add intel

Currently the command 'add intel' will set up the environment for version 8.1 of the Intel compiler. To use the earlier 7.1 version of the Intel compilers use the command 'add intel-71'.

Once one of these files have been executed, the Intel compilers may be invoked with the icc, icpc, and ifort commands for the C, C++, and Fortran77/90 compilers respectively.

Intel 7.1 compilers were invoked with icc for the C/C++ compiler and ifc for the Fortran compiler.

Compiling a Serial Program
The following command would generate an executable named 'exec' from the Fortran source code file named 'code.f' with a moderately high level of optimization.

ifort -O3 -axW -o exec code.f

Compiling a Parallel Program
Intel compilers can generate shared memory parallel executables. However, the cluster nodes have only two processors, so shared memory parallelization is unlikely to provide benefit on the henry2 Linux cluster.

Distributed memory parallel programs written with MPI function calls are currently the most appropriate programming model to achieve good performance from commodity clusters such as henry2.

MPI parallel programs compiled with the Intel compilers should use the mpif77, mpif90, mpicc, or mpiCC commands to link with the MPICH libraries.

The following command line would compile an MPI code with a high level of optimization:

mpif90 -o exec -O3 -axW code.f

The MPICH MPI library is used when the mpi* commands are invoked with the Intel compiler environments.

When C and Fortran object files are linked together, the -static-libcxa flag avoids a run-time error. For example, the executable pring produced by

ifort -c ring.f
icc -c host.c 
mpif90 -o pring host.o ring.o -static-libcxa 

Any of these compilers (and in particular the mpiCC) compiler are prone to run-time errors when shared libraries are used. Using a -static flag is therefore recommended. For example,

mpiCC greetings2.c -o greetings2 -static