src/gromacs/domdec/domdec_setup.h

   1 /*
   2  * This file is part of the GROMACS molecular simulation package.
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   4  * Copyright (c) 2019,2020, by the GROMACS development team, led by
   5  * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
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  35 /*! \internal \file
  36  *
  37  * \brief Declares functions for choosing the DD grid setup
  38  *
  39  * \author Berk Hess <hess@kth.se>
  40  * \ingroup module_domdec
  41  */
  42 #ifndef GMX_DOMDEC_DOMDEC_SETUP_H
  43 #define GMX_DOMDEC_DOMDEC_SETUP_H
  44
  45 #include "gromacs/math/vec.h"
  46 #include "gromacs/utility/gmxmpi.h"
  47
  48 enum class DDRole;
  49 struct DDSettings;
  50 struct DDSystemInfo;
  51 struct gmx_ddbox_t;
  52 struct gmx_mtop_t;
  53 struct t_commrec;
  54 struct t_inputrec;
  55
  56 namespace gmx
  57 {
  58 struct DomdecOptions;
  59 class MDLogger;
  60 template<typename T>
  61 class ArrayRef;
  62 } // namespace gmx
  63
  64 /*! \brief Returns the volume fraction of the system that is communicated */
  65 real comm_box_frac(const gmx::IVec& dd_nc, real cutoff, const gmx_ddbox_t& ddbox);
  66
  67 /*! \internal
  68  * \brief Describes the DD grid setup
  69  *
  70  * This struct is for temporary use when choosing and initializing
  71  * the domain decomposition grid.
  72  */
  73 struct DDGridSetup
  74 {
  75     //! The number of separate PME ranks, 0 if none or all ranks do PME
  76     int numPmeOnlyRanks = 0;
  77     //! The number of domains along each dimension
  78     ivec numDomains = { 0, 0, 0 };
  79     //! The number of dimensions which we decompose in domains
  80     int numDDDimensions = 0;
  81     //! The domain decomposition dimensions, the first numDDDimensions entries are used
  82     ivec ddDimensions = { -1, -1, -1 };
  83 };
  84
  85 /*! \brief Checks that requests for PP and PME ranks honor basic expectations
  86  *
  87  * Issues a fatal error if there are more PME ranks than PP, or if the
  88  * count of PP ranks has a prime factor that is too large to be likely
  89  * to have good performance. */
  90 void checkForValidRankCountRequests(int  numRanksRequested,
  91                                     bool usingPme,
  92                                     int  numPmeRanksRequested,
  93                                     bool checkForLargePrimeFactors);
  94
  95 /*! \brief Return the minimum cell size (in nm) required for DD */
  96 real getDDGridSetupCellSizeLimit(const gmx::MDLogger& mdlog,
  97                                  bool                 bDynLoadBal,
  98                                  real                 dlb_scale,
  99                                  const t_inputrec&    ir,
 100                                  real                 systemInfoCellSizeLimit);
 101
 102 /*! \brief Determines the DD grid setup
 103  *
 104  * Either implements settings required by the user, or otherwise
 105  * chooses estimated optimal number of separate PME ranks and DD grid
 106  * cell setup, DD cell size limits, and the initial ddbox.
 107  */
 108 DDGridSetup getDDGridSetup(const gmx::MDLogger&           mdlog,
 109                            DDRole                         ddRole,
 110                            MPI_Comm                       communicator,
 111                            int                            numRanksRequested,
 112                            const gmx::DomdecOptions&      options,
 113                            const DDSettings&              ddSettings,
 114                            const DDSystemInfo&            systemInfo,
 115                            real                           cellSizeLimit,
 116                            const gmx_mtop_t&              mtop,
 117                            const t_inputrec&              ir,
 118                            const matrix                   box,
 119                            gmx::ArrayRef<const gmx::RVec> xGlobal,
 120                            gmx_ddbox_t*                   ddbox);
 121
 122 #endif