xref: /petsc/src/vec/is/sf/impls/basic/gatherv/sfgatherv.c (revision 6a5217c03994f2d95bb2e6dbd8bed42381aeb015)
1 
2 #include <../src/vec/is/sf/impls/basic/gatherv/sfgatherv.h>
3 
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;
8 
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   PetscSFLink          link;
12   PetscMPIInt          sendcount;
13   MPI_Comm             comm;
14   PetscSF_Gatherv      *dat = (PetscSF_Gatherv*)sf->data;
15   void                 *rootbuf = NULL,*leafbuf = NULL; /* buffer seen by MPI */
16   MPI_Request          *req;
17 
18   PetscFunctionBegin;
19   PetscCall(PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_BCAST,&link));
20   PetscCall(PetscSFLinkPackRootData(sf,link,PETSCSF_REMOTE,rootdata));
21   PetscCall(PetscSFLinkCopyRootBufferInCaseNotUseGpuAwareMPI(sf,link,PETSC_TRUE/* device2host before sending */));
22   PetscCall(PetscObjectGetComm((PetscObject)sf,&comm));
23   PetscCall(PetscMPIIntCast(sf->nroots,&sendcount));
24   PetscCall(PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_ROOT2LEAF,&rootbuf,&leafbuf,&req,NULL));
25   PetscCall(PetscSFLinkSyncStreamBeforeCallMPI(sf,link,PETSCSF_ROOT2LEAF));
26   PetscCallMPI(MPIU_Igatherv(rootbuf,sendcount,unit,leafbuf,dat->recvcounts,dat->displs,unit,0/*rank 0*/,comm,req));
27   PetscFunctionReturn(0);
28 }
29 
30 static PetscErrorCode PetscSFReduceBegin_Gatherv(PetscSF sf,MPI_Datatype unit,PetscMemType leafmtype,const void *leafdata,PetscMemType rootmtype,void *rootdata,MPI_Op op)
31 {
32   PetscSFLink          link;
33   PetscMPIInt          recvcount;
34   MPI_Comm             comm;
35   PetscSF_Gatherv      *dat = (PetscSF_Gatherv*)sf->data;
36   void                 *rootbuf = NULL,*leafbuf = NULL; /* buffer seen by MPI */
37   MPI_Request          *req;
38 
39   PetscFunctionBegin;
40   PetscCall(PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_REDUCE,&link));
41   PetscCall(PetscSFLinkPackLeafData(sf,link,PETSCSF_REMOTE,leafdata));
42   PetscCall(PetscSFLinkCopyLeafBufferInCaseNotUseGpuAwareMPI(sf,link,PETSC_TRUE/* device2host before sending */));
43   PetscCall(PetscObjectGetComm((PetscObject)sf,&comm));
44   PetscCall(PetscMPIIntCast(sf->nroots,&recvcount));
45   PetscCall(PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_LEAF2ROOT,&rootbuf,&leafbuf,&req,NULL));
46   PetscCall(PetscSFLinkSyncStreamBeforeCallMPI(sf,link,PETSCSF_LEAF2ROOT));
47   PetscCallMPI(MPIU_Iscatterv(leafbuf,dat->recvcounts,dat->displs,unit,rootbuf,recvcount,unit,0,comm,req));
48   PetscFunctionReturn(0);
49 }
50 
51 PETSC_INTERN PetscErrorCode PetscSFFetchAndOpBegin_Gatherv(PetscSF sf,MPI_Datatype unit,PetscMemType rootmtype,void *rootdata,PetscMemType leafmtype,const void *leafdata,void *leafupdate,MPI_Op op)
52 {
53   PetscFunctionBegin;
54   /* In Gatherv, each root only has one leaf. So we just need to bcast rootdata to leafupdate and then reduce leafdata to rootdata */
55   PetscCall(PetscSFBcastBegin(sf,unit,rootdata,leafupdate,MPI_REPLACE));
56   PetscCall(PetscSFBcastEnd(sf,unit,rootdata,leafupdate,MPI_REPLACE));
57   PetscCall(PetscSFReduceBegin(sf,unit,leafdata,rootdata,op));
58   PetscFunctionReturn(0);
59 }
60 
61 PETSC_INTERN PetscErrorCode PetscSFCreate_Gatherv(PetscSF sf)
62 {
63   PetscSF_Gatherv *dat = (PetscSF_Gatherv*)sf->data;
64 
65   PetscFunctionBegin;
66   sf->ops->BcastEnd        = PetscSFBcastEnd_Basic;
67   sf->ops->ReduceEnd       = PetscSFReduceEnd_Basic;
68 
69   /* Inherit from Allgatherv */
70   sf->ops->SetUp           = PetscSFSetUp_Allgatherv;
71   sf->ops->Reset           = PetscSFReset_Allgatherv;
72   sf->ops->Destroy         = PetscSFDestroy_Allgatherv;
73   sf->ops->GetGraph        = PetscSFGetGraph_Allgatherv;
74   sf->ops->GetLeafRanks    = PetscSFGetLeafRanks_Allgatherv;
75   sf->ops->GetRootRanks    = PetscSFGetRootRanks_Allgatherv;
76   sf->ops->FetchAndOpEnd   = PetscSFFetchAndOpEnd_Allgatherv;
77   sf->ops->CreateLocalSF   = PetscSFCreateLocalSF_Allgatherv;
78 
79   /* Gatherv stuff */
80   sf->ops->BcastBegin      = PetscSFBcastBegin_Gatherv;
81   sf->ops->ReduceBegin     = PetscSFReduceBegin_Gatherv;
82   sf->ops->FetchAndOpBegin = PetscSFFetchAndOpBegin_Gatherv;
83 
84   PetscCall(PetscNewLog(sf,&dat));
85   sf->data = (void*)dat;
86   PetscFunctionReturn(0);
87 }
88