src/gromacs/mdlib/force.cpp

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  38 #include "gmxpre.h"
  39
  40 #include "force.h"
  41
  42 #include <cassert>
  43 #include <cmath>
  44 #include <cstring>
  45
  46 #include "gromacs/domdec/dlbtiming.h"
  47 #include "gromacs/domdec/domdec.h"
  48 #include "gromacs/domdec/domdec_struct.h"
  49 #include "gromacs/ewald/ewald.h"
  50 #include "gromacs/ewald/long_range_correction.h"
  51 #include "gromacs/ewald/pme.h"
  52 #include "gromacs/gmxlib/network.h"
  53 #include "gromacs/gmxlib/nrnb.h"
  54 #include "gromacs/math/vec.h"
  55 #include "gromacs/math/vecdump.h"
  56 #include "gromacs/mdlib/forcerec_threading.h"
  57 #include "gromacs/mdtypes/commrec.h"
  58 #include "gromacs/mdtypes/enerdata.h"
  59 #include "gromacs/mdtypes/forceoutput.h"
  60 #include "gromacs/mdtypes/forcerec.h"
  61 #include "gromacs/mdtypes/inputrec.h"
  62 #include "gromacs/mdtypes/interaction_const.h"
  63 #include "gromacs/mdtypes/md_enums.h"
  64 #include "gromacs/mdtypes/mdatom.h"
  65 #include "gromacs/mdtypes/simulation_workload.h"
  66 #include "gromacs/pbcutil/ishift.h"
  67 #include "gromacs/pbcutil/pbc.h"
  68 #include "gromacs/timing/wallcycle.h"
  69 #include "gromacs/utility/exceptions.h"
  70 #include "gromacs/utility/fatalerror.h"
  71 #include "gromacs/utility/smalloc.h"
  72
  73 using gmx::ArrayRef;
  74 using gmx::RVec;
  75
  76 static void clearEwaldThreadOutput(ewald_corr_thread_t* ewc_t)
  77 {
  78     ewc_t->Vcorr_q        = 0;
  79     ewc_t->Vcorr_lj       = 0;
  80     ewc_t->dvdl[efptCOUL] = 0;
  81     ewc_t->dvdl[efptVDW]  = 0;
  82     clear_mat(ewc_t->vir_q);
  83     clear_mat(ewc_t->vir_lj);
  84 }
  85
  86 static void reduceEwaldThreadOuput(int nthreads, ewald_corr_thread_t* ewc_t)
  87 {
  88     ewald_corr_thread_t& dest = ewc_t[0];
  89
  90     for (int t = 1; t < nthreads; t++)
  91     {
  92         dest.Vcorr_q += ewc_t[t].Vcorr_q;
  93         dest.Vcorr_lj += ewc_t[t].Vcorr_lj;
  94         dest.dvdl[efptCOUL] += ewc_t[t].dvdl[efptCOUL];
  95         dest.dvdl[efptVDW] += ewc_t[t].dvdl[efptVDW];
  96         m_add(dest.vir_q, ewc_t[t].vir_q, dest.vir_q);
  97         m_add(dest.vir_lj, ewc_t[t].vir_lj, dest.vir_lj);
  98     }
  99 }
 100
 101 void calculateLongRangeNonbondeds(t_forcerec*                   fr,
 102                                   const t_inputrec*             ir,
 103                                   const t_commrec*              cr,
 104                                   t_nrnb*                       nrnb,
 105                                   gmx_wallcycle_t               wcycle,
 106                                   const t_mdatoms*              md,
 107                                   gmx::ArrayRef<const RVec>     coordinates,
 108                                   gmx::ForceWithVirial*         forceWithVirial,
 109                                   gmx_enerdata_t*               enerd,
 110                                   const matrix                  box,
 111                                   const real*                   lambda,
 112                                   const rvec*                   mu_tot,
 113                                   const gmx::StepWorkload&      stepWork,
 114                                   const DDBalanceRegionHandler& ddBalanceRegionHandler)
 115 {
 116     const bool computePmeOnCpu = (EEL_PME(fr->ic->eeltype) || EVDW_PME(fr->ic->vdwtype))
 117                                  && thisRankHasDuty(cr, DUTY_PME)
 118                                  && (pme_run_mode(fr->pmedata) == PmeRunMode::CPU);
 119
 120     const bool haveEwaldSurfaceTerm = haveEwaldSurfaceContribution(*ir);
 121
 122     /* Do long-range electrostatics and/or LJ-PME
 123      * and compute PME surface terms when necessary.
 124      */
 125     if (computePmeOnCpu || fr->ic->eeltype == eelEWALD || haveEwaldSurfaceTerm)
 126     {
 127         int  status = 0;
 128         real Vlr_q = 0, Vlr_lj = 0;
 129
 130         /* We reduce all virial, dV/dlambda and energy contributions, except
 131          * for the reciprocal energies (Vlr_q, Vlr_lj) into the same struct.
 132          */
 133         ewald_corr_thread_t& ewaldOutput = fr->ewc_t[0];
 134         clearEwaldThreadOutput(&ewaldOutput);
 135
 136         if (EEL_PME_EWALD(fr->ic->eeltype) || EVDW_PME(fr->ic->vdwtype))
 137         {
 138             /* Calculate the Ewald surface force and energy contributions, when necessary */
 139             if (haveEwaldSurfaceTerm)
 140             {
 141                 wallcycle_sub_start(wcycle, ewcsEWALD_CORRECTION);
 142
 143                 int nthreads = fr->nthread_ewc;
 144 #pragma omp parallel for num_threads(nthreads) schedule(static)
 145                 for (int t = 0; t < nthreads; t++)
 146                 {
 147                     try
 148                     {
 149                         ewald_corr_thread_t& ewc_t = fr->ewc_t[t];
 150                         if (t > 0)
 151                         {
 152                             clearEwaldThreadOutput(&ewc_t);
 153                         }
 154
 155                         /* Threading is only supported with the Verlet cut-off
 156                          * scheme and then only single particle forces (no
 157                          * exclusion forces) are calculated, so we can store
 158                          * the forces in the normal, single forceWithVirial->force_ array.
 159                          */
 160                         const rvec* x = as_rvec_array(coordinates.data());
 161                         ewald_LRcorrection(md->homenr, cr, nthreads, t, *fr, *ir, md->chargeA,
 162                                            md->chargeB, (md->nChargePerturbed != 0), x, box, mu_tot,
 163                                            as_rvec_array(forceWithVirial->force_.data()),
 164                                            &ewc_t.Vcorr_q, lambda[efptCOUL], &ewc_t.dvdl[efptCOUL]);
 165                     }
 166                     GMX_CATCH_ALL_AND_EXIT_WITH_FATAL_ERROR
 167                 }
 168                 if (nthreads > 1)
 169                 {
 170                     reduceEwaldThreadOuput(nthreads, fr->ewc_t);
 171                 }
 172                 wallcycle_sub_stop(wcycle, ewcsEWALD_CORRECTION);
 173             }
 174
 175             if (EEL_PME_EWALD(fr->ic->eeltype) && fr->n_tpi == 0)
 176             {
 177                 /* This is not in a subcounter because it takes a
 178                    negligible and constant-sized amount of time */
 179                 ewaldOutput.Vcorr_q += ewald_charge_correction(
 180                         cr, fr, lambda[efptCOUL], box, &ewaldOutput.dvdl[efptCOUL], ewaldOutput.vir_q);
 181             }
 182
 183             if (computePmeOnCpu)
 184             {
 185                 /* Do reciprocal PME for Coulomb and/or LJ. */
 186                 assert(fr->n_tpi >= 0);
 187                 if (fr->n_tpi == 0 || stepWork.stateChanged)
 188                 {
 189                     /* With domain decomposition we close the CPU side load
 190                      * balancing region here, because PME does global
 191                      * communication that acts as a global barrier.
