will occur frequently.
However, in the interest of serving the broader community, OMPI now has a means for allowing users to direct that jobs be aborted upon any process exiting with non-zero status.
Terminations caused in this manner will be reported on the console as an "abnormal termination", with the first process to so exit identified along with its exit status. Examples Be sure also to see the examples throughout the sections above. If an internal error occurred in mpirun, the corresponding error code is returned. Note that, in general, this will be the first process that died but is not guaranteed to be so. If the --timeout command line option is used and the timeout expires before the job completes thereby forcing mpirun to kill the job mpirun will return an exit status equivalent to the value of ETIMEDOUT which is typically on Linux and OS X systems.
Rankfiles Application Context or Executable Program?
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