Remove unneeded barriers.

src/comms_module.f90

@@ -142,8 +142,6 @@ subroutine Mquest_start_send(a_b_c,b,nreq,myid,mx_nponn,sends)
           endif
        enddo ! Partitions to send
     enddo ! Nodes to send to
-    ! Synchronise with other nodes
-    call MPI_Barrier(MPI_COMM_WORLD,ierr)
     return
   end subroutine Mquest_start_send
 !!***

src/generic_comms.f90

@@ -287,13 +287,17 @@ subroutine init_comms(myid,number_of_procs)
 
     ! Local variables
     integer :: ierr
+    character(len=MPI_MAX_PROCESSOR_NAME) :: pname
+    integer :: rlen
 
     call MPI_INIT(ierr)
     if(ierr.ne.0) write(io_lun,*) 'ierr is ',ierr
     call MPI_COMM_RANK( MPI_COMM_WORLD, myid, ierr )
     call MPI_COMM_SIZE( MPI_COMM_WORLD, number_of_procs, ierr )
+    call MPI_GET_PROCESSOR_NAME(pname, rlen, ierr)
     inode  = myid+1
     ionode = 1
+    write(io_lun,*) 'Process ',myid,' is running on node ',pname
     if(inode==ionode) open(unit=warning_lun, file='Conquest_warnings')
     call mtmini()
     return

src/multiply_module.f90

@@ -244,15 +244,8 @@ subroutine mat_mult(myid,a,lena,b,lenb,c,lenc,a_b_c,debug)
        index_rec = mod(kpart,2) + 1
        index_comp = mod(kpart+1,2) + 1
 
-       ! Check that previous partition data have been received before starting computation
-       if (kpart.gt.2) then
-          if (request(1,index_comp).ne.MPI_REQUEST_NULL) &
-               call MPI_Wait(request(1,index_comp),MPI_STATUSES_IGNORE,ierr)
-          if (request(2,index_comp).ne.MPI_REQUEST_NULL) &
-               call MPI_Wait(request(2,index_comp),MPI_STATUSES_IGNORE,ierr)
-       end if
-
-       ! If that previous partition was a periodic one, copy over arrays from previous index
+       ! If the previous partition was a periodic one, copy over arrays from previous index.
+       ! No need to wait for communication to finish.
        if(.not.new_partition(index_comp)) then
           part_array(:,index_comp) = part_array(:,index_rec)
           n_cont(index_comp) = n_cont(index_rec)
@@ -261,6 +254,23 @@ subroutine mat_mult(myid,a,lena,b,lenb,c,lenc,a_b_c,debug)
           lenb_rem(index_comp) = lenb_rem(index_rec)
        end if
 
+        ! Receive the data from the current partition - non-blocking
+        if (kpart.lt.a_b_c%ahalo%np_in_halo+1) then
+           call do_comms(k_off(index_rec), kpart, part_array(:,index_rec), n_cont(index_rec), ilen2(index_rec), &
+                a_b_c, b, recv_part, b_rem(index_rec)%values, &
+                lenb_rem(index_rec), myid, ncover_yz, new_partition(index_rec), .true., request(:,index_rec))
+        end if
+
+       ! Check that previous partition data have been received before starting computation
+       if (kpart.gt.2) then
+          if (request(1,index_comp).ne.MPI_REQUEST_NULL) &
+               call MPI_Wait(request(1,index_comp),MPI_STATUSES_IGNORE,ierr)
+          if (request(2,index_comp).ne.MPI_REQUEST_NULL) &
+               call MPI_Wait(request(2,index_comp),MPI_STATUSES_IGNORE,ierr)
+          if (request(1,index_comp).ne.MPI_REQUEST_NULL .or. request(2,index_comp).ne.MPI_REQUEST_NULL) &
+             call cq_abort('mat_mult: error freeing MPI_request after MPI_Wait')
+       end if
+
         ! Now point the _rem variables at the appropriate parts of
         ! the array where we have received the data
         offset = 0
@@ -283,13 +293,6 @@ subroutine mat_mult(myid,a,lena,b,lenb,c,lenc,a_b_c,debug)
         call end_part_comms(myid,n_cont(index_comp),nbnab_rem, &
              ibind_rem,npxyz_rem,ibpart_rem,ncover_yz,a_b_c%gcs%ncoverz)
 
