source: proiecte/hpl/openmpi_compiled/share/man/man1/orterun.1 @ 97

.\" Copyright (c) 2009      Cisco Systems, Inc.  All rights reserved.
.\" Copyright (c) 2008-2009 Sun Microsystems, Inc.  All rights reserved.
.\"
.\" Man page for ORTE's orterun command
.\" 
.\" .TH name     section center-footer   left-footer  center-header
.TH MPIRUN 1 "Dec 08, 2009" "1.4" "Open MPI"
.\" **************************
.\"    Name Section
.\" **************************
.SH NAME
.
orterun, mpirun, mpiexec \- Execute serial and parallel jobs in Open MPI.

.B Note:
\fImpirun\fP, \fImpiexec\fP, and \fIorterun\fP are all synonyms for each
other.  Using any of the names will produce the same behavior.
.
.\" **************************
.\"    Synopsis Section
.\" **************************
.SH SYNOPSIS
.
.PP
Single Process Multiple Data (SPMD) Model:

.B mpirun
[ options ] 
.B <program>
[ <args> ]
.P

Multiple Instruction Multiple Data (MIMD) Model:

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

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

    \fB%\fP /usr/local/bin/mpirun ...

is equivalent to

    \fB%\fP mpirun --prefix /usr/local

.
.\" **************************
.\"    Quick Summary Section
.\" **************************
.SH 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:

