Update instructions in containers.rst

[gromacs.git] / src / gromacs / taskassignment / decidegpuusage.h

/*
 * This file is part of the GROMACS molecular simulation package.
 *
 * Copyright (c) 2017,2018,2019,2020, 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.
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/*! \libinternal \file
 * \brief Declares functionality for deciding whether tasks will run on GPUs.
 *
 * \author Mark Abraham <mark.j.abraham@gmail.com>
 * \ingroup module_taskassignment
 * \inlibraryapi
 */

#ifndef GMX_TASKASSIGNMENT_DECIDEGPUUSAGE_H
#define GMX_TASKASSIGNMENT_DECIDEGPUUSAGE_H

#include <vector>

struct gmx_hw_info_t;
struct gmx_mtop_t;
struct t_inputrec;
enum class PmeRunMode;

namespace gmx
{

class MDLogger;

//! Record where a compute task is targetted.
enum class TaskTarget : int
{
    Auto,
    Cpu,
    Gpu
};

//! Help pass GPU-emulation parameters with type safety.
enum class EmulateGpuNonbonded : bool
{
    //! Do not emulate GPUs.
    No,
    //! Do emulate GPUs.
    Yes
};

/*! \libinternal
 *  \brief Structure that holds boolean flags corresponding to the development
 *        features present enabled through environment variables.
 *
 */
struct DevelopmentFeatureFlags
{
    //! True if the Buffer ops development feature is enabled
    // TODO: when the trigger of the buffer ops offload is fully automated this should go away
    bool enableGpuBufferOps = false;
    //! If true, forces 'mdrun -update auto' default to 'gpu'
    bool forceGpuUpdateDefault = false;
    //! True if the GPU halo exchange development feature is enabled
    bool enableGpuHaloExchange = false;
    //! True if the PME PP direct communication GPU development feature is enabled
    bool enableGpuPmePPComm = false;
};


class MDAtoms;

/*! \brief Decide whether this thread-MPI simulation will run
 * nonbonded tasks on GPUs.
 *
 * The number of GPU tasks and devices influences both the choice of
 * the number of ranks, and checks upon any such choice made by the
 * user. So we need to consider this before any automated choice of
 * the number of thread-MPI ranks.
 *
 * \param[in] nonbondedTarget              The user's choice for mdrun -nb for where to assign
 *                                         short-ranged nonbonded interaction tasks.
 * \param[in] numDevicesToUse              Number of compatible GPUs that the user permitted
 *                                         us to use.
 * \param[in] userGpuTaskAssignment        The user-specified assignment of GPU tasks to device IDs.
 * \param[in] emulateGpuNonbonded          Whether we will emulate GPU calculation of nonbonded
 *                                         interactions.
 * \param[in] buildSupportsNonbondedOnGpu  Whether GROMACS was built with GPU support.
 * \param[in] nonbondedOnGpuIsUseful       Whether computing nonbonded interactions on a GPU is
 *                                         useful for this calculation.
 * \param[in] numRanksPerSimulation        The number of ranks in each simulation.
 *
 * \returns    Whether the simulation will run nonbonded tasks on GPUs.
 *
 * \throws     std::bad_alloc          If out of memory
 *             InconsistentInputError  If the user requirements are inconsistent. */
bool decideWhetherToUseGpusForNonbondedWithThreadMpi(TaskTarget              nonbondedTarget,
                                                     int                     numDevicesToUse,
                                                     const std::vector<int>& userGpuTaskAssignment,
                                                     EmulateGpuNonbonded     emulateGpuNonbonded,
                                                     bool buildSupportsNonbondedOnGpu,
                                                     bool nonbondedOnGpuIsUseful,
                                                     int  numRanksPerSimulation);

/*! \brief Decide whether this thread-MPI simulation will run
 * PME tasks on GPUs.
 *
 * The number of GPU tasks and devices influences both the choice of
 * the number of ranks, and checks upon any such choice made by the
 * user. So we need to consider this before any automated choice of
 * the number of thread-MPI ranks.
 *
 * \param[in]  useGpuForNonbonded        Whether GPUs will be used for nonbonded interactions.
 * \param[in]  pmeTarget                 The user's choice for mdrun -pme for where to assign
 *                                       long-ranged PME nonbonded interaction tasks.
 * \param[in]  numDevicesToUse           The number of compatible GPUs that the user permitted us to use.
 * \param[in]  userGpuTaskAssignment     The user-specified assignment of GPU tasks to device IDs.
 * \param[in]  hardwareInfo              Hardware information
 * \param[in]  inputrec                  The user input
 * \param[in]  numRanksPerSimulation     The number of ranks in each simulation.
 * \param[in]  numPmeRanksPerSimulation  The number of PME ranks in each simulation.
 *
 * \returns    Whether the simulation will run PME tasks on GPUs.
 *
 * \throws     std::bad_alloc          If out of memory
 *             InconsistentInputError  If the user requirements are inconsistent. */
bool decideWhetherToUseGpusForPmeWithThreadMpi(bool                    useGpuForNonbonded,
                                               TaskTarget              pmeTarget,
                                               int                     numDevicesToUse,
                                               const std::vector<int>& userGpuTaskAssignment,
                                               const gmx_hw_info_t&    hardwareInfo,
                                               const t_inputrec&       inputrec,
                                               int                     numRanksPerSimulation,
                                               int                     numPmeRanksPerSimulation);

