Provided by: openmpi-bin_1.4.3-2.1ubuntu3_i386 bug


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

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


       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


       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.


       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

       -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)

       -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

       -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

       -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

       --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.

              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,

       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.

              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

       -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.

              Enable   debugging   of   any   OmpiRTE  daemons  used  by  this

              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.

              Disable the automatic --prefix behavior

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


       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

       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


       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: Using Policies
       The  examples  above illustrate the default mapping of process ranks to
       nodes.  This mapping can also be controlled with various mpirun options
       that describe mapping policies.

       Consider the same hostfile as above, again with -np 6:

                                 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

       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  noticeable  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

       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

       Limits to oversubscription  can  also  be  specified  in  the  hostfile
        % 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

       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.

   Mapping Processes to Nodes: Using Arbitrary Mappings
       The mapping of process ranks to nodes can be prescribed not  just  with
       general  policies but also, if necessary, using arbitrary mappings that
       cannot be described by a simple policy.  One can  use  the  "sequential
       mapper,"  which reads the hostfile line by line, assigning processes to
       nodes in whatever order the hostfile specifies.  Use the -mca rmaps seq
       option.  For example, using the same hostfile as before

       mpirun -hostfile myhostfile ./a.out
           will launch three processes, on ranks aa, bb, and cc, respectively.
           The slot counts don't matter;  one process is launched per line  on
           whatever node is listed on the line.

       Another  way  to  specify arbitrary mappings is with a rank file, which
       gives you detailed control over process binding as  well.   Rank  files
       are discussed below.

   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 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

       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

       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 not async-signal-safe; see MPI_Init_thread(3)
       for details about MPI_THREAD_MULTIPLE and thread safety).  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

       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:


       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.


       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 eth0 prog1
           Run 4 copies of prog1 using the "tcp", "sm" and "self" BTLs for the
           transport  of  MPI messages, with TCP using only the eth0 interface
           to communicate.  Note that other BTLs have similar  if_include  MCA


       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.