Date: 2026-03-31T05:46:40+00:00

Actual source code: vecstash.c

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

      3: #define DEFAULT_STASH_SIZE 100

      5: /*
      6:   VecStashCreate_Private - Creates a stash,currently used for all the parallel
      7:   matrix implementations. The stash is where elements of a matrix destined
      8:   to be stored on other processors are kept until matrix assembly is done.

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

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

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

     24:   PetscFunctionBegin;
     25:   /* Require 2 tags, get the second using PetscCommGetNewTag() */
     26:   stash->comm = comm;
     27:   PetscCall(PetscCommGetNewTag(stash->comm, &stash->tag1));
     28:   PetscCall(PetscCommGetNewTag(stash->comm, &stash->tag2));
     29:   PetscCallMPI(MPI_Comm_size(stash->comm, &stash->size));
     30:   PetscCallMPI(MPI_Comm_rank(stash->comm, &stash->rank));

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

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

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

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

     71: /*
     72:    VecStashDestroy_Private - Destroy the stash
     73: */
     74: PetscErrorCode VecStashDestroy_Private(VecStash *stash)
     75: {
     76:   PetscFunctionBegin;
     77:   PetscCall(PetscFree2(stash->array, stash->idx));
     78:   PetscCall(PetscFree(stash->bowners));
     79:   PetscFunctionReturn(PETSC_SUCCESS);
     80: }

     82: /*
     83:    VecStashScatterEnd_Private - This is called as the final stage of
     84:    scatter. The final stages of message passing is done here, and
     85:    all the memory used for message passing is cleanedu up. This
     86:    routine also resets the stash, and deallocates the memory used
     87:    for the stash. It also keeps track of the current memory usage
     88:    so that the same value can be used the next time through.
     89: */
     90: PetscErrorCode VecStashScatterEnd_Private(VecStash *stash)
     91: {
     92:   PetscMPIInt nsends = stash->nsends;
     93:   PetscInt    oldnmax;
     94:   MPI_Status *send_status;

     96:   PetscFunctionBegin;
     97:   /* wait on sends */
     98:   if (nsends) {
     99:     PetscCall(PetscMalloc1(2 * nsends, &send_status));
    100:     PetscCallMPI(MPI_Waitall(2 * nsends, stash->send_waits, send_status));
    101:     PetscCall(PetscFree(send_status));
    102:   }

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

    112:   stash->nmax       = 0;
    113:   stash->n          = 0;
    114:   stash->reallocs   = -1;
    115:   stash->rmax       = 0;
    116:   stash->nprocessed = 0;

    118:   PetscCall(PetscFree2(stash->array, stash->idx));
    119:   stash->array = NULL;
    120:   stash->idx   = NULL;
    121:   PetscCall(PetscFree(stash->send_waits));
    122:   PetscCall(PetscFree(stash->recv_waits));
    123:   PetscCall(PetscFree2(stash->svalues, stash->sindices));
    124:   PetscCall(PetscFree2(stash->rvalues, stash->rindices));
    125:   PetscCall(PetscFree(stash->nprocs));
    126:   PetscFunctionReturn(PETSC_SUCCESS);
    127: }

    129: /*
    130:    VecStashGetInfo_Private - Gets the relevant statistics of the stash

    132:    Input Parameters:
    133:    stash    - the stash
    134:    nstash   - the size of the stash
    135:    reallocs - the number of additional mallocs incurred.

    137: */
    138: PetscErrorCode VecStashGetInfo_Private(VecStash *stash, PetscInt *nstash, PetscInt *reallocs)
    139: {
    140:   PetscFunctionBegin;
    141:   if (nstash) *nstash = stash->n * stash->bs;
    142:   if (reallocs) {
    143:     if (stash->reallocs < 0) *reallocs = 0;
    144:     else *reallocs = stash->reallocs;
    145:   }
    146:   PetscFunctionReturn(PETSC_SUCCESS);
    147: }

    149: /*
    150:    VecStashSetInitialSize_Private - Sets the initial size of the stash

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

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

    169:    Input Parameters:
    170:    stash - the stash
    171:    incr  - the minimum increase requested

