xref: /petsc/src/vec/is/sf/impls/basic/gatherv/sfgatherv.c (revision a69119a591a03a9d906b29c0a4e9802e4d7c9795)
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   PetscSFLink      link;
11   PetscMPIInt      sendcount;
12   MPI_Comm         comm;
13   PetscSF_Gatherv *dat     = (PetscSF_Gatherv *)sf->data;
14   void            *rootbuf = NULL, *leafbuf = NULL; /* buffer seen by MPI */
15   MPI_Request     *req;
16 
17   PetscFunctionBegin;
18   PetscCall(PetscSFLinkCreate(sf, unit, rootmtype, rootdata, leafmtype, leafdata, op, PETSCSF_BCAST, &link));
19   PetscCall(PetscSFLinkPackRootData(sf, link, PETSCSF_REMOTE, rootdata));
20   PetscCall(PetscSFLinkCopyRootBufferInCaseNotUseGpuAwareMPI(sf, link, PETSC_TRUE /* device2host before sending */));
21   PetscCall(PetscObjectGetComm((PetscObject)sf, &comm));
22   PetscCall(PetscMPIIntCast(sf->nroots, &sendcount));
23   PetscCall(PetscSFLinkGetMPIBuffersAndRequests(sf, link, PETSCSF_ROOT2LEAF, &rootbuf, &leafbuf, &req, NULL));
24   PetscCall(PetscSFLinkSyncStreamBeforeCallMPI(sf, link, PETSCSF_ROOT2LEAF));
25   PetscCallMPI(MPIU_Igatherv(rootbuf, sendcount, unit, leafbuf, dat->recvcounts, dat->displs, unit, 0 /*rank 0*/, comm, req));
26   PetscFunctionReturn(0);
27 }
28 
29 static PetscErrorCode PetscSFReduceBegin_Gatherv(PetscSF sf, MPI_Datatype unit, PetscMemType leafmtype, const void *leafdata, PetscMemType rootmtype, void *rootdata, MPI_Op op) {
30   PetscSFLink      link;
31   PetscMPIInt      recvcount;
32   MPI_Comm         comm;
33   PetscSF_Gatherv *dat     = (PetscSF_Gatherv *)sf->data;
34   void            *rootbuf = NULL, *leafbuf = NULL; /* buffer seen by MPI */
35   MPI_Request     *req;
36 
37   PetscFunctionBegin;
38   PetscCall(PetscSFLinkCreate(sf, unit, rootmtype, rootdata, leafmtype, leafdata, op, PETSCSF_REDUCE, &link));
39   PetscCall(PetscSFLinkPackLeafData(sf, link, PETSCSF_REMOTE, leafdata));
40   PetscCall(PetscSFLinkCopyLeafBufferInCaseNotUseGpuAwareMPI(sf, link, PETSC_TRUE /* device2host before sending */));
41   PetscCall(PetscObjectGetComm((PetscObject)sf, &comm));
42   PetscCall(PetscMPIIntCast(sf->nroots, &recvcount));
43   PetscCall(PetscSFLinkGetMPIBuffersAndRequests(sf, link, PETSCSF_LEAF2ROOT, &rootbuf, &leafbuf, &req, NULL));
44   PetscCall(PetscSFLinkSyncStreamBeforeCallMPI(sf, link, PETSCSF_LEAF2ROOT));
45   PetscCallMPI(MPIU_Iscatterv(leafbuf, dat->recvcounts, dat->displs, unit, rootbuf, recvcount, unit, 0, comm, req));
46   PetscFunctionReturn(0);
47 }
48 
49 PETSC_INTERN PetscErrorCode PetscSFFetchAndOpBegin_Gatherv(PetscSF sf, MPI_Datatype unit, PetscMemType rootmtype, void *rootdata, PetscMemType leafmtype, const void *leafdata, void *leafupdate, MPI_Op op) {
50   PetscFunctionBegin;
51   /* In Gatherv, each root only has one leaf. So we just need to bcast rootdata to leafupdate and then reduce leafdata to rootdata */
52   PetscCall(PetscSFBcastBegin(sf, unit, rootdata, leafupdate, MPI_REPLACE));
53   PetscCall(PetscSFBcastEnd(sf, unit, rootdata, leafupdate, MPI_REPLACE));
54   PetscCall(PetscSFReduceBegin(sf, unit, leafdata, rootdata, op));
55   PetscFunctionReturn(0);
56 }
57 
58 PETSC_INTERN PetscErrorCode PetscSFCreate_Gatherv(PetscSF sf) {
59   PetscSF_Gatherv *dat = (PetscSF_Gatherv *)sf->data;
60 
61   PetscFunctionBegin;
62   sf->ops->BcastEnd  = PetscSFBcastEnd_Basic;
63   sf->ops->ReduceEnd = PetscSFReduceEnd_Basic;
64 
65   /* Inherit from Allgatherv */
66   sf->ops->SetUp         = PetscSFSetUp_Allgatherv;
67   sf->ops->Reset         = PetscSFReset_Allgatherv;
68   sf->ops->Destroy       = PetscSFDestroy_Allgatherv;
69   sf->ops->GetGraph      = PetscSFGetGraph_Allgatherv;
70   sf->ops->GetLeafRanks  = PetscSFGetLeafRanks_Allgatherv;
71   sf->ops->GetRootRanks  = PetscSFGetRootRanks_Allgatherv;
72   sf->ops->FetchAndOpEnd = PetscSFFetchAndOpEnd_Allgatherv;
73   sf->ops->CreateLocalSF = PetscSFCreateLocalSF_Allgatherv;
74 
75   /* Gatherv stuff */
76   sf->ops->BcastBegin      = PetscSFBcastBegin_Gatherv;
77   sf->ops->ReduceBegin     = PetscSFReduceBegin_Gatherv;
78   sf->ops->FetchAndOpBegin = PetscSFFetchAndOpBegin_Gatherv;
79 
80   PetscCall(PetscNewLog(sf, &dat));
81   sf->data = (void *)dat;
82   PetscFunctionReturn(0);
83 }
84