Date: 2022-03-04T17:37:20+00:00

Actual source code: vecstash.c

      2: #include <petsc/private/vecimpl.h>

      4: #define DEFAULT_STASH_SIZE   100

      6: /*
      7:   VecStashCreate_Private - Creates a stash,currently used for all the parallel
      8:   matrix implementations. The stash is where elements of a matrix destined
      9:   to be stored on other processors are kept until matrix assembly is done.

     11:   This is a simple minded stash. Simply adds entries to end of stash.

     13:   Input Parameters:
     14:   comm - communicator, required for scatters.
     15:   bs   - stash block size. used when stashing blocks of values

     17:   Output Parameters:
     18:   stash    - the newly created stash
     19: */
     20: PetscErrorCode VecStashCreate_Private(MPI_Comm comm,PetscInt bs,VecStash *stash)
     21: {
     23:   PetscInt       max,*opt,nopt;
     24:   PetscBool      flg;

     27:   /* Require 2 tags, get the second using PetscCommGetNewTag() */
     28:   stash->comm = comm;
     29:   PetscCommGetNewTag(stash->comm,&stash->tag1);
     30:   PetscCommGetNewTag(stash->comm,&stash->tag2);
     31:   MPI_Comm_size(stash->comm,&stash->size);
     32:   MPI_Comm_rank(stash->comm,&stash->rank);

     34:   nopt = stash->size;
     35:   PetscMalloc1(nopt,&opt);
     36:   PetscOptionsGetIntArray(NULL,NULL,"-vecstash_initial_size",opt,&nopt,&flg);
     37:   if (flg) {
     38:     if (nopt == 1)                max = opt[0];
     39:     else if (nopt == stash->size) max = opt[stash->rank];
     40:     else if (stash->rank < nopt)  max = opt[stash->rank];
     41:     else                          max = 0; /* use default */
     42:     stash->umax = max;
     43:   } else {
     44:     stash->umax = 0;
     45:   }
     46:   PetscFree(opt);

     48:   if (bs <= 0) bs = 1;

     50:   stash->bs       = bs;
     51:   stash->nmax     = 0;
     52:   stash->oldnmax  = 0;
     53:   stash->n        = 0;
     54:   stash->reallocs = -1;
     55:   stash->idx      = NULL;
     56:   stash->array    = NULL;

     58:   stash->send_waits   = NULL;
     59:   stash->recv_waits   = NULL;
     60:   stash->send_status  = NULL;
     61:   stash->nsends       = 0;
     62:   stash->nrecvs       = 0;
     63:   stash->svalues      = NULL;
     64:   stash->rvalues      = NULL;
     65:   stash->rmax         = 0;
     66:   stash->nprocs       = NULL;
     67:   stash->nprocessed   = 0;
     68:   stash->donotstash   = PETSC_FALSE;
     69:   stash->ignorenegidx = PETSC_FALSE;
     70:   return(0);
     71: }

     73: /*
     74:    VecStashDestroy_Private - Destroy the stash
     75: */
     76: PetscErrorCode VecStashDestroy_Private(VecStash *stash)
     77: {

     81:   PetscFree2(stash->array,stash->idx);
     82:   PetscFree(stash->bowners);
     83:   return(0);
     84: }

     86: /*
     87:    VecStashScatterEnd_Private - This is called as the fial stage of
     88:    scatter. The final stages of message passing is done here, and
     89:    all the memory used for message passing is cleanedu up. This
     90:    routine also resets the stash, and deallocates the memory used
     91:    for the stash. It also keeps track of the current memory usage
     92:    so that the same value can be used the next time through.
     93: */
     94: PetscErrorCode VecStashScatterEnd_Private(VecStash *stash)
     95: {
     97:   PetscInt       nsends=stash->nsends,oldnmax;
     98:   MPI_Status     *send_status;

    101:   /* wait on sends */
    102:   if (nsends) {
    103:     PetscMalloc1(2*nsends,&send_status);
    104:     MPI_Waitall(2*nsends,stash->send_waits,send_status);
    105:     PetscFree(send_status);
    106:   }

