src/gromacs/domdec/cellsizes.cpp

   1 /*
   2  * This file is part of the GROMACS molecular simulation package.
   3  *
   4  * Copyright (c) 2018, by the GROMACS development team, led by
   5  * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
   6  * and including many others, as listed in the AUTHORS file in the
   7  * top-level source directory and at http://www.gromacs.org.
   8  *
   9  * GROMACS is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public License
  11  * as published by the Free Software Foundation; either version 2.1
  12  * of the License, or (at your option) any later version.
  13  *
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  35 /* \internal \file
  36  *
  37  * \brief Implements DD cell-size related functions.
  38  *
  39  * \author Berk Hess <hess@kth.se>
  40  * \author Roland Schulz <roland.schulz@intel.com>
  41  * \ingroup module_domdec
  42  */
  43
  44 #include "gmxpre.h"
  45
  46 #include "cellsizes.h"
  47
  48 #include "config.h"
  49
  50 #include "gromacs/gmxlib/network.h"
  51 #include "gromacs/math/vec.h"
  52 #include "gromacs/mdtypes/commrec.h"
  53 #include "gromacs/utility/cstringutil.h"
  54 #include "gromacs/utility/fatalerror.h"
  55
  56 #include "atomdistribution.h"
  57 #include "domdec_internal.h"
  58 #include "utility.h"
  59
  60 static void set_pme_maxshift(gmx_domdec_t *dd, gmx_ddpme_t *ddpme,
  61                              gmx_bool bUniform, const gmx_ddbox_t *ddbox,
  62                              const real *cellFrac)
  63 {
  64     gmx_domdec_comm_t *comm;
  65     int                nc, ns, s;
  66     int               *xmin, *xmax;
  67     real               range, pme_boundary;
  68     int                sh;
  69
  70     comm = dd->comm;
  71     nc   = dd->nc[ddpme->dim];
  72     ns   = ddpme->nslab;
  73
  74     if (!ddpme->dim_match)
  75     {
  76         /* PP decomposition is not along dim: the worst situation */
  77         sh = ns/2;
  78     }
  79     else if (ns <= 3 || (bUniform && ns == nc))
  80     {
  81         /* The optimal situation */
  82         sh = 1;
  83     }
  84     else
  85     {
  86         /* We need to check for all pme nodes which nodes they
  87          * could possibly need to communicate with.
  88          */
  89         xmin = ddpme->pp_min;
  90         xmax = ddpme->pp_max;
  91         /* Allow for atoms to be maximally 2/3 times the cut-off
  92          * out of their DD cell. This is a reasonable balance between
  93          * between performance and support for most charge-group/cut-off
  94          * combinations.
  95          */
  96         range  = 2.0/3.0*comm->cutoff/ddbox->box_size[ddpme->dim];
  97         /* Avoid extra communication when we are exactly at a boundary */
  98         range *= 0.999;
  99
 100         sh = 1;
 101         for (s = 0; s < ns; s++)
 102         {
 103             /* PME slab s spreads atoms between box frac. s/ns and (s+1)/ns */
 104             pme_boundary = static_cast<real>(s)/ns;
 105             while (sh + 1 < ns &&
 106                    ((s - (sh + 1) >= 0 &&
 107                      cellFrac[xmax[s - (sh + 1)     ] + 1]     + range > pme_boundary) ||
 108                     (s - (sh + 1) <  0 &&
 109                      cellFrac[xmax[s - (sh + 1) + ns] + 1] - 1 + range > pme_boundary)))
 110             {
 111                 sh++;
 112             }
 113             pme_boundary = static_cast<real>(s+1)/ns;
 114             while (sh + 1 < ns &&
 115                    ((s + (sh + 1) <  ns &&
 116                      cellFrac[xmin[s + (sh + 1)    ]  ]     - range < pme_boundary) ||
 117                     (s + (sh + 1) >= ns &&
 118                      cellFrac[xmin[s +(sh + 1) - ns]  ] + 1 - range < pme_boundary)))
 119             {
 120                 sh++;
 121             }
 122         }
 123     }
 124
 125     ddpme->maxshift = sh;
 126
 127     if (debug)
 128     {
 129         fprintf(debug, "PME slab communication range for dim %d is %d\n",
 130                 ddpme->dim, ddpme->maxshift);
 131     }
 132 }
 133
 134 static void check_box_size(const gmx_domdec_t *dd,
 135                            const gmx_ddbox_t  *ddbox)
 136 {
 137     int d, dim;
 138
 139     for (d = 0; d < dd->ndim; d++)
 140     {
 141         dim = dd->dim[d];
 142         if (dim < ddbox->nboundeddim &&
 143             ddbox->box_size[dim]*ddbox->skew_fac[dim] <
 144             dd->nc[dim]*dd->comm->cellsize_limit*DD_CELL_MARGIN)
 145         {
 146             gmx_fatal(FARGS, "The %c-size of the box (%f) times the triclinic skew factor (%f) is smaller than the number of DD cells (%d) times the smallest allowed cell size (%f)\n",
 147                       dim2char(dim), ddbox->box_size[dim], ddbox->skew_fac[dim],
 148                       dd->nc[dim], dd->comm->cellsize_limit);
 149         }
 150     }
 151 }
 152
 153 real grid_jump_limit(const gmx_domdec_comm_t *comm,
 154                      real                     cutoff,
 155                      int                      dim_ind)
 156 {
 157     real grid_jump_limit;
 158
 159     /* The distance between the boundaries of cells at distance
 160      * x+-1,y+-1 or y+-1,z+-1 is limited by the cut-off restrictions
 161      * and by the fact that cells should not be shifted by more than
 162      * half their size, such that cg's only shift by one cell
 163      * at redecomposition.
 164      */
 165     grid_jump_limit = comm->cellsize_limit;
 166     if (!comm->bVacDLBNoLimit)
 167     {
 168         if (comm->bPMELoadBalDLBLimits)
 169         {
 170             cutoff = std::max(cutoff, comm->PMELoadBal_max_cutoff);
 171         }
 172         grid_jump_limit = std::max(grid_jump_limit,
 173                                    cutoff/comm->cd[dim_ind].numPulses());
 174     }
 175
 176     return grid_jump_limit;
 177 }
 178
 179 /* This function should be used for moving the domain boudaries during DLB,
 180  * for obtaining the minimum cell size. It checks the initially set limit
 181  * comm->cellsize_min, for bonded and initial non-bonded cut-offs,
 182  * and, possibly, a longer cut-off limit set for PME load balancing.
 183  */
 184 static real cellsize_min_dlb(gmx_domdec_comm_t *comm, int dim_ind, int dim)
 185 {
 186     real cellsize_min;
 187
 188     cellsize_min = comm->cellsize_min[dim];
 189
 190     if (!comm->bVacDLBNoLimit)
 191     {
 192         /* The cut-off might have changed, e.g. by PME load balacning,
 193          * from the value used to set comm->cellsize_min, so check it.
 194          */
 195         cellsize_min = std::max(cellsize_min, comm->cutoff/comm->cd[dim_ind].np_dlb);
 196
 197         if (comm->bPMELoadBalDLBLimits)
 198         {
 199             /* Check for the cut-off limit set by the PME load balancing */
 200             cellsize_min = std::max(cellsize_min, comm->PMELoadBal_max_cutoff/comm->cd[dim_ind].np_dlb);
 201         }
 202     }
 203
 204     return cellsize_min;
 205 }
 206
 207 /* Set the domain boundaries. Use for static (or no) load balancing,
 208  * and also for the starting state for dynamic load balancing.
 209  * setmode determine if and where the boundaries are stored, use enum above.
 210  * Returns the number communication pulses in npulse.
 211  */
 212 gmx::ArrayRef < const std::vector < real>>
 213 set_dd_cell_sizes_slb(gmx_domdec_t *dd, const gmx_ddbox_t *ddbox,
 214                       int setmode, ivec npulse)
 215 {
 216     gmx_domdec_comm_t *comm = dd->comm;
 217
 218     gmx::ArrayRef < std::vector < real>> cell_x_master;
 219     if (setmode == setcellsizeslbMASTER)
 220     {
 221         cell_x_master = dd->ma->cellSizesBuffer;
 222     }
 223
 224     rvec cellsize_min;
 225     for (int d = 0; d < DIM; d++)
 226     {
 227         cellsize_min[d] = ddbox->box_size[d]*ddbox->skew_fac[d];
 228         npulse[d]       = 1;
 229         if (dd->nc[d] == 1 || comm->slb_frac[d] == nullptr)
 230         {
 231             /* Uniform grid */
 232             real cell_dx = ddbox->box_size[d]/dd->nc[d];
 233             switch (setmode)
 234             {
 235                 case setcellsizeslbMASTER:
 236                     for (int j = 0; j < dd->nc[d]+1; j++)
 237                     {
 238                         cell_x_master[d][j] = ddbox->box0[d] + j*cell_dx;
 239                     }
 240                     break;
 241                 case setcellsizeslbLOCAL:
 242                     comm->cell_x0[d] = ddbox->box0[d] + (dd->ci[d]  )*cell_dx;
 243                     comm->cell_x1[d] = ddbox->box0[d] + (dd->ci[d]+1)*cell_dx;
 244                     break;
 245                 default:
 246                     break;
 247             }
 248             real cellsize = cell_dx*ddbox->skew_fac[d];
 249             while (cellsize*npulse[d] < comm->cutoff)
 250             {
 251                 npulse[d]++;
 252             }
 253             cellsize_min[d] = cellsize;
 254         }
 255         else
 256         {
 257             /* Statically load balanced grid */
 258             /* Also when we are not doing a master distribution we determine
 259              * all cell borders in a loop to obtain identical values
 260              * to the master distribution case and to determine npulse.
