xref: /petsc/src/dm/tutorials/ex14.c (revision b122ec5aa1bd4469eb4e0673542fb7de3f411254)
1 
2 static char help[] = "Tests DMCreateDomainDecomposition.\n\n";
3 
4 /*
5 Use the options
6      -da_grid_x <nx> - number of grid points in x direction, if M < 0
7      -da_grid_y <ny> - number of grid points in y direction, if N < 0
8      -da_processors_x <MX> number of processors in x directio
9      -da_processors_y <MY> number of processors in x direction
10 */
11 
12 #include <petscdm.h>
13 #include <petscdmda.h>
14 
15 PetscErrorCode FillLocalSubdomain(DM da, Vec gvec)
16 {
17   DMDALocalInfo  info;
18   PetscMPIInt    rank;
19   PetscInt       i,j,k,l;
20   PetscErrorCode ierr;
21 
22   PetscFunctionBeginUser;
23   CHKERRMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank));
24   CHKERRQ(DMDAGetLocalInfo(da,&info));
25 
26   if (info.dim == 3) {
27     PetscScalar    ***g;
28     CHKERRQ(DMDAVecGetArray(da,gvec,&g));
29     /* loop over ghosts */
30     for (k=info.zs; k<info.zs+info.zm; k++) {
31       for (j=info.ys; j<info.ys+info.ym; j++) {
32         for (i=info.xs; i<info.xs+info.xm; i++) {
33           g[k][j][info.dof*i+0]   = i;
34           g[k][j][info.dof*i+1]   = j;
35           g[k][j][info.dof*i+2]   = k;
36         }
37       }
38     }
39     CHKERRQ(DMDAVecRestoreArray(da,gvec,&g));
40   }
41   if (info.dim == 2) {
42     PetscScalar    **g;
43     CHKERRQ(DMDAVecGetArray(da,gvec,&g));
44     /* loop over ghosts */
45     for (j=info.ys; j<info.ys+info.ym; j++) {
46       for (i=info.xs; i<info.xs+info.xm; i++) {
47         for (l = 0;l<info.dof;l++) {
48           g[j][info.dof*i+0]   = i;
49           g[j][info.dof*i+1]   = j;
50           g[j][info.dof*i+2]   = rank;
51         }
52       }
53     }
54     CHKERRQ(DMDAVecRestoreArray(da,gvec,&g));
55   }
56   PetscFunctionReturn(0);
57 }
58 
59 int main(int argc,char **argv)
60 {
61   PetscErrorCode ierr;
62   DM             da,*subda;
63   PetscInt       i,dim = 3;
64   PetscInt       M = 25, N = 25, P = 25;
65   PetscMPIInt    size,rank;
66   Vec            v;
67   Vec            slvec,sgvec;
68   IS             *ois,*iis;
69   VecScatter     oscata;
70   VecScatter     *iscat,*oscat,*gscat;
71   DMDALocalInfo  info;
72   PetscBool      patchis_offproc = PETSC_TRUE;
73 
74   CHKERRQ(PetscInitialize(&argc,&argv,(char*)0,help));
75   CHKERRQ(PetscOptionsGetInt(NULL,NULL,"-dim",&dim,NULL));
76 
77   /* Create distributed array and get vectors */
78   CHKERRMPI(MPI_Comm_size(PETSC_COMM_WORLD,&size));
79   CHKERRMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank));
80   if (dim == 2) {
81     CHKERRQ(DMDACreate2d(PETSC_COMM_WORLD,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,M,N,PETSC_DECIDE,PETSC_DECIDE,3,1,NULL,NULL,&da));
82   } else if (dim == 3) {
83     CHKERRQ(DMDACreate3d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,M,N,P,PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE,3,1,NULL,NULL,NULL,&da));
