Actual source code: pipegcr.c
petsc-3.7.1 2016-05-15
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      1: /*
      2:     Contributed by Sascha M. Schnepp and Patrick Sanan
      3: */

     5:  #include petscsys.h
      6: #include <../src/ksp/ksp/impls/gcr/pipegcr/pipegcrimpl.h>       /*I  "petscksp.h"  I*/

      8: #define KSPPIPEGCR_DEFAULT_MMAX 15
      9: #define KSPPIPEGCR_DEFAULT_NPREALLOC 5
     10: #define KSPPIPEGCR_DEFAULT_VECB 5
     11: #define KSPPIPEGCR_DEFAULT_TRUNCSTRAT KSP_FCD_TRUNC_TYPE_NOTAY
     12: #define KSPPIPEGCR_DEFAULT_UNROLL_W PETSC_TRUE

     14: #include <petscksp.h>

     18: static PetscErrorCode KSPAllocateVectors_PIPEGCR(KSP ksp, PetscInt nvecsneeded, PetscInt chunksize)
     19: {
     20:   PetscErrorCode  ierr;
     21:   PetscInt        i;
     22:   KSP_PIPEGCR     *pipegcr;
     23:   PetscInt        nnewvecs, nvecsprev;

     26:   pipegcr = (KSP_PIPEGCR*)ksp->data;

     28:   /* Allocate enough new vectors to add chunksize new vectors, reach nvecsneedtotal, or to reach mmax+1, whichever is smallest */
     29:   if(pipegcr->nvecs < PetscMin(pipegcr->mmax+1,nvecsneeded)){
     30:     nvecsprev = pipegcr->nvecs;
     31:     nnewvecs = PetscMin(PetscMax(nvecsneeded-pipegcr->nvecs,chunksize),pipegcr->mmax+1-pipegcr->nvecs);
     32:     KSPCreateVecs(ksp,nnewvecs,&pipegcr->ppvecs[pipegcr->nchunks],0,NULL);
     33:     PetscLogObjectParents((PetscObject)ksp,nnewvecs,pipegcr->ppvecs[pipegcr->nchunks]);
     34:     KSPCreateVecs(ksp,nnewvecs,&pipegcr->psvecs[pipegcr->nchunks],0,NULL);
     35:     PetscLogObjectParents((PetscObject)ksp,nnewvecs,pipegcr->psvecs[pipegcr->nchunks]);
     36:     KSPCreateVecs(ksp,nnewvecs,&pipegcr->pqvecs[pipegcr->nchunks],0,NULL);
     37:     PetscLogObjectParents((PetscObject)ksp,nnewvecs,pipegcr->pqvecs[pipegcr->nchunks]);
     38:     if (pipegcr->unroll_w) {
     39:       KSPCreateVecs(ksp,nnewvecs,&pipegcr->ptvecs[pipegcr->nchunks],0,NULL);
     40:       PetscLogObjectParents((PetscObject)ksp,nnewvecs,pipegcr->ptvecs[pipegcr->nchunks]);
     41:     }
     42:     pipegcr->nvecs += nnewvecs;
     43:     for(i=0;i<nnewvecs;i++){
     44:       pipegcr->qvecs[nvecsprev+i] = pipegcr->pqvecs[pipegcr->nchunks][i];
     45:       pipegcr->pvecs[nvecsprev+i] = pipegcr->ppvecs[pipegcr->nchunks][i];
     46:       pipegcr->svecs[nvecsprev+i] = pipegcr->psvecs[pipegcr->nchunks][i];
     47:       if (pipegcr->unroll_w) {
     48:         pipegcr->tvecs[nvecsprev+i] = pipegcr->ptvecs[pipegcr->nchunks][i];
     49:       }
     50:     }
     51:     pipegcr->chunksizes[pipegcr->nchunks] = nnewvecs;
     52:     pipegcr->nchunks++;
     53:   }
     54:   return(0);
     55: }

     59: PetscErrorCode KSPSolve_PIPEGCR_cycle(KSP ksp)
     60: {
     61:   KSP_PIPEGCR    *pipegcr = (KSP_PIPEGCR*)ksp->data;
     63:   Mat            A, B;
     64:   Vec            x,r,b,z,w,m,n,p,s,q,t,*redux;
     65:   PetscInt       i,j,k,idx,kdx,mi;
     66:   PetscScalar    alpha=0.0,gamma,*betas,*dots;
     67:   PetscReal      rnorm=0.0, delta,*eta,*etas;

     71:   /* !!PS We have not checked these routines for use with complex numbers. The inner products
     72:      are likely not defined correctly for that case */
     73: #if (defined(PETSC_USE_COMPLEX) && !defined(PETSC_SKIP_COMPLEX))
     74:   SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP,"PIPEGCR has not been implemented for use with complex scalars");
     75: #endif

     77:   KSPGetOperators(ksp, &A, &B);
     78:   x = ksp->vec_sol;
     79:   b = ksp->vec_rhs;
     80:   r = ksp->work[0];
     81:   z = ksp->work[1];
     82:   w = ksp->work[2]; /* w = Az = AB(r)                 (pipelining intermediate) */
     83:   m = ksp->work[3]; /* m = B(w) = B(Az) = B(AB(r))    (pipelining intermediate) */
     84:   n = ksp->work[4]; /* n = AB(w) = AB(Az) = AB(AB(r)) (pipelining intermediate) */
     85:   p = pipegcr->pvecs[0];
     86:   s = pipegcr->svecs[0];
     87:   q = pipegcr->qvecs[0];
     88:   t = pipegcr->unroll_w ? pipegcr->tvecs[0] : NULL;