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

This will run X copies of \fI<program>\fR in your current run-time
environment (if running under a supported resource manager, Open MPI's
\fImpirun\fR will usually automatically use the corresponding resource manager
process starter, as opposed to, for example, \fIrsh\fR or \fIssh\fR,
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 Section
.\" **************************
.SH OPTIONS
.
.I 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.
.\"
.\" Start options listing
.\"    Indent 10 characters from start of first column to start of second column
.TP 10
.B <program>
The program executable. This is identified as the first non-recognized argument
to mpirun.
.
.
.TP
.B <args>
Pass these run-time arguments to every new process.  These must always
be the last arguments to \fImpirun\fP. If an app context file is used,
\fI<args>\fP will be ignored.
.
.
.TP
.B -h\fR,\fP --help
Display help for this command
.
.
.TP
.B -q\fR,\fP --quiet
Suppress informative messages from orterun during application execution.
.
.
.TP
.B -v\fR,\fP --verbose
Be verbose
.
.
.TP
.B -V\fR,\fP --version
Print version number.  If no other arguments are given, this will also
cause orterun to exit.
.
.
.
.
.P
To specify which hosts (nodes) of the cluster to run on:
.
.
.TP
.B -H\fR,\fP -host\fR,\fP --host \fR<host1,host2,...,hostN>\fP
List of hosts on which to invoke processes.
.
.
.TP
.B
-hostfile\fR,\fP --hostfile \fR<hostfile>\fP
Provide a hostfile to use. 
.\" JJH - Should have man page for how to format a hostfile properly.
.
.
.TP
.B -machinefile\fR,\fP --machinefile \fR<machinefile>\fP
Synonym for \fI-hostfile\fP.
.
.
.
.
.P
To specify the number of processes to launch:
.
.
.TP
.B -c\fR,\fP -n\fR,\fP --n\fR,\fP -np \fR<#>\fP
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. 
.
.
.TP
.B -npersocket\fR,\fP --npersocket <#persocket>
On each node, launch this many processes times the number of processor
sockets on the node.
The \fI-npersocket\fP option also turns on the \fI-bind-to-socket\fP option.
.
.
.TP
.B -npernode\fR,\fP --npernode <#pernode>
On each node, launch this many processes.
.
.
.TP
.B -pernode\fR,\fP --pernode
On each node, launch one process -- equivalent to \fI-npernode\fP 1.
.
.
.
.
.P
To map processes to nodes:
.
.
.TP
.B -loadbalance\fR,\fP --loadbalance
Uniform distribution of ranks across all nodes. See more detailed description below.
.
.TP
.B -nolocal\fR,\fP --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 \fB--host\fR or any other host-specifying mechanism.
.
.TP
.B -nooversubscribe\fR,\fP --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.
.
.TP
.B -bynode\fR,\fP --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.
.
.
.
.
.P
For process binding:
.
.TP
.B -bycore\fR,\fP --bycore
Associate processes with successive cores
if used with one of the \fI-bind-to-*\fP options.
.
.TP
.B -bysocket\fR,\fP --bysocket
Associate processes with successive processor sockets
if used with one of the \fI-bind-to-*\fP options.
.
.TP
.B -cpus-per-proc\fR,\fP --cpus-per-proc <#perproc>
Use the number of cores per process
if used with one of the \fI-bind-to-*\fP options.
.
.TP
.B -cpus-per-rank\fR,\fP --cpus-per-rank <#perrank>
Alias for \fI-cpus-per-proc\fP.
.
.TP
.B -bind-to-core\fR,\fP --bind-to-core
Bind processes to cores.
.
.TP
.B -bind-to-socket\fR,\fP --bind-to-socket
Bind processes to processor sockets.
.
.TP
.B -bind-to-none\fR,\fP --bind-to-none
Do not bind processes.  (Default.)
.
.TP
.B -report-bindings\fR,\fP --report-bindings
Report any bindings for launched processes.
.
.TP
.B -slot-list\fR,\fP --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.
.
.
.
.
.P
For rankfiles:
.
.
.TP
.B -rf\fR,\fP --rankfile <rankfile>
Provide a rankfile file.
.
.
.
.
.P
To manage standard I/O:
.
.
.TP
.B -output-filename\fR,\fP --output-filename \fR<filename>\fP
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.
.
.
.TP
.B -stdin\fR,\fP --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 \fInone\fP,
indicating that no ranks are to receive stdin.
.
.
.TP
.B -tag-output\fR,\fP --tag-output
Tag each line of output to stdout, stderr, and stddiag with \fB[jobid, rank]<stdxxx>\fP indicating the process jobid
and rank that generated the output, and the channel which generated it.
.
.
.TP
.B -timestamp-output\fR,\fP --timestamp-output
Timestamp each line of output to stdout, stderr, and stddiag.
.
.
.TP
.B -xml\fR,\fP --xml
Provide all output to stdout, stderr, and stddiag in an xml format.
.
.
.TP
.B -xterm\fR,\fP --xterm \fR<ranks>\fP
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.
.B 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.
.
.
.
.
.P
To manage files and runtime environment:
.
.
.TP
.B -path\fR,\fP --path \fR<path>\fP
<path> that will be used when attempting to locate the requested
executables.  This is used prior to using the local PATH setting.
.
.
.TP
.B --prefix \fR<dir>\fP
Prefix directory that will be used to set the \fIPATH\fR and
\fILD_LIBRARY_PATH\fR on the remote node before invoking Open MPI or
the target process.  See the "Remote Execution" section, below.
.
.
.TP
.B --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.
.
.
.TP
.B --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.
.
.
.TP
.B --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.
.
.
.TP
.B --tmpdir \fR<dir>\fP
Set the root for the session directory tree for mpirun only.
.
.
.TP
.B -wd \fR<dir>\fP
Synonym for \fI-wdir\fP.
.
.
.TP
.B -wdir \fR<dir>\fP
Change to the directory <dir> before the user's program executes.
See the "Current Working Directory" section for notes on relative paths.
.B Note:
If the \fI-wdir\fP option appears both on the command line and in an
application context, the context will take precedence over the command
line.
.
.
.TP
.B -x \fR<env>\fP
Export the specified environment variables to the remote nodes before
executing the program.  Only one environment variable can be specified
per \fI-x\fP option.  Existing environment variables can be specified
or new variable names specified with corresponding values.  For
example:
    \fB%\fP mpirun -x DISPLAY -x OFILE=/tmp/out ...

