1 2 /* 3 This file defines a "solve the problem redistributely on each subgroup of processor" preconditioner. 4 */ 5 #include <private/pcimpl.h> /*I "petscksp.h" I*/ 6 #include <petscksp.h> 7 8 typedef struct { 9 KSP ksp; 10 Vec x,b; 11 VecScatter scatter; 12 IS is; 13 PetscInt dcnt,*drows; /* these are the local rows that have only diagonal entry */ 14 PetscScalar *diag; 15 Vec work; 16 } PC_Redistribute; 17 18 #undef __FUNCT__ 19 #define __FUNCT__ "PCView_Redistribute" 20 static PetscErrorCode PCView_Redistribute(PC pc,PetscViewer viewer) 21 { 22 PC_Redistribute *red = (PC_Redistribute*)pc->data; 23 PetscErrorCode ierr; 24 PetscBool iascii,isstring; 25 PetscInt ncnt,N; 26 27 PetscFunctionBegin; 28 ierr = PetscTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr); 29 ierr = PetscTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr); 30 if (iascii) { 31 ierr = MPI_Allreduce(&red->dcnt,&ncnt,1,MPIU_INT,MPI_SUM,((PetscObject)pc)->comm);CHKERRQ(ierr); 32 ierr = MatGetSize(pc->pmat,&N,PETSC_NULL);CHKERRQ(ierr); 33 ierr = PetscViewerASCIIPrintf(viewer," Number rows eliminated %D Percentage rows eliminated %g\n",ncnt,100.0*((PetscReal)ncnt)/((PetscReal)N));CHKERRQ(ierr); 34 ierr = PetscViewerASCIIPrintf(viewer," Redistribute preconditioner: \n");CHKERRQ(ierr); 35 ierr = KSPView(red->ksp,viewer);CHKERRQ(ierr); 36 } else if (isstring) { 37 ierr = PetscViewerStringSPrintf(viewer," Redistribute preconditioner");CHKERRQ(ierr); 38 ierr = KSPView(red->ksp,viewer);CHKERRQ(ierr); 39 } else { 40 SETERRQ1(((PetscObject)pc)->comm,PETSC_ERR_SUP,"Viewer type %s not supported for PC redistribute",((PetscObject)viewer)->type_name); 41 } 42 PetscFunctionReturn(0); 43 } 44 45 #undef __FUNCT__ 46 #define __FUNCT__ "PCSetUp_Redistribute" 47 static PetscErrorCode PCSetUp_Redistribute(PC pc) 48 { 49 PC_Redistribute *red = (PC_Redistribute*)pc->data; 50 PetscErrorCode ierr; 51 MPI_Comm comm; 52 PetscInt rstart,rend,i,nz,cnt,*rows,ncnt,dcnt,*drows; 53 PetscLayout map,nmap; 54 PetscMPIInt size,imdex,tag,n; 55 PetscInt *source = PETSC_NULL; 56 PetscMPIInt *nprocs = PETSC_NULL,nrecvs; 57 PetscInt j,nsends; 58 PetscInt *owner = PETSC_NULL,*starts = PETSC_NULL,count,slen; 59 PetscInt *rvalues,*svalues,recvtotal; 60 PetscMPIInt *onodes1,*olengths1; 61 MPI_Request *send_waits = PETSC_NULL,*recv_waits = PETSC_NULL; 62 MPI_Status recv_status,*send_status; 63 Vec tvec,diag; 64 Mat tmat; 65 const PetscScalar *d; 66 67 PetscFunctionBegin; 68 if (pc->setupcalled) { 69 ierr = KSPGetOperators(red->ksp,PETSC_NULL,&tmat,PETSC_NULL);CHKERRQ(ierr); 70 ierr = MatGetSubMatrix(pc->pmat,red->is,red->is,MAT_REUSE_MATRIX,&tmat);CHKERRQ(ierr); 71 ierr = KSPSetOperators(red->ksp,tmat,tmat,SAME_NONZERO_PATTERN);CHKERRQ(ierr); 72 } else { 73 PetscInt NN; 74 75 ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr); 76 ierr = MPI_Comm_size(comm,&size);CHKERRQ(ierr); 77 ierr = PetscObjectGetNewTag((PetscObject)pc,&tag);CHKERRQ(ierr); 