!
!
! AMG4PSBLAS version 1.0
! Algebraic Multigrid Package
! based on PSBLAS (Parallel Sparse BLAS version 3.7)
!
! (C) Copyright 2021
!
! Salvatore Filippone
! Pasqua D'Ambra
! Fabio Durastante
!
! Redistribution and use in source and binary forms, with or without
! modification, are permitted provided that the following conditions
! are met:
! 1. Redistributions of source code must retain the above copyright
! notice, this list of conditions and the following disclaimer.
! 2. Redistributions in binary form must reproduce the above copyright
! notice, this list of conditions, and the following disclaimer in the
! documentation and/or other materials provided with the distribution.
! 3. The name of the AMG4PSBLAS group or the names of its contributors may
! not be used to endorse or promote products derived from this
! software without specific written permission.
!
! THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
! ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
! TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
! PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AMG4PSBLAS GROUP OR ITS CONTRIBUTORS
! BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
! CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
! SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
! INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
! CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
! ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
! POSSIBILITY OF SUCH DAMAGE.
!
!
!
! File: amg_z_soc1_map__bld.f90
!
! Subroutine: amg_z_soc1_map_bld
! Version: complex
!
! This routine builds the tentative prolongator based on the
! strength of connection aggregation algorithm presented in
!
! M. Brezina and P. Vanek, A black-box iterative solver based on a
! two-level Schwarz method, Computing, 63 (1999), 233-263.
! P. Vanek, J. Mandel and M. Brezina, Algebraic Multigrid by Smoothed
! Aggregation for Second and Fourth Order Elliptic Problems, Computing, 56
! (1996), 179-196.
!
! Note: upon exit
!
! Arguments:
! a - type(psb_zspmat_type).
! The sparse matrix structure containing the local part of the
! matrix to be preconditioned.
! desc_a - type(psb_desc_type), input.
! The communication descriptor of a.
! p - type(amg_zprec_type), input/output.
! The preconditioner data structure; upon exit it contains
! the multilevel hierarchy of prolongators, restrictors
! and coarse matrices.
! info - integer, output.
! Error code.
!
!
!
subroutine amg_z_soc1_map_bld(iorder,theta,clean_zeros,a,desc_a,nlaggr,ilaggr,info)
use psb_base_mod
use amg_base_prec_type
use amg_z_inner_mod
#if defined(OPENMP)
use omp_lib
#endif
implicit none
! Arguments
integer(psb_ipk_), intent(in) :: iorder
logical, intent(in) :: clean_zeros
type(psb_zspmat_type), intent(in) :: a
type(psb_desc_type), intent(in) :: desc_a
real(psb_dpk_), intent(in) :: theta
integer(psb_lpk_), allocatable, intent(out) :: ilaggr(:),nlaggr(:)
integer(psb_ipk_), intent(out) :: info
! Local variables
integer(psb_ipk_), allocatable :: neigh(:), irow(:), icol(:),&
& ideg(:), idxs(:)
integer(psb_lpk_), allocatable :: tmpaggr(:)
complex(psb_dpk_), allocatable :: val(:), diag(:)
integer(psb_ipk_) :: icnt,nlp,k,n,ia,isz,nr, nc, naggr,i,j,m, nz, ilg, ii, ip
type(psb_z_csr_sparse_mat) :: acsr
real(psb_dpk_) :: cpling, tcl
logical :: disjoint
integer(psb_ipk_) :: debug_level, debug_unit,err_act
type(psb_ctxt_type) :: ctxt
integer(psb_ipk_) :: np, me
integer(psb_ipk_) :: nrow, ncol, n_ne
integer(psb_lpk_) :: nrglob
character(len=20) :: name, ch_err
integer(psb_ipk_), save :: idx_soc1_p1=-1, idx_soc1_p2=-1, idx_soc1_p3=-1
integer(psb_ipk_), save :: idx_soc1_p0=-1
logical, parameter :: do_timings=.true.
info=psb_success_
name = 'amg_soc1_map_bld'
call psb_erractionsave(err_act)
if (psb_errstatus_fatal()) then
info = psb_err_internal_error_; goto 9999
end if
debug_unit = psb_get_debug_unit()
debug_level = psb_get_debug_level()
!
ctxt=desc_a%get_context()
call psb_info(ctxt,me,np)
nrow = desc_a%get_local_rows()
ncol = desc_a%get_local_cols()
nrglob = desc_a%get_global_rows()
if ((do_timings).and.(idx_soc1_p0==-1)) &
& idx_soc1_p0 = psb_get_timer_idx("SOC1_MAP: phase0")
if ((do_timings).and.(idx_soc1_p1==-1)) &
& idx_soc1_p1 = psb_get_timer_idx("SOC1_MAP: phase1")
if ((do_timings).and.(idx_soc1_p2==-1)) &
& idx_soc1_p2 = psb_get_timer_idx("SOC1_MAP: phase2")
if ((do_timings).and.(idx_soc1_p3==-1)) &
& idx_soc1_p3 = psb_get_timer_idx("SOC1_MAP: phase3")
nr = a%get_nrows()
nc = a%get_ncols()
allocate(ilaggr(nr),neigh(nr),ideg(nr),idxs(nr),&
& icol(nc),val(nc),stat=info)
if(info /= psb_success_) then
info=psb_err_alloc_request_
call psb_errpush(info,name,i_err=(/2*nr,izero,izero,izero,izero/),&
& a_err='integer')
goto 9999
end if
diag = a%get_diag(info)
if(info /= psb_success_) then
info=psb_err_from_subroutine_
call psb_errpush(info,name,a_err='psb_sp_getdiag')
goto 9999
end if
if (do_timings) call psb_tic(idx_soc1_p0)
call a%cp_to(acsr)
if (do_timings) call psb_toc(idx_soc1_p0)
if (clean_zeros) call acsr%clean_zeros(info)
if (iorder == amg_aggr_ord_nat_) then
!$omp parallel do private(i) schedule(static)
do i=1, nr
ilaggr(i) = -(nr+1)
idxs(i) = i
end do
!$omp end parallel do
else
!$omp parallel do private(i) schedule(static)
do i=1, nr
ilaggr(i) = -(nr+1)
ideg(i) = acsr%irp(i+1) - acsr%irp(i)
end do
!$omp end parallel do
call psb_msort(ideg,ix=idxs,dir=psb_sort_down_)
end if
if (do_timings) call psb_tic(idx_soc1_p1)
!
! Phase one: Start with disjoint groups.
!
naggr = 0
#if defined(OPENMP)
block
integer(psb_ipk_), allocatable :: bnds(:), locnaggr(:)
integer(psb_ipk_) :: myth,nths, kk
! The parallelization makes use of a locaggr(:) array; each thread
! keeps its own version of naggr, and when the loop ends, a prefix is applied
! to locnaggr to determine:
! 1. The total number of aggregaters NAGGR;
! 2. How much should each thread shift its own aggregates
! Part 2 requires to keep track of which thread defined each entry
! of ilaggr(), so that each entry can be adjusted correctly: even
! if an entry I belongs to the range BNDS(TH)>BNDS(TH+1)-1, it may have
! been set because it is strongly connected to an entry J belonging to a
! different thread.
!$omp parallel shared(bnds,idxs,locnaggr,ilaggr,nr,naggr,diag,theta,nths,info) &
!$omp private(icol,val,myth,kk)
block
integer(psb_ipk_) :: ii,nlp,k,kp,n,ia,isz, nc, i,j,m, nz, ilg, ip, rsz
integer(psb_lpk_) :: itmp
!$omp master
nths = omp_get_num_threads()
allocate(bnds(0:nths),locnaggr(0:nths+1))
locnaggr(:) = 0
bnds(0) = 1
!$omp end master
!$omp barrier
myth = omp_get_thread_num()
rsz = nr/nths
if (myth < mod(nr,nths)) rsz = rsz + 1
bnds(myth+1) = rsz
!$omp barrier
!$omp master
do i=1,nths
bnds(i) = bnds(i) + bnds(i-1)
end do
info = 0
!$omp end master
!$omp barrier
!$omp do schedule(static) private(disjoint)
do kk=0, nths-1
step1: do ii=bnds(kk), bnds(kk+1)-1
i = idxs(ii)
if (info /= 0) cycle step1
if ((i<1).or.(i>nr)) then
!$omp atomic write
info=psb_err_internal_error_
!$omp end atomic
call psb_errpush(info,name)
cycle step1
!goto 9999
end if
if (ilaggr(i) == -(nr+1)) then
nz = (acsr%irp(i+1)-acsr%irp(i))
if ((nz<0).or.(nz>size(icol))) then
!$omp atomic write
info=psb_err_internal_error_
!$omp end atomic
call psb_errpush(info,name)
cycle step1
!goto 9999
end if
icol(1:nz) = acsr%ja(acsr%irp(i):acsr%irp(i+1)-1)
val(1:nz) = acsr%val(acsr%irp(i):acsr%irp(i+1)-1)
!
! Build the set of all strongly coupled nodes
!
ip = 0
do k=1, nz
j = icol(k)
! If any of the neighbours is already assigned,
! we will not reset.
if (j>nr) cycle step1
if (ilaggr(j) > 0) cycle step1
if (abs(val(k)) > theta*sqrt(abs(diag(i)*diag(j)))) then
ip = ip + 1
icol(ip) = icol(k)
end if
enddo
!