 261              */
 262             gmx::ArrayRef<real> cell_x;
 263             std::vector<real>   cell_x_buffer;
 264             if (setmode == setcellsizeslbMASTER)
 265             {
 266                 cell_x = cell_x_master[d];
 267             }
 268             else
 269             {
 270                 cell_x_buffer.resize(dd->nc[d] + 1);
 271                 cell_x = cell_x_buffer;
 272             }
 273             cell_x[0] = ddbox->box0[d];
 274             for (int j = 0; j < dd->nc[d]; j++)
 275             {
 276                 real cell_dx  = ddbox->box_size[d]*comm->slb_frac[d][j];
 277                 cell_x[j+1]   = cell_x[j] + cell_dx;
 278                 real cellsize = cell_dx*ddbox->skew_fac[d];
 279                 while (cellsize*npulse[d] < comm->cutoff &&
 280                        npulse[d] < dd->nc[d]-1)
 281                 {
 282                     npulse[d]++;
 283                 }
 284                 cellsize_min[d] = std::min(cellsize_min[d], cellsize);
 285             }
 286             if (setmode == setcellsizeslbLOCAL)
 287             {
 288                 comm->cell_x0[d] = cell_x[dd->ci[d]];
 289                 comm->cell_x1[d] = cell_x[dd->ci[d]+1];
 290             }
 291         }
 292         /* The following limitation is to avoid that a cell would receive
 293          * some of its own home charge groups back over the periodic boundary.
 294          * Double charge groups cause trouble with the global indices.
 295          */
 296         if (d < ddbox->npbcdim &&
 297             dd->nc[d] > 1 && npulse[d] >= dd->nc[d])
 298         {
 299             char error_string[STRLEN];
 300
 301             sprintf(error_string,
 302                     "The box size in direction %c (%f) times the triclinic skew factor (%f) is too small for a cut-off of %f with %d domain decomposition cells, use 1 or more than %d %s or increase the box size in this direction",
 303                     dim2char(d), ddbox->box_size[d], ddbox->skew_fac[d],
 304                     comm->cutoff,
 305                     dd->nc[d], dd->nc[d],
 306                     dd->nnodes > dd->nc[d] ? "cells" : "ranks");
 307
 308             if (setmode == setcellsizeslbLOCAL)
 309             {
 310                 gmx_fatal_collective(FARGS, dd->mpi_comm_all, DDMASTER(dd),
 311                                      "%s", error_string);
 312             }
 313             else
 314             {
 315                 gmx_fatal(FARGS, "%s", error_string);
 316             }
 317         }
 318     }
 319
 320     if (!isDlbOn(comm))
 321     {
 322         copy_rvec(cellsize_min, comm->cellsize_min);
 323     }
 324
 325     for (int d = 0; d < comm->npmedecompdim; d++)
 326     {
 327         set_pme_maxshift(dd, &comm->ddpme[d],
 328                          comm->slb_frac[dd->dim[d]] == nullptr, ddbox,
 329                          comm->ddpme[d].slb_dim_f);
 330     }
 331
 332     return cell_x_master;
 333 }
 334
 335
 336 static void dd_cell_sizes_dlb_root_enforce_limits(gmx_domdec_t *dd,
 337                                                   int d, int dim, RowMaster *rowMaster,
 338                                                   const gmx_ddbox_t *ddbox,
 339                                                   gmx_bool bUniform, int64_t step, real cellsize_limit_f, int range[])
 340 {
 341     gmx_domdec_comm_t *comm;
 342     real               halfway, cellsize_limit_f_i, region_size;
 343     gmx_bool           bLastHi  = FALSE;
 344     int                nrange[] = {range[0], range[1]};
 345
 346     region_size = rowMaster->cellFrac[range[1]] - rowMaster->cellFrac[range[0]];
 347
 348     comm = dd->comm;
 349
 350     const int           ncd       = dd->nc[dim];
 351
 352     const bool          dimHasPbc = (dim < ddbox->npbcdim);
 353
 354     gmx::ArrayRef<real> cell_size = rowMaster->buf_ncd;
 355
 356     if (debug)
 357     {
 358         fprintf(debug, "enforce_limits: %d %d\n", range[0], range[1]);
 359     }
 360
 361     /* First we need to check if the scaling does not make cells
 362      * smaller than the smallest allowed size.
 363      * We need to do this iteratively, since if a cell is too small,
 364      * it needs to be enlarged, which makes all the other cells smaller,
 365      * which could in turn make another cell smaller than allowed.
