Actual source code: sfallgatherv.c

petsc-3.15.0 2021-04-05
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  1: #include <../src/vec/is/sf/impls/basic/allgatherv/sfallgatherv.h>

  3: PETSC_INTERN PetscErrorCode PetscSFBcastBegin_Gatherv(PetscSF,MPI_Datatype,PetscMemType,const void*,PetscMemType,void*,MPI_Op);

  5: /* PetscSFGetGraph is non-collective. An implementation should not have collective calls */
  6: PETSC_INTERN PetscErrorCode PetscSFGetGraph_Allgatherv(PetscSF sf,PetscInt *nroots,PetscInt *nleaves,const PetscInt **ilocal,const PetscSFNode **iremote)
  7: {
  9:   PetscInt       i,j,k;
 10:   const PetscInt *range;
 11:   PetscMPIInt    size;

 14:   MPI_Comm_size(PetscObjectComm((PetscObject)sf),&size);
 15:   if (nroots)  *nroots  = sf->nroots;
 16:   if (nleaves) *nleaves = sf->nleaves;
 17:   if (ilocal)  *ilocal  = NULL; /* Contiguous leaves */
 18:   if (iremote) {
 19:     if (!sf->remote && sf->nleaves) { /* The && sf->nleaves makes sfgatherv able to inherit this routine */
 20:       PetscLayoutGetRanges(sf->map,&range);
 21:       PetscMalloc1(sf->nleaves,&sf->remote);
 22:       sf->remote_alloc = sf->remote;
 23:       for (i=0; i<size; i++) {
 24:         for (j=range[i],k=0; j<range[i+1]; j++,k++) {
 25:           sf->remote[j].rank  = i;
 26:           sf->remote[j].index = k;
 27:         }
 28:       }
 29:     }
 30:     *iremote = sf->remote;
 31:   }
 32:   return(0);
 33: }

 35: PETSC_INTERN PetscErrorCode PetscSFSetUp_Allgatherv(PetscSF sf)
 36: {
 37:   PetscErrorCode     ierr;
 38:   PetscSF_Allgatherv *dat = (PetscSF_Allgatherv*)sf->data;
 39:   PetscMPIInt        size;
 40:   PetscInt           i;
 41:   const PetscInt     *range;

 44:   PetscSFSetUp_Allgather(sf);
 45:   MPI_Comm_size(PetscObjectComm((PetscObject)sf),&size);
 46:   if (sf->nleaves) { /* This if (sf->nleaves) test makes sfgatherv able to inherit this routine */
 47:     PetscMalloc1(size,&dat->recvcounts);
 48:     PetscMalloc1(size,&dat->displs);
 49:     PetscLayoutGetRanges(sf->map,&range);

 51:     for (i=0; i<size; i++) {
 52:       PetscMPIIntCast(range[i],&dat->displs[i]);
 53:       PetscMPIIntCast(range[i+1]-range[i],&dat->recvcounts[i]);
 54:     }
 55:   }
 56:   return(0);
 57: }

 59: PETSC_INTERN PetscErrorCode PetscSFReset_Allgatherv(PetscSF sf)
 60: {
 61:   PetscErrorCode         ierr;
 62:   PetscSF_Allgatherv     *dat = (PetscSF_Allgatherv*)sf->data;
 63:   PetscSFLink            link = dat->avail,next;

 66:   PetscFree(dat->iranks);
 67:   PetscFree(dat->ioffset);
 68:   PetscFree(dat->irootloc);
 69:   PetscFree(dat->recvcounts);
 70:   PetscFree(dat->displs);
 71:   if (dat->inuse) SETERRQ(PetscObjectComm((PetscObject)sf),PETSC_ERR_ARG_WRONGSTATE,"Outstanding operation has not been completed");
 72:   for (; link; link=next) {next = link->next; PetscSFLinkDestroy(sf,link);}
 73:   dat->avail = NULL;
 74:   return(0);
 75: }

 77: PETSC_INTERN PetscErrorCode PetscSFDestroy_Allgatherv(PetscSF sf)
 78: {

 82:   PetscSFReset_Allgatherv(sf);
 83:   PetscFree(sf->data);
 84:   return(0);
 85: }