78 79 /* count non-diagonal rows on process */ 80 ierr = MatGetOwnershipRange(pc->mat,&rstart,&rend);CHKERRQ(ierr); 81 cnt = 0; 82 for (i=rstart; i<rend; i++) { 83 ierr = MatGetRow(pc->mat,i,&nz,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr); 84 if (nz > 1) cnt++; 85 ierr = MatRestoreRow(pc->mat,i,&nz,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr); 86 } 87 ierr = PetscMalloc(cnt*sizeof(PetscInt),&rows);CHKERRQ(ierr); 88 ierr = PetscMalloc((rend - rstart - cnt)*sizeof(PetscInt),&drows);CHKERRQ(ierr); 89 90 /* list non-diagonal rows on process */ 91 cnt = 0; dcnt = 0; 92 for (i=rstart; i<rend; i++) { 93 ierr = MatGetRow(pc->mat,i,&nz,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr); 94 if (nz > 1) rows[cnt++] = i; 95 else drows[dcnt++] = i - rstart; 96 ierr = MatRestoreRow(pc->mat,i,&nz,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr); 97 } 98 99 /* create PetscLayout for non-diagonal rows on each process */ 100 ierr = PetscLayoutCreate(comm,&map);CHKERRQ(ierr); 101 ierr = PetscLayoutSetLocalSize(map,cnt);CHKERRQ(ierr); 102 ierr = PetscLayoutSetBlockSize(map,1);CHKERRQ(ierr); 103 ierr = PetscLayoutSetUp(map);CHKERRQ(ierr); 104 rstart = map->rstart; 105 rend = map->rend; 106 107 /* create PetscLayout for load-balanced non-diagonal rows on each process */ 108 ierr = PetscLayoutCreate(comm,&nmap);CHKERRQ(ierr); 109 ierr = MPI_Allreduce(&cnt,&ncnt,1,MPIU_INT,MPI_SUM,comm);CHKERRQ(ierr); 110 ierr = PetscLayoutSetSize(nmap,ncnt);CHKERRQ(ierr); 111 ierr = PetscLayoutSetBlockSize(nmap,1);CHKERRQ(ierr); 112 ierr = PetscLayoutSetUp(nmap);CHKERRQ(ierr); 113 114 ierr = MatGetSize(pc->pmat,&NN,PETSC_NULL);CHKERRQ(ierr); 115 ierr = PetscInfo2(pc,"Number of diagonal rows eliminated %d, percentage eliminated %g\n",NN-ncnt,((PetscReal)(NN-ncnt))/((PetscReal)(NN))); 116 /* 117 this code is taken from VecScatterCreate_PtoS() 118 Determines what rows need to be moved where to 119 load balance the non-diagonal rows 120 */ 121 /* count number of contributors to each processor */ 122 ierr = PetscMalloc2(size,PetscMPIInt,&nprocs,cnt,PetscInt,&owner);CHKERRQ(ierr); 123 ierr = PetscMemzero(nprocs,size*sizeof(PetscMPIInt));CHKERRQ(ierr); 124 j = 0; 125 nsends = 0; 126 for (i=rstart; i<rend; i++) { 127 if (i < nmap->range[j]) j = 0; 128 for (; j<size; j++) { 129 if (i < nmap->range[j+1]) { 130 if (!nprocs[j]++) nsends++; 131 owner[i-rstart] = j; 132 break; 133 } 134 } 135 } 136 /* inform other processors of number of messages and max length*/ 137 ierr = PetscGatherNumberOfMessages(comm,PETSC_NULL,nprocs,&nrecvs);CHKERRQ(ierr); 138 ierr = PetscGatherMessageLengths(comm,nsends,nrecvs,nprocs,&onodes1,&olengths1);CHKERRQ(ierr); 139 ierr = PetscSortMPIIntWithArray(nrecvs,onodes1,olengths1);CHKERRQ(ierr); 140 recvtotal = 0; for (i=0; i<nrecvs; i++) recvtotal += olengths1[i]; 141 142 /* post receives: rvalues - rows I will own; count - nu */ 143 ierr = PetscMalloc3(recvtotal,PetscInt,&rvalues,nrecvs,PetscInt,&source,nrecvs,MPI_Request,&recv_waits);CHKERRQ(ierr); 144 count = 0; 145 for (i=0; i<nrecvs; i++) { 146 ierr = MPI_Irecv((rvalues+count),olengths1[i],MPIU_INT,onodes1[i],tag,comm,recv_waits+i);CHKERRQ(ierr); 147 count += olengths1[i]; 148 } 149 150 /* do sends: 151 1) starts[i] gives the starting index in svalues for stuff going to 152 the ith processor 153 */ 154 ierr = PetscMalloc3(cnt,PetscInt,&svalues,nsends,MPI_Request,&send_waits,size,PetscInt,&starts);CHKERRQ(ierr); 155 starts[0] = 0; 156 for (i=1; i<size; i++) { starts[i] = starts[i-1] + nprocs[i-1];} 157 for (i=0; i<cnt; i++) { 158 svalues[starts[owner[i]]++] = rows[i]; 159 } 160 for (i=0; i<cnt; i++) rows[i] = rows[i] - rstart; 161 red->drows = drows; 162 red->dcnt = dcnt; 163 ierr = PetscFree(rows);CHKERRQ(ierr); 164 165 starts[0] = 0; 166 for (i=1; i<size; i++) { starts[i] = starts[i-1] + nprocs[i-1];} 167 count = 0; 168 for (i=0; i<size; i++) { 169 if (nprocs[i]) { 170 ierr = MPI_Isend(svalues+starts[i],nprocs[i],MPIU_INT,i,tag,comm,send_waits+count++);CHKERRQ(ierr); 171 } 172 } 173 174 /* wait on receives */ 175 count = nrecvs; 176 slen = 0; 177 while (count) { 178 ierr = MPI_Waitany(nrecvs,recv_waits,&imdex,&recv_status);CHKERRQ(ierr); 179 /* unpack receives into our local space */ 180 ierr = MPI_Get_count(&recv_status,MPIU_INT,&n);CHKERRQ(ierr); 181 slen += n; 182 count--; 183 } 184 if (slen != recvtotal) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Total message lengths %D not expected %D",slen,recvtotal); 185 186 ierr = ISCreateGeneral(comm,slen,rvalues,PETSC_COPY_VALUES,&red->is);CHKERRQ(ierr); 187 188 /* free up all work space */ 189 ierr = PetscFree(olengths1);CHKERRQ(ierr); 190 ierr = PetscFree(onodes1);CHKERRQ(ierr); 191 ierr = PetscFree3(rvalues,source,recv_waits);CHKERRQ(ierr); 192 ierr = PetscFree2(nprocs,owner);CHKERRQ(ierr); 193 if (nsends) { /* wait on sends */ 194 ierr = PetscMalloc(nsends*sizeof(MPI_Status),&send_status);CHKERRQ(ierr); 195 ierr = MPI_Waitall(nsends,send_waits,send_status);CHKERRQ(ierr); 196 ierr = PetscFree(send_status);CHKERRQ(ierr); 197 } 198 ierr = PetscFree3(svalues,send_waits,starts);CHKERRQ(ierr); 199 ierr = PetscLayoutDestroy(&map);CHKERRQ(ierr); 200 ierr = PetscLayoutDestroy(&nmap);CHKERRQ(ierr); 201 202 ierr = VecCreateMPI(comm,slen,PETSC_DETERMINE,&red->b);CHKERRQ(ierr); 203 ierr = VecDuplicate(red->b,&red->x);CHKERRQ(ierr); 204 ierr = MatGetVecs(pc->pmat,&tvec,PETSC_NULL);CHKERRQ(ierr); 205 ierr = VecScatterCreate(tvec,red->is,red->b,PETSC_NULL,&red->scatter);CHKERRQ(ierr); 206 ierr = VecDestroy(&tvec);CHKERRQ(ierr); 207 ierr = MatGetSubMatrix(pc->pmat,red->is,red->is,MAT_INITIAL_MATRIX,&tmat);CHKERRQ(ierr); 208 ierr = KSPSetOperators(red->ksp,tmat,tmat,SAME_NONZERO_PATTERN);CHKERRQ(ierr); 209 ierr = MatDestroy(&tmat);CHKERRQ(ierr); 210 } 211 212 /* get diagonal portion of matrix */ 213 ierr = PetscMalloc(red->dcnt*sizeof(PetscScalar),&red->diag);CHKERRQ(ierr); 