    108:   /* Now update nmaxold to be app 10% more than max n, this way the
    109:      wastage of space is reduced the next time this stash is used.
    110:      Also update the oldmax, only if it increases */
    111:   if (stash->n) {
    112:     oldnmax = ((PetscInt)(stash->n * 1.1) + 5)*stash->bs;
    113:     if (oldnmax > stash->oldnmax) stash->oldnmax = oldnmax;
    114:   }

    116:   stash->nmax       = 0;
    117:   stash->n          = 0;
    118:   stash->reallocs   = -1;
    119:   stash->rmax       = 0;
    120:   stash->nprocessed = 0;

    122:   PetscFree2(stash->array,stash->idx);
    123:   stash->array = NULL;
    124:   stash->idx   = NULL;
    125:   PetscFree(stash->send_waits);
    126:   PetscFree(stash->recv_waits);
    127:   PetscFree2(stash->svalues,stash->sindices);
    128:   PetscFree2(stash->rvalues,stash->rindices);
    129:   PetscFree(stash->nprocs);
    130:   return(0);
    131: }

    133: /*
    134:    VecStashGetInfo_Private - Gets the relavant statistics of the stash

    136:    Input Parameters:
    137:    stash    - the stash
    138:    nstash   - the size of the stash
    139:    reallocs - the number of additional mallocs incurred.

    141: */
    142: PetscErrorCode VecStashGetInfo_Private(VecStash *stash,PetscInt *nstash,PetscInt *reallocs)
    143: {
    145:   if (nstash) *nstash = stash->n*stash->bs;
    146:   if (reallocs) {
    147:     if (stash->reallocs < 0) *reallocs = 0;
    148:     else                     *reallocs = stash->reallocs;
    149:   }
    150:   return(0);
    151: }

    153: /*
    154:    VecStashSetInitialSize_Private - Sets the initial size of the stash

    156:    Input Parameters:
    157:    stash  - the stash
    158:    max    - the value that is used as the max size of the stash.
    159:             this value is used while allocating memory. It specifies
    160:             the number of vals stored, even with the block-stash
    161: */
    162: PetscErrorCode VecStashSetInitialSize_Private(VecStash *stash,PetscInt max)
    163: {
    165:   stash->umax = max;
    166:   return(0);
    167: }

    169: /* VecStashExpand_Private - Expand the stash. This function is called
    170:    when the space in the stash is not sufficient to add the new values
    171:    being inserted into the stash.

    173:    Input Parameters:
    174:    stash - the stash
    175:    incr  - the minimum increase requested

    177:    Notes:
    178:    This routine doubles the currently used memory.
    179: */
    180: PetscErrorCode VecStashExpand_Private(VecStash *stash,PetscInt incr)
    181: {
    183:   PetscInt       *n_idx,newnmax,bs=stash->bs;
    184:   PetscScalar    *n_array;

    187:   /* allocate a larger stash. */
    188:   if (!stash->oldnmax && !stash->nmax) { /* new stash */
    189:     if (stash->umax)                  newnmax = stash->umax/bs;
    190:     else                              newnmax = DEFAULT_STASH_SIZE/bs;
    191:   } else if (!stash->nmax) { /* resuing stash */
    192:     if (stash->umax > stash->oldnmax) newnmax = stash->umax/bs;
    193:     else                              newnmax = stash->oldnmax/bs;
    194:   } else                              newnmax = stash->nmax*2;

    196:   if (newnmax  < (stash->nmax + incr)) newnmax += 2*incr;

    198:   PetscMalloc2(bs*newnmax,&n_array,newnmax,&n_idx);
    199:   PetscMemcpy(n_array,stash->array,bs*stash->nmax*sizeof(PetscScalar));
    200:   PetscMemcpy(n_idx,stash->idx,stash->nmax*sizeof(PetscInt));
    201:   PetscFree2(stash->array,stash->idx);

    203:   stash->array = n_array;
    204:   stash->idx   = n_idx;
    205:   stash->nmax  = newnmax;
    206:   stash->reallocs++;
    207:   return(0);
    208: }
    209: /*
    210:   VecStashScatterBegin_Private - Initiates the transfer of values to the
    211:   correct owners. This function goes through the stash, and check the
    212:   owners of each stashed value, and sends the values off to the owner
    213:   processors.

