Date: 2016-07-24T16:51:09+00:00

Actual source code: aomemscalable.c
petsc-3.7.3 2016-07-24
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      2: /*
      3:     The memory scalable AO application ordering routines. These store the
      4:   local orderings on each processor.
      5: */

      7: #include <../src/vec/is/ao/aoimpl.h>          /*I  "petscao.h"   I*/

      9: typedef struct {
     10:   PetscInt    *app_loc;    /* app_loc[i] is the partner for the ith local PETSc slot */
     11:   PetscInt    *petsc_loc;  /* petsc_loc[j] is the partner for the jth local app slot */
     12:   PetscLayout map;         /* determines the local sizes of ao */
     13: } AO_MemoryScalable;

     15: /*
     16:        All processors have the same data so processor 1 prints it
     17: */
     20: PetscErrorCode AOView_MemoryScalable(AO ao,PetscViewer viewer)
     21: {
     22:   PetscErrorCode    ierr;
     23:   PetscMPIInt       rank,size;
     24:   AO_MemoryScalable *aomems = (AO_MemoryScalable*)ao->data;
     25:   PetscBool         iascii;
     26:   PetscMPIInt       tag_app,tag_petsc;
     27:   PetscLayout       map = aomems->map;
     28:   PetscInt          *app,*app_loc,*petsc,*petsc_loc,len,i,j;
     29:   MPI_Status        status;

     32:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
     33:   if (!iascii) SETERRQ1(PetscObjectComm((PetscObject)viewer),PETSC_ERR_SUP,"Viewer type %s not supported for AO MemoryScalable",((PetscObject)viewer)->type_name);

     35:   MPI_Comm_rank(PetscObjectComm((PetscObject)ao),&rank);
     36:   MPI_Comm_size(PetscObjectComm((PetscObject)ao),&size);

     38:   PetscObjectGetNewTag((PetscObject)ao,&tag_app);
     39:   PetscObjectGetNewTag((PetscObject)ao,&tag_petsc);

     41:   if (!rank) {
     42:     PetscViewerASCIIPrintf(viewer,"Number of elements in ordering %D\n",ao->N);
     43:     PetscViewerASCIIPrintf(viewer,  "PETSc->App  App->PETSc\n");

     45:     PetscMalloc2(map->N,&app,map->N,&petsc);
     46:     len  = map->n;
     47:     /* print local AO */
     48:     PetscViewerASCIIPrintf(viewer,"Process [%D]\n",rank);
     49:     for (i=0; i<len; i++) {
     50:       PetscViewerASCIIPrintf(viewer,"%3D  %3D    %3D  %3D\n",i,aomems->app_loc[i],i,aomems->petsc_loc[i]);
     51:     }

     53:     /* recv and print off-processor's AO */
     54:     for (i=1; i<size; i++) {
     55:       len       = map->range[i+1] - map->range[i];
     56:       app_loc   = app  + map->range[i];
     57:       petsc_loc = petsc+ map->range[i];
     58:       MPI_Recv(app_loc,(PetscMPIInt)len,MPIU_INT,i,tag_app,PetscObjectComm((PetscObject)ao),&status);
     59:       MPI_Recv(petsc_loc,(PetscMPIInt)len,MPIU_INT,i,tag_petsc,PetscObjectComm((PetscObject)ao),&status);
     60:       PetscViewerASCIIPrintf(viewer,"Process [%D]\n",i);
     61:       for (j=0; j<len; j++) {
     62:         PetscViewerASCIIPrintf(viewer,"%3D  %3D    %3D  %3D\n",map->range[i]+j,app_loc[j],map->range[i]+j,petsc_loc[j]);
     63:       }
     64:     }
     65:     PetscFree2(app,petsc);

     67:   } else {
     68:     /* send values */
     69:     MPI_Send((void*)aomems->app_loc,map->n,MPIU_INT,0,tag_app,PetscObjectComm((PetscObject)ao));
     70:     MPI_Send((void*)aomems->petsc_loc,map->n,MPIU_INT,0,tag_petsc,PetscObjectComm((PetscObject)ao));
     71:   }
     72:   PetscViewerFlush(viewer);
     73:   return(0);
     74: }

     78: PetscErrorCode AODestroy_MemoryScalable(AO ao)
     79: {
     80:   AO_MemoryScalable *aomems = (AO_MemoryScalable*)ao->data;
     81:   PetscErrorCode    ierr;

