xref: /petsc/src/ksp/pc/impls/bddc/bddcschurs.c (revision 2bc0d5c782a271179e5f2d71b7baec8c7ad7b879)
1 #include <../src/ksp/pc/impls/bddc/bddc.h>
2 #include <../src/ksp/pc/impls/bddc/bddcprivate.h>
3 
4 static PetscErrorCode PCBDDCAdjGetNextLayer_Private(PetscInt*,PetscInt,PetscBT,PetscInt*,PetscInt*,PetscInt*);
5 
6 #undef __FUNCT__
7 #define __FUNCT__ "PCBDDCSubSchursCreate"
8 PetscErrorCode PCBDDCSubSchursCreate(PCBDDCSubSchurs *sub_schurs)
9 {
10   PCBDDCSubSchurs schurs_ctx;
11   PetscErrorCode  ierr;
12 
13   PetscFunctionBegin;
14   ierr = PetscNew(&schurs_ctx);CHKERRQ(ierr);
15   *sub_schurs = schurs_ctx;
16   PetscFunctionReturn(0);
17 }
18 
19 #undef __FUNCT__
20 #define __FUNCT__ "PCBDDCSubSchursDestroy"
21 PetscErrorCode PCBDDCSubSchursDestroy(PCBDDCSubSchurs *sub_schurs)
22 {
23   PetscErrorCode ierr;
24 
25   PetscFunctionBegin;
26   ierr = PCBDDCSubSchursReset(*sub_schurs);CHKERRQ(ierr);
27   ierr = PetscFree(*sub_schurs);CHKERRQ(ierr);
28   PetscFunctionReturn(0);
29 }
30 
31 #undef __FUNCT__
32 #define __FUNCT__ "PCBDDCSubSchursReset"
33 PetscErrorCode PCBDDCSubSchursReset(PCBDDCSubSchurs sub_schurs)
34 {
35   PetscInt       i;
36   PetscErrorCode ierr;
37 
38   PetscFunctionBegin;
39   for (i=0;i<sub_schurs->n_subs;i++) {
40     ierr = ISDestroy(&sub_schurs->is_AEj_I[i]);CHKERRQ(ierr);
41     ierr = ISDestroy(&sub_schurs->is_AEj_B[i]);CHKERRQ(ierr);
42     ierr = MatDestroy(&sub_schurs->S_Ej[i]);CHKERRQ(ierr);
43     ierr = VecDestroy(&sub_schurs->work1[i]);CHKERRQ(ierr);
44     ierr = VecDestroy(&sub_schurs->work2[i]);CHKERRQ(ierr);
45   }
46   ierr = PetscFree5(sub_schurs->is_AEj_I,sub_schurs->is_AEj_B,sub_schurs->S_Ej,sub_schurs->work1,sub_schurs->work2);CHKERRQ(ierr);
47   sub_schurs->n_subs = 0;
48   PetscFunctionReturn(0);
49 }
50 
51 #undef __FUNCT__
52 #define __FUNCT__ "PCBDDCAdjGetNextLayer_Private"
53 static PetscErrorCode PCBDDCAdjGetNextLayer_Private(PetscInt* queue_tip,PetscInt n_prev,PetscBT touched,PetscInt* xadj,PetscInt* adjncy,PetscInt* n_added)
54 {
55   PetscInt       i,j,n;
56   PetscErrorCode ierr;
57 
58   PetscFunctionBegin;
59   n = 0;
60   for (i=-n_prev;i<0;i++) {
61     PetscInt start_dof = queue_tip[i];
62     for (j=xadj[start_dof];j<xadj[start_dof+1];j++) {
63       PetscInt dof = adjncy[j];
64       if (!PetscBTLookup(touched,dof)) {
65         ierr = PetscBTSet(touched,dof);CHKERRQ(ierr);
66         queue_tip[n] = dof;
67         n++;
68       }
69     }
70   }
71   *n_added = n;
72   PetscFunctionReturn(0);
73 }
74 
75 #undef __FUNCT__
76 #define __FUNCT__ "PCBDDCSubSchursSetUp"
77 PetscErrorCode PCBDDCSubSchursSetUp(PCBDDCSubSchurs sub_schurs, Mat S, IS is_A_I, IS is_A_B, PetscInt ncc, PetscInt cptr[], PetscInt queue[], PetscInt xadj[], PetscInt adjncy[], PetscBool skip_corners, PetscInt nlayers)