-        ! Receive the data from the current partition - non-blocking
-        if (kpart.lt.a_b_c%ahalo%np_in_halo+1) then
-           call do_comms(k_off(index_rec), kpart, part_array(:,index_rec), n_cont(index_rec), ilen2(index_rec), &
-                a_b_c, b, recv_part, b_rem(index_rec)%values, &
-                lenb_rem(index_rec), myid, ncover_yz, new_partition(index_rec), .true., request(:,index_rec))
-        end if
-
        ! Omp master doesn't include an implicit barrier. We want master
        ! to be finished with comms before calling the multiply kernels
        ! hence the explicit barrier
@@ -310,7 +313,6 @@ subroutine mat_mult(myid,a,lena,b,lenb,c,lenc,a_b_c,debug)
                a_b_c%ltrans,a_b_c%bmat(1)%mx_abs,a_b_c%parts%mx_mem_grp, &
                a_b_c%prim%mx_iprim, lena, lenb_rem(index_comp), lenc)
        end if
-       !$omp barrier
     end do main_loop    
     !$omp end parallel
 
@@ -330,30 +332,25 @@ subroutine mat_mult(myid,a,lena,b,lenb,c,lenc,a_b_c,debug)
           !write(io_lun,*) 'Send done ',i,myid
        end do
     end if
-    call my_barrier
     call start_timer(tmr_std_allocation)
     deallocate(nreqs,STAT=stat)
     if(stat/=0) call cq_abort('mat_mult: error deallocating nreqs')
     call stop_timer(tmr_std_allocation)
-    call my_barrier
     ! --- for type 2, make backward local transpose of A-matrix -----------
     if(a_b_c%mult_type.eq.2) then
        invdir=1
        call loc_trans( a_b_c%ltrans, a_b_c%ahalo,a,lena,atrans,lena,invdir)
     end if
-    call my_barrier
     call start_timer(tmr_std_allocation)
     deallocate(atrans,STAT=stat)
     if(stat/=0) call cq_abort('mat_mult: error deallocating atrans')
     call stop_timer(tmr_std_allocation)
-    call my_barrier
     call start_timer(tmr_std_allocation)
     deallocate(ibpart_rem,STAT=stat)
     if(stat/=0) call cq_abort('mat_mult: error deallocating ibpart_rem')
     deallocate(recv_part,STAT=stat)
     if(stat/=0) call cq_abort('mat_mult: error deallocating recv_part')
     call stop_timer(tmr_std_allocation)
-    call my_barrier
     !deallocate(b_rem,STAT=stat)
     !if(stat/=0) call cq_abort('mat_mult: error deallocating b_rem')
     !call my_barrier
@@ -627,9 +624,9 @@ subroutine do_comms(k_off, kpart, part_array, n_cont, ilen2, a_b_c, b, recv_part
             n_cont,part_array,a_b_c%bindex,b_rem,lenb_rem,b,myid,ilen2,&
             mx_msg_per_part,a_b_c%parts,a_b_c%prim,a_b_c%gcs,(recv_part(nnode)-1)*2,do_nonb,request)
     end if
-       
-       k_off=a_b_c%ahalo%lab_hcover(kpart) ! --- offset for pbcs
-     end subroutine do_comms
+
+    k_off=a_b_c%ahalo%lab_hcover(kpart) ! --- offset for pbcs
+  end subroutine do_comms
 
   !!****f* multiply_module/prefetch *
   !!