This section describes some common issues encountered when configuring and compiling BOUT++, how to manually install dependencies if they are not available, and how to configure optional libraries like SUNDIALS and PETSc.

Optimisation and run-time checking¶

Configure with --enable-checks=3 enables a lot of checks of operations performed by the field objects. This is very useful for debugging a code, and can be omitted once bugs have been removed. --enable=checks=2 enables less checking, especially the computationally rather expensive ones, while --enable-checks=0 disables most checks.

To get most checking, both from BOUT++ and from the compiler --enable-debug can be used. That enables checks of level 3, as well as debug flags, e.g. -g for gcc.

For (sometimes) more useful error messages, there is the --enable-track option. This keeps track of the names of variables and includes these in error messages.

To enable optimization, configure with --enable-optimize=3. This will try to set appropriate flags, but may not set the best ones. This should work well for gcc. Similar to checks, different levels can be specified, where 3 is high, and 0 means disabling all optimization. --enable-optimize=fast will set the -Ofast flag for gcc which enables optimizations that are not standard conforming, so proceed at own risk.

Manually set compilation flags¶

You can set the following environment variables if you need more control over how BOUT++ is built:

• LDFLAGS: extra flags for linking, e.g. -L<library dir>
• LIBS: extra libraries for linking, e.g. -l<library>
• CPPFLAGS: preprocessor flags, e.g. -I<include dir>
• CXXFLAGS: compiler flags, e.g. -Wall
• SUNDIALS_EXTRA_LIBS specifies additional libraries for linking to SUNDIALS, which are put at the end of the link command.

It is possible to change flags for BOUT++ after running configure, by editing the make.config file. Note that this is not recommended, as e.g. PVODE will not be built with these flags.

Machine-specific installation¶

These are some configurations which have been found to work on particular machines.

Archer¶

As of 20th April 2018, the following configuration should work

$module swap PrgEnv-cray PrgEnv-gnu/5.1.29$ module load fftw
$module load archer-netcdf/4.1.3  When using CMake on Cray systems like Archer, you need to pass -DCMAKE_SYSTEM_NAME=CrayLinuxEnvironment so that the Cray compiler wrappers are detected properly. KNL @ Archer¶ To use the KNL system, configure BOUT++ as follows: ./configure MPICXX=CC --host=knl --with-netcdf --with-pnetcdf=no --with-hypre=no CXXFLAGS="-xMIC-AVX512 -D_GLIBCXX_USE_CXX11_ABI=0"  Atlas¶ ./configure --with-netcdf=/usr/local/tools/hdf5-gnu-serial-1.8.1/lib --with-fftw=/usr/local --with-pdb=/usr/gapps/pact/new/lnx-2.5-ib/gnu  Cab¶ ./configure --with-netcdf=/usr/local/tools/hdf5-gnu-serial-1.8.1/lib --with-fftw=/usr/local/tools/fftw3-3.2 --with-pdb=/usr/gapps/pact/new/lnx-2.5-ib/gnu  Edison¶ module swap PrgEnv-intel PrgEnv-gnu module load fftw ./configure MPICC=cc MPICXX=CC --with-netcdf=/global/u2/c/chma/PUBLIC/netcdf_edison/netcdf --with-fftw=/opt/fftw/3.3.0.1/x86_64  Hoffman2¶ ./configure --with-netcdf=/u/local/apps/netcdf/current --with-fftw=/u/local/apps/fftw3/current --with-cvode=/u/local/apps/sundials/2.4.0 --with-lapack=/u/local/apps/lapack/current  Hopper¶ module swap PrgEnv-pgi PrgEnv-gnu module load netcdf module swap netcdf netcdf/4.1.3 module swap gcc gcc/4.6.3 ./configure MPICC=cc MPICXX=CC --with-fftw=/opt/fftw/3.2.2.1 --with-pdb=/global/homes/u/umansky/PUBLIC/PACT_HOPP2/pact  Hyperion¶ With the bash shell use export PETSC_DIR=~farley9/projects/petsc/petsc-3.2-p1 export PETSC_ARCH=arch-c ./configure --with-netcdf=/usr/local/tools/netcdf-gnu-4.1 --with-fftw=/usr/local MPICXX=mpiCC EXTRA_LIBS=-lcurl --with-petsc --with-cvode=~farley9/local --with-ida=~farley9/local  With the tcsh shell use setenv PETSC_DIR ~farley9/projects/petsc/petsc-3.2-p1 setenv PETSC_ARCH arch-c ./configure --with-netcdf=/usr/local/tools/netcdf-gnu-4.1 --with-fftw=/usr/local MPICXX=mpiCC EXTRA_LIBS=-lcurl --with-petsc --with-cvode=~farley9/local --with-ida=~farley9/local  Marconi¶ module load intel intelmpi fftw lapack module load szip zlib/1.2.8--gnu--6.1.0 module load hdf5/1.8.17--intel--pe-xe-2017--binary module load netcdf-cxx4 module load python  To compile for the SKL partition, configure with ./configure --enable-checks=0 CPPFLAGS="-Ofast -funroll-loops -xCORE-AVX512 -mtune=skylake" --host skl  to enable AVX512 vectorization. Note As of 20/04/2018, an issue with the netcdf and netcdf-cxx4 modules means that you will need to remove -lnetcdf from EXTRA_LIBS in make.config after running ./configure and before running make. -lnetcdf needs also to be removed from bin/bout-config to allow a successful build of the python interface. Recreation of boutcore.pyx needs to be manually triggered, if boutcore.pyx has already been created. Ubgl¶ ./configure --with-netcdf CXXFLAGS=-DMPICH_IGNORE_CXX_SEEK CFLAGS=-DMPICH_IGNORE_CXX_SEEK --with-pdb=/usr/gapps/pact/new_s/lnx-2.5-ib --with-netcdf=/usr/local/tools/netcdf/netcdf-4.1_c++  File formats¶ BOUT++ can currently use two different file formats: NetCDF-4, and HDF5 and experimental support for parallel flavours of both. NetCDF is a widely used format and so has many more tools for viewing and manipulating files. In particular, the NetCDF-4 library can produce files in either NetCDF3 “classic” format, which is backwards-compatible with NetCDF libraries since 1994 (version 2.3), or in the newer NetCDF4 format, which is based on (and compatible with) HDF5. HDF5 is another widely used format. If you have multiple libraries installed then BOUT++ can use them simultaneously, for example reading in grid files in NetCDF format, but writing output data in HDF5 format. To enable NetCDF support, you will need to install NetCDF version 4.0.1 or later. Note that although the NetCDF-4 library is used for the C++ interface, by default BOUT++ writes the “classic” format. Because of this, you don’t need to install zlib or HDF5 for BOUT++ NetCDF support to work. If you want to output to HDF5 then you need to first install the zlib and HDF5 libraries, and then compile NetCDF with HDF5 support. When NetCDF is installed, a script nc-config should be put into somewhere on the path. If this is found then configure should have all the settings it needs. If this isn’t found then configure will search for the NetCDF include and library files. Installing NetCDF from source¶ The latest versions of NetCDF have separated out the C++ API from the main C library. As a result, you will need to download and install both. Download the latest versions of the NetCDF-C and NetCDF-4 C++ libraries from https://www.unidata.ucar.edu/downloads/netcdf. As of January 2017, these are versions 4.4.1.1 and 4.3.0 respectively. Untar the file and ’cd’ into the resulting directory: $ tar -xzvf netcdf-4.4.1.1.tar.gz
$cd netcdf-4.4.1.1  Then run configure, make and make install: $ ./configure --prefix=$HOME/local$ make
$make install  Sometimes configure can fail, in which case try disabling Fortran: $ ./configure --prefix=$HOME/local --disable-fortran$ make
$make install  Similarly for the C++ API: $ tar -xzvf netcdf-cxx4-4.3.0.tar.gz
$cd netcdf-cxx4-4.3.0$ ./configure --prefix=$HOME/local$ make
$make install  You may need to set a couple of environment variables as well: $ export PATH=$HOME/local/bin:$PATH
$export LD_LIBRARY_PATH=$HOME/local/lib:$LD_LIBRARY_PATH  You should check where NetCDF actually installed its libraries. On some systems this will be $HOME/local/lib, but on others it may be, e.g. $HOME/local/lib64. Check which it is, and set $LD_LIBRARY_PATH appropriately.

OpenMP¶

BOUT++ can make use of OpenMP parallelism. To enable OpenMP, use the --enable-openmp flag to configure:

./configure --enable-openmp


OpenMP can be used to parallelise in more directions than can be achieved with MPI alone. For example, it is currently difficult to parallelise in X using pure MPI if FCI is used, and impossible to parallelise at all in Z with pure MPI.

OpenMP is in a large number of places now, such that a decent speed-up can be achieved with OpenMP alone. Hybrid parallelisation with both MPI and OpenMP can lead to more significant speed-ups, but it sometimes requires some fine tuning of numerical parameters in order to achieve this. This greatly depends on the details not just of your system, but also your particular problem. We have tried to choose “sensible” defaults that will work well for the most common cases, but this is not always possible. You may need to perform some testing yourself to find e.g. the optimum split of OpenMP threads and MPI ranks.

One such parameter that can potentially have a significant effect (for some problem sizes on some machines) is setting the OpenMP schedule used in some of the OpenMP loops (specifically those using BOUT_FOR). This can be set using:

./configure --enable-openmp --with-openmp-schedule=<schedule>


with <schedule> being one of: static (the default), dynamic, guided, auto or runtime.

Note

If you want to use OpenMP with Clang, you will need Clang 3.7+, and either libomp or libiomp.

You will be able to compile BOUT++ with OpenMP with lower versions of Clang, or using the GNU OpenMP library libgomp, but it will only run with a single thread.

Note

By default PVODE is built without OpenMP support. To enable this add --enable-pvode-openmp to the configure command.

Note

OpenMP will attempt to use all available threads by default. This can cause oversubscription problems on certain systems. You can limit the number of threads OpenMP uses with the OMP_NUM_THREADS environment variable. See your system documentation for more details.

SUNDIALS¶

The BOUT++ distribution includes a 1998 version of CVODE (then called PVODE) by Scott D. Cohen and Alan C. Hindmarsh, which is the default time integration solver. Whilst no serious bugs have been found in this code (as far as the authors are aware of), several features such as user-supplied preconditioners and constraints cannot be used with this solver. Currently, BOUT++ also supports the SUNDIALS solvers CVODE, IDA and ARKODE which are available from https://computation.llnl.gov/casc/sundials/main.html.

Note

BOUT++ currently supports SUNDIALS > 2.6, up to 4.1.0 as of March 2019. It is advisable to use the highest possible version

In order for a smooth install it is recommended to install SUNDIALS from an install directory. The full installation guide is found in the downloaded .tar.gz, but we will provide a step-by-step guide to install it and make it compatible with BOUT++ here:

$cd ~$ mkdir -p install/sundials-install
$cd install/sundials-install$ # Move the downloaded sundials-4.1.0.tar.gz to sundials-install
$tar -xzvf sundials-4.1.0.tar.gz$ mkdir build && cd build

$cmake \ -DCMAKE_INSTALL_PREFIX=$HOME/local \
-DLAPACK_ENABLE=ON \
-DOPENMP_ENABLE=ON \
-DMPI_ENABLE=ON \
-DCMAKE_C_COMPILER=$(which mpicc) \ -DCMAKE_CXX_COMPILER=$(which mpicxx) \
../sundials-4.1.0

$make$ make test
$make install  The SUNDIALS IDA solver is a Differential-Algebraic Equation (DAE) solver, which evolves a system of the form $$\mathbf{f}(\mathbf{u},\dot{\mathbf{u}},t) = 0$$. This allows algebraic constraints on variables to be specified. To configure BOUT++ with SUNDIALS only (see section PETSc on how to build PETSc with SUNDIALS), go to the root directory of BOUT++ and type: $ ./configure --with-sundials=/path/to/sundials/install


SUNDIALS will allow you to select at run-time which solver to use. See Options for more details on how to do this.

PETSc¶

BOUT++ can use PETSc https://www.mcs.anl.gov/petsc/ for time-integration and for solving elliptic problems, such as inverting Poisson and Helmholtz equations.

Currently, BOUT++ supports PETSc versions 3.4 - 3.9. To install PETSc version 3.4.5, use the following steps:

$cd ~$ wget http://ftp.mcs.anl.gov/pub/petsc/release-snapshots/petsc-3.4.5.tar.gz
$tar -xzvf petsc-3.4.5.tar.gz$ # Optional
$# rm petsc-3.4.5.tar.gz$ cd petsc-3.4.5


To build PETSc without SUNDIALS, configure with:

$./configure \ --with-clanguage=cxx \ --with-mpi=yes \ --with-precision=double \ --with-scalar-type=real \ --with-shared-libraries=0  Add --with-debugging=yes to ./configure in order to allow debugging. Note To build PETSc with SUNDIALS, install SUNDIALS as explained in section SUNDIALS, and append ./configure with --with-sundials-dir=$HOME/local

Note

--download-mumps \


to ./configure.

To make PETSc, type:

$make PETSC_DIR=$HOME/petsc-3.4.5 PETSC_ARCH=arch-linux2-cxx-debug all


Should BLAS, LAPACK, or any other packages be missing, you will get an error, and a suggestion that you can append --download-name-of-package to the ./configure line. You may want to test that everything is configured properly. To do this, type:

$make PETSC_DIR=$HOME/petsc-3.4.5 PETSC_ARCH=arch-linux2-cxx-debug test


To use PETSc, you have to define the PETSC_DIR and PETSC_ARCH environment variables to match how PETSc was built:

$export PETSC_DIR=$HOME/petsc-3.4.5
$export PETSC_ARCH=arch-linux2-cxx-debug  and add to your startup file $HOME/.bashrc:

export PETSC_DIR=$HOME/petsc-3.4.5 export PETSC_ARCH=arch-linux2-cxx-debug  To configure BOUT++ with PETSc, go to the BOUT++ root directory, and type: $ ./configure --with-petsc


You can configure BOUT++ against different PETSc installations either through the PETSC_DIR/ARCH variables as above, or by specifying them on the command line:

$./configure --with-petsc PETSC_DIR=/path/to/other/petsc PETSC_ARCH=other-arch  Note Unfortunately, there are a variety of ways PETSc can be installed on a system, and it is hard to automatically work out how to compile against a particular installation. In particular, there are two PETSc-supported ways of installing PETSc that are subtly different. The first way is as above, using PETSC_DIR and PETSC_ARCH. A second way is to use the --prefix argument to configure (much like the traditional GNU configure scripts) when building PETSc. In this case, PETSC_DIR will be the path passed to --prefix and PETSC_ARCH will be empty. When configuring BOUT++, one can use --with-petsc=$PETSC_DIR as a shortcut in this case. This will NOT work if PETSc was installed with a PETSC_ARCH.

However, there are at least some Linux distributions that install PETSc in yet another way and you may need to set PETSC_DIR/ARCH differently. For example, for Fedora, as of May 2018, you will need to configure and build BOUT++ like so:

$./configure --with-petsc=/usr/lib64/openmpi$ PETSC_DIR=/usr make


Replace openmpi with the correct MPI implementation that you have installed.

LAPACK¶

BOUT++ comes with linear solvers for tridiagonal and band-diagonal systems. Some implementations of these solvers (for example Laplacian inversion, section Laplacian inversion) use LAPACK for efficient serial performance. This does not add new features, but may be faster in some cases. LAPACK is however written in FORTRAN 77, which can cause linking headaches. To enable these routines use:

$./configure --with-lapack  and to specify a non-standard path: $ ./configure --with-lapack=/path/to/lapack


MUMPS¶

This is still experimental, but does work on at least some systems at York. The PETSc library can be used to call MUMPS for directly solving matrices (e.g. for Laplacian inversions), or MUMPS can be used directly. To enable MUMPS, configure with:

$./configure --with-mumps  MUMPS has many dependencies, including ScaLapack and ParMetis. Unfortunately, the exact dependencies and configuration of MUMPS varies a lot from system to system. The easiest way to get MUMPS installed is to install PETSc with MUMPS, or supply the CPPFLAGS, LDFLAGS and LIBS environment variables to configure: $ ./configure --with-mumps CPPFLAGS=-I/path/to/mumps/includes \
LDFLAGS=-L/path/to/mumps/libs \
LIBS="-ldmumps -lmumps_common -lother_libs_needed_for_mumps"


MPI compilers¶

These are usually called something like mpicc and mpiCC (or mpicxx), and the configure script will look for several common names. If your compilers aren’t recognised then set them using:

$./configure MPICC=<your C compiler> MPICXX=<your C++ compiler>  NOTES: • On LLNL’s Grendel, mpicxx is broken. Use mpiCC instead by passing “MPICXX=mpiCC” to configure. Also need to specify this to NetCDF library by passing “CXX=mpiCC” to NetCDF configure. Installing MPICH from source¶ In your home directory, create two subdirectories: One called “install” where we’ll put the source code, and one called “local” where we’ll install the MPI compiler: $ cd
$mkdir install$ mkdir local


Download the latest stable version of MPICH from https://www.mpich.org/ and put the file in the “install” subdirectory created above. At the time of writing (January 2018), the file was called mpich-3.2.1.tar.gz. Untar the file:

$tar -xzvf mpich-3.2.1.tar.gz  which will create a directory containing the source code. ’cd’ into this directory and run: $ ./configure --prefix=$HOME/local$ make
$make install  Each of which might take a while. This is the standard way of installing software from source, and will also be used for installing libraries later. The –prefix= option specifies where the software should be installed. Since we don’t have permission to write in the system directories (e.g. /usr/bin), we just use a subdirectory of our home directory. The configure command configures the install, finding the libraries and commands it needs. make compiles everything using the options found by configure. The final make install step copies the compiled code into the correct places under $HOME/local.

To be able to use the MPI compiler, you need to modify the PATH environment variable. To do this, run:

$export PATH=$PATH:$HOME/local/bin  and add this to the end of your startup file $HOME/.bashrc. If you’re using CSH rather than BASH, the command is:

% setenv PATH ${PATH}:${HOME}/local/bin


and the startup file is $HOME/.cshrc. You should now be able to run mpicc and so have a working MPI compiler. Installing FFTW from source¶ If you haven’t already, create directories “install” and “local” in your home directory: $ cd
$mkdir install$ mkdir local


Download the latest stable version from http://www.fftw.org/download.html into the “install” directory. At the time of writing, this was called fftw-3.3.2.tar.gz. Untar this file, and ’cd’ into the resulting directory. As with the MPI compiler, configure and install the FFTW library into $HOME/local by running: $ ./configure --prefix=$HOME/local$ make
$make install  Compiling and running under AIX¶ Most development and running of BOUT++ is done under Linux, with the occasional FreeBSD and OSX. The configuration scripts are therefore heavily tested on these architectures. IBM’s POWER architecture however runs AIX, which has some crucial differences which make compiling a pain. • Under Linux/BSD, it’s usual for a Fortran routine foo to appear under C as foo_, whilst under AIX the name is unchanged • MPI compiler scripts are usually given the names mpicc and either mpiCC or mpicxx. AIX uses mpcc and mpCC. • Like BSD, the make command isn’t compatible with GNU make, so you have to run gmake to compile everything. • The POWER architecture is big-endian, different to the little endian Intel and AMD chips. This can cause problems with binary file formats. SUNDIALS under AIX¶ To compile SUNDIALS, use: export CC=cc export CXX=xlC export F77=xlf export OBJECT_MODE=64 ./configure --prefix=$HOME/local/ --with-mpicc=mpcc --with-mpif77=mpxlf CFLAGS=-maix64


You may get an error message like

make: Not a recognized flag: w


This is because the AIX make is being used, rather than gmake. The easiest way to fix this is to make a link to gmake in your local bin directory

ln -s /usr/bin/gmake $HOME/local/bin/make  Running which make should now point to this local/bin/make, and if not then you need to make sure that your bin directory appears first in the PATH export PATH=$HOME/local/bin:$PATH  If you see an error like this ar: 0707-126 ../../src/sundials/sundials_math.o is not valid with the current object file mode. Use the -X option to specify the desired object mode.  then you need to set the environment variable OBJECT_MODE export OBJECT_MODE=64  Configuring BOUT++, you may get the error configure: error: C compiler cannot create executables  In that case, you can try using: ./configure CFLAGS="-maix64"  When compiling, you may see warnings: xlC_r: 1501-216 (W) command option -64 is not recognized - passed to ld  At this point, the main BOUT++ library should compile, and you can try compiling one of the examples. ld: 0711-317 ERROR: Undefined symbol: .NcError::NcError(NcError::Behavior) ld: 0711-317 ERROR: Undefined symbol: .NcFile::is_valid() const ld: 0711-317 ERROR: Undefined symbol: .NcError::~NcError() ld: 0711-317 ERROR: Undefined symbol: .NcFile::get_dim(const char*) const  This is probably because the NetCDF libraries are 32-bit, whilst BOUT++ has been compiled as 64-bit. You can try compiling BOUT++ as 32-bit export OBJECT_MODE=32 ./configure CFLAGS="-maix32" gmake  If you still get undefined symbols, then go back to 64-bit, and edit make.config, replacing -lnetcdf_c++ with -lnetcdf64_c++, and -lnetcdf with -lnetcdf64. This can be done by running sed 's/netcdf/netcdf64/g' make.config > make.config.new mv make.config.new make.config  Issues¶ Wrong install script¶ Before installing, make sure the correct version of install is being used by running: $ which install


This should point to a system directory like /usr/bin/install. Sometimes when IDL has been installed, this points to the IDL install (e.g. something like /usr/common/usg/idl/idl70/bin/install on Franklin). A quick way to fix this is to create a link from your local bin to the system install:

$ln -s /usr/bin/install$HOME/local/bin/


“which install” should now print the install in your local bin directory.

Compiling cvode.cxx fails¶

Occasionally compiling the CVODE solver interface will fail with an error similar to:

cvode.cxx: In member function ‘virtual int CvodeSolver::init(rhsfunc, bool, int, BoutR...
cvode.cxx:234:56: error: invalid conversion from ‘int (*)(CVINT...
...


This is caused by different sizes of ints used in different versions of the CVODE library. The configure script tries to determine the correct type to use, but may fail in unusual circumstances. To fix, edit src/solver/impls/cvode/cvode.cxx, and change line 48 from

typedef int CVODEINT;


to

typedef long CVODEINT;


Compiling with IBM xlC compiler fails¶

When using the xlC compiler, an error may occur:

variant.hpp(1568) parameter pack "Ts" was referenced but not expanded


The workaround is to change line 428 of externalpackages/mpark.variant/include/mpark/lib.hpp from:

#ifdef MPARK_TYPE_PACK_ELEMENT


to:

#ifdef CAUSES_ERROR // MPARK_TYPE_PACK_ELEMENT


This will force an alternate implementation of type_pack_element to be defined. See also https://software.intel.com/en-us/forums/intel-c-compiler/topic/501502