Actual source code: ex61f.F90

petsc-3.14.0 2020-09-29
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  1: !
  2: !        Demonstrates having each OpenMP thread manage its own PETSc objects and solves
  3: !           - each thread is ONLY allowed to access objects that IT created
  4: !                  that is, threads cannot shared objects
  5: !
  6: !        Run with "export OMP_NUM_THREADS=16 ./ex61f"
  7: !           to use 16 independent threads
  8: !
  9: !        ./configure --with-threadsafety --with-log=0 --with-openmp
 10: !
 11:          module omp_module
 12:          implicit none
 13:          contains
 14:          subroutine split_indices(total,num_pieces,ibeg,iend)
 15:            implicit none

 17:            integer :: total
 18:            integer :: num_pieces
 19:            integer :: ibeg(num_pieces), iend(num_pieces)
 20:            integer :: itmp1, itmp2, ioffset, i

 22:            itmp1 = total/num_pieces
 23:            itmp2 = mod(total,num_pieces)
 24:            ioffset = 0
 25:            do i=1,itmp2
 26:               ibeg(i) = ioffset + 1
 27:               iend(i) = ioffset + (itmp1+1)
 28:               ioffset = iend(i)
 29:            enddo
 30:            do i=itmp2+1,num_pieces
 31:               ibeg(i) = ioffset + 1
 32:               if (ibeg(i) > total) then
 33:                  iend(i) = ibeg(i) - 1
 34:               else
 35:                  iend(i) = ioffset + itmp1
 36:                  ioffset = iend(i)
 37:               endif
 38:            enddo

 40:          end subroutine split_indices
 41:        end module omp_module

 43:       module assert_mod
 44:       implicit none
 45:       contains
 46:       subroutine assert(lcond,msg,icase)
 47:       logical,intent(in) :: lcond
 48:       character(len=*), intent(in) :: msg
 49:       integer, intent(in) :: icase

 51:       if (.not.lcond) then
 52:          write(*,*) msg, icase
 53:          stop 'assertion error '
 54:       endif
 55:       return
 56:       end subroutine assert
 57:       end module assert_mod

 59:       program tpetsc

 61: #include <petsc/finclude/petsc.h>
 62:       use assert_mod
 63:       use omp_module
 64:       use petsc
 65:       implicit none
 66: !     ----------------------------
 67: !     test concurrent petsc solver
 68: !     ----------------------------

 70:       integer, parameter :: NCASES=100
 71:       integer, parameter :: MAXTHREADS=64
 72:       real(8), parameter :: tol = 1.0d-6

 74:       integer, dimension(MAXTHREADS) :: ibeg,iend

 76: !$   integer, external :: omp_get_num_threads

 78:       Mat, target :: Mcol_f_mat(MAXTHREADS)
 79:       Vec, target :: Mcol_f_vecb(MAXTHREADS)
 80:       Vec, target :: Mcol_f_vecx(MAXTHREADS)
 81:       KSP, target :: Mcol_f_ksp(MAXTHREADS)
 82:       PC,  target :: MPC(MAXTHREADS)

 84:       Mat, pointer :: col_f_mat
 85:       Vec, pointer :: col_f_vecb
 86:       Vec, pointer :: col_f_vecx
 87:       KSP, pointer :: col_f_ksp
 88:       PC, pointer :: pc

 90:       PetscInt :: ith, nthreads
 91:       PetscErrorCode ierr

 93:       integer, parameter :: nz_per_row = 9
 94:       integer, parameter :: n =100
 95:       integer :: i,j,ij,ij2,ii,jj,nz,ip, dx,dy,icase
 96:       integer, allocatable :: ilist(:),jlist(:)
 97:       PetscScalar :: aij
 98:       PetscScalar, allocatable :: alist(:)
 99:       logical :: isvalid_ii, isvalid_jj, is_diag

101:       PetscInt nrow
102:       PetscInt ncol
103:       PetscScalar, allocatable :: x(:), b(:)
104:       real(8) :: err(NCASES)

106:       integer :: t1,t2,count_rate
107:       real :: ttime

109:       call PetscInitialize(PETSC_NULL_CHARACTER,ierr)
110:       if (ierr .ne. 0) then
111:         print*,'Unable to initialize PETSc'
112:         stop
113:       endif

115:       allocate(ilist(n*n*nz_per_row),jlist(n*n*nz_per_row),alist(n*n*nz_per_row))
116:       allocate(x(0:(n*n-1)),b(0:(n*n-1)))
117:       nrow = n*n
118:       ncol = nrow

