1 2 /* 3 Provides utility routines for split MPI communicator. 4 */ 5 #include <petscsys.h> /*I "petscsys.h" I*/ 6 7 extern PetscErrorCode PetscSubcommCreate_contiguous(PetscSubcomm); 8 extern PetscErrorCode PetscSubcommCreate_interlaced(PetscSubcomm); 9 10 #undef __FUNCT__ 11 #define __FUNCT__ "PetscSubcommSetNumber" 12 /*@C 13 PetscSubcommSetNumber - Set total number of subcommunicators. 14 15 Collective on MPI_Comm 16 17 Input Parameter: 18 + psubcomm - PetscSubcomm context 19 - nsubcomm - the total number of subcommunicators in psubcomm 20 21 Level: advanced 22 23 .keywords: communicator 24 25 .seealso: PetscSubcommCreate(),PetscSubcommDestroy(),PetscSubcommSetType(),PetscSubcommSetTypeGeneral() 26 @*/ 27 PetscErrorCode PetscSubcommSetNumber(PetscSubcomm psubcomm,PetscInt nsubcomm) 28 { 29 PetscErrorCode ierr; 30 MPI_Comm comm=psubcomm->parent; 31 PetscMPIInt rank,size; 32 33 PetscFunctionBegin; 34 if (!psubcomm) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_NULL,"PetscSubcomm is not created. Call PetscSubcommCreate() first"); 35 ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr); 36 ierr = MPI_Comm_size(comm,&size);CHKERRQ(ierr); 37 if (nsubcomm < 1 || nsubcomm > size) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Num of subcommunicators %D cannot be < 1 or > input comm size %D",nsubcomm,size); 38 39 psubcomm->n = nsubcomm; 40 PetscFunctionReturn(0); 41 } 42 43 #undef __FUNCT__ 44 #define __FUNCT__ "PetscSubcommSetType" 45 /*@C 46 PetscSubcommSetType - Set type of subcommunicators. 47 48 Collective on MPI_Comm 49 50 Input Parameter: 51 + psubcomm - PetscSubcomm context 52 - subcommtype - subcommunicator type, PETSC_SUBCOMM_CONTIGUOUS,PETSC_SUBCOMM_INTERLACED 53 54 Level: advanced 55 56 .keywords: communicator 57 58 .seealso: PetscSubcommCreate(),PetscSubcommDestroy(),PetscSubcommSetNumber(),PetscSubcommSetTypeGeneral() 59 @*/ 60 PetscErrorCode PetscSubcommSetType(PetscSubcomm psubcomm,const PetscSubcommType subcommtype) 61 { 62 PetscErrorCode ierr; 63 64 PetscFunctionBegin; 65 if (!psubcomm) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_NULL,"PetscSubcomm is not created. Call PetscSubcommCreate()"); 66 if (psubcomm->n < 1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"number of subcommunicators %D is incorrect. Call PetscSubcommSetNumber()",psubcomm->n); 67 68 if (subcommtype == PETSC_SUBCOMM_CONTIGUOUS){ 69 ierr = PetscSubcommCreate_contiguous(psubcomm);CHKERRQ(ierr); 70 } else if (subcommtype == PETSC_SUBCOMM_INTERLACED){ 71 ierr = PetscSubcommCreate_interlaced(psubcomm);CHKERRQ(ierr); 72 } else { 73 SETERRQ1(psubcomm->parent,PETSC_ERR_SUP,"PetscSubcommType %D is not supported yet",subcommtype); 74 } 75 PetscFunctionReturn(0); 76 } 77 78 #undef __FUNCT__ 79 #define __FUNCT__ "PetscSubcommSetTypeGeneral" 80 /*@C 81 PetscSubcommSetTypeGeneral - Set type of subcommunicators from user's specifications 82 83 Collective on MPI_Comm 84 85 Input Parameter: 86 + psubcomm - PetscSubcomm context 87 . color - control of subset assignment (nonnegative integer). Processes with the same color are in the same subcommunicator. 