     84:   PetscFree2(aomems->app_loc,aomems->petsc_loc);
     85:   PetscLayoutDestroy(&aomems->map);
     86:   PetscFree(aomems);
     87:   return(0);
     88: }

     90: /*
     91:    Input Parameters:
     92: +   ao - the application ordering context
     93: .   n  - the number of integers in ia[]
     94: .   ia - the integers; these are replaced with their mapped value
     95: -   maploc - app_loc or petsc_loc in struct "AO_MemoryScalable"

     97:    Output Parameter:
     98: .   ia - the mapped interges
     99:  */
    102: PetscErrorCode AOMap_MemoryScalable_private(AO ao,PetscInt n,PetscInt *ia,PetscInt *maploc)
    103: {
    104:   PetscErrorCode    ierr;
    105:   AO_MemoryScalable *aomems = (AO_MemoryScalable*)ao->data;
    106:   MPI_Comm          comm;
    107:   PetscMPIInt       rank,size,tag1,tag2;
    108:   PetscInt          *owner,*start,*sizes,nsends,nreceives;
    109:   PetscInt          nmax,count,*sindices,*rindices,i,j,idx,lastidx,*sindices2,*rindices2;
    110:   PetscInt          *owners = aomems->map->range;
    111:   MPI_Request       *send_waits,*recv_waits,*send_waits2,*recv_waits2;
    112:   MPI_Status        recv_status;
    113:   PetscMPIInt       nindices,source,widx;
    114:   PetscInt          *rbuf,*sbuf;
    115:   MPI_Status        *send_status,*send_status2;

    118:   PetscObjectGetComm((PetscObject)ao,&comm);
    119:   MPI_Comm_rank(comm,&rank);
    120:   MPI_Comm_size(comm,&size);

    122:   /*  first count number of contributors to each processor */
    123:   PetscMalloc2(2*size,&sizes,size,&start);
    124:   PetscMemzero(sizes,2*size*sizeof(PetscInt));
    125:   PetscCalloc1(n,&owner);

    127:   j       = 0;
    128:   lastidx = -1;
    129:   for (i=0; i<n; i++) {
    130:     /* if indices are NOT locally sorted, need to start search at the beginning */
    131:     if (lastidx > (idx = ia[i])) j = 0;
    132:     lastidx = idx;
    133:     for (; j<size; j++) {
    134:       if (idx >= owners[j] && idx < owners[j+1]) {
    135:         sizes[2*j]++;     /* num of indices to be sent */
    136:         sizes[2*j+1] = 1; /* send to proc[j] */
    137:         owner[i]      = j;
    138:         break;
    139:       }
    140:     }
    141:   }
    142:   sizes[2*rank]=sizes[2*rank+1]=0; /* do not receive from self! */
    143:   nsends        = 0;
    144:   for (i=0; i<size; i++) nsends += sizes[2*i+1];

    146:   /* inform other processors of number of messages and max length*/
    147:   PetscMaxSum(comm,sizes,&nmax,&nreceives);

    149:   /* allocate arrays */
    150:   PetscObjectGetNewTag((PetscObject)ao,&tag1);
    151:   PetscObjectGetNewTag((PetscObject)ao,&tag2);

    153:   PetscMalloc2(nreceives*nmax,&rindices,nreceives,&recv_waits);
    154:   PetscMalloc2(nsends*nmax,&rindices2,nsends,&recv_waits2);

    156:   PetscMalloc3(n,&sindices,nsends,&send_waits,nsends,&send_status);
    157:   PetscMalloc3(n,&sindices2,nreceives,&send_waits2,nreceives,&send_status2);

    159:   /* post 1st receives: receive others requests
    160:      since we don't know how long each individual message is we
    161:      allocate the largest needed buffer for each receive. Potentially
    162:      this is a lot of wasted space.
    163:   */
    164:   for (i=0,count=0; i<nreceives; i++) {
    165:     MPI_Irecv(rindices+nmax*i,nmax,MPIU_INT,MPI_ANY_SOURCE,tag1,comm,recv_waits+count++);
    166:   }