 366      */
 367     for (int i = range[0]; i < range[1]; i++)
 368     {
 369         rowMaster->isCellMin[i] = false;
 370     }
 371     int nmin = 0;
 372     int nmin_old;
 373     do
 374     {
 375         nmin_old = nmin;
 376         /* We need the total for normalization */
 377         real fac = 0;
 378         for (int i = range[0]; i < range[1]; i++)
 379         {
 380             if (!rowMaster->isCellMin[i])
 381             {
 382                 fac += cell_size[i];
 383             }
 384         }
 385         fac = ( region_size - nmin*cellsize_limit_f)/fac; /* substracting cells already set to cellsize_limit_f */
 386         /* Determine the cell boundaries */
 387         for (int i = range[0]; i < range[1]; i++)
 388         {
 389             if (!rowMaster->isCellMin[i])
 390             {
 391                 cell_size[i] *= fac;
 392                 if (!dimHasPbc && (i == 0 || i == dd->nc[dim] - 1))
 393                 {
 394                     cellsize_limit_f_i = 0;
 395                 }
 396                 else
 397                 {
 398                     cellsize_limit_f_i = cellsize_limit_f;
 399                 }
 400                 if (cell_size[i] < cellsize_limit_f_i)
 401                 {
 402                     rowMaster->isCellMin[i] = true;
 403                     cell_size[i]            = cellsize_limit_f_i;
 404                     nmin++;
 405                 }
 406             }
 407             rowMaster->cellFrac[i + 1] = rowMaster->cellFrac[i] + cell_size[i];
 408         }
 409     }
 410     while (nmin > nmin_old);
 411
 412     const int i  = range[1] - 1;
 413     cell_size[i] = rowMaster->cellFrac[i + 1] - rowMaster->cellFrac[i];
 414     /* For this check we should not use DD_CELL_MARGIN,
 415      * but a slightly smaller factor,
 416      * since rounding could get use below the limit.
 417      */
 418     if (dimHasPbc &&
 419         cell_size[i] < cellsize_limit_f*DD_CELL_MARGIN2/DD_CELL_MARGIN)
 420     {
 421         char buf[22];
 422         gmx_fatal(FARGS, "step %s: the dynamic load balancing could not balance dimension %c: box size %f, triclinic skew factor %f, #cells %d, minimum cell size %f\n",
 423                   gmx_step_str(step, buf),
 424                   dim2char(dim), ddbox->box_size[dim], ddbox->skew_fac[dim],
 425                   ncd, comm->cellsize_min[dim]);
 426     }
 427
 428     rowMaster->dlbIsLimited = (nmin > 0) || (range[0] > 0) || (range[1] < ncd);
 429
 430     if (!bUniform)
 431     {
 432         /* Check if the boundary did not displace more than halfway
 433          * each of the cells it bounds, as this could cause problems,
 434          * especially when the differences between cell sizes are large.
 435          * If changes are applied, they will not make cells smaller
 436          * than the cut-off, as we check all the boundaries which
 437          * might be affected by a change and if the old state was ok,
 438          * the cells will at most be shrunk back to their old size.
 439          */
 440         for (int i = range[0]+1; i < range[1]; i++)
 441         {
 442             halfway = 0.5*(rowMaster->oldCellFrac[i] + rowMaster->oldCellFrac[i - 1]);
 443             if (rowMaster->cellFrac[i] < halfway)
 444             {
 445                 rowMaster->cellFrac[i] = halfway;
 446                 /* Check if the change also causes shifts of the next boundaries */
 447                 for (int j = i + 1; j < range[1]; j++)
 448                 {
 449                     if (rowMaster->cellFrac[j] < rowMaster->cellFrac[j - 1] + cellsize_limit_f)
 450                     {
 451                         rowMaster->cellFrac[j] =  rowMaster->cellFrac[j - 1] + cellsize_limit_f;
 452                     }
 453                 }
 454             }
 455             halfway = 0.5*(rowMaster->oldCellFrac[i] + rowMaster->oldCellFrac[i + 1]);
 456             if (rowMaster->cellFrac[i] > halfway)
 457             {
 458                 rowMaster->cellFrac[i] = halfway;
 459                 /* Check if the change also causes shifts of the next boundaries */
 460                 for (int j = i - 1; j >= range[0] + 1; j--)
 461                 {
 462                     if (rowMaster->cellFrac[j] > rowMaster->cellFrac[j + 1] - cellsize_limit_f)
 463                     {
 464                         rowMaster->cellFrac[j] = rowMaster->cellFrac[j + 1] - cellsize_limit_f;
 465                     }
 466                 }
 467             }
 468         }
 469     }
 470
 471     /* nrange is defined as [lower, upper) range for new call to enforce_limits */
 472     /* find highest violation of LimLo (a) and the following violation of LimHi (thus the lowest following) (b)
 473      * then call enforce_limits for (oldb,a), (a,b). In the next step: (b,nexta). oldb and nexta can be the boundaries.
