Date: 2022-08-02T03:13:33+00:00

Actual source code: mpihip.hip.cpp

      2: /*
      3:    This file contains routines for Parallel vector operations.
      4:  */
      5: #define PETSC_SKIP_SPINLOCK

      7: #include <petscconf.h>
      8: #include <../src/vec/vec/impls/mpi/pvecimpl.h>
      9: #include <petsc/private/hipvecimpl.h>

     11: /*MC
     12:    VECHIP - VECHIP = "hip" - A VECSEQHIP on a single-process communicator, and VECMPIHIP otherwise.

     14:    Options Database Keys:
     15: . -vec_type hip - sets the vector type to VECHIP during a call to VecSetFromOptions()

     17:   Level: beginner

     19: .seealso: VecCreate(), VecSetType(), VecSetFromOptions(), VecCreateMPIWithArray(), VECSEQHIP, VECMPIHIP, VECSTANDARD, VecType, VecCreateMPI(), VecSetPinnedMemoryMin()
     20: M*/

     22: PetscErrorCode VecDestroy_MPIHIP(Vec v)
     23: {
     24:   Vec_MPI        *vecmpi = (Vec_MPI*)v->data;
     25:   Vec_HIP        *vechip;

     27:   if (v->spptr) {
     28:     vechip = (Vec_HIP*)v->spptr;
     29:     if (vechip->GPUarray_allocated) {
     30:       hipFree(vechip->GPUarray_allocated);
     31:       vechip->GPUarray_allocated = NULL;
     32:     }
     33:     if (vechip->stream) {
     34:       hipStreamDestroy(vechip->stream);
     35:     }
     36:     if (v->pinned_memory) {
     37:       PetscMallocSetHIPHost();
     38:       PetscFree(vecmpi->array_allocated);
     39:       PetscMallocResetHIPHost();
     40:       v->pinned_memory = PETSC_FALSE;
     41:     }
     42:     PetscFree(v->spptr);
     43:   }
     44:   VecDestroy_MPI(v);
     45:   return 0;
     46: }

     48: PetscErrorCode VecNorm_MPIHIP(Vec xin,NormType type,PetscReal *z)
     49: {
     50:   PetscReal      sum,work = 0.0;

     52:   if (type == NORM_2 || type == NORM_FROBENIUS) {
     53:     VecNorm_SeqHIP(xin,NORM_2,&work);
     54:     work *= work;
     55:     MPIU_Allreduce(&work,&sum,1,MPIU_REAL,MPIU_SUM,PetscObjectComm((PetscObject)xin));
     56:     *z    = PetscSqrtReal(sum);
     57:   } else if (type == NORM_1) {
     58:     /* Find the local part */
     59:     VecNorm_SeqHIP(xin,NORM_1,&work);
     60:     /* Find the global max */
     61:     MPIU_Allreduce(&work,z,1,MPIU_REAL,MPIU_SUM,PetscObjectComm((PetscObject)xin));
     62:   } else if (type == NORM_INFINITY) {
     63:     /* Find the local max */
     64:     VecNorm_SeqHIP(xin,NORM_INFINITY,&work);
     65:     /* Find the global max */
     66:     MPIU_Allreduce(&work,z,1,MPIU_REAL,MPIU_MAX,PetscObjectComm((PetscObject)xin));
     67:   } else if (type == NORM_1_AND_2) {
     68:     PetscReal temp[2];
     69:     VecNorm_SeqHIP(xin,NORM_1,temp);
     70:     VecNorm_SeqHIP(xin,NORM_2,temp+1);
     71:     temp[1] = temp[1]*temp[1];
     72:     MPIU_Allreduce(temp,z,2,MPIU_REAL,MPIU_SUM,PetscObjectComm((PetscObject)xin));
     73:     z[1] = PetscSqrtReal(z[1]);
     74:   }
     75:   return 0;
     76: }

     78: PetscErrorCode VecDot_MPIHIP(Vec xin,Vec yin,PetscScalar *z)
     79: {
     80:   PetscScalar    sum,work;

     82:   VecDot_SeqHIP(xin,yin,&work);
     83:   MPIU_Allreduce(&work,&sum,1,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)xin));
     84:   *z   = sum;
     85:   return 0;
     86: }

     88: PetscErrorCode VecTDot_MPIHIP(Vec xin,Vec yin,PetscScalar *z)
     89: {
     90:   PetscScalar    sum,work;

