Compiling applications in Mahti
- Whenever possible, use the local disk on the login node for compiling software.
- Compiling on the local disk is much faster and shifts load from the shared file system.
- The local disk is cleaned frequently, so please move your files elsewhere after compiling.
Building MPI applications
module load clang
and Intel compilers with the command:
module load intel
Different applications function better with different suites, so the selection needs to be done on a case-by-case basis.
The MPI environment in Mahti is OpenMPI, and when building MPI
applications all compiler suites can be used with
mpicxx (C++), or
mpif90 (Fortran) wrappers.
The compiler options for different suites are different. The recommended basic optimization flags are listed in the table below. It is recommended to start from the safe level and then move up to intermediate or even aggressive, while making sure the results are correct and the program's performance has improved.
|Optimisation level||GNU||Intel||AMD (clang)|
|Safe||-O2 -march=native||-O2 -fp-model precise||-O2 -march=native|
|Intermediate||-O3 -march=native||-O2||-O3 -march=native|
|Aggressive||-O3 -march=native -ffast-math -funroll-loops||-O3 -fp-model fast=2 -no-prec-div -fimf-use-svml=true||-O3 -march=native -ffast-math -funroll-loops|
A detailed list of options for the Intel and GNU compilers can be found on the man
man icc/ifort) when the corresponding programming
environment is loaded, or in the compiler manuals (see the links above).
List all available versions of the compiler suites:
module spider gcc module spider clang module spider intel
Building OpenMP and hybrid applications
Additional compiler and linker flags are needed when building OpenMP or MPI/OpenMP hybrid applications:
|Compiler suite||OpenMP flag|
|GNU and AMD||-fopenmp|
Building serial applications
For building serial applications, one needs to use compiler suite specific compiler command:
Last edited Wed Aug 26 2020