The parser for the \fI-x\fP option is not very sophisticated; it does
not even understand quoted values.  Users are advised to set variables
in the environment, and then use \fI-x\fP to export (not define) them.
.
.
.
.
.P
Setting MCA parameters:
.
.
.TP
.B -gmca\fR,\fP --gmca \fR<key> <value>\fP
Pass global MCA parameters that are applicable to all contexts. \fI<key>\fP is
the parameter name; \fI<value>\fP is the parameter value.
.
.
.TP
.B -mca\fR,\fP --mca <key> <value>
Send arguments to various MCA modules.  See the "MCA" section, below.
.
.
.
.
.P
For debugging:
.
.
.TP
.B -debug\fR,\fP --debug
Invoke the user-level debugger indicated by the \fIorte_base_user_debugger\fP
MCA parameter.
.
.
.TP
.B -debugger\fR,\fP --debugger
Sequence of debuggers to search for when \fI--debug\fP is used (i.e.
a synonym for \fIorte_base_user_debugger\fP MCA parameter).
.
.
.TP
.B -tv\fR,\fP --tv
Launch processes under the TotalView debugger.
Deprecated backwards compatibility flag. Synonym for \fI--debug\fP.
.
.
.
.
.P
There are also other options:
.
.
.TP
.B -aborted\fR,\fP --aborted \fR<#>\fP
Set the maximum number of aborted processes to display.
.
.
.TP
.B --app \fR<appfile>\fP
Provide an appfile, ignoring all other command line options.
.
.
.TP
.B -cf\fR,\fP --cartofile \fR<cartofile>\fP
Provide a cartography file.
.
.
.TP
.B --hetero
Indicates that multiple app_contexts are being provided that are a mix of 32/64-bit binaries.
.
.
.TP
.B -leave-session-attached\fR,\fP --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.
.
.
.TP
.B -ompi-server\fR,\fP --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.
.
.
.TP
.B -wait-for-server\fR,\fP --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 \fImpirun\fP 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.
.
.
.TP
.B -server-wait-time\fR,\fP --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.
.
.
.
.
.P
The following options are useful for developers; they are not generally
useful to most ORTE and/or MPI users:
.
.TP
.B -d\fR,\fP --debug-devel
Enable debugging of the OmpiRTE (the run-time layer in Open MPI).
This is not generally useful for most users.
.
.
.TP
.B --debug-daemons
Enable debugging of any OmpiRTE daemons used by this application.
.
.
.TP
.B --debug-daemons-file
Enable debugging of any OmpiRTE daemons used by this application, storing
output in files.
.
.
.TP
.B -launch-agent\fR,\fP --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
\fRorted -mca odls_base_verbose 5\fR allows the developer to ask the orted for debugging output
without clutter from mpirun itself.
.
.
.TP
.B --noprefix
Disable the automatic --prefix behavior
.
.
.P
There may be other options listed with \fImpirun --help\fP.
.
.
.\" **************************
.\"    Description Section
.\" **************************
.SH DESCRIPTION
.
One invocation of \fImpirun\fP starts an MPI application running under Open
MPI. If the application is single process multiple data (SPMD), the application
can be specified on the \fImpirun\fP 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.
.PP
An application context describes the MIMD program set including all arguments
in a separate file.
.\"See appcontext(5) for a description of the application context syntax.
This file essentially contains multiple \fImpirun\fP 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.
.PP
Extended command line arguments allow for the description of the application
layout on the command line using colons (\fI:\fP) 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).
.
.
.
.SS Specifying Host Nodes
.
Host nodes can be identified on the \fImpirun\fP command line with the \fI-host\fP
option or in a hostfile.
.
.PP
For example,
.
.TP 4
mpirun -H aa,aa,bb ./a.out
launches two processes on node aa and one on bb.
.
.PP
Or, consider the hostfile
.

   \fB%\fP cat myhostfile
   aa slots=2
   bb slots=2
   cc slots=2

.
.PP
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.
.
.PP
.
.TP 4
mpirun -hostfile myhostfile ./a.out
will launch two processes on each of the three nodes.
.
.TP 4
mpirun -hostfile myhostfile -host aa ./a.out
will launch two processes, both on node aa.
.
.TP 4
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.
.
.SS Specifying Number of Processes
.
As we have just seen, the number of processes to run can be set using the
hostfile.  Other mechanisms exist.
.
.PP
The number of processes launched can be specified as a multiple of the
number of nodes or processor sockets available.  For example,
.
.TP 4
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 \fI-npersocket\fP option also turns on the \fI-bind-to-socket\fP option,
which is discussed in a later section.
.
.TP 4
mpirun -H aa,bb -npernode 2 ./a.out
launches processes 0-1 on node aa and processes 2-3 on node bb.
.
.TP 4
mpirun -H aa,bb -npernode 1 ./a.out
launches one process per host node.
.
.TP 4
mpirun -H aa,bb -pernode ./a.out
is the same as \fI-npernode\fP 1.
.
.
.PP
Another alternative is to specify the number of processes with the
\fI-np\fP option.  Consider now the hostfile
.