     90:   redux = pipegcr->redux;
     91:   dots  = pipegcr->dots;
     92:   etas  = pipegcr->etas;
     93:   betas = dots;        /* dots takes the result of all dot products of which the betas are a subset */

     95:   /* cycle initial residual */
     96:   KSP_MatMult(ksp,A,x,r);
     97:   VecAYPX(r,-1.0,b);                   /* r <- b - Ax */
     98:   KSP_PCApply(ksp,r,z);                /* z <- B(r)   */
     99:   KSP_MatMult(ksp,A,z,w);              /* w <- Az     */

    101:   /* initialization of other variables and pipelining intermediates */
    102:   VecCopy(z,p);
    103:   KSP_MatMult(ksp,A,p,s);

    105:   /* overlap initial computation of delta, gamma */
    106:   redux[0] = w;
    107:   redux[1] = r;
    108:   VecMDotBegin(w,2,redux,dots);    /* Start split reductions for gamma = (w,r), delta = (w,w) */
    109:   PetscCommSplitReductionBegin(PetscObjectComm((PetscObject)s)); /* perform asynchronous reduction */
    110:   KSP_PCApply(ksp,s,q);            /* q = B(s) */
    111:   if (pipegcr->unroll_w) {
    112:     KSP_MatMult(ksp,A,q,t);        /* t = Aq   */
    113:   }
    114:   VecMDotEnd(w,2,redux,dots);      /* Finish split reduction */
    115:   delta    = PetscRealPart(dots[0]);
    116:   etas[0]  = delta;
    117:   gamma    = dots[1];
    118:   alpha    = gamma/delta;

    120:   i = 0;
    121:   do {
    122:     PetscObjectSAWsTakeAccess((PetscObject)ksp);
    123:     ksp->its++;
    124:     PetscObjectSAWsGrantAccess((PetscObject)ksp);

    126:     /* update solution, residuals, .. */
    127:     VecAXPY(x,+alpha,p);
    128:     VecAXPY(r,-alpha,s);
    129:     VecAXPY(z,-alpha,q);
    130:     if(pipegcr->unroll_w){
    131:       VecAXPY(w,-alpha,t);
    132:     } else {
    133:       KSP_MatMult(ksp,A,z,w);
    134:     }

    136:     /* Computations of current iteration done */
    137:     i++;

    139:     if (pipegcr->modifypc) {
    140:       (*pipegcr->modifypc)(ksp,ksp->its,ksp->rnorm,pipegcr->modifypc_ctx);
    141:     }

    143:     /* If needbe, allocate a new chunk of vectors */
    144:     KSPAllocateVectors_PIPEGCR(ksp,i+1,pipegcr->vecb);

    146:     /* Note that we wrap around and start clobbering old vectors */
    147:     idx = i % (pipegcr->mmax+1);
    148:     p   = pipegcr->pvecs[idx];
    149:     s   = pipegcr->svecs[idx];
    150:     q   = pipegcr->qvecs[idx];
    151:     if (pipegcr->unroll_w) {
    152:       t   = pipegcr->tvecs[idx];
    153:     }
    154:     eta = pipegcr->etas+idx;

    156:     /* number of old directions to orthogonalize against */
    157:     switch(pipegcr->truncstrat){
    158:       case KSP_FCD_TRUNC_TYPE_STANDARD:
    159:         mi = pipegcr->mmax;
    160:         break;
    161:       case KSP_FCD_TRUNC_TYPE_NOTAY:
    162:         mi = ((i-1) % pipegcr->mmax)+1;
    163:         break;
    164:       default:
    165:         SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Unrecognized Truncation Strategy");
    166:     }

    168:     /* Pick old p,s,q,zeta in a way suitable for VecMDot */
    169:     for(k=PetscMax(0,i-mi),j=0;k<i;j++,k++){
    170:       kdx = k % (pipegcr->mmax+1);
    171:       pipegcr->pold[j] = pipegcr->pvecs[kdx];
    172:       pipegcr->sold[j] = pipegcr->svecs[kdx];
    173:       pipegcr->qold[j] = pipegcr->qvecs[kdx];
    174:       if (pipegcr->unroll_w) {
    175:         pipegcr->told[j] = pipegcr->tvecs[kdx];
    176:       }
    177:       redux[j]         = pipegcr->svecs[kdx];
    178:     }
    179:     /* If the above loop is not run redux contains only r and w => all beta_k = 0, only gamma, delta != 0 */
    180:     redux[j]   = r;
    181:     redux[j+1] = w;

    183:     /* Dot products */
    184:     /* Start split reductions for beta_k = (w,s_k), gamma = (w,r), delta = (w,w) */
    185:     VecMDotBegin(w,j+2,redux,dots);
    186:     PetscCommSplitReductionBegin(PetscObjectComm((PetscObject)w));

    188:     /* B(w-r) + u stabilization */
    189:     VecWAXPY(n,-1.0,r,w);              /* m = u + B(w-r): (a) ntmp = w-r              */
    190:     KSP_PCApply(ksp,n,m);              /* m = u + B(w-r): (b) mtmp = B(ntmp) = B(w-r) */
    191:     VecAXPY(m,1.0,z);                  /* m = u + B(w-r): (c) m = z + mtmp            */
    192:     if(pipegcr->unroll_w){
    193:       KSP_MatMult(ksp,A,m,n);          /* n = Am                                      */
    194:     }

