src/gromacs/mdlib/update_constrain_gpu_impl.cpp

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  35 /*! \internal \file
  36  *
  37  * \brief Implements update and constraints class.
  38  *
  39  * The class combines Leap-Frog integrator with LINCS and SETTLE constraints.
  40  *
  41  * \todo The computational procedures in members should be integrated to improve
  42  *       computational performance.
  43  *
  44  * \author Artem Zhmurov <zhmurov@gmail.com>
  45  *
  46  * \ingroup module_mdlib
  47  */
  48 #include "gmxpre.h"
  49
  50 #include "update_constrain_gpu_impl.h"
  51
  52 #include <assert.h>
  53 #include <stdio.h>
  54
  55 #include <cmath>
  56
  57 #include <algorithm>
  58
  59 #include "gromacs/gpu_utils/device_context.h"
  60 #include "gromacs/gpu_utils/device_stream.h"
  61 #include "gromacs/gpu_utils/devicebuffer.h"
  62 #include "gromacs/gpu_utils/gpueventsynchronizer.h"
  63 #include "gromacs/gpu_utils/gputraits.h"
  64 #include "gromacs/mdlib/leapfrog_gpu.h"
  65 #include "gromacs/mdlib/update_constrain_gpu.h"
  66 #include "gromacs/mdlib/update_constrain_gpu_internal.h"
  67 #include "gromacs/mdtypes/mdatom.h"
  68 #include "gromacs/timing/wallcycle.h"
  69 #include "gromacs/topology/mtop_util.h"
  70
  71 static constexpr bool sc_haveGpuConstraintSupport = GMX_GPU_CUDA;
  72
  73 namespace gmx
  74 {
  75
  76 void UpdateConstrainGpu::Impl::integrate(GpuEventSynchronizer*             fReadyOnDevice,
  77                                          const real                        dt,
  78                                          const bool                        updateVelocities,
  79                                          const bool                        computeVirial,
  80                                          tensor                            virial,
  81                                          const bool                        doTemperatureScaling,
  82                                          gmx::ArrayRef<const t_grp_tcstat> tcstat,
  83                                          const bool                        doParrinelloRahman,
  84                                          const float                       dtPressureCouple,
  85                                          const matrix                      prVelocityScalingMatrix)
  86 {
  87     wallcycle_start_nocount(wcycle_, WallCycleCounter::LaunchGpu);
  88     wallcycle_sub_start(wcycle_, WallCycleSubCounter::LaunchGpuUpdateConstrain);
  89
  90     // Clearing virial matrix
  91     // TODO There is no point in having separate virial matrix for constraints
  92     clear_mat(virial);
  93
  94     // Make sure that the forces are ready on device before proceeding with the update.
  95     fReadyOnDevice->enqueueWaitEvent(deviceStream_);
  96
  97     // The integrate should save a copy of the current coordinates in d_xp_ and write updated
  98     // once into d_x_. The d_xp_ is only needed by constraints.
  99     integrator_->integrate(
 100             d_x_, d_xp_, d_v_, d_f_, dt, doTemperatureScaling, tcstat, doParrinelloRahman, dtPressureCouple, prVelocityScalingMatrix);
 101     // Constraints need both coordinates before (d_x_) and after (d_xp_) update. However, after constraints
 102     // are applied, the d_x_ can be discarded. So we intentionally swap the d_x_ and d_xp_ here to avoid the
 103     // d_xp_ -> d_x_ copy after constraints. Note that the integrate saves them in the wrong order as well.