 87: static PetscErrorCode PetscSFBcastBegin_Allgatherv(PetscSF sf,MPI_Datatype unit,PetscMemType rootmtype,const void *rootdata,PetscMemType leafmtype,void *leafdata,MPI_Op op)
 88: {
 89:   PetscErrorCode         ierr;
 90:   PetscSFLink            link;
 91:   PetscMPIInt            sendcount;
 92:   MPI_Comm               comm;
 93:   void                   *rootbuf = NULL,*leafbuf = NULL;
 94:   MPI_Request            *req;
 95:   PetscSF_Allgatherv     *dat = (PetscSF_Allgatherv*)sf->data;

 98:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_BCAST,&link);
 99:   PetscSFLinkPackRootData(sf,link,PETSCSF_REMOTE,rootdata);
100:   PetscSFLinkCopyRootBufferInCaseNotUseGpuAwareMPI(sf,link,PETSC_TRUE/* device2host before sending */);
101:   PetscObjectGetComm((PetscObject)sf,&comm);
102:   PetscMPIIntCast(sf->nroots,&sendcount);
103:   PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_../../../../../..2LEAF,&rootbuf,&leafbuf,&req,NULL);
104:   PetscSFLinkSyncStreamBeforeCallMPI(sf,link,PETSCSF_../../../../../..2LEAF);
105:   MPIU_Iallgatherv(rootbuf,sendcount,unit,leafbuf,dat->recvcounts,dat->displs,unit,comm,req);
106:   return(0);
107: }

109: static PetscErrorCode PetscSFReduceBegin_Allgatherv(PetscSF sf,MPI_Datatype unit,PetscMemType leafmtype,const void *leafdata,PetscMemType rootmtype,void *rootdata,MPI_Op op)
110: {
111:   PetscErrorCode         ierr;
112:   PetscSFLink            link;
113:   PetscSF_Allgatherv     *dat = (PetscSF_Allgatherv*)sf->data;
114:   PetscInt               rstart;
115:   PetscMPIInt            rank,count,recvcount;
116:   MPI_Comm               comm;
117:   void                   *rootbuf = NULL,*leafbuf = NULL;
118:   MPI_Request            *req;

121:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_REDUCE,&link);
122:   if (op == MPI_REPLACE) {
123:     /* REPLACE is only meaningful when all processes have the same leafdata to reduce. Therefore copying from local leafdata is fine */
124:     PetscLayoutGetRange(sf->map,&rstart,NULL);
125:     (*link->Memcpy)(link,rootmtype,rootdata,leafmtype,(const char*)leafdata+(size_t)rstart*link->unitbytes,(size_t)sf->nroots*link->unitbytes);
126:     if (PetscMemTypeDevice(leafmtype) && PetscMemTypeHost(rootmtype)) {(*link->SyncStream)(link);}
127:   } else {
128:     /* Reduce leafdata, then scatter to rootdata */
129:     PetscObjectGetComm((PetscObject)sf,&comm);
130:     MPI_Comm_rank(comm,&rank);
131:     PetscSFLinkPackLeafData(sf,link,PETSCSF_REMOTE,leafdata);
132:     PetscSFLinkCopyLeafBufferInCaseNotUseGpuAwareMPI(sf,link,PETSC_TRUE/* device2host before sending */);
133:     PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_LEAF2../../../../../..,&rootbuf,&leafbuf,&req,NULL);
134:     PetscMPIIntCast(dat->rootbuflen[PETSCSF_REMOTE],&recvcount);
135:     /* Allocate a separate leaf buffer on rank 0 */
136:     if (!rank && !link->leafbuf_alloc[PETSCSF_REMOTE][link->leafmtype_mpi]) {
137:       PetscSFMalloc(sf,link->leafmtype_mpi,sf->leafbuflen[PETSCSF_REMOTE]*link->unitbytes,(void**)&link->leafbuf_alloc[PETSCSF_REMOTE][link->leafmtype_mpi]);
138:     }
139:     /* In case we already copied leafdata from device to host (i.e., no use_gpu_aware_mpi), we need to adjust leafbuf on rank 0 */
140:     if (!rank && link->leafbuf_alloc[PETSCSF_REMOTE][link->leafmtype_mpi] == leafbuf) leafbuf = MPI_IN_PLACE;
141:     PetscMPIIntCast(sf->nleaves*link->bs,&count);
142:     PetscSFLinkSyncStreamBeforeCallMPI(sf,link,PETSCSF_LEAF2../../../../../..);
143:     MPI_Reduce(leafbuf,link->leafbuf_alloc[PETSCSF_REMOTE][link->leafmtype_mpi],count,link->basicunit,op,0,comm); /* Must do reduce with MPI builltin datatype basicunit */
144:     MPIU_Iscatterv(link->leafbuf_alloc[PETSCSF_REMOTE][link->leafmtype_mpi],dat->recvcounts,dat->displs,unit,rootbuf,recvcount,unit,0,comm,req);
145:   }
146:   return(0);
147: }

