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GNU/Linux |
RedHat 6.2(Zoot) |
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lamexec(1) |
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lamexec − Run non-MPI programs on LAM nodes.
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lamexec [-fhvD] [-c <#> | -np <#>] [-nw | -w] [-pty] [-s <node>] [-x VAR1[=VALUE1][,VAR2[=VALUE2],...]] [<nodes>] <program> [-- <args>] |
lamexec is essentially a clone of the mpirun(1), but is intended for non-MPI programs.
One invocation of lamexec starts a non-MPI application running under LAM. To start the same program on all LAM nodes, the application can be specified on the lamexec command line. To start multiple applications on the LAM nodes, an application schema is required in a separate file. See appschema(5) for a description of the application schema syntax, but it essentially contains multiple lamexec 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 schema.
Application
Schema or Executable Program?
To distinguish the two different forms, lamexec looks
on the command line for <nodes> or the -c
option. If neither is specified, then the file named on the
command line is assumed to be an application schema. If
either one or both are specified, then the file is assumed
to be an executable program. If <nodes> and -c
both are specified, then copies of the program are started
on the specified nodes according to an internal LAM
scheduling policy. Specifying just one node effectively
forces LAM to run all copies of the program in one place. If
-c is given, but not <nodes>, then all LAM
nodes are used. If <nodes> is given, but not
-c, then one copy of the program is run on each
node.
Program
Transfer
By default, LAM searches for executable programs on the
target node where a particular instantiation will run. If
the file system is not shared, the target nodes are
homogeneous, and the program is frequently recompiled, it
can be convenient to have LAM transfer the program from a
source node (usually the local node) to each target node.
The -s option specifies this behavior and identifies
the single source node.
Locating
Files
LAM looks for an executable program by searching the
directories in the user’s PATH environment variable as
defined on the source node(s). This behavior is consistent
with logging into the source node and executing the program
from the shell. On remote nodes, the "." path is
the home directory.
LAM looks for an application schema in three directories: the local directory, the value of the LAMAPPLDIR environment variable, and LAMHOME/boot, where LAMHOME is the LAM installation directory.
Standard
I/O
LAM directs UNIX standard input to /dev/null on all remote
nodes. On the local node that invoked lamexec,
standard input is inherited from lamexec. The default
is what used to be the -w option to prevent conflicting
access to the terminal.
LAM directs UNIX standard output and error to the LAM daemon on all remote nodes. LAM ships all captured output/error to the node that invoked lamexec and prints it on the standard output/error of lamexec. Local processes inherit the standard output/error of lamexec and transfer to it directly.
Thus it is possible to redirect standard I/O for LAM applications by using the typical shell redirection procedure on lamexec.
% lamexec N my_app < my_input > my_output
The −f option avoids all the setup required to support standard I/O described above. Remote processes are completely directed to /dev/null and local processes inherit file descriptors from lamboot(1).
Pseudo-tty
support
The −pty option enabled pseudo-tty support for
process output. This allows, among other things, for line
buffered output from remote nodes (which is probably what
you want).
This option is not currently the default for lamexec because it has not been thoroughly tested on a variety of different Unixes. Users are encouraged to use −pty and report any problems back to the LAM Team.
Current
Working Directory
The current working directory for new processes created on
the local node is inherited from lamexec. The current
working directory for new processes created on remote nodes
is the remote user’s home directory. This default
behavior is overridden by the −D option.
The −D option will change the current working directory of new processes to the directory where the executable resides before the new user’s program is invoked.
An alternative to the −D option is the −wd option. −wd allows the user to specify an arbitrary current working directory (vs. the location of the executable). Note that the −wd option can be used in application schema files (see appschema(5)) as well.
Process
Environment
Processes in the application inherit their environment from
the LAM daemon upon the node on which they are running. The
environment of a LAM daemon is fixed upon booting of the LAM
with lamboot(1) and is inherited from the user’s
shell. On the origin node this will be the shell from which
lamboot(1) was invoked and on remote nodes this will be the
shell started by rsh(1). 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 the LAM.
Exported
Environment Variables
All environment variables that are named in the form
LAM_MPI_* will automatically be exported to new processes on
the local and remote nodes. This exporting may be inhibited
with the −nx option.
Additionally, the −x option to lamexec 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.
lamexec N prog1
Load and execute prog1 on all nodes. Search for the executable file on each node.
lamexec -c 8 prog1
Run 8 copies of prog1 wherever LAM wants to run them.
lamexec n8-10 -v -nw -s n3 prog1 -- -q
Load and execute prog1 on nodes 8, 9, and 10. Search for prog1 on node 3 and transfer it to the three target nodes. Report as each process is created. Give "-q" as a command line to each new process. Do not wait for the processes to complete before exiting lamexec.
lamexec -v myapp
Parse the application schema, myapp, and start all processes specified in it. Report as each process is created.
lamexec N N -pty -wd /workstuff/output -x DISPLAY run_app.csh
Run the application "run_app.csh" (assumedly a C shell script) twice on each node in the system (ideal for 2-way SMPs). Also enable pseudo-tty support, change directory to /workstuff/output, and export the DISPLAY variable to the new processes (perhaps the shell script will invoke an X application such as xv to display output).
lamexec -np 5 -D ’pwd’/my_application
A common usage of lamexec in environments where a filesystem is shared between all nodes in the multicomputer, using the shell-escaped "pwd" command specifies the full name of the executable to run. This prevents the need for putting the directory in the path; the remote notes will have an absolute filename to execute (and change directory to it upon invocation).
lamexec: Exec format error
A non-ASCII character was detected in the application schema. This is usually a command line usage error where lamexec is expecting an application schema and an executable file was given.
lamexec: syntax error in application schema, line XXX
The application schema cannot be parsed because of a usage or syntax error on the given line in the file.
<filename>: No such file or directory
This error can occur in two cases. Either the named file cannot be located or it has been found but the user does not have sufficient permissions to execute the program or read the application schema.
mpimsg(1), mpirun(1), mpitask(1), loadgo(1)
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lamexec(1) | |