     92:   VecTDot_SeqHIP(xin,yin,&work);
     93:   MPIU_Allreduce(&work,&sum,1,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)xin));
     94:   *z   = sum;
     95:   return 0;
     96: }

     98: PetscErrorCode VecMDot_MPIHIP(Vec xin,PetscInt nv,const Vec y[],PetscScalar *z)
     99: {
    100:   PetscScalar    awork[128],*work = awork;

    102:   if (nv > 128) {
    103:     PetscMalloc1(nv,&work);
    104:   }
    105:   VecMDot_SeqHIP(xin,nv,y,work);
    106:   MPIU_Allreduce(work,z,nv,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)xin));
    107:   if (nv > 128) {
    108:     PetscFree(work);
    109:   }
    110:   return 0;
    111: }

    113: /*MC
    114:    VECMPIHIP - VECMPIHIP = "mpihip" - The basic parallel vector, modified to use HIP

    116:    Options Database Keys:
    117: . -vec_type mpihip - sets the vector type to VECMPIHIP during a call to VecSetFromOptions()

    119:   Level: beginner

    121: .seealso: VecCreate(), VecSetType(), VecSetFromOptions(), VecCreateMPIWithArray(), VECMPI, VecType, VecCreateMPI(), VecSetPinnedMemoryMin()
    122: M*/

    124: PetscErrorCode VecDuplicate_MPIHIP(Vec win,Vec *v)
    125: {
    126:   Vec_MPI        *vw,*w = (Vec_MPI*)win->data;
    127:   PetscScalar    *array;

    129:   VecCreate(PetscObjectComm((PetscObject)win),v);
    130:   PetscLayoutReference(win->map,&(*v)->map);

    132:   VecCreate_MPIHIP_Private(*v,PETSC_TRUE,w->nghost,0);
    133:   vw   = (Vec_MPI*)(*v)->data;
    134:   PetscMemcpy((*v)->ops,win->ops,sizeof(struct _VecOps));

    136:   /* save local representation of the parallel vector (and scatter) if it exists */
    137:   if (w->localrep) {
    138:     VecGetArray(*v,&array);
    139:     VecCreateSeqWithArray(PETSC_COMM_SELF,1,win->map->n+w->nghost,array,&vw->localrep);
    140:     PetscMemcpy(vw->localrep->ops,w->localrep->ops,sizeof(struct _VecOps));
    141:     VecRestoreArray(*v,&array);
    142:     PetscLogObjectParent((PetscObject)*v,(PetscObject)vw->localrep);
    143:     vw->localupdate = w->localupdate;
    144:     if (vw->localupdate) {
    145:       PetscObjectReference((PetscObject)vw->localupdate);
    146:     }
    147:   }

    149:   /* New vector should inherit stashing property of parent */
    150:   (*v)->stash.donotstash   = win->stash.donotstash;
    151:   (*v)->stash.ignorenegidx = win->stash.ignorenegidx;

    153:   /* change type_name appropriately */
    154:   VecHIPAllocateCheck(*v);
    155:   PetscObjectChangeTypeName((PetscObject)(*v),VECMPIHIP);

    157:   PetscObjectListDuplicate(((PetscObject)win)->olist,&((PetscObject)(*v))->olist);
    158:   PetscFunctionListDuplicate(((PetscObject)win)->qlist,&((PetscObject)(*v))->qlist);
    159:   (*v)->map->bs   = PetscAbs(win->map->bs);
    160:   (*v)->bstash.bs = win->bstash.bs;
    161:   return 0;
    162: }

    164: PetscErrorCode VecDotNorm2_MPIHIP(Vec s,Vec t,PetscScalar *dp,PetscScalar *nm)
    165: {
    166:   PetscScalar    work[2],sum[2];

    168:   VecDotNorm2_SeqHIP(s,t,work,work+1);
    169:   MPIU_Allreduce(&work,&sum,2,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)s));
    170:   *dp  = sum[0];
    171:   *nm  = sum[1];
    172:   return 0;
    173: }

    175: PetscErrorCode VecCreate_MPIHIP(Vec vv)
    176: {
    177:   PetscDeviceInitialize(PETSC_DEVICE_HIP);
    178:   PetscLayoutSetUp(vv->map);
    179:   VecHIPAllocateCheck(vv);
    180:   VecCreate_MPIHIP_Private(vv,PETSC_FALSE,0,((Vec_HIP*)vv->spptr)->GPUarray_allocated);
    181:   VecHIPAllocateCheckHost(vv);
    182:   VecSet(vv,0.0);
    183:   VecSet_Seq(vv,0.0);
    184:   vv->offloadmask = PETSC_OFFLOAD_BOTH;
    185:   return 0;
    186: }

