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Intel Compilers
The native, and recommended, compilers on GALILEO100 are the Intel ones, since the architecture is based on Intel processors and therefore using the Intel compilers may result in a significant improvement in performance and stability of your code. On the cluster is installed the new suite Intel OneAPI. Initialize the environment with the module command:
> module load intel/oneapi-2021--binary
> module list
Currently Loaded Modulefiles:
intel/oneapi-2021--binary
The suite contains the new Intel oneAPI nextgen compilers (icx, icpx, ifx) and the classic compilers (icc, icpc, ifort):
| Classic | oneAPI | Notes | |
|---|---|---|---|
| C/C++ compilers | icc/icpc | icx/icpx |
|
| Fortran compilers | ifort | ifx |
|
NOTE:
- ICX is a new compiler. It has functional and behavioral differences compared to ICC. You can expect some porting will be needed for existing applications using ICC. According to Intel, the transition from ICC Classic to ICX is smooth and effortless. However, you must port and tune any existing applications from ICC Classic to ICX. Please refer to the official Intel Porting Guide for ICC Users to DPCPP or ICX
- IFORT is a completely new compiler. According to Intel, although considerable effort is being made to make the transition from ifort to ifx as smooth and as effortless as possible, customers can expect that some effort may be required to tune their application. IFORT will remain Intel’s recommended production compiler until ifx has performance and features superior to ifort. Please refer to the official Intel Porting Guide for ifort Users to ifx
- Please refer to the official Intel C++ Developer Guide and Reference and Fortran Developer Guide and Reference for an exhaustive list of compiler options
The documentation can be obtained with the man command after loading the relevant module:
> man ifort > man icc
Some miscellaneous flags are described in the following:
-extend_source Extend over the 77 column F77's limit -free / -fixed Free/Fixed form for Fortran -ip Enables additional interprocedural optimization for single-file compilation -ipo Enables interprocedural optimization between files - whole program optimisation
-qopenmp enables the parallelizer to generate multi-threaded code based on OpenMP directives
NOTE for the migration from Galileo to Galileo100: In principle, binaries generated on Galileo should work, but we strongly recommend you to reinstall all your software applications since on Galileo100 there is a different Operating System (Centos 8.3).
GNU compilers
The gnu compilers are always available but they are not the best optimizing compilers, especially for an IntelOneAPIIntel OneAPI-based cluster like GALILEO100.
For a more recent version of the compiler, initialize the environment with the module command:
> module load gnu
The name of the GNU compilers are:
- g77: Fortran77 compiler
- gfortran: Fortran compiler with "gnu" standard
- gcc: C compiler
- g++: C++ compiler
The "gnu" standard is the default value for the -std option. It specifies a superset of the latest Fortran standard that includes all of the extensions supported by GNU Fortran, although warnings will be given for obsolete extensions not recommended for use in new code. To change the standard to which the program is expected to conform, set the -std option to one of the possible values (f95, f2003, f2008, f2018, gnu, or legacy).
The documentation can be obtained with the man command:
> man gfortan > man gcc
Some miscellaneous flags are described in the following:
-ffixed-line-length-132 To extend over the 77 column F77's limit -ffree-form / -ffixed-form Free/Fixed form for Fortran
-fopenmp Enable handling of OpenMP directives "#pragma omp" in C/C++ and "!$omp" in Fortran.
When -fopenmp is specified, the compiler generates parallel code according to the
OpenMP Application Program Interface v4.5. This option implies -pthread and -fopenmp-simd
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