    215:   Input Parameters:
    216:   stash  - the stash
    217:   owners - an array of size 'no-of-procs' which gives the ownership range
    218:            for each node.

    220:   Notes:
    221:     The 'owners' array in the cased of the blocked-stash has the
    222:   ranges specified blocked global indices, and for the regular stash in
    223:   the proper global indices.
    224: */
    225: PetscErrorCode VecStashScatterBegin_Private(VecStash *stash,PetscInt *owners)
    226: {
    228:   PetscMPIInt    size = stash->size,tag1=stash->tag1,tag2=stash->tag2;
    229:   PetscInt       *owner,*start,*nprocs,nsends,nreceives;
    230:   PetscInt       nmax,count,*sindices,*rindices,i,j,idx,bs=stash->bs,lastidx;
    231:   PetscScalar    *rvalues,*svalues;
    232:   MPI_Comm       comm = stash->comm;
    233:   MPI_Request    *send_waits,*recv_waits;

    236:   /*  first count number of contributors to each processor */
    237:   PetscCalloc1(2*size,&nprocs);
    238:   PetscMalloc1(stash->n,&owner);

    240:   j       = 0;
    241:   lastidx = -1;
    242:   for (i=0; i<stash->n; i++) {
    243:     /* if indices are NOT locally sorted, need to start search at the beginning */
    244:     if (lastidx > (idx = stash->idx[i])) j = 0;
    245:     lastidx = idx;
    246:     for (; j<size; j++) {
    247:       if (idx >= owners[j] && idx < owners[j+1]) {
    248:         nprocs[2*j]++; nprocs[2*j+1] = 1; owner[i] = j; break;
    249:       }
    250:     }
    251:   }
    252:   nsends = 0;
    253:   for (i=0; i<size; i++) nsends += nprocs[2*i+1];

    255:   /* inform other processors of number of messages and max length*/
    256:   PetscMaxSum(comm,nprocs,&nmax,&nreceives);

    258:   /* post receives:
    259:      since we don't know how long each individual message is we
    260:      allocate the largest needed buffer for each receive. Potentially
    261:      this is a lot of wasted space.
    262:   */
    263:   PetscMalloc2(nreceives*nmax*bs,&rvalues,nreceives*nmax,&rindices);
    264:   PetscMalloc1(2*nreceives,&recv_waits);
    265:   for (i=0,count=0; i<nreceives; i++) {
    266:     MPI_Irecv(rvalues+bs*nmax*i,bs*nmax,MPIU_SCALAR,MPI_ANY_SOURCE,tag1,comm,recv_waits+count++);
    267:     MPI_Irecv(rindices+nmax*i,nmax,MPIU_INT,MPI_ANY_SOURCE,tag2,comm,recv_waits+count++);
    268:   }

    270:   /* do sends:
    271:       1) starts[i] gives the starting index in svalues for stuff going to
    272:          the ith processor
    273:   */
    274:   PetscMalloc2(stash->n*bs,&svalues,stash->n,&sindices);
    275:   PetscMalloc1(2*nsends,&send_waits);
    276:   PetscMalloc1(size,&start);
    277:   /* use 2 sends the first with all_v, the next with all_i */
    278:   start[0] = 0;
    279:   for (i=1; i<size; i++) start[i] = start[i-1] + nprocs[2*i-2];

    281:   for (i=0; i<stash->n; i++) {
    282:     j = owner[i];
    283:     if (bs == 1) svalues[start[j]] = stash->array[i];
    284:     else {
    285:       PetscMemcpy(svalues+bs*start[j],stash->array+bs*i,bs*sizeof(PetscScalar));
    286:     }
    287:     sindices[start[j]] = stash->idx[i];
    288:     start[j]++;
    289:   }
    290:   start[0] = 0;
    291:   for (i=1; i<size; i++) start[i] = start[i-1] + nprocs[2*i-2];

