xref: /petsc/src/ksp/pc/impls/bddc/bddcschurs.c (revision 2a155e38474621d83e80fdec7e0211de894e3553)
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 PETSC_STATIC_INLINE 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, IS is_cc[], PetscInt xadj[], PetscInt adjncy[], PetscInt nlayers)
78 {
79   Mat                    A_II,A_IB,A_BI,A_BB;
80   Mat                    AE_II,*AE_IE,*AE_EI,*AE_EE;
81   IS                     is_I,*is_subset_B;
82   ISLocalToGlobalMapping BtoNmap;
83   PetscInt               i;
84   PetscBool              is_sorted;
85   PetscErrorCode         ierr;
86 
87   PetscFunctionBegin;
88   ierr = ISSorted(is_A_I,&is_sorted);CHKERRQ(ierr);
89   if (!is_sorted) {
90     SETERRQ(PetscObjectComm((PetscObject)is_A_I),PETSC_ERR_PLIB,"IS for I dofs should be shorted");
91   }
92   ierr = ISSorted(is_A_B,&is_sorted);CHKERRQ(ierr);
93   if (!is_sorted) {
94     SETERRQ(PetscObjectComm((PetscObject)is_A_B),PETSC_ERR_PLIB,"IS for B dofs should be shorted");
95   }
96 
97   /* get Schur complement matrices */
98   ierr = MatSchurComplementGetSubMatrices(S,&A_II,NULL,&A_IB,&A_BI,&A_BB);CHKERRQ(ierr);
99 
100   /* allocate space for schur complements */
101   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);
102   ierr = PetscMalloc4(ncc,&is_subset_B,ncc,&AE_IE,ncc,&AE_EI,ncc,&AE_EE);CHKERRQ(ierr);
103   sub_schurs->n_subs = ncc;
104 
105   /* maps */
106   if (sub_schurs->n_subs && nlayers >= 0 && xadj != NULL && adjncy != NULL) { /* Interior problems can be different from the original one */
107     ISLocalToGlobalMapping ItoNmap;
108     PetscBT                touched;
109     const PetscInt*        idx_B;
110     PetscInt               n_I,n_B,n_local_dofs,n_prev_added,j,layer,*local_numbering;
111 
112     /* get sizes */
113     ierr = ISGetLocalSize(is_A_I,&n_I);CHKERRQ(ierr);
114     ierr = ISGetLocalSize(is_A_B,&n_B);CHKERRQ(ierr);
115 
116     ierr = ISLocalToGlobalMappingCreateIS(is_A_I,&ItoNmap);CHKERRQ(ierr);
117     ierr = PetscMalloc1(n_I+n_B,&local_numbering);CHKERRQ(ierr);
118     ierr = PetscBTCreate(n_I+n_B,&touched);CHKERRQ(ierr);
119     ierr = PetscBTMemzero(n_I+n_B,touched);CHKERRQ(ierr);
120 
121     /* all boundary dofs must be skipped when adding layers */
122     ierr = ISGetIndices(is_A_B,&idx_B);CHKERRQ(ierr);
123     for (j=0;j<n_B;j++) {
124       ierr = PetscBTSet(touched,idx_B[j]);CHKERRQ(ierr);
125     }
126     ierr = PetscMemcpy(local_numbering,idx_B,n_B*sizeof(PetscInt));CHKERRQ(ierr);
127     ierr = ISRestoreIndices(is_A_B,&idx_B);CHKERRQ(ierr);
128 
129     /* add next layers of dofs */
130     n_local_dofs = n_B;
131     n_prev_added = n_B;
132     for (layer=0;layer<nlayers;layer++) {
133       PetscInt n_added;
134       if (n_local_dofs == n_I+n_B) break;
135       if (n_local_dofs > n_I+n_B) {
136         SETERRQ3(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Error querying layer %d. Out of bound access (%d > %d)",layer,n_local_dofs,n_I+n_B);
137       }
138       ierr = PCBDDCAdjGetNextLayer_Private(local_numbering+n_local_dofs,n_prev_added,touched,xadj,adjncy,&n_added);CHKERRQ(ierr);
139       n_prev_added = n_added;
140       n_local_dofs += n_added;
141       if (!n_added) break;
142     }
143     ierr = PetscBTDestroy(&touched);CHKERRQ(ierr);
144 
