[alexxy/gromacs.git] / src / gromacs / ewald / pme.h

/*
 * This file is part of the GROMACS molecular simulation package.
 *
 * Copyright (c) 1991-2000, University of Groningen, The Netherlands.
 * Copyright (c) 2001-2004, The GROMACS development team.
 * Copyright (c) 2013,2014,2015,2016,2017,2018,2019, by the GROMACS development team, led by
 * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
 * and including many others, as listed in the AUTHORS file in the
 * top-level source directory and at http://www.gromacs.org.
 *
 * GROMACS is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * of the License, or (at your option) any later version.
 *
 * GROMACS 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with GROMACS; if not, see
 * http://www.gnu.org/licenses, or write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA.
 *
 * If you want to redistribute modifications to GROMACS, please
 * consider that scientific software is very special. Version
 * control is crucial - bugs must be traceable. We will be happy to
 * consider code for inclusion in the official distribution, but
 * derived work must not be called official GROMACS. Details are found
 * in the README & COPYING files - if they are missing, get the
 * official version at http://www.gromacs.org.
 *
 * To help us fund GROMACS development, we humbly ask that you cite
 * the research papers on the package. Check out http://www.gromacs.org.
 */
/*! \libinternal \file
 *
 * \brief This file contains function declarations necessary for
 * computing energies and forces for the PME long-ranged part (Coulomb
 * and LJ).
 *
 * \author Berk Hess <hess@kth.se>
 * \inlibraryapi
 * \ingroup module_ewald
 */

#ifndef GMX_EWALD_PME_H
#define GMX_EWALD_PME_H

#include <string>

#include "gromacs/gpu_utils/devicebuffer_datatype.h"
#include "gromacs/gpu_utils/gpu_macros.h"
#include "gromacs/math/vectypes.h"
#include "gromacs/timing/walltime_accounting.h"
#include "gromacs/utility/arrayref.h"
#include "gromacs/utility/basedefinitions.h"
#include "gromacs/utility/real.h"

struct gmx_hw_info_t;
struct interaction_const_t;
struct t_commrec;
struct t_inputrec;
struct t_nrnb;
struct PmeGpu;
struct gmx_wallclock_gpu_pme_t;
struct gmx_device_info_t;
struct gmx_enerdata_t;
struct gmx_mtop_t;
struct gmx_pme_t;
struct gmx_wallcycle;
struct NumPmeDomains;

enum class GpuTaskCompletion;
class PmeGpuProgram;
class GpuEventSynchronizer;
//! Convenience name.
using PmeGpuProgramHandle = const PmeGpuProgram *;

namespace gmx
{
class ForceWithVirial;
class MDLogger;
enum class PinningPolicy : int;
}

enum {
    GMX_SUM_GRID_FORWARD, GMX_SUM_GRID_BACKWARD
};

/*! \brief Possible PME codepaths on a rank.
 * \todo: make this enum class with gmx_pme_t C++ refactoring
 */
enum class PmeRunMode
{
    None,    //!< No PME task is done
    CPU,     //!< Whole PME computation is done on CPU
    GPU,     //!< Whole PME computation is done on GPU
    Mixed,   //!< Mixed mode: only spread and gather run on GPU; FFT and solving are done on CPU.
};

//! PME gathering output forces treatment
enum class PmeForceOutputHandling
{
    Set,             /**< Gather simply writes into provided force buffer */
    ReduceWithInput, /**< Gather adds its output to the buffer.
                        On GPU, that means additional H2D copy before the kernel launch. */
};

/*! \brief Return the smallest allowed PME grid size for \p pmeOrder */
int minimalPmeGridSize(int pmeOrder);