88 . subrank - rank in the subcommunicator 89 - duprank - rank in the dupparent (see PetscSubcomm) 90 91 Level: advanced 92 93 .keywords: communicator, create 94 95 .seealso: PetscSubcommCreate(),PetscSubcommDestroy(),PetscSubcommSetNumber(),PetscSubcommSetType() 96 @*/ 97 PetscErrorCode PetscSubcommSetTypeGeneral(PetscSubcomm psubcomm,PetscMPIInt color,PetscMPIInt subrank,PetscMPIInt duprank) 98 { 99 PetscErrorCode ierr; 100 MPI_Comm subcomm=0,dupcomm=0,comm=psubcomm->parent; 101 PetscMPIInt size; 102 103 PetscFunctionBegin; 104 if (!psubcomm) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_NULL,"PetscSubcomm is not created. Call PetscSubcommCreate()"); 105 if (psubcomm->n < 1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"number of subcommunicators %D is incorrect. Call PetscSubcommSetNumber()",psubcomm->n); 106 107 ierr = MPI_Comm_split(comm,color,subrank,&subcomm);CHKERRQ(ierr); 108 109 /* create dupcomm with same size as comm, but its rank, duprank, maps subcomm's contiguously into dupcomm 110 if duprank is not a valid number, then dupcomm is not created - not all applications require dupcomm! */ 111 ierr = MPI_Comm_size(comm,&size);CHKERRQ(ierr); 112 if (duprank == PETSC_DECIDE){ 113 SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"duprank==PETSC_DECIDE is not supported yet"); 114 } else if (duprank >= 0 && duprank < size){ 115 ierr = MPI_Comm_split(comm,0,duprank,&dupcomm);CHKERRQ(ierr); 116 } 117 ierr = PetscCommDuplicate(dupcomm,&psubcomm->dupparent,PETSC_NULL);CHKERRQ(ierr); 118 ierr = PetscCommDuplicate(subcomm,&psubcomm->comm,PETSC_NULL);CHKERRQ(ierr); 119 ierr = MPI_Comm_free(&dupcomm);CHKERRQ(ierr); 120 ierr = MPI_Comm_free(&subcomm);CHKERRQ(ierr); 121 psubcomm->color = color; 122 PetscFunctionReturn(0); 123 } 124 125 #undef __FUNCT__ 126 #define __FUNCT__ "PetscSubcommDestroy" 127 PetscErrorCode PetscSubcommDestroy(PetscSubcomm *psubcomm) 128 { 129 PetscErrorCode ierr; 130 131 PetscFunctionBegin; 132 if (!*psubcomm) PetscFunctionReturn(0); 133 ierr = PetscCommDestroy(&(*psubcomm)->dupparent);CHKERRQ(ierr); 134 ierr = PetscCommDestroy(&(*psubcomm)->comm);CHKERRQ(ierr); 135 ierr = PetscFree((*psubcomm));CHKERRQ(ierr); 136 PetscFunctionReturn(0); 137 } 138 139 #undef __FUNCT__ 140 #define __FUNCT__ "PetscSubcommCreate" 141 /*@C 142 PetscSubcommCreate - Create a PetscSubcomm context. 143 144 Collective on MPI_Comm 145 146 Input Parameter: 147 . comm - MPI communicator 148 149 Output Parameter: 150 . psubcomm - location to store the PetscSubcomm context 151 152 Level: advanced 153 154 .keywords: communicator, create 155 156 .seealso: PetscSubcommDestroy() 157 @*/ 158 PetscErrorCode PetscSubcommCreate(MPI_Comm comm,PetscSubcomm *psubcomm) 159 { 160 PetscErrorCode ierr; 161 162 PetscFunctionBegin; 163 164 ierr = PetscNew(struct _n_PetscSubcomm,psubcomm);CHKERRQ(ierr); 165 (*psubcomm)->parent = comm; 166 PetscFunctionReturn(0); 167 } 168 169 #undef __FUNCT__ 170 #define __FUNCT__ "PetscSubcommCreate_contiguous" 171 PetscErrorCode PetscSubcommCreate_contiguous(PetscSubcomm psubcomm) 172 { 173 PetscErrorCode ierr; 174 PetscMPIInt rank,size,*subsize,duprank=-1,subrank=-1; 175 PetscInt np_subcomm,nleftover,i,color=-1,rankstart,nsubcomm=psubcomm->n; 176 MPI_Comm subcomm=0,dupcomm=0,comm=psubcomm->parent; 177 178 PetscFunctionBegin; 179 ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr); 180 ierr = MPI_Comm_size(comm,&size);CHKERRQ(ierr); 181 182 /* get size of each subcommunicator */ 183 ierr = PetscMalloc((1+nsubcomm)*sizeof(PetscMPIInt),&subsize);CHKERRQ(ierr); 184 np_subcomm = size/nsubcomm; 185 nleftover = size - nsubcomm*np_subcomm; 186 for (i=0; i<nsubcomm; i++){ 187 subsize[i] = np_subcomm; 188 if (i<nleftover) subsize[i]++; 189 } 190 191 /* get color and subrank of this proc */ 192 rankstart = 0; 193 for (i=0; i<nsubcomm; i++){ 194 if ( rank >= rankstart && rank < rankstart+subsize[i]) { 195 color = i; 196 subrank = rank - rankstart; 197 duprank = rank; 198 break; 199 } else { 200 rankstart += subsize[i]; 201 } 202 } 203 ierr = PetscFree(subsize);CHKERRQ(ierr); 204 205 ierr = MPI_Comm_split(comm,color,subrank,&subcomm);CHKERRQ(ierr); 206 207 /* create dupcomm with same size as comm, but its rank, duprank, maps subcomm's contiguously into dupcomm */ 208 ierr = MPI_Comm_split(comm,0,duprank,&dupcomm);CHKERRQ(ierr); 209 210 ierr = PetscCommDuplicate(dupcomm,&psubcomm->dupparent,PETSC_NULL);CHKERRQ(ierr); 211 ierr = PetscCommDuplicate(subcomm,&psubcomm->comm,PETSC_NULL);CHKERRQ(ierr); 212 ierr = MPI_Comm_free(&dupcomm);CHKERRQ(ierr); 213 ierr = MPI_Comm_free(&subcomm);CHKERRQ(ierr); 214 psubcomm->color = color; 215 PetscFunctionReturn(0); 216 } 217 218 #undef __FUNCT__ 219 #define __FUNCT__ "PetscSubcommCreate_interlaced" 220 /* 221 Note: 222 In PCREDUNDANT, to avoid data scattering from subcomm back to original comm, we create subcommunicators 223 by iteratively taking a process into a subcommunicator. 224 Example: size=4, nsubcomm=(*psubcomm)->n=3 225 comm=(*psubcomm)->parent: 226 rank: [0] [1] [2] [3] 227 color: 0 1 2 0 228 229 subcomm=(*psubcomm)->comm: 230 subrank: [0] [0] [0] [1] 231 232 dupcomm=(*psubcomm)->dupparent: 233 duprank: [0] [2] [3] [1] 234 235 Here, subcomm[color = 0] has subsize=2, owns process [0] and [3] 236 subcomm[color = 1] has subsize=1, owns process [1] 237 subcomm[color = 2] has subsize=1, owns process [2] 238 dupcomm has same number of processes as comm, and its duprank maps 239 processes in subcomm contiguously into a 1d array: 240 duprank: [0] [1] [2] [3] 241 rank: [0] [3] [1] [2] 242 subcomm[0] subcomm[1] subcomm[2] 243 */ 244 245 PetscErrorCode PetscSubcommCreate_interlaced(PetscSubcomm psubcomm) 246 { 247 PetscErrorCode ierr; 248 PetscMPIInt rank,size,*subsize,duprank,subrank; 249 PetscInt np_subcomm,nleftover,i,j,color,nsubcomm=psubcomm->n; 250 MPI_Comm subcomm=0,dupcomm=0,comm=psubcomm->parent; 251 252 PetscFunctionBegin; 253 ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr); 254 ierr = MPI_Comm_size(comm,&size);CHKERRQ(ierr); 255 256 /* get size of each subcommunicator */ 257 ierr = PetscMalloc((1+nsubcomm)*sizeof(PetscMPIInt),&subsize);CHKERRQ(ierr); 258 np_subcomm = size/nsubcomm; 259 nleftover = size - nsubcomm*np_subcomm; 260 for (i=0; i<nsubcomm; i++){ 261 subsize[i] = np_subcomm; 262 if (i<nleftover) subsize[i]++; 263 } 264 265 /* find color for this proc */ 266 color = rank%nsubcomm; 267 subrank = rank/nsubcomm; 268 269 ierr = MPI_Comm_split(comm,color,subrank,&subcomm);CHKERRQ(ierr); 270 271 j = 0; duprank = 0; 272 for (i=0; i<nsubcomm; i++){ 273 if (j == color){ 274 duprank += subrank; 275 break; 276 } 277 duprank += subsize[i]; j++; 278 } 279 ierr = PetscFree(subsize);CHKERRQ(ierr); 280 281 /* create dupcomm with same size as comm, but its rank, duprank, maps subcomm's contiguously into dupcomm */ 282 ierr = MPI_Comm_split(comm,0,duprank,&dupcomm);CHKERRQ(ierr); 283 284 ierr = PetscCommDuplicate(dupcomm,&psubcomm->dupparent,PETSC_NULL);CHKERRQ(ierr); 285 ierr = PetscCommDuplicate(subcomm,&psubcomm->comm,PETSC_NULL);CHKERRQ(ierr); 286 ierr = MPI_Comm_free(&dupcomm);CHKERRQ(ierr); 287 ierr = MPI_Comm_free(&subcomm);CHKERRQ(ierr); 288 psubcomm->color = color; 289 PetscFunctionReturn(0); 290 } 291 292 293