adjcncy_fnd_owner with irecv

Implement adjcncy_fnd_owner with irecv to improve performance instead
of psb_snd/psb_rcv. To be fully debugged.

base/internals/psi_adjcncy_fnd_owner.F90

@@ -62,13 +62,14 @@ subroutine psi_adjcncy_fnd_owner(idx,iprc,adj,idxmap,info)
   integer(psb_lpk_), allocatable :: rmtidx(:)
   integer(psb_ipk_), allocatable :: tproc(:), lclidx(:)
   integer(psb_mpk_), allocatable :: hsz(:),hidx(:), &
-       & sdsz(:), rvsz(:)
+       & sdsz(:), rvsz(:), sdhd(:), rvhd(:), p2pstat(:,:)
+  integer(psb_mpk_) :: prc, p2ptag, iret
   integer(psb_mpk_) :: icomm, minfo, iictxt
   integer(psb_ipk_) :: i,n_row,n_col,err_act,hsize,ip,isz,j, k,&
        & last_ih, last_j, nidx, nrecv, nadj
   integer(psb_lpk_) :: mglob, ih
   integer(psb_ipk_) :: ictxt,np,me
-  logical, parameter  :: gettime=.false.
+  logical, parameter  :: gettime=.false., new_impl=.true.
   real(psb_dpk_)      :: t0, t1, t2, t3, t4, tamx, tidx
   character(len=20)   :: name
 
@@ -110,6 +111,125 @@ subroutine psi_adjcncy_fnd_owner(idx,iprc,adj,idxmap,info)
   iprc = -1
   ! write(0,*) me,name,' Going through ',nidx,nadj
 
+  if (new_impl) then
+    !
+    ! First simple minded version with auxiliary arrays
+    ! dimensioned on NP.
+    ! Could it be improved with a loop based on the maximum length
+    ! of adj(:) ???
+    !    
+    Allocate(hidx(0:np),hsz(np),sdsz(0:np-1),rvsz(0:np-1),&
+         & sdhd(0:np-1), rvhd(0:np-1), p2pstat(mpi_status_size,0:np-1),&
+         & stat=info)
+    sdhd(:) = mpi_request_null
+    rvhd(:) = mpi_request_null
+    !
+    ! First, send sizes according to adjcncy list
+    !
+    sdsz = 0 
+    do j=1, nadj
+      sdsz(adj(j)) = nidx
+    end do
+    !write(0,*)me,' Check on sizes into a2a:',adj(:),nadj,':',sdsz(:)
+
+    call mpi_alltoall(sdsz,1,psb_mpi_mpk_,&
+         & rvsz,1,psb_mpi_mpk_,icomm,minfo)
+    hidx(0) = 0
+    do i=0, np-1
+      hidx(i+1) = hidx(i) + rvsz(i)
+    end do
+    hsize = hidx(np)
+    ! write(0,*)me,' Check on sizes from a2a:',hsize,rvsz(:)
+    !
+    ! Second, allocate buffers and exchange data
+    !
+    Allocate(rmtidx(hsize),lclidx(hsize),tproc(max(hsize,nidx)),stat=info)
+
+    if (info /= psb_success_) then 
+      call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate')
+      goto 9999      
+    end if
+    do i = 0, np-1
+      if (rvsz(i)>0) then
+        ! write(0,*) me, ' First receive from ',i,rvsz(i)
+        call psb_get_rank(prc,ictxt,i)        
+        p2ptag = psb_long_swap_tag
+        write(0,*) me, ' Posting first receive from ',i,rvsz(i),prc           
+        call mpi_irecv(rmtidx(hidx(i)+1),rvsz(i),&
+             & psb_mpi_lpk_,prc,&
+             & p2ptag, icomm,rvhd(i),iret)
+      end if
+    end do
+    do j=1, nadj
+      if (nidx > 0) then
+        !call psb_snd(ictxt,idx(1:nidx),adj(j))
+        call psb_get_rank(prc,ictxt,adj(j))        
+        p2ptag = psb_long_swap_tag
+        write(0,*) me, ' First send to ',adj(j),nidx, prc
+        call mpi_send(idx,nidx,&
+             & psb_mpi_lpk_,prc,&
+             & p2ptag, icomm,iret)
+      end if
+    end do
+!!$    do i = 0, np-1
+!!$      if (rvsz(i)>0) then
+!!$        ! write(0,*) me, ' First receive from ',i,rvsz(i)           
+!!$        call psb_rcv(ictxt,rmtidx(hidx(i)+1:hidx(i)+rvsz(i)),i)
+!!$      end if
+!!$    end do
+    call mpi_waitall(np,rvhd,p2pstat,iret)
+    
+    !
+    ! Third, compute local answers
+    !
+    call idxmap%g2l(rmtidx(1:hsize),lclidx(1:hsize),info,owned=.true.)
+    do i=1, hsize
+      tproc(i) = -1
+      if ((0 < lclidx(i)).and. (lclidx(i) <= n_row)) tproc(i) = me
+    end do
+    !
+    ! At this point we can reuse lclidx to receive messages
+    !
+    rvhd(:) = mpi_request_null
+    do j=1, nadj
+      !write(0,*) me, ' First send to ',adj(j),nidx
+      if (nidx > 0) then
+        !call psb_snd(ictxt,idx(1:nidx),adj(j))
+        call psb_get_rank(prc,ictxt,adj(j))        
+        p2ptag = psb_int_swap_tag
+        write(0,*) me, ' Posting second receive from ',adj(j),nidx, prc
+        call mpi_irecv(lclidx((j-1)*nidx+1),nidx, &
+             & psb_mpi_ipk_,prc,&
+             & p2ptag, icomm,rvhd(j),iret)
+      end if
+    end do
+    
+    !
+    ! Fourth, send data back; 
+    !
+    do i = 0, np-1
+      if (rvsz(i)>0) then
+        !call psb_snd(ictxt,tproc(hidx(i)+1:hidx(i)+rvsz(i)),i)
+        call psb_get_rank(prc,ictxt,i)        
+        p2ptag = psb_int_swap_tag
+        write(0,*) me, ' Second send to ',i,rvsz(i), prc
+        call mpi_send(tproc(hidx(i)+1),rvsz(i),&
+             & psb_mpi_ipk_,prc,&
+             & p2ptag, icomm,iret)
+      end if
+    end do
+    !
+    ! Fifth: receive and combine. MAX works because default
+    ! answer is -1. 
+    !
+    call mpi_waitall(np,rvhd,p2pstat,iret)    
+    do j = 1, nadj
+      !write(0,*) me, ' Second receive from ',adj(j), nidx          
+      !if (nidx > 0) call psb_rcv(ictxt,tproc(1:nidx),adj(j))
+      iprc(1:nidx) = max(iprc(1:nidx), lclidx((j-1)*nidx+1:(j-1)*nidx+nidx))
+    end do
+
+  else
     Allocate(hidx(0:np),hsz(np),&
          & sdsz(0:np-1),rvsz(0:np-1),stat=info)
     !
@@ -176,7 +296,7 @@ subroutine psi_adjcncy_fnd_owner(idx,iprc,adj,idxmap,info)
       if (nidx > 0) call psb_rcv(ictxt,tproc(1:nidx),adj(j))
       iprc(1:nidx) = max(iprc(1:nidx), tproc(1:nidx))
     end do
-  
+  end if
   call psb_erractionrestore(err_act)
   return