src/gromacs/mdlib/update_constrain_gpu_impl.h

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  35 /*! \internal \file
  36  *
  37  * \brief Declares GPU implementation class for update and constraints.
  38  *
  39  * This header file is needed to include from both the device-side
  40  * kernels file, and the host-side management code.
  41  *
  42  * \author Artem Zhmurov <zhmurov@gmail.com>
  43  *
  44  * \ingroup module_mdlib
  45  */
  46 #ifndef GMX_MDLIB_UPDATE_CONSTRAIN_GPU_IMPL_H
  47 #define GMX_MDLIB_UPDATE_CONSTRAIN_GPU_IMPL_H
  48
  49 #include "gmxpre.h"
  50
  51 #include "gromacs/gpu_utils/gpueventsynchronizer.cuh"
  52 #include "gromacs/mdlib/leapfrog_gpu.cuh"
  53 #include "gromacs/mdlib/lincs_gpu.cuh"
  54 #include "gromacs/mdlib/settle_gpu.cuh"
  55 #include "gromacs/mdlib/update_constrain_gpu.h"
  56 #include "gromacs/mdtypes/inputrec.h"
  57
  58 namespace gmx
  59 {
  60
  61 /*! \internal \brief Class with interfaces and data for GPU version of Update-Constraint. */
  62 class UpdateConstrainGpu::Impl
  63 {
  64
  65 public:
  66     /*! \brief Create Update-Constrain object.
  67      *
  68      * The constructor is given a non-nullptr \p commandStream, in which all the update and constrain
  69      * routines are executed. \p xUpdatedOnDevice should mark the completion of all kernels that modify
  70      * coordinates. The event is maintained outside this class and also passed to all (if any) consumers
  71      * of the updated coordinates. The \p xUpdatedOnDevice also can not be a nullptr because the
  72      * markEvent(...) method is called unconditionally.
  73      *
  74      * \param[in] ir                Input record data: LINCS takes number of iterations and order of
  75      *                              projection from it.
  76      * \param[in] mtop              Topology of the system: SETTLE gets the masses for O and H atoms
  77      *                              and target O-H and H-H distances from this object.
  78      * \param[in] deviceContext     GPU device context.
  79      * \param[in] commandStream     GPU stream to use. Can be nullptr.
  80      * \param[in] xUpdatedOnDevice  The event synchronizer to use to mark that update is done on the GPU.
  81      */
  82     Impl(const t_inputrec&     ir,
  83          const gmx_mtop_t&     mtop,
  84          const DeviceContext&  deviceContext,
  85          const void*           commandStream,
  86          GpuEventSynchronizer* xUpdatedOnDevice);
  87
  88     ~Impl();
  89
  90     /*! \brief Integrate
  91      *
  92      * Integrates the equation of motion using Leap-Frog algorithm and applies
  93      * LINCS and SETTLE constraints.
  94      * If computeVirial is true, constraints virial is written at the provided pointer.
  95      * doTempCouple should be true if:
  96      *   1. The temperature coupling is enabled.
  97      *   2. This is the temperature coupling step.
  98      * Parameters virial/lambdas can be nullptr if computeVirial/doTempCouple are false.
  99      *
 100      * \param[in]  fReadyOnDevice           Event synchronizer indicating that the forces are ready in
 101      *                                      the device memory.
 102      * \param[in]  dt                       Timestep.
 103      * \param[in]  updateVelocities         If the velocities should be constrained.
 104      * \param[in]  computeVirial            If virial should be updated.
 105      * \param[out] virial                   Place to save virial tensor.
 106      * \param[in]  doTemperatureScaling     If velocities should be scaled for temperature coupling.
 107      * \param[in]  tcstat                   Temperature coupling data.
 108      * \param[in]  doParrinelloRahman       If current step is a Parrinello-Rahman pressure coupling step.
 109      * \param[in]  dtPressureCouple         Period between pressure coupling steps.
 110      * \param[in]  prVelocityScalingMatrix  Parrinello-Rahman velocity scaling matrix.
 111      */
 112     void integrate(GpuEventSynchronizer*             fReadyOnDevice,
 113                    real                              dt,
 114                    bool                              updateVelocities,
 115                    bool                              computeVirial,
 116                    tensor                            virial,
 117                    bool                              doTemperatureScaling,
 118                    gmx::ArrayRef<const t_grp_tcstat> tcstat,
 119                    bool                              doParrinelloRahman,
 120                    float                             dtPressureCouple,
 121                    const matrix                      prVelocityScalingMatrix);
 122
 123     /*! \brief Scale coordinates on the GPU for the pressure coupling.
