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Controlling the Programming Environment on Commodity Clusters

See this article in context within the following user guides: Rhea

Upon login, default versions of the Intel compiler and OpenMPI (Message Passing Interface) libraries are added to each user’s environment through a programming environment (PE) module. Users do not need to make any environment changes to use the default version of Intel and OpenMPI.

Changing Compilers

If a different compiler is required, it is important to use the correct environment for each compiler. To aid users in pairing the correct compiler and environment, programming environment modules are provided. The programming environment modules will load the correct pairing of compiler version, message passing libraries, and other items required to build and run code. We highly recommend that the programming environment modules be used when changing compiler vendors.

The following programming environment modules are available on OLCF commodity clusters:

  • PE-intel
  • PE-pgi
  • PE-gnu

To change the default loaded Intel environment to the GCC environment use:

$ module unload PE-intel 
$ module load PE-gnu

Or alternatively:

$ module swap PE-intel PE-gnu
Changing Versions of the Same Compiler

To use a specific compiler version, you must first ensure the compiler’s PE module is loaded, and then swap to the correct compiler version. For example, the following will configure the environment to use the GCC compilers, then load a non-default GCC compiler version:

$ module swap PE-intel PE-gnu
$ module swap gcc gcc/4.6.1
General Programming Environment Guidelines

We recommend the following general guidelines for using the programming environment modules:

  • Do not purge all modules; rather, use the default module environment provided at the time of login, and modify it.
  • Do not swap moab, torque, or MySQL modules after loading a programming environment modulefile.