New structure for A2A and graph_fnd_owner

New implementation for A2A: use mpi_allgather and mpi_reduce_scatter,
with two variants: one for variable inputs, one for fixed size
inputs.
Modified graph_fnd_owner to pass padded and uniform sized input to
A2A.

base/internals/psi_a2a_fnd_owner.F90

@@ -47,7 +47,7 @@
 ! so it goes for an all-to-all by building an auxiliary neighbours list and
 ! reusing the neighbour version.
 ! 
-subroutine psi_a2a_fnd_owner(idx,iprc,idxmap,info)
+subroutine psi_a2a_fnd_owner(idx,iprc,idxmap,info,samesize)
   use psb_serial_mod
   use psb_const_mod
   use psb_error_mod
@@ -66,16 +66,22 @@ subroutine psi_a2a_fnd_owner(idx,iprc,idxmap,info)
   integer(psb_ipk_), allocatable, intent(out) ::  iprc(:)
   class(psb_indx_map), intent(in) :: idxmap
   integer(psb_ipk_), intent(out)  :: info
+  logical, intent(in), optional   :: samesize
 
 
   integer(psb_ipk_), allocatable :: tmpadj(:)
-  integer(psb_mpk_) :: icomm, minfo, iictxt
+  integer(psb_lpk_), allocatable :: rmtidx(:)
-  integer(psb_ipk_) :: i,n_row,n_col,err_act,nv
+  integer(psb_ipk_), allocatable :: tproc(:), lclidx(:)
+  integer(psb_mpk_), allocatable :: hsz(:),hidx(:), sdidx(:), rvidx(:),&
+       & sdsz(:), rvsz(:), sdhd(:), rvhd(:), p2pstat(:,:)
+  integer(psb_mpk_) :: icomm, minfo, iictxt,nv
+  integer(psb_ipk_) :: i,n_row,n_col,err_act,gsz
   integer(psb_lpk_) :: mglob, ih
   integer(psb_ipk_) :: ictxt,np,me, nresp
   logical, parameter :: use_psi_adj=.true.
   real(psb_dpk_)     :: t0, t1, t2, t3, t4, tamx, tidx
   character(len=20)  :: name
+  logical            :: samesize_
 
   info = psb_success_
   name = 'psi_a2a_fnd_owner'
@@ -101,22 +107,94 @@ subroutine psi_a2a_fnd_owner(idx,iprc,idxmap,info)
     goto 9999      
   end if
 
+  if (present(samesize)) then
+    samesize_ = samesize
+  else
+    samesize_ = .false.
+  end if
+  nv = size(idx)
+  ! write(0,*) me,name,' :',use_psi_adj,samesize_,nv
   if (use_psi_adj) then 
     !
     ! Reuse the adjcncy version by tricking it with an adjcncy list
     ! that contains everybody but ME. 
     !
-    nv = size(idx)
     call psb_realloc(np-1,tmpadj,info)
     tmpadj(1:me) = [(i,i=0,me-1)]
     tmpadj(me+1:np-1) = [(i,i=me+1,np-1)]
     call  psi_adjcncy_fnd_owner(idx,iprc,tmpadj,idxmap,info)
+
   else
-    !
+    if (samesize_) then
-    ! 1. allgetherv
+      !
-    ! 2. local conversion
+      ! Variant when IDX is guaranteed to have the same size on all
-    ! 3. reduce_scatter
+      ! processes. To be tested for performance: is it worth it?
-    !
+      ! Probably yes. 
+      !
+      gsz = nv*np
+      Allocate(rmtidx(gsz),lclidx(gsz),iprc(nv),stat=info)
+      if (info /= psb_success_) then 
+        call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate')
+        goto 9999      
+      end if
+      call mpi_allgather(idx,nv,psb_mpi_lpk_,rmtidx,nv,psb_mpi_lpk_,icomm,minfo)
+      call idxmap%g2l(rmtidx(1:gsz),lclidx(1:gsz),info,owned=.true.)
+      !
+      ! Reuse lclidx to encode owning process
+      !
+      do i=1, gsz
+        if ((1<=lclidx(i)).and.(lclidx(i)<=n_row)) then
+          lclidx(i) = me
+        else
+          lclidx(i) = -1
+        end if
+      end do
+      call mpi_reduce_scatter_block(lclidx,iprc,nv,psb_mpi_ipk_,mpi_max,icomm,minfo)
+      
+    else
+      !
+      ! 1. allgetherv
+      ! 2. local conversion
+      ! 3. reduce_scatter
+      !
+      !
+      ! The basic idea is very simple. 
+      ! First we collect (to all) all the requests. 
+      Allocate(hidx(np+1),hsz(np),stat=info)
+      if (info /= psb_success_) then 
+        call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate') 
+        goto 9999      
+      end if
+
+      call mpi_allgather(nv,1,psb_mpi_mpk_,hsz,1,psb_mpi_mpk_,icomm,minfo)
+      hidx(1)   = 0
+      do i=1, np
+        hidx(i+1) = hidx(i) + hsz(i)
+      end do
+      gsz = hidx(np+1)
+      Allocate(rmtidx(gsz),lclidx(gsz),iprc(nv),stat=info)
+      if (info /= psb_success_) then 
+        call psb_errpush(psb_err_from_subroutine_,name,a_err='Allocate')
+        goto 9999      
+      end if
+
+      call mpi_allgatherv(idx,hsz(me+1),psb_mpi_lpk_,&
+           & rmtidx,hsz,hidx,psb_mpi_lpk_,&
+           & icomm,minfo)
+
+      call idxmap%g2l(rmtidx(1:gsz),lclidx(1:gsz),info,owned=.true.)
+      !
+      ! Reuse lclidx to encode owning process
+      !
+      do i=1, gsz
+        if ((1<=lclidx(i)).and.(lclidx(i)<=n_row)) then
+          lclidx(i) = me
+        else
+          lclidx(i) = -1
+        end if
+      end do
+      call mpi_reduce_scatter(lclidx,iprc,hsz,psb_mpi_ipk_,mpi_max,icomm,minfo)
+    end if
   end if
 