 124      *
 125      * After pressure coupling step, the box size may change. Hence, the coordinates should be
 126      * scaled so that all the particles fit in the new box.
 127      *
 128      * \param[in] scalingMatrix Coordinates scaling matrix.
 129      */
 130     void scaleCoordinates(const matrix scalingMatrix);
 131
 132     /*! \brief Set the pointers and update data-structures (e.g. after NB search step).
 133      *
 134      * \param[in,out]  d_x            Device buffer with coordinates.
 135      * \param[in,out]  d_v            Device buffer with velocities.
 136      * \param[in]      d_f            Device buffer with forces.
 137      * \param[in] idef                System topology
 138      * \param[in] md                  Atoms data.
 139      * \param[in] numTempScaleValues  Number of temperature scaling groups. Set zero for no temperature coupling.
 140      */
 141     void set(DeviceBuffer<RVec>            d_x,
 142              DeviceBuffer<RVec>            d_v,
 143              const DeviceBuffer<RVec>      d_f,
 144              const InteractionDefinitions& idef,
 145              const t_mdatoms&              md,
 146              const int                     numTempScaleValues);
 147
 148     /*! \brief
 149      * Update PBC data.
 150      *
 151      * Converts PBC data from t_pbc into the PbcAiuc format and stores the latter.
 152      *
 153      * \param[in] pbcType The type of the periodic boundary.
 154      * \param[in] box     The periodic boundary box matrix.
 155      */
 156     void setPbc(PbcType pbcType, const matrix box);
 157
 158     /*! \brief Return the synchronizer associated with the event indicated that the coordinates are ready on the device.
 159      */
 160     GpuEventSynchronizer* getCoordinatesReadySync();
 161
 162     /*! \brief
 163      * Returns whether the maximum number of coupled constraints is supported
 164      * by the GPU LINCS code.
 165      *
 166      * \param[in] mtop The molecular topology
 167      */
 168     static bool isNumCoupledConstraintsSupported(const gmx_mtop_t& mtop);
 169
 170 private:
 171     //! GPU context object
 172     const DeviceContext& deviceContext_;
 173     //! GPU stream
 174     CommandStream commandStream_ = nullptr;
 175     //! GPU kernel launch config
 176     KernelLaunchConfig coordinateScalingKernelLaunchConfig_;
 177
 178     //! Periodic boundary data
 179     PbcAiuc pbcAiuc_;
 180
 181     //! Number of atoms
 182     int numAtoms_;
 183
 184     //! Local copy of the pointer to the device positions buffer
 185     float3* d_x_;
 186     //! Local copy of the pointer to the device velocities buffer
 187     float3* d_v_;
 188     //! Local copy of the pointer to the device forces buffer
 189     float3* d_f_;
 190
 191     //! Device buffer for intermediate positions (maintained internally)
 192     float3* d_xp_;
 193     //! Number of elements in shifted coordinates buffer
 194     int numXp_ = -1;
 195     //! Allocation size for the shifted coordinates buffer
 196     int numXpAlloc_ = -1;
 197
 198
 199     //! 1/mass for all atoms (GPU)
 200     real* d_inverseMasses_;
 201     //! Number of elements in reciprocal masses buffer
 202     int numInverseMasses_ = -1;
 203     //! Allocation size for the reciprocal masses buffer
 204     int numInverseMassesAlloc_ = -1;
 205
 206     //! Leap-Frog integrator
 207     std::unique_ptr<LeapFrogGpu> integrator_;
 208     //! LINCS GPU object to use for non-water constraints
 209     std::unique_ptr<LincsGpu> lincsGpu_;
 210     //! SETTLE GPU object for water constrains
 211     std::unique_ptr<SettleGpu> settleGpu_;
 212
 213     //! An pointer to the event to indicate when the update of coordinates is complete
 214     GpuEventSynchronizer* coordinatesReady_;
 215 };
 216
 217 } // namespace gmx
 218
 219 #endif // GMX_MDLIB_UPDATE_CONSTRAIN_GPU_IMPL_H