    188: PetscErrorCode VecCreate_HIP(Vec v)
    189: {
    190:   PetscMPIInt    size;

    192:   MPI_Comm_size(PetscObjectComm((PetscObject)v),&size);
    193:   if (size == 1) {
    194:     VecSetType(v,VECSEQHIP);
    195:   } else {
    196:     VecSetType(v,VECMPIHIP);
    197:   }
    198:   return 0;
    199: }

    201: /*@
    202:  VecCreateMPIHIP - Creates a standard, parallel array-style vector for HIP devices.

    204:  Collective

    206:  Input Parameters:
    207:  +  comm - the MPI communicator to use
    208:  .  n - local vector length (or PETSC_DECIDE to have calculated if N is given)
    209:  -  N - global vector length (or PETSC_DETERMINE to have calculated if n is given)

    211:     Output Parameter:
    212:  .  v - the vector

    214:     Notes:
    215:     Use VecDuplicate() or VecDuplicateVecs() to form additional vectors of the
    216:     same type as an existing vector.

    218:     Level: intermediate

    220:  .seealso: VecCreateMPIHIPWithArray(), VecCreateMPIHIPWithArrays(), VecCreateSeqHIP(), VecCreateSeq(),
    221:            VecCreateMPI(), VecCreate(), VecDuplicate(), VecDuplicateVecs(), VecCreateGhost(),
    222:            VecCreateMPIWithArray(), VecCreateGhostWithArray(), VecMPISetGhost()

    224:  @*/
    225:  PetscErrorCode VecCreateMPIHIP(MPI_Comm comm,PetscInt n,PetscInt N,Vec *v)
    226:  {
    227:    VecCreate(comm,v);
    228:    VecSetSizes(*v,n,N);
    229:    VecSetType(*v,VECMPIHIP);
    230:    return 0;
    231:  }

    233: /*@C
    234:    VecCreateMPIHIPWithArray - Creates a parallel, array-style vector,
    235:    where the user provides the GPU array space to store the vector values.

    237:    Collective

    239:    Input Parameters:
    240: +  comm  - the MPI communicator to use
    241: .  bs    - block size, same meaning as VecSetBlockSize()
    242: .  n     - local vector length, cannot be PETSC_DECIDE
    243: .  N     - global vector length (or PETSC_DECIDE to have calculated)
    244: -  array - the user provided GPU array to store the vector values

    246:    Output Parameter:
    247: .  vv - the vector

    249:    Notes:
    250:    Use VecDuplicate() or VecDuplicateVecs() to form additional vectors of the
    251:    same type as an existing vector.

    253:    If the user-provided array is NULL, then VecHIPPlaceArray() can be used
    254:    at a later stage to SET the array for storing the vector values.

    256:    PETSc does NOT free the array when the vector is destroyed via VecDestroy().
    257:    The user should not free the array until the vector is destroyed.

    259:    Level: intermediate

    261: .seealso: VecCreateSeqHIPWithArray(), VecCreateMPIWithArray(), VecCreateSeqWithArray(),
    262:           VecCreate(), VecDuplicate(), VecDuplicateVecs(), VecCreateGhost(),
    263:           VecCreateMPI(), VecCreateGhostWithArray(), VecPlaceArray()

    265: @*/
    266: PetscErrorCode  VecCreateMPIHIPWithArray(MPI_Comm comm,PetscInt bs,PetscInt n,PetscInt N,const PetscScalar array[],Vec *vv)
    267: {
    269:   PetscDeviceInitialize(PETSC_DEVICE_HIP);
    270:   VecCreate(comm,vv);
    271:   VecSetSizes(*vv,n,N);
    272:   VecSetBlockSize(*vv,bs);
    273:   VecCreate_MPIHIP_Private(*vv,PETSC_FALSE,0,array);
    274:   return 0;
    275: }

    277: /*@C
    278:    VecCreateMPIHIPWithArrays - Creates a parallel, array-style vector,
    279:    where the user provides the GPU array space to store the vector values.