/*! \brief Check restrictions on pme_order and the PME grid nkx,nky,nkz.
 *
 * With errorsAreFatal=true, an exception or fatal error is generated
 * on violation of restrictions.
 * With errorsAreFatal=false, false is returned on violation of restrictions.
 * When all restrictions are obeyed, true is returned.
 * Argument useThreads tells if any MPI rank doing PME uses more than 1 threads.
 * If at calling useThreads is unknown, pass true for conservative checking.
 *
 * The PME GPU restrictions are checked separately during pme_gpu_init().
 */
bool gmx_pme_check_restrictions(int pme_order,
                                int nkx, int nky, int nkz,
                                int numPmeDomainsAlongX,
                                bool useThreads,
                                bool errorsAreFatal);

/*! \brief Construct PME data
 *
 * \throws   gmx::InconsistentInputError if input grid sizes/PME order are inconsistent.
 * \returns  Pointer to newly allocated and initialized PME data.
 *
 * \todo We should evolve something like a \c GpuManager that holds \c
 * gmx_device_info_t * and \c PmeGpuProgramHandle and perhaps other
 * related things whose lifetime can/should exceed that of a task (or
 * perhaps task manager). See Redmine #2522.
 */
gmx_pme_t *gmx_pme_init(const t_commrec *cr,
                        const NumPmeDomains &numPmeDomains,
                        const t_inputrec *ir,
                        gmx_bool bFreeEnergy_q, gmx_bool bFreeEnergy_lj,
                        gmx_bool bReproducible,
                        real ewaldcoeff_q, real ewaldcoeff_lj,
                        int nthread,
                        PmeRunMode runMode,
                        PmeGpu *pmeGpu,
                        const gmx_device_info_t *gpuInfo,
                        PmeGpuProgramHandle pmeGpuProgram,
                        const gmx::MDLogger &mdlog);

/*! \brief Destroys the PME data structure.*/
void gmx_pme_destroy(gmx_pme_t *pme);

//@{
/*! \brief Flag values that control what gmx_pme_do() will calculate
 *
 * These can be combined with bitwise-OR if more than one thing is required.
 */
#define GMX_PME_SPREAD        (1<<0)
#define GMX_PME_SOLVE         (1<<1)
#define GMX_PME_CALC_F        (1<<2)
#define GMX_PME_CALC_ENER_VIR (1<<3)
/* This forces the grid to be backtransformed even without GMX_PME_CALC_F */
#define GMX_PME_CALC_POT      (1<<4)

#define GMX_PME_DO_ALL_F  (GMX_PME_SPREAD | GMX_PME_SOLVE | GMX_PME_CALC_F)
//@}

/*! \brief Do a PME calculation on a CPU for the long range electrostatics and/or LJ.
 *
 * Computes the PME forces and the energy and viral, when requested,
 * for all atoms in \p coordinates. Forces, when requested, are added
 * to the buffer \p forces, which is allowed to contain more elements
 * than the number of elements in \p coordinates.
 * The meaning of \p flags is defined above, and determines which
 * parts of the calculation are performed.
 *
 * \return 0 indicates all well, non zero is an error code.
 */
int gmx_pme_do(struct gmx_pme_t *pme,
               gmx::ArrayRef<const gmx::RVec> coordinates,
               gmx::ArrayRef<gmx::RVec>       forces,
               real chargeA[],  real chargeB[],
               real c6A[],      real c6B[],
               real sigmaA[],   real sigmaB[],
               const matrix box, const t_commrec *cr,
               int  maxshift_x, int maxshift_y,
               t_nrnb *nrnb,    gmx_wallcycle *wcycle,
               matrix vir_q,    matrix vir_lj,
               real *energy_q,  real *energy_lj,
               real lambda_q,   real lambda_lj,
               real *dvdlambda_q, real *dvdlambda_lj,
               int flags);

/*! \brief Called on the nodes that do PME exclusively */
int gmx_pmeonly(struct gmx_pme_t *pme,
                const t_commrec *cr,     t_nrnb *mynrnb,
                gmx_wallcycle  *wcycle,
                gmx_walltime_accounting_t walltime_accounting,
                t_inputrec *ir, PmeRunMode runMode);

/*! \brief Calculate the PME grid energy V for n charges.
 *
 * The potential (found in \p pme) must have been found already with a
 * call to gmx_pme_do() with at least GMX_PME_SPREAD and GMX_PME_SOLVE
 * specified. Note that the charges are not spread on the grid in the
 * pme struct. Currently does not work in parallel or with free
 * energy.
 */
void gmx_pme_calc_energy(gmx_pme_t                      *pme,
                         gmx::ArrayRef<const gmx::RVec>  x,
                         gmx::ArrayRef<const real>       q,
                         real                           *V);

/*! \brief Send the charges and maxshift to out PME-only node. */
void gmx_pme_send_parameters(const t_commrec *cr,
                             const interaction_const_t *ic,
                             gmx_bool bFreeEnergy_q, gmx_bool bFreeEnergy_lj,
                             real *chargeA, real *chargeB,
                             real *sqrt_c6A, real *sqrt_c6B,
                             real *sigmaA, real *sigmaB,
                             int maxshift_x, int maxshift_y);

/*! \brief Send the coordinates to our PME-only node and request a PME calculation */
void gmx_pme_send_coordinates(const t_commrec *cr, const matrix box, const rvec *x,
                              real lambda_q, real lambda_lj,
                              gmx_bool bEnerVir,
                              int64_t step, gmx_wallcycle *wcycle);

/*! \brief Tell our PME-only node to finish */
void gmx_pme_send_finish(const t_commrec *cr);

/*! \brief Tell our PME-only node to reset all cycle and flop counters */
void gmx_pme_send_resetcounters(const t_commrec *cr, int64_t step);

/*! \brief PP nodes receive the long range forces from the PME nodes */
void gmx_pme_receive_f(const t_commrec *cr,
                       gmx::ForceWithVirial *forceWithVirial,
                       real *energy_q, real *energy_lj,
                       real *dvdlambda_q, real *dvdlambda_lj,
                       float *pme_cycles);

/*! \brief
 * This function updates the local atom data on GPU after DD (charges, coordinates, etc.).
 * TODO: it should update the PME CPU atom data as well.
 * (currently PME CPU call gmx_pme_do() gets passed the input pointers for each computation).
 *
 * \param[in,out] pme        The PME structure.
 * \param[in]     numAtoms   The number of particles.
 * \param[in]     charges    The pointer to the array of particle charges.
 */
void gmx_pme_reinit_atoms(gmx_pme_t  *pme,
                          int         numAtoms,
                          const real *charges);

/* A block of PME GPU functions */

/*! \brief Checks whether the GROMACS build allows to run PME on GPU.
 * TODO: this partly duplicates an internal PME assert function
 * pme_gpu_check_restrictions(), except that works with a
 * formed gmx_pme_t structure. Should that one go away/work with inputrec?
 *
 * \param[out] error   If non-null, the error message when PME is not supported on GPU.
 *
 * \returns true if PME can run on GPU on this build, false otherwise.
 */
bool pme_gpu_supports_build(std::string *error);

/*! \brief Checks whether the detected (GPU) hardware allows to run PME on GPU.
 *
 * \param[in]  hwinfo  Information about the detected hardware
 * \param[out] error   If non-null, the error message when PME is not supported on GPU.
 *
 * \returns true if PME can run on GPU on this build, false otherwise.
 */
bool pme_gpu_supports_hardware(const gmx_hw_info_t &hwinfo,
                               std::string         *error);

/*! \brief Checks whether the input system allows to run PME on GPU.
 * TODO: this partly duplicates an internal PME assert function
 * pme_gpu_check_restrictions(), except that works with a
 * formed gmx_pme_t structure. Should that one go away/work with inputrec?
 *
 * \param[in]  ir     Input system.
 * \param[in]  mtop   Complete system topology to check if an FE simulation perturbs charges.
 * \param[out] error  If non-null, the error message if the input is not supported on GPU.
 *
 * \returns true if PME can run on GPU with this input, false otherwise.
 */
bool pme_gpu_supports_input(const t_inputrec &ir, const gmx_mtop_t &mtop, std::string *error);