120:       nthreads = 1
121: !$omp parallel
122: !$omp master
123: !$      nthreads = omp_get_num_threads()
124: !$omp end master
125: !$omp end parallel
126:       print*,'nthreads = ', nthreads,' NCASES = ', NCASES

128:       call split_indices(NCASES,nthreads,ibeg,iend)


131: !$omp parallel do                                                        &
132: !$omp private(ith,ierr)                                                  &
133: !$omp private(col_f_mat,col_f_vecb,col_f_vecx,col_f_ksp)
134:       do ith=1,nthreads
135:          col_f_mat => Mcol_f_mat(ith)
136:          col_f_vecb => Mcol_f_vecb(ith)
137:          col_f_vecx => Mcol_f_vecx(ith)
138:          col_f_ksp => Mcol_f_ksp(ith)


141:          call MatCreateSeqAIJ( PETSC_COMM_SELF, nrow,ncol, nz_per_row,PETSC_NULL_INTEGER, col_f_mat, ierr)
142:          call assert(ierr.eq.0,'matcreateseqaij return ',ierr)

144:          call VecCreateSeqWithArray(PETSC_COMM_SELF,1,nrow,PETSC_NULL_SCALAR, col_f_vecb, ierr)
145:          call assert(ierr.eq.0,'veccreateseqwitharray return ierr',ierr)

147:          call VecDuplicate(col_f_vecb, col_f_vecx,ierr)
148:          call assert(ierr.eq.0,'vecduplicate return ierr',ierr)

150:          call KSPCreate(PETSC_COMM_SELF, col_f_ksp,ierr)
151:          call assert(ierr.eq.0,'kspcreate return ierr',ierr)

153:        enddo

155: !      -----------------------
156: !      setup sparsity pattern
157: !      -----------------------
158:        nz = 0
159:        do j=1,n
160:        do i=1,n
161:         ij = i + (j-1)*n
162:         do dx=-1,1
163:         do dy=-1,1
164:           ii = i + dx
165:           jj = j + dy

167:           ij2 = ii + (jj-1)*n
168:           isvalid_ii = (1 <= ii).and.(ii <= n)
169:           isvalid_jj = (1 <= jj).and.(jj <= n)
170:           if (isvalid_ii.and.isvalid_jj) then
171:              is_diag = (ij .eq. ij2)
172:              nz = nz + 1
173:              ilist(nz) = ij
174:              jlist(nz) = ij2
175:              if (is_diag) then
176:                aij = 4.0
177:              else
178:                aij = -1.0
179:              endif
180:              alist(nz) = aij
181:            endif
182:           enddo
183:           enddo
184:          enddo
185:          enddo

187:        print*,'nz = ', nz

189: !      ---------------------------------
190: !      convert from fortan to c indexing
191: !      ---------------------------------
192:        ilist(1:nz) = ilist(1:nz) - 1
193:        jlist(1:nz) = jlist(1:nz) - 1


196: !      --------------
197: !      setup matrices
198: !      --------------
199:        call system_clock(t1,count_rate)

201: !$omp  parallel do                                                      &
202: !$omp& private(ith,icase,ip,i,j,ii,jj,aij,ierr,x,b)                      &
203: !$omp& private(col_f_mat,col_f_vecb,col_f_vecx,col_f_ksp,pc)
204:        do ith=1,nthreads
205:          col_f_mat => Mcol_f_mat(ith)
206:          col_f_vecb => Mcol_f_vecb(ith)
207:          col_f_vecx => Mcol_f_vecx(ith)
208:          col_f_ksp => Mcol_f_ksp(ith)
209:          pc => MPC(ith)

211:         do icase=ibeg(ith),iend(ith)

213:          do ip=1,nz
214:            ii = ilist(ip)
215:            jj = jlist(ip)
216:            aij = alist(ip)
217:            call MatSetValue(col_f_mat,ii,jj,aij,INSERT_VALUES,ierr)
218:            call assert(ierr.eq.0,'matsetvalue return ierr',ierr)
219:          enddo
220:          call MatAssemblyBegin(col_f_mat,MAT_FINAL_ASSEMBLY,ierr)
221:          call assert(ierr.eq.0,'matassemblybegin return ierr',ierr)

223:          call MatAssemblyEnd(col_f_mat,MAT_FINAL_ASSEMBLY,ierr)
224:          call assert(ierr.eq.0,'matassemblyend return ierr',ierr)