   call psb_erractionrestore(err_act)

base/internals/psi_graph_fnd_owner.F90

@@ -101,8 +101,8 @@ subroutine psi_graph_fnd_owner(idx,iprc,idxmap,info)
   integer(psb_ipk_), allocatable :: tprc(:), tsmpl(:), ladj(:)  
   integer(psb_mpk_) :: icomm, minfo, iictxt
   integer(psb_ipk_) :: i,n_row,n_col,err_act,ip,j,ipnt, nsampl_out,&
-       & nv, n_answers, n_rest, nsampl_in, locr_max, &
+       & nv, n_answers, nreqst, nsampl_in, locr_max, &
-       & nrest_max, nadj, maxspace, mxnsin
+       & nreqst_max, nadj, maxspace, mxnsin
   integer(psb_lpk_) :: mglob, ih
   integer(psb_ipk_) :: ictxt,np,me, nresp
   integer(psb_ipk_), parameter :: nt=4
@@ -164,15 +164,19 @@ subroutine psi_graph_fnd_owner(idx,iprc,idxmap,info)
   nadj = psb_size(ladj)
   ! This makes ladj allocated with size 0 just in case 
   call psb_realloc(nadj,ladj,info)
-  n_rest    = nv - n_answers
+  !
-  nrest_max = n_rest
+  ! Throughout the subroutine, nreqst is the number of local inquiries
+  ! that have not been answered yet
+  ! 
+  nreqst     = nv - n_answers
+  nreqst_max = nreqst
 