    293:   for (i=0,count=0; i<size; i++) {
    294:     if (nprocs[2*i+1]) {
    295:       MPI_Isend(svalues+bs*start[i],bs*nprocs[2*i],MPIU_SCALAR,i,tag1,comm,send_waits+count++);
    296:       MPI_Isend(sindices+start[i],nprocs[2*i],MPIU_INT,i,tag2,comm,send_waits+count++);
    297:     }
    298:   }
    299:   PetscFree(owner);
    300:   PetscFree(start);
    301:   /* This memory is reused in scatter end  for a different purpose*/
    302:   for (i=0; i<2*size; i++) nprocs[i] = -1;

    304:   stash->nprocs     = nprocs;
    305:   stash->svalues    = svalues;
    306:   stash->sindices   = sindices;
    307:   stash->rvalues    = rvalues;
    308:   stash->rindices   = rindices;
    309:   stash->nsends     = nsends;
    310:   stash->nrecvs     = nreceives;
    311:   stash->send_waits = send_waits;
    312:   stash->recv_waits = recv_waits;
    313:   stash->rmax       = nmax;
    314:   return(0);
    315: }

    317: /*
    318:    VecStashScatterGetMesg_Private - This function waits on the receives posted
    319:    in the function VecStashScatterBegin_Private() and returns one message at
    320:    a time to the calling function. If no messages are left, it indicates this
    321:    by setting flg = 0, else it sets flg = 1.

    323:    Input Parameters:
    324:    stash - the stash

    326:    Output Parameters:
    327:    nvals - the number of entries in the current message.
    328:    rows  - an array of row indices (or blocked indices) corresponding to the values
    329:    cols  - an array of columnindices (or blocked indices) corresponding to the values
    330:    vals  - the values
    331:    flg   - 0 indicates no more message left, and the current call has no values associated.
    332:            1 indicates that the current call successfully received a message, and the
    333:              other output parameters nvals,rows,cols,vals are set appropriately.
    334: */
    335: PetscErrorCode VecStashScatterGetMesg_Private(VecStash *stash,PetscMPIInt *nvals,PetscInt **rows,PetscScalar **vals,PetscInt *flg)
    336: {
    338:   PetscMPIInt    i = 0; /* dummy value so MPI-Uni doesn't think it is not set */
    339:   PetscInt       *flg_v;
    340:   PetscInt       i1,i2,bs=stash->bs;
    341:   MPI_Status     recv_status;
    342:   PetscBool      match_found = PETSC_FALSE;

    345:   *flg = 0; /* When a message is discovered this is reset to 1 */
    346:   /* Return if no more messages to process */
    347:   if (stash->nprocessed == stash->nrecvs) return(0);

    349:   flg_v = stash->nprocs;
    350:   /* If a matching pair of receives are found, process them, and return the data to
    351:      the calling function. Until then keep receiving messages */
    352:   while (!match_found) {
    353:     MPI_Waitany(2*stash->nrecvs,stash->recv_waits,&i,&recv_status);
    354:     /* Now pack the received message into a structure which is useable by others */
    355:     if (i % 2) {
    356:       MPI_Get_count(&recv_status,MPIU_INT,nvals);
    357:       flg_v[2*recv_status.MPI_SOURCE+1] = i/2;
    358:     } else {
    359:       MPI_Get_count(&recv_status,MPIU_SCALAR,nvals);
    360:       flg_v[2*recv_status.MPI_SOURCE] = i/2;
    361:       *nvals = *nvals/bs;
    362:     }

    364:     /* Check if we have both the messages from this proc */
    365:     i1 = flg_v[2*recv_status.MPI_SOURCE];
    366:     i2 = flg_v[2*recv_status.MPI_SOURCE+1];
    367:     if (i1 != -1 && i2 != -1) {
    368:       *rows = stash->rindices + i2*stash->rmax;
    369:       *vals = stash->rvalues + i1*bs*stash->rmax;
    370:       *flg  = 1;
    371:       stash->nprocessed++;
    372:       match_found = PETSC_TRUE;
    373:     }
    374:   }
    375:   return(0);
    376: }

