Date: 2026-03-01T05:25:23+00:00

Actual source code: sfneighbor.c

      1: #include <../src/vec/is/sf/impls/basic/sfpack.h>
      2: #include <../src/vec/is/sf/impls/basic/sfbasic.h>
      3: #include <petscpkg_version.h>

      5: /* Convenience local types and wrappers */
      6: #if defined(PETSC_HAVE_MPI_LARGE_COUNT) && defined(PETSC_USE_64BIT_INDICES)
      7: typedef MPI_Count PetscSFCount;
      8: typedef MPI_Aint  PetscSFAint;
      9:   #define MPIU_Neighbor_alltoallv(a, b, c, d, e, f, g, h, i)            MPI_Neighbor_alltoallv_c(a, b, c, d, e, f, g, h, i)
     10:   #define MPIU_Neighbor_alltoallv_init(a, b, c, d, e, f, g, h, i, j, k) MPI_Neighbor_alltoallv_init_c(a, b, c, d, e, f, g, h, i, j, k)
     11:   #define MPIU_Ineighbor_alltoallv(a, b, c, d, e, f, g, h, i, j)        MPI_Ineighbor_alltoallv_c(a, b, c, d, e, f, g, h, i, j)
     12: #else
     13: typedef PetscMPIInt PetscSFCount;
     14: typedef PetscMPIInt PetscSFAint;
     15:   #define MPIU_Neighbor_alltoallv(a, b, c, d, e, f, g, h, i)            MPI_Neighbor_alltoallv(a, b, c, d, e, f, g, h, i)
     16:   #define MPIU_Neighbor_alltoallv_init(a, b, c, d, e, f, g, h, i, j, k) MPI_Neighbor_alltoallv_init(a, b, c, d, e, f, g, h, i, j, k)
     17:   #define MPIU_Ineighbor_alltoallv(a, b, c, d, e, f, g, h, i, j)        MPI_Ineighbor_alltoallv(a, b, c, d, e, f, g, h, i, j)
     18: #endif

     20: typedef struct {
     21:   SFBASICHEADER;
     22:   MPI_Comm      comms[2];                /* Communicators with distributed topology in both directions */
     23:   PetscBool     initialized[2];          /* Are the two communicators initialized? */
     24:   PetscSFCount *rootcounts, *leafcounts; /* counts for non-distinguished ranks */
     25:   PetscSFAint  *rootdispls, *leafdispls; /* displs for non-distinguished ranks */
     26:   PetscMPIInt  *rootweights, *leafweights;
     27:   PetscInt      rootdegree, leafdegree;
     28: } PetscSF_Neighbor;

     30: /*===================================================================================*/
     31: /*              Internal utility routines                                            */
     32: /*===================================================================================*/

     34: static inline PetscErrorCode PetscLogMPIMessages(PetscInt nsend, PetscSFCount *sendcnts, MPI_Datatype sendtype, PetscInt nrecv, PetscSFCount *recvcnts, MPI_Datatype recvtype)
     35: {
     36:   PetscFunctionBegin;
     37:   if (PetscDefined(USE_LOG)) {
     38:     petsc_isend_ct += (PetscLogDouble)nsend;
     39:     petsc_irecv_ct += (PetscLogDouble)nrecv;

     41:     if (sendtype != MPI_DATATYPE_NULL) {
     42:       PetscMPIInt i, typesize;
     43:       PetscCallMPI(MPI_Type_size(sendtype, &typesize));
     44:       for (i = 0; i < nsend; i++) petsc_isend_len += (PetscLogDouble)(sendcnts[i] * typesize);
     45:     }

     47:     if (recvtype != MPI_DATATYPE_NULL) {
     48:       PetscMPIInt i, typesize;
     49:       PetscCallMPI(MPI_Type_size(recvtype, &typesize));
     50:       for (i = 0; i < nrecv; i++) petsc_irecv_len += (PetscLogDouble)(recvcnts[i] * typesize);
     51:     }
     52:   }
     53:   PetscFunctionReturn(PETSC_SUCCESS);
     54: }

     56: /* Get the communicator with distributed graph topology, which is not cheap to build so we do it on demand (instead of at PetscSFSetUp time) */
     57: static PetscErrorCode PetscSFGetDistComm_Neighbor(PetscSF sf, PetscSFDirection direction, MPI_Comm *distcomm)
     58: {
     59:   PetscSF_Neighbor *dat = (PetscSF_Neighbor *)sf->data;