   !
   ! Choice of maxspace should be adjusted to account for a default
   ! "sensible" size and/or a user-specified value
   !
   tmpv(1) = nadj
-  tmpv(2) = nrest_max
+  tmpv(2) = nreqst_max
   tmpv(3) = n_row
   tmpv(4) = psb_cd_get_maxspace()
   call psb_max(ictxt,tmpv)
@@ -187,12 +191,12 @@ subroutine psi_graph_fnd_owner(idx,iprc,idxmap,info)
     ! Do a preliminary run on the user-defined adjacency lists
     !
     if (trace.and.(me == 0)) write(0,*) ' Initial sweep on user-defined topology'
-    nsampl_in = min(n_rest,max(1,(maxspace+max(1,nadj)-1))/(max(1,nadj)))
+    nsampl_in = min(nreqst,max(1,(maxspace+max(1,nadj)-1))/(max(1,nadj)))
     call psi_adj_fnd_sweep(idx,iprc,ladj,idxmap,nsampl_in,n_answers)  
     call idxmap%xtnd_p_adjcncy(ladj) 
-    n_rest    = nv - n_answers
+    nreqst     = nv - n_answers
-    nrest_max = n_rest
+    nreqst_max = nreqst
-    call psb_max(ictxt,nrest_max)
+    call psb_max(ictxt,nreqst_max)
     if (trace.and.(me == 0)) write(0,*) ' After initial sweep:',nrest_max
   end if
   if (do_timings) call psb_toc(idx_sweep0)
@@ -208,28 +212,32 @@ subroutine psi_graph_fnd_owner(idx,iprc,idxmap,info)
     !    sample query is then sent to all processes
     !    
     ! if (trace.and.(me == 0)) write(0,*) 'Looping in graph_fnd_owner: ', nrest_max
-    nsampl_in = min(n_rest,max(1,(maxspace+np-1)/np))
+    nsampl_in = psb_cd_get_samplesize()
-    !nsampl_in = min(n_rest,32)
+    nsampl_in = min(max(1,(maxspace+np-1)/np),nsampl_in)
     !
     ! Choose a sample, should it be done in this simplistic way?
     ! Note: nsampl_in is a hint, not an absolute, hence nsampl_out
     !
     ipnt = 1
-!!$      write(0,*) me,' Into first sampling ',nsampl_in
+    call psi_get_sample(ipnt, idx,iprc,tidx,tsmpl,nsampl_in,nsampl_out, pad=.true.)      
-    call psi_get_sample(ipnt, idx,iprc,tidx,tsmpl,nsampl_in,nsampl_out)      
     nsampl_in = min(nsampl_out,nsampl_in)
 !!$      write(0,*) me,' From first sampling ',nsampl_in
     ! 
     ! 2. Do a search on all processes; this is supposed to find
     !    the owning process for all inputs;
     !    
-    call psi_a2a_fnd_owner(tidx(1:nsampl_in),tprc,idxmap,info)
+    call psi_a2a_fnd_owner(tidx(1:nsampl_in),tprc,idxmap,info, samesize=.true.)
+    !
+    ! We might have padded when looking for owners, so the actual samples
+    ! could be less than they appear. Should be explained better.
+    !
+    nsampl_in = min(nreqst,nsampl_in)
     call psi_cpy_out(iprc,tprc,tsmpl,nsampl_in,nsampl_out)      
     if (nsampl_out /= nsampl_in) then 
       write(0,*) me,'Warning: indices not found by a2a_fnd_owner ',nsampl_out,nsampl_in
     end if
     n_answers = n_answers + nsampl_out
-    n_rest    = nv - n_answers
+    nreqst    = nv - n_answers
     !
     ! 3. Extract the resulting adjacency list and add it to the
     !    indxmap;
@@ -246,16 +254,16 @@ subroutine psi_graph_fnd_owner(idx,iprc,idxmap,info)
     !    Need to set up a proper loop here to have a complete
     !    sweep over the input vector. Done inside adj_fnd_sweep. 
     !
-!!$      write(0,*) me,' After a2a ',n_rest
+!!$      write(0,*) me,' After a2a ',nreqst
-    nsampl_in = min(n_rest,max(1,(maxspace+max(1,nadj)-1))/(max(1,nadj)))
+    nsampl_in = min(nreqst,max(1,(maxspace+max(1,nadj)-1))/(max(1,nadj)))
     mxnsin = nsampl_in
     call psb_max(ictxt,mxnsin)
 !!$      write(0,*) me, ' mxnsin ',mxnsin
     if (mxnsin>0) call psi_adj_fnd_sweep(idx,iprc,ladj,idxmap,nsampl_in,n_answers)  
     call idxmap%xtnd_p_adjcncy(ladj) 
 
-    n_rest    = nv - n_answers
+    nreqst    = nv - n_answers
-    nrest_max = n_rest
+    nrest_max = nreqst
     call psb_max(ictxt,nrest_max)
     if (trace.and.(me == 0)) write(0,*) ' fnd_owner_loop remaining:',nrest_max
     if (do_timings) call psb_toc(idx_loop_neigh)    
@@ -270,16 +278,23 @@ subroutine psi_graph_fnd_owner(idx,iprc,idxmap,info)
 
 contains
 
-  subroutine psi_get_sample(ipntidx,idx,iprc,tidx,tsmpl,ns_in,ns_out)      
+  subroutine psi_get_sample(ipntidx,idx,iprc,tidx,tsmpl,ns_in,ns_out,pad)      
     implicit none
     integer(psb_ipk_), intent(inout) :: ipntidx
     integer(psb_lpk_), intent(in)    :: idx(:)
     integer(psb_ipk_), intent(in)    :: ns_in, iprc(:)
     integer(psb_lpk_), intent(out)   :: tidx(:)
     integer(psb_ipk_), intent(out)   :: tsmpl(:), ns_out
+    logical, intent(in), optional    :: pad
     !
-    integer(psb_ipk_) :: nv, ns
+    integer(psb_ipk_) :: nv, ns, k
+    logical :: pad_
 
+    if (present(pad)) then
+      pad_ = pad
+    else
+      pad_ = .false.
+    end if
     nv = size(idx)
     !
     ! Choose a sample, should it be done in this simplistic way? 
@@ -302,6 +317,13 @@ contains
       ipntidx = ipntidx + 1
       if (ns_out >= ns) exit
     end do
+    if (pad_) then
+      do k = ns_out+1, ns
+        tsmpl(k) = -1
+        tidx(k)  = -1
+      end do
+      ns_out = ns
+    end if
 
   end subroutine psi_get_sample
 

base/modules/desc/psb_desc_mod.F90

@@ -285,14 +285,6 @@ module psb_desc_mod
     module procedure psb_cdfree
   end interface psb_free
 
