The MPI package provides variables and a command that may be needed for some scripts in mpiSpecTcl. If you are using the 7.0 skeleton, it's SpecTclInit.tcl automatically loads the package. On the other hand, if you are porting from an earlier version of SpecTcl and have customizd SpecTclInit.tcl; add the following lines to your SpecTclInit.tcl file:
Example C-1. Loading the mpi Tcl package
load [file join $SpecTclHome lib/libMPITclPackage.so]
package require mpi
Note that we add these lines to SpecTclinit.tcl as it is run in all processes while SpecTclRC.tcl is only run in the root process.
The mpi Tcl package addressses the following concerns:
Allowing scripts to know if they are running in parallel or serial SpecTcl.
Allowing scripts to determine which mpi rank they are running in.
Allowing scripts to determine under which role they are running.
Allowing scripts run in the root process to run in other processes of the job.
The mpi Tcl package creates the ::mpi:: namespace and defines the following variables:
mpi::environmentProvides the environment under which the application is running. This is mpi if running parallel and serial if not.
mpi::rank
Provides the numeric rank of the process. If
mpi::environment is
serial, this will be 0
mpi::role
Provides the textual process role. This can be one of
root, event-sink or
worker. If mpi::environment
is serial This will be root
The mpi package also provides the mpi::send which submits a script to be executed in specified ranks/roles. Note that the script is broadcast to all ranks via the Tcl command pump and the receiver determines if it should be run. This implies that mpi::send should only be used in the root rank.
Complete documentation of the mpi::send