/*! \brief
 * Returns the active PME codepath (CPU, GPU, mixed).
 * \todo This is a rather static data that should be managed by the higher level task scheduler.
 *
 * \param[in]  pme            The PME data structure.
 * \returns active PME codepath.
 */
PmeRunMode pme_run_mode(const gmx_pme_t *pme);

/*! \libinternal \brief
 * Return the pinning policy appropriate for this build configuration
 * for relevant buffers used for PME task on this rank (e.g. running
 * on a GPU). */
gmx::PinningPolicy pme_get_pinning_policy();

/*! \brief
 * Tells if PME is enabled to run on GPU (not necessarily active at the moment).
 * \todo This is a rather static data that should be managed by the hardware assignment manager.
 * For now, it is synonymous with the active PME codepath (in the absence of dynamic switching).
 *
 * \param[in]  pme            The PME data structure.
 * \returns true if PME can run on GPU, false otherwise.
 */
inline bool pme_gpu_task_enabled(const gmx_pme_t *pme)
{
    return (pme != nullptr) && (pme_run_mode(pme) != PmeRunMode::CPU);
}

/*! \brief Returns the size of the padding needed by GPU version of PME in the coordinates array.
 *
 * \param[in]  pme  The PME data structure.
 */
GPU_FUNC_QUALIFIER int pme_gpu_get_padding_size(const gmx_pme_t *GPU_FUNC_ARGUMENT(pme)) GPU_FUNC_TERM_WITH_RETURN(0);

// The following functions are all the PME GPU entry points,
// currently inlining to nothing on non-CUDA builds.

/*! \brief
 * Resets the PME GPU timings. To be called at the reset step.
 *
 * \param[in] pme            The PME structure.
 */
GPU_FUNC_QUALIFIER void pme_gpu_reset_timings(const gmx_pme_t *GPU_FUNC_ARGUMENT(pme)) GPU_FUNC_TERM;

/*! \brief
 * Copies the PME GPU timings to the gmx_wallclock_gpu_pme_t structure (for log output). To be called at the run end.
 *
 * \param[in] pme               The PME structure.
 * \param[in] timings           The gmx_wallclock_gpu_pme_t structure.
 */
GPU_FUNC_QUALIFIER void pme_gpu_get_timings(const gmx_pme_t         *GPU_FUNC_ARGUMENT(pme),
                                            gmx_wallclock_gpu_pme_t *GPU_FUNC_ARGUMENT(timings)) GPU_FUNC_TERM;

/* The main PME GPU functions */

/*! \brief
 * Prepares PME on GPU computation (updating the box if needed)
 * \param[in] pme               The PME data structure.
 * \param[in] needToUpdateBox   Tells if the stored unit cell parameters should be updated from \p box.
 * \param[in] box               The unit cell box.
 * \param[in] wcycle            The wallclock counter.
 * \param[in] flags             The combination of flags to affect this PME computation.
 *                              The flags are the GMX_PME_ flags from pme.h.
 * \param[in]  useGpuForceReduction Whether PME forces are reduced on GPU this step or should be downloaded for CPU reduction
 */
GPU_FUNC_QUALIFIER void pme_gpu_prepare_computation(gmx_pme_t      *GPU_FUNC_ARGUMENT(pme),
                                                    bool            GPU_FUNC_ARGUMENT(needToUpdateBox),
                                                    const matrix    GPU_FUNC_ARGUMENT(box),
                                                    gmx_wallcycle  *GPU_FUNC_ARGUMENT(wcycle),
                                                    int             GPU_FUNC_ARGUMENT(flags),
                                                    bool            GPU_FUNC_ARGUMENT(useGpuForceReduction)) GPU_FUNC_TERM;