 474      * for a and b nrange is used */
 475     if (d > 0)
 476     {
 477         /* Take care of the staggering of the cell boundaries */
 478         if (bUniform)
 479         {
 480             for (int i = range[0]; i < range[1]; i++)
 481             {
 482                 rowMaster->bounds[i].cellFracLowerMax = rowMaster->cellFrac[i];
 483                 rowMaster->bounds[i].cellFracUpperMin = rowMaster->cellFrac[i + 1];
 484             }
 485         }
 486         else
 487         {
 488             for (int i = range[0] + 1; i < range[1]; i++)
 489             {
 490                 const RowMaster::Bounds &bounds = rowMaster->bounds[i];
 491
 492                 bool                     bLimLo = (rowMaster->cellFrac[i] < bounds.boundMin);
 493                 bool                     bLimHi = (rowMaster->cellFrac[i] > bounds.boundMax);
 494                 if (bLimLo && bLimHi)
 495                 {
 496                     /* Both limits violated, try the best we can */
 497                     /* For this case we split the original range (range) in two parts and care about the other limitiations in the next iteration. */
 498                     rowMaster->cellFrac[i] = 0.5*(bounds.boundMin + bounds.boundMax);
 499                     nrange[0]              = range[0];
 500                     nrange[1]              = i;
 501                     dd_cell_sizes_dlb_root_enforce_limits(dd, d, dim, rowMaster, ddbox, bUniform, step, cellsize_limit_f, nrange);
 502
 503                     nrange[0] = i;
 504                     nrange[1] = range[1];
 505                     dd_cell_sizes_dlb_root_enforce_limits(dd, d, dim, rowMaster, ddbox, bUniform, step, cellsize_limit_f, nrange);
 506
 507                     return;
 508                 }
 509                 else if (bLimLo)
 510                 {
 511                     /* rowMaster->cellFrac[i] = rowMaster->boundMin[i]; */
 512                     nrange[1] = i;  /* only store violation location. There could be a LimLo violation following with an higher index */
 513                     bLastHi   = FALSE;
 514                 }
 515                 else if (bLimHi && !bLastHi)
 516                 {
 517                     bLastHi = TRUE;
 518                     if (nrange[1] < range[1])   /* found a LimLo before */
 519                     {
 520                         rowMaster->cellFrac[nrange[1]] = rowMaster->bounds[1].boundMin;
 521                         dd_cell_sizes_dlb_root_enforce_limits(dd, d, dim, rowMaster, ddbox, bUniform, step, cellsize_limit_f, nrange);
 522                         nrange[0] = nrange[1];
 523                     }
 524                     rowMaster->cellFrac[i] = rowMaster->bounds[i].boundMax;
 525                     nrange[1]              = i;
 526                     dd_cell_sizes_dlb_root_enforce_limits(dd, d, dim, rowMaster, ddbox, bUniform, step, cellsize_limit_f, nrange);
 527                     nrange[0] = i;
 528                     nrange[1] = range[1];
 529                 }
 530             }
 531             if (nrange[1] < range[1])   /* found last a LimLo */
 532             {
 533                 rowMaster->cellFrac[nrange[1]] = rowMaster->bounds[nrange[1]].boundMin;
 534                 dd_cell_sizes_dlb_root_enforce_limits(dd, d, dim, rowMaster, ddbox, bUniform, step, cellsize_limit_f, nrange);
 535                 nrange[0] = nrange[1];
 536                 nrange[1] = range[1];
 537                 dd_cell_sizes_dlb_root_enforce_limits(dd, d, dim, rowMaster, ddbox, bUniform, step, cellsize_limit_f, nrange);
 538             }
 539             else if (nrange[0] > range[0]) /* found at least one LimHi */
 540             {
 541                 dd_cell_sizes_dlb_root_enforce_limits(dd, d, dim, rowMaster, ddbox, bUniform, step, cellsize_limit_f, nrange);
 542             }
 543         }
 544     }
 545 }
 546
 547
 548 static void set_dd_cell_sizes_dlb_root(gmx_domdec_t *dd,
 549                                        int d, int dim, RowMaster *rowMaster,
 550                                        const gmx_ddbox_t *ddbox,
 551                                        gmx_bool bDynamicBox,
 552                                        gmx_bool bUniform, int64_t step)
 553 {
 554     gmx_domdec_comm_t *comm    = dd->comm;
 555     constexpr real     c_relax = 0.5;
 556     int                range[] = { 0, 0 };
 557
 558     /* Convert the maximum change from the input percentage to a fraction */
 559     const real          change_limit = comm->dlb_scale_lim*0.01;
 560
 561     const int           ncd          = dd->nc[dim];
 562
 563     const bool          bPBC = (dim < ddbox->npbcdim);
 564
 565     gmx::ArrayRef<real> cell_size = rowMaster->buf_ncd;
 566
 567     /* Store the original boundaries */
 568     for (int i = 0; i < ncd + 1; i++)
 569     {
 570         rowMaster->oldCellFrac[i] = rowMaster->cellFrac[i];
 571     }
 572     if (bUniform)
 573     {
 574         for (int i = 0; i < ncd; i++)
 575         {
 576             cell_size[i] = 1.0/ncd;
 577         }
 578     }
 579     else if (dd_load_count(comm) > 0)
 580     {
 581         real load_aver  = comm->load[d].sum_m/ncd;
 582         real change_max = 0;
 583         real load_i;
 584         real change;
 585         for (int i = 0; i < ncd; i++)
 586         {
 587             /* Determine the relative imbalance of cell i */
 588             load_i         = comm->load[d].load[i*comm->load[d].nload+2];
 589             real imbalance = (load_i - load_aver)/(load_aver > 0 ? load_aver : 1);
 590             /* Determine the change of the cell size using underrelaxation */
 591             change     = -c_relax*imbalance;
 592             change_max = std::max(change_max, std::max(change, -change));
 593         }
 594         /* Limit the amount of scaling.