84   }
85   CHKERRQ(DMSetFromOptions(da));
86   CHKERRQ(DMSetUp(da));
87   CHKERRQ(DMDAGetLocalInfo(da,&info));
88 
89   CHKERRQ(DMCreateDomainDecomposition(da,NULL,NULL,&iis,&ois,&subda));
90   CHKERRQ(DMCreateDomainDecompositionScatters(da,1,subda,&iscat,&oscat,&gscat));
91 
92   {
93     DMDALocalInfo subinfo;
94     MatStencil    lower,upper;
95     IS            patchis;
96     Vec           smallvec;
97     Vec           largevec;
98     VecScatter    patchscat;
99 
100     CHKERRQ(DMDAGetLocalInfo(subda[0],&subinfo));
101 
102     lower.i = info.xs;
103     lower.j = info.ys;
104     lower.k = info.zs;
105     upper.i = info.xs+info.xm;
106     upper.j = info.ys+info.ym;
107     upper.k = info.zs+info.zm;
108 
109     /* test the patch IS as a thing to scatter to/from */
110     CHKERRQ(DMDACreatePatchIS(da,&lower,&upper,&patchis,patchis_offproc));
111     CHKERRQ(DMGetGlobalVector(da,&largevec));
112 
113     CHKERRQ(VecCreate(PETSC_COMM_SELF,&smallvec));
114     CHKERRQ(VecSetSizes(smallvec,info.dof*(upper.i - lower.i)*(upper.j - lower.j)*(upper.k - lower.k),PETSC_DECIDE));
115     CHKERRQ(VecSetFromOptions(smallvec));
116     CHKERRQ(VecScatterCreate(smallvec,NULL,largevec,patchis,&patchscat));
117 
118     CHKERRQ(FillLocalSubdomain(subda[0],smallvec));
119     CHKERRQ(VecSet(largevec,0));
120 
121     CHKERRQ(VecScatterBegin(patchscat,smallvec,largevec,ADD_VALUES,SCATTER_FORWARD));
122     CHKERRQ(VecScatterEnd(patchscat,smallvec,largevec,ADD_VALUES,SCATTER_FORWARD));
123     CHKERRQ(ISView(patchis,PETSC_VIEWER_STDOUT_WORLD));
124     CHKERRQ(VecScatterView(patchscat,PETSC_VIEWER_STDOUT_WORLD));
125 
126     for (i = 0; i < size; i++) {
127       if (i == rank) {
128         CHKERRQ(VecView(smallvec,PETSC_VIEWER_STDOUT_SELF));
129       }
130       CHKERRMPI(MPI_Barrier(PETSC_COMM_WORLD));
131     }
132 
133     CHKERRMPI(MPI_Barrier(PETSC_COMM_WORLD));
134     CHKERRQ(VecView(largevec,PETSC_VIEWER_STDOUT_WORLD));
135 
136     CHKERRQ(VecDestroy(&smallvec));
137     CHKERRQ(DMRestoreGlobalVector(da,&largevec));
138     CHKERRQ(ISDestroy(&patchis));
139     CHKERRQ(VecScatterDestroy(&patchscat));
140   }
141 
142   /* view the various parts */
143   {
144     for (i = 0; i < size; i++) {
145       if (i == rank) {
146         CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"Processor %d: \n",i));
147         CHKERRQ(DMView(subda[0],PETSC_VIEWER_STDOUT_SELF));
148       }
149       CHKERRMPI(MPI_Barrier(PETSC_COMM_WORLD));
150     }
151 
152     CHKERRQ(DMGetLocalVector(subda[0],&slvec));
153     CHKERRQ(DMGetGlobalVector(subda[0],&sgvec));
154     CHKERRQ(DMGetGlobalVector(da,&v));
155 
156     /* test filling outer between the big DM and the small ones with the IS scatter*/
157     CHKERRQ(VecScatterCreate(v,ois[0],sgvec,NULL,&oscata));
158 
159     CHKERRQ(FillLocalSubdomain(subda[0],sgvec));