    168:   /* do 1st sends:
    169:       1) starts[i] gives the starting index in svalues for stuff going to
    170:          the ith processor
    171:   */
    172:   start[0] = 0;
    173:   for (i=1; i<size; i++) start[i] = start[i-1] + sizes[2*i-2];
    174:   for (i=0; i<n; i++) {
    175:     j = owner[i];
    176:     if (j != rank) {
    177:       sindices[start[j]++]  = ia[i];
    178:     } else { /* compute my own map */
    179:       if (ia[i] >= owners[rank] && ia[i] < owners[rank+1]) {
    180:         ia[i] = maploc[ia[i]-owners[rank]];
    181:       } else {
    182:         ia[i] = -1;  /* ia[i] is not in the range of 0 and N-1, maps it to -1 */
    183:       }
    184:     }
    185:   }

    187:   start[0] = 0;
    188:   for (i=1; i<size; i++) start[i] = start[i-1] + sizes[2*i-2];
    189:   for (i=0,count=0; i<size; i++) {
    190:     if (sizes[2*i+1]) {
    191:       /* send my request to others */
    192:       MPI_Isend(sindices+start[i],sizes[2*i],MPIU_INT,i,tag1,comm,send_waits+count);
    193:       /* post receive for the answer of my request */
    194:       MPI_Irecv(sindices2+start[i],sizes[2*i],MPIU_INT,i,tag2,comm,recv_waits2+count);
    195:       count++;
    196:     }
    197:   }
    198:   if (nsends != count) SETERRQ2(comm,PETSC_ERR_SUP,"nsends %d != count %d",nsends,count);

    200:   /* wait on 1st sends */
    201:   if (nsends) {
    202:     MPI_Waitall(nsends,send_waits,send_status);
    203:   }

    205:   /* 1st recvs: other's requests */
    206:   for (j=0; j< nreceives; j++) {
    207:     MPI_Waitany(nreceives,recv_waits,&widx,&recv_status); /* idx: index of handle for operation that completed */
    208:     MPI_Get_count(&recv_status,MPIU_INT,&nindices);
    209:     rbuf   = rindices+nmax*widx; /* global index */
    210:     source = recv_status.MPI_SOURCE;

    212:     /* compute mapping */
    213:     sbuf = rbuf;
    214:     for (i=0; i<nindices; i++) sbuf[i] = maploc[rbuf[i]-owners[rank]];

    216:     /* send mapping back to the sender */
    217:     MPI_Isend(sbuf,nindices,MPIU_INT,source,tag2,comm,send_waits2+widx);
    218:   }

    220:   /* wait on 2nd sends */
    221:   if (nreceives) {
    222:     MPI_Waitall(nreceives,send_waits2,send_status2);
    223:   }

    225:   /* 2nd recvs: for the answer of my request */
    226:   for (j=0; j< nsends; j++) {
    227:     MPI_Waitany(nsends,recv_waits2,&widx,&recv_status);
    228:     MPI_Get_count(&recv_status,MPIU_INT,&nindices);
    229:     source = recv_status.MPI_SOURCE;
    230:     /* pack output ia[] */
    231:     rbuf  = sindices2+start[source];
    232:     count = 0;
    233:     for (i=0; i<n; i++) {
    234:       if (source == owner[i]) ia[i] = rbuf[count++];
    235:     }
    236:   }

    238:   /* free arrays */
    239:   PetscFree2(sizes,start);
    240:   PetscFree(owner);
    241:   PetscFree2(rindices,recv_waits);
    242:   PetscFree2(rindices2,recv_waits2);
    243:   PetscFree3(sindices,send_waits,send_status);
    244:   PetscFree3(sindices2,send_waits2,send_status2);
    245:   return(0);
    246: }

    250: PetscErrorCode AOPetscToApplication_MemoryScalable(AO ao,PetscInt n,PetscInt *ia)
    251: {
    252:   PetscErrorCode    ierr;
    253:   AO_MemoryScalable *aomems  = (AO_MemoryScalable*)ao->data;
    254:   PetscInt          *app_loc = aomems->app_loc;

    257:   AOMap_MemoryScalable_private(ao,n,ia,app_loc);
    258:   return(0);
    259: }

    263: PetscErrorCode AOApplicationToPetsc_MemoryScalable(AO ao,PetscInt n,PetscInt *ia)
    264: {
    265:   PetscErrorCode    ierr;
    266:   AO_MemoryScalable *aomems    = (AO_MemoryScalable*)ao->data;
    267:   PetscInt          *petsc_loc = aomems->petsc_loc;

    270:   AOMap_MemoryScalable_private(ao,n,ia,petsc_loc);
    271:   return(0);
    272: }

    274: static struct _AOOps AOOps_MemoryScalable = {
    275:   AOView_MemoryScalable,
    276:   AODestroy_MemoryScalable,
    277:   AOPetscToApplication_MemoryScalable,
    278:   AOApplicationToPetsc_MemoryScalable,
    279:   0,
    280:   0,
    281:   0,
    282:   0
    283: };

    287: PetscErrorCode  AOCreateMemoryScalable_private(MPI_Comm comm,PetscInt napp,const PetscInt from_array[],const PetscInt to_array[],AO ao, PetscInt *aomap_loc)
    288: {
    289:   PetscErrorCode    ierr;
    290:   AO_MemoryScalable *aomems = (AO_MemoryScalable*)ao->data;
    291:   PetscLayout       map     = aomems->map;
    292:   PetscInt          n_local = map->n,i,j;
    293:   PetscMPIInt       rank,size,tag;
    294:   PetscInt          *owner,*start,*sizes,nsends,nreceives;
    295:   PetscInt          nmax,count,*sindices,*rindices,idx,lastidx;
    296:   PetscInt          *owners = aomems->map->range;
    297:   MPI_Request       *send_waits,*recv_waits;
    298:   MPI_Status        recv_status;
    299:   PetscMPIInt       nindices,widx;
    300:   PetscInt          *rbuf;
    301:   PetscInt          n=napp,ip,ia;
    302:   MPI_Status        *send_status;

    305:   PetscMemzero(aomap_loc,n_local*sizeof(PetscInt));

    307:   MPI_Comm_rank(comm,&rank);
    308:   MPI_Comm_size(comm,&size);

    310:   /*  first count number of contributors (of from_array[]) to each processor */
    311:   PetscCalloc1(2*size,&sizes);
    312:   PetscMalloc1(n,&owner);

    314:   j       = 0;
    315:   lastidx = -1;
    316:   for (i=0; i<n; i++) {
    317:     /* if indices are NOT locally sorted, need to start search at the beginning */
    318:     if (lastidx > (idx = from_array[i])) j = 0;
    319:     lastidx = idx;
    320:     for (; j<size; j++) {
    321:       if (idx >= owners[j] && idx < owners[j+1]) {
    322:         sizes[2*j]  += 2; /* num of indices to be sent - in pairs (ip,ia) */
    323:         sizes[2*j+1] = 1; /* send to proc[j] */
    324:         owner[i]      = j;
    325:         break;
    326:       }
    327:     }
    328:   }
    329:   sizes[2*rank]=sizes[2*rank+1]=0; /* do not receive from self! */
    330:   nsends        = 0;
    331:   for (i=0; i<size; i++) nsends += sizes[2*i+1];

    333:   /* inform other processors of number of messages and max length*/
    334:   PetscMaxSum(comm,sizes,&nmax,&nreceives);

    336:   /* allocate arrays */
    337:   PetscObjectGetNewTag((PetscObject)ao,&tag);
    338:   PetscMalloc2(nreceives*nmax,&rindices,nreceives,&recv_waits);
    339:   PetscMalloc3(2*n,&sindices,nsends,&send_waits,nsends,&send_status);
    340:   PetscMalloc1(size,&start);

    342:   /* post receives: */
    343:   for (i=0; i<nreceives; i++) {
    344:     MPI_Irecv(rindices+nmax*i,nmax,MPIU_INT,MPI_ANY_SOURCE,tag,comm,recv_waits+i);
    345:   }

    347:   /* do sends:
    348:       1) starts[i] gives the starting index in svalues for stuff going to
    349:          the ith processor
    350:   */
    351:   start[0] = 0;
    352:   for (i=1; i<size; i++) start[i] = start[i-1] + sizes[2*i-2];
    353:   for (i=0; i<n; i++) {
    354:     j = owner[i];
    355:     if (j != rank) {
    356:       ip                   = from_array[i];
    357:       ia                   = to_array[i];
    358:       sindices[start[j]++] = ip;
    359:       sindices[start[j]++] = ia;
    360:     } else { /* compute my own map */
    361:       ip            = from_array[i] - owners[rank];
    362:       ia            = to_array[i];
    363:       aomap_loc[ip] = ia;
    364:     }
    365:   }