 595          * We need to use the same rescaling for all cells in one row,
 596          * otherwise the load balancing might not converge.
 597          */
 598         real sc = c_relax;
 599         if (change_max > change_limit)
 600         {
 601             sc *= change_limit/change_max;
 602         }
 603         for (int i = 0; i < ncd; i++)
 604         {
 605             /* Determine the relative imbalance of cell i */
 606             load_i         = comm->load[d].load[i*comm->load[d].nload+2];
 607             real imbalance = (load_i - load_aver)/(load_aver > 0 ? load_aver : 1);
 608             /* Determine the change of the cell size using underrelaxation */
 609             change       = -sc*imbalance;
 610             cell_size[i] = (rowMaster->cellFrac[i + 1] - rowMaster->cellFrac[i])*(1 + change);
 611         }
 612     }
 613
 614     real cellsize_limit_f  = cellsize_min_dlb(comm, d, dim)/ddbox->box_size[dim];
 615     cellsize_limit_f      *= DD_CELL_MARGIN;
 616     real dist_min_f_hard   = grid_jump_limit(comm, comm->cutoff, d)/ddbox->box_size[dim];
 617     real dist_min_f        = dist_min_f_hard * DD_CELL_MARGIN;
 618     if (ddbox->tric_dir[dim])
 619     {
 620         cellsize_limit_f /= ddbox->skew_fac[dim];
 621         dist_min_f       /= ddbox->skew_fac[dim];
 622     }
 623     if (bDynamicBox && d > 0)
 624     {
 625         dist_min_f *= DD_PRES_SCALE_MARGIN;
 626     }
 627     if (d > 0 && !bUniform)
 628     {
 629         /* Make sure that the grid is not shifted too much */
 630         for (int i = 1; i < ncd; i++)
 631         {
 632             const RowMaster::Bounds &boundsNeighbor = rowMaster->bounds[i - 1];
 633             RowMaster::Bounds       &bounds         = rowMaster->bounds[i];
 634
 635             if (bounds.cellFracUpperMin - boundsNeighbor.cellFracLowerMax < 2 * dist_min_f_hard)
 636             {
 637                 gmx_incons("Inconsistent DD boundary staggering limits!");
 638             }
 639             bounds.boundMin = boundsNeighbor.cellFracLowerMax + dist_min_f;
 640             real space       = rowMaster->cellFrac[i] - (boundsNeighbor.cellFracLowerMax + dist_min_f);
 641             if (space > 0)
 642             {
 643                 bounds.boundMin += 0.5*space;
 644             }
 645             bounds.boundMax  = bounds.cellFracUpperMin - dist_min_f;
 646             space            = rowMaster->cellFrac[i] - (bounds.cellFracUpperMin - dist_min_f);
 647             if (space < 0)
 648             {
 649                 rowMaster->bounds[i].boundMax += 0.5*space;
 650             }
 651             if (debug)
 652             {
 653                 fprintf(debug,
 654                         "dim %d boundary %d %.3f < %.3f < %.3f < %.3f < %.3f\n",
 655                         d, i,
 656                         boundsNeighbor.cellFracLowerMax + dist_min_f,
 657                         bounds.boundMin, rowMaster->cellFrac[i], bounds.boundMax,
 658                         bounds.cellFracUpperMin - dist_min_f);
 659             }
 660         }
 661     }
 662     range[1]                 = ncd;
 663     rowMaster->cellFrac[0]   = 0;
 664     rowMaster->cellFrac[ncd] = 1;
 665     dd_cell_sizes_dlb_root_enforce_limits(dd, d, dim, rowMaster, ddbox, bUniform, step, cellsize_limit_f, range);
 666
 667
 668     /* After the checks above, the cells should obey the cut-off
 669      * restrictions, but it does not hurt to check.
