Actual source code: sfallgatherv.c

  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 == 0 && !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 == 0 && 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: PETSC_INTERN PetscErrorCode PetscSFReduceEnd_Allgatherv(PetscSF sf,MPI_Datatype unit,const void *leafdata,void *rootdata,MPI_Op op)
150: {
151:   PetscErrorCode        ierr;
152:   PetscSFLink           link;

155:   if (op == MPI_REPLACE) {
156:     /* A rare case happens when op is MPI_REPLACE, using GPUs but no GPU aware MPI. In PetscSFReduceBegin_Allgather(v),
157:       we did a device to device copy and in effect finished the communication. But in PetscSFLinkFinishCommunication()
158:       of PetscSFReduceEnd_Basic(), it thinks since there is rootbuf, it calls PetscSFLinkCopyRootBufferInCaseNotUseGpuAwareMPI().
159:       It does a host to device memory copy on rootbuf, wrongly overwritting the results. So we don't overload
160:       PetscSFReduceEnd_Basic() in this case, and just reclaim the link.
161:      */
162:     PetscSFLinkGetInUse(sf,unit,rootdata,leafdata,PETSC_OWN_POINTER,&link);
163:     PetscSFLinkReclaim(sf,&link);
164:   } else {
165:     PetscSFReduceEnd_Basic(sf,unit,leafdata,rootdata,op);
166:   }
167:   return(0);
168: }

170: static PetscErrorCode PetscSFBcastToZero_Allgatherv(PetscSF sf,MPI_Datatype unit,PetscMemType rootmtype,const void *rootdata,PetscMemType leafmtype,void *leafdata)
171: {
172:   PetscErrorCode         ierr;
173:   PetscSFLink            link;
174:   PetscMPIInt            rank;

177:   PetscSFBcastBegin_Gatherv(sf,unit,rootmtype,rootdata,leafmtype,leafdata,MPI_REPLACE);
178:   PetscSFLinkGetInUse(sf,unit,rootdata,leafdata,PETSC_OWN_POINTER,&link);
179:   PetscSFLinkFinishCommunication(sf,link,PETSCSF_../../../../../..2LEAF);
180:   MPI_Comm_rank(PetscObjectComm((PetscObject)sf),&rank);
181:   if (rank == 0 && PetscMemTypeDevice(leafmtype) && !sf->use_gpu_aware_mpi) {
182:     (*link->Memcpy)(link,PETSC_MEMTYPE_DEVICE,leafdata,PETSC_MEMTYPE_HOST,link->leafbuf[PETSC_MEMTYPE_HOST],sf->leafbuflen[PETSCSF_REMOTE]*link->unitbytes);
183:   }
184:   PetscSFLinkReclaim(sf,&link);
185:   return(0);
186: }

188: /* 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).

190:    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
191:    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
192:    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
193:    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
194:    0,1,2 is 1,3,6 respectively. root is 10.

196:    We use a simpler implementation. From the same initial state, we copy leafdata to leafupdate
197:              rank-0   rank-1    rank-2
198:         Root     1
199:         Leaf     2       3         4
200:      Leafupdate  2       3         4

202:    Do MPI_Exscan on leafupdate,
203:              rank-0   rank-1    rank-2
204:         Root     1
205:         Leaf     2       3         4
206:      Leafupdate  2       2         5

208:    BcastAndOp from root to leafupdate,
209:              rank-0   rank-1    rank-2
210:         Root     1
211:         Leaf     2       3         4
212:      Leafupdate  3       3         6

214:    Copy root to leafupdate on rank-0
215:              rank-0   rank-1    rank-2
216:         Root     1
217:         Leaf     2       3         4
218:      Leafupdate  1       3         6

220:    Reduce from leaf to root,
221:              rank-0   rank-1    rank-2
222:         Root     10
223:         Leaf     2       3         4
224:      Leafupdate  1       3         6
225: */
226: PETSC_INTERN PetscErrorCode PetscSFFetchAndOpBegin_Allgatherv(PetscSF sf,MPI_Datatype unit,PetscMemType rootmtype,void *rootdata,PetscMemType leafmtype,const void *leafdata,void *leafupdate,MPI_Op op)
227: {
228:   PetscErrorCode         ierr;
229:   PetscSFLink            link;
230:   MPI_Comm               comm;
231:   PetscMPIInt            count;