214 ierr = MatGetVecs(pc->pmat,&diag,PETSC_NULL);CHKERRQ(ierr); 215 ierr = MatGetDiagonal(pc->pmat,diag);CHKERRQ(ierr); 216 ierr = VecGetArrayRead(diag,&d);CHKERRQ(ierr); 217 for (i=0; i<red->dcnt; i++) { 218 red->diag[i] = 1.0/d[red->drows[i]]; 219 } 220 ierr = VecRestoreArrayRead(diag,&d);CHKERRQ(ierr); 221 ierr = VecDestroy(&diag);CHKERRQ(ierr); 222 ierr = KSPSetUp(red->ksp);CHKERRQ(ierr); 223 PetscFunctionReturn(0); 224 } 225 226 #undef __FUNCT__ 227 #define __FUNCT__ "PCApply_Redistribute" 228 static PetscErrorCode PCApply_Redistribute(PC pc,Vec b,Vec x) 229 { 230 PC_Redistribute *red = (PC_Redistribute*)pc->data; 231 PetscErrorCode ierr; 232 PetscInt dcnt = red->dcnt,i; 233 const PetscInt *drows = red->drows; 234 PetscScalar *xwork; 235 const PetscScalar *bwork,*diag = red->diag; 236 237 PetscFunctionBegin; 238 if (!red->work) { 239 ierr = VecDuplicate(b,&red->work);CHKERRQ(ierr); 240 } 241 /* compute the rows of solution that have diagonal entries only */ 242 ierr = VecSet(x,0.0);CHKERRQ(ierr); /* x = diag(A)^{-1} b */ 243 ierr = VecGetArray(x,&xwork);CHKERRQ(ierr); 244 ierr = VecGetArrayRead(b,&bwork);CHKERRQ(ierr); 245 for (i=0; i<dcnt; i++) { 246 xwork[drows[i]] = diag[i]*bwork[drows[i]]; 247 } 248 ierr = PetscLogFlops(dcnt);CHKERRQ(ierr); 249 ierr = VecRestoreArray(red->work,&xwork);CHKERRQ(ierr); 250 ierr = VecRestoreArrayRead(b,&bwork);CHKERRQ(ierr); 251 /* update the right hand side for the reduced system with diagonal rows (and corresponding columns) removed */ 252 ierr = MatMult(pc->pmat,x,red->work);CHKERRQ(ierr); 253 ierr = VecAYPX(red->work,-1.0,b);CHKERRQ(ierr); /* red->work = b - A x */ 254 255 ierr = VecScatterBegin(red->scatter,red->work,red->b,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr); 256 ierr = VecScatterEnd(red->scatter,red->work,red->b,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr); 257 ierr = KSPSolve(red->ksp,red->b,red->x);CHKERRQ(ierr); 258 ierr = VecScatterBegin(red->scatter,red->x,x,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr); 259 ierr = VecScatterEnd(red->scatter,red->x,x,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr); 260 PetscFunctionReturn(0); 261 } 262 263 #undef __FUNCT__ 264 #define __FUNCT__ "PCDestroy_Redistribute" 265 static PetscErrorCode PCDestroy_Redistribute(PC pc) 266 { 267 PC_Redistribute *red = (PC_Redistribute*)pc->data; 268 PetscErrorCode ierr; 269 270 PetscFunctionBegin; 271 ierr = VecScatterDestroy(&red->scatter);CHKERRQ(ierr); 272 ierr = ISDestroy(&red->is);CHKERRQ(ierr); 273 ierr = VecDestroy(&red->b);CHKERRQ(ierr); 274 ierr = VecDestroy(&red->x);CHKERRQ(ierr); 275 ierr = KSPDestroy(&red->ksp);CHKERRQ(ierr); 276 ierr = VecDestroy(&red->work);CHKERRQ(ierr); 277 ierr = PetscFree(red->drows); 278 ierr = PetscFree(red->diag); 279 ierr = PetscFree(pc->data);CHKERRQ(ierr); 280 PetscFunctionReturn(0); 281 } 282 283 #undef __FUNCT__ 284 #define __FUNCT__ "PCSetFromOptions_Redistribute" 285 static PetscErrorCode PCSetFromOptions_Redistribute(PC pc) 286 { 287 PetscErrorCode ierr; 288 PC_Redistribute *red = (PC_Redistribute*)pc->data; 289 290 PetscFunctionBegin; 291 ierr = KSPSetFromOptions(red->ksp);CHKERRQ(ierr); 292 PetscFunctionReturn(0); 293 } 294 295 #undef __FUNCT__ 296 #define __FUNCT__ "PCRedistributeGetKSP" 297 /*@ 298 PCRedistributeGetKSP - Gets the KSP created by the PCREDISTRIBUTE 299 300 Not Collective 301 302 Input Parameter: 303 . pc - the preconditioner context 304 305 Output Parameter: 306 . innerksp - the inner KSP 307 308 Level: advanced 309 310 .keywords: PC, redistribute solve 311 @*/ 312 PetscErrorCode PCRedistributeGetKSP(PC pc,KSP *innerksp) 313 { 314 PC_Redistribute *red = (PC_Redistribute*)pc->data; 315 316 PetscFunctionBegin; 317 PetscValidHeaderSpecific(pc,PC_CLASSID,1); 318 PetscValidPointer(innerksp,2); 319 *innerksp = red->ksp; 320 PetscFunctionReturn(0); 321 } 322 323 /* -------------------------------------------------------------------------------------*/ 324 /*MC 325 PCREDISTRIBUTE - Redistributes a matrix for load balancing, removing the rows that only have a diagonal entry and then applys a KSP to that new matrix 326 327 Options for the redistribute preconditioners can be set with -redistribute_ksp_xxx <values> and -redistribute_pc_xxx <values> 328 329 Notes: Usually run this with -ksp_type preonly 330 331 If you have used MatZeroRows() to eliminate (for example, Dirichlet) boundary conditions for a symmetric problem then you can use, for example, -ksp_type preonly 332 -pc_type redistribute -redistribute_ksp_type cg -redistribute_pc_type bjacobi -redistribute_sub_pc_type icc to take advantage of the symmetry. 333 334 Level: intermediate 335 336 .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PCRedistributeGetKSP() 337 M*/ 338 339 EXTERN_C_BEGIN 340 #undef __FUNCT__ 341 #define __FUNCT__ "PCCreate_Redistribute" 342 PetscErrorCode PCCreate_Redistribute(PC pc) 343 { 344 PetscErrorCode ierr; 345 PC_Redistribute *red; 346 const char *prefix; 347 348 PetscFunctionBegin; 349 ierr = PetscNewLog(pc,PC_Redistribute,&red);CHKERRQ(ierr); 350 pc->data = (void*)red; 351 352 pc->ops->apply = PCApply_Redistribute; 353 pc->ops->applytranspose = 0; 354 pc->ops->setup = PCSetUp_Redistribute; 355 pc->ops->destroy = PCDestroy_Redistribute; 356 pc->ops->setfromoptions = PCSetFromOptions_Redistribute; 357 pc->ops->view = PCView_Redistribute; 358 359 ierr = KSPCreate(((PetscObject)pc)->comm,&red->ksp);CHKERRQ(ierr); 360 ierr = PetscObjectIncrementTabLevel((PetscObject)red->ksp,(PetscObject)pc,1);CHKERRQ(ierr); 361 ierr = PetscLogObjectParent(pc,red->ksp);CHKERRQ(ierr); 362 ierr = PCGetOptionsPrefix(pc,&prefix);CHKERRQ(ierr); 363 ierr = KSPSetOptionsPrefix(red->ksp,prefix);CHKERRQ(ierr); 364 ierr = KSPAppendOptionsPrefix(red->ksp,"redistribute_");CHKERRQ(ierr); 365 PetscFunctionReturn(0); 366 } 367 EXTERN_C_END 368