     61:   PetscFunctionBegin;
     62:   if (!dat->initialized[direction]) {
     63:     PetscMPIInt        nrootranks, ndrootranks, nleafranks, ndleafranks;
     64:     PetscMPIInt        indegree, outdegree;
     65:     const PetscMPIInt *rootranks, *leafranks, *sources, *destinations;
     66:     MPI_Comm           comm, *mycomm = &dat->comms[direction];

     68:     PetscCall(PetscSFGetRootInfo_Basic(sf, &nrootranks, &ndrootranks, &rootranks, NULL, NULL));       /* Which ranks will access my roots (I am a destination) */
     69:     PetscCall(PetscSFGetLeafInfo_Basic(sf, &nleafranks, &ndleafranks, &leafranks, NULL, NULL, NULL)); /* My leaves will access whose roots (I am a source) */
     70:     indegree     = nrootranks - ndrootranks;
     71:     outdegree    = nleafranks - ndleafranks;
     72:     sources      = PetscSafePointerPlusOffset(rootranks, ndrootranks);
     73:     destinations = PetscSafePointerPlusOffset(leafranks, ndleafranks);
     74:     PetscCall(PetscObjectGetComm((PetscObject)sf, &comm));
     75:     if (direction == PETSCSF_LEAF2ROOT) {
     76:       PetscCallMPI(MPI_Dist_graph_create_adjacent(comm, indegree, sources, dat->rootweights, outdegree, destinations, dat->leafweights, MPI_INFO_NULL, 1 /*reorder*/, mycomm));
     77:     } else { /* PETSCSF_ROOT2LEAF, reverse src & dest */
     78:       PetscCallMPI(MPI_Dist_graph_create_adjacent(comm, outdegree, destinations, dat->leafweights, indegree, sources, dat->rootweights, MPI_INFO_NULL, 1 /*reorder*/, mycomm));
     79:     }
     80:     dat->initialized[direction] = PETSC_TRUE;
     81:   }
     82:   *distcomm = dat->comms[direction];
     83:   PetscFunctionReturn(PETSC_SUCCESS);
     84: }

     86: // start MPI_Ineighbor_alltoallv (only used for inter-proccess communication)
     87: static PetscErrorCode PetscSFLinkStartCommunication_Neighbor(PetscSF sf, PetscSFLink link, PetscSFDirection direction)
     88: {
     89:   PetscSF_Neighbor *dat      = (PetscSF_Neighbor *)sf->data;
     90:   MPI_Comm          distcomm = MPI_COMM_NULL;
     91:   void             *rootbuf = NULL, *leafbuf = NULL;
     92:   MPI_Request      *req = NULL;

     94:   PetscFunctionBegin;
     95:   if (direction == PETSCSF_ROOT2LEAF) {
     96:     PetscCall(PetscSFLinkCopyRootBufferInCaseNotUseGpuAwareMPI(sf, link, PETSC_TRUE /* device2host before sending */));
     97:   } else {
     98:     PetscCall(PetscSFLinkCopyLeafBufferInCaseNotUseGpuAwareMPI(sf, link, PETSC_TRUE /* device2host */));
     99:   }

    101:   PetscCall(PetscSFGetDistComm_Neighbor(sf, direction, &distcomm));
    102:   PetscCall(PetscSFLinkGetMPIBuffersAndRequests(sf, link, direction, &rootbuf, &leafbuf, &req, NULL));
    103:   PetscCall(PetscSFLinkSyncStreamBeforeCallMPI(sf, link));

    105:   if (dat->rootdegree || dat->leafdegree) { // OpenMPI-3.0 ran into error with rootdegree = leafdegree = 0, so we skip the call in this case
    106:     if (direction == PETSCSF_ROOT2LEAF) {
    107:       PetscCallMPI(MPIU_Ineighbor_alltoallv(rootbuf, dat->rootcounts, dat->rootdispls, link->unit, leafbuf, dat->leafcounts, dat->leafdispls, link->unit, distcomm, req));
    108:       PetscCall(PetscLogMPIMessages(dat->rootdegree, dat->rootcounts, link->unit, dat->leafdegree, dat->leafcounts, link->unit));
    109:     } else {
    110:       PetscCallMPI(MPIU_Ineighbor_alltoallv(leafbuf, dat->leafcounts, dat->leafdispls, link->unit, rootbuf, dat->rootcounts, dat->rootdispls, link->unit, distcomm, req));
    111:       PetscCall(PetscLogMPIMessages(dat->leafdegree, dat->leafcounts, link->unit, dat->rootdegree, dat->rootcounts, link->unit));
    112:     }
    113:   }
    114:   PetscFunctionReturn(PETSC_SUCCESS);
    115: }