234:   PetscObjectGetComm((PetscObject)sf,&comm);
235:   if (PetscMemTypeDevice(rootmtype) || PetscMemTypeDevice(leafmtype)) SETERRQ(comm,PETSC_ERR_SUP,"Do FetchAndOp on device");
236:   /* Copy leafdata to leafupdate */
237:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_FETCH,&link);
238:   PetscSFLinkPackLeafData(sf,link,PETSCSF_REMOTE,leafdata); /* Sync the device */
239:   (*link->Memcpy)(link,leafmtype,leafupdate,leafmtype,leafdata,sf->nleaves*link->unitbytes);
240:   PetscSFLinkGetInUse(sf,unit,rootdata,leafdata,PETSC_OWN_POINTER,&link);

242:   /* Exscan on leafupdate and then BcastAndOp rootdata to leafupdate */
243:   if (op == MPI_REPLACE) {
244:     PetscMPIInt size,rank,prev,next;
245:     MPI_Comm_rank(comm,&rank);
246:     MPI_Comm_size(comm,&size);
247:     prev = rank ?            rank-1 : MPI_PROC_NULL;
248:     next = (rank < size-1) ? rank+1 : MPI_PROC_NULL;
249:     PetscMPIIntCast(sf->nleaves,&count);
250:     MPI_Sendrecv_replace(leafupdate,count,unit,next,link->tag,prev,link->tag,comm,MPI_STATUSES_IGNORE);
251:   } else {
252:     PetscMPIIntCast(sf->nleaves*link->bs,&count);
253:     MPI_Exscan(MPI_IN_PLACE,leafupdate,count,link->basicunit,op,comm);
254:   }
255:   PetscSFLinkReclaim(sf,&link);
256:   PetscSFBcastBegin(sf,unit,rootdata,leafupdate,op);
257:   PetscSFBcastEnd(sf,unit,rootdata,leafupdate,op);

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

262:   /* Reduce leafdata to rootdata */
263:   PetscSFReduceBegin(sf,unit,leafdata,rootdata,op);
264:   return(0);
265: }

267: PETSC_INTERN PetscErrorCode PetscSFFetchAndOpEnd_Allgatherv(PetscSF sf,MPI_Datatype unit,void *rootdata,const void *leafdata,void *leafupdate,MPI_Op op)
268: {
269:   PetscErrorCode         ierr;

272:   PetscSFReduceEnd(sf,unit,leafdata,rootdata,op);
273:   return(0);
274: }

276: /* Get root ranks accessing my leaves */
277: PETSC_INTERN PetscErrorCode PetscSFGetRootRanks_Allgatherv(PetscSF sf,PetscInt *nranks,const PetscMPIInt **ranks,const PetscInt **roffset,const PetscInt **rmine,const PetscInt **rremote)
278: {
280:   PetscInt       i,j,k,size;
281:   const PetscInt *range;

284:   /* Lazily construct these large arrays if users really need them for this type of SF. Very likely, they do not */
285:   if (sf->nranks && !sf->ranks) { /* On rank!=0, sf->nranks=0. The sf->nranks test makes this routine also works for sfgatherv */
286:     size = sf->nranks;
287:     PetscLayoutGetRanges(sf->map,&range);
288:     PetscMalloc4(size,&sf->ranks,size+1,&sf->roffset,sf->nleaves,&sf->rmine,sf->nleaves,&sf->rremote);
289:     for (i=0; i<size; i++) sf->ranks[i] = i;
290:     PetscArraycpy(sf->roffset,range,size+1);
291:     for (i=0; i<sf->nleaves; i++) sf->rmine[i] = i; /*rmine are never NULL even for contiguous leaves */
292:     for (i=0; i<size; i++) {
293:       for (j=range[i],k=0; j<range[i+1]; j++,k++) sf->rremote[j] = k;
294:     }
295:   }

297:   if (nranks)  *nranks  = sf->nranks;
298:   if (ranks)   *ranks   = sf->ranks;
299:   if (roffset) *roffset = sf->roffset;
300:   if (rmine)   *rmine   = sf->rmine;
301:   if (rremote) *rremote = sf->rremote;
302:   return(0);
303: }

305: /* Get leaf ranks accessing my roots */
306: PETSC_INTERN PetscErrorCode PetscSFGetLeafRanks_Allgatherv(PetscSF sf,PetscInt *niranks,const PetscMPIInt **iranks,const PetscInt **ioffset,const PetscInt **irootloc)
307: {
308:   PetscErrorCode     ierr;
309:   PetscSF_Allgatherv *dat = (PetscSF_Allgatherv*)sf->data;
310:   MPI_Comm           comm;
311:   PetscMPIInt        size,rank;
312:   PetscInt           i,j;