/*! \brief
 * Launches H2D input transfers for PME on GPU.
 *
 * \param[in] pme               The PME data structure.
 * \param[in] coordinatesHost   The array of local atoms' coordinates.
 * \param[in] wcycle            The wallclock counter.
 */
GPU_FUNC_QUALIFIER void pme_gpu_copy_coordinates_to_gpu(gmx_pme_t            *GPU_FUNC_ARGUMENT(pme),
                                                        const rvec           *GPU_FUNC_ARGUMENT(coordinatesHost),
                                                        gmx_wallcycle        *GPU_FUNC_ARGUMENT(wcycle)) GPU_FUNC_TERM;

/*! \brief
 * Launches first stage of PME on GPU - spreading kernel, and D2H grid transfer if needed.
 *
 * \param[in] pme                The PME data structure.
 * \param[in] wcycle             The wallclock counter.
 */
GPU_FUNC_QUALIFIER void pme_gpu_launch_spread(gmx_pme_t           *GPU_FUNC_ARGUMENT(pme),
                                              gmx_wallcycle       *GPU_FUNC_ARGUMENT(wcycle)) GPU_FUNC_TERM;

/*! \brief
 * Launches middle stages of PME (FFT R2C, solving, FFT C2R) either on GPU or on CPU, depending on the run mode.
 *
 * \param[in] pme               The PME data structure.
 * \param[in] wcycle            The wallclock counter.
 */
GPU_FUNC_QUALIFIER void pme_gpu_launch_complex_transforms(gmx_pme_t       *GPU_FUNC_ARGUMENT(pme),
                                                          gmx_wallcycle   *GPU_FUNC_ARGUMENT(wcycle)) GPU_FUNC_TERM;

/*! \brief
 * Launches last stage of PME on GPU - force gathering and D2H force transfer.
 *
 * \param[in]  pme               The PME data structure.
 * \param[in]  wcycle            The wallclock counter.
 * \param[in]  forceTreatment    Tells how data should be treated. The gathering kernel either stores
 *                               the output reciprocal forces into the host array, or copies its contents to the GPU first
 *                               and accumulates. The reduction is non-atomic.
 */
GPU_FUNC_QUALIFIER void pme_gpu_launch_gather(const gmx_pme_t        *GPU_FUNC_ARGUMENT(pme),
                                              gmx_wallcycle          *GPU_FUNC_ARGUMENT(wcycle),
                                              PmeForceOutputHandling  GPU_FUNC_ARGUMENT(forceTreatment)) GPU_FUNC_TERM;

/*! \brief
 * Attempts to complete PME GPU tasks.
 *
 * The \p completionKind argument controls whether the function blocks until all
 * PME GPU tasks enqueued completed (as pme_gpu_wait_finish_task() does) or only
 * checks and returns immediately if they did not.
 * When blocking or the tasks have completed it also gets the output forces
 * by assigning the ArrayRef to the \p forces pointer passed in.
 * Virial/energy are also outputs if they were to be computed.
 *
 * \param[in]  pme            The PME data structure.
 * \param[in]  flags          The combination of flags to affect this PME computation.
 *                            The flags are the GMX_PME_ flags from pme.h.
 * \param[in]  wcycle         The wallclock counter.
 * \param[out] forceWithVirial The output force and virial
 * \param[out] enerd           The output energies
 * \param[in] flags            The combination of flags to affect this PME computation.
 *                             The flags are the GMX_PME_ flags from pme.h.
 * \param[in]  completionKind  Indicates whether PME task completion should only be checked rather than waited for
 * \returns                   True if the PME GPU tasks have completed
 */
GPU_FUNC_QUALIFIER bool
    pme_gpu_try_finish_task(gmx_pme_t            *GPU_FUNC_ARGUMENT(pme),
                            int                   GPU_FUNC_ARGUMENT(flags),
                            gmx_wallcycle        *GPU_FUNC_ARGUMENT(wcycle),
                            gmx::ForceWithVirial *GPU_FUNC_ARGUMENT(forceWithVirial),
                            gmx_enerdata_t       *GPU_FUNC_ARGUMENT(enerd),
                            GpuTaskCompletion     GPU_FUNC_ARGUMENT(completionKind)) GPU_FUNC_TERM_WITH_RETURN(false);