 670      */
 671     for (int i = 0; i < ncd; i++)
 672     {
 673         if (debug)
 674         {
 675             fprintf(debug, "Relative bounds dim %d  cell %d: %f %f\n",
 676                     dim, i, rowMaster->cellFrac[i], rowMaster->cellFrac[i + 1]);
 677         }
 678
 679         if ((bPBC || (i != 0 && i != dd->nc[dim]-1)) &&
 680             rowMaster->cellFrac[i + 1] - rowMaster->cellFrac[i] <
 681             cellsize_limit_f/DD_CELL_MARGIN)
 682         {
 683             char buf[22];
 684             fprintf(stderr,
 685                     "\nWARNING step %s: direction %c, cell %d too small: %f\n",
 686                     gmx_step_str(step, buf), dim2char(dim), i,
 687                     (rowMaster->cellFrac[i + 1] - rowMaster->cellFrac[i])
 688                     *ddbox->box_size[dim]*ddbox->skew_fac[dim]);
 689         }
 690     }
 691
 692     int pos = ncd + 1;
 693     /* Store the cell boundaries of the lower dimensions at the end */
 694     for (int d1 = 0; d1 < d; d1++)
 695     {
 696         rowMaster->cellFrac[pos++] = comm->cellsizesWithDlb[d1].fracLower;
 697         rowMaster->cellFrac[pos++] = comm->cellsizesWithDlb[d1].fracUpper;
 698     }
 699
 700     if (d < comm->npmedecompdim)
 701     {
 702         /* The master determines the maximum shift for
 703          * the coordinate communication between separate PME nodes.
 704          */
 705         set_pme_maxshift(dd, &comm->ddpme[d], bUniform, ddbox, rowMaster->cellFrac.data());
 706     }
 707     rowMaster->cellFrac[pos++] = comm->ddpme[0].maxshift;
 708     if (d >= 1)
 709     {
 710         rowMaster->cellFrac[pos++] = comm->ddpme[1].maxshift;
 711     }
 712 }
 713
 714 static void relative_to_absolute_cell_bounds(gmx_domdec_t      *dd,
 715                                              const gmx_ddbox_t *ddbox,
 716                                              int                dimind)
 717 {
 718     gmx_domdec_comm_t        *comm      = dd->comm;
 719     const DDCellsizesWithDlb &cellsizes = comm->cellsizesWithDlb[dimind];
 720
 721     /* Set the cell dimensions */
 722     int dim            = dd->dim[dimind];
 723     comm->cell_x0[dim] = cellsizes.fracLower*ddbox->box_size[dim];
 724     comm->cell_x1[dim] = cellsizes.fracUpper*ddbox->box_size[dim];
 725     if (dim >= ddbox->nboundeddim)
 726     {
 727         comm->cell_x0[dim] += ddbox->box0[dim];
 728         comm->cell_x1[dim] += ddbox->box0[dim];
 729     }
 730 }
 731
 732 static void distribute_dd_cell_sizes_dlb(gmx_domdec_t *dd,
 733                                          int d, int dim,
 734                                          gmx::ArrayRef<real> cellFracRow,
 735                                          const gmx_ddbox_t *ddbox)
 736 {
 737     gmx_domdec_comm_t &comm = *dd->comm;
 738
 739 #if GMX_MPI
 740     /* Each node would only need to know two fractions,
 741      * but it is probably cheaper to broadcast the whole array.
 742      */
 743     MPI_Bcast(cellFracRow.data(), ddCellFractionBufferSize(dd, d)*sizeof(real), MPI_BYTE,
 744               0, comm.mpi_comm_load[d]);
 745 #endif
 746     /* Copy the fractions for this dimension from the buffer */
 747     comm.cellsizesWithDlb[d].fracLower = cellFracRow[dd->ci[dim]    ];
 748     comm.cellsizesWithDlb[d].fracUpper = cellFracRow[dd->ci[dim] + 1];
 749     /* The whole array was communicated, so set the buffer position */
 750     int pos = dd->nc[dim] + 1;
 751     for (int d1 = 0; d1 <= d; d1++)
 752     {
 753         if (d1 < d)
 754         {
 755             /* Copy the cell fractions of the lower dimensions */
 756             comm.cellsizesWithDlb[d1].fracLower = cellFracRow[pos++];
 757             comm.cellsizesWithDlb[d1].fracUpper = cellFracRow[pos++];
 758         }
 759         relative_to_absolute_cell_bounds(dd, ddbox, d1);
 760     }
 761     /* Convert the communicated shift from float to int */
 762     comm.ddpme[0].maxshift = gmx::roundToInt(cellFracRow[pos++]);
 763     if (d >= 1)
 764     {
 765         comm.ddpme[1].maxshift = gmx::roundToInt(cellFracRow[pos++]);
 766     }
 767 }
 768
 769 static void set_dd_cell_sizes_dlb_change(gmx_domdec_t *dd,
 770                                          const gmx_ddbox_t *ddbox,
 771                                          gmx_bool bDynamicBox,
 772                                          gmx_bool bUniform, int64_t step)
 773 {
 774     for (int d = 0; d < dd->ndim; d++)
 775     {
 776         const int dim         = dd->dim[d];
 777         bool      isRowMember = true;
 778         bool      isRowRoot   = true;
 779         for (int d1 = d; d1 < dd->ndim; d1++)
 780         {
 781             if (dd->ci[dd->dim[d1]] > 0)
 782             {
 783                 if (d1 != d)
 784                 {
 785                     isRowMember = false;
 786                 }
 787                 isRowRoot = false;
 788             }
 789         }
 790         if (isRowMember)
 791         {
 792             DDCellsizesWithDlb  &cellsizes = dd->comm->cellsizesWithDlb[d];
 793             gmx::ArrayRef<real>  cellFracRow;
 794
 795             if (isRowRoot)
 796             {
 797                 RowMaster *rowMaster = cellsizes.rowMaster.get();
 798                 set_dd_cell_sizes_dlb_root(dd, d, dim, rowMaster,
 799                                            ddbox, bDynamicBox, bUniform, step);
 800                 cellFracRow = rowMaster->cellFrac;
 801             }
 802             else
 803             {
 804                 cellFracRow = cellsizes.fracRow;
 805             }
 806             distribute_dd_cell_sizes_dlb(dd, d, dim, cellFracRow, ddbox);
 807         }
 808     }
 809 }
 810
 811 static void set_dd_cell_sizes_dlb_nochange(gmx_domdec_t      *dd,
 812                                            const gmx_ddbox_t *ddbox)
 813 {
 814     int d;
 815
 816     /* This function assumes the box is static and should therefore
 817      * not be called when the box has changed since the last
 818      * call to dd_partition_system.
