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muSpectre/src/fft/fftwmpi_engine.cc
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fftwmpi_engine.cc
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/**
* @file fftw_engine_mpi.cc
*
* @author Lars Pastewka <lars.pastewka@imtek.uni-freiburg.de>
*
* @date 06 Mar 2017
*
* @brief implements the MPI-parallel fftw engine
*
* Copyright © 2017 Till Junge
*
* µSpectre 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, or (at
* your option) any later version.
*
* µSpectre 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 GNU Emacs; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "common/ccoord_operations.hh"
#include "fft/fftwmpi_engine.hh"
namespace muSpectre {
template <Dim_t DimsS, Dim_t DimM>
int FFTWMPIEngine<DimsS, DimM>::nb_engines{0};
template <Dim_t DimS, Dim_t DimM>
FFTWMPIEngine<DimS, DimM>::FFTWMPIEngine(Ccoord resolutions, Rcoord lengths,
MPI_Comm comm)
:Parent{resolutions, lengths}, comm{comm},
hermitian_resolutions{CcoordOps::get_hermitian_sizes(resolutions)}
{
if (!this->nb_engines) fftw_mpi_init();
this->nb_engines++;
for (auto && pixel: CcoordOps::Pixels<DimS>(this->hermitian_resolutions)) {
this->work_space_container.add_pixel(pixel);
}
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
void FFTWMPIEngine<DimS, DimM>::initialise(FFT_PlanFlags plan_flags) {
if (this->initialised) {
throw std::runtime_error("double initialisation, will leak memory");
}
Parent::initialise(plan_flags);
const int & rank = DimS;
int howmany = Field_t::nb_components;
std::array<ptrdiff_t, 3> narr;
std::copy(this->domain_resolutions.begin(), this->domain_resolutions.end(),
narr.begin());
narr[2] = this->domain_resolutions[2]/2+1;
ptrdiff_t loc_res_x, loc_loc_x;
ptrdiff_t loc_alloc_size{
fftw_mpi_local_size_many(
rank, narr.data(), howmany, FFTW_MPI_DEFAULT_BLOCK, this->comm,
&loc_res_x, &loc_loc_x)};
this->resolutions[0] = loc_res_x;
this->locations[0] = loc_loc_x;
//std::array<int, DimS> narr;
//const int * const n = &narr[0];
//std::copy(this->resolutions.begin(), this->resolutions.end(), narr.begin());
//temporary buffer for plan
Real * r_work_space = fftw_alloc_real(2*loc_alloc_size);
Real * in = r_work_space;
fftw_complex * out = reinterpret_cast<fftw_complex*>(this->work.data());
unsigned int flags;
switch (plan_flags) {
case FFT_PlanFlags::estimate: {
flags = FFTW_ESTIMATE;
break;
}
case FFT_PlanFlags::measure: {
flags = FFTW_MEASURE;
break;
}
case FFT_PlanFlags::patient: {
flags = FFTW_PATIENT;
break;
}
default:
throw std::runtime_error("unknown planner flag type");
break;
}
narr[2] = this->domain_resolutions[2];
this->plan_fft = fftw_mpi_plan_many_dft_r2c(
rank, narr.data(), howmany, FFTW_MPI_DEFAULT_BLOCK,
FFTW_MPI_DEFAULT_BLOCK, in, out, this->comm,
FFTW_PRESERVE_INPUT | flags);
if (this->plan_fft == nullptr) {
throw std::runtime_error("r2c plan failed");
}
fftw_mpi_execute_dft_r2c(
this->plan_fft, in, reinterpret_cast<fftw_complex*>(this->work.data()));
fftw_complex * i_in = reinterpret_cast<fftw_complex*>(this->work.data());
Real * i_out = r_work_space;
this->plan_ifft = fftw_mpi_plan_many_dft_c2r(
rank, narr.data(), howmany, FFTW_MPI_DEFAULT_BLOCK,
FFTW_MPI_DEFAULT_BLOCK, i_in, i_out, this->comm,
FFTW_PRESERVE_INPUT | flags);
if (this->plan_ifft == nullptr) {
throw std::runtime_error("c2r plan failed");
}
fftw_free(r_work_space);
this->initialised = true;
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
FFTWMPIEngine<DimS, DimM>::~FFTWMPIEngine<DimS, DimM>() noexcept {
fftw_destroy_plan(this->plan_fft);
fftw_destroy_plan(this->plan_ifft);
this->nb_engines--;
if (!this->nb_engines) fftw_mpi_cleanup();
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
typename FFTWMPIEngine<DimS, DimM>::Workspace_t &
FFTWMPIEngine<DimS, DimM>::fft (Field_t & field) {
fftw_mpi_execute_dft_r2c(
this->plan_fft, field.data(),
reinterpret_cast<fftw_complex*>(this->work.data()));
return this->work;
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
void
FFTWMPIEngine<DimS, DimM>::ifft (Field_t & field) const {
if (field.size() != CcoordOps::get_size(this->resolutions)) {
throw std::runtime_error("size mismatch");
}
fftw_mpi_execute_dft_c2r(
this->plan_ifft, reinterpret_cast<fftw_complex*>(this->work.data()),
field.data());
}
template class FFTWMPIEngine<twoD, twoD>;
template class FFTWMPIEngine<twoD, threeD>;
template class FFTWMPIEngine<threeD, threeD>;
} // muSpectre
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