149: static PetscErrorCode PetscSFBcastToZero_Allgatherv(PetscSF sf,MPI_Datatype unit,PetscMemType rootmtype,const void *rootdata,PetscMemType leafmtype,void *leafdata)
150: {
151:   PetscErrorCode         ierr;
152:   PetscSFLink            link;
153:   PetscMPIInt            rank;

156:   PetscSFBcastBegin_Gatherv(sf,unit,rootmtype,rootdata,leafmtype,leafdata,MPI_REPLACE);
157:   PetscSFLinkGetInUse(sf,unit,rootdata,leafdata,PETSC_OWN_POINTER,&link);
158:   PetscSFLinkFinishCommunication(sf,link,PETSCSF_../../../../../..2LEAF);
159:   MPI_Comm_rank(PetscObjectComm((PetscObject)sf),&rank);
160:   if (!rank && PetscMemTypeDevice(leafmtype) && !sf->use_gpu_aware_mpi) {
161:     (*link->Memcpy)(link,PETSC_MEMTYPE_DEVICE,leafdata,PETSC_MEMTYPE_HOST,link->leafbuf[PETSC_MEMTYPE_HOST],sf->leafbuflen[PETSCSF_REMOTE]*link->unitbytes);
162:   }
163:   PetscSFLinkReclaim(sf,&link);
164:   return(0);
165: }

167: /* This routine is very tricky (I believe it is rarely used with this kind of graph so just provide a simple but not-optimal implementation).

169:    Suppose we have three ranks. Rank 0 has a root with value 1. Rank 0,1,2 has a leaf with value 2,3,4 respectively. The leaves are connected
170:    to the root on rank 0. Suppose op=MPI_SUM and rank 0,1,2 gets root state in their rank order. By definition of this routine, rank 0 sees 1
171:    in root, fetches it into its leafupate, then updates root to 1 + 2 = 3; rank 1 sees 3 in root, fetches it into its leafupate, then updates
172:    root to 3 + 3 = 6; rank 2 sees 6 in root, fetches it into its leafupdate, then updates root to 6 + 4 = 10.  At the end, leafupdate on rank
173:    0,1,2 is 1,3,6 respectively. root is 10.

175:    We use a simpler implementation. From the same initial state, we copy leafdata to leafupdate
176:              rank-0   rank-1    rank-2
177:         Root     1
178:         Leaf     2       3         4
179:      Leafupdate  2       3         4

181:    Do MPI_Exscan on leafupdate,
182:              rank-0   rank-1    rank-2
183:         Root     1
184:         Leaf     2       3         4
185:      Leafupdate  2       2         5

187:    BcastAndOp from root to leafupdate,
188:              rank-0   rank-1    rank-2
189:         Root     1
190:         Leaf     2       3         4
191:      Leafupdate  3       3         6

193:    Copy root to leafupdate on rank-0
194:              rank-0   rank-1    rank-2
195:         Root     1
196:         Leaf     2       3         4
197:      Leafupdate  1       3         6

199:    Reduce from leaf to root,
200:              rank-0   rank-1    rank-2
201:         Root     10
202:         Leaf     2       3         4
203:      Leafupdate  1       3         6
204: */
205: PETSC_INTERN PetscErrorCode PetscSFFetchAndOpBegin_Allgatherv(PetscSF sf,MPI_Datatype unit,PetscMemType rootmtype,void *rootdata,PetscMemType leafmtype,const void *leafdata,void *leafupdate,MPI_Op op)
206: {
207:   PetscErrorCode         ierr;
208:   PetscSFLink            link;
209:   MPI_Comm               comm;
210:   PetscMPIInt            count;

213:   PetscObjectGetComm((PetscObject)sf,&comm);
214:   if (PetscMemTypeDevice(rootmtype) || PetscMemTypeDevice(leafmtype)) SETERRQ(comm,PETSC_ERR_SUP,"Do FetchAndOp on device");
215:   /* Copy leafdata to leafupdate */
216:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_FETCH,&link);
217:   PetscSFLinkPackLeafData(sf,link,PETSCSF_REMOTE,leafdata); /* Sync the device */
218:   (*link->Memcpy)(link,leafmtype,leafupdate,leafmtype,leafdata,sf->nleaves*link->unitbytes);
219:   PetscSFLinkGetInUse(sf,unit,rootdata,leafdata,PETSC_OWN_POINTER,&link);

