Add flexible solver and preconditioner infrastructure.

Also use it in flow_blackoil_dunecpr.cpp. Adds new command-line parameter,
--linear-solver-configuration-json-file, to read linear solver config from
JSON-format file at runtime.

.clang-format

@@ -0,0 +1,20 @@
+{
+        BasedOnStyle: WebKit,
+        AlignAfterOpenBracket: AlwaysBreak,
+        AlignConsecutiveAssignments: false,
+        AlignConsecutiveDeclarations: false,
+        AlignAfterOpenBracket: Align,
+        AllowShortBlocksOnASingleLine: false,
+        AllowShortFunctionsOnASingleLine: None,
+        AlwaysBreakAfterReturnType: TopLevelDefinitions,
+        AlwaysBreakTemplateDeclarations: Yes,
+        BinPackArguments: false,
+        BinPackParameters: false,
+        BreakBeforeBraces: Linux,
+        BreakConstructorInitializers: BeforeComma,
+        ColumnLimit: 120,
+        Cpp11BracedListStyle: true,
+        FixNamespaceComments: true,
+        MaxEmptyLinesToKeep: 5,
+        NamespaceIndentation: Inner,
+}

CMakeLists_files.cmake

@@ -37,6 +37,7 @@ list (APPEND MAIN_SOURCE_FILES
   opm/core/wells/well_controls.c
   opm/core/wells/wells.c
   opm/simulators/linalg/ExtractParallelGridInformationToISTL.cpp
+  opm/simulators/linalg/setupPropertyTree.cpp
   opm/simulators/timestepping/TimeStepControl.cpp
   opm/simulators/timestepping/AdaptiveSimulatorTimer.cpp
   opm/simulators/timestepping/SimulatorTimer.cpp
@@ -55,6 +56,7 @@ list (APPEND TEST_SOURCE_FILES
   tests/test_ecl_output.cc
   tests/test_blackoil_amg.cpp
   tests/test_convergencereport.cpp
+  tests/test_flexiblesolver.cpp
   tests/test_graphcoloring.cpp
   tests/test_vfpproperties.cpp
   tests/test_milu.cpp
@@ -110,6 +112,9 @@ list (APPEND TEST_DATA_FILES
   tests/relpermDiagnostics.DATA
   tests/norne_pvt.data
   tests/wells_no_perforation.data
+  tests/matr33.txt
+  tests/rhs3.txt
+  tests/options_flexiblesolver.json
   )
 
 
@@ -155,14 +160,23 @@ list (APPEND PUBLIC_HEADER_FILES
   opm/simulators/linalg/twolevelmethodcpr.hh
   opm/simulators/linalg/CPRPreconditioner.hpp
   opm/simulators/linalg/ExtractParallelGridInformationToISTL.hpp
+  opm/simulators/linalg/FlexibleSolver.hpp
   opm/simulators/linalg/FlowLinearSolverParameters.hpp
+  opm/simulators/linalg/GetQuasiImpesWeights.hpp
   opm/simulators/linalg/GraphColoring.hpp
   opm/simulators/linalg/ISTLSolverEbos.hpp
   opm/simulators/linalg/ISTLSolverEbosCpr.hpp
+  opm/simulators/linalg/ISTLSolverEbosFlexible.hpp
   opm/simulators/linalg/MatrixBlock.hpp
+  opm/simulators/linalg/MatrixMarketUtils.hpp
+  opm/simulators/linalg/OwningTwolevelPreconditioner.hpp
   opm/simulators/linalg/ParallelOverlappingILU0.hpp
   opm/simulators/linalg/ParallelRestrictedAdditiveSchwarz.hpp
   opm/simulators/linalg/ParallelIstlInformation.hpp
+  opm/simulators/linalg/PressureSolverPolicy.hpp
+  opm/simulators/linalg/PressureTransferPolicy.hpp
+  opm/simulators/linalg/makePreconditioner.hpp
+  opm/simulators/linalg/setupPropertyTree.hpp
   opm/simulators/timestepping/AdaptiveSimulatorTimer.hpp
   opm/simulators/timestepping/AdaptiveTimeSteppingEbos.hpp
   opm/simulators/timestepping/ConvergenceReport.hpp

flow/flow_blackoil_dunecpr.cpp

@@ -1,5 +1,5 @@
 /*
-  Copyright 2013, 2014, 2015 SINTEF ICT, Applied Mathematics.
+  Copyright 2013, 2014, 2015, 2019 SINTEF Digital, Mathematics and Cybernetics.
   Copyright 2014 Dr. Blatt - HPC-Simulation-Software & Services
   Copyright 2015, 2017 IRIS AS
 
@@ -21,7 +21,7 @@
 #include "config.h"
 #include "flow/flow_tag.hpp"
 //#include <opm/linearsolvers/amgclsolverbackend.hh>
-#include  <opm/simulators/linalg/ISTLSolverEbosCpr.hpp>
+#include  <opm/simulators/linalg/ISTLSolverEbosFlexible.hpp>
 //#include <ewoms/linear/superlubackend.hh>
 
 BEGIN_PROPERTIES
@@ -48,8 +48,8 @@ SET_PROP(EclFlowProblemSimple, FluidState)
 
 SET_BOOL_PROP(EclFlowProblemSimple,MatrixAddWellContributions,true);
 SET_INT_PROP(EclFlowProblemSimple,LinearSolverVerbosity,0);
-SET_SCALAR_PROP(EclFlowProblemSimple, LinearSolverReduction, 1e-4);
-SET_INT_PROP(EclFlowProblemSimple, LinearSolverMaxIter, 20);
+SET_SCALAR_PROP(EclFlowProblemSimple, LinearSolverReduction, 1e-2);
+SET_INT_PROP(EclFlowProblemSimple, LinearSolverMaxIter, 100);
 SET_BOOL_PROP(EclFlowProblemSimple, UseAmg, true);//probably not used
 SET_BOOL_PROP(EclFlowProblemSimple, UseCpr, true);
 SET_INT_PROP(EclFlowProblemSimple, CprMaxEllIter, 1);
@@ -79,7 +79,7 @@ namespace Ewoms {
     //SET_TYPE_PROP(EclFlowProblemSimple, LinearSolverBackend, Ewoms::Linear::ParallelBiCGStabSolverBackend<TypeTag>);//not work
     //SET_TYPE_PROP(EclFlowProblemSimple, LinearSolverBackend, Ewoms::Linear::SuperLUBackend<TypeTag>)//not work
     //SET_TAG_PROP(EclFlowProblem, FluidState, Opm::BlackOilFluidState);
-    SET_TYPE_PROP(EclFlowProblemSimple, LinearSolverBackend, Opm::ISTLSolverEbosCpr<TypeTag>);
+    SET_TYPE_PROP(EclFlowProblemSimple, LinearSolverBackend, Opm::ISTLSolverEbosFlexible<TypeTag>);
     SET_BOOL_PROP(EclFlowProblemSimple, EnableStorageCache, true);
     SET_BOOL_PROP(EclFlowProblemSimple, EnableIntensiveQuantityCache, true);
     

