amgclSolverBackend.hpp

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/*
  Copyright 2020 Equinor ASA
 
  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_AMGCLSOLVER_BACKEND_HEADER_INCLUDED
#define OPM_AMGCLSOLVER_BACKEND_HEADER_INCLUDED
 
#include <opm/simulators/linalg/bda/BdaResult.hpp>
#include <opm/simulators/linalg/bda/BdaSolver.hpp>
#include <opm/simulators/linalg/bda/WellContributions.hpp>
 
#include <boost/property_tree/ptree.hpp>
 
#include <amgcl/amg.hpp>
#include <amgcl/backend/builtin.hpp>
#include <amgcl/adapter/crs_tuple.hpp>
#include <amgcl/make_block_solver.hpp>
#include <amgcl/relaxation/as_preconditioner.hpp>
#include <amgcl/relaxation/ilu0.hpp>
#include <amgcl/solver/bicgstab.hpp>
#include <amgcl/preconditioner/runtime.hpp>
#include <amgcl/value_type/static_matrix.hpp>
 
#include <memory>
#include <mutex>
#include <vector>
 
namespace Opm
{
namespace Accelerator
{
 
template <unsigned int block_size>
class amgclSolverBackend : public BdaSolver<block_size>
{
    typedef BdaSolver<block_size> Base;
 
    using Base::N;
    using Base::Nb;
    using Base::nnz;
    using Base::nnzb;
    using Base::verbosity;
    using Base::platformID;
    using Base::deviceID;
    using Base::maxit;
    using Base::tolerance;
    using Base::initialized;
 
    typedef amgcl::static_matrix<double, block_size, block_size> dmat_type; // matrix value type in double precision
    typedef amgcl::static_matrix<double, block_size, 1> dvec_type; // the corresponding vector value type
    typedef amgcl::backend::builtin<dmat_type> CPU_Backend;
 
    typedef amgcl::make_solver<amgcl::runtime::preconditioner<CPU_Backend>, amgcl::runtime::solver::wrapper<CPU_Backend> > CPU_Solver;
 
private:
 
    // amgcl can use different backends, this lets the user choose
    enum Amgcl_backend_type {
        cpu,
        cuda,
        vexcl
    };
 
    // store matrix in CSR format
    std::vector<unsigned> A_rows, A_cols;
    std::vector<double> A_vals, rhs;
    std::vector<double> x;
    std::once_flag print_info;
    Amgcl_backend_type backend_type = cpu;
 
    boost::property_tree::ptree prm;         // amgcl parameters
    int iters = 0;
    double error = 0.0;
 
#if HAVE_CUDA
    std::once_flag cuda_initialize;
    void solve_cuda(double *b);
#endif
 
#if HAVE_VEXCL
    std::once_flag vexcl_initialize;
#endif
    void initialize(int Nb, int nnzbs);
 
    void convert_sparsity_pattern(int *rows, int *cols);
 
    void convert_data(double *vals, int *rows);
 
    void solve_system(double *b, BdaResult &res);
 
public:
    amgclSolverBackend(int linear_solver_verbosity, int maxit, double tolerance, unsigned int platformID, unsigned int deviceID);
 
    ~amgclSolverBackend();
 
    SolverStatus solve_system(std::shared_ptr<BlockedMatrix> matrix, double *b,
        std::shared_ptr<BlockedMatrix> jacMatrix, WellContributions& wellContribs, BdaResult &res) override;
    
    void get_result(double *x) override;
 
}; // end class amgclSolverBackend
 
} // namespace Accelerator
} // namespace Opm
 
#endif