    117: #if defined(PETSC_HAVE_MPI_PERSISTENT_NEIGHBORHOOD_COLLECTIVES)
    118: static PetscErrorCode PetscSFLinkInitMPIRequests_Persistent_Neighbor(PetscSF sf, PetscSFLink link, PetscSFDirection direction)
    119: {
    120:   PetscSF_Neighbor  *dat           = (PetscSF_Neighbor *)sf->data;
    121:   MPI_Comm           distcomm      = MPI_COMM_NULL;
    122:   const PetscMemType rootmtype_mpi = link->rootmtype_mpi, leafmtype_mpi = link->leafmtype_mpi; /* Used to select buffers passed to MPI */
    123:   const PetscInt     rootdirect_mpi = link->rootdirect_mpi;
    124:   MPI_Request       *req            = link->rootreqs[direction][rootmtype_mpi][rootdirect_mpi];
    125:   void              *rootbuf = link->rootbuf[PETSCSF_REMOTE][rootmtype_mpi], *leafbuf = link->leafbuf[PETSCSF_REMOTE][leafmtype_mpi];
    126:   MPI_Info           info;

    128:   PetscFunctionBegin;
    129:   PetscCall(PetscSFGetDistComm_Neighbor(sf, direction, &distcomm));
    130:   if (dat->rootdegree || dat->leafdegree) {
    131:     if (!link->rootreqsinited[direction][rootmtype_mpi][rootdirect_mpi]) {
    132:       PetscCallMPI(MPI_Info_create(&info)); // currently, we don't use info
    133:       if (direction == PETSCSF_ROOT2LEAF) {
    134:         PetscCallMPI(MPIU_Neighbor_alltoallv_init(rootbuf, dat->rootcounts, dat->rootdispls, link->unit, leafbuf, dat->leafcounts, dat->leafdispls, link->unit, distcomm, info, req));
    135:       } else {
    136:         PetscCallMPI(MPIU_Neighbor_alltoallv_init(leafbuf, dat->leafcounts, dat->leafdispls, link->unit, rootbuf, dat->rootcounts, dat->rootdispls, link->unit, distcomm, info, req));
    137:       }
    138:       link->rootreqsinited[direction][rootmtype_mpi][rootdirect_mpi] = PETSC_TRUE;
    139:       PetscCallMPI(MPI_Info_free(&info));
    140:     }
    141:   }
    142:   PetscFunctionReturn(PETSC_SUCCESS);
    143: }

    145: // Start MPI requests. If use non-GPU aware MPI, we might need to copy data from device buf to host buf
    146: static PetscErrorCode PetscSFLinkStartCommunication_Persistent_Neighbor(PetscSF sf, PetscSFLink link, PetscSFDirection direction)
    147: {
    148:   PetscSF_Neighbor *dat = (PetscSF_Neighbor *)sf->data;
    149:   MPI_Request      *req = NULL;

    151:   PetscFunctionBegin;
    152:   if (direction == PETSCSF_ROOT2LEAF) {
    153:     PetscCall(PetscSFLinkCopyRootBufferInCaseNotUseGpuAwareMPI(sf, link, PETSC_TRUE /* device2host before sending */));
    154:   } else {
    155:     PetscCall(PetscSFLinkCopyLeafBufferInCaseNotUseGpuAwareMPI(sf, link, PETSC_TRUE /* device2host */));
    156:   }

    158:   PetscCall(PetscSFLinkGetMPIBuffersAndRequests(sf, link, direction, NULL, NULL, &req, NULL));
    159:   PetscCall(PetscSFLinkSyncStreamBeforeCallMPI(sf, link));
    160:   if (dat->rootdegree || dat->leafdegree) {
    161:     PetscCallMPI(MPI_Start(req));
    162:     if (direction == PETSCSF_ROOT2LEAF) {
    163:       PetscCall(PetscLogMPIMessages(dat->rootdegree, dat->rootcounts, link->unit, dat->leafdegree, dat->leafcounts, link->unit));
    164:     } else {
    165:       PetscCall(PetscLogMPIMessages(dat->leafdegree, dat->leafcounts, link->unit, dat->rootdegree, dat->rootcounts, link->unit));
    166:     }
    167:   }
    168:   PetscFunctionReturn(PETSC_SUCCESS);
    169: }
    170: #endif

