[de061d] | 1 | /*
|
---|
| 2 | * vmg - a versatile multigrid solver
|
---|
| 3 | * Copyright (C) 2012 Institute for Numerical Simulation, University of Bonn
|
---|
| 4 | *
|
---|
| 5 | * vmg is free software: you can redistribute it and/or modify
|
---|
| 6 | * it under the terms of the GNU General Public License as published by
|
---|
| 7 | * the Free Software Foundation, either version 3 of the License, or
|
---|
| 8 | * (at your option) any later version.
|
---|
| 9 | *
|
---|
| 10 | * vmg is distributed in the hope that it will be useful,
|
---|
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
|
---|
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
---|
| 13 | * GNU General Public License for more details.
|
---|
| 14 | *
|
---|
| 15 | * You should have received a copy of the GNU General Public License
|
---|
| 16 | * along with this program. If not, see <http://www.gnu.org/licenses/>.
|
---|
| 17 | */
|
---|
| 18 |
|
---|
| 19 | /**
|
---|
| 20 | * @file gsrb_poisson_2.cpp
|
---|
| 21 | * @author Julian Iseringhausen <isering@ins.uni-bonn.de>
|
---|
| 22 | * @date Fri May 11 18:30:20 2012
|
---|
| 23 | *
|
---|
| 24 | * @brief Gauss-Seidel Red Black method, specialized to
|
---|
| 25 | * the Poisson equation. Performance improved by
|
---|
| 26 | * explicit loop unrolling.
|
---|
| 27 | *
|
---|
| 28 | */
|
---|
| 29 |
|
---|
| 30 | #ifdef HAVE_CONFIG_H
|
---|
| 31 | #include <libvmg_config.h>
|
---|
| 32 | #endif
|
---|
| 33 |
|
---|
| 34 | #ifdef HAVE_MPI
|
---|
| 35 | #include <mpi.h>
|
---|
| 36 | #endif
|
---|
| 37 |
|
---|
| 38 | #include "base/helper.hpp"
|
---|
| 39 | #include "comm/comm.hpp"
|
---|
| 40 | #include "grid/grid.hpp"
|
---|
| 41 | #include "smoother/gsrb_poisson_2.hpp"
|
---|
| 42 | #include "mg.hpp"
|
---|
| 43 |
|
---|
| 44 | using namespace VMG;
|
---|
| 45 |
|
---|
| 46 | static inline void ComputePartial(Grid& sol, Grid& rhs,
|
---|
| 47 | const Index& begin, const Index& end,
|
---|
| 48 | const vmg_float& prefactor, const int& off)
|
---|
| 49 | {
|
---|
| 50 | const vmg_float fac = 1.0 / 6.0;
|
---|
| 51 |
|
---|
| 52 | for (int i=begin.X(); i<end.X(); ++i)
|
---|
| 53 | for (int j=begin.Y(); j<end.Y(); ++j)
|
---|
| 54 | for (int k=begin.Z() + (i + j + begin.Z() + off) % 2; k<end.Z(); k+=2)
|
---|
| 55 | sol(i,j,k) = prefactor * rhs.GetVal(i,j,k) + fac * (sol.GetVal(i-1,j ,k ) +
|
---|
| 56 | sol.GetVal(i+1,j ,k ) +
|
---|
| 57 | sol.GetVal(i ,j-1,k ) +
|
---|
| 58 | sol.GetVal(i ,j+1,k ) +
|
---|
| 59 | sol.GetVal(i ,j ,k-1) +
|
---|
| 60 | sol.GetVal(i ,j ,k+1));
|
---|
| 61 | }
|
---|
| 62 |
|
---|
| 63 | void GaussSeidelRBPoisson2::Compute(Grid& sol, Grid& rhs)
|
---|
| 64 | {
|
---|
| 65 | const vmg_float prefactor_inv = Helper::pow_2(sol.Extent().MeshWidth().Max()) / 6.0;
|
---|
| 66 | const int off = rhs.Global().LocalBegin().Sum() - rhs.Global().GlobalBegin().Sum() + rhs.Local().HaloSize1().Sum();
|
---|
| 67 | const LocalIndices& local = rhs.Local();
|
---|
| 68 | Comm& comm = *MG::GetComm();
|
---|
| 69 |
|
---|
| 70 | /*
|
---|
| 71 | * Compute first halfstep
|
---|
| 72 | */
|
---|
| 73 |
|
---|
| 74 | // Start asynchronous communication
|
---|
| 75 | comm.CommToGhostsAsyncStart(sol);
|
---|
| 76 |
|
---|
| 77 | // Smooth part not depending on ghost cells
|
---|
| 78 | ComputePartial(sol, rhs,
|
---|
| 79 | local.Begin()+1, local.End()-1,
|
---|
| 80 | prefactor_inv, off+1);
|
---|
| 81 |
|
---|
| 82 | // Finish asynchronous communication
|
---|
| 83 | comm.CommToGhostsAsyncFinish(sol);
|
---|
| 84 |