opm/simulators/linalg/FlexibleSolver.hpp

@@ -0,0 +1,115 @@
+/*
+  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef OPM_FLEXIBLE_SOLVER_HEADER_INCLUDED
+#define OPM_FLEXIBLE_SOLVER_HEADER_INCLUDED
+
+#include <opm/simulators/linalg/makePreconditioner.hpp>
+
+#include <dune/common/fmatrix.hh>
+#include <dune/istl/bcrsmatrix.hh>
+#include <dune/istl/solvers.hh>
+#include <dune/istl/umfpack.hh>
+
+#include <boost/property_tree/ptree.hpp>
+
+namespace Dune
+{
+
+
+
+template <class MatrixTypeT, class VectorTypeT>
+class FlexibleSolver : Dune::InverseOperator<VectorTypeT, VectorTypeT>
+{
+public:
+    using MatrixType = MatrixTypeT;
+    using VectorType = VectorTypeT;
+
+    FlexibleSolver(const boost::property_tree::ptree& prm, const MatrixType& matrix)
+    {
+        makeSolver(prm, matrix);
+    }
+
+    virtual void apply(VectorType& x, VectorType& rhs, Dune::InverseOperatorResult& res) override
+    {
+        linsolver_->apply(x, rhs, res);
+    }
+
+    virtual void apply(VectorType& x, VectorType& rhs, double reduction, Dune::InverseOperatorResult& res) override
+    {
+        linsolver_->apply(x, rhs, reduction, res);
+    }
+
+    virtual Dune::SolverCategory::Category category() const override
+    {
+        return Dune::SolverCategory::sequential;
+    }
+
+private:
+    void makeSolver(const boost::property_tree::ptree& prm, const MatrixType& matrix)
+    {
+        const double tol = prm.get<double>("tol");
+        const int maxiter = prm.get<int>("maxiter");
+        linearoperator_.reset(new Dune::MatrixAdapter<MatrixType, VectorType, VectorType>(matrix));
+        preconditioner_ = Dune::makePreconditioner<MatrixType, VectorType>(*linearoperator_, prm);
+        int verbosity = prm.get<int>("verbosity");
+        std::string solver_type = prm.get<std::string>("solver");
+        if (solver_type == "bicgstab") {
+            linsolver_.reset(new Dune::BiCGSTABSolver<VectorType>(*linearoperator_,
+                                                                  *preconditioner_,
+                                                                  tol, // desired residual reduction factor
+                                                                  maxiter, // maximum number of iterations
+                                                                  verbosity));
+        } else if (solver_type == "loopsolver") {
+            linsolver_.reset(new Dune::LoopSolver<VectorType>(*linearoperator_,
+                                                              *preconditioner_,
+                                                              tol, // desired residual reduction factor
+                                                              maxiter, // maximum number of iterations
+                                                              verbosity));
+        } else if (solver_type == "gmres") {
+            int restart = prm.get<int>("restart");
+            linsolver_.reset(new Dune::RestartedGMResSolver<VectorType>(*linearoperator_,
+                                                                        *preconditioner_,
+                                                                        tol,
+                                                                        restart, // desired residual reduction factor
+                                                                        maxiter, // maximum number of iterations
+                                                                        verbosity));
+#if HAVE_SUITESPARSE_UMFPACK
+        } else if (solver_type == "umfpack") {
+            bool dummy = false;
+            linsolver_.reset(new Dune::UMFPack<MatrixType>(linearoperator_->getmat(), verbosity, dummy));
+#endif
+        } else {
+            std::string msg("Solver not known ");
+            msg += solver_type;
+            throw std::runtime_error(msg);
+        }
+    }
+
+    std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>> preconditioner_;
+    std::shared_ptr<Dune::MatrixAdapter<MatrixType, VectorType, VectorType>> linearoperator_;
+    std::shared_ptr<Dune::InverseOperator<VectorType, VectorType>> linsolver_;
+};
+
+} // namespace Dune
+
+
+
+#endif // OPM_FLEXIBLE_SOLVER_HEADER_INCLUDED

opm/simulators/linalg/FlowLinearSolverParameters.hpp

@@ -66,6 +66,7 @@ NEW_PROP_TAG(CprUseDrs);
 NEW_PROP_TAG(CprMaxEllIter);
 NEW_PROP_TAG(CprEllSolvetype);
 NEW_PROP_TAG(CprReuseSetup);
+NEW_PROP_TAG(LinearSolverConfigurationJsonFile);
 
 SET_SCALAR_PROP(FlowIstlSolverParams, LinearSolverReduction, 1e-2);
 SET_SCALAR_PROP(FlowIstlSolverParams, IluRelaxation, 0.9);
@@ -90,6 +91,7 @@ SET_BOOL_PROP(FlowIstlSolverParams, CprUseDrs, false);
 SET_INT_PROP(FlowIstlSolverParams, CprMaxEllIter, 20);
 SET_INT_PROP(FlowIstlSolverParams, CprEllSolvetype, 0);
 SET_INT_PROP(FlowIstlSolverParams, CprReuseSetup, 0);
+SET_STRING_PROP(FlowIstlSolverParams, LinearSolverConfigurationJsonFile, "none");
 
 
 
@@ -160,6 +162,7 @@ namespace Opm
         bool   use_cpr_;
         std::string system_strategy_;
         bool scale_linear_system_;
+        std::string linear_solver_configuration_json_file_;
 
         template <class TypeTag>
         void init()
@@ -186,6 +189,7 @@ namespace Opm
             cpr_max_ell_iter_  =  EWOMS_GET_PARAM(TypeTag, int, CprMaxEllIter);
             cpr_ell_solvetype_  =  EWOMS_GET_PARAM(TypeTag, int, CprEllSolvetype);
             cpr_reuse_setup_  =  EWOMS_GET_PARAM(TypeTag, int, CprReuseSetup);
+            linear_solver_configuration_json_file_ = EWOMS_GET_PARAM(TypeTag, std::string, LinearSolverConfigurationJsonFile);
         }
 
         template <class TypeTag>
@@ -212,6 +216,7 @@ namespace Opm
             EWOMS_REGISTER_PARAM(TypeTag, int, CprMaxEllIter, "MaxIterations of the elliptic pressure part of the cpr solver");
             EWOMS_REGISTER_PARAM(TypeTag, int, CprEllSolvetype, "Solver type of elliptic pressure solve (0: bicgstab, 1: cg, 2: only amg preconditioner)");
             EWOMS_REGISTER_PARAM(TypeTag, int, CprReuseSetup, "Reuse Amg Setup");
+            EWOMS_REGISTER_PARAM(TypeTag, std::string, LinearSolverConfigurationJsonFile, "Filename of JSON configuration for flexible linear solver system.");
         }
 