    172: static PetscErrorCode PetscSFSetCommunicationOps_Neighbor(PetscSF sf, PetscSFLink link)
    173: {
    174:   PetscFunctionBegin;
    175: #if defined(PETSC_HAVE_MPI_PERSISTENT_NEIGHBORHOOD_COLLECTIVES)
    176:   if (sf->persistent) {
    177:     link->InitMPIRequests    = PetscSFLinkInitMPIRequests_Persistent_Neighbor;
    178:     link->StartCommunication = PetscSFLinkStartCommunication_Persistent_Neighbor;
    179:   } else
    180: #endif
    181:   {
    182:     link->StartCommunication = PetscSFLinkStartCommunication_Neighbor;
    183:   }
    184:   PetscFunctionReturn(PETSC_SUCCESS);
    185: }

    187: /*===================================================================================*/
    188: /*              Implementations of SF public APIs                                    */
    189: /*===================================================================================*/
    190: static PetscErrorCode PetscSFSetUp_Neighbor(PetscSF sf)
    191: {
    192:   PetscSF_Neighbor *dat = (PetscSF_Neighbor *)sf->data;
    193:   PetscMPIInt       nrootranks, ndrootranks, nleafranks, ndleafranks;
    194:   const PetscInt   *rootoffset, *leafoffset;
    195:   PetscMPIInt       m, n, m2, n2;

    197:   PetscFunctionBegin;
    198:   /* SFNeighbor inherits from Basic */
    199:   PetscCall(PetscSFSetUp_Basic(sf));
    200:   /* SFNeighbor specific */
    201:   PetscCall(PetscSFGetRootInfo_Basic(sf, &nrootranks, &ndrootranks, NULL, &rootoffset, NULL));
    202:   PetscCall(PetscSFGetLeafInfo_Basic(sf, &nleafranks, &ndleafranks, NULL, &leafoffset, NULL, NULL));
    203:   dat->rootdegree = m = (PetscMPIInt)(nrootranks - ndrootranks);
    204:   dat->leafdegree = n = (PetscMPIInt)(nleafranks - ndleafranks);
    205:   sf->nleafreqs       = 0;
    206:   dat->nrootreqs      = 1; // collectives only need one MPI_Request. We just put it in rootreqs[]

    208:   m2 = m;
    209:   n2 = n;
    210: #if defined(PETSC_HAVE_OPENMPI) // workaround for an OpenMPI 5.0.x bug, https://github.com/open-mpi/ompi/pull/12614
    211:   #if PETSC_PKG_OPENMPI_VERSION_LE(5, 0, 3)
    212:   m2 = m ? m : 1;
    213:   n2 = n ? n : 1;
    214:   #endif
    215: #endif
    216:   // Only setup MPI displs/counts for non-distinguished ranks. Distinguished ranks use shared memory
    217:   PetscCall(PetscMalloc6(m2, &dat->rootdispls, m2, &dat->rootcounts, m2, &dat->rootweights, n2, &dat->leafdispls, n2, &dat->leafcounts, n2, &dat->leafweights));

    219: #if defined(PETSC_HAVE_MPI_LARGE_COUNT) && defined(PETSC_USE_64BIT_INDICES)
    220:   for (PetscMPIInt i = ndrootranks, j = 0; i < nrootranks; i++, j++) {
    221:     dat->rootdispls[j]  = rootoffset[i] - rootoffset[ndrootranks];
    222:     dat->rootcounts[j]  = rootoffset[i + 1] - rootoffset[i];
    223:     dat->rootweights[j] = (PetscMPIInt)((PetscReal)dat->rootcounts[j] / (PetscReal)PETSC_INT_MAX * 2147483647); /* Scale to range of PetscMPIInt */
    224:   }

    226:   for (PetscMPIInt i = ndleafranks, j = 0; i < nleafranks; i++, j++) {
    227:     dat->leafdispls[j]  = leafoffset[i] - leafoffset[ndleafranks];
    228:     dat->leafcounts[j]  = leafoffset[i + 1] - leafoffset[i];
    229:     dat->leafweights[j] = (PetscMPIInt)((PetscReal)dat->leafcounts[j] / (PetscReal)PETSC_INT_MAX * 2147483647);
    230:   }
    231: #else
    232:   for (PetscMPIInt i = ndrootranks, j = 0; i < nrootranks; i++, j++) {
    233:     PetscCall(PetscMPIIntCast(rootoffset[i] - rootoffset[ndrootranks], &m));
    234:     dat->rootdispls[j] = m;
    235:     PetscCall(PetscMPIIntCast(rootoffset[i + 1] - rootoffset[i], &n));
    236:     dat->rootcounts[j]  = n;
    237:     dat->rootweights[j] = n;
    238:   }

