Actual source code: sfgatherv.c
petsc-3.15.0 2021-03-30
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      2: #include <../src/vec/is/sf/impls/basic/gatherv/sfgatherv.h>

      4: /* Reuse the type. The difference is some fields (displs, recvcounts) are only significant
      5:    on rank 0 in Gatherv. On other ranks they are harmless NULL.
      6:  */
      7: typedef PetscSF_Allgatherv PetscSF_Gatherv;

      9: PETSC_INTERN PetscErrorCode PetscSFBcastBegin_Gatherv(PetscSF sf,MPI_Datatype unit,PetscMemType rootmtype,const void *rootdata,PetscMemType leafmtype,void *leafdata,MPI_Op op)
     10: {
     11:   PetscErrorCode       ierr;
     12:   PetscSFLink          link;
     13:   PetscMPIInt          sendcount;
     14:   MPI_Comm             comm;
     15:   PetscSF_Gatherv      *dat = (PetscSF_Gatherv*)sf->data;
     16:   void                 *rootbuf = NULL,*leafbuf = NULL; /* buffer seen by MPI */
     17:   MPI_Request          *req;

     20:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_BCAST,&link);
     21:   PetscSFLinkPackRootData(sf,link,PETSCSF_REMOTE,rootdata);
     22:   PetscSFLinkCopyRootBufferInCaseNotUseGpuAwareMPI(sf,link,PETSC_TRUE/* device2host before sending */);
     23:   PetscObjectGetComm((PetscObject)sf,&comm);
     24:   PetscMPIIntCast(sf->nroots,&sendcount);
     25:   PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_../../../../../..2LEAF,&rootbuf,&leafbuf,&req,NULL);
     26:   PetscSFLinkSyncStreamBeforeCallMPI(sf,link,PETSCSF_../../../../../..2LEAF);
     27:   MPIU_Igatherv(rootbuf,sendcount,unit,leafbuf,dat->recvcounts,dat->displs,unit,0/*rank 0*/,comm,req);
     28:   return(0);
     29: }

     31: static PetscErrorCode PetscSFReduceBegin_Gatherv(PetscSF sf,MPI_Datatype unit,PetscMemType leafmtype,const void *leafdata,PetscMemType rootmtype,void *rootdata,MPI_Op op)
     32: {
     33:   PetscErrorCode       ierr;
     34:   PetscSFLink          link;
     35:   PetscMPIInt          recvcount;
     36:   MPI_Comm             comm;
     37:   PetscSF_Gatherv      *dat = (PetscSF_Gatherv*)sf->data;
     38:   void                 *rootbuf = NULL,*leafbuf = NULL; /* buffer seen by MPI */
     39:   MPI_Request          *req;

     42:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_REDUCE,&link);
     43:   PetscSFLinkPackLeafData(sf,link,PETSCSF_REMOTE,leafdata);
     44:   PetscSFLinkCopyLeafBufferInCaseNotUseGpuAwareMPI(sf,link,PETSC_TRUE/* device2host before sending */);
     45:   PetscObjectGetComm((PetscObject)sf,&comm);
     46:   PetscMPIIntCast(sf->nroots,&recvcount);
     47:   PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_LEAF2../../../../../..,&rootbuf,&leafbuf,&req,NULL);
     48:   PetscSFLinkSyncStreamBeforeCallMPI(sf,link,PETSCSF_LEAF2../../../../../..);
     49:   MPIU_Iscatterv(leafbuf,dat->recvcounts,dat->displs,unit,rootbuf,recvcount,unit,0,comm,req);
     50:   return(0);
     51: }

     53: PETSC_INTERN PetscErrorCode PetscSFFetchAndOpBegin_Gatherv(PetscSF sf,MPI_Datatype unit,PetscMemType rootmtype,void *rootdata,PetscMemType leafmtype,const void *leafdata,void *leafupdate,MPI_Op op)
     54: {
     55:   PetscErrorCode      ierr;

     58:   /* In Gatherv, each root only has one leaf. So we just need to bcast rootdata to leafupdate and then reduce leafdata to rootdata */
     59:   PetscSFBcastBegin(sf,unit,rootdata,leafupdate,MPI_REPLACE);
     60:   PetscSFBcastEnd(sf,unit,rootdata,leafupdate,MPI_REPLACE);
     61:   PetscSFReduceBegin(sf,unit,leafdata,rootdata,op);
     62:   return(0);
     63: }

     65: PETSC_INTERN PetscErrorCode PetscSFCreate_Gatherv(PetscSF sf)
     66: {
     67:   PetscErrorCode  ierr;
     68:   PetscSF_Gatherv *dat = (PetscSF_Gatherv*)sf->data;

     71:   sf->ops->BcastEnd        = PetscSFBcastEnd_Basic;
     72:   sf->ops->ReduceEnd       = PetscSFReduceEnd_Basic;

     74:   /* Inherit from Allgatherv */
     75:   sf->ops->SetUp           = PetscSFSetUp_Allgatherv;
     76:   sf->ops->Reset           = PetscSFReset_Allgatherv;
     77:   sf->ops->Destroy         = PetscSFDestroy_Allgatherv;
     78:   sf->ops->GetGraph        = PetscSFGetGraph_Allgatherv;
     79:   sf->ops->GetLeafRanks    = PetscSFGetLeafRanks_Allgatherv;
     80:   sf->ops->GetRootRanks    = PetscSFGetRootRanks_Allgatherv;
     81:   sf->ops->FetchAndOpEnd   = PetscSFFetchAndOpEnd_Allgatherv;
     82:   sf->ops->CreateLocalSF   = PetscSFCreateLocalSF_Allgatherv;

     84:   /* Gatherv stuff */
     85:   sf->ops->BcastBegin      = PetscSFBcastBegin_Gatherv;
     86:   sf->ops->ReduceBegin     = PetscSFReduceBegin_Gatherv;
     87:   sf->ops->FetchAndOpBegin = PetscSFFetchAndOpBegin_Gatherv;

     89:   PetscNewLog(sf,&dat);
     90:   sf->data = (void*)dat;
     91:   return(0);
     92: }