
16 Cray T3E User’s Guide
2.3 Editing files
You can use the Emacs or vi editors on the T3E. To start Emacs, give the
command
emacs [options][filename]...
Here is an example:
emacs -nw main.f90
However, because your home directory is shared with other computers
at CSC, you can do your editing on some other system. We recommend
this approach, because it minimizes the interactive load on the T3E.
You get a short introduction to Emacs in Finnish by giving the command
help emacs
2.4 Compiling and running applications
Parallel programs on the Cray T3E can be either malleable or non-malleab-
le. Malleable executables can be run on any number of processing ele-
ments using the mpprun command. Non-malleable executables are fixed
at compile time to run on a specific number of processors.
If a program is to be non-malleable, it has to be compiled and linked
with the option -Xn (or -X n) indicating the number n of PEs. A program
with a fixed number of PEs can be started directly. For example, in the
following we use ten processors:
t3e% f90 -X 10 -o prog.x prog.f90
t3e% ./prog.x
To produce a malleable program, the source code can be compiled and
linked with the option -Xm, but since this is the default, you can usually
omit the flag. To choose the number of processors, the executable has
to be run using the mpprun command.
The following example compiles, links and executes twice a program
called prog.x. The first invocation uses five (5) processors and the
second twelve (12) processors:
t3e% f90 -o prog.x prog.f90
t3e% mpprun -n 5 ./prog.x
t3e% mpprun -n 12 ./prog.x
Note: if the program is executed only on one processor, it will not be
run on the application nodes, and thus it might be interrupted by other
activities.
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