    378: /*
    379:  * Sort the stash, removing duplicates (combining as appropriate).
    380:  */
    381: PetscErrorCode VecStashSortCompress_Private(VecStash *stash)
    382: {
    384:   PetscInt i,j,bs = stash->bs;

    387:   if (!stash->n) return(0);
    388:   if (bs == 1) {
    389:     PetscSortIntWithScalarArray(stash->n,stash->idx,stash->array);
    390:     for (i=1,j=0; i<stash->n; i++) {
    391:       if (stash->idx[i] == stash->idx[j]) {
    392:         switch (stash->insertmode) {
    393:         case ADD_VALUES:
    394:           stash->array[j] += stash->array[i];
    395:           break;
    396:         case INSERT_VALUES:
    397:           stash->array[j] = stash->array[i];
    398:           break;
    399:         default: SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_SUP,"Insert mode not supported 0x%x",stash->insertmode);
    400:         }
    401:       } else {
    402:         j++;
    403:         stash->idx[j]   = stash->idx[i];
    404:         stash->array[j] = stash->array[i];
    405:       }
    406:     }
    407:     stash->n = j + 1;
    408:   } else {                      /* block stash */
    409:     PetscInt *perm = NULL;
    410:     PetscScalar *arr;
    411:     PetscMalloc2(stash->n,&perm,stash->n*bs,&arr);
    412:     for (i=0; i<stash->n; i++) perm[i] = i;
    413:     PetscSortIntWithArray(stash->n,stash->idx,perm);

    415:     /* Out-of-place copy of arr */
    416:     PetscMemcpy(arr,stash->array+perm[0]*bs,bs*sizeof(PetscScalar));
    417:     for (i=1,j=0; i<stash->n; i++) {
    418:       PetscInt k;
    419:       if (stash->idx[i] == stash->idx[j]) {
    420:         switch (stash->insertmode) {
    421:         case ADD_VALUES:
    422:           for (k=0; k<bs; k++) arr[j*bs+k] += stash->array[perm[i]*bs+k];
    423:           break;
    424:         case INSERT_VALUES:
    425:           for (k=0; k<bs; k++) arr[j*bs+k] = stash->array[perm[i]*bs+k];
    426:           break;
    427:         default: SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_SUP,"Insert mode not supported 0x%x",stash->insertmode);
    428:         }
    429:       } else {
    430:         j++;
    431:         stash->idx[j] = stash->idx[i];
    432:         for (k=0; k<bs; k++) arr[j*bs+k] = stash->array[perm[i]*bs+k];
    433:       }
    434:     }
    435:     stash->n = j + 1;
    436:     PetscMemcpy(stash->array,arr,stash->n*bs*sizeof(PetscScalar));
    437:     PetscFree2(perm,arr);
    438:   }
    439:   return(0);
    440: }

    442: PetscErrorCode VecStashGetOwnerList_Private(VecStash *stash,PetscLayout map,PetscMPIInt *nowners,PetscMPIInt **owners)
    443: {
    444:   PetscInt       i,bs = stash->bs;
    445:   PetscMPIInt    r;
    446:   PetscSegBuffer seg;

    450:   if (bs != 1 && bs != map->bs) SETERRQ2(map->comm,PETSC_ERR_PLIB,"Stash block size %D does not match layout block size %D",bs,map->bs);
    451:   PetscSegBufferCreate(sizeof(PetscMPIInt),50,&seg);
    452:   *nowners = 0;
    453:   for (i=0,r=-1; i<stash->n; i++) {
    454:     if (stash->idx[i]*bs >= map->range[r+1]) {
    455:       PetscMPIInt *rank;
    456:       PetscSegBufferGet(seg,1,&rank);
    457:       PetscLayoutFindOwner(map,stash->idx[i]*bs,&r);
    458:       *rank = r;
    459:       (*nowners)++;
    460:     }
    461:   }
    462:   PetscSegBufferExtractAlloc(seg,owners);
    463:   PetscSegBufferDestroy(&seg);
    464:   return(0);
    465: }