221:   /* Exscan on leafupdate and then BcastAndOp rootdata to leafupdate */
222:   if (op == MPI_REPLACE) {
223:     PetscMPIInt size,rank,prev,next;
224:     MPI_Comm_rank(comm,&rank);
225:     MPI_Comm_size(comm,&size);
226:     prev = rank ?            rank-1 : MPI_PROC_NULL;
227:     next = (rank < size-1) ? rank+1 : MPI_PROC_NULL;
228:     PetscMPIIntCast(sf->nleaves,&count);
229:     MPI_Sendrecv_replace(leafupdate,count,unit,next,link->tag,prev,link->tag,comm,MPI_STATUSES_IGNORE);
230:   } else {
231:     PetscMPIIntCast(sf->nleaves*link->bs,&count);
232:     MPI_Exscan(MPI_IN_PLACE,leafupdate,count,link->basicunit,op,comm);
233:   }
234:   PetscSFLinkReclaim(sf,&link);
235:   PetscSFBcastBegin(sf,unit,rootdata,leafupdate,op);
236:   PetscSFBcastEnd(sf,unit,rootdata,leafupdate,op);

238:   /* Bcast roots to rank 0's leafupdate */
239:   PetscSFBcastToZero_Private(sf,unit,rootdata,leafupdate); /* Using this line makes Allgather SFs able to inherit this routine */

241:   /* Reduce leafdata to rootdata */
242:   PetscSFReduceBegin(sf,unit,leafdata,rootdata,op);
243:   return(0);
244: }

246: PETSC_INTERN PetscErrorCode PetscSFFetchAndOpEnd_Allgatherv(PetscSF sf,MPI_Datatype unit,void *rootdata,const void *leafdata,void *leafupdate,MPI_Op op)
247: {
248:   PetscErrorCode         ierr;

251:   PetscSFReduceEnd(sf,unit,leafdata,rootdata,op);
252:   return(0);
253: }

255: /* Get root ranks accessing my leaves */
256: PETSC_INTERN PetscErrorCode PetscSFGetRootRanks_Allgatherv(PetscSF sf,PetscInt *nranks,const PetscMPIInt **ranks,const PetscInt **roffset,const PetscInt **rmine,const PetscInt **rremote)
257: {
259:   PetscInt       i,j,k,size;
260:   const PetscInt *range;

263:   /* Lazily construct these large arrays if users really need them for this type of SF. Very likely, they do not */
264:   if (sf->nranks && !sf->ranks) { /* On rank!=0, sf->nranks=0. The sf->nranks test makes this routine also works for sfgatherv */
265:     size = sf->nranks;
266:     PetscLayoutGetRanges(sf->map,&range);
267:     PetscMalloc4(size,&sf->ranks,size+1,&sf->roffset,sf->nleaves,&sf->rmine,sf->nleaves,&sf->rremote);
268:     for (i=0; i<size; i++) sf->ranks[i] = i;
269:     PetscArraycpy(sf->roffset,range,size+1);
270:     for (i=0; i<sf->nleaves; i++) sf->rmine[i] = i; /*rmine are never NULL even for contiguous leaves */
271:     for (i=0; i<size; i++) {
272:       for (j=range[i],k=0; j<range[i+1]; j++,k++) sf->rremote[j] = k;
273:     }
274:   }

276:   if (nranks)  *nranks  = sf->nranks;
277:   if (ranks)   *ranks   = sf->ranks;
278:   if (roffset) *roffset = sf->roffset;
279:   if (rmine)   *rmine   = sf->rmine;
280:   if (rremote) *rremote = sf->rremote;
281:   return(0);
282: }

284: /* Get leaf ranks accessing my roots */
285: PETSC_INTERN PetscErrorCode PetscSFGetLeafRanks_Allgatherv(PetscSF sf,PetscInt *niranks,const PetscMPIInt **iranks,const PetscInt **ioffset,const PetscInt **irootloc)
286: {
287:   PetscErrorCode     ierr;
288:   PetscSF_Allgatherv *dat = (PetscSF_Allgatherv*)sf->data;
289:   MPI_Comm           comm;
290:   PetscMPIInt        size,rank;
291:   PetscInt           i,j;

294:   /* Lazily construct these large arrays if users really need them for this type of SF. Very likely, they do not */
295:   PetscObjectGetComm((PetscObject)sf,&comm);
296:   MPI_Comm_size(comm,&size);
297:   MPI_Comm_rank(comm,&rank);
298:   if (niranks) *niranks = size;