    196:     /* Finish split reductions for beta_k = (w,s_k), gamma = (w,r), delta = (w,w) */
    197:     VecMDotEnd(w,j+2,redux,dots);
    198:     gamma = dots[j];
    199:     delta = PetscRealPart(dots[j+1]);

    201:     /* compute new residual norm.
    202:        this cannot be done before this point so that the natural norm
    203:        is available for free and the communication involved is overlapped */
    204:     switch (ksp->normtype) {
    205:     case KSP_NORM_PRECONDITIONED:
    206:       VecNorm(z,NORM_2,&rnorm);        /* ||r|| <- sqrt(z'*z) */
    207:       break;
    208:     case KSP_NORM_UNPRECONDITIONED:
    209:       VecNorm(r,NORM_2,&rnorm);        /* ||r|| <- sqrt(r'*r) */
    210:       break;
    211:     case KSP_NORM_NATURAL:
    212:       rnorm = PetscSqrtReal(PetscAbsScalar(gamma));         /* ||r|| <- sqrt(r,w)  */
    213:       break;
    214:     case KSP_NORM_NONE:
    215:       rnorm = 0.0;
    216:       break;
    217:     default: SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"%s",KSPNormTypes[ksp->normtype]);
    218:     }

    220:     /* Check for convergence */
    221:     PetscObjectSAWsTakeAccess((PetscObject)ksp);
    222:     ksp->rnorm = rnorm;
    223:     PetscObjectSAWsGrantAccess((PetscObject)ksp);
    224:     KSPLogResidualHistory(ksp,rnorm);
    225:     KSPMonitor(ksp,ksp->its,rnorm);
    226:     (*ksp->converged)(ksp,ksp->its+1,rnorm,&ksp->reason,ksp->cnvP);
    227:     if (ksp->reason) break;

    229:     /* compute new eta and scale beta */
    230:     *eta = 0.;
    231:     for(k=PetscMax(0,i-mi),j=0;k<i;j++,k++){
    232:       kdx = k % (pipegcr->mmax+1);
    233:       betas[j] /= -etas[kdx];                               /* betak  /= etak */
    234:       *eta -= ((PetscReal)(PetscAbsScalar(betas[j])*PetscAbsScalar(betas[j]))) * etas[kdx];
    235:                                                             /* etaitmp = -betaik^2 * etak */
    236:     }
    237:     *eta += delta;                                          /* etai    = delta -betaik^2 * etak */

    239:     /* check breakdown of eta = (s,s) */
    240:     if(*eta < 0.) {
    241:       pipegcr->norm_breakdown = PETSC_TRUE;
    242:       PetscInfo1(ksp,"Restart due to square root breakdown at it = \n",ksp->its);
    243:       break;
    244:     } else {
    245:       alpha= gamma/(*eta);                                  /* alpha = gamma/etai */
    246:     }

    248:     /* project out stored search directions using classical G-S */
    249:     VecCopy(z,p);
    250:     VecCopy(w,s);
    251:     VecCopy(m,q);
    252:     if(pipegcr->unroll_w){
    253:       VecCopy(n,t);
    254:       VecMAXPY(t,j,betas,pipegcr->told); /* ti <- n  - sum_k beta_k t_k */
    255:     }
    256:     VecMAXPY(p,j,betas,pipegcr->pold); /* pi <- ui - sum_k beta_k p_k */
    257:     VecMAXPY(s,j,betas,pipegcr->sold); /* si <- wi - sum_k beta_k s_k */
    258:     VecMAXPY(q,j,betas,pipegcr->qold); /* qi <- m  - sum_k beta_k q_k */

    260:   } while (ksp->its < ksp->max_it);
    261:   return(0);
    262: }

    266: PetscErrorCode KSPSolve_PIPEGCR(KSP ksp)
    267: {
    268:   KSP_PIPEGCR    *pipegcr = (KSP_PIPEGCR*)ksp->data;
    270:   Mat            A, B;
    271:   Vec            x,b,r,z,w;
    272:   PetscScalar    gamma;
    273:   PetscReal      rnorm=0.0;
    274:   PetscBool      issym;

    277:   KSPGetOperators(ksp, &A, &B);
    278:   x = ksp->vec_sol;
    279:   b = ksp->vec_rhs;
    280:   r = ksp->work[0];
    281:   z = ksp->work[1];
    282:   w = ksp->work[2]; /* w = Az = AB(r)                 (pipelining intermediate) */

    284:   /* compute initial residual */
    285:   if (!ksp->guess_zero) {
    286:     KSP_MatMult(ksp,A,x,r);
    287:     VecAYPX(r,-1.0,b);                 /* r <- b - Ax       */
    288:   } else {
    289:     VecCopy(b,r);                      /* r <- b            */
    290:   }

    292:   /* initial residual norm */
    293:   KSP_PCApply(ksp,r,z);                /* z <- B(r)         */
    294:   KSP_MatMult(ksp,A,z,w);              /* w <- Az           */
    295:   VecDot(r,w,&gamma);                  /* gamma = (r,w)     */

