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clover.f90
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!Crown Copyright 2012 AWE.
!
! This file is part of CloverLeaf.
!
! CloverLeaf is free software: you can redistribute it and/or modify it under
! the terms of the GNU General Public License as published by the
! Free Software Foundation, either version 3 of the License, or (at your option)
! any later version.
!
! CloverLeaf is distributed in the hope that it will be useful, but
! WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
! FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
! details.
!
! You should have received a copy of the GNU General Public License along with
! CloverLeaf. If not, see http://www.gnu.org/licenses/.
!> @brief Communication Utilities
!> @author Wayne Gaudin
!> @details Contains all utilities required to run CloverLeaf in a distributed
!> environment, including initialisation, mesh decompostion, reductions and
!> halo exchange using explicit buffers.
!>
!> Note the halo exchange is currently coded as simply as possible and no
!> optimisations have been implemented, such as post receives before sends or packing
!> buffers with multiple data fields. This is intentional so the effect of these
!> optimisations can be measured on large systems, as and when they are added.
!>
!> Even without these modifications CloverLeaf weak scales well on moderately sized
!> systems of the order of 10K cores.
MODULE clover_module
USE data_module
USE definitions_module
IMPLICIT NONE
CONTAINS
SUBROUTINE clover_barrier
INTEGER :: err
END SUBROUTINE clover_barrier
SUBROUTINE clover_abort
INTEGER :: ierr,err
END SUBROUTINE clover_abort
SUBROUTINE clover_finalize
INTEGER :: err
CLOSE(g_out)
CALL FLUSH(0)
CALL FLUSH(6)
CALL FLUSH(g_out)
END SUBROUTINE clover_finalize
SUBROUTINE clover_init_comms
IMPLICIT NONE
INTEGER :: err,rank,size
rank=0
size=1
parallel%parallel=.TRUE.
parallel%task=rank
IF(rank.EQ.0) THEN
parallel%boss=.TRUE.
ENDIF
parallel%boss_task=0
parallel%max_task=size
END SUBROUTINE clover_init_comms
SUBROUTINE clover_get_num_chunks(count)
IMPLICIT NONE
INTEGER :: count
! Should be changed so there can be more than one chunk per mpi task
count=parallel%max_task
END SUBROUTINE clover_get_num_chunks
SUBROUTINE clover_decompose(x_cells,y_cells,left,right,bottom,top)
! This decomposes the mesh into a number of chunks.
! The number of chunks may be a multiple of the number of mpi tasks
! Doesn't always return the best split if there are few factors
! All factors need to be stored and the best picked. But its ok for now
IMPLICIT NONE
INTEGER :: x_cells,y_cells,left(:),right(:),top(:),bottom(:)
INTEGER :: c,delta_x,delta_y
REAL(KIND=8) :: mesh_ratio,factor_x,factor_y
INTEGER :: chunk_x,chunk_y,mod_x,mod_y,split_found
INTEGER :: cx,cy,chunk,add_x,add_y,add_x_prev,add_y_prev
! 2D Decomposition of the mesh
mesh_ratio=real(x_cells)/real(y_cells)
chunk_x=number_of_chunks
chunk_y=1
split_found=0 ! Used to detect 1D decomposition
DO c=1,number_of_chunks
IF (MOD(number_of_chunks,c).EQ.0) THEN
factor_x=number_of_chunks/real(c)
factor_y=c
!Compare the factor ratio with the mesh ratio
IF(factor_x/factor_y.LE.mesh_ratio) THEN
chunk_y=c
chunk_x=number_of_chunks/c
split_found=1
EXIT
ENDIF
ENDIF
ENDDO
IF(split_found.EQ.0.OR.chunk_y.EQ.number_of_chunks) THEN ! Prime number or 1D decomp detected
IF(mesh_ratio.GE.1.0) THEN
chunk_x=number_of_chunks
chunk_y=1
ELSE
chunk_x=1
chunk_y=number_of_chunks
ENDIF
ENDIF
delta_x=x_cells/chunk_x
delta_y=y_cells/chunk_y
mod_x=MOD(x_cells,chunk_x)
mod_y=MOD(y_cells,chunk_y)
! Set up chunk mesh ranges and chunk connectivity
add_x_prev=0
add_y_prev=0
chunk=1
DO cy=1,chunk_y
DO cx=1,chunk_x
add_x=0
add_y=0
IF(cx.LE.mod_x)add_x=1
IF(cy.LE.mod_y)add_y=1
left(chunk)=(cx-1)*delta_x+1+add_x_prev
right(chunk)=left(chunk)+delta_x-1+add_x
bottom(chunk)=(cy-1)*delta_y+1+add_y_prev
top(chunk)=bottom(chunk)+delta_y-1+add_y
chunks(chunk)%chunk_neighbours(chunk_left)=chunk_x*(cy-1)+cx-1
chunks(chunk)%chunk_neighbours(chunk_right)=chunk_x*(cy-1)+cx+1
chunks(chunk)%chunk_neighbours(chunk_bottom)=chunk_x*(cy-2)+cx
chunks(chunk)%chunk_neighbours(chunk_top)=chunk_x*(cy)+cx
IF(cx.EQ.1)chunks(chunk)%chunk_neighbours(chunk_left)=external_face
IF(cx.EQ.chunk_x)chunks(chunk)%chunk_neighbours(chunk_right)=external_face
IF(cy.EQ.1)chunks(chunk)%chunk_neighbours(chunk_bottom)=external_face