         FlowLinearSolverParameters() { reset(); }

opm/simulators/linalg/ISTLSolverEbosFlexible.hpp

@@ -0,0 +1,125 @@
+/*
+  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef OPM_ISTLSOLVEREBOSFLEXIBLE_HEADER_INCLUDED
+#define OPM_ISTLSOLVEREBOSFLEXIBLE_HEADER_INCLUDED
+
+#include <ewoms/linear/matrixblock.hh>
+#include <opm/simulators/linalg/FlexibleSolver.hpp>
+#include <opm/simulators/linalg/setupPropertyTree.hpp>
+
+#include <memory>
+#include <utility>
+
+BEGIN_PROPERTIES
+
+NEW_TYPE_TAG(FlowIstlSolverFlexible, INHERITS_FROM(FlowIstlSolverParams));
+
+NEW_PROP_TAG(LinearSolverConfiguration);
+NEW_PROP_TAG(GlobalEqVector);
+NEW_PROP_TAG(SparseMatrixAdapter);
+NEW_PROP_TAG(Simulator);
+
+END_PROPERTIES
+
+
+namespace Opm
+{
+
+//=====================================================================
+// Implementation for ISTL-matrix based operator
+//=====================================================================
+/// This class solves the fully implicit black-oil system by
+/// solving the reduced system (after eliminating well variables)
+/// as a block-structured matrix (one block for all cell variables) for a fixed
+/// number of cell variables.
+///
+/// The solvers and preconditioners used are run-time configurable.
+template <class TypeTag>
+class ISTLSolverEbosFlexible
+{
+    using SparseMatrixAdapter = typename GET_PROP_TYPE(TypeTag, SparseMatrixAdapter);
+    using VectorType = typename GET_PROP_TYPE(TypeTag, GlobalEqVector);
+    using Simulator = typename GET_PROP_TYPE(TypeTag, Simulator);
+    using MatrixType = typename SparseMatrixAdapter::IstlMatrix;
+    using POrComm = Dune::Amg::SequentialInformation;
+    using MatrixAdapterType = Dune::MatrixAdapter<MatrixType, VectorType, VectorType>;
+    using SolverType = Dune::FlexibleSolver<MatrixType, VectorType>;
+
+public:
+    static void registerParameters()
+    {
+        FlowLinearSolverParameters::registerParameters<TypeTag>();
+    }
+
+    explicit ISTLSolverEbosFlexible(const Simulator& simulator)
+        : simulator_(simulator)
+    {
+        parameters_.template init<TypeTag>();
+    }
+
+    void eraseMatrix()
+    {
+    }
+
+    void prepare(const SparseMatrixAdapter& mat, VectorType& b)
+    {
+        boost::property_tree::ptree prm = setupPropertyTree(parameters_);
+        solver_.reset(new SolverType(prm, mat.istlMatrix()));
+        rhs_ = b;
+    }
+
+    bool solve(VectorType& x)
+    {
+        solver_->apply(x, rhs_, res_);
+        return res_.converged;
+    }
+
+    bool isParallel()
+    {
+        return false;
+    }
+
+    int iterations() const
+    {
+        return res_.iterations;
+    }
+
+    void setResidual(VectorType& /* b */)
+    {
+        // rhs_ = &b; // Must be handled in prepare() instead.
+    }
+
+    void setMatrix(const SparseMatrixAdapter& /* M */)
+    {
+        // matrix_ = &M.istlMatrix(); // Must be handled in prepare() instead.
+    }
+
+protected:
+    const Simulator& simulator_;
+
+    std::unique_ptr<SolverType> solver_;
+    FlowLinearSolverParameters parameters_;
+    VectorType rhs_;
+    Dune::InverseOperatorResult res_;
+}; // end ISTLSolverEbosFlexible
+
+} // namespace Opm
+
+#endif // OPM_ISTLSOLVEREBOSFLEXIBLE_HEADER_INCLUDED

opm/simulators/linalg/MatrixMarketUtils.hpp

@@ -0,0 +1,100 @@
+/*
+  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.
+  Copyright 2019 Dr. Blatt - HPC-Simulation-Software & Services.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef OPM_MATRIXMARKETUTILS_HEADER_INCLUDED
+#define OPM_MATRIXMARKETUTILS_HEADER_INCLUDED
+
+#include <dune/istl/matrixmarket.hh>
+#include <cstddef>
+
+namespace Dune
+{
+
+namespace MatrixMarketImpl
+{
+    template <typename T, typename A, int brows, int bcols, typename D>
+    void makeSparseEntries(Dune::BCRSMatrix<Dune::FieldMatrix<T, brows, bcols>, A>& matrix,
+                           std::vector<int>& i,
+                           std::vector<int>& j,
+                           std::vector<double>& val,
+                           const D&)
+    {
+        // addapted from readSparseEntries
+        typedef Dune::BCRSMatrix<Dune::FieldMatrix<T, brows, bcols>, A> Matrix;
+        std::vector<std::set<IndexData<D>>> rows(matrix.N() * brows);
+        for (std::size_t kk = 0; kk < i.size(); ++kk) {
+            std::size_t row;
+            IndexData<D> data;
+            row = i[kk];
+            assert(row / bcols < matrix.N());
+            data.number = val[kk];
+            data.index = j[kk];
+            assert(data.index / bcols < matrix.M());
+            rows[row].insert(data);
+        }
+
+        // Setup the matrix sparsity pattern
+        int nnz = 0;
+        for (typename Matrix::CreateIterator iter = matrix.createbegin(); iter != matrix.createend(); ++iter) {
+            for (std::size_t brow = iter.index() * brows, browend = iter.index() * brows + brows; brow < browend;
+                 ++brow) {
+                typedef typename std::set<IndexData<D>>::const_iterator Siter;
+                for (Siter siter = rows[brow].begin(), send = rows[brow].end(); siter != send; ++siter, ++nnz)
+                    iter.insert(siter->index / bcols);
+            }
+        }
+
+        // Set the matrix values
+        matrix = 0;
+
+        MatrixValuesSetter<D, brows, bcols> Setter;
+
+        Setter(rows, matrix);
+    }
+} // end namespace MatrixMarketImpl
+
+
+template <typename T, typename A, int brows, int bcols>
+void
+makeMatrixMarket(Dune::BCRSMatrix<Dune::FieldMatrix<T, brows, bcols>, A>& matrix,
+                 std::vector<int> i,
+                 std::vector<int> j,
+                 std::vector<T> val,
+                 size_t rows,
+                 size_t cols)
+{
+    // addapted from readMatrixMarket
+    using namespace MatrixMarketImpl;
+    // std::size_t rows, cols, entries;
+    // std::size_t nnz, blockrows, blockcols;
+    // std::tie(blockrows, blockcols, nnz) = calculateNNZ<brows, bcols>(rows, cols, entries, header);
+    std::size_t blockrows = rows / brows;
+    std::size_t blockcols = cols / bcols;
+    matrix.setSize(blockrows, blockcols);
+    matrix.setBuildMode(Dune::BCRSMatrix<Dune::FieldMatrix<T, brows, bcols>, A>::row_wise);
+    makeSparseEntries(matrix, i, j, val, NumericWrapper<T>());
+}
+
+
+} // end namespace Dune
+
+
+
+#endif // OPM_MATRIXMARKETUTILS_HEADER_INCLUDED

opm/simulators/linalg/OwningTwoLevelPreconditioner.hpp

@@ -0,0 +1,123 @@
+/*
+  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef OPM_OWNINGTWOLEVELPRECONDITIONER_HEADER_INCLUDED
+#define OPM_OWNINGTWOLEVELPRECONDITIONER_HEADER_INCLUDED
+
+#include <opm/simulators/linalg/PressureSolverPolicy.hpp>
+#include <opm/simulators/linalg/PressureTransferPolicy.hpp>
+#include <opm/simulators/linalg/getQuasiImpesWeights.hpp>
+
+#include <dune/common/fmatrix.hh>
+#include <dune/istl/bcrsmatrix.hh>
+#include <dune/istl/paamg/amg.hh>
+
+#include <boost/property_tree/ptree.hpp>
+
+#include <fstream>
+
+namespace Dune
+{
+
+// Circular dependency between makePreconditioner() [which can make an OwningTwoLevelPreconditioner]
+// and OwningTwoLevelPreconditioner [which uses makePreconditioner() to choose the fine-level smoother]
+// must be broken, accomplished by forward-declaration here.
+template <class MatrixType, class VectorType>
+std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>>
+makePreconditioner(const Dune::MatrixAdapter<MatrixType, VectorType, VectorType>& linearoperator,
+                   const boost::property_tree::ptree& prm);
+
+// Must forward-declare FlexibleSolver as we want to use it as solver for the pressure system.
+template <class MatrixTypeT, class VectorTypeT>
+class FlexibleSolver;
+
+template <class MatrixTypeT, class VectorTypeT, bool transpose = false>
+class OwningTwoLevelPreconditioner : public Dune::Preconditioner<VectorTypeT, VectorTypeT>
+{
+public:
+    using pt = boost::property_tree::ptree;
+    using MatrixType = MatrixTypeT;
+    using VectorType = VectorTypeT;
+    using OperatorType = Dune::MatrixAdapter<MatrixType, VectorType, VectorType>;
+
+    OwningTwoLevelPreconditioner(OperatorType& linearoperator, pt& prm)
+        : finesmoother_(makePreconditioner<MatrixType, VectorType>(linearoperator, prm.get_child("finesmoother")))
+        , comm_()
+        , weights_(Opm::Amg::getQuasiImpesWeights<MatrixType, VectorType>(
+              linearoperator.getmat(), prm.get<int>("pressure_var_index"), transpose))
+        , levelTransferPolicy_(comm_, weights_, prm.get<int>("pressure_var_index"))
+        , coarseSolverPolicy_(prm.get_child("coarsesolver"))
+        , twolevel_method_(linearoperator,
+                           finesmoother_,
+                           levelTransferPolicy_,
+                           coarseSolverPolicy_,
+                           transpose ? 1 : 0,
+                           transpose ? 0 : 1)
+    {
+        if (prm.get<int>("verbosity") > 10) {
+            std::ofstream outfile(prm.get<std::string>("weights_filename"));
+            if (!outfile) {
+                throw std::runtime_error("Could not write weights");
+            }
+            Dune::writeMatrixMarket(weights_, outfile);
+        }
+    }
+
+    virtual void pre(VectorType& x, VectorType& b) override
+    {
+        twolevel_method_.pre(x, b);
+    }
+    virtual void apply(VectorType& v, const VectorType& d) override
+    {
+        twolevel_method_.apply(v, d);
+    }
+    virtual void post(VectorType& x) override
+    {
+        twolevel_method_.post(x);
+    }
+    virtual Dune::SolverCategory::Category category() const override
+    {
+        return Dune::SolverCategory::sequential;
+    }
+
+private:
+    using PressureMatrixType = Dune::BCRSMatrix<Dune::FieldMatrix<double, 1, 1>>;
+    using PressureVectorType = Dune::BlockVector<Dune::FieldVector<double, 1>>;
+    using CoarseOperatorType = Dune::MatrixAdapter<PressureMatrixType, PressureVectorType, PressureVectorType>;
+    using Communication = Dune::Amg::SequentialInformation;
+    using LevelTransferPolicy = Opm::PressureTransferPolicy<OperatorType, CoarseOperatorType, Communication, transpose>;
+    using CoarseSolverPolicy
+        = Dune::Amg::PressureSolverPolicy<CoarseOperatorType, FlexibleSolver<PressureMatrixType, PressureVectorType>>;
+    using TwoLevelMethod
+        = Dune::Amg::TwoLevelMethod<OperatorType, CoarseSolverPolicy, Dune::Preconditioner<VectorType, VectorType>>;
+
+    std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>> finesmoother_;
+    Communication comm_;
+    VectorType weights_;
+    LevelTransferPolicy levelTransferPolicy_;
+    CoarseSolverPolicy coarseSolverPolicy_;
+    TwoLevelMethod twolevel_method_;
+};
+
+} // namespace Dune
+
+
+
+
+#endif // OPM_OWNINGTWOLEVELPRECONDITIONER_HEADER_INCLUDED

opm/simulators/linalg/PressureSolverPolicy.hpp

@@ -0,0 +1,114 @@
+/*
+  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef OPM_PRESSURE_SOLVER_POLICY_HEADER_INCLUDED
+#define OPM_PRESSURE_SOLVER_POLICY_HEADER_INCLUDED
+
+#include <boost/property_tree/ptree.hpp>
+
+#include <dune/istl/solver.hh>
+
+namespace Dune
+{
+namespace Amg
+{
+    namespace pt = boost::property_tree;
+
+    template <class OperatorType, class Solver>
+    class PressureSolverPolicy
+    {
+    public:
+        /** @brief The type of the linear operator used. */
+        using Operator = OperatorType;
+        /**
+         * @brief Constructs the coarse solver policy.
+         * @param prm Parameter tree specifying the solver details.
+         */
+        explicit PressureSolverPolicy(const pt::ptree prm)
+            : prm_(prm)
+        {
+        }
+
+    private:
+        using X = typename Operator::range_type;
+        /**
+         * @brief A wrapper that makes an inverse operator out of AMG.
+         *
+         * The operator will use one step of AMG to approximately solve
+         * the coarse level system.
+         */
+        struct PressureInverseOperator : public Dune::InverseOperator<X, X> {
+            PressureInverseOperator(Operator& op, const boost::property_tree::ptree& prm)
+                : linsolver_()
+            {
+                linsolver_.reset(new Solver(prm, op.getmat()));
+            }
+
+            Dune::SolverCategory::Category category() const override
+            {
+                return Dune::SolverCategory::sequential;
+            }
+
+            void apply(X& x, X& b, double reduction, Dune::InverseOperatorResult& res) override
+            {
+                linsolver_->apply(x, b, reduction, res);
+            }
+
+            void apply(X& x, X& b, Dune::InverseOperatorResult& res) override
+            {
+                linsolver_->apply(x, b, res);
+            }
+
+        private:
+            std::shared_ptr<Solver> linsolver_;
+        };
+
+    public:
+        /** @brief The type of solver constructed for the coarse level. */
+        using CoarseLevelSolver = PressureInverseOperator;
+
+        /**
+         * @brief Constructs a coarse level solver.
+         *
+         * @param transferPolicy The policy describing the transfer between levels.
+         * @return A pointer to the constructed coarse level solver.
+         */
+        template <class LTP>
+        void setCoarseOperator(LTP& transferPolicy)
+        {
+            coarseOperator_ = transferPolicy.getCoarseLevelOperator();
+        }
+        template <class LTP>
+        CoarseLevelSolver* createCoarseLevelSolver(LTP& transferPolicy)
+        {
+            coarseOperator_ = transferPolicy.getCoarseLevelOperator();
+            PressureInverseOperator* inv = new PressureInverseOperator(*coarseOperator_, prm_);
+            return inv;
+        }
+
+    private:
+        /** @brief The coarse level operator. */
+        std::shared_ptr<Operator> coarseOperator_;
+        pt::ptree prm_;
+    };
+} // namespace Amg
+} // namespace Dune
+
+
+#endif // OPM_PRESSURE_SOLVER_POLICY_HEADER_INCLUDED

opm/simulators/linalg/PressureTransferPolicy.hpp

@@ -0,0 +1,158 @@
+/*
+  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.
+  Copyright 2019 Dr. Blatt - HPC-Simulation-Software & Services.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef OPM_PRESSURE_TRANSFER_POLICY_HEADER_INCLUDED
+#define OPM_PRESSURE_TRANSFER_POLICY_HEADER_INCLUDED
+
+
+#include <dune/istl/paamg/twolevelmethod.hh>
+
+
+namespace Opm
+{
+
+template <class FineOperator, class CoarseOperator, class Communication, bool transpose = false>
+class PressureTransferPolicy : public Dune::Amg::LevelTransferPolicy<FineOperator, CoarseOperator>
+{
+public:
+    typedef Dune::Amg::LevelTransferPolicy<FineOperator, CoarseOperator> FatherType;
+    typedef Communication ParallelInformation;
+    typedef typename FineOperator::domain_type FineVectorType;
+
+public:
+    PressureTransferPolicy(const Communication& comm, const FineVectorType& weights, int pressure_var_index)
+        : communication_(&const_cast<Communication&>(comm))
+        , weights_(weights)
+        , pressure_var_index_(pressure_var_index)
+    {
+    }
+
+    void createCoarseLevelSystem(const FineOperator& fineOperator)
+    {
+        using CoarseMatrix = typename CoarseOperator::matrix_type;
+        const auto& fineLevelMatrix = fineOperator.getmat();
+        coarseLevelMatrix_.reset(new CoarseMatrix(fineLevelMatrix.N(), fineLevelMatrix.M(), CoarseMatrix::row_wise));
+        auto createIter = coarseLevelMatrix_->createbegin();
+
+        for (const auto& row : fineLevelMatrix) {
+            for (auto col = row.begin(), cend = row.end(); col != cend; ++col) {
+                createIter.insert(col.index());
+            }
+            ++createIter;
+        }
+
+        calculateCoarseEntries(fineOperator);
+        coarseLevelCommunication_.reset(communication_, [](Communication*) {});
+
+        this->lhs_.resize(this->coarseLevelMatrix_->M());
+        this->rhs_.resize(this->coarseLevelMatrix_->N());
+        using OperatorArgs = typename Dune::Amg::ConstructionTraits<CoarseOperator>::Arguments;
+        OperatorArgs oargs(*coarseLevelMatrix_, *coarseLevelCommunication_);
+        this->operator_.reset(Dune::Amg::ConstructionTraits<CoarseOperator>::construct(oargs));
+    }
+
+    void calculateCoarseEntries(const FineOperator& fineOperator)
+    {
+        const auto& fineMatrix = fineOperator.getmat();
+        *coarseLevelMatrix_ = 0;
+        auto rowCoarse = coarseLevelMatrix_->begin();
+        for (auto row = fineMatrix.begin(), rowEnd = fineMatrix.end(); row != rowEnd; ++row, ++rowCoarse) {
+            assert(row.index() == rowCoarse.index());
+            auto entryCoarse = rowCoarse->begin();
+            for (auto entry = row->begin(), entryEnd = row->end(); entry != entryEnd; ++entry, ++entryCoarse) {
+                assert(entry.index() == entryCoarse.index());
+                double matrix_el = 0;
+                if (transpose) {
+                    auto bw = weights_[entry.index()];
+                    for (size_t i = 0; i < bw.size(); ++i) {
+                        matrix_el += (*entry)[pressure_var_index_][i] * bw[i];
+                    }
+                } else {
+                    auto bw = weights_[row.index()];
+                    for (size_t i = 0; i < bw.size(); ++i) {
+                        matrix_el += (*entry)[i][pressure_var_index_] * bw[i];
+                    }
+                }
+                (*entryCoarse) = matrix_el;
+            }
+        }
+        assert(rowCoarse == coarseLevelMatrix_->end());
+    }
+
+    void moveToCoarseLevel(const typename FatherType::FineRangeType& fine)
+    {
+        // Set coarse vector to zero
+        this->rhs_ = 0;
+
+        auto end = fine.end(), begin = fine.begin();
+
+        for (auto block = begin; block != end; ++block) {
+            auto bw = weights_[block.index()];
+            double rhs_el = 0.0;
+            if (transpose) {
+                rhs_el = (*block)[pressure_var_index_];
+            } else {
+                for (size_t i = 0; i < block->size(); ++i) {
+                    rhs_el += (*block)[i] * bw[i];
+                }
+            }
+            this->rhs_[block - begin] = rhs_el;
+        }
+
+        this->lhs_ = 0;
+    }
+
+    void moveToFineLevel(typename FatherType::FineDomainType& fine)
+    {
+        auto end = fine.end(), begin = fine.begin();
+
+        for (auto block = begin; block != end; ++block) {
+            if (transpose) {
+                auto bw = weights_[block.index()];
+                for (size_t i = 0; i < block->size(); ++i) {
+                    (*block)[i] = this->lhs_[block - begin] * bw[i];
+                }
+            } else {
+                (*block)[pressure_var_index_] = this->lhs_[block - begin];
+            }
+        }
+    }
+
+    PressureTransferPolicy* clone() const
+    {
+        return new PressureTransferPolicy(*this);
+    }
+
+    const Communication& getCoarseLevelCommunication() const
+    {
+        return *coarseLevelCommunication_;
+    }
+
+private:
+    Communication* communication_;
+    const FineVectorType& weights_;
+    const int pressure_var_index_;
+    std::shared_ptr<Communication> coarseLevelCommunication_;
+    std::shared_ptr<typename CoarseOperator::matrix_type> coarseLevelMatrix_;
+};
+
+} // namespace Opm
+
+#endif // OPM_PRESSURE_TRANSFER_POLICY_HEADER_INCLUDED

opm/simulators/linalg/getQuasiImpesWeights.hpp

@@ -0,0 +1,90 @@
+/*
+  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef OPM_GET_QUASI_IMPES_WEIGHTS_HEADER_INCLUDED
+#define OPM_GET_QUASI_IMPES_WEIGHTS_HEADER_INCLUDED
+
+#include <algorithm>
+#include <cmath>
+
+namespace Opm
+{
+
+namespace Details
+{
+    template <class DenseMatrix>
+    DenseMatrix transposeDenseMatrix(const DenseMatrix& M)
+    {
+        DenseMatrix tmp;
+        for (int i = 0; i < M.rows; ++i)
+            for (int j = 0; j < M.cols; ++j)
+                tmp[j][i] = M[i][j];
+
+        return tmp;
+    }
+} // namespace Details
+
+namespace Amg
+{
+    template <class Matrix, class Vector>
+    void getQuasiImpesWeights(const Matrix& matrix, const int pressureVarIndex, Vector& weights, bool transpose = false)
+    {
+        using VectorBlockType = typename Vector::block_type;
+        using MatrixBlockType = typename Matrix::block_type;
+        const Matrix& A = matrix;
+        VectorBlockType rhs(0.0);
+        rhs[pressureVarIndex] = 1.0;
+        const auto endi = A.end();
+        for (auto i = A.begin(); i != endi; ++i) {
+            const auto endj = (*i).end();
+            MatrixBlockType diag_block(0.0);
+            for (auto j = (*i).begin(); j != endj; ++j) {
+                if (i.index() == j.index()) {
+                    diag_block = (*j);
+                    break;
+                }
+            }
+            VectorBlockType bweights;
+            if (transpose) {
+                diag_block.solve(bweights, rhs);
+            } else {
+                auto diag_block_transpose = Opm::Details::transposeDenseMatrix(diag_block);
+                diag_block_transpose.solve(bweights, rhs);
+            }
+            double abs_max = *std::max_element(
+                bweights.begin(), bweights.end(), [](double a, double b) { return std::fabs(a) < std::fabs(b); });
+            bweights /= std::fabs(abs_max);
+            weights[i.index()] = bweights;
+        }
+        // return weights;
+    }
+
+    template <class Matrix, class Vector>
+    Vector getQuasiImpesWeights(const Matrix& matrix, const int pressureVarIndex, bool transpose = false)
+    {
+        Vector weights(matrix.N());
+        getQuasiImpesWeights(matrix, pressureVarIndex, weights, transpose);
+        return weights;
+    }
+
+} // namespace Amg
+
+} // namespace Opm
+
+#endif // OPM_GET_QUASI_IMPES_WEIGHTS_HEADER_INCLUDED

opm/simulators/linalg/makePreconditioner.hpp

@@ -0,0 +1,193 @@
+/*
+  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef OPM_MAKEPRECONDITIONER_HEADER_INCLUDED
+#define OPM_MAKEPRECONDITIONER_HEADER_INCLUDED
+
+#include <opm/simulators/linalg/OwningTwoLevelPreconditioner.hpp>
+#include <opm/simulators/linalg/ParallelOverlappingILU0.hpp>
+
+#include <dune/istl/paamg/amg.hh>
+#include <dune/istl/paamg/fastamg.hh>
+#include <dune/istl/preconditioners.hh>
+
+#include <boost/property_tree/ptree.hpp>
+
+namespace Dune
+{
+
+template <class MatrixType, class VectorType>
+std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>>
+makeSeqPreconditioner(const Dune::MatrixAdapter<MatrixType, VectorType, VectorType>& linearoperator,
+                      const boost::property_tree::ptree& prm)
+{
+    auto& matrix = linearoperator.getmat();
+    std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>> preconditioner;
+    double w = prm.get<double>("w");
+    int n = prm.get<int>("n");
+    std::string precond(prm.get<std::string>("preconditioner"));
+    if (precond == "ILU0") {
+        preconditioner.reset(new Dune::SeqILU0<MatrixType, VectorType, VectorType>(matrix, w));
+    } else if (precond == "ParOverILU0") {
+        preconditioner.reset(new Opm::ParallelOverlappingILU0<MatrixType, VectorType, VectorType>(matrix, n, w, Opm::MILU_VARIANT::ILU));
+    } else if (precond == "Jac") {
+        preconditioner.reset(new Dune::SeqJac<MatrixType, VectorType, VectorType>(matrix, n, w));
+    } else if (precond == "GS") {
+        preconditioner.reset(new Dune::SeqGS<MatrixType, VectorType, VectorType>(matrix, n, w));
+    } else if (precond == "SOR") {
+        preconditioner.reset(new Dune::SeqSOR<MatrixType, VectorType, VectorType>(matrix, n, w));
+    } else if (precond == "SSOR") {
+        preconditioner.reset(new Dune::SeqSSOR<MatrixType, VectorType, VectorType>(matrix, n, w));
+    } else if (precond == "ILUn") {
+        preconditioner.reset(new Dune::SeqILUn<MatrixType, VectorType, VectorType>(matrix, n, w));
+    } else {
+        std::string msg("No such seq preconditioner : ");
+        msg += precond;
+        throw std::runtime_error(msg);
+    }
+    return preconditioner;
+}
+
+template <class Smoother, class MatrixType, class VectorType>
+std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>>
+makeAmgPreconditioner(Dune::MatrixAdapter<MatrixType, VectorType, VectorType>& linearoperator,
+                      const boost::property_tree::ptree& global_prm)
+{
+    boost::property_tree::ptree prm = global_prm.get_child("amg");
+    typedef Dune::MatrixAdapter<MatrixType, VectorType, VectorType> OperatorType;
+    std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>> preconditioner;
+    typedef Dune::Amg::AggregationCriterion<Dune::Amg::SymmetricMatrixDependency<MatrixType, Dune::Amg::FirstDiagonal>>
+        CriterionBase;
+    typedef Dune::Amg::CoarsenCriterion<CriterionBase> Criterion;
+    int coarsenTarget = prm.get<int>("coarsenTarget");
+    int ml = prm.get<int>("maxlevel");
+    Criterion criterion(15, coarsenTarget);
+    criterion.setDefaultValuesIsotropic(2);
+    criterion.setAlpha(prm.get<double>("alpha"));
+    criterion.setBeta(prm.get<double>("beta"));
+    criterion.setMaxLevel(ml);
+    criterion.setSkipIsolated(false);
+    criterion.setDebugLevel(prm.get<int>("verbosity"));
+    if (global_prm.get<std::string>("preconditioner") == "famg") {
+        Dune::Amg::Parameters parms;
+        parms.setNoPreSmoothSteps(1);
+        parms.setNoPostSmoothSteps(1);
+        preconditioner.reset(new Dune::Amg::FastAMG<OperatorType, VectorType>(linearoperator, criterion, parms));
+    } else {
+        typedef typename Dune::Amg::SmootherTraits<Smoother>::Arguments SmootherArgs;
+        SmootherArgs smootherArgs;
+        smootherArgs.iterations = prm.get<int>("n");
+        // smootherArgs.overlap=SmootherArgs::vertex;
+        // smootherArgs.overlap=SmootherArgs::none;
+        // smootherArgs.overlap=SmootherArgs::aggregate;
+        smootherArgs.relaxationFactor = prm.get<double>("w");
+        preconditioner.reset(
+            new Dune::Amg::AMG<OperatorType, VectorType, Smoother>(linearoperator, criterion, smootherArgs));
+    }
+    return preconditioner;
+}
+
+
+
+
+template <class MatrixType, class VectorType>
+std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>>
+makeAmgPreconditioners(Dune::MatrixAdapter<MatrixType, VectorType, VectorType>& linearoperator,
+                       const boost::property_tree::ptree& prm)
+{
+    std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>> preconditioner;
+    if (prm.get<std::string>("preconditioner") == "famg") {
+        // smoother type should not be used
+        preconditioner
+            = makeAmgPreconditioner<Dune::SeqILU0<MatrixType, VectorType, VectorType>, MatrixType, VectorType>(
+                linearoperator, prm);
+        return preconditioner;
+    }
+
+    std::string precond = prm.get<std::string>("amg.smoother");
+    if (precond == "ILU0") {
+        preconditioner
+            = makeAmgPreconditioner<Dune::SeqILU0<MatrixType, VectorType, VectorType>, MatrixType, VectorType>(
+                linearoperator, prm);
+    } else if (precond == "Jac") {
+        preconditioner
+            = makeAmgPreconditioner<Dune::SeqJac<MatrixType, VectorType, VectorType>, MatrixType, VectorType>(
+                linearoperator, prm);
+        // }else if(precond == "GS"){
+        //   preconditioner = makeAmgPreconditioner<
+        // 	Dune::SeqGS<MatrixType, VectorType, VectorType>,
+        // 	MatrixType, VectorType>(linearoperator,prm);
+    } else if (precond == "SOR") {
+        preconditioner
+            = makeAmgPreconditioner<Dune::SeqSOR<MatrixType, VectorType, VectorType>, MatrixType, VectorType>(
+                linearoperator, prm);
+    } else if (precond == "SSOR") {
+        preconditioner
+            = makeAmgPreconditioner<Dune::SeqSSOR<MatrixType, VectorType, VectorType>, MatrixType, VectorType>(
+                linearoperator, prm);
+    } else if (precond == "ILUn") {
+        preconditioner
+            = makeAmgPreconditioner<Dune::SeqILUn<MatrixType, VectorType, VectorType>, MatrixType, VectorType>(
+                linearoperator, prm);
+    } else {
+        std::string msg("No such seq preconditioner : ");
+        msg += precond;
+        throw std::runtime_error(msg);
+    }
+    return preconditioner;
+}
+
+template <class MatrixType, class VectorType>
+std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>>
+makeTwoLevelPreconditioner(Dune::MatrixAdapter<MatrixType, VectorType, VectorType>& linearoperator,
+                           const boost::property_tree::ptree& global_prm)
+{
+    boost::property_tree::ptree prm = global_prm.get_child("cpr");
+    std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>> preconditioner;
+    if (global_prm.get<std::string>("preconditioner") == "cpr") {
+        preconditioner.reset(new OwningTwoLevelPreconditioner<MatrixType, VectorType, false>(linearoperator, prm));
+    } else if (global_prm.get<std::string>("preconditioner") == "cprt") {
+        preconditioner.reset(new OwningTwoLevelPreconditioner<MatrixType, VectorType, true>(linearoperator, prm));
+    } else {
+        std::string msg("Wrong cpr Should not happen");
+        throw std::runtime_error(msg);
+    }
+    return preconditioner;
+}
+
+template <class MatrixType, class VectorType>
+std::shared_ptr<Dune::Preconditioner<VectorType, VectorType>>
+makePreconditioner(Dune::MatrixAdapter<MatrixType, VectorType, VectorType>& linearoperator,
+                   const boost::property_tree::ptree& prm)
+{
+    if ((prm.get<std::string>("preconditioner") == "famg") or (prm.get<std::string>("preconditioner") == "amg")) {
+        return makeAmgPreconditioners<MatrixType, VectorType>(linearoperator, prm);
+    } else if ((prm.get<std::string>("preconditioner") == "cpr")
+               or (prm.get<std::string>("preconditioner") == "cprt")) {
+        return makeTwoLevelPreconditioner<MatrixType, VectorType>(linearoperator, prm);
+    } else {
+        return makeSeqPreconditioner<MatrixType, VectorType>(linearoperator, prm);
+    }
+}
+
+
+} // namespace Dune
+
+
+#endif // OPM_MAKEPRECONDITIONER_HEADER_INCLUDED