    367:   start[0] = 0;
    368:   for (i=1; i<size; i++) start[i] = start[i-1] + sizes[2*i-2];
    369:   for (i=0,count=0; i<size; i++) {
    370:     if (sizes[2*i+1]) {
    371:       MPI_Isend(sindices+start[i],sizes[2*i],MPIU_INT,i,tag,comm,send_waits+count);
    372:       count++;
    373:     }
    374:   }
    375:   if (nsends != count) SETERRQ2(comm,PETSC_ERR_SUP,"nsends %d != count %d",nsends,count);

    377:   /* wait on sends */
    378:   if (nsends) {
    379:     MPI_Waitall(nsends,send_waits,send_status);
    380:   }

    382:   /* recvs */
    383:   count=0;
    384:   for (j= nreceives; j>0; j--) {
    385:     MPI_Waitany(nreceives,recv_waits,&widx,&recv_status);
    386:     MPI_Get_count(&recv_status,MPIU_INT,&nindices);
    387:     rbuf = rindices+nmax*widx; /* global index */

    389:     /* compute local mapping */
    390:     for (i=0; i<nindices; i+=2) { /* pack aomap_loc */
    391:       ip            = rbuf[i] - owners[rank]; /* local index */
    392:       ia            = rbuf[i+1];
    393:       aomap_loc[ip] = ia;
    394:     }
    395:     count++;
    396:   }

    398:   PetscFree(start);
    399:   PetscFree3(sindices,send_waits,send_status);
    400:   PetscFree2(rindices,recv_waits);
    401:   PetscFree(owner);
    402:   PetscFree(sizes);
    403:   return(0);
    404: }

    408: PETSC_EXTERN PetscErrorCode AOCreate_MemoryScalable(AO ao)
    409: {
    410:   PetscErrorCode    ierr;
    411:   IS                isapp=ao->isapp,ispetsc=ao->ispetsc;
    412:   const PetscInt    *mypetsc,*myapp;
    413:   PetscInt          napp,n_local,N,i,start,*petsc,*lens,*disp;
    414:   MPI_Comm          comm;
    415:   AO_MemoryScalable *aomems;
    416:   PetscLayout       map;
    417:   PetscMPIInt       size,rank;

    420:   if (!isapp) SETERRQ(PetscObjectComm((PetscObject)ao),PETSC_ERR_ARG_WRONGSTATE,"AOSetIS() must be called before AOSetType()");
    421:   /* create special struct aomems */
    422:   PetscNewLog(ao,&aomems);
    423:   ao->data = (void*) aomems;
    424:   PetscMemcpy(ao->ops,&AOOps_MemoryScalable,sizeof(struct _AOOps));
    425:   PetscObjectChangeTypeName((PetscObject)ao,AOMEMORYSCALABLE);

    427:   /* transmit all local lengths of isapp to all processors */
    428:   PetscObjectGetComm((PetscObject)isapp,&comm);
    429:   MPI_Comm_size(comm, &size);
    430:   MPI_Comm_rank(comm, &rank);
    431:   PetscMalloc2(size,&lens,size,&disp);
    432:   ISGetLocalSize(isapp,&napp);
    433:   MPI_Allgather(&napp, 1, MPIU_INT, lens, 1, MPIU_INT, comm);

    435:   N = 0;
    436:   for (i = 0; i < size; i++) {
    437:     disp[i] = N;
    438:     N      += lens[i];
    439:   }

    441:   /* If ispetsc is 0 then use "natural" numbering */
    442:   if (napp) {
    443:     if (!ispetsc) {
    444:       start = disp[rank];
    445:       PetscMalloc1(napp+1, &petsc);
    446:       for (i=0; i<napp; i++) petsc[i] = start + i;
    447:     } else {
    448:       ISGetIndices(ispetsc,&mypetsc);
    449:       petsc = (PetscInt*)mypetsc;
    450:     }
    451:   }

    453:   /* create a map with global size N - used to determine the local sizes of ao - shall we use local napp instead of N? */
    454:   PetscLayoutCreate(comm,&map);
    455:   map->bs = 1;
    456:   map->N  = N;
    457:   PetscLayoutSetUp(map);

    459:   ao->N       = N;
    460:   ao->n       = map->n;
    461:   aomems->map = map;