/*! \brief
 * Blocks until PME GPU tasks are completed, and gets the output forces and virial/energy
 * (if they were to be computed).
 *
 * \param[in]  pme             The PME data structure.
 * \param[in]  flags           The combination of flags to affect this PME computation.
 *                             The flags are the GMX_PME_ flags from pme.h.
 * \param[in]  wcycle          The wallclock counter.
 * \param[out] forceWithVirial The output force and virial
 * \param[out] enerd           The output energies
 */
GPU_FUNC_QUALIFIER void
    pme_gpu_wait_and_reduce(gmx_pme_t            *GPU_FUNC_ARGUMENT(pme),
                            int                   GPU_FUNC_ARGUMENT(flags),
                            gmx_wallcycle        *GPU_FUNC_ARGUMENT(wcycle),
                            gmx::ForceWithVirial *GPU_FUNC_ARGUMENT(forceWithVirial),
                            gmx_enerdata_t       *GPU_FUNC_ARGUMENT(enerd)) GPU_FUNC_TERM;

/*! \brief
 * The PME GPU reinitialization function that is called both at the end of any PME computation and on any load balancing.
 *
 * Clears the internal grid and energy/virial buffers; it is not safe to start
 * the PME computation without calling this.
 * Note that unlike in the nbnxn module, the force buffer does not need clearing.
 *
 * \todo Rename this function to *clear* -- it clearly only does output resetting
 * and we should be clear about what the function does..
 *
 * \param[in] pme            The PME data structure.
 * \param[in] wcycle         The wallclock counter.
 */
GPU_FUNC_QUALIFIER void pme_gpu_reinit_computation(const gmx_pme_t *GPU_FUNC_ARGUMENT(pme),
                                                   gmx_wallcycle   *GPU_FUNC_ARGUMENT(wcycle)) GPU_FUNC_TERM;


/*! \brief Get pointer to device copy of coordinate data.
 * \param[in] pme            The PME data structure.
 * \returns                  Pointer to coordinate data
 */
GPU_FUNC_QUALIFIER DeviceBuffer<float> pme_gpu_get_device_x(const gmx_pme_t *GPU_FUNC_ARGUMENT(pme)) GPU_FUNC_TERM_WITH_RETURN(DeviceBuffer<float> {});

/*! \brief Get pointer to device copy of force data.
 * \param[in] pme            The PME data structure.
 * \returns                  Pointer to force data
 */
GPU_FUNC_QUALIFIER void *pme_gpu_get_device_f(const gmx_pme_t *GPU_FUNC_ARGUMENT(pme)) GPU_FUNC_TERM_WITH_RETURN(nullptr);

/*! \brief Returns the pointer to the GPU stream.
 *  \param[in] pme            The PME data structure.
 *  \returns                  Pointer to GPU stream object.
 */
GPU_FUNC_QUALIFIER void *pme_gpu_get_device_stream(const gmx_pme_t *GPU_FUNC_ARGUMENT(pme)) GPU_FUNC_TERM_WITH_RETURN(nullptr);

/*! \brief Get pointer to the device synchronizer object that allows syncing on PME force calculation completion
 * \param[in] pme            The PME data structure.
 * \returns                  Pointer to sychronizer
 */
GPU_FUNC_QUALIFIER GpuEventSynchronizer *pme_gpu_get_f_ready_synchronizer(const gmx_pme_t *GPU_FUNC_ARGUMENT(pme)) GPU_FUNC_TERM_WITH_RETURN(nullptr);

#endif