 104     if (sc_haveGpuConstraintSupport)
 105     {
 106         lincsGpu_->apply(d_xp_, d_x_, updateVelocities, d_v_, 1.0 / dt, computeVirial, virial, pbcAiuc_);
 107         settleGpu_->apply(d_xp_, d_x_, updateVelocities, d_v_, 1.0 / dt, computeVirial, virial, pbcAiuc_);
 108     }
 109
 110     // scaledVirial -> virial (methods above returns scaled values)
 111     float scaleFactor = 0.5F / (dt * dt);
 112     for (int i = 0; i < DIM; i++)
 113     {
 114         for (int j = 0; j < DIM; j++)
 115         {
 116             virial[i][j] = scaleFactor * virial[i][j];
 117         }
 118     }
 119
 120     coordinatesReady_->markEvent(deviceStream_);
 121
 122     wallcycle_sub_stop(wcycle_, WallCycleSubCounter::LaunchGpuUpdateConstrain);
 123     wallcycle_stop(wcycle_, WallCycleCounter::LaunchGpu);
 124 }
 125
 126 void UpdateConstrainGpu::Impl::scaleCoordinates(const matrix scalingMatrix)
 127 {
 128     wallcycle_start_nocount(wcycle_, WallCycleCounter::LaunchGpu);
 129     wallcycle_sub_start(wcycle_, WallCycleSubCounter::LaunchGpuUpdateConstrain);
 130
 131     ScalingMatrix mu(scalingMatrix);
 132
 133     launchScaleCoordinatesKernel(numAtoms_, d_x_, mu, deviceStream_);
 134
 135     wallcycle_sub_stop(wcycle_, WallCycleSubCounter::LaunchGpuUpdateConstrain);
 136     wallcycle_stop(wcycle_, WallCycleCounter::LaunchGpu);
 137 }
 138
 139 void UpdateConstrainGpu::Impl::scaleVelocities(const matrix scalingMatrix)
 140 {
 141     wallcycle_start_nocount(wcycle_, WallCycleCounter::LaunchGpu);
 142     wallcycle_sub_start(wcycle_, WallCycleSubCounter::LaunchGpuUpdateConstrain);
 143
 144     ScalingMatrix mu(scalingMatrix);
 145
 146     launchScaleCoordinatesKernel(numAtoms_, d_v_, mu, deviceStream_);
 147
 148     wallcycle_sub_stop(wcycle_, WallCycleSubCounter::LaunchGpuUpdateConstrain);
 149     wallcycle_stop(wcycle_, WallCycleCounter::LaunchGpu);
 150 }
 151
 152 UpdateConstrainGpu::Impl::Impl(const t_inputrec&     ir,
 153                                const gmx_mtop_t&     mtop,
 154                                const int             numTempScaleValues,
 155                                const DeviceContext&  deviceContext,
 156                                const DeviceStream&   deviceStream,
 157                                GpuEventSynchronizer* xUpdatedOnDevice,
 158                                gmx_wallcycle*        wcycle) :
 159     deviceContext_(deviceContext),
 160     deviceStream_(deviceStream),
 161     coordinatesReady_(xUpdatedOnDevice),
 162     wcycle_(wcycle)
 163 {
 164     GMX_ASSERT(xUpdatedOnDevice != nullptr, "The event synchronizer can not be nullptr.");
 165
 166     integrator_ = std::make_unique<LeapFrogGpu>(deviceContext_, deviceStream_, numTempScaleValues);
 167     if (sc_haveGpuConstraintSupport)
 168     {
 169         lincsGpu_ = std::make_unique<LincsGpu>(ir.nLincsIter, ir.nProjOrder, deviceContext_, deviceStream_);
 170         settleGpu_ = std::make_unique<SettleGpu>(mtop, deviceContext_, deviceStream_);
 171     }
 172 }
 173
 174 UpdateConstrainGpu::Impl::~Impl() {}
 175
 176 void UpdateConstrainGpu::Impl::set(DeviceBuffer<Float3>          d_x,
 177                                    DeviceBuffer<Float3>          d_v,
 178                                    const DeviceBuffer<Float3>    d_f,
 179                                    const InteractionDefinitions& idef,
 180                                    const t_mdatoms&              md)
 181 {
 182     wallcycle_start_nocount(wcycle_, WallCycleCounter::LaunchGpu);
 183     wallcycle_sub_start(wcycle_, WallCycleSubCounter::LaunchGpuUpdateConstrain);
 184
 185     GMX_ASSERT(d_x, "Coordinates device buffer should not be null.");
 186     GMX_ASSERT(d_v, "Velocities device buffer should not be null.");
 187     GMX_ASSERT(d_f, "Forces device buffer should not be null.");
 188
 189     d_x_ = d_x;
 190     d_v_ = d_v;
 191     d_f_ = d_f;
 192
 193     numAtoms_ = md.nr;
 194
 195     reallocateDeviceBuffer(&d_xp_, numAtoms_, &numXp_, &numXpAlloc_, deviceContext_);
 196
 197     reallocateDeviceBuffer(
 198             &d_inverseMasses_, numAtoms_, &numInverseMasses_, &numInverseMassesAlloc_, deviceContext_);
 199
 200     // Integrator should also update something, but it does not even have a method yet
 201     integrator_->set(numAtoms_, md.invmass, md.cTC);
 202     if (sc_haveGpuConstraintSupport)
 203     {
 204         lincsGpu_->set(idef, numAtoms_, md.invmass);
 205         settleGpu_->set(idef);
 206     }
 207     else
 208     {
 209         GMX_ASSERT(idef.il[F_SETTLE].empty(), "SETTLE not supported");
 210         GMX_ASSERT(idef.il[F_CONSTR].empty(), "LINCS not supported");
 211     }
 212
 213     wallcycle_sub_stop(wcycle_, WallCycleSubCounter::LaunchGpuUpdateConstrain);
 214     wallcycle_stop(wcycle_, WallCycleCounter::LaunchGpu);
 215 }
 216
 217 void UpdateConstrainGpu::Impl::setPbc(const PbcType pbcType, const matrix box)
 218 {
 219     // TODO wallcycle
 220     setPbcAiuc(numPbcDimensions(pbcType), box, &pbcAiuc_);
 221 }
 222
 223 GpuEventSynchronizer* UpdateConstrainGpu::Impl::getCoordinatesReadySync()
 224 {
 225     return coordinatesReady_;
 226 }
 227
 228 UpdateConstrainGpu::UpdateConstrainGpu(const t_inputrec&     ir,
 229                                        const gmx_mtop_t&     mtop,
 230                                        const int             numTempScaleValues,
 231                                        const DeviceContext&  deviceContext,
 232                                        const DeviceStream&   deviceStream,
 233                                        GpuEventSynchronizer* xUpdatedOnDevice,
 234                                        gmx_wallcycle*        wcycle) :
 235     impl_(new Impl(ir, mtop, numTempScaleValues, deviceContext, deviceStream, xUpdatedOnDevice, wcycle))
 236 {
 237 }
 238
 239 UpdateConstrainGpu::~UpdateConstrainGpu() = default;
 240
 241 void UpdateConstrainGpu::integrate(GpuEventSynchronizer*             fReadyOnDevice,
 242                                    const real                        dt,
 243                                    const bool                        updateVelocities,
 244                                    const bool                        computeVirial,
 245                                    tensor                            virialScaled,
 246                                    const bool                        doTemperatureScaling,
 247                                    gmx::ArrayRef<const t_grp_tcstat> tcstat,
 248                                    const bool                        doParrinelloRahman,
 249                                    const float                       dtPressureCouple,
 250                                    const matrix                      prVelocityScalingMatrix)
 251 {
 252     impl_->integrate(fReadyOnDevice,
 253                      dt,
 254                      updateVelocities,
 255                      computeVirial,
 256                      virialScaled,
 257                      doTemperatureScaling,
 258                      tcstat,
 259                      doParrinelloRahman,
 260                      dtPressureCouple,
 261                      prVelocityScalingMatrix);
 262 }
 263
 264 void UpdateConstrainGpu::scaleCoordinates(const matrix scalingMatrix)
 265 {
 266     impl_->scaleCoordinates(scalingMatrix);
 267 }
 268
 269 void UpdateConstrainGpu::scaleVelocities(const matrix scalingMatrix)
 270 {
 271     impl_->scaleVelocities(scalingMatrix);
 272 }
 273
 274 void UpdateConstrainGpu::set(DeviceBuffer<Float3>          d_x,
 275                              DeviceBuffer<Float3>          d_v,
 276                              const DeviceBuffer<Float3>    d_f,
 277                              const InteractionDefinitions& idef,
 278                              const t_mdatoms&              md)
 279 {
 280     impl_->set(d_x, d_v, d_f, idef, md);
 281 }
 282
 283 void UpdateConstrainGpu::setPbc(const PbcType pbcType, const matrix box)
 284 {
 285     impl_->setPbc(pbcType, box);
 286 }
 287
 288 GpuEventSynchronizer* UpdateConstrainGpu::getCoordinatesReadySync()
 289 {
 290     return impl_->getCoordinatesReadySync();
 291 }
 292
 293 bool UpdateConstrainGpu::isNumCoupledConstraintsSupported(const gmx_mtop_t& mtop)
 294 {
 295     return LincsGpu::isNumCoupledConstraintsSupported(mtop);
 296 }
 297
 298 bool UpdateConstrainGpu::areConstraintsSupported()
 299 {
 300     return sc_haveGpuConstraintSupport;
 301 }
 302
 303 } // namespace gmx