-  interface psb_cd_set_maxspace
-    module procedure  psb_cd_set_maxspace
-  end interface psb_cd_set_maxspace
-
-  interface psb_cd_get_maxspace
-    module procedure  psb_cd_get_maxspace
-  end interface psb_cd_get_maxspace
-
   interface psb_cd_set_large_threshold    
     module procedure  psb_i_cd_set_large_threshold
   end interface psb_cd_set_large_threshold
@@ -310,7 +302,6 @@ module psb_desc_mod
 
 
   integer(psb_lpk_), private, save :: cd_large_threshold = psb_default_large_threshold
-  integer(psb_ipk_), private, save :: cd_maxspace        = -1
 
 
 contains 
@@ -363,21 +354,6 @@ contains
     val  = cd_large_threshold 
   end function psb_cd_get_large_threshold
   
-
-  subroutine psb_cd_set_maxspace(ith)
-    implicit none 
-    integer(psb_ipk_), intent(in) :: ith
-    if (ith > 0) then 
-      cd_maxspace = ith
-    end if
-  end subroutine psb_cd_set_maxspace
-
-  function  psb_cd_get_maxspace() result(val)
-    implicit none 
-    integer(psb_ipk_) :: val
-    val  = cd_maxspace
-  end function psb_cd_get_maxspace
-  
   function  psb_cd_is_large_size(m) result(val)
     use psb_penv_mod
 

base/modules/desc/psb_indx_map_mod.f90

@@ -29,7 +29,7 @@
 !    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 !    POSSIBILITY OF SUCH DAMAGE.
 !   
-!!$  
+! 
 !
 !
 ! package: psb_indx_map_mod
@@ -278,13 +278,14 @@ module psb_indx_map_mod
   end interface
 
   interface 
-    subroutine psi_a2a_fnd_owner(idx,iprc,idxmap,info)
+    subroutine psi_a2a_fnd_owner(idx,iprc,idxmap,info,samesize)
       import :: psb_indx_map, psb_ipk_, psb_lpk_
       implicit none 
       integer(psb_lpk_), intent(in)      :: idx(:)
       integer(psb_ipk_), allocatable, intent(out) ::  iprc(:)
       class(psb_indx_map), intent(in)    :: idxmap
       integer(psb_ipk_), intent(out)     :: info
+      logical, intent(in), optional      :: samesize
     end subroutine psi_a2a_fnd_owner
   end interface
 
@@ -311,6 +312,25 @@ module psb_indx_map_mod
     end subroutine psi_graph_fnd_owner
   end interface
 
+  interface psb_cd_set_maxspace
+    module procedure  psb_cd_set_maxspace
+  end interface psb_cd_set_maxspace
+
+  interface psb_cd_get_maxspace
+    module procedure  psb_cd_get_maxspace
+  end interface psb_cd_get_maxspace
+
+  interface psb_cd_set_samplesize
+    module procedure  psb_cd_set_samplesize
+  end interface psb_cd_set_samplesize
+
+  interface psb_cd_get_samplesize
+    module procedure  psb_cd_get_samplesize
+  end interface psb_cd_get_samplesize
+
+  integer(psb_ipk_), private, save :: cd_maxspace   = -1
+  integer(psb_ipk_), private, save :: samplesize    = 32
+  
   integer, parameter :: psi_symm_flag_norv_ = 0
   integer, parameter :: psi_symm_flag_inrv_ = 1
   interface psi_symm_dep_list
@@ -364,6 +384,35 @@ contains
     end select
   end function psi_get_adj_alg_fmt
 
+  subroutine psb_cd_set_maxspace(ith)
+    implicit none 
+    integer(psb_ipk_), intent(in) :: ith
+    if (ith > 0) then 
+      cd_maxspace = ith
+    end if
+  end subroutine psb_cd_set_maxspace
+
+  function  psb_cd_get_maxspace() result(val)
+    implicit none 
+    integer(psb_ipk_) :: val
+    val  = cd_maxspace
+  end function psb_cd_get_maxspace
+ 
+
+  subroutine psb_cd_set_samplesize(ith)
+    implicit none 
+    integer(psb_ipk_), intent(in) :: ith
+    if (ith > 0) then 
+      samplesize = ith
+    end if
+  end subroutine psb_cd_set_samplesize
+
+  function  psb_cd_get_samplesize() result(val)
+    implicit none 
+    integer(psb_ipk_) :: val
+    val  = samplesize
+  end function psb_cd_get_samplesize
+ 
   
   !> 
   !! \memberof psb_indx_map