! If the whole strongly coupled neighborhood of I is
! as yet unconnected, turn it into the next aggregate.
! Same if ip==0 (in which case, neighborhood only
! contains I even if it does not look like it from matrix)
! The fact that DISJOINT is private and not under lock
! generates a certain un-repeatability, in that between
! computing DISJOINT and assigning, another thread might
! alter the values of ILAGGR.
! However, a certain unrepeatability is already present
! because the sequence of aggregates is computed with a
! different order than in serial mode.
! In any case, even if the enteries of ILAGGR may be
! overwritten, the important thing is that each entry is
! consistent and they generate a correct aggregation map.
!
disjoint = all(ilaggr(icol(1:ip)) == -(nr+1)).or.(ip==0)
if (disjoint) then
locnaggr(kk) = locnaggr(kk) + 1
itmp = (bnds(kk)-1+locnaggr(kk))*nths+kk
if (itmp < (bnds(kk)-1+locnaggr(kk))) then
!$omp atomic update
info = max(12345678,info)
!$omp end atomic
cycle step1
end if
!$omp atomic write
ilaggr(i) = itmp
!$omp end atomic
do k=1, ip
!$omp atomic write
ilaggr(icol(k)) = itmp
!$omp end atomic
end do
end if
end if
enddo step1
end do
!$omp end do
!$omp master
naggr = sum(locnaggr(0:nths-1))
do i=1,nths
locnaggr(i) = locnaggr(i) + locnaggr(i-1)
end do
do i=nths+1,1,-1
locnaggr(i) = locnaggr(i-1)
end do
locnaggr(0) = 0
!$omp end master
!$omp barrier
!$omp do schedule(static)
do kk=0, nths-1
do ii=bnds(kk), bnds(kk+1)-1
if (ilaggr(ii) > 0) then
kp = mod(ilaggr(ii),nths)
ilaggr(ii) = (ilaggr(ii)/nths)- (bnds(kp)-1) + locnaggr(kp)
end if
end do
end do
!$omp end do
end block
!$omp end parallel
end block
if (info /= 0) then
if (info == 12345678) write(0,*) 'Overflow in encoding ILAGGR'
info=psb_err_internal_error_
call psb_errpush(info,name)
goto 9999
end if
#else
step1: do ii=1, nr
if (info /= 0) cycle
i = idxs(ii)
if ((i<1).or.(i>nr)) then
info=psb_err_internal_error_
call psb_errpush(info,name)
cycle step1
!goto 9999
end if
if (ilaggr(i) == -(nr+1)) then
nz = (acsr%irp(i+1)-acsr%irp(i))
if ((nz<0).or.(nz>size(icol))) then
info=psb_err_internal_error_
call psb_errpush(info,name)
cycle step1
!goto 9999
end if
icol(1:nz) = acsr%ja(acsr%irp(i):acsr%irp(i+1)-1)
val(1:nz) = acsr%val(acsr%irp(i):acsr%irp(i+1)-1)
!
! Build the set of all strongly coupled nodes
!
ip = 0
do k=1, nz
j = icol(k)
if ((1<=j).and.(j<=nr)) then
if (abs(val(k)) > theta*sqrt(abs(diag(i)*diag(j)))) then
ip = ip + 1
icol(ip) = icol(k)
end if
end if
enddo
!
! If the whole strongly coupled neighborhood of I is
! as yet unconnected, turn it into the next aggregate.
! Same if ip==0 (in which case, neighborhood only
! contains I even if it does not look like it from matrix)
!
disjoint = all(ilaggr(icol(1:ip)) == -(nr+1)).or.(ip==0)
if (disjoint) then
naggr = naggr + 1
do k=1, ip
ilaggr(icol(k)) = naggr
end do
ilaggr(i) = naggr
end if
endif
enddo step1
#endif
if (debug_level >= psb_debug_outer_) then
write(debug_unit,*) me,' ',trim(name),&
& ' Check 1:',naggr,count(ilaggr(1:nr) == -(nr+1)), count(ilaggr(1:nr)>0),&
& count(ilaggr(1:nr) == -(nr+1))+count(ilaggr(1:nr)>0),nr
end if
if (do_timings) call psb_toc(idx_soc1_p1)
if (do_timings) call psb_tic(idx_soc1_p2)
!
! Phase two: join the neighbours
!
!$omp workshare
tmpaggr = ilaggr
!$omp end workshare
!$omp parallel do schedule(static) shared(tmpaggr,ilaggr,nr,naggr,diag,theta)&
!$omp private(ii,i,j,k,nz,icol,val,ip,cpling)
step2: do ii=1,nr
i = idxs(ii)
if (ilaggr(i) == -(nr+1)) then
nz = (acsr%irp(i+1)-acsr%irp(i))
if (nz == 1) cycle step2
icol(1:nz) = acsr%ja(acsr%irp(i):acsr%irp(i+1)-1)
val(1:nz) = acsr%val(acsr%irp(i):acsr%irp(i+1)-1)
!
! Find the most strongly connected neighbour that is
! already aggregated, if any, and join its aggregate
!
cpling = dzero
ip = 0
do k=1, nz
j = icol(k)
if ((1<=j).and.(j<=nr)) then
if ((abs(val(k)) > theta*sqrt(abs(diag(i)*diag(j))))&
& .and. (tmpaggr(j) > 0).and. (abs(val(k)) > cpling)) then
ip = k
cpling = abs(val(k))
end if
end if
enddo
if (ip > 0) then
ilaggr(i) = ilaggr(icol(ip))
end if
end if
end do step2
!$omp end parallel do
if (do_timings) call psb_toc(idx_soc1_p2)
if (debug_level >= psb_debug_outer_) then
write(debug_unit,*) me,' ',trim(name),&
& ' Check 1.5:',naggr,count(ilaggr(1:nr) == -(nr+1)), count(ilaggr(1:nr)>0),&
& count(ilaggr(1:nr) == -(nr+1))+count(ilaggr(1:nr)>0),nr
end if
if (do_timings) call psb_tic(idx_soc1_p3)
!
! Phase three: sweep over leftovers, if any
!
step3: do ii=1,nr
i = idxs(ii)
if (ilaggr(i) < 0) then
nz = (acsr%irp(i+1)-acsr%irp(i))
if (nz == 1) cycle step3
icol(1:nz) = acsr%ja(acsr%irp(i):acsr%irp(i+1)-1)
val(1:nz) = acsr%val(acsr%irp(i):acsr%irp(i+1)-1)
!
! Find its strongly connected neighbourhood not
! already aggregated, and make it into a new aggregate.
!
cpling = dzero
ip = 0
do k=1, nz
j = icol(k)
if ((1<=j).and.(j<=nr)) then
if ((abs(val(k)) > theta*sqrt(abs(diag(i)*diag(j))))&
& .and. (ilaggr(j) < 0)) then
ip = ip + 1
icol(ip) = icol(k)
end if
end if
enddo
if (ip > 0) then
naggr = naggr + 1
ilaggr(i) = naggr
do k=1, ip
ilaggr(icol(k)) = naggr
end do
else
!
! This should not happen: we did not even connect with ourselves,
! but it's not a singleton.
!
naggr = naggr + 1
ilaggr(i) = naggr
end if
end if
end do step3
! Any leftovers?
!$omp parallel do schedule(static) shared(ilaggr,info)&
!$omp private(ii,i,j,k,nz,icol,val,ip)
do i=1, nr
if (info /= 0) cycle
if (ilaggr(i) < 0) then
nz = (acsr%irp(i+1)-acsr%irp(i))
if (nz == 1) then
! Mark explicitly as a singleton so that
! it will be ignored in map_to_tprol.
! Need to use -(nrglob+nr) to make sure
! it's still negative when shifted and combined with
! other processes.
ilaggr(i) = -(nrglob+nr)
else
!$omp atomic write
info=psb_err_internal_error_
!$omp end atomic
call psb_errpush(info,name,a_err='Fatal error: non-singleton leftovers')
cycle
endif
end if
end do
!$omp end parallel do
if (info /= 0) goto 9999
if (do_timings) call psb_toc(idx_soc1_p3)
if (naggr > ncol) then
info=psb_err_internal_error_
call psb_errpush(info,name,a_err='Fatal error: naggr>ncol')
goto 9999
end if
call psb_realloc(ncol,ilaggr,info)
if (info /= psb_success_) then
info=psb_err_from_subroutine_
ch_err='psb_realloc'
call psb_errpush(info,name,a_err=ch_err)
goto 9999
end if
allocate(nlaggr(np),stat=info)
if (info /= psb_success_) then
info=psb_err_alloc_request_
call psb_errpush(info,name,i_err=(/np,izero,izero,izero,izero/),&
& a_err='integer')
goto 9999
end if
nlaggr(:) = 0
nlaggr(me+1) = naggr
call psb_sum(ctxt,nlaggr(1:np))
if (debug_level >= psb_debug_outer_) then
write(debug_unit,*) me,' ',trim(name),&
& ' Check 2:',naggr,count(ilaggr(1:nr) == -(nr+1)), count(ilaggr(1:nr)>0),&
& count(ilaggr(1:nr) == -(nr+1))+count(ilaggr(1:nr)>0),nr
end if
call acsr%free()
call psb_erractionrestore(err_act)
return
9999 call psb_error_handler(err_act)
return
end subroutine amg_z_soc1_map_bld