78 {
79   Mat                    A_II,A_IB,A_BI,A_BB;
80   ISLocalToGlobalMapping BtoNmap,ItoNmap;
81   PetscBT                touched;
82   PetscInt               i,n_I,n_B,n_local,*local_numbering;
83   PetscBool              is_sorted;
84   PetscErrorCode         ierr;
85 
86   PetscFunctionBegin;
87   ierr = ISSorted(is_A_I,&is_sorted);CHKERRQ(ierr);
88   if (!is_sorted) {
89     SETERRQ(PetscObjectComm((PetscObject)is_A_I),PETSC_ERR_PLIB,"IS for I dofs should be shorted");
90   }
91   ierr = ISSorted(is_A_B,&is_sorted);CHKERRQ(ierr);
92   if (!is_sorted) {
93     SETERRQ(PetscObjectComm((PetscObject)is_A_B),PETSC_ERR_PLIB,"IS for B dofs should be shorted");
94   }
95 
96   /* get sizes */
97   ierr = ISGetLocalSize(is_A_I,&n_I);CHKERRQ(ierr);
98   ierr = ISGetLocalSize(is_A_B,&n_B);CHKERRQ(ierr);
99   n_local = n_I+n_B;
100 
101   /* maps */
102   ierr = ISLocalToGlobalMappingCreateIS(is_A_B,&BtoNmap);CHKERRQ(ierr);
103   if (nlayers >= 0 && xadj != NULL && adjncy != NULL) { /* I problems have a different size of the original ones */
104     ierr = ISLocalToGlobalMappingCreateIS(is_A_I,&ItoNmap);CHKERRQ(ierr);
105     /* allocate some auxiliary space */
106     ierr = PetscMalloc1(n_local,&local_numbering);CHKERRQ(ierr);
107     ierr = PetscBTCreate(n_local,&touched);CHKERRQ(ierr);
108   } else {
109     ItoNmap = 0;
110     local_numbering = 0;
111     touched = 0;
112   }
113 
114   /* get Schur complement matrices */
115   ierr = MatSchurComplementGetSubMatrices(S,&A_II,NULL,&A_IB,&A_BI,&A_BB);CHKERRQ(ierr);
116 
117   /* allocate space for schur complements */
118   ierr = PetscMalloc5(ncc,&sub_schurs->is_AEj_I,ncc,&sub_schurs->is_AEj_B,ncc,&sub_schurs->S_Ej,ncc,&sub_schurs->work1,ncc,&sub_schurs->work2);CHKERRQ(ierr);
119   sub_schurs->n_subs = ncc;
120 
121   /* cycle on subsets and extract schur complements */
122   for (i=0;i<sub_schurs->n_subs;i++) {
123     Mat      AE_II,AE_IE,AE_EI,AE_EE;
124     IS       is_I,is_subset_B;
125     PetscInt subset_size;
126 
127     /* size of subset */
128     subset_size = cptr[i+1]-cptr[i];
129     if (subset_size == 1 && skip_corners) {
130       sub_schurs->is_AEj_B[i] = 0;
131       sub_schurs->is_AEj_I[i] = 0;
132       sub_schurs->S_Ej[i] = 0;
133       sub_schurs->work1[i] = 0;
134       sub_schurs->work2[i] = 0;
135       continue;
136     }
137 
138     /* get IS for subsets in original numbering and in B numbering */
139     ierr = ISCreateGeneral(PetscObjectComm((PetscObject)BtoNmap),subset_size,queue+cptr[i],PETSC_COPY_VALUES,&sub_schurs->is_AEj_B[i]);CHKERRQ(ierr);
140     ierr = ISSort(sub_schurs->is_AEj_B[i]);CHKERRQ(ierr);
141     ierr = ISGlobalToLocalMappingApplyIS(BtoNmap,IS_GTOLM_DROP,sub_schurs->is_AEj_B[i],&is_subset_B);CHKERRQ(ierr);
142 
143     /* BB block on subset */
144     ierr = MatGetSubMatrix(A_BB,is_subset_B,is_subset_B,MAT_INITIAL_MATRIX,&AE_EE);CHKERRQ(ierr);
145 
146     if (ItoNmap) { /* is ItoNmap has been computed, extracts only a part of I dofs */
147       const PetscInt* idx_B;
148       PetscInt        n_local_dofs,n_prev_added,j,layer;
149 
150       /* all boundary dofs must be skipped when adding layers */
151       ierr = PetscBTMemzero(n_local,touched);CHKERRQ(ierr);
152       ierr = ISGetIndices(is_A_B,&idx_B);CHKERRQ(ierr);
153       for (j=0;j<n_B;j++) {
154         ierr = PetscBTSet(touched,idx_B[j]);CHKERRQ(ierr);
155       }
156       ierr = ISRestoreIndices(is_A_B,&idx_B);CHKERRQ(ierr);
157 
158       /* add next layers of dofs */
159       ierr = PetscMemcpy(local_numbering,queue+cptr[i],subset_size*sizeof(PetscInt));CHKERRQ(ierr);
160       n_local_dofs = subset_size;
161       n_prev_added = subset_size;
162       for (layer=0;layer<nlayers;layer++) {
163         PetscInt n_added;
164         if (n_local_dofs == n_I+subset_size) break;
165         if (n_local_dofs > n_I+subset_size) {
166           SETERRQ3(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Error querying layer %d. Out of bound access (%d > %d)",layer,n_local_dofs,n_I+subset_size);
167         }
168         ierr = PCBDDCAdjGetNextLayer_Private(local_numbering+n_local_dofs,n_prev_added,touched,xadj,adjncy,&n_added);CHKERRQ(ierr);
169         n_prev_added = n_added;
170         n_local_dofs += n_added;
171       }
172 
173       /* IS for I dofs in original numbering and in I numbering */
174       ierr = ISCreateGeneral(PetscObjectComm((PetscObject)ItoNmap),n_local_dofs-subset_size,local_numbering+subset_size,PETSC_COPY_VALUES,&sub_schurs->is_AEj_I[i]);CHKERRQ(ierr);
175       ierr = ISSort(sub_schurs->is_AEj_I[i]);CHKERRQ(ierr);
176       ierr = ISGlobalToLocalMappingApplyIS(ItoNmap,IS_GTOLM_DROP,sub_schurs->is_AEj_I[i],&is_I);CHKERRQ(ierr);
177 
178       /* II block */
179       ierr = MatGetSubMatrix(A_II,is_I,is_I,MAT_INITIAL_MATRIX,&AE_II);CHKERRQ(ierr);
180     } else { /* in this case we can take references of already existing IS and matrices for I dofs */
181       /* IS for I dofs in original numbering */
182       ierr = PetscObjectReference((PetscObject)is_A_I);CHKERRQ(ierr);
183       sub_schurs->is_AEj_I[i] = is_A_I;
184 
185       /* IS for I dofs in I numbering TODO: "first" argument of ISCreateStride is not general */
186       ierr = ISCreateStride(PetscObjectComm((PetscObject)is_A_I),n_I,0,1,&is_I);CHKERRQ(ierr);
187 
188       /* II block is the same */