226:          call KSPSetOperators(col_f_ksp,col_f_mat,col_f_mat,ierr)
227:          call assert(ierr.eq.0,'KSPSetOperators return ierr',ierr)

229:          ! set linear solver
230:          call KSPGetPC(col_f_ksp,pc,ierr)
231:          call assert(ierr.eq.0,'KSPGetPC return ierr ', ierr)

233:          call PCSetType(pc,PCLU,ierr)
234:          call assert(ierr.eq.0,'PCSetType return ierr ',ierr)

236:          ! associate petsc vector with allocated array
237:          x(:) = 1
238: !$omp    critical
239:          call VecPlaceArray(col_f_vecx,x,ierr)
240: !$omp    end critical
241:          call assert(ierr.eq.0,'VecPlaceArray col_f_vecx return ',ierr)

243:          b(:) = 0
244:          do ip=1,nz
245:            i = ilist(ip)
246:            j = jlist(ip)
247:            aij = alist(ip)
248:            b(i) = b(i) + aij*x(j)
249:          enddo
250:          x = 0
251: !$omp    critical
252:          call VecPlaceArray(col_f_vecb,b,ierr)
253: !$omp    end critical
254:          call assert(ierr.eq.0,'VecPlaceArray col_f_vecb return ',ierr)



258: !  -----------------------------------------------------------
259: !  key test, need to solve multiple linear systems in parallel
260: !  -----------------------------------------------------------
261:          call KSPSetFromOptions(col_f_ksp,ierr)
262:          call assert(ierr.eq.0,'KSPSetFromOptions return ierr ',ierr)

264:          call KSPSetUp(col_f_ksp,ierr)
265:          call assert(ierr.eq.0,'KSPSetup return ierr ',ierr)


268:          call KSPSolve(col_f_ksp,col_f_vecb,col_f_vecx,ierr)
269:          call assert(ierr.eq.0,'KSPSolve return ierr ',ierr)


272: !        ------------
273: !        check answer
274: !        ------------
275:          err(icase) = maxval(abs(x(:)-1))

277: !$omp    critical
278:          call VecResetArray(col_f_vecx,ierr)
279: !$omp    end critical
280:          call assert(ierr.eq.0,'VecResetArray return ierr ',ierr)

282: !$omp    critical
283:          call VecResetArray(col_f_vecb,ierr)
284: !$omp    end critical
285:          call assert(ierr.eq.0,'VecResetArray return ierr ',ierr)

287:        enddo
288:        enddo

290: !$omp parallel do                                                        &
291: !$omp private(ith,ierr)                                                  &
292: !$omp private(col_f_mat,col_f_vecb,col_f_vecx,col_f_ksp)
293:       do ith=1,nthreads
294:          col_f_mat => Mcol_f_mat(ith)
295:          col_f_vecb => Mcol_f_vecb(ith)
296:          col_f_vecx => Mcol_f_vecx(ith)
297:          col_f_ksp => Mcol_f_ksp(ith)


300:          call MatDestroy(col_f_mat, ierr)
301:          call assert(ierr.eq.0,'matdestroy return ',ierr)

303:          call VecDestroy(col_f_vecb, ierr)
304:          call assert(ierr.eq.0,'vecdestroy return ierr',ierr)

306:          call VecDestroy(col_f_vecx,ierr)
307:          call assert(ierr.eq.0,'vecdestroy return ierr',ierr)

309:          call KSPDestroy(col_f_ksp,ierr)
310:          call assert(ierr.eq.0,'kspdestroy return ierr',ierr)

312:        enddo

314:        call system_clock(t2,count_rate)
315:        ttime = real(t2-t1)/real(count_rate)
316:        write(*,*) 'total time is ',ttime

318:        write(*,*) 'maxval(err) ', maxval(err)
319:        do icase=1,NCASES
320:         if (err(icase) > tol) then
321:          write(*,*) 'icase,err(icase) ',icase,err(icase)
322:         endif
323:        enddo

325:        deallocate(ilist,jlist,alist)
326:        deallocate(x,b)
327:        call PetscFinalize(ierr)
328:        call assert(ierr.eq.0,'petscfinalize return ierr',ierr)

330:        end program tpetsc

332: !/*TEST
333: !
334: !   build:
335: !      requires: double !complex !define(PETSC_USE_64BIT_INDICES)
336: !
337: !   test:
338: !      output_file: output/ex61f_1.out
339: !      TODO: Need to determine how to test OpenMP code
340: !
341: !TEST*/