    281:    Collective

    283:    Input Parameters:
    284: +  comm  - the MPI communicator to use
    285: .  bs    - block size, same meaning as VecSetBlockSize()
    286: .  n     - local vector length, cannot be PETSC_DECIDE
    287: .  N     - global vector length (or PETSC_DECIDE to have calculated)
    288: -  cpuarray - the user provided CPU array to store the vector values
    289: -  gpuarray - the user provided GPU array to store the vector values

    291:    Output Parameter:
    292: .  vv - the vector

    294:    Notes:
    295:    If both cpuarray and gpuarray are provided, the caller must ensure that
    296:    the provided arrays have identical values.

    298:    Use VecDuplicate() or VecDuplicateVecs() to form additional vectors of the
    299:    same type as an existing vector.

    301:    PETSc does NOT free the provided arrays when the vector is destroyed via
    302:    VecDestroy(). The user should not free the array until the vector is
    303:    destroyed.

    305:    Level: intermediate

    307: .seealso: VecCreateSeqHIPWithArrays(), VecCreateMPIWithArray(), VecCreateSeqWithArray(),
    308:           VecCreate(), VecDuplicate(), VecDuplicateVecs(), VecCreateGhost(),
    309:           VecCreateMPI(), VecCreateGhostWithArray(), VecHIPPlaceArray(), VecPlaceArray(),
    310:           VecHIPAllocateCheckHost()
    311: @*/
    312: PetscErrorCode  VecCreateMPIHIPWithArrays(MPI_Comm comm,PetscInt bs,PetscInt n,PetscInt N,const PetscScalar cpuarray[],const PetscScalar gpuarray[],Vec *vv)
    313: {
    314:   VecCreateMPIHIPWithArray(comm,bs,n,N,gpuarray,vv);

    316:   if (cpuarray && gpuarray) {
    317:     Vec_MPI *s         = (Vec_MPI*)((*vv)->data);
    318:     s->array           = (PetscScalar*)cpuarray;
    319:     (*vv)->offloadmask = PETSC_OFFLOAD_BOTH;
    320:   } else if (cpuarray) {
    321:     Vec_MPI *s         = (Vec_MPI*)((*vv)->data);
    322:     s->array           = (PetscScalar*)cpuarray;
    323:     (*vv)->offloadmask =  PETSC_OFFLOAD_CPU;
    324:   } else if (gpuarray) {
    325:     (*vv)->offloadmask = PETSC_OFFLOAD_GPU;
    326:   } else {
    327:     (*vv)->offloadmask = PETSC_OFFLOAD_UNALLOCATED;
    328:   }

    330:   return 0;
    331: }

    333: PetscErrorCode VecMax_MPIHIP(Vec xin,PetscInt *idx,PetscReal *z)
    334: {
    335:   PetscReal      work;

    337:   VecMax_SeqHIP(xin,idx,&work);
    338: #if defined(PETSC_HAVE_MPIUNI)
    339:   *z = work;
    340: #else
    341:   if (!idx) {
    342:     MPIU_Allreduce(&work,z,1,MPIU_REAL,MPIU_MAX,PetscObjectComm((PetscObject)xin));
    343:   } else {
    344:     struct { PetscReal v; PetscInt i; } in,out;

    346:     in.v  = work;
    347:     in.i  = *idx + xin->map->rstart;
    348:     MPIU_Allreduce(&in,&out,1,MPIU_REAL_INT,MPIU_MAXLOC,PetscObjectComm((PetscObject)xin));
    349:     *z    = out.v;
    350:     *idx  = out.i;
    351:   }
    352: #endif
    353:   return 0;
    354: }

    356: PetscErrorCode VecMin_MPIHIP(Vec xin,PetscInt *idx,PetscReal *z)
    357: {
    358:   PetscReal      work;

    360:   VecMin_SeqHIP(xin,idx,&work);
    361: #if defined(PETSC_HAVE_MPIUNI)
    362:   *z = work;
    363: #else
    364:   if (!idx) {
    365:     MPIU_Allreduce(&work,z,1,MPIU_REAL,MPIU_MIN,PetscObjectComm((PetscObject)xin));
    366:   } else {
    367:     struct { PetscReal v; PetscInt i; } in,out;

    369:     in.v  = work;
    370:     in.i  = *idx + xin->map->rstart;
    371:     MPIU_Allreduce(&in,&out,1,MPIU_REAL_INT,MPIU_MINLOC,PetscObjectComm((PetscObject)xin));
    372:     *z    = out.v;
    373:     *idx  = out.i;
    374:   }
    375: #endif
    376:   return 0;
    377: }