160 
161     CHKERRQ(VecScatterBegin(oscata,sgvec,v,ADD_VALUES,SCATTER_REVERSE));
162     CHKERRQ(VecScatterEnd(oscata,sgvec,v,ADD_VALUES,SCATTER_REVERSE));
163 
164     /* test the local-to-local scatter */
165 
166     /* fill up the local subdomain and then add them together */
167     CHKERRQ(FillLocalSubdomain(da,v));
168 
169     CHKERRQ(VecScatterBegin(gscat[0],v,slvec,ADD_VALUES,SCATTER_FORWARD));
170     CHKERRQ(VecScatterEnd(gscat[0],v,slvec,ADD_VALUES,SCATTER_FORWARD));
171 
172     CHKERRQ(VecView(v,PETSC_VIEWER_STDOUT_WORLD));
173 
174     /* test ghost scattering backwards */
175 
176     CHKERRQ(VecSet(v,0));
177 
178     CHKERRQ(VecScatterBegin(gscat[0],slvec,v,ADD_VALUES,SCATTER_REVERSE));
179     CHKERRQ(VecScatterEnd(gscat[0],slvec,v,ADD_VALUES,SCATTER_REVERSE));
180 
181     CHKERRQ(VecView(v,PETSC_VIEWER_STDOUT_WORLD));
182 
183     /* test overlap scattering backwards */
184 
185     CHKERRQ(DMLocalToGlobalBegin(subda[0],slvec,ADD_VALUES,sgvec));
186     CHKERRQ(DMLocalToGlobalEnd(subda[0],slvec,ADD_VALUES,sgvec));
187 
188     CHKERRQ(VecSet(v,0));
189 
190     CHKERRQ(VecScatterBegin(oscat[0],sgvec,v,ADD_VALUES,SCATTER_REVERSE));
191     CHKERRQ(VecScatterEnd(oscat[0],sgvec,v,ADD_VALUES,SCATTER_REVERSE));
192 
193     CHKERRQ(VecView(v,PETSC_VIEWER_STDOUT_WORLD));
194 
195     /* test interior scattering backwards */
196 
197     CHKERRQ(VecSet(v,0));
198 
199     CHKERRQ(VecScatterBegin(iscat[0],sgvec,v,ADD_VALUES,SCATTER_REVERSE));
200     CHKERRQ(VecScatterEnd(iscat[0],sgvec,v,ADD_VALUES,SCATTER_REVERSE));
201 
202     CHKERRQ(VecView(v,PETSC_VIEWER_STDOUT_WORLD));
203 
204     /* test matrix allocation */
205     for (i = 0; i < size; i++) {
206       if (i == rank) {
207         Mat m;
208         CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"Processor %d: \n",i));
209         CHKERRQ(DMSetMatType(subda[0],MATAIJ));
210         CHKERRQ(DMCreateMatrix(subda[0],&m));
211         CHKERRQ(MatView(m,PETSC_VIEWER_STDOUT_SELF));
212         CHKERRQ(MatDestroy(&m));
213       }
214       CHKERRMPI(MPI_Barrier(PETSC_COMM_WORLD));
215     }
216     CHKERRQ(DMRestoreLocalVector(subda[0],&slvec));
217     CHKERRQ(DMRestoreGlobalVector(subda[0],&sgvec));
218     CHKERRQ(DMRestoreGlobalVector(da,&v));
219   }
220 
221   CHKERRQ(DMDestroy(&subda[0]));
222   CHKERRQ(ISDestroy(&ois[0]));
223   CHKERRQ(ISDestroy(&iis[0]));
224 
225   CHKERRQ(VecScatterDestroy(&iscat[0]));
226   CHKERRQ(VecScatterDestroy(&oscat[0]));
227   CHKERRQ(VecScatterDestroy(&gscat[0]));
228   CHKERRQ(VecScatterDestroy(&oscata));
229 
230   CHKERRQ(PetscFree(iscat));
231   CHKERRQ(PetscFree(oscat));
232   CHKERRQ(PetscFree(gscat));
233   CHKERRQ(PetscFree(oscata));
234 
235   CHKERRQ(PetscFree(subda));
236   CHKERRQ(PetscFree(ois));
237   CHKERRQ(PetscFree(iis));
238 
239   CHKERRQ(DMDestroy(&da));
240   CHKERRQ(PetscFinalize());
241   return 0;
242 }
243