    297:   switch (ksp->normtype) {
    298:     case KSP_NORM_PRECONDITIONED:
    299:       VecNorm(z,NORM_2,&rnorm);        /* ||r|| <- sqrt(z'*z) */
    300:       break;
    301:     case KSP_NORM_UNPRECONDITIONED:
    302:       VecNorm(r,NORM_2,&rnorm);        /* ||r|| <- sqrt(r'*r) */
    303:       break;
    304:     case KSP_NORM_NATURAL:
    305:       rnorm = PetscSqrtReal(PetscAbsScalar(gamma));         /* ||r|| <- sqrt(r,w)  */
    306:       break;
    307:     case KSP_NORM_NONE:
    308:       rnorm = 0.0;
    309:       break;
    310:     default: SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"%s",KSPNormTypes[ksp->normtype]);
    311:   }

    313:   /* Is A symmetric? */
    314:   PetscObjectTypeCompareAny((PetscObject)A,&issym,"sbaij","seqsbaij","mpibaij","");
    315:   if (!issym) {
    316:     PetscInfo(A,"Matrix type is not any of MATSBAIJ,MATSEQSBAIJ,MATMPIBAIJ. Is matrix A symmetric (as required by CR methods)?");
    317:   }

    319:   /* logging */
    320:   PetscObjectSAWsTakeAccess((PetscObject)ksp);
    321:   ksp->its    = 0;
    322:   ksp->rnorm0 = rnorm;
    323:   PetscObjectSAWsGrantAccess((PetscObject)ksp);
    324:   KSPLogResidualHistory(ksp,ksp->rnorm0);
    325:   KSPMonitor(ksp,ksp->its,ksp->rnorm0);
    326:   (*ksp->converged)(ksp,ksp->its,ksp->rnorm0,&ksp->reason,ksp->cnvP);
    327:   if (ksp->reason) return(0);

    329:   do {
    330:     KSPSolve_PIPEGCR_cycle(ksp);
    331:     if (ksp->reason) break;
    332:     if (pipegcr->norm_breakdown) {
    333:       pipegcr->n_restarts++;
    334:       pipegcr->norm_breakdown = PETSC_FALSE;
    335:     }
    336:   } while (ksp->its < ksp->max_it);

    338:   if (ksp->its >= ksp->max_it) ksp->reason = KSP_DIVERGED_ITS;
    339:   return(0);
    340: }

    344: PetscErrorCode KSPView_PIPEGCR(KSP ksp, PetscViewer viewer)
    345: {
    346:   KSP_PIPEGCR    *pipegcr = (KSP_PIPEGCR*)ksp->data;
    348:   PetscBool      isascii,isstring;
    349:   const char     *truncstr;

    352:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII, &isascii);
    353:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);

    355:   if(pipegcr->truncstrat == KSP_FCD_TRUNC_TYPE_STANDARD){
    356:     truncstr = "Using standard truncation strategy";
    357:   } else if(pipegcr->truncstrat == KSP_FCD_TRUNC_TYPE_NOTAY){
    358:     truncstr = "Using Notay's truncation strategy";
    359:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Undefined FCD truncation strategy");
    360:

    362:   if (isascii) {
    363:     PetscViewerASCIIPrintf(viewer,"  PIPEGCR: max previous directions = %D\n",pipegcr->mmax);
    364:     PetscViewerASCIIPrintf(viewer,"  PIPEGCR: preallocated %D directions\n",PetscMin(pipegcr->nprealloc,pipegcr->mmax+1));
    365:     PetscViewerASCIIPrintf(viewer,"  PIPEGCR: %s\n",truncstr);
    366:     PetscViewerASCIIPrintf(viewer,"  PIPEGCR: w unrolling = %D \n", pipegcr->unroll_w);
    367:     PetscViewerASCIIPrintf(viewer,"  PIPEGCR: restarts performed = %D \n", pipegcr->n_restarts);
    368:   } else if (isstring) {
    369:     PetscViewerStringSPrintf(viewer, "max previous directions = %D, preallocated %D directions, %s truncation strategy", pipegcr->mmax,pipegcr->nprealloc,truncstr);
    370:   }
    371:   return(0);
    372: }

    377: PetscErrorCode KSPSetUp_PIPEGCR(KSP ksp)
    378: {
    379:   KSP_PIPEGCR   *pipegcr = (KSP_PIPEGCR*)ksp->data;
    381:   Mat            A;
    382:   PetscBool      diagonalscale;
    383:   const PetscInt nworkstd = 5;

    386:   PCGetDiagonalScale(ksp->pc,&diagonalscale);
    387:   if (diagonalscale) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"Krylov method %s does not support diagonal scaling",((PetscObject)ksp)->type_name);

    389:   KSPGetOperators(ksp, &A, NULL);

    391:   /* Allocate "standard" work vectors */
    392:   KSPSetWorkVecs(ksp,nworkstd);

