Methods of Specifying MP Prism Options

The major differences between starting Prism to work on a serial program and starting MP Prism are:

1. You must specify a number of processes to run, even when the message-passing program runs on a single process. Use the -n option to specify the number of processes.

2. You are actually starting multiple Prism processes, in a client/server model:

• There is one client MP Prism process for each process in the message-passing program. The MP Prism process attaches itself to the message-passing process to collect information about it.

• There is a single server Prism process that communicates with the MP Prism processes and provides the interface to the user. This process is referred to as Host Prism.

• The multiple MP Prism processes run on the nodes on which the message-passing processes are running.

You can specify where you want both Host Prism and the message-passing processes (along with their associated MP Prism processes) to run. You can do this either explicitly or by using defaults.

Specifying Where Host Prism Is to Run

If you simply issue the prism command with the -n argument and an integer value, MP Prism starts Host Prism on the node to which you are logged in. For example:

% prism -n 4

See "Entering Prism" for more information on starting Prism, and see the Sun MPI 4.0 Programming and Reference Guide for more information on starting Sun HPC programs in general.

Specifying MP Prism Command-line Options

If you are in MP Prism, you can also use the Prism options listed below to specify where you want the message-passing processes and their associated MP Prism processes to run.

• Use the -W argument to instruct Prism to start the specified number of processes, even when that number exceeds the number of processors. By default, Prism launches one process per processor. For example:

% prism -n 4 -W a.x

starts four processes, regardless of the number of processors.

• Use the Prism command-line arguments that support environment-specific options. For example:

  • Use the -bsubargs argument to provide Prism (when using the LSF environment) with bsub arguments. For example, using the C shell (csh), you can specify a preferred host by name.

% prism -n 4 -W -bsubargs '-m argos' a.x

Here, you requested four processes to be launched on host argos, wrapping if necessary.

• Use the -mprunargs argument to provide Prism (when using the CRE environment) with mprun arguments. For example, using the C shell (csh), you can specify a preferred host by name.

% prism -n 4 -W -mprunargs '-p delos' a.x

Here, you requested four processes to be launched on partition delos, wrapping if necessary.

If the bsub option itself uses quotation marks, refer to the documentation for your shell program for the syntax for handling quotes.

Specifying Environment-Specific Options After Launching Prism

Sun HPC ClusterTools 3.0 supports two run-time environments, Platform Computing's Load Sharing Facility (LSF), and the Cluster Runtime Environment (CRE). Prism runs on both environments. If you want to determine which environment is in effect, execute the script /opt/SUNWhpc/etc/hpc_rte from a shell prompt. For example:

% hpc_rte
lsf

Once you have entered Prism, you can issue environment-specific commands to specify any bsub (when using the LSF environment) or mprun (when using the CRE environment) options that you want to apply to your message-passing program.

Prism stores these options, then applies them when you start up a multiprocess program. Specifying the setting of a bsub option via the bsubargs command, or an mprun option via the mprunargs command, overrides the setting of the same option you have established via the prism command line. If it is an option that has otherwise not been specified, it is added to the existing settings.

The strings given to bsubargs or mprunargs should not contain the -I, -Ip, or -n flags, because Prism internally generates values for them, and the results will be undefined.

Using bsubargs

To specify a preferred host by name after you have entered Prism in the LSF environment, use the bsubargs command. For example:

(prism all) bsubargs -m argos

To remove any existing bsub options you have specified, issue the command

(prism all) bsubargs off

Within Prism, this removes options you have set via the command line.

Issuing the bsubargs command with no options shows the current bsub options.

The bsubargs command accepts a single string argument. Since this argument is issued within Prism, using the shell-specific syntax appropriate for the -bsubargs option causes errors. Also, each time that you issue the bsubargs command, the previously specified bsub options are replaced. To keep a list of options in effect, you must specify the entire list whenever you change any item in that list.

Using mprunargs

To specify a preferred partition by name after you have entered Prism in the CRE environment, use the mprunargs command. For example:

(prism all) bsubargs -p delos

To remove any existing mprun options you have specified, issue the command

(prism all) mprunargs off

Within Prism, this removes options you have set via the command line.

Issuing the mprunargs command with no options shows the current mprun options.

The mprunargs command accepts a single string argument. Since this argument is issued within Prism, using the shell-specific syntax appropriate for the -mprunargs option causes errors.