opm/simulators/linalg/setupPropertyTree.cpp

@@ -0,0 +1,115 @@
+/*
+  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <opm/simulators/linalg/setupPropertyTree.hpp>
+
+#include <boost/property_tree/json_parser.hpp>
+
+namespace Opm
+{
+
+boost::property_tree::ptree setupPropertyTree(const FlowLinearSolverParameters& p)
+{
+    boost::property_tree::ptree prm;
+    if (p.linear_solver_configuration_json_file_ != "none") {
+        boost::property_tree::read_json(p.linear_solver_configuration_json_file_, prm);
+    } else {
+        prm.put("tol", p.linear_solver_reduction_);
+        prm.put("maxiter", p.linear_solver_maxiter_);
+        prm.put("verbosity", p.linear_solver_verbosity_);
+        prm.put("preconditioner", "ILU0");
+        prm.put("solver", "bicgstab");
+        prm.put("w", 1.0);
+        prm.put("n", 1);
+    }
+
+    /*
+    prm.put("tol", 0.5);
+    prm.put("maxiter", 20);
+    prm.put("preconditioner", "cpr");
+    prm.put("w", 1);
+    prm.put("n", 1);
+    prm.put("cpr.finesmoother.preconditioner", "ILU0");
+    prm.put("cpr.finesmoother.w", 1);
+    prm.put("cpr.finesmoother.n", 1);
+    prm.put("cpr.coarsesolver.tol", 0.5);
+    prm.put("cpr.coarsesolver.maxiter", 20);
+    prm.put("cpr.coarsesolver.preconditioner", "amg");
+    prm.put("cpr.coarsesolver.amg.maxlevel", 5);
+    prm.put("cpr.coarsesolver.amg.coarsenTarget", 1000);
+    prm.put("cpr.coarsesolver.amg.smoother", "ILU0");
+    prm.put("cpr.coarsesolver.amg.alpha", 0.2);
+    prm.put("cpr.coarsesolver.amg.beta", 0.0001);
+    prm.put("cpr.coarsesolver.amg.verbosity", 0);
+    prm.put("cpr.coarsesolver.amg.n", 1);
+    prm.put("cpr.coarsesolver.amg.w", 1);
+    prm.put("cpr.coarsesolver.verbosity", 0);
+    prm.put("cpr.coarsesolver.solver", "bicgstab");
+    prm.put("cpr.verbosity", 11);
+    prm.put("cpr.weights_filename" , "weight_cpr.txt");
+    prm.put("cpr.pressure_var_index" , 1);
+    prm.put("verbosity", 10);
+    prm.put("solver", "bicgstab");
+    prm.put("restart", 20);
+    */
+
+    return prm;
+}
+
+} // namespace Opm
+/*
+{
+    "tol": "0.5",
+    "maxiter": "20",
+    "preconditioner": "cpr",
+    "w": "1",
+    "n": "1",
+    "amg": "",
+    "cpr": {
+        "finesmoother": {
+            "preconditioner": "ILU0",
+            "w": "1",
+            "n": "1"
+        },
+        "coarsesolver": {
+            "tol": "0.5",
+            "maxiter": "20",
+            "preconditioner": "amg",
+            "amg": {
+                "maxlevel": "5",
+                "coarsenTarget": "1000",
+                "smoother": "ILU0",
+                "alpha": "0.2",
+                "beta": "0.0001",
+                "verbosity": "0",
+                "n": "1",
+                "w": "1"
+            },
+            "verbosity": "0",
+            "solver": "bicgstab"
+        },
+        "verbosity": "11",
+        "weights_filename" : "weight_cpr.txt",
+        "pressure_var_index" : "1"
+    },
+    "verbosity": "10",
+    "solver": "bicgstab",
+    "restart": "20"
+}
+*/

opm/simulators/linalg/setupPropertyTree.hpp

@@ -0,0 +1,34 @@
+/*
+  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef OPM_SETUPPROPERTYTREE_HEADER_INCLUDED
+#define OPM_SETUPPROPERTYTREE_HEADER_INCLUDED
+
+#include <opm/simulators/linalg/FlowLinearSolverParameters.hpp>
+
+#include <boost/property_tree/ptree.hpp>
+
+namespace Opm
+{
+
+boost::property_tree::ptree setupPropertyTree(const FlowLinearSolverParameters& p);
+
+} // namespace Opm
+
+#endif // OPM_SETUPPROPERTYTREE_HEADER_INCLUDED