   \fB%\fP cat myhostfile
   aa slots=4
   bb slots=4
   cc slots=4

.
.PP
Now,
.
.TP 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 \fI-np\fP option indicated
that only 6 processes should be launched.
.
.SS Mapping Processes to Nodes
.
The examples above illustrate the default mapping of process ranks
to nodes.  This mapping can also be controlled with various
\fImpirun\fP options.  Here, we consider the same hostfile as
above with \fI-np\fP 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
.
.PP
The \fI-loadbalance\fP option tries to spread processes out fairly among the
nodes.
.
.PP
The \fI-bynode\fP option does likewise but numbers the processes in "by node"
in a round-robin fashion.
.
.PP
The \fI-nolocal\fP option prevents any processes from being mapped onto the
local host (in this case node aa).  While \fImpirun\fP typically consumes
few system resources, \fI-nolocal\fP can be helpful for launching very
large jobs where \fImpirun\fP may actually need to use noticable amounts
of memory and/or processing time.
.
.PP
Just as \fI-np\fP can specify fewer processes than there are slots, it can
also oversubscribe the slots.  For example, with the same hostfile:
.
.TP 4
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.
.
.PP
One can also specify limits to oversubscription.  For example, with the same
hostfile:
.
.TP 4
mpirun -hostfile myhostfile -np 14 -nooversubscribe ./a.out
will produce an error since \fI-nooversubscribe\fP prevents oversubscription.
.
.PP
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
.
.PP
The \fImax_slots\fP field specifies such a limit.  When it does, the
\fIslots\fP value defaults to the limit.  Now:
.
.TP 4
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.
.
.PP
Using the \fI--nooversubscribe\fR option can be helpful since Open MPI
currently does not get "max_slots" values from the resource manager.
.
.PP
Of course, \fI-np\fP can also be used with the \fI-H\fP or \fI-host\fP
option.  For example,
.
.TP 4
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.
.
.PP
And here is a MIMD example:
.
.TP 4
mpirun -H aa -np 1 hostname : -H bb,cc -np 2 uptime
will launch process 0 running \fIhostname\fP on node aa and processes 1 and 2
each running \fIuptime\fP on nodes bb and cc, respectively.
.
.SS 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.
.
.PP
To bind processes, one must first associate them with the resources
on which they should run.  For example, the \fI-bycore\fP option
associates the processes on a node with successive cores.  Or,
\fI-bysocket\fP associates the processes with successive processor sockets,
cycling through the sockets in a round-robin fashion if necessary.
And \fI-cpus-per-proc\fP indicates how many cores to bind per process.
.
.PP
But, such association is meaningless unless the processes are actually
bound to those resources.  The binding option specifies the granularity
of binding -- say, with \fI-bind-to-core\fP or \fI-bind-to-socket\fP.
One can also turn binding off with \fI-bind-to-none\fP, which is
typically the default.
.
.PP
Finally, \fI-report-bindings\fP can be used to report bindings.
.
.PP
As an example, consider a node with two processor sockets, each comprising
four cores.  We run \fImpirun\fP with \fI-np 4 -report-bindings\fP 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
.
.PP
Here, \fI-report-bindings\fP 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.
.
.PP
Open MPI's support for process binding depends on the underlying
operating system.  Therefore, processing binding may not be available
on every system.
.
.PP
Process binding can also be set with MCA parameters.
Their usage is less convenient than that of \fImpirun\fP options.
On the other hand, MCA parameters can be set not only on the \fImpirun\fP
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
.
.PP
The \fIorte_process_binding\fP value can also take on the
\fI:if-avail\fP 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
.
.
.SS 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.
. 
.
.SS Application Context or Executable Program?
.
To distinguish the two different forms, \fImpirun\fP
looks on the command line for \fI--app\fP 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.
.
.
.
.SS 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 \fI--path\fP option.  If there is no \fI--path\fP option set or
if the file is not found at the \fI--path\fP location, then Open MPI
will search the user's PATH environment variable as defined on the
source node(s).
.PP
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 \fImpirun\fP. 
.
.
.
.SS Current Working Directory
.
The \fI\-wdir\fP mpirun option (and its synonym, \fI\-wd\fP) 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.
.PP
If the \fI\-wdir\fP option appears both in a context file and on the
command line, the context file directory will override the command
line value.
.PP
If the \fI-wdir\fP option is specified, Open MPI will attempt to
change to the specified directory on all of the remote nodes. If this
fails, \fImpirun\fP will abort.
.PP
If the \fI-wdir\fP option is \fBnot\fP specified, Open MPI will send
the directory name where \fImpirun\fP 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 exit on
that node), then Open MPI will use the default directory determined by
the starter.
.PP
All directory changing occurs before the user's program is invoked; it
does not wait until \fIMPI_INIT\fP is called.  
.
.
.
.SS 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 \fImpirun\fP.
.B Note:
The node that invoked \fImpirun\fP need not be the same as the node where the
MPI_COMM_WORLD rank 0 process resides. Open MPI handles the redirection of
\fImpirun\fP's standard input to the rank 0 process.
.PP
Open MPI directs UNIX standard output and error from remote nodes to the node
that invoked \fImpirun\fP and prints it on the standard output/error of
\fImpirun\fP.
Local processes inherit the standard output/error of \fImpirun\fP and transfer
to it directly.
.PP
Thus it is possible to redirect standard I/O for Open MPI applications by
using the typical shell redirection procedure on \fImpirun\fP.