    379: PetscErrorCode VecBindToCPU_MPIHIP(Vec V,PetscBool bind)
    380: {
    381:   V->boundtocpu = bind;
    382:   if (bind) {
    383:     VecHIPCopyFromGPU(V);
    384:     V->offloadmask = PETSC_OFFLOAD_CPU; /* since the CPU code will likely change values in the vector */
    385:     V->ops->dotnorm2               = NULL;
    386:     V->ops->waxpy                  = VecWAXPY_Seq;
    387:     V->ops->dot                    = VecDot_MPI;
    388:     V->ops->mdot                   = VecMDot_MPI;
    389:     V->ops->tdot                   = VecTDot_MPI;
    390:     V->ops->norm                   = VecNorm_MPI;
    391:     V->ops->scale                  = VecScale_Seq;
    392:     V->ops->copy                   = VecCopy_Seq;
    393:     V->ops->set                    = VecSet_Seq;
    394:     V->ops->swap                   = VecSwap_Seq;
    395:     V->ops->axpy                   = VecAXPY_Seq;
    396:     V->ops->axpby                  = VecAXPBY_Seq;
    397:     V->ops->maxpy                  = VecMAXPY_Seq;
    398:     V->ops->aypx                   = VecAYPX_Seq;
    399:     V->ops->axpbypcz               = VecAXPBYPCZ_Seq;
    400:     V->ops->pointwisemult          = VecPointwiseMult_Seq;
    401:     V->ops->setrandom              = VecSetRandom_Seq;
    402:     V->ops->placearray             = VecPlaceArray_Seq;
    403:     V->ops->replacearray           = VecReplaceArray_SeqHIP;
    404:     V->ops->resetarray             = VecResetArray_Seq;
    405:     V->ops->dot_local              = VecDot_Seq;
    406:     V->ops->tdot_local             = VecTDot_Seq;
    407:     V->ops->norm_local             = VecNorm_Seq;
    408:     V->ops->mdot_local             = VecMDot_Seq;
    409:     V->ops->pointwisedivide        = VecPointwiseDivide_Seq;
    410:     V->ops->getlocalvector         = NULL;
    411:     V->ops->restorelocalvector     = NULL;
    412:     V->ops->getlocalvectorread     = NULL;
    413:     V->ops->restorelocalvectorread = NULL;
    414:     V->ops->getarraywrite          = NULL;
    415:     V->ops->getarrayandmemtype     = NULL;
    416:     V->ops->restorearrayandmemtype = NULL;
    417:     V->ops->getarraywriteandmemtype= NULL;
    418:     V->ops->max                    = VecMax_MPI;
    419:     V->ops->min                    = VecMin_MPI;
    420:     V->ops->reciprocal             = VecReciprocal_Default;
    421:     V->ops->sum                    = NULL;
    422:     V->ops->shift                  = NULL;
    423:   } else {
    424:     V->ops->dotnorm2               = VecDotNorm2_MPIHIP;
    425:     V->ops->waxpy                  = VecWAXPY_SeqHIP;
    426:     V->ops->duplicate              = VecDuplicate_MPIHIP;
    427:     V->ops->dot                    = VecDot_MPIHIP;
    428:     V->ops->mdot                   = VecMDot_MPIHIP;
    429:     V->ops->tdot                   = VecTDot_MPIHIP;
    430:     V->ops->norm                   = VecNorm_MPIHIP;
    431:     V->ops->scale                  = VecScale_SeqHIP;
    432:     V->ops->copy                   = VecCopy_SeqHIP;
    433:     V->ops->set                    = VecSet_SeqHIP;
    434:     V->ops->swap                   = VecSwap_SeqHIP;
    435:     V->ops->axpy                   = VecAXPY_SeqHIP;
    436:     V->ops->axpby                  = VecAXPBY_SeqHIP;
    437:     V->ops->maxpy                  = VecMAXPY_SeqHIP;
    438:     V->ops->aypx                   = VecAYPX_SeqHIP;
    439:     V->ops->axpbypcz               = VecAXPBYPCZ_SeqHIP;
    440:     V->ops->pointwisemult          = VecPointwiseMult_SeqHIP;
    441:     V->ops->setrandom              = VecSetRandom_SeqHIP;
    442:     V->ops->placearray             = VecPlaceArray_SeqHIP;
    443:     V->ops->replacearray           = VecReplaceArray_SeqHIP;
    444:     V->ops->resetarray             = VecResetArray_SeqHIP;
    445:     V->ops->dot_local              = VecDot_SeqHIP;
    446:     V->ops->tdot_local             = VecTDot_SeqHIP;
    447:     V->ops->norm_local             = VecNorm_SeqHIP;
    448:     V->ops->mdot_local             = VecMDot_SeqHIP;
    449:     V->ops->destroy                = VecDestroy_MPIHIP;
    450:     V->ops->pointwisedivide        = VecPointwiseDivide_SeqHIP;
    451:     V->ops->getlocalvector         = VecGetLocalVector_SeqHIP;
    452:     V->ops->restorelocalvector     = VecRestoreLocalVector_SeqHIP;
    453:     V->ops->getlocalvectorread     = VecGetLocalVectorRead_SeqHIP;
    454:     V->ops->restorelocalvectorread = VecRestoreLocalVectorRead_SeqHIP;
    455:     V->ops->getarraywrite          = VecGetArrayWrite_SeqHIP;
    456:     V->ops->getarray               = VecGetArray_SeqHIP;
    457:     V->ops->restorearray           = VecRestoreArray_SeqHIP;
    458:     V->ops->getarrayandmemtype     = VecGetArrayAndMemType_SeqHIP;
    459:     V->ops->restorearrayandmemtype = VecRestoreArrayAndMemType_SeqHIP;
    460:     V->ops->getarraywriteandmemtype= VecGetArrayWriteAndMemType_SeqHIP;
    461:     V->ops->max                    = VecMax_MPIHIP;
    462:     V->ops->min                    = VecMin_MPIHIP;
    463:     V->ops->reciprocal             = VecReciprocal_SeqHIP;
    464:     V->ops->sum                    = VecSum_SeqHIP;
    465:     V->ops->shift                  = VecShift_SeqHIP;
    466:   }
    467:   return 0;
    468: }