tests/matr33.txt

@@ -0,0 +1,66 @@
+%%MatrixMarket matrix coordinate real general
+% ISTL_STRUCT blocked 3 3
+9 9 63
+1 1 1.63148e-07
+1 2 0.126774
+1 3 -6.09774e-05
+2 1 4.64465e-10
+2 2 -0.0987407
+2 3 -5.86038e-05
+3 1 5.66966e-08
+3 2 -12.0531
+3 3 0.0462478
+1 4 -8.84841e-11
+1 5 -5.64705e-05
+1 6 0
+2 4 -3.93176e-10
+2 5 0
+2 6 0
+3 4 -4.79944e-08
+3 5 0
+3 6 0
+4 1 -8.89921e-11
+4 2 -0.00786145
+4 3 0
+5 1 -3.53139e-10
+5 2 0.0283977
+5 3 -3.79289e-05
+6 1 -4.31072e-08
+6 2 3.46646
+6 3 -0.00944335
+4 4 1.20862e-10
+4 5 0.0829656
+4 6 0
+5 4 7.40377e-10
+5 5 -0.0929483
+5 6 -0.0967963
+6 4 4.64141e-07
+6 5 -9.10276
+6 6 16.3772
+4 7 -2.168e-11
+4 8 -1.38362e-05
+4 9 0
+5 7 -7.8331e-10
+5 8 0
+5 9 0
+6 7 -1.20687e-07
+6 8 0
+6 9 0
+7 4 -2.17548e-11
+7 5 -0.00183118
+7 6 0
+8 4 -8.00212e-10
+8 5 0.0276779
+8 6 0.0320899
+9 4 -1.56667e-07
+9 5 2.7106
+9 6 -7.32919
+7 7 4.43266e-09
+7 8 0.0744616
+7 9 0
+8 7 1.59375e-07
+8 8 -0.0899451
+8 9 -0.0940009
+9 7 2.86852e-05
+9 8 -5.63337
+9 9 13.3423

tests/options_flexiblesolver.json

@@ -0,0 +1,38 @@
+{
+    "tol": "0.5",
+    "maxiter": "20",
+    "preconditioner": "cpr",
+    "w": "1",
+    "n": "1",
+    "amg": "",
+    "cpr": {
+        "finesmoother": {
+            "preconditioner": "ILU0",
+            "w": "1",
+            "n": "1"
+        },
+        "coarsesolver": {
+            "tol": "0.5",
+            "maxiter": "20",
+            "preconditioner": "amg",
+            "amg": {
+                "maxlevel": "5",
+                "coarsenTarget": "1000",
+                "smoother": "ILU0",
+                "alpha": "0.2",
+                "beta": "0.0001",
+                "verbosity": "0",
+                "n": "1",
+                "w": "1"
+            },
+            "verbosity": "0",
+            "solver": "bicgstab"
+        },
+        "verbosity": "11",
+        "weights_filename" : "weight_cpr.txt",
+        "pressure_var_index" : "1"
+    },
+    "verbosity": "10",
+    "solver": "bicgstab",
+    "restart": "20"
+}

tests/rhs3.txt

@@ -0,0 +1,12 @@
+%%MatrixMarket matrix array real general
+% ISTL_STRUCT blocked 3 1
+9 1
+-4.48332e-07
+3.53746e-07
+4.31812e-05
+1.48051e-07
+-5.76325e-07
+-0.000243496
+-3.81652e-08
+1.21761e-06
+-9.97615e-05

tests/test_flexiblesolver.cpp

@@ -0,0 +1,108 @@
+/*
+  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <config.h>
+
+#define BOOST_TEST_MODULE OPM_test_FlexibleSolver
+#include <boost/test/unit_test.hpp>
+
+#include <boost/property_tree/json_parser.hpp>
+#include <boost/property_tree/ptree.hpp>
+#include <fstream>
+#include <iostream>
+#include <opm/simulators/linalg/FlexibleSolver.hpp>
+
+
+template <int bz>
+Dune::BlockVector<Dune::FieldVector<double, bz>>
+testSolver(const boost::property_tree::ptree& prm, const std::string& matrix_filename, const std::string& rhs_filename)
+{
+    using Matrix = Dune::BCRSMatrix<Dune::FieldMatrix<double, bz, bz>>;
+    using Vector = Dune::BlockVector<Dune::FieldVector<double, bz>>;
+    Matrix matrix;
+    {
+        std::ifstream mfile(matrix_filename);
+        if (!mfile) {
+            throw std::runtime_error("Could not read matrix file");
+        }
+        readMatrixMarket(matrix, mfile);
+    }
+    Vector rhs;
+    {
+        std::ifstream rhsfile(rhs_filename);
+        if (!rhsfile) {
+            throw std::runtime_error("Could not read rhs file");
+        }
+        readMatrixMarket(rhs, rhsfile);
+    }
+    Dune::FlexibleSolver<Matrix, Vector> solver(prm, matrix);
+    Vector x(rhs.size());
+    Dune::InverseOperatorResult res;
+    solver.apply(x, rhs, res);
+    return x;
+}
+
+BOOST_AUTO_TEST_CASE(TestFlexibleSolver)
+{
+    namespace pt = boost::property_tree;
+    pt::ptree prm;
+
+    // Read parameters.
+    {
+        std::ifstream file("options_flexiblesolver.json");
+        pt::read_json(file, prm);
+        // pt::write_json(std::cout, prm);
+    }
+
+    // Test with 1x1 block solvers.
+    {
+        const int bz = 1;
+        auto sol = testSolver<bz>(prm, "matr33.txt", "rhs3.txt");
+        Dune::BlockVector<Dune::FieldVector<double, bz>> expected {-1.62493,
+                                                                   -1.76435e-06,
+                                                                   1.86991e-10,
+                                                                   -458.542,
+                                                                   2.28308e-06,
+                                                                   -2.45341e-07,
+                                                                   -1.48005,
+                                                                   -5.02264e-07,
+                                                                   -1.049e-05};
+        BOOST_REQUIRE_EQUAL(sol.size(), expected.size());
+        for (size_t i = 0; i < sol.size(); ++i) {
+            for (int row = 0; row < bz; ++row) {
+                BOOST_CHECK_CLOSE(sol[i][row], expected[i][row], 1e-3);
+            }
+        }
+    }
+
+    // Test with 3x3 block solvers.
+    {
+        const int bz = 3;
+        auto sol = testSolver<bz>(prm, "matr33.txt", "rhs3.txt");
+        Dune::BlockVector<Dune::FieldVector<double, bz>> expected {{-1.62493, -1.76435e-06, 1.86991e-10},
+                                                                   {-458.542, 2.28308e-06, -2.45341e-07},
+                                                                   {-1.48005, -5.02264e-07, -1.049e-05}};
+        BOOST_REQUIRE_EQUAL(sol.size(), expected.size());
+        for (size_t i = 0; i < sol.size(); ++i) {
+            for (int row = 0; row < bz; ++row) {
+                BOOST_CHECK_CLOSE(sol[i][row], expected[i][row], 1e-3);
+            }
+        }
+    }
+}