145     /* IS for I dofs in original numbering and in I numbering */
146     ierr = ISCreateGeneral(PetscObjectComm((PetscObject)ItoNmap),n_local_dofs-n_B,local_numbering+n_B,PETSC_COPY_VALUES,&sub_schurs->is_AEj_I[0]);CHKERRQ(ierr);
147     ierr = PetscFree(local_numbering);CHKERRQ(ierr);
148     ierr = ISSort(sub_schurs->is_AEj_I[0]);CHKERRQ(ierr);
149     ierr = ISGlobalToLocalMappingApplyIS(ItoNmap,IS_GTOLM_DROP,sub_schurs->is_AEj_I[0],&is_I);CHKERRQ(ierr);
150     ierr = ISLocalToGlobalMappingDestroy(&ItoNmap);CHKERRQ(ierr);
151 
152     /* II block */
153     ierr = MatGetSubMatrix(A_II,is_I,is_I,MAT_INITIAL_MATRIX,&AE_II);CHKERRQ(ierr);
154   } else {
155     PetscInt n_I;
156 
157     /* IS for I dofs in original numbering */
158     ierr = PetscObjectReference((PetscObject)is_A_I);CHKERRQ(ierr);
159     sub_schurs->is_AEj_I[0] = is_A_I;
160 
161     /* IS for I dofs in I numbering (strided 1) */
162     ierr = ISGetSize(is_A_I,&n_I);CHKERRQ(ierr);
163     ierr = ISCreateStride(PetscObjectComm((PetscObject)is_A_I),n_I,0,1,&is_I);CHKERRQ(ierr);
164 
165     /* II block is the same */
166     ierr = PetscObjectReference((PetscObject)A_II);CHKERRQ(ierr);
167     AE_II = A_II;
168   }
169 
170   /* TODO: just for compatibility with the previous version, needs to be fixed */
171   for (i=1;i<sub_schurs->n_subs;i++) {
172     ierr = PetscObjectReference((PetscObject)sub_schurs->is_AEj_I[0]);CHKERRQ(ierr);
173     sub_schurs->is_AEj_I[i] = sub_schurs->is_AEj_I[0];
174   }
175 
176   /* subsets in original and boundary numbering */
177   ierr = ISLocalToGlobalMappingCreateIS(is_A_B,&BtoNmap);CHKERRQ(ierr);
178   for (i=0;i<sub_schurs->n_subs;i++) {
179     ierr = ISDuplicate(is_cc[i],&sub_schurs->is_AEj_B[i]);CHKERRQ(ierr);
180     ierr = ISSort(sub_schurs->is_AEj_B[i]);CHKERRQ(ierr);
181     ierr = ISGlobalToLocalMappingApplyIS(BtoNmap,IS_GTOLM_DROP,sub_schurs->is_AEj_B[i],&is_subset_B[i]);CHKERRQ(ierr);
182   }
183   ierr = ISLocalToGlobalMappingDestroy(&BtoNmap);CHKERRQ(ierr);
184 
185   /* EE block */
186   for (i=0;i<sub_schurs->n_subs;i++) {
187     ierr = MatGetSubMatrix(A_BB,is_subset_B[i],is_subset_B[i],MAT_INITIAL_MATRIX,&AE_EE[i]);CHKERRQ(ierr);
188   }
189   /* IE block */
190   for (i=0;i<sub_schurs->n_subs;i++) {
191     ierr = MatGetSubMatrix(A_IB,is_I,is_subset_B[i],MAT_INITIAL_MATRIX,&AE_IE[i]);CHKERRQ(ierr);
192   }
193   /* EI block */
194   for (i=0;i<sub_schurs->n_subs;i++) {
195     ierr = MatGetSubMatrix(A_BI,is_subset_B[i],is_I,MAT_INITIAL_MATRIX,&AE_EI[i]);CHKERRQ(ierr);
196   }
197 
198   /* setup Schur complements on subset */
199   for (i=0;i<sub_schurs->n_subs;i++) {
200     ierr = MatCreateSchurComplement(AE_II,AE_II,AE_IE[i],AE_EI[i],AE_EE[i],&sub_schurs->S_Ej[i]);CHKERRQ(ierr);
201     ierr = MatCreateVecs(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   }
232   /* free */
233   ierr = ISDestroy(&is_I);CHKERRQ(ierr);
234   ierr = MatDestroy(&AE_II);CHKERRQ(ierr);
235   for (i=0;i<sub_schurs->n_subs;i++) {
236     ierr = MatDestroy(&AE_EE[i]);CHKERRQ(ierr);
237     ierr = MatDestroy(&AE_IE[i]);CHKERRQ(ierr);
238     ierr = MatDestroy(&AE_EI[i]);CHKERRQ(ierr);
239     ierr = ISDestroy(&is_subset_B[i]);CHKERRQ(ierr);
240   }
241   ierr = PetscFree4(is_subset_B,AE_IE,AE_EI,AE_EE);CHKERRQ(ierr);
242   PetscFunctionReturn(0);
243 }
244