|
---|
| 85 | /*
|
---|
| 86 | * Smooth near boundary cells
|
---|
| 87 | */
|
---|
| 88 |
|
---|
| 89 | ComputePartial(sol, rhs,
|
---|
| 90 | local.Begin(),
|
---|
| 91 | Index(local.Begin().X()+1, local.End().Y(), local.End().Z()),
|
---|
| 92 | prefactor_inv, off+1);
|
---|
| 93 |
|
---|
| 94 | ComputePartial(sol, rhs,
|
---|
| 95 | Index(local.End().X()-1, local.Begin().Y(), local.Begin().Z()),
|
---|
| 96 | local.End(),
|
---|
| 97 | prefactor_inv, off+1);
|
---|
| 98 |
|
---|
| 99 | ComputePartial(sol, rhs,
|
---|
| 100 | Index(local.Begin().X()+1, local.Begin().Y(), local.Begin().Z()),
|
---|
| 101 | Index(local.End().X()-1, local.Begin().Y()+1, local.End().Z()),
|
---|
| 102 | prefactor_inv, off+1);
|
---|
| 103 |
|
---|
| 104 | ComputePartial(sol, rhs,
|
---|
| 105 | Index(local.Begin().X()+1, local.End().Y()-1, local.Begin().Z()),
|
---|
| 106 | Index(local.End().X()-1, local.End().Y(), local.End().Z()),
|
---|
| 107 | prefactor_inv, off+1);
|
---|
| 108 |
|
---|
| 109 | ComputePartial(sol, rhs,
|
---|
| 110 | Index(local.Begin().X()+1, local.Begin().Y()+1, local.Begin().Z()),
|
---|
| 111 | Index(local.End().X()-1, local.End().Y()-1, local.Begin().Z()+1),
|
---|
| 112 | prefactor_inv, off+1);
|
---|
| 113 |
|
---|
| 114 | ComputePartial(sol, rhs,
|
---|
| 115 | Index(local.Begin().X()+1, local.Begin().Y()+1, local.End().Z()-1),
|
---|
| 116 | Index(local.End().X()-1, local.End().Y()-1, local.End().Z()),
|
---|
| 117 | prefactor_inv, off+1);
|
---|
| 118 |
|
---|
| 119 | /*
|
---|
| 120 | * Compute second halfstep
|
---|
| 121 | */
|
---|
| 122 |
|
---|
| 123 | // Start asynchronous communication
|
---|
| 124 | comm.CommToGhostsAsyncStart(sol);
|
---|
| 125 |
|
---|
| 126 | // Smooth part not depending on ghost cells
|
---|
| 127 | ComputePartial(sol, rhs,
|
---|
| 128 | local.Begin()+1, local.End()-1,
|
---|
| 129 | prefactor_inv, off);
|
---|
| 130 |
|
---|
| 131 | // Finish asynchronous communication
|
---|
| 132 | comm.CommToGhostsAsyncFinish(sol);
|
---|
| 133 |
|
---|
| 134 | /*
|
---|
| 135 | * Smooth near boundary cells
|
---|
| 136 | */
|
---|
| 137 |
|
---|
| 138 | ComputePartial(sol, rhs,
|
---|
| 139 | local.Begin(),
|
---|
| 140 | Index(local.Begin().X()+1, local.End().Y(), local.End().Z()),
|
---|
| 141 | prefactor_inv, off);
|
---|
| 142 |
|
---|
| 143 | ComputePartial(sol, rhs,
|
---|
| 144 | Index(local.End().X()-1, local.Begin().Y(), local.Begin().Z()),
|
---|
| 145 | local.End(),
|
---|
| 146 | prefactor_inv, off);
|
---|
| 147 |
|
---|
| 148 | ComputePartial(sol, rhs,
|
---|
| 149 | Index(local.Begin().X()+1, local.Begin().Y(), local.Begin().Z()),
|
---|
| 150 | Index(local.End().X()-1, local.Begin().Y()+1, local.End().Z()),
|
---|
| 151 | prefactor_inv, off);
|
---|
| 152 |
|
---|
| 153 | ComputePartial(sol, rhs,
|
---|
| 154 | Index(local.Begin().X()+1, local.End().Y()-1, local.Begin().Z()),
|
---|
| 155 | Index(local.End().X()-1, local.End().Y(), local.End().Z()),
|
---|
| 156 | prefactor_inv, off);
|
---|
| 157 |
|
---|
| 158 | ComputePartial(sol, rhs,
|
---|
| 159 | Index(local.Begin().X()+1, local.Begin().Y()+1, local.Begin().Z()),
|
---|
| 160 | Index(local.End().X()-1, local.End().Y()-1, local.Begin().Z()+1),
|
---|
| 161 | prefactor_inv, off);
|
---|
| 162 |
|
---|
| 163 | ComputePartial(sol, rhs,
|
---|
| 164 | Index(local.Begin().X()+1, local.Begin().Y()+1, local.End().Z()-1),
|
---|
| 165 | Index(local.End().X()-1, local.End().Y()-1, local.End().Z()),
|
---|
| 166 | prefactor_inv, off);
|
---|
| 167 | }
|
---|