315:   /* Lazily construct these large arrays if users really need them for this type of SF. Very likely, they do not */
316:   PetscObjectGetComm((PetscObject)sf,&comm);
317:   MPI_Comm_size(comm,&size);
318:   MPI_Comm_rank(comm,&rank);
319:   if (niranks) *niranks = size;

321:   /* PetscSF_Basic has distinguished incoming ranks. Here we do not need that. But we must put self as the first and
322:      sort other ranks. See comments in PetscSFSetUp_Basic about MatGetBrowsOfAoCols_MPIAIJ on why.
323:    */
324:   if (iranks) {
325:     if (!dat->iranks) {
326:       PetscMalloc1(size,&dat->iranks);
327:       dat->iranks[0] = rank;
328:       for (i=0,j=1; i<size; i++) {if (i == rank) continue; dat->iranks[j++] = i;}
329:     }
330:     *iranks = dat->iranks; /* dat->iranks was init'ed to NULL by PetscNewLog */
331:   }

333:   if (ioffset) {
334:     if (!dat->ioffset) {
335:       PetscMalloc1(size+1,&dat->ioffset);
336:       for (i=0; i<=size; i++) dat->ioffset[i] = i*sf->nroots;
337:     }
338:     *ioffset = dat->ioffset;
339:   }

341:   if (irootloc) {
342:     if (!dat->irootloc) {
343:       PetscMalloc1(sf->nleaves,&dat->irootloc);
344:       for (i=0; i<size; i++) {
345:         for (j=0; j<sf->nroots; j++) dat->irootloc[i*sf->nroots+j] = j;
346:       }
347:     }
348:     *irootloc = dat->irootloc;
349:   }
350:   return(0);
351: }

353: PETSC_INTERN PetscErrorCode PetscSFCreateLocalSF_Allgatherv(PetscSF sf,PetscSF *out)
354: {
355:   PetscInt       i,nroots,nleaves,rstart,*ilocal;
356:   PetscSFNode    *iremote;
357:   PetscSF        lsf;

361:   nleaves = sf->nleaves ? sf->nroots : 0; /* sf->nleaves can be zero with SFGather(v) */
362:   nroots  = nleaves;
363:   PetscMalloc1(nleaves,&ilocal);
364:   PetscMalloc1(nleaves,&iremote);
365:   PetscLayoutGetRange(sf->map,&rstart,NULL);

367:   for (i=0; i<nleaves; i++) {
368:     ilocal[i]        = rstart + i; /* lsf does not change leave indices */
369:     iremote[i].rank  = 0;          /* rank in PETSC_COMM_SELF */
370:     iremote[i].index = i;          /* root index */
371:   }

373:   PetscSFCreate(PETSC_COMM_SELF,&lsf);
374:   PetscSFSetGraph(lsf,nroots,nleaves,ilocal,PETSC_OWN_POINTER,iremote,PETSC_OWN_POINTER);
375:   PetscSFSetUp(lsf);
376:   *out = lsf;
377:   return(0);
378: }

380: PETSC_INTERN PetscErrorCode PetscSFCreate_Allgatherv(PetscSF sf)
381: {
382:   PetscErrorCode     ierr;
383:   PetscSF_Allgatherv *dat = (PetscSF_Allgatherv*)sf->data;

386:   sf->ops->BcastEnd        = PetscSFBcastEnd_Basic;
387:   sf->ops->ReduceEnd       = PetscSFReduceEnd_Allgatherv;

389:   sf->ops->SetUp           = PetscSFSetUp_Allgatherv;
390:   sf->ops->Reset           = PetscSFReset_Allgatherv;
391:   sf->ops->Destroy         = PetscSFDestroy_Allgatherv;
392:   sf->ops->GetRootRanks    = PetscSFGetRootRanks_Allgatherv;
393:   sf->ops->GetLeafRanks    = PetscSFGetLeafRanks_Allgatherv;
394:   sf->ops->GetGraph        = PetscSFGetGraph_Allgatherv;
395:   sf->ops->BcastBegin      = PetscSFBcastBegin_Allgatherv;
396:   sf->ops->ReduceBegin     = PetscSFReduceBegin_Allgatherv;
397:   sf->ops->FetchAndOpBegin = PetscSFFetchAndOpBegin_Allgatherv;
398:   sf->ops->FetchAndOpEnd   = PetscSFFetchAndOpEnd_Allgatherv;
399:   sf->ops->CreateLocalSF   = PetscSFCreateLocalSF_Allgatherv;
400:   sf->ops->BcastToZero     = PetscSFBcastToZero_Allgatherv;

402:   PetscNewLog(sf,&dat);
403:   sf->data = (void*)dat;
404:   return(0);
405: }