    173:    Notes:
    174:    This routine doubles the currently used memory.
    175: */
    176: PetscErrorCode VecStashExpand_Private(VecStash *stash, PetscInt incr)
    177: {
    178:   PetscInt    *n_idx, newnmax, bs = stash->bs;
    179:   PetscScalar *n_array;

    181:   PetscFunctionBegin;
    182:   /* allocate a larger stash. */
    183:   if (!stash->oldnmax && !stash->nmax) { /* new stash */
    184:     if (stash->umax) newnmax = stash->umax / bs;
    185:     else newnmax = DEFAULT_STASH_SIZE / bs;
    186:   } else if (!stash->nmax) { /* reusing stash */
    187:     if (stash->umax > stash->oldnmax) newnmax = stash->umax / bs;
    188:     else newnmax = stash->oldnmax / bs;
    189:   } else newnmax = stash->nmax * 2;

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

    193:   PetscCall(PetscMalloc2(bs * newnmax, &n_array, newnmax, &n_idx));
    194:   PetscCall(PetscArraycpy(n_array, stash->array, bs * stash->nmax));
    195:   PetscCall(PetscArraycpy(n_idx, stash->idx, stash->nmax));
    196:   PetscCall(PetscFree2(stash->array, stash->idx));

    198:   stash->array = n_array;
    199:   stash->idx   = n_idx;
    200:   stash->nmax  = newnmax;
    201:   stash->reallocs++;
    202:   PetscFunctionReturn(PETSC_SUCCESS);
    203: }
    204: /*
    205:   VecStashScatterBegin_Private - Initiates the transfer of values to the
    206:   correct owners. This function goes through the stash, and check the
    207:   owners of each stashed value, and sends the values off to the owner
    208:   processors.

    210:   Input Parameters:
    211:   stash  - the stash
    212:   owners - an array of size 'no-of-procs' which gives the ownership range
    213:            for each node.

    215:   Notes:
    216:     The 'owners' array in the cased of the blocked-stash has the
    217:   ranges specified blocked global indices, and for the regular stash in
    218:   the proper global indices.
    219: */
    220: PetscErrorCode VecStashScatterBegin_Private(VecStash *stash, const PetscInt *owners)
    221: {
    222:   PetscMPIInt  size = stash->size, tag1 = stash->tag1, tag2 = stash->tag2, j, *owner, nsends, nreceives;
    223:   PetscInt    *start, *nprocs, inreceives;
    224:   PetscInt     nmax, *sindices, *rindices, idx, bs = stash->bs, lastidx;
    225:   PetscScalar *rvalues, *svalues;
    226:   MPI_Comm     comm = stash->comm;
    227:   MPI_Request *send_waits, *recv_waits;

    229:   PetscFunctionBegin;
    230:   /*  first count number of contributors to each processor */
    231:   PetscCall(PetscCalloc1(2 * size, &nprocs));
    232:   PetscCall(PetscMalloc1(stash->n, &owner));

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

    252:   /* inform other processors of number of messages and max length*/
    253:   PetscCall(PetscMaxSum(comm, nprocs, &nmax, &inreceives));
    254:   PetscCall(PetscMPIIntCast(inreceives, &nreceives));

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

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

    279:   for (PetscInt i = 0; i < stash->n; i++) {
    280:     j = owner[i];
    281:     if (bs == 1) svalues[start[j]] = stash->array[i];
    282:     else PetscCall(PetscArraycpy(svalues + bs * start[j], stash->array + bs * i, bs));
    283:     sindices[start[j]] = stash->idx[i];
    284:     start[j]++;
    285:   }
    286:   start[0] = 0;
    287:   for (PetscMPIInt i = 1; i < size; i++) start[i] = start[i - 1] + nprocs[2 * i - 2];

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

    300:   stash->nprocs     = nprocs;
    301:   stash->svalues    = svalues;
    302:   stash->sindices   = sindices;
    303:   stash->rvalues    = rvalues;
    304:   stash->rindices   = rindices;
    305:   stash->nsends     = nsends;
    306:   stash->nrecvs     = nreceives;
    307:   stash->send_waits = send_waits;
    308:   stash->recv_waits = recv_waits;
    309:   stash->rmax       = nmax;
    310:   PetscFunctionReturn(PETSC_SUCCESS);
    311: }

    313: /*
    314:    VecStashScatterGetMesg_Private - This function waits on the receives posted
    315:    in the function VecStashScatterBegin_Private() and returns one message at
    316:    a time to the calling function. If no messages are left, it indicates this
    317:    by setting flg = 0, else it sets flg = 1.