189       ierr = PetscObjectReference((PetscObject)A_II);CHKERRQ(ierr);
190       AE_II = A_II;
191     }
192 
193     /* IE block */
194     ierr = MatGetSubMatrix(A_IB,is_I,is_subset_B,MAT_INITIAL_MATRIX,&AE_IE);CHKERRQ(ierr);
195 
196     /* EI block */
197     ierr = MatGetSubMatrix(A_BI,is_subset_B,is_I,MAT_INITIAL_MATRIX,&AE_EI);CHKERRQ(ierr);
198 
199     /* setup Schur complements on subset */
200     ierr = MatCreateSchurComplement(AE_II,AE_II,AE_IE,AE_EI,AE_EE,&sub_schurs->S_Ej[i]);CHKERRQ(ierr);
201     ierr = MatGetVecs(sub_schurs->S_Ej[i],&sub_schurs->work1[i],&sub_schurs->work2[i]);CHKERRQ(ierr);
202     if (AE_II == A_II) { /* we can reuse the same ksp */
203       KSP ksp;
204       ierr = MatSchurComplementGetKSP(S,&ksp);CHKERRQ(ierr);
205       ierr = MatSchurComplementSetKSP(sub_schurs->S_Ej[i],ksp);CHKERRQ(ierr);
206     } else { /* build new ksp object which inherits ksp and pc types from the original one */
207       KSP      origksp,schurksp;
208       PC       origpc,schurpc;
209       KSPType  ksp_type;
210       PCType   pc_type;
211       PetscInt n_internal;
212 
213       ierr = MatSchurComplementGetKSP(S,&origksp);CHKERRQ(ierr);
214       ierr = MatSchurComplementGetKSP(sub_schurs->S_Ej[i],&schurksp);CHKERRQ(ierr);
215       ierr = KSPGetType(origksp,&ksp_type);CHKERRQ(ierr);
216       ierr = KSPSetType(schurksp,ksp_type);CHKERRQ(ierr);
217       ierr = KSPGetPC(schurksp,&schurpc);CHKERRQ(ierr);
218       ierr = KSPGetPC(origksp,&origpc);CHKERRQ(ierr);
219       ierr = PCGetType(origpc,&pc_type);CHKERRQ(ierr);
220       ierr = PCSetType(schurpc,pc_type);CHKERRQ(ierr);
221       ierr = ISGetSize(is_I,&n_internal);CHKERRQ(ierr);
222       if (n_internal) { /* UMFPACK gives error with 0 sized problems */
223         MatSolverPackage solver=NULL;
224         ierr = PCFactorGetMatSolverPackage(origpc,(const MatSolverPackage*)&solver);CHKERRQ(ierr);
225         if (solver) {
226           ierr = PCFactorSetMatSolverPackage(schurpc,solver);CHKERRQ(ierr);
227         }
228       }
229       ierr = KSPSetUp(schurksp);CHKERRQ(ierr);
230     }
231     /* free */
232     ierr = MatDestroy(&AE_II);CHKERRQ(ierr);
233     ierr = MatDestroy(&AE_EE);CHKERRQ(ierr);
234     ierr = MatDestroy(&AE_IE);CHKERRQ(ierr);
235     ierr = MatDestroy(&AE_EI);CHKERRQ(ierr);
236     ierr = ISDestroy(&is_I);CHKERRQ(ierr);
237     ierr = ISDestroy(&is_subset_B);CHKERRQ(ierr);
238   }
239   /* free */
240   ierr = ISLocalToGlobalMappingDestroy(&ItoNmap);CHKERRQ(ierr);
241   ierr = ISLocalToGlobalMappingDestroy(&BtoNmap);CHKERRQ(ierr);
242   ierr = PetscFree(local_numbering);CHKERRQ(ierr);
243   ierr = PetscBTDestroy(&touched);CHKERRQ(ierr);
244   PetscFunctionReturn(0);
245 }
246