Building PISM¶

To make sure that the key PETSc and MPI prerequisites work properly together, so that you can run PISM in parallel, you might want to make sure that the correct mpiexec can be found, by setting your PATH. For instance, if you used the option --download-mpich=1 in the PETSc configure, the MPI bin directory will have a path like $PETSC_DIR/$PETSC_ARCH/bin. Thus the following lines might appear in your .bashrc or .profile, if not there already:

export PETSC_DIR=/home/user/petsc-3.10.2/
export PETSC_ARCH=opt
export PATH=$PETSC_DIR/$PETSC_ARCH/bin/:$PATH

From now on we will assume that the PETSC_ARCH and PETSC_DIR variables are set.

Note

The PETSC_ARCH variable is not needed if PETSc was configured using the --prefix= option.

Follow these steps to build PISM:

Get the latest source for PISM using the Git version control system by running
```
git clone https://github.com/pism/pism.git pism-stable
```
A directory called “pism-stable” will be created. Note that in the future when you enter that directory, git pull will update to the latest revision of PISM. 1

Note

You can also download a tarball from GitHub.
Build PISM:2
```
mkdir -p pism-stable/build
cd pism-stable/build
export CC=mpicc
export CXX=mpicxx
cmake -DCMAKE_INSTALL_PREFIX=~/pism ..
make -j install
```
Here pism-stable is the directory containing PISM source code while ~/pism is the directory PISM will be installed into.

Variables CC and CXX specify MPI compiler wrappers provided by your MPI installation.

Note

When using MPI’s compiler wrappers, make sure that mpicc and mpicxx you select were used to compile the PETSc library: PISM and PETSc have to use the same MPI installation.

Commands above will configure PISM to be installed in ~/pism/bin and ~/pism/lib/ then compile and install all its executables and scripts.

If your operating system does not support shared libraries3, then set Pism_LINK_STATICALLY to “ON”. This can be done by either running
```
cmake -DPism_LINK_STATICALLY=ON ..
```
or by using ccmake4 run
```
ccmake ..
```
and then change Pism_LINK_STATICALLY (and then press c to “configure” and g to “generate Makefiles”). Then run make install.

Temporary files created during the build process (located in the build sub-directory) are not automatically deleted after installing PISM, so run “make clean” if space is an issue. You can also delete the build directory altogether if you are not planning on re-compiling PISM.
Note

When using Intel’s compiler and high optimization settings such as -O3, -fp-model precise may be needed to get reproducible model results. Set it using ccmake or by setting CFLAGS and CXXFLAGS environment variables when building PISM’s prerequisites (such as PETSc) and PISM itself.
```
export CFLAGS="-fp-model precise"
export CXXFLAGS="-fp-model precise"
cmake [other options] ..
```
Note

To achieve best performance it can be useful to tell the compiler to target the “native” architecture. (This gives it permission to use CPU instructions that may not work on older CPUs.)
```
export CFLAGS="-march=native"
export CXXFLAGS="-march=native"
cmake [other options] ..
```
PISM executables can be run most easily by adding the bin/ sub-directory in your selected install path (~/pism/bin in the example above) to your PATH. For instance, this command can be done in the Bash shell or in your .bashrc file:
```
export PATH=~/pism/bin:$PATH
```
Now see section Quick tests of the installation or Getting started: a Greenland ice sheet example to continue.

PISM’s build-time configuration¶

Some of PISM’s features (the ones requiring additional libraries, for example) need to be enabled when building PISM. This section lists important build-time options.

Option	Description
`CMAKE_BUILD_TYPE`	"build type": set to "Debug" for development
`BUILD_SHARED_LIBS`	build shared (as opposed to static) libraries (this is the default)
`Pism_LINK_STATICALLY`	set CMake flags to try to ensure that everything is linked statically
`Pism_LOOK_FOR_LIBRARIES`	specifies whether PISM should look for libraries (disable this on Crays)
`Pism_BUILD_EXTRA_EXECS`	build additional executables (needed to run `make test`)
`Pism_BUILD_PYTHON_BINDINGS`	build PISM’s Python bindingd; requires `petsc4py`
`Pism_USE_PROJ`	use the PROJ library to compute latitudes and longitudes of grid points
`Pism_USE_PIO`	use the ParallelIO library to write output files
`Pism_USE_PARALLEL_NETCDF4`	use NetCDF for parallel file I/O
`Pism_USE_PNETCDF`	use PnetCDF for parallel file I/O
`Pism_DEBUG`	enables extra sanity checks in the code (this makes PISM a lot slower but simplifies development)

To enable PISM’s use of PROJ, for example, run

cmake -DPism_USE_PROJ [other options] ..

Building PISM with libraries in non-standard locations¶

To build PISM with libraries installed in a non-standard location such as ~/local/, use CMake’s variable CMAKE_FIND_ROOT_PATH. Set it to a semicolon-separated list of directories.

For example, if netcdf.h is located in ~/local/netcdf/include/ and libnetcdf.so is in ~/local/netcdf/lib, add ~/local/netcdf to CMAKE_FIND_ROOT_PATH:

cmake -DCMAKE_FIND_ROOT_PATH=~/local/netcdf [other options] ..

To build PISM using parallel I/O libraries installed as described in Installing parallel I/O libraries, do this:

cmake -DCMAKE_FIND_ROOT_PATH="~/local/netcdf;~/local/pnetcdf;~/local/parallelio" \
      -DPism_USE_PNETCDF \
      -DPism_USE_PARALLEL_NETCDF4 \
      -DPism_USE_PIO \
      ..

Footnotes

1: Of course, after git pull you will make -C build install to recompile and re-install PISM.
2: Please report any problems you meet at these build stages by sending us the output.
3: This might be necessary if you’re building on a Cray XT5 or a Sun Opteron Cluster, for example.
4: Install the cmake-curses-gui package to get ccmake on Ubuntu.