    470: PetscErrorCode VecCreate_MPIHIP_Private(Vec vv,PetscBool alloc,PetscInt nghost,const PetscScalar array[])
    471: {
    472:   Vec_HIP *vechip;

    474:   VecCreate_MPI_Private(vv,PETSC_FALSE,0,0);
    475:   PetscObjectChangeTypeName((PetscObject)vv,VECMPIHIP);

    477:   VecBindToCPU_MPIHIP(vv,PETSC_FALSE);
    478:   vv->ops->bindtocpu = VecBindToCPU_MPIHIP;

    480:   /* Later, functions check for the Vec_HIP structure existence, so do not create it without array */
    481:   if (alloc && !array) {
    482:     VecHIPAllocateCheck(vv);
    483:     VecHIPAllocateCheckHost(vv);
    484:     VecSet(vv,0.0);
    485:     VecSet_Seq(vv,0.0);
    486:     vv->offloadmask = PETSC_OFFLOAD_BOTH;
    487:   }
    488:   if (array) {
    489:     if (!vv->spptr) {
    490:       PetscReal      pinned_memory_min;
    491:       PetscBool      flag;

    494:       /* Cannot use PetscNew() here because spptr is void* */
    495:       PetscCalloc(sizeof(Vec_HIP),&vv->spptr);
    496:       vechip = (Vec_HIP*)vv->spptr;
    497:       vv->minimum_bytes_pinned_memory = 0;

    499:       /* Need to parse command line for minimum size to use for pinned memory allocations on host here.
    500:          Note: This same code duplicated in VecCreate_SeqHIP_Private() and VecHIPAllocateCheck(). Is there a good way to avoid this? */
    501:       PetscOptionsBegin(PetscObjectComm((PetscObject)vv),((PetscObject)vv)->prefix,"VECHIP Options","Vec");
    502:       pinned_memory_min = vv->minimum_bytes_pinned_memory;
    503:       PetscOptionsReal("-vec_pinned_memory_min","Minimum size (in bytes) for an allocation to use pinned memory on host","VecSetPinnedMemoryMin",pinned_memory_min,&pinned_memory_min,&flag);
    504:       if (flag) vv->minimum_bytes_pinned_memory = pinned_memory_min;
    505:       PetscOptionsEnd();
    506:     }
    507:     vechip = (Vec_HIP*)vv->spptr;
    508:     vechip->GPUarray = (PetscScalar*)array;
    509:     vv->offloadmask = PETSC_OFFLOAD_GPU;
    510:   }
    511:   return 0;
    512: }