300:   /* PetscSF_Basic has distinguished incoming ranks. Here we do not need that. But we must put self as the first and
301:      sort other ranks. See comments in PetscSFSetUp_Basic about MatGetBrowsOfAoCols_MPIAIJ on why.
302:    */
303:   if (iranks) {
304:     if (!dat->iranks) {
305:       PetscMalloc1(size,&dat->iranks);
306:       dat->iranks[0] = rank;
307:       for (i=0,j=1; i<size; i++) {if (i == rank) continue; dat->iranks[j++] = i;}
308:     }
309:     *iranks = dat->iranks; /* dat->iranks was init'ed to NULL by PetscNewLog */
310:   }

312:   if (ioffset) {
313:     if (!dat->ioffset) {
314:       PetscMalloc1(size+1,&dat->ioffset);
315:       for (i=0; i<=size; i++) dat->ioffset[i] = i*sf->nroots;
316:     }
317:     *ioffset = dat->ioffset;
318:   }

320:   if (irootloc) {
321:     if (!dat->irootloc) {
322:       PetscMalloc1(sf->nleaves,&dat->irootloc);
323:       for (i=0; i<size; i++) {
324:         for (j=0; j<sf->nroots; j++) dat->irootloc[i*sf->nroots+j] = j;
325:       }
326:     }
327:     *irootloc = dat->irootloc;
328:   }
329:   return(0);
330: }

332: PETSC_INTERN PetscErrorCode PetscSFCreateLocalSF_Allgatherv(PetscSF sf,PetscSF *out)
333: {
334:   PetscInt       i,nroots,nleaves,rstart,*ilocal;
335:   PetscSFNode    *iremote;
336:   PetscSF        lsf;

340:   nleaves = sf->nleaves ? sf->nroots : 0; /* sf->nleaves can be zero with SFGather(v) */
341:   nroots  = nleaves;
342:   PetscMalloc1(nleaves,&ilocal);
343:   PetscMalloc1(nleaves,&iremote);
344:   PetscLayoutGetRange(sf->map,&rstart,NULL);

346:   for (i=0; i<nleaves; i++) {
347:     ilocal[i]        = rstart + i; /* lsf does not change leave indices */
348:     iremote[i].rank  = 0;          /* rank in PETSC_COMM_SELF */
349:     iremote[i].index = i;          /* root index */
350:   }

352:   PetscSFCreate(PETSC_COMM_SELF,&lsf);
353:   PetscSFSetGraph(lsf,nroots,nleaves,ilocal,PETSC_OWN_POINTER,iremote,PETSC_OWN_POINTER);
354:   PetscSFSetUp(lsf);
355:   *out = lsf;
356:   return(0);
357: }

359: PETSC_INTERN PetscErrorCode PetscSFCreate_Allgatherv(PetscSF sf)
360: {
361:   PetscErrorCode     ierr;
362:   PetscSF_Allgatherv *dat = (PetscSF_Allgatherv*)sf->data;

365:   sf->ops->BcastEnd        = PetscSFBcastEnd_Basic;
366:   sf->ops->ReduceEnd       = PetscSFReduceEnd_Basic;

368:   sf->ops->SetUp           = PetscSFSetUp_Allgatherv;
369:   sf->ops->Reset           = PetscSFReset_Allgatherv;
370:   sf->ops->Destroy         = PetscSFDestroy_Allgatherv;
371:   sf->ops->GetRootRanks    = PetscSFGetRootRanks_Allgatherv;
372:   sf->ops->GetLeafRanks    = PetscSFGetLeafRanks_Allgatherv;
373:   sf->ops->GetGraph        = PetscSFGetGraph_Allgatherv;
374:   sf->ops->BcastBegin      = PetscSFBcastBegin_Allgatherv;
375:   sf->ops->ReduceBegin     = PetscSFReduceBegin_Allgatherv;
376:   sf->ops->FetchAndOpBegin = PetscSFFetchAndOpBegin_Allgatherv;
377:   sf->ops->FetchAndOpEnd   = PetscSFFetchAndOpEnd_Allgatherv;
378:   sf->ops->CreateLocalSF   = PetscSFCreateLocalSF_Allgatherv;
379:   sf->ops->BcastToZero     = PetscSFBcastToZero_Allgatherv;

381:   PetscNewLog(sf,&dat);
382:   sf->data = (void*)dat;
383:   return(0);
384: }