    240:   for (PetscMPIInt i = ndleafranks, j = 0; i < nleafranks; i++, j++) {
    241:     PetscCall(PetscMPIIntCast(leafoffset[i] - leafoffset[ndleafranks], &m));
    242:     dat->leafdispls[j] = m;
    243:     PetscCall(PetscMPIIntCast(leafoffset[i + 1] - leafoffset[i], &n));
    244:     dat->leafcounts[j]  = n;
    245:     dat->leafweights[j] = n;
    246:   }
    247: #endif
    248:   PetscFunctionReturn(PETSC_SUCCESS);
    249: }

    251: static PetscErrorCode PetscSFReset_Neighbor(PetscSF sf)
    252: {
    253:   PetscSF_Neighbor *dat = (PetscSF_Neighbor *)sf->data;

    255:   PetscFunctionBegin;
    256:   PetscCheck(!dat->inuse, PetscObjectComm((PetscObject)sf), PETSC_ERR_ARG_WRONGSTATE, "Outstanding operation has not been completed");
    257:   PetscCall(PetscFree6(dat->rootdispls, dat->rootcounts, dat->rootweights, dat->leafdispls, dat->leafcounts, dat->leafweights));
    258:   for (int i = 0; i < 2; i++) {
    259:     if (dat->initialized[i]) {
    260:       PetscCallMPI(MPI_Comm_free(&dat->comms[i]));
    261:       dat->initialized[i] = PETSC_FALSE;
    262:     }
    263:   }
    264:   PetscCall(PetscSFReset_Basic(sf)); /* Common part */
    265:   PetscFunctionReturn(PETSC_SUCCESS);
    266: }

    268: static PetscErrorCode PetscSFDestroy_Neighbor(PetscSF sf)
    269: {
    270:   PetscFunctionBegin;
    271:   PetscCall(PetscSFReset_Neighbor(sf));
    272:   PetscCall(PetscFree(sf->data));
    273:   PetscFunctionReturn(PETSC_SUCCESS);
    274: }

    276: PETSC_INTERN PetscErrorCode PetscSFCreate_Neighbor(PetscSF sf)
    277: {
    278:   PetscSF_Neighbor *dat;

    280:   PetscFunctionBegin;
    281:   sf->ops->CreateEmbeddedRootSF = PetscSFCreateEmbeddedRootSF_Basic;
    282:   sf->ops->BcastBegin           = PetscSFBcastBegin_Basic;
    283:   sf->ops->BcastEnd             = PetscSFBcastEnd_Basic;
    284:   sf->ops->ReduceBegin          = PetscSFReduceBegin_Basic;
    285:   sf->ops->ReduceEnd            = PetscSFReduceEnd_Basic;
    286:   sf->ops->FetchAndOpBegin      = PetscSFFetchAndOpBegin_Basic;
    287:   sf->ops->FetchAndOpEnd        = PetscSFFetchAndOpEnd_Basic;
    288:   sf->ops->GetLeafRanks         = PetscSFGetLeafRanks_Basic;
    289:   sf->ops->View                 = PetscSFView_Basic;

    291:   sf->ops->SetUp               = PetscSFSetUp_Neighbor;
    292:   sf->ops->Reset               = PetscSFReset_Neighbor;
    293:   sf->ops->Destroy             = PetscSFDestroy_Neighbor;
    294:   sf->ops->SetCommunicationOps = PetscSFSetCommunicationOps_Neighbor;

    296: #if defined(PETSC_HAVE_MPI_PERSISTENT_NEIGHBORHOOD_COLLECTIVES)
    297:   PetscObjectOptionsBegin((PetscObject)sf);
    298:   PetscCall(PetscOptionsBool("-sf_neighbor_persistent", "Use MPI-4 persistent neighborhood collectives; used along with -sf_type neighbor", "PetscSFCreate", sf->persistent, &sf->persistent, NULL));
    299:   PetscOptionsEnd();
    300: #endif
    301:   sf->collective = PETSC_TRUE;

    303:   PetscCall(PetscNew(&dat));
    304:   sf->data = (void *)dat;
    305:   PetscFunctionReturn(PETSC_SUCCESS);
    306: }