 192                      */
 193                     ddBalanceRegionHandler.closeAfterForceComputationCpu();
 194
 195                     wallcycle_start(wcycle, ewcPMEMESH);
 196                     status = gmx_pme_do(
 197                             fr->pmedata,
 198                             gmx::constArrayRefFromArray(coordinates.data(), md->homenr - fr->n_tpi),
 199                             forceWithVirial->force_, md->chargeA, md->chargeB, md->sqrt_c6A,
 200                             md->sqrt_c6B, md->sigmaA, md->sigmaB, box, cr,
 201                             DOMAINDECOMP(cr) ? dd_pme_maxshift_x(cr->dd) : 0,
 202                             DOMAINDECOMP(cr) ? dd_pme_maxshift_y(cr->dd) : 0, nrnb, wcycle,
 203                             ewaldOutput.vir_q, ewaldOutput.vir_lj, &Vlr_q, &Vlr_lj,
 204                             lambda[efptCOUL], lambda[efptVDW], &ewaldOutput.dvdl[efptCOUL],
 205                             &ewaldOutput.dvdl[efptVDW], stepWork);
 206                     wallcycle_stop(wcycle, ewcPMEMESH);
 207                     if (status != 0)
 208                     {
 209                         gmx_fatal(FARGS, "Error %d in reciprocal PME routine", status);
 210                     }
 211
 212                     /* We should try to do as little computation after
 213                      * this as possible, because parallel PME synchronizes
 214                      * the nodes, so we want all load imbalance of the
 215                      * rest of the force calculation to be before the PME
 216                      * call.  DD load balancing is done on the whole time
 217                      * of the force call (without PME).
 218                      */
 219                 }
 220                 if (fr->n_tpi > 0)
 221                 {
 222                     /* Determine the PME grid energy of the test molecule
 223                      * with the PME grid potential of the other charges.
 224                      */
 225                     gmx_pme_calc_energy(
 226                             fr->pmedata, coordinates.subArray(md->homenr - fr->n_tpi, fr->n_tpi),
 227                             gmx::arrayRefFromArray(md->chargeA + md->homenr - fr->n_tpi, fr->n_tpi),
 228                             &Vlr_q);
 229                 }
 230             }
 231         }
 232
 233         if (fr->ic->eeltype == eelEWALD)
 234         {
 235             const rvec* x = as_rvec_array(coordinates.data());
 236             Vlr_q = do_ewald(ir, x, as_rvec_array(forceWithVirial->force_.data()), md->chargeA,
 237                              md->chargeB, box, cr, md->homenr, ewaldOutput.vir_q, fr->ic->ewaldcoeff_q,
 238                              lambda[efptCOUL], &ewaldOutput.dvdl[efptCOUL], fr->ewald_table);
 239         }
 240
 241         /* Note that with separate PME nodes we get the real energies later */
 242         // TODO it would be simpler if we just accumulated a single
 243         // long-range virial contribution.
 244         forceWithVirial->addVirialContribution(ewaldOutput.vir_q);
 245         forceWithVirial->addVirialContribution(ewaldOutput.vir_lj);
 246         enerd->dvdl_lin[efptCOUL] += ewaldOutput.dvdl[efptCOUL];
 247         enerd->dvdl_lin[efptVDW] += ewaldOutput.dvdl[efptVDW];
 248         enerd->term[F_COUL_RECIP] = Vlr_q + ewaldOutput.Vcorr_q;
 249         enerd->term[F_LJ_RECIP]   = Vlr_lj + ewaldOutput.Vcorr_lj;
 250
 251         if (debug)
 252         {
 253             fprintf(debug, "Vlr_q = %g, Vcorr_q = %g, Vlr_corr_q = %g\n", Vlr_q,
 254                     ewaldOutput.Vcorr_q, enerd->term[F_COUL_RECIP]);
 255             pr_rvecs(debug, 0, "vir_el_recip after corr", ewaldOutput.vir_q, DIM);
 256             fprintf(debug, "Vlr_lj: %g, Vcorr_lj = %g, Vlr_corr_lj = %g\n", Vlr_lj,
 257                     ewaldOutput.Vcorr_lj, enerd->term[F_LJ_RECIP]);
 258             pr_rvecs(debug, 0, "vir_lj_recip after corr", ewaldOutput.vir_lj, DIM);
 259         }
 260     }
 261
 262     if (debug)
 263     {
 264         print_nrnb(debug, nrnb);
 265     }
 266 }