      \fB%\fP mpirun -np 2 my_app < my_input > my_output

Note that in this example \fIonly\fP the MPI_COMM_WORLD rank 0 process will
receive the stream from \fImy_input\fP 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 \fImy_output\fP file. 
.
.
.
.SS 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.
.
.PP
SIGUSR1 and SIGUSR2 signals received by orterun are propagated to
all processes in the job.
.
.PP
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.
.
.PP
Other signals are not currently propagated
by orterun.
.
.
.SS Process Termination / Signal Handling
.
During the run of an MPI application, if any rank dies abnormally
(either exiting before invoking \fIMPI_FINALIZE\fP, or dying as the result of a
signal), \fImpirun\fP will print out an error message and kill the rest of the
MPI application.
.PP
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 \fIMPI_SEND\fP (perhaps because
a bad buffer was passed in) and a user signal handler is invoked, if this user
handler attempts to invoke \fIMPI_FINALIZE\fP, Bad Things could happen since
Open MPI was already "in" MPI when the error occurred.  Since \fImpirun\fP
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.
.
.
.
.SS 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 \fIrsh\fR launch module, for example, uses either
\fIrsh\fR/\fIssh\fR 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 \fILD_LIBRARY_PATH\fR environment
variable to be set, care must be taken to ensure that it is correctly
set when booting Open MPI.
.PP
See the "Remote Execution" section for more details.
.
.
.SS Remote Execution
.
Open MPI requires that the \fIPATH\fR environment variable be set to
find executables on remote nodes (this is typically only necessary in
\fIrsh\fR- or \fIssh\fR-based environments -- batch/scheduled
environments typically copy the current environment to the execution
of remote jobs, so if the current environment has \fIPATH\fR and/or
\fILD_LIBRARY_PATH\fR 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 \fILD_LIBRARY_PATH\fR environment
variable set on remote nodes as well (especially to find the shared
libraries required to run user MPI applications).
.PP
However, it is not always desirable or possible to edit shell
startup files to set \fIPATH\fR and/or \fILD_LIBRARY_PATH\fR.  The
\fI--prefix\fR option is provided for some simple configurations where
this is not possible.
.PP
The \fI--prefix\fR 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 \fIPATH\fR and \fILD_LIBRARY_PATH\fR
before executing any Open MPI or user applications.  This allows
running Open MPI jobs without having pre-configured the \fIPATH\fR and
\fILD_LIBRARY_PATH\fR on the remote nodes.
.PP
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 \fIPATH\fR 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
\fILD_LIBRARY_PATH\fR on the remote node.  For example:
.TP 15
Local bindir:
/local/node/directory/bin
.TP
Local libdir:
/local/node/directory/lib64
.PP
If the following command line is used:

    \fB%\fP mpirun --prefix /remote/node/directory

Open MPI will add "/remote/node/directory/bin" to the \fIPATH\fR
and "/remote/node/directory/lib64" to the \fLD_LIBRARY_PATH\fR on the
remote node before attempting to execute anything.
.PP
Note that \fI--prefix\fR can be set on a per-context basis, allowing
for different values for different nodes.
.PP
The \fI--prefix\fR 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.  
.PP
Note that executing \fImpirun\fR via an absolute pathname is
equivalent to specifying \fI--prefix\fR without the last subdirectory
in the absolute pathname to \fImpirun\fR.  For example:

    \fB%\fP /usr/local/bin/mpirun ...

is equivalent to

    \fB%\fP mpirun --prefix /usr/local
.
.
.
.SS 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 \fI\-x\fP option to \fImpirun\fP can be used to export specific environment
variables to the new processes.  While the syntax of the \fI\-x\fP
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 \fI\-x\fP to export them; not to define them.
.
.
.
.SS Setting MCA Parameters
.
The \fI-mca\fP switch allows the passing of parameters to various MCA
(Modular Component Architecture) modules.
.\" Open MPI's MCA modules are described in detail in ompimca(7).
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.).
.PP
The \fI-mca\fP switch takes two arguments: \fI<key>\fP and \fI<value>\fP.
The \fI<key>\fP argument generally specifies which MCA module will receive the value.
For example, the \fI<key>\fP "btl" is used to select which BTL to be used for
transporting MPI messages.  The \fI<value>\fP argument is the value that is
passed.
For example: 
.
.TP 4
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.
.
.TP
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.
.\" And so on.  Open MPI's BTL MCA modules are described in ompimca_btl(7).
.PP
The \fI-mca\fP switch can be used multiple times to specify different
\fI<key>\fP and/or \fI<value>\fP arguments.  If the same \fI<key>\fP is
specified more than once, the \fI<value>\fPs are concatenated with a comma
(",") separating them.
.PP
Note that the \fI-mca\fP switch is simply a shortcut for setting environment variables.
The same effect may be accomplished by setting corresponding environment
variables before running \fImpirun\fP.
The form of the environment variables that Open MPI sets is:

      OMPI_MCA_<key>=<value>
.PP
Thus, the \fI-mca\fP switch overrides any previously set environment
variables.  The \fI-mca\fP settings similarly override MCA parameters set
in the
$OPAL_PREFIX/etc/openmpi-mca-params.conf or $HOME/.openmpi/mca-params.conf
file.
.
.PP
Unknown \fI<key>\fP arguments are still set as
environment variable -- they are not checked (by \fImpirun\fP) for correctness.
Illegal or incorrect \fI<value>\fP arguments may or may not be reported -- it
depends on the specific MCA module.
.PP
To find the available component types under the MCA architecture, or to find the
available parameters for a specific component, use the \fIompi_info\fP command.
See the \fIompi_info(1)\fP man page for detailed information on the command.
.
.\" **************************
.\"    Examples Section
.\" **************************
.SH EXAMPLES
Be sure also to see the examples throughout the sections above.
.
.TP 4
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.
.
.
.TP 4
mpirun -np 4 -mca btl tcp,sm,self 
.br
--mca btl_tcp_if_include ce0 prog1
.br
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.
.
.\" **************************
.\"    Diagnostics Section
.\" **************************
.
.\" .SH DIAGNOSTICS
.\".TP 4
.\"Error Msg:
.\"Description
.
.\" **************************
.\"    Return Value Section
.\" **************************
.
.SH RETURN VALUE
.
\fImpirun\fP returns 0 if all ranks started by \fImpirun\fP 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 \fImpirun\fP 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.
.
.\" **************************
.\"    See Also Section
.\" **************************
.
.\" .SH SEE ALSO
.\" orted(1), ompi-server(1)