    319:    Input Parameters:
    320:    stash - the stash

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

    339:   PetscFunctionBegin;
    340:   *flg = 0; /* When a message is discovered this is reset to 1 */
    341:   /* Return if no more messages to process */
    342:   if (stash->nprocessed == stash->nrecvs) PetscFunctionReturn(PETSC_SUCCESS);

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

    359:     /* Check if we have both the messages from this proc */
    360:     i1 = flg_v[2 * recv_status.MPI_SOURCE];
    361:     i2 = flg_v[2 * recv_status.MPI_SOURCE + 1];
    362:     if (i1 != -1 && i2 != -1) {
    363:       *rows = stash->rindices + i2 * stash->rmax;
    364:       *vals = stash->rvalues + i1 * bs * stash->rmax;
    365:       *flg  = 1;
    366:       stash->nprocessed++;
    367:       match_found = PETSC_TRUE;
    368:     }
    369:   }
    370:   PetscFunctionReturn(PETSC_SUCCESS);
    371: }

    373: /*
    374:  * Sort the stash, removing duplicates (combining as appropriate).
    375:  */
    376: PetscErrorCode VecStashSortCompress_Private(VecStash *stash)
    377: {
    378:   PetscInt i, j, bs = stash->bs;

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

    410:     /* Out-of-place copy of arr */
    411:     PetscCall(PetscArraycpy(arr, stash->array + perm[0] * bs, bs));
    412:     for (i = 1, j = 0; i < stash->n; i++) {
    413:       PetscInt k;
    414:       if (stash->idx[i] == stash->idx[j]) {
    415:         switch (stash->insertmode) {
    416:         case ADD_VALUES:
    417:           for (k = 0; k < bs; k++) arr[j * bs + k] += stash->array[perm[i] * bs + k];
    418:           break;
    419:         case INSERT_VALUES:
    420:           for (k = 0; k < bs; k++) arr[j * bs + k] = stash->array[perm[i] * bs + k];
    421:           break;
    422:         default:
    423:           SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "Insert mode not supported 0x%x", stash->insertmode);
    424:         }
    425:       } else {
    426:         j++;
    427:         stash->idx[j] = stash->idx[i];
    428:         for (k = 0; k < bs; k++) arr[j * bs + k] = stash->array[perm[i] * bs + k];
    429:       }
    430:     }
    431:     stash->n = j + 1;
    432:     PetscCall(PetscArraycpy(stash->array, arr, stash->n * bs));
    433:     PetscCall(PetscFree2(perm, arr));
    434:   }
    435:   PetscFunctionReturn(PETSC_SUCCESS);
    436: }

    438: PetscErrorCode VecStashGetOwnerList_Private(VecStash *stash, PetscLayout map, PetscMPIInt *nowners, PetscMPIInt **owners)
    439: {
    440:   PetscInt       i, bs = stash->bs;
    441:   PetscMPIInt    r;
    442:   PetscSegBuffer seg;

    444:   PetscFunctionBegin;
    445:   PetscCheck(bs == 1 || bs == map->bs, map->comm, PETSC_ERR_PLIB, "Stash block size %" PetscInt_FMT " does not match layout block size %" PetscInt_FMT, bs, map->bs);
    446:   PetscCall(PetscSegBufferCreate(sizeof(PetscMPIInt), 50, &seg));
    447:   *nowners = 0;
    448:   for (i = 0, r = -1; i < stash->n; i++) {
    449:     if (stash->idx[i] * bs >= map->range[r + 1]) {
    450:       PetscMPIInt *rank;
    451:       PetscCall(PetscSegBufferGet(seg, 1, &rank));
    452:       PetscCall(PetscLayoutFindOwner(map, stash->idx[i] * bs, &r));
    453:       *rank = r;
    454:       (*nowners)++;
    455:     }
    456:   }
    457:   PetscCall(PetscSegBufferExtractAlloc(seg, owners));
    458:   PetscCall(PetscSegBufferDestroy(&seg));
    459:   PetscFunctionReturn(PETSC_SUCCESS);
    460: }