    394:   /* Allocated space for pointers to additional work vectors
    395:     note that mmax is the number of previous directions, so we add 1 for the current direction */
    396:   PetscMalloc6(pipegcr->mmax+1,&(pipegcr->pvecs),pipegcr->mmax+1,&(pipegcr->ppvecs),pipegcr->mmax+1,&(pipegcr->svecs), pipegcr->mmax+1,&(pipegcr->psvecs),pipegcr->mmax+1,&(pipegcr->qvecs),pipegcr->mmax+1,&(pipegcr->pqvecs));
    397:   if (pipegcr->unroll_w) {
    398:     PetscMalloc3(pipegcr->mmax+1,&(pipegcr->tvecs),pipegcr->mmax+1,&(pipegcr->ptvecs),pipegcr->mmax+2,&(pipegcr->told));
    399:   }
    400:   PetscMalloc4(pipegcr->mmax+2,&(pipegcr->pold),pipegcr->mmax+2,&(pipegcr->sold),pipegcr->mmax+2,&(pipegcr->qold),pipegcr->mmax+2,&(pipegcr->chunksizes));
    401:   PetscMalloc3(pipegcr->mmax+2,&(pipegcr->dots),pipegcr->mmax+1,&(pipegcr->etas),pipegcr->mmax+2,&(pipegcr->redux));
    402:   /* If the requested number of preallocated vectors is greater than mmax reduce nprealloc */
    403:   if(pipegcr->nprealloc > pipegcr->mmax+1){
    404:     PetscInfo2(NULL,"Requested nprealloc=%d is greater than m_max+1=%d. Resetting nprealloc = m_max+1.\n",pipegcr->nprealloc, pipegcr->mmax+1);
    405:   }

    407:   /* Preallocate additional work vectors */
    408:   KSPAllocateVectors_PIPEGCR(ksp,pipegcr->nprealloc,pipegcr->nprealloc);

    410:   PetscLogObjectMemory(
    411:     (PetscObject)ksp,
    412:     (pipegcr->mmax + 1) * 4 * sizeof(Vec*) +        /* old dirs  */
    413:     (pipegcr->mmax + 1) * 4 * sizeof(Vec**) +       /* old pdirs */
    414:     (pipegcr->mmax + 1) * 4 * sizeof(Vec*) +        /* p/s/qold/told */
    415:     (pipegcr->mmax + 1) *     sizeof(PetscInt) +    /* chunksizes */
    416:     (pipegcr->mmax + 2) *     sizeof(Vec*) +        /* redux */
    417:     (pipegcr->mmax + 2) *     sizeof(PetscScalar) + /* dots */
    418:     (pipegcr->mmax + 1) *     sizeof(PetscReal)     /* etas */
    419:   );
    420:   return(0);
    421: }

    425: PetscErrorCode KSPReset_PIPEGCR(KSP ksp)
    426: {
    428:   KSP_PIPEGCR    *pipegcr = (KSP_PIPEGCR*)ksp->data;

    431:   if (pipegcr->modifypc_destroy) {
    432:     (*pipegcr->modifypc_destroy)(pipegcr->modifypc_ctx);
    433:   }
    434:   return(0);
    435: }

    439: PetscErrorCode KSPDestroy_PIPEGCR(KSP ksp)
    440: {
    442:   PetscInt       i;
    443:   KSP_PIPEGCR    *pipegcr = (KSP_PIPEGCR*)ksp->data;

    446:   VecDestroyVecs(ksp->nwork,&ksp->work); /* Destroy "standard" work vecs */

    448:   /* Destroy vectors for old directions and the arrays that manage pointers to them */
    449:   if(pipegcr->nvecs){
    450:     for(i=0;i<pipegcr->nchunks;i++){
    451:       VecDestroyVecs(pipegcr->chunksizes[i],&pipegcr->ppvecs[i]);
    452:       VecDestroyVecs(pipegcr->chunksizes[i],&pipegcr->psvecs[i]);
    453:       VecDestroyVecs(pipegcr->chunksizes[i],&pipegcr->pqvecs[i]);
    454:       if (pipegcr->unroll_w) {
    455:         VecDestroyVecs(pipegcr->chunksizes[i],&pipegcr->ptvecs[i]);
    456:       }
    457:     }
    458:   }

    460:   PetscFree6(pipegcr->pvecs,pipegcr->ppvecs,pipegcr->svecs,pipegcr->psvecs,pipegcr->qvecs,pipegcr->pqvecs);
    461:   PetscFree4(pipegcr->pold,pipegcr->sold,pipegcr->qold,pipegcr->chunksizes);
    462:   PetscFree3(pipegcr->dots,pipegcr->etas,pipegcr->redux);
    463:   if (pipegcr->unroll_w) {
    464:     PetscFree3(pipegcr->tvecs,pipegcr->ptvecs,pipegcr->told);
    465:   }

    467:   KSPReset_PIPEGCR(ksp);
    468:   KSPDestroyDefault(ksp);
    469:   return(0);
    470: }

    474: /*@
    475:   KSPPIPEGCRSetUnrollW - Set to PETSC_TRUE to use PIPEGCR with unrolling of the w vector

    477:   Logically Collective on KSP

    479:   Input Parameters:
    480: +  ksp - the Krylov space context
    481: -  unroll_w - use unrolling

    483:   Level: intermediate

    485:   Options Database:
    486: . -ksp_pipegcr_unroll_w

    488: .seealso: KSPPIPEGCR, KSPPIPEGCRSetTruncationType(), KSPPIPEGCRSetNprealloc(),KSPPIPEGCRGetUnrollW()
    489: @*/
    490: PetscErrorCode KSPPIPEGCRSetUnrollW(KSP ksp,PetscBool unroll_w)
    491: {
    492:   KSP_PIPEGCR *pipegcr=(KSP_PIPEGCR*)ksp->data;;

    497:   pipegcr->unroll_w=unroll_w;
    498:   return(0);
    499: }

    503: /*@
    504:   KSPPIPEGCRGetUnrollW - Get information on PIPEGCR unrolling the w vector

    506:   Logically Collective on KSP

    508:    Input Parameter:
    509: .  ksp - the Krylov space context

    511:    Output Parameter:
    512: .  unroll_w - PIPEGCR uses unrolling (bool)

    514:   Level: intermediate

    516:   Options Database:
    517: . -ksp_pipegcr_unroll_w

    519: .seealso: KSPPIPEGCR, KSPPIPEGCRGetTruncationType(), KSPPIPEGCRGetNprealloc(),KSPPIPEGCRSetUnrollW()
    520: @*/
    521: PetscErrorCode KSPPIPEGCRGetUnrollW(KSP ksp,PetscBool *unroll_w)
    522: {
    523:   KSP_PIPEGCR *pipegcr=(KSP_PIPEGCR*)ksp->data;;

    527:   *unroll_w=pipegcr->unroll_w;
    528:   return(0);
    529: }

    533: /*@
    534:   KSPPIPEGCRSetMmax - set the maximum number of previous directions PIPEGCR will store for orthogonalization

    536:   Note: mmax + 1 directions are stored (mmax previous ones along with a current one)
    537:   and whether all are used in each iteration also depends on the truncation strategy
    538:   (see KSPPIPEGCRSetTruncationType)

    540:   Logically Collective on KSP

    542:   Input Parameters:
    543: +  ksp - the Krylov space context
    544: -  mmax - the maximum number of previous directions to orthogonalize againt

    546:   Level: intermediate

    548:   Options Database:
    549: . -ksp_pipegcr_mmax <N>

    551: .seealso: KSPPIPEGCR, KSPPIPEGCRSetTruncationType(), KSPPIPEGCRSetNprealloc()
    552: @*/
    553: PetscErrorCode KSPPIPEGCRSetMmax(KSP ksp,PetscInt mmax)
    554: {
    555:   KSP_PIPEGCR *pipegcr=(KSP_PIPEGCR*)ksp->data;;

    560:   pipegcr->mmax=mmax;
    561:   return(0);
    562: }

    566: /*@
    567:   KSPPIPEGCRGetMmax - get the maximum number of previous directions PIPEGCR will store

    569:   Note: PIPEGCR stores mmax+1 directions at most (mmax previous ones, and one current one)

    571:    Not Collective

    573:    Input Parameter:
    574: .  ksp - the Krylov space context

    576:    Output Parameter:
    577: .  mmax - the maximum number of previous directons allowed for orthogonalization

    579:   Options Database:
    580: . -ksp_pipegcr_mmax <N>

    582:    Level: intermediate

    584: .keywords: KSP, PIPEGCR, truncation

    586: .seealso: KSPPIPEGCR, KSPPIPEGCRGetTruncationType(), KSPPIPEGCRGetNprealloc(), KSPPIPEGCRSetMmax()
    587: @*/

    589: PetscErrorCode KSPPIPEGCRGetMmax(KSP ksp,PetscInt *mmax)
    590: {
    591:   KSP_PIPEGCR *pipegcr=(KSP_PIPEGCR*)ksp->data;;

    595:   *mmax=pipegcr->mmax;
    596:   return(0);
    597: }

    601: /*@
    602:   KSPPIPEGCRSetNprealloc - set the number of directions to preallocate with PIPEGCR

    604:   Logically Collective on KSP

    606:   Input Parameters:
    607: +  ksp - the Krylov space context
    608: -  nprealloc - the number of vectors to preallocate

    610:   Level: advanced

    612:   Options Database:
    613: . -ksp_pipegcr_nprealloc <N>

    615: .seealso: KSPPIPEGCR, KSPPIPEGCRGetTruncationType(), KSPPIPEGCRGetNprealloc()
    616: @*/
    617: PetscErrorCode KSPPIPEGCRSetNprealloc(KSP ksp,PetscInt nprealloc)
    618: {
    619:   KSP_PIPEGCR *pipegcr=(KSP_PIPEGCR*)ksp->data;;

    624:   pipegcr->nprealloc = nprealloc;
    625:   return(0);
    626: }

    630: /*@
    631:   KSPPIPEGCRGetNprealloc - get the number of directions preallocate by PIPEGCR

    633:    Not Collective

    635:    Input Parameter:
    636: .  ksp - the Krylov space context

    638:    Output Parameter:
    639: .  nprealloc - the number of directions preallocated

    641:   Options Database:
    642: . -ksp_pipegcr_nprealloc <N>

    644:    Level: advanced

    646: .keywords: KSP, PIPEGCR, truncation

    648: .seealso: KSPPIPEGCR, KSPPIPEGCRGetTruncationType(), KSPPIPEGCRSetNprealloc()
    649: @*/
    650: PetscErrorCode KSPPIPEGCRGetNprealloc(KSP ksp,PetscInt *nprealloc)
    651: {
    652:   KSP_PIPEGCR *pipegcr=(KSP_PIPEGCR*)ksp->data;;

    656:   *nprealloc = pipegcr->nprealloc;
    657:   return(0);
    658: }

    662: /*@
    663:   KSPPIPEGCRSetTruncationType - specify how many of its stored previous directions PIPEGCR uses during orthoganalization

    665:   Logically Collective on KSP

    667:   KSP_FCD_TRUNC_TYPE_STANDARD uses all (up to mmax) stored directions
    668:   KSP_FCD_TRUNC_TYPE_NOTAY uses the last max(1,mod(i,mmax)) directions at iteration i=0,1,..

    670:   Input Parameters:
    671: +  ksp - the Krylov space context
    672: -  truncstrat - the choice of strategy

    674:   Level: intermediate

    676:   Options Database:
    677: . -ksp_pipegcr_truncation, -ksp_pipegcr_truncation_restart

    679: .seealso: KSPPIPEGCR, KSPPIPEGCRSetTruncationType, KSPPIPEGCRTruncationType, KSPFCDTruncationType
    680: @*/
    681: PetscErrorCode KSPPIPEGCRSetTruncationType(KSP ksp,KSPFCDTruncationType truncstrat)
    682: {
    683:   KSP_PIPEGCR *pipegcr=(KSP_PIPEGCR*)ksp->data;;

    688:   pipegcr->truncstrat=truncstrat;
    689:   return(0);
    690: }

    694: /*@
    695:   KSPPIPEGCRGetTruncationType - get the truncation strategy employed by PIPEGCR

    697:   Not Collective

    699:   KSP_FCD_TRUNC_TYPE_STANDARD uses all (up to mmax) stored directions
    700:   KSP_FCD_TRUNC_TYPE_NOTAY uses the last max(1,mod(i,mmax)) directions at iteration i=0,1,..

    702:    Input Parameter:
    703: .  ksp - the Krylov space context

    705:    Output Parameter:
    706: .  truncstrat - the strategy type

    708:   Options Database:
    709: . -ksp_pipegcr_truncation, -ksp_pipegcr_truncation_restart

    711:    Level: intermediate

    713: .keywords: KSP, PIPEGCR, truncation

    715: .seealso: KSPPIPEGCR, KSPPIPEGCRSetTruncationType, KSPPIPEGCRTruncationType, KSPFCDTruncationType
    716: @*/
    717: PetscErrorCode KSPPIPEGCRGetTruncationType(KSP ksp,KSPFCDTruncationType *truncstrat)
    718: {
    719:   KSP_PIPEGCR *pipegcr=(KSP_PIPEGCR*)ksp->data;;

    723:   *truncstrat=pipegcr->truncstrat;
    724:   return(0);
    725: }

    729: PetscErrorCode KSPSetFromOptions_PIPEGCR(PetscOptionItems *PetscOptionsObject,KSP ksp)
    730: {
    732:   KSP_PIPEGCR    *pipegcr = (KSP_PIPEGCR*)ksp->data;
    733:   PetscInt       mmax,nprealloc;
    734:   PetscBool      flg;

    737:   PetscOptionsHead(PetscOptionsObject,"KSP PIPEGCR options");
    738:   PetscOptionsInt("-ksp_pipegcr_mmax","Number of search directions to storue","KSPPIPEGCRSetMmax",pipegcr->mmax,&mmax,&flg);
    739:   if (flg) KSPPIPEGCRSetMmax(ksp,mmax);
    740:   PetscOptionsInt("-ksp_pipegcr_nprealloc","Number of directions to preallocate","KSPPIPEGCRSetNprealloc",pipegcr->nprealloc,&nprealloc,&flg);
    741:   if (flg) { KSPPIPEGCRSetNprealloc(ksp,nprealloc); }
    742:   PetscOptionsEnum("-ksp_pipegcr_truncation_type","Truncation approach for directions","KSPFCGSetTruncationType",KSPFCDTruncationTypes,(PetscEnum)pipegcr->truncstrat,(PetscEnum*)&pipegcr->truncstrat,NULL);
    743:   PetscOptionsBool("-ksp_pipegcr_unroll_w","Use unrolling of w","KSPPIPEGCRSetUnrollW",pipegcr->unroll_w,&pipegcr->unroll_w,NULL);
    744:   PetscOptionsTail();
    745:   return(0);
    746: }

    749: typedef PetscErrorCode (*KSPPIPEGCRModifyPCFunction)(KSP,PetscInt,PetscReal,void*);
    750: typedef PetscErrorCode (*KSPPIPEGCRDestroyFunction)(void*);

    754: static PetscErrorCode  KSPPIPEGCRSetModifyPC_PIPEGCR(KSP ksp,KSPPIPEGCRModifyPCFunction function,void *data,KSPPIPEGCRDestroyFunction destroy)
    755: {
    756:   KSP_PIPEGCR *pipegcr = (KSP_PIPEGCR*)ksp->data;

    760:   pipegcr->modifypc         = function;
    761:   pipegcr->modifypc_destroy = destroy;
    762:   pipegcr->modifypc_ctx     = data;
    763:   return(0);
    764: }

    768: /*@C
    769:  KSPPIPEGCRSetModifyPC - Sets the routine used by PIPEGCR to modify the preconditioner.

    771:  Logically Collective on KSP

    773:  Input Parameters:
    774:  +  ksp      - iterative context obtained from KSPCreate()
    775:  .  function - user defined function to modify the preconditioner
    776:  .  ctx      - user provided contex for the modify preconditioner function
    777:  -  destroy  - the function to use to destroy the user provided application context.

    779:  Calling Sequence of function:
    780:   PetscErrorCode function (KSP ksp, PetscInt n, PetscReal rnorm, void *ctx)

    782:  ksp   - iterative context
    783:  n     - the total number of PIPEGCR iterations that have occurred
    784:  rnorm - 2-norm residual value
    785:  ctx   - the user provided application context

    787:  Level: intermediate

    789:  Notes:
    790:  The default modifypc routine is KSPPIPEGCRModifyPCNoChange()

    792:  .seealso: KSPPIPEGCRModifyPCNoChange()

    794:  @*/
    795: PetscErrorCode  KSPPIPEGCRSetModifyPC(KSP ksp,PetscErrorCode (*function)(KSP,PetscInt,PetscReal,void*),void *data,PetscErrorCode (*destroy)(void*))
    796: {

    800:   PetscUseMethod(ksp,"KSPPIPEGCRSetModifyPC_C",(KSP,PetscErrorCode (*)(KSP,PetscInt,PetscReal,void*),void *data,PetscErrorCode (*)(void*)),(ksp,function,data,destroy));
    801:   return(0);
    802: }

    804: /*MC
    805:      KSPPIPEGCR - Implements the preconditioned Generalized Conjugate Residual method with pipelining.

    807:     The PIPEGCR Krylov method supports non-symmetric matrices and permits the use of a preconditioner
    808:     which may vary from one iteration to the next. Users can can define a method to vary the
    809:     preconditioner between iterates via KSPPIPEGCRSetModifyPC().
    810:     Restarts are solves with x0 not equal to zero. When a restart occurs, the initial starting
    811:     solution is given by the current estimate for x which was obtained by the last restart
    812:     iterations of the PIPEGCR algorithm.
    813:     The method implemented requires at most the storage of 4 x mmax + 5 vectors, roughly twice as much as GCR.

    815:     Only supports left preconditioning.

    817:     The natural norm for this method is (u,Au). This norm is available at no computational costs. Choosing norm types preconditioned or unpreconditioned involves a blocking reduction which prevents any benefit from pipelining.

    819:    Options Database Keys:
    820: +   -ksp_pipegcr_mmax <N>  - the max number of Krylov directions to orthogonalize against
    821: .   -ksp_pipegcr_unroll_w - unroll w at the storage cost of a maximum of (mmax+1) extra vectors with the benefit of better pipelining (default: PETSC_TRUE)
    822: .   -ksp_pipegcr_nprealloc <N> - the number of vectors to preallocated for storing Krylov directions. Once exhausted new directions are allocated blockwise (default: 5)
    823: .   -ksp_pipegcr_truncation - Truncate number of previous Krylov directions
    824: -   -ksp_pipegcr_trancation_restart - Truncation-restart strategy: Keep at most mmax Krylov directions then restart (the default)

    826:    Level: beginner

    828:     Reference:
    829:       Pipelined, Flexible Krylov Subspace Methods
    830:       Patrick Sanan, Sascha M. Schnepp, and Dave A. May

    832: .seealso:  KSPCreate(), KSPSetType(), KSPType (for list of available types), KSP,
    833:            KSPPIPEFGMRES, KSPPIPECG, KSPPIPECR, KSPPIPEFCG

    835: M*/
    838: PETSC_EXTERN PetscErrorCode KSPCreate_PIPEGCR(KSP ksp)
    839: {
    841:   KSP_PIPEGCR    *pipegcr;

    844:   PetscNewLog(ksp,&pipegcr);
    845:   pipegcr->mmax       = KSPPIPEGCR_DEFAULT_MMAX;
    846:   pipegcr->nprealloc  = KSPPIPEGCR_DEFAULT_NPREALLOC;
    847:   pipegcr->nvecs      = 0;
    848:   pipegcr->vecb       = KSPPIPEGCR_DEFAULT_VECB;
    849:   pipegcr->nchunks    = 0;
    850:   pipegcr->truncstrat = KSPPIPEGCR_DEFAULT_TRUNCSTRAT;
    851:   pipegcr->n_restarts = 0;
    852:   pipegcr->unroll_w   = KSPPIPEGCR_DEFAULT_UNROLL_W;

    854:   ksp->data       = (void*)pipegcr;

    856:   /* natural norm is for free, precond+unprecond norm require non-overlapped reduction */
    857:   KSPSetSupportedNorm(ksp,KSP_NORM_NATURAL,PC_LEFT,2);
    858:   KSPSetSupportedNorm(ksp,KSP_NORM_PRECONDITIONED,PC_LEFT,1);
    859:   KSPSetSupportedNorm(ksp,KSP_NORM_UNPRECONDITIONED,PC_LEFT,1);

    861:   ksp->ops->setup          = KSPSetUp_PIPEGCR;
    862:   ksp->ops->solve          = KSPSolve_PIPEGCR;
    863:   ksp->ops->reset          = KSPReset_PIPEGCR;
    864:   ksp->ops->destroy        = KSPDestroy_PIPEGCR;
    865:   ksp->ops->view           = KSPView_PIPEGCR;
    866:   ksp->ops->setfromoptions = KSPSetFromOptions_PIPEGCR;
    867:   ksp->ops->buildsolution  = KSPBuildSolutionDefault;
    868:   ksp->ops->buildresidual  = KSPBuildResidualDefault;

    870:   PetscObjectComposeFunction((PetscObject)ksp,"KSPPIPEGCRSetModifyPC_C",KSPPIPEGCRSetModifyPC_PIPEGCR);
    871:   return(0);
    872: }