    463:   /* create distributed indices app_loc: petsc->app and petsc_loc: app->petsc */
    464:   n_local = map->n;
    465:   PetscMalloc2(n_local, &aomems->app_loc,n_local,&aomems->petsc_loc);
    466:   PetscLogObjectMemory((PetscObject)ao,2*n_local*sizeof(PetscInt));
    467:   PetscMemzero(aomems->app_loc,n_local*sizeof(PetscInt));
    468:   PetscMemzero(aomems->petsc_loc,n_local*sizeof(PetscInt));
    469:   ISGetIndices(isapp,&myapp);

    471:   AOCreateMemoryScalable_private(comm,napp,petsc,myapp,ao,aomems->app_loc);
    472:   AOCreateMemoryScalable_private(comm,napp,myapp,petsc,ao,aomems->petsc_loc);

    474:   ISRestoreIndices(isapp,&myapp);
    475:   if (napp) {
    476:     if (ispetsc) {
    477:       ISRestoreIndices(ispetsc,&mypetsc);
    478:     } else {
    479:       PetscFree(petsc);
    480:     }
    481:   }
    482:   PetscFree2(lens,disp);
    483:   return(0);
    484: }

    488: /*@C
    489:    AOCreateMemoryScalable - Creates a memory scalable application ordering using two integer arrays.

    491:    Collective on MPI_Comm

    493:    Input Parameters:
    494: +  comm - MPI communicator that is to share AO
    495: .  napp - size of integer arrays
    496: .  myapp - integer array that defines an ordering
    497: -  mypetsc - integer array that defines another ordering (may be NULL to
    498:              indicate the natural ordering, that is 0,1,2,3,...)

    500:    Output Parameter:
    501: .  aoout - the new application ordering

    503:    Level: beginner

    505:     Notes: The arrays myapp and mypetsc must contain the all the integers 0 to napp-1 with no duplicates; that is there cannot be any "holes"
    506:            in the indices. Use AOCreateMapping() or AOCreateMappingIS() if you wish to have "holes" in the indices.
    507:            Comparing with AOCreateBasic(), this routine trades memory with message communication.

    509: .keywords: AO, create

    511: .seealso: AOCreateMemoryScalableIS(), AODestroy(), AOPetscToApplication(), AOApplicationToPetsc()
    512: @*/
    513: PetscErrorCode AOCreateMemoryScalable(MPI_Comm comm,PetscInt napp,const PetscInt myapp[],const PetscInt mypetsc[],AO *aoout)
    514: {
    516:   IS             isapp,ispetsc;
    517:   const PetscInt *app=myapp,*petsc=mypetsc;

    520:   ISCreateGeneral(comm,napp,app,PETSC_USE_POINTER,&isapp);
    521:   if (mypetsc) {
    522:     ISCreateGeneral(comm,napp,petsc,PETSC_USE_POINTER,&ispetsc);
    523:   } else {
    524:     ispetsc = NULL;
    525:   }
    526:   AOCreateMemoryScalableIS(isapp,ispetsc,aoout);
    527:   ISDestroy(&isapp);
    528:   if (mypetsc) {
    529:     ISDestroy(&ispetsc);
    530:   }
    531:   return(0);
    532: }

    536: /*@C
    537:    AOCreateMemoryScalableIS - Creates a memory scalable application ordering using two index sets.

    539:    Collective on IS

    541:    Input Parameters:
    542: +  isapp - index set that defines an ordering
    543: -  ispetsc - index set that defines another ordering (may be NULL to use the
    544:              natural ordering)

    546:    Output Parameter:
    547: .  aoout - the new application ordering

    549:    Level: beginner

    551:     Notes: The index sets isapp and ispetsc must contain the all the integers 0 to napp-1 (where napp is the length of the index sets) with no duplicates;
    552:            that is there cannot be any "holes".
    553:            Comparing with AOCreateBasicIS(), this routine trades memory with message communication.
    554: .keywords: AO, create

    556: .seealso: AOCreateMemoryScalable(),  AODestroy()
    557: @*/
    558: PetscErrorCode  AOCreateMemoryScalableIS(IS isapp,IS ispetsc,AO *aoout)
    559: {
    561:   MPI_Comm       comm;
    562:   AO             ao;

    565:   PetscObjectGetComm((PetscObject)isapp,&comm);
    566:   AOCreate(comm,&ao);
    567:   AOSetIS(ao,isapp,ispetsc);
    568:   AOSetType(ao,AOMEMORYSCALABLE);
    569:   AOViewFromOptions(ao,NULL,"-ao_view");
    570:   *aoout = ao;
    571:   return(0);
    572: }