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37 * \brief Implements the atom distribution constructor
39 * \author Berk Hess <hess@kth.se>
40 * \ingroup module_domdec
45 #include "atomdistribution.h"
47 #include "gromacs/math/vec.h"
49 #include "domdec_internal.h"
51 /*! \brief Returns the total number of rank, determined from the DD grid dimensions */
52 static int numRanks(const ivec numCells)
54 return numCells[XX] * numCells[YY] * numCells[ZZ];
57 AtomDistribution::AtomDistribution(const ivec numCells, int numAtomGroups, int numAtoms) :
58 domainGroups(numRanks(numCells)),
59 atomGroups(numAtomGroups),
60 intBuffer(2 * numRanks(numCells)),
61 rvecBuffer(numRanks(numCells) > c_maxNumRanksUseSendRecvForScatterAndGather ? numAtoms : 0)
63 for (int d = 0; d < DIM; d++)
65 cellSizesBuffer[d].resize(numCells[d] + 1);
69 void get_commbuffer_counts(AtomDistribution* ma, int** counts, int** disps)
71 GMX_ASSERT(ma != nullptr, "Need a valid AtomDistribution struct (on the master rank)");
73 /* Make the rvec count and displacement arrays */
74 int numRanks = ma->intBuffer.size() / 2;
75 *counts = ma->intBuffer.data();
76 *disps = ma->intBuffer.data() + numRanks;
77 for (int rank = 0; rank < numRanks; rank++)
79 (*counts)[rank] = ma->domainGroups[rank].numAtoms * sizeof(rvec);
80 (*disps)[rank] = (rank == 0 ? 0 : (*disps)[rank - 1] + (*counts)[rank - 1]);