/*! \brief Decide whether the simulation will try to run nonbonded
 * tasks on GPUs.
 *
 * The final decision cannot be made until after the duty of the rank
 * is known. But we need to know if nonbonded will run on GPUs for
 * setting up DD (particularly rlist) and determining duty. If the
 * user requires GPUs for the tasks of that duty, then it will be an
 * error when none are found.
 *
 * With thread-MPI, calls have been made to
 * decideWhetherToUseGpusForNonbondedWithThreadMpi() and
 * decideWhetherToUseGpusForPmeWithThreadMpi() to help determine
 * the number of ranks and run some checks, but the final
 * decision is made in this routine, along with many more
 * consistency checks.
 *
 * \param[in]  nonbondedTarget             The user's choice for mdrun -nb for where to assign short-ranged nonbonded interaction tasks.
 * \param[in]  userGpuTaskAssignment       The user-specified assignment of GPU tasks to device IDs.
 * \param[in]  emulateGpuNonbonded         Whether we will emulate GPU calculation of nonbonded interactions.
 * \param[in]  buildSupportsNonbondedOnGpu Whether GROMACS was build with GPU support.
 * \param[in]  nonbondedOnGpuIsUseful      Whether computing nonbonded interactions on a GPU is useful for this calculation.
 * \param[in]  gpusWereDetected            Whether compatible GPUs were detected on any node.
 *
 * \returns    Whether the simulation will run nonbonded and PME tasks, respectively, on GPUs.
 *
 * \throws     std::bad_alloc          If out of memory
 *             InconsistentInputError  If the user requirements are inconsistent. */
bool decideWhetherToUseGpusForNonbonded(TaskTarget              nonbondedTarget,
                                        const std::vector<int>& userGpuTaskAssignment,
                                        EmulateGpuNonbonded     emulateGpuNonbonded,
                                        bool                    buildSupportsNonbondedOnGpu,
                                        bool                    nonbondedOnGpuIsUseful,
                                        bool                    gpusWereDetected);

/*! \brief Decide whether the simulation will try to run tasks of
 * different types on GPUs.
 *
 * The final decision cannot be made until after the duty of the rank
 * is known. But we need to know if nonbonded will run on GPUs for
 * setting up DD (particularly rlist) and determining duty. If the
 * user requires GPUs for the tasks of that duty, then it will be an
 * error when none are found.
 *
 * With thread-MPI, calls have been made to
 * decideWhetherToUseGpusForNonbondedWithThreadMpi() and
 * decideWhetherToUseGpusForPmeWithThreadMpi() to help determine
 * the number of ranks and run some checks, but the final
 * decision is made in this routine, along with many more
 * consistency checks.
 *
 * \param[in]  useGpuForNonbonded        Whether GPUs will be used for nonbonded interactions.
 * \param[in]  pmeTarget                 The user's choice for mdrun -pme for where to assign long-ranged PME nonbonded interaction tasks.
 * \param[in]  userGpuTaskAssignment     The user-specified assignment of GPU tasks to device IDs.
 * \param[in]  hardwareInfo              Hardware information
 * \param[in]  inputrec                  The user input
 * \param[in]  numRanksPerSimulation     The number of ranks in each simulation.
 * \param[in]  numPmeRanksPerSimulation  The number of PME ranks in each simulation.
 * \param[in]  gpusWereDetected          Whether compatible GPUs were detected on any node.
 *
 * \returns    Whether the simulation will run nonbonded and PME tasks, respectively, on GPUs.
 *
 * \throws     std::bad_alloc          If out of memory
 *             InconsistentInputError  If the user requirements are inconsistent. */
bool decideWhetherToUseGpusForPme(bool                    useGpuForNonbonded,
                                  TaskTarget              pmeTarget,
                                  const std::vector<int>& userGpuTaskAssignment,
                                  const gmx_hw_info_t&    hardwareInfo,
                                  const t_inputrec&       inputrec,
                                  int                     numRanksPerSimulation,
                                  int                     numPmeRanksPerSimulation,
                                  bool                    gpusWereDetected);

/*! \brief Determine PME run mode.
 *
 * Given the PME task assignment in \p useGpuForPme and the user-provided
 * FFT task target in \p pmeFftTarget, returns a PME run mode for the
 * current run. It also checks the compatibility of the two.
 *
 * \note Aborts the run upon incompatible values of \p useGpuForPme and \p pmeFftTarget.
 *
 * \param[in]  useGpuForPme              PME task assignment, true if PME task is mapped to the GPU.
 * \param[in]  pmeFftTarget              The user's choice for -pmefft for where to assign the FFT
 * work of the PME task. \param[in]  inputrec                  The user input record
 * */
PmeRunMode determinePmeRunMode(bool useGpuForPme, const TaskTarget& pmeFftTarget, const t_inputrec& inputrec);

/*! \brief Decide whether the simulation will try to run bonded tasks on GPUs.
 *
 * \param[in]  useGpuForNonbonded        Whether GPUs will be used for nonbonded interactions.
 * \param[in]  useGpuForPme              Whether GPUs will be used for PME interactions.
 * \param[in]  bondedTarget              The user's choice for mdrun -bonded for where to assign tasks.
 * \param[in]  inputrec                  The user input.
 * \param[in]  mtop                      The global topology.
 * \param[in]  numPmeRanksPerSimulation  The number of PME ranks in each simulation, can be -1 for auto.
 * \param[in]  gpusWereDetected          Whether compatible GPUs were detected on any node.
 *
 * \returns    Whether the simulation will run bondeded tasks on GPUs.
 *
 * \throws     std::bad_alloc          If out of memory
 *             InconsistentInputError  If the user requirements are inconsistent. */
bool decideWhetherToUseGpusForBonded(bool              useGpuForNonbonded,
                                     bool              useGpuForPme,
                                     TaskTarget        bondedTarget,
                                     const t_inputrec& inputrec,
                                     const gmx_mtop_t& mtop,
                                     int               numPmeRanksPerSimulation,
                                     bool              gpusWereDetected);

/*! \brief Decide whether to use GPU for update.
 *
 * \param[in]  isDomainDecomposition        Whether there more than one domain.
 * \param[in]  useUpdateGroups              If the constraints can be split across domains.
 * \param[in]  pmeRunMode                   PME running mode: CPU, GPU or mixed.
 * \param[in]  havePmeOnlyRank              If there is a PME-only rank in the simulation.
 * \param[in]  useGpuForNonbonded           Whether GPUs will be used for nonbonded interactions.
 * \param[in]  updateTarget                 User choice for running simulation on GPU.
 * \param[in]  gpusWereDetected             Whether compatible GPUs were detected on any node.
 * \param[in]  inputrec                     The user input.
 * \param[in]  mtop                         The global topology.
 * \param[in]  useEssentialDynamics         If essential dynamics is active.
 * \param[in]  doOrientationRestraints      If orientation restraints are enabled.
 * \param[in]  useReplicaExchange           If this is a REMD simulation.
 * \param[in]  doRerun                      It this is a rerun.
 * \param[in]  devFlags                     GPU development / experimental feature flags.
 * \param[in]  mdlog                        MD logger.
 *
 * \returns    Whether complete simulation can be run on GPU.
 * \throws     std::bad_alloc            If out of memory
 *             InconsistentInputError    If the user requirements are inconsistent.
 */
bool decideWhetherToUseGpuForUpdate(bool                           isDomainDecomposition,
                                    bool                           useUpdateGroups,
                                    PmeRunMode                     pmeRunMode,
                                    bool                           havePmeOnlyRank,
                                    bool                           useGpuForNonbonded,
                                    TaskTarget                     updateTarget,
                                    bool                           gpusWereDetected,
                                    const t_inputrec&              inputrec,
                                    const gmx_mtop_t&              mtop,
                                    bool                           useEssentialDynamics,
                                    bool                           doOrientationRestraints,
                                    bool                           useReplicaExchange,
                                    bool                           doRerun,
                                    const DevelopmentFeatureFlags& devFlags,
                                    const gmx::MDLogger&           mdlog);


/*! \brief Decide whether to use GPU for halo exchange.
 *
 * \param[in]  devFlags                     GPU development / experimental feature flags.
 * \param[in]  havePPDomainDecomposition    Whether PP domain decomposition is in use.
 * \param[in]  useGpuForNonbonded           Whether GPUs will be used for nonbonded interactions.
 * \param[in]  useModularSimulator          Whether modularsimulator is in use.
 * \param[in]  doRerun                      Whether this is a rerun.
 * \param[in]  haveEnergyMinimization       Whether energy minimization is in use.
 *
 * \returns    Whether halo exchange can be run on GPU.
 */
bool decideWhetherToUseGpuForHalo(const DevelopmentFeatureFlags& devFlags,
                                  bool                           havePPDomainDecomposition,
                                  bool                           useGpuForNonbonded,
                                  bool                           useModularSimulator,
                                  bool                           doRerun,
                                  bool                           haveEnergyMinimization);

} // namespace gmx

#endif