MPIRUN(1)                          Open MPI                          MPIRUN(1)



NAME
       orterun, mpirun, mpiexec - Execute serial and parallel jobs in Open
       MPI.

       Note: mpirun, mpiexec, and orterun are all synonyms for each other.
       Using any of the names will produce the same behavior.

SYNOPSIS
       Single Process Multiple Data (SPMD) Model:

       mpirun [ options ] <program> [ <args> ]

       Multiple Instruction Multiple Data (MIMD) Model:

       mpirun [ global_options ]
              [ local_options1 ] <program1> [ <args1> ] :
              [ local_options2 ] <program2> [ <args2> ] :
              ... :
              [ local_optionsN ] <programN> [ <argsN> ]

       Note that in both models, invoking mpirun via an absolute path name is
       equivalent to specifying the --prefix option with a <dir> value
       equivalent to the directory where mpirun resides, minus its last
       subdirectory.  For example:

           % /usr/local/bin/mpirun ...

       is equivalent to

           % mpirun --prefix /usr/local


QUICK SUMMARY
       If you are simply looking for how to run an MPI application, you
       probably want to use a command line of the following form:

           % mpirun [ -np X ] [ --hostfile <filename> ]  <program>

       This will run X copies of <program> in your current run-time
       environment (if running under a supported resource manager, Open MPI's
       mpirun will usually automatically use the corresponding resource
       manager process starter, as opposed to, for example, rsh or ssh, which
       require the use of a hostfile, or will default to running all X copies
       on the localhost), scheduling (by default) in a round-robin fashion by
       CPU slot.  See the rest of this page for more details.

OPTIONS
       mpirun will send the name of the directory where it was invoked on the
       local node to each of the remote nodes, and attempt to change to that
       directory.  See the "Current Working Directory" section below for
       further details.

       <program> The program executable. This is identified as the first non-
                 recognized argument to mpirun.

       <args>    Pass these run-time arguments to every new process.  These
                 must always be the last arguments to mpirun. If an app
                 context file is used, <args> will be ignored.

       -h, --help
                 Display help for this command

       -q, --quiet
                 Suppress informative messages from orterun during application
                 execution.

       -v, --verbose
                 Be verbose

       -V, --version
                 Print version number.  If no other arguments are given, this
                 will also cause orterun to exit.

       To specify which hosts (nodes) of the cluster to run on:

       -H, -host, --host <host1,host2,...,hostN>
              List of hosts on which to invoke processes.

       -hostfile, --hostfile <hostfile>
              Provide a hostfile to use.

       -machinefile, --machinefile <machinefile>
              Synonym for -hostfile.

       To specify the number of processes to launch:

       -c, -n, --n, -np <#>
              Run this many copies of the program on the given nodes.  This
              option indicates that the specified file is an executable
              program and not an application context. If no value is provided
              for the number of copies to execute (i.e., neither the "-np" nor
              its synonyms are provided on the command line), Open MPI will
              automatically execute a copy of the program on each process slot
              (see below for description of a "process slot"). This feature,
              however, can only be used in the SPMD model and will return an
              error (without beginning execution of the application)
              otherwise.

       -npersocket, --npersocket <#persocket>
              On each node, launch this many processes times the number of
              processor sockets on the node.  The -npersocket option also
              turns on the -bind-to-socket option.

       -npernode, --npernode <#pernode>
              On each node, launch this many processes.

       -pernode, --pernode
              On each node, launch one process -- equivalent to -npernode 1.

       To map processes to nodes:

       -loadbalance, --loadbalance
              Uniform distribution of ranks across all nodes. See more
              detailed description below.

       -nolocal, --nolocal
              Do not run any copies of the launched application on the same
              node as orterun is running.  This option will override listing
              the localhost with --host or any other host-specifying
              mechanism.

       -nooversubscribe, --nooversubscribe
              Do not oversubscribe any nodes; error (without starting any
              processes) if the requested number of processes would cause
              oversubscription.  This option implicitly sets "max_slots" equal
              to the "slots" value for each node.

       -bynode, --bynode
              Launch processes one per node, cycling by node in a round-robin
              fashion.  This spreads processes evenly among nodes and assigns
              ranks in a round-robin, "by node" manner.

       For process binding:

       -bycore, --bycore
              Associate processes with successive cores if used with one of
              the -bind-to-* options.

       -bysocket, --bysocket
              Associate processes with successive processor sockets if used
              with one of the -bind-to-* options.

       -cpus-per-proc, --cpus-per-proc <#perproc>
              Use the number of cores per process if used with one of the
              -bind-to-* options.

       -cpus-per-rank, --cpus-per-rank <#perrank>
              Alias for -cpus-per-proc.

       -bind-to-core, --bind-to-core
              Bind processes to cores.

       -bind-to-socket, --bind-to-socket
              Bind processes to processor sockets.

       -bind-to-none, --bind-to-none
              Do not bind processes.  (Default.)

       -report-bindings, --report-bindings
              Report any bindings for launched processes.

       -slot-list, --slot-list <slots>
              List of processor IDs to be used for binding MPI processes. The
              specified bindings will be applied to all MPI processes. See
              explanation below for syntax.

       For rankfiles:

       -rf, --rankfile <rankfile>
              Provide a rankfile file.

       To manage standard I/O:

       -output-filename, --output-filename <filename>
              Redirect the stdout, stderr, and stddiag of all ranks to a rank-
              unique version of the specified filename. Any directories in the
              filename will automatically be created.  Each output file will
              consist of filename.rank, where the rank will be left-filled
              with zero's for correct ordering in listings.

       -stdin, --stdin <rank>
              The MPI rank that is to receive stdin. The default is to forward
              stdin to rank=0, but this option can be used to forward stdin to
              any rank. It is also acceptable to specify none, indicating that
              no ranks are to receive stdin.

       -tag-output, --tag-output
              Tag each line of output to stdout, stderr, and stddiag with
              [jobid, rank]<stdxxx> indicating the process jobid and rank that
              generated the output, and the channel which generated it.

       -timestamp-output, --timestamp-output
              Timestamp each line of output to stdout, stderr, and stddiag.

       -xml, --xml
              Provide all output to stdout, stderr, and stddiag in an xml
              format.

       -xterm, --xterm <ranks>
              Display the specified ranks in separate xterm windows. The ranks
              are specified as a comma-separated list of ranges, with a -1
              indicating all. A separate window will be created for each
              specified rank.  Note: In some environments, xterm may require
              that the executable be in the user's path, or be specified in
              absolute or relative terms. Thus, it may be necessary to specify
              a local executable as "./foo" instead of just "foo". If xterm
              fails to find the executable, mpirun will hang, but still
              respond correctly to a ctrl-c.  If this happens, please check
              that the executable is being specified correctly and try again.

       To manage files and runtime environment:

       -path, --path <path>
              <path> that will be used when attempting to locate the requested
              executables.  This is used prior to using the local PATH
              setting.

       --prefix <dir>
              Prefix directory that will be used to set the PATH and
              LD_LIBRARY_PATH on the remote node before invoking Open MPI or
              the target process.  See the "Remote Execution" section, below.

       --preload-binary
              Copy the specified executable(s) to remote machines prior to
              starting remote processes. The executables will be copied to the
              Open MPI session directory and will be deleted upon completion
              of the job.

       --preload-files <files>
              Preload the comma separated list of files to the current working
              directory of the remote machines where processes will be
              launched prior to starting those processes.

       --preload-files-dest-dir <path>
              The destination directory to be used for preload-files, if other
              than the current working directory. By default, the absolute and
              relative paths provided by --preload-files are used.

       --tmpdir <dir>
              Set the root for the session directory tree for mpirun only.

       -wd <dir>
              Synonym for -wdir.

       -wdir <dir>
              Change to the directory <dir> before the user's program
              executes.  See the "Current Working Directory" section for notes
              on relative paths.  Note: If the -wdir option appears both on
              the command line and in an application context, the context will
              take precedence over the command line.

       -x <env>
              Export the specified environment variables to the remote nodes
              before executing the program.  Only one environment variable can
              be specified per -x option.  Existing environment variables can
              be specified or new variable names specified with corresponding
              values.  For example:
                  % mpirun -x DISPLAY -x OFILE=/tmp/out ...

              The parser for the -x option is not very sophisticated; it does
              not even understand quoted values.  Users are advised to set
              variables in the environment, and then use -x to export (not
              define) them.

       Setting MCA parameters:

       -gmca, --gmca <key> <value>
              Pass global MCA parameters that are applicable to all contexts.
              <key> is the parameter name; <value> is the parameter value.

       -mca, --mca <key> <value>
              Send arguments to various MCA modules.  See the "MCA" section,
              below.

       For debugging:

       -debug, --debug
              Invoke the user-level debugger indicated by the
              orte_base_user_debugger MCA parameter.

       -debugger, --debugger
              Sequence of debuggers to search for when --debug is used (i.e.
              a synonym for orte_base_user_debugger MCA parameter).

       -tv, --tv
              Launch processes under the TotalView debugger.  Deprecated
              backwards compatibility flag. Synonym for --debug.

       There are also other options:

       -aborted, --aborted <#>
              Set the maximum number of aborted processes to display.

       --app <appfile>
              Provide an appfile, ignoring all other command line options.

       -cf, --cartofile <cartofile>
              Provide a cartography file.

       --hetero
              Indicates that multiple app_contexts are being provided that are
              a mix of 32/64-bit binaries.

       -leave-session-attached, --leave-session-attached
              Do not detach OmpiRTE daemons used by this application. This
              allows error messages from the daemons as well as the underlying
              environment (e.g., when failing to launch a daemon) to be
              output.

       -ompi-server, --ompi-server <uri or file>
              Specify the URI of the Open MPI server, or the name of the file
              (specified as file:filename) that contains that info. The Open
              MPI server is used to support multi-application data exchange
              via the MPI-2 MPI_Publish_name and MPI_Lookup_name functions.

       -wait-for-server, --wait-for-server
              Pause mpirun before launching the job until ompi-server is
              detected. This is useful in scripts where ompi-server may be
              started in the background, followed immediately by an mpirun
              command that wishes to connect to it. Mpirun will pause until
              either the specified ompi-server is contacted or the server-
              wait-time is exceeded.

       -server-wait-time, --server-wait-time <secs>
              The max amount of time (in seconds) mpirun should wait for the
              ompi-server to start. The default is 10 seconds.

       The following options are useful for developers; they are not generally
       useful to most ORTE and/or MPI users:

       -d, --debug-devel
              Enable debugging of the OmpiRTE (the run-time layer in Open
              MPI).  This is not generally useful for most users.

       --debug-daemons
              Enable debugging of any OmpiRTE daemons used by this
              application.

       --debug-daemons-file
              Enable debugging of any OmpiRTE daemons used by this
              application, storing output in files.

       -launch-agent, --launch-agent
              Name of the executable that is to be used to start processes on
              the remote nodes. The default is "orted". This option can be
              used to test new daemon concepts, or to pass options back to the
              daemons without having mpirun itself see them. For example,
              specifying a launch agent of orted -mca odls_base_verbose 5
              allows the developer to ask the orted for debugging output
              without clutter from mpirun itself.

       --noprefix
              Disable the automatic --prefix behavior

       There may be other options listed with mpirun --help.

DESCRIPTION
       One invocation of mpirun starts an MPI application running under Open
       MPI. If the application is single process multiple data (SPMD), the
       application can be specified on the mpirun command line.

       If the application is multiple instruction multiple data (MIMD),
       comprising of multiple programs, the set of programs and argument can
       be specified in one of two ways: Extended Command Line Arguments, and
       Application Context.

       An application context describes the MIMD program set including all
       arguments in a separate file.  This file essentially contains multiple
       mpirun command lines, less the command name itself.  The ability to
       specify different options for different instantiations of a program is
       another reason to use an application context.

       Extended command line arguments allow for the description of the
       application layout on the command line using colons (:) to separate the
       specification of programs and arguments. Some options are globally set
       across all specified programs (e.g. --hostfile), while others are
       specific to a single program (e.g. -np).

   Specifying Host Nodes
       Host nodes can be identified on the mpirun command line with the -host
       option or in a hostfile.

       For example,

       mpirun -H aa,aa,bb ./a.out
           launches two processes on node aa and one on bb.

       Or, consider the hostfile

          % cat myhostfile
          aa slots=2
          bb slots=2
          cc slots=2


       Here, we list both the host names (aa, bb, and cc) but also how many
       "slots" there are for each.  Slots indicate how many processes can
       potentially execute on a node.  For best performance, the number of
       slots may be chosen to be the number of cores on the node or the number
       of processor sockets.  If the hostfile does not provide slots
       information, a default of 1 is assumed.  When running under resource
       managers (e.g., SLURM, Torque, etc.), Open MPI will obtain both the
       hostnames and the number of slots directly from the resource manger.

       mpirun -hostfile myhostfile ./a.out
           will launch two processes on each of the three nodes.

       mpirun -hostfile myhostfile -host aa ./a.out
           will launch two processes, both on node aa.

       mpirun -hostfile myhostfile -host dd ./a.out
           will find no hosts to run on and abort with an error.  That is, the
           specified host dd is not in the specified hostfile.

   Specifying Number of Processes
       As we have just seen, the number of processes to run can be set using
       the hostfile.  Other mechanisms exist.

       The number of processes launched can be specified as a multiple of the
       number of nodes or processor sockets available.  For example,

       mpirun -H aa,bb -npersocket 2 ./a.out
           launches processes 0-3 on node aa and process 4-7 on node bb, where
           aa and bb are both dual-socket nodes.  The -npersocket option also
           turns on the -bind-to-socket option, which is discussed in a later
           section.

       mpirun -H aa,bb -npernode 2 ./a.out
           launches processes 0-1 on node aa and processes 2-3 on node bb.

       mpirun -H aa,bb -npernode 1 ./a.out
           launches one process per host node.

       mpirun -H aa,bb -pernode ./a.out
           is the same as -npernode 1.

       Another alternative is to specify the number of processes with the -np
       option.  Consider now the hostfile

          % cat myhostfile
          aa slots=4
          bb slots=4
          cc slots=4


       Now,

       mpirun -hostfile myhostfile -np 6 ./a.out
           will launch ranks 0-3 on node aa and ranks 4-5 on node bb.  The
           remaining slots in the hostfile will not be used since the -np
           option indicated that only 6 processes should be launched.

   Mapping Processes to Nodes
       The examples above illustrate the default mapping of process ranks to
       nodes.  This mapping can also be controlled with various mpirun
       options.  Here, we consider the same hostfile as above with -np 6
       again:

                                 node aa      node bb      node cc

         mpirun                  0 1 2 3      4 5

         mpirun -loadbalance     0 1          2 3          4 5

         mpirun -bynode          0 3          1 4          2 5

         mpirun -nolocal                      0 1 2 3      4 5

       The -loadbalance option tries to spread processes out fairly among the
       nodes.

       The -bynode option does likewise but numbers the processes in "by node"
       in a round-robin fashion.

       The -nolocal option prevents any processes from being mapped onto the
       local host (in this case node aa).  While mpirun typically consumes few
       system resources, -nolocal can be helpful for launching very large jobs
       where mpirun may actually need to use noticable amounts of memory
       and/or processing time.

       Just as -np can specify fewer processes than there are slots, it can
       also oversubscribe the slots.  For example, with the same hostfile:

       mpirun -hostfile myhostfile -np 14 ./a.out
           will launch processes 0-3 on node aa, 4-7 on bb, and 8-11 on cc.
           It will then add the remaining two processes to whichever nodes it
           chooses.

       One can also specify limits to oversubscription.  For example, with the
       same hostfile:

       mpirun -hostfile myhostfile -np 14 -nooversubscribe ./a.out
           will produce an error since -nooversubscribe prevents
           oversubscription.

       Limits to oversubscription can also be specified in the hostfile
       itself:
        % cat myhostfile
        aa slots=4 max_slots=4
        bb         max_slots=4
        cc slots=4

       The max_slots field specifies such a limit.  When it does, the slots
       value defaults to the limit.  Now:

       mpirun -hostfile myhostfile -np 14 ./a.out
           causes the first 12 processes to be launched as before, but the
           remaining two processes will be forced onto node cc.  The other two
           nodes are protected by the hostfile against oversubscription by
           this job.

       Using the --nooversubscribe option can be helpful since Open MPI
       currently does not get "max_slots" values from the resource manager.

       Of course, -np can also be used with the -H or -host option.  For
       example,

       mpirun -H aa,bb -np 8 ./a.out
           launches 8 processes.  Since only two hosts are specified, after
           the first two processes are mapped, one to aa and one to bb, the
           remaining processes oversubscribe the specified hosts.

       And here is a MIMD example:

       mpirun -H aa -np 1 hostname : -H bb,cc -np 2 uptime
           will launch process 0 running hostname on node aa and processes 1
           and 2 each running uptime on nodes bb and cc, respectively.

   Process Binding
       Processes may be bound to specific resources on a node.  This can
       improve performance if the operating system is placing processes
       suboptimally.  For example, it might oversubscribe some multi-core
       processor sockets, leaving other sockets idle;  this can lead processes
       to contend unnecessarily for common resources.  Or, it might spread
       processes out too widely;  this can be suboptimal if application
       performance is sensitive to interprocess communication costs.  Binding
       can also keep the operating system from migrating processes
       excessively, regardless of how optimally those processes were placed to
       begin with.

       To bind processes, one must first associate them with the resources on
       which they should run.  For example, the -bycore option associates the
       processes on a node with successive cores.  Or, -bysocket associates
       the processes with successive processor sockets, cycling through the
       sockets in a round-robin fashion if necessary.  And -cpus-per-proc
       indicates how many cores to bind per process.

       But, such association is meaningless unless the processes are actually
       bound to those resources.  The binding option specifies the granularity
       of binding -- say, with -bind-to-core or -bind-to-socket.  One can also
       turn binding off with -bind-to-none, which is typically the default.

       Finally, -report-bindings can be used to report bindings.

       As an example, consider a node with two processor sockets, each
       comprising four cores.  We run mpirun with -np 4 -report-bindings and
       the following additional options:

        % mpirun ... -bycore -bind-to-core
        [...] ... binding child [...,0] to cpus 0001
        [...] ... binding child [...,1] to cpus 0002
        [...] ... binding child [...,2] to cpus 0004
        [...] ... binding child [...,3] to cpus 0008

        % mpirun ... -bysocket -bind-to-socket
        [...] ... binding child [...,0] to socket 0 cpus 000f
        [...] ... binding child [...,1] to socket 1 cpus 00f0
        [...] ... binding child [...,2] to socket 0 cpus 000f
        [...] ... binding child [...,3] to socket 1 cpus 00f0

        % mpirun ... -cpus-per-proc 2 -bind-to-core
        [...] ... binding child [...,0] to cpus 0003
        [...] ... binding child [...,1] to cpus 000c
        [...] ... binding child [...,2] to cpus 0030
        [...] ... binding child [...,3] to cpus 00c0

        % mpirun ... -bind-to-none

       Here, -report-bindings shows the binding of each process as a mask.  In
       the first case, the processes bind to successive cores as indicated by
       the masks 0001, 0002, 0004, and 0008.  In the second case, processes
       bind to all cores on successive sockets as indicated by the masks 000f
       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 bind per process.  In the
       fourth case, binding is turned off and no bindings are reported.

       Open MPI's support for process binding depends on the underlying
       operating system.  Therefore, processing binding 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.conf file or as
       environment variables, as described in the MCA section below.  The
       correspondences are:

         mpirun option          MCA parameter key           value

         -bycore                rmaps_base_schedule_policy  core
         -bysocket              rmaps_base_schedule_policy  socket
         -bind-to-core          orte_process_binding        core
         -bind-to-socket        orte_process_binding        socket
         -bind-to-none          orte_process_binding        none

       The orte_process_binding value can also take on the :if-avail
       attribute.  This attribute means that processes will be bound only if
       this is supported on the underlying operating system.  Without the
       attribute, if there is no such support, the binding request results in
       an error.  For example, you could have

         % cat $HOME/.openmpi/mca-params.conf
         rmaps_base_schedule_policy = socket
         orte_process_binding       = socket:if-avail

   Rankfiles
       Rankfiles provide a means for specifying detailed information about how
       process ranks should be mapped to nodes and how they should be bound.
       Consider the following:

           cat myrankfile
           rank 0=aa slot=1:0-2
           rank 1=bb slot=0:0,1
           rank 2=cc slot=1-2
           mpirun -H aa,bb,cc,dd -rf myrankfile ./a.out So that

         Rank 0 runs on node aa, bound to socket 1, cores 0-2.
         Rank 1 runs on node bb, bound to socket 0, cores 0 and 1.
         Rank 2 runs on node cc, bound to cores 1 and 2.

   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 there is no --path option set or if the file is not
       found at the --path location, then Open MPI will search the user's PATH
       environment variable as defined on the source node(s).

       If a relative directory is specified, it must be relative to the
       initial working directory determined by the specific starter used. For
       example when using the rsh or ssh starters, the initial directory is
       $HOME by default. 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.  It can
       also be used in application context files to specify working
       directories on specific nodes and/or for specific applications.

       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.g.,
       if the directory does not exist on that node), then Open MPI will use
       the default directory determined by the starter.

       All directory changing occurs before the user's program is invoked; it
       does not wait until MPI_INIT is called.

   Standard I/O
       Open MPI directs UNIX standard input to /dev/null on all processes
       except the MPI_COMM_WORLD rank 0 process. The MPI_COMM_WORLD rank 0
       process inherits standard input from mpirun.  Note: The node that
       invoked mpirun need not be the same as the node where the
       MPI_COMM_WORLD rank 0 process resides. Open MPI handles the redirection
       of mpirun's standard input to the rank 0 process.

       Open MPI directs UNIX standard output and error from remote nodes to
       the node that invoked mpirun and prints it on the standard output/error
       of mpirun.  Local processes inherit the standard output/error of mpirun
       and transfer to it directly.

       Thus it is possible to redirect standard I/O for Open MPI applications
       by using the typical shell redirection procedure on mpirun.

             % mpirun -np 2 my_app < my_input > my_output

       Note that in this example only the MPI_COMM_WORLD rank 0 process will
       receive the stream from my_input on stdin.  The stdin on all the other
       nodes will be tied to /dev/null.  However, the stdout from all nodes
       will be collected into the my_output file.

   Signal Propagation
       When orterun receives a SIGTERM and SIGINT, it will attempt to kill the
       entire job by sending all processes in the job a SIGTERM, waiting a
       small number of seconds, then sending all processes in the job a
       SIGKILL.

       SIGUSR1 and SIGUSR2 signals received by orterun are propagated to all
       processes in the job.

       One can turn on forwarding of SIGSTOP and SIGCONT to the program
       executed by mpirun by setting the MCA parameter
       orte_forward_job_control to 1.  A SIGTSTOP signal to mpirun will then
       cause a SIGSTOP signal to be sent to all of the programs started by
       mpirun and likewise a SIGCONT signal to mpirun will cause a SIGCONT
       sent.

       Other signals are not currently propagated by orterun.

   Process Termination / Signal Handling
       During the run of an MPI application, if any rank dies abnormally
       (either exiting before invoking MPI_FINALIZE, or dying as the result of
       a signal), mpirun will print out an error message and kill the rest of
       the MPI application.

       User signal handlers should probably avoid trying to cleanup MPI state
       (Open MPI is, currently, neither thread-safe nor async-signal-safe).
       For example, if a segmentation fault occurs in MPI_SEND (perhaps
       because a bad buffer was passed in) and a user signal handler is
       invoked, if this user handler attempts to invoke MPI_FINALIZE, Bad
       Things could happen since Open MPI was already "in" MPI when the error
       occurred.  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.

   Process Environment
       Processes in the MPI application inherit their environment from the
       Open RTE daemon upon the node on which they are running.  The
       environment is typically inherited from the user's shell.  On remote
       nodes, the exact environment is determined by the boot MCA module used.
       The rsh launch module, for example, uses either rsh/ssh to launch the
       Open RTE daemon on remote nodes, and typically executes one or more of
       the user's shell-setup files before launching the Open RTE daemon.
       When running dynamically linked applications which require the
       LD_LIBRARY_PATH environment variable to be set, care must be taken to
       ensure that it is correctly set when booting Open MPI.

       See the "Remote Execution" section for more details.

   Remote Execution
       Open MPI requires that the PATH environment variable be set to find
       executables on remote nodes (this is typically only necessary in rsh-
       or ssh-based environments -- batch/scheduled environments typically
       copy the current environment to the execution of remote jobs, so if the
       current environment has PATH and/or LD_LIBRARY_PATH set properly, the
       remote nodes will also have it set properly).  If Open MPI was compiled
       with shared library support, it may also be necessary to have the
       LD_LIBRARY_PATH environment variable set on remote nodes as well
       (especially to find the shared libraries required to run user MPI
       applications).

       However, it is not always desirable or possible to edit shell startup
       files to set PATH and/or LD_LIBRARY_PATH.  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.  Open MPI will use this
       directory to set the remote PATH and LD_LIBRARY_PATH before executing
       any Open MPI or user applications.  This allows running Open MPI jobs
       without having pre-configured the PATH and LD_LIBRARY_PATH on the
       remote nodes.

       Open MPI adds the basename of the current node's "bindir" (the
       directory where Open MPI's executables are installed) to the prefix and
       uses that to set the PATH on the remote node.  Similarly, Open MPI adds
       the basename of the current node's "libdir" (the directory where Open
       MPI's libraries are installed) to the prefix and uses that to set the
       LD_LIBRARY_PATH on the remote node.  For example:

       Local bindir:  /local/node/directory/bin

       Local libdir:  /local/node/directory/lib64

       If the following command line is used:

           % mpirun --prefix /remote/node/directory

       Open MPI will add "/remote/node/directory/bin" to the PATH and
       "/remote/node/directory/lib64" to the D_LIBRARY_PATH on the remote node
       before attempting to execute anything.

       Note that --prefix can be set on a per-context basis, allowing for
       different values for different nodes.

       The --prefix option is not sufficient if the installation paths on the
       remote node are different than the local node (e.g., if "/lib" is used
       on the local node, but "/lib64" is used on the remote node), or if the
       installation paths are something other than a subdirectory under a
       common prefix.

       Note that executing mpirun via an absolute pathname is equivalent to
       specifying --prefix without the last subdirectory in the absolute
       pathname to mpirun.  For example:

           % /usr/local/bin/mpirun ...

       is equivalent to

           % mpirun --prefix /usr/local

   Exported Environment Variables
       All environment variables that are named in the form OMPI_* will
       automatically be exported to new processes on the local and remote
       nodes.  The -x option to mpirun can be used to export specific
       environment variables to the new processes.  While the syntax of the -x
       option allows the definition of new variables, note that the parser for
       this option is currently not very sophisticated - it does not even
       understand quoted values.  Users are advised to set variables in the
       environment and use -x to export them; not to define them.

   Setting MCA Parameters
       The -mca switch allows the passing of parameters to various MCA
       (Modular Component Architecture) modules.  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.).

       The -mca switch takes two arguments: <key> and <value>.  The <key>
       argument generally specifies which MCA module will receive the value.
       For example, the <key> "btl" is used to select which BTL to be used for
       transporting MPI messages.  The <value> argument is the value that is
       passed.  For example:

       mpirun -mca btl tcp,self -np 1 foo
           Tells Open MPI to use the "tcp" and "self" BTLs, and to run a
           single copy of "foo" an allocated node.

       mpirun -mca btl self -np 1 foo
           Tells Open MPI to use the "self" BTL, and to run a single copy of
           "foo" an allocated node.

       The -mca switch can be used multiple times to specify different <key>
       and/or <value> arguments.  If the same <key> is specified more than
       once, the <value>s are concatenated with a comma (",") separating them.

       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.  The form of
       the environment variables that Open MPI sets is:

             OMPI_MCA_<key>=<value>

       Thus, the -mca switch overrides any previously set environment
       variables.  The -mca settings similarly override MCA parameters set in
       the $OPAL_PREFIX/etc/openmpi-mca-params.conf or $HOME/.openmpi/mca-
       params.conf file.

       Unknown <key> arguments are still set as environment variable -- they
       are not checked (by mpirun) for correctness.  Illegal or incorrect
       <value> arguments may or may not be reported -- it depends on the
       specific MCA module.

       To find the available component types under the MCA architecture, or to
       find the available parameters for a specific component, use the
       ompi_info command.  See the ompi_info(1) man page for detailed
       information on the command.

EXAMPLES
       Be sure also to see the examples throughout the sections above.

       mpirun -np 4 -mca btl ib,tcp,self prog1
           Run 4 copies of prog1 using the "ib", "tcp", and "self" BTL's for
           the transport of MPI messages.

       mpirun -np 4 -mca btl tcp,sm,self
           --mca btl_tcp_if_include ce0 prog1
           Run 4 copies of prog1 using the "tcp", "sm" and "self" BTLs for the
           transport of MPI messages, with TCP using only the ce0 interface to
           communicate.  Note that other BTLs have similar if_include MCA
           parameters.

RETURN VALUE
       mpirun returns 0 if all ranks started by mpirun exit after calling
       MPI_FINALIZE.  A non-zero value is returned if an internal error
       occurred in mpirun, or one or more ranks exited before calling
       MPI_FINALIZE.  If an internal error occurred in mpirun, the
       corresponding error code is returned.  In the event that one or more
       ranks exit before calling MPI_FINALIZE, the return value of the rank of
       the process that mpirun first notices died before calling MPI_FINALIZE
       will be returned.  Note that, in general, this will be the first rank
       that died but is not guaranteed to be so.



1.4.1                            Jan 14, 2010                        MPIRUN(1)