 819      */
 820     for (d = 0; d < dd->ndim; d++)
 821     {
 822         relative_to_absolute_cell_bounds(dd, ddbox, d);
 823     }
 824 }
 825
 826
 827
 828 static void set_dd_cell_sizes_dlb(gmx_domdec_t *dd,
 829                                   const gmx_ddbox_t *ddbox, gmx_bool bDynamicBox,
 830                                   gmx_bool bUniform, gmx_bool bDoDLB, int64_t step,
 831                                   gmx_wallcycle_t wcycle)
 832 {
 833     gmx_domdec_comm_t *comm;
 834     int                dim;
 835
 836     comm = dd->comm;
 837
 838     if (bDoDLB)
 839     {
 840         wallcycle_start(wcycle, ewcDDCOMMBOUND);
 841         set_dd_cell_sizes_dlb_change(dd, ddbox, bDynamicBox, bUniform, step);
 842         wallcycle_stop(wcycle, ewcDDCOMMBOUND);
 843     }
 844     else if (bDynamicBox)
 845     {
 846         set_dd_cell_sizes_dlb_nochange(dd, ddbox);
 847     }
 848
 849     /* Set the dimensions for which no DD is used */
 850     for (dim = 0; dim < DIM; dim++)
 851     {
 852         if (dd->nc[dim] == 1)
 853         {
 854             comm->cell_x0[dim] = 0;
 855             comm->cell_x1[dim] = ddbox->box_size[dim];
 856             if (dim >= ddbox->nboundeddim)
 857             {
 858                 comm->cell_x0[dim] += ddbox->box0[dim];
 859                 comm->cell_x1[dim] += ddbox->box0[dim];
 860             }
 861         }
 862     }
 863 }
 864
 865 void set_dd_cell_sizes(gmx_domdec_t *dd,
 866                        const gmx_ddbox_t *ddbox, gmx_bool bDynamicBox,
 867                        gmx_bool bUniform, gmx_bool bDoDLB, int64_t step,
 868                        gmx_wallcycle_t wcycle)
 869 {
 870     gmx_domdec_comm_t *comm = dd->comm;
 871
 872     /* Copy the old cell boundaries for the cg displacement check */
 873     copy_rvec(comm->cell_x0, comm->old_cell_x0);
 874     copy_rvec(comm->cell_x1, comm->old_cell_x1);
 875
 876     if (isDlbOn(comm))
 877     {
 878         if (DDMASTER(dd))
 879         {
 880             check_box_size(dd, ddbox);
 881         }
 882         set_dd_cell_sizes_dlb(dd, ddbox, bDynamicBox, bUniform, bDoDLB, step, wcycle);
 883     }
 884     else
 885     {
 886         ivec numPulses;
 887         set_dd_cell_sizes_slb(dd, ddbox, setcellsizeslbLOCAL, numPulses);
 888
 889         /* Check if the change in cell size requires a different number
 890          * of communication pulses and if so change the number.
 891          */
 892         for (int d = 0; d < dd->ndim; d++)
 893         {
 894             gmx_domdec_comm_dim_t &cd           = comm->cd[d];
 895             int                    numPulsesDim = numPulses[dd->dim[d]];
 896             if (cd.numPulses() != numPulsesDim)
 897             {
 898                 if (debug)
 899                 {
 900                     fprintf(debug, "Changing the number of halo communication pulses along dim %c from %d to %d\n",
 901                             dim2char(dd->dim[d]), cd.numPulses(), numPulsesDim);
 902                 }
 903                 cd.ind.resize(numPulsesDim);
 904             }
 905         }
 906     }
 907
 908     if (debug)
 909     {
 910         for (int d = 0; d < DIM; d++)
 911         {
 912             fprintf(debug, "cell_x[%d] %f - %f skew_fac %f\n",
 913                     d, comm->cell_x0[d], comm->cell_x1[d], ddbox->skew_fac[d]);
 914         }
 915     }
 916 }