IF(cy.EQ.chunk_y)chunks(chunk)%chunk_neighbours(chunk_top)=external_face
IF(cx.LE.mod_x)add_x_prev=add_x_prev+1
chunk=chunk+1
ENDDO
add_x_prev=0
IF(cy.LE.mod_y)add_y_prev=add_y_prev+1
ENDDO
IF(parallel%boss)THEN
WRITE(g_out,*)
WRITE(g_out,*)"Mesh ratio of ",mesh_ratio
WRITE(g_out,*)"Decomposing the mesh into ",chunk_x," by ",chunk_y," chunks"
WRITE(g_out,*)
ENDIF
END SUBROUTINE clover_decompose
SUBROUTINE clover_allocate_buffers(chunk)
IMPLICIT NONE
INTEGER :: chunk
! Unallocated buffers for external boundaries caused issues on some systems so they are now
! all allocated
IF(parallel%task.EQ.chunks(chunk)%task)THEN
!IF(chunks(chunk)%chunk_neighbours(chunk_left).NE.external_face) THEN
ALLOCATE(chunks(chunk)%left_snd_buffer(2*(chunks(chunk)%field%y_max+5)))
ALLOCATE(chunks(chunk)%left_rcv_buffer(2*(chunks(chunk)%field%y_max+5)))
!ENDIF
!IF(chunks(chunk)%chunk_neighbours(chunk_right).NE.external_face) THEN
ALLOCATE(chunks(chunk)%right_snd_buffer(2*(chunks(chunk)%field%y_max+5)))
ALLOCATE(chunks(chunk)%right_rcv_buffer(2*(chunks(chunk)%field%y_max+5)))
!ENDIF
!IF(chunks(chunk)%chunk_neighbours(chunk_bottom).NE.external_face) THEN
ALLOCATE(chunks(chunk)%bottom_snd_buffer(2*(chunks(chunk)%field%x_max+5)))
ALLOCATE(chunks(chunk)%bottom_rcv_buffer(2*(chunks(chunk)%field%x_max+5)))
!ENDIF
!IF(chunks(chunk)%chunk_neighbours(chunk_top).NE.external_face) THEN
ALLOCATE(chunks(chunk)%top_snd_buffer(2*(chunks(chunk)%field%x_max+5)))
ALLOCATE(chunks(chunk)%top_rcv_buffer(2*(chunks(chunk)%field%x_max+5)))
!ENDIF
ENDIF
END SUBROUTINE clover_allocate_buffers
SUBROUTINE clover_exchange(fields,depth)
IMPLICIT NONE
INTEGER :: fields(:),depth
! Assuming 1 patch per task, this will be changed
! Also, not packing all fields for each communication, doing one at a time
IF(fields(FIELD_DENSITY0).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%density0, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,CELL_DATA)
ENDIF
IF(fields(FIELD_DENSITY1).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%density1, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,CELL_DATA)
ENDIF
IF(fields(FIELD_ENERGY0).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%energy0, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,CELL_DATA)
ENDIF
IF(fields(FIELD_ENERGY1).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%energy1, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,CELL_DATA)
ENDIF
IF(fields(FIELD_PRESSURE).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%pressure, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,CELL_DATA)
ENDIF
IF(fields(FIELD_VISCOSITY).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%viscosity, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,CELL_DATA)
ENDIF
IF(fields(FIELD_SOUNDSPEED).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%soundspeed, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,CELL_DATA)
ENDIF
IF(fields(FIELD_XVEL0).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%xvel0, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,VERTEX_DATA)
ENDIF
IF(fields(FIELD_XVEL1).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%xvel1, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,VERTEX_DATA)
ENDIF
IF(fields(FIELD_YVEL0).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%yvel0, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,VERTEX_DATA)
ENDIF
IF(fields(FIELD_YVEL1).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%yvel1, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,VERTEX_DATA)
ENDIF
IF(fields(FIELD_VOL_FLUX_X).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%vol_flux_x, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,X_FACE_DATA)
ENDIF
IF(fields(FIELD_VOL_FLUX_Y).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%vol_flux_y, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,Y_FACE_DATA)
ENDIF
IF(fields(FIELD_MASS_FLUX_X).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%mass_flux_x, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,X_FACE_DATA)
ENDIF
IF(fields(FIELD_MASS_FLUX_Y).EQ.1) THEN
CALL clover_exchange_message(parallel%task+1,chunks(parallel%task+1)%field%mass_flux_y, &
chunks(parallel%task+1)%left_snd_buffer, &
chunks(parallel%task+1)%left_rcv_buffer, &
chunks(parallel%task+1)%right_snd_buffer, &
chunks(parallel%task+1)%right_rcv_buffer, &
chunks(parallel%task+1)%bottom_snd_buffer, &
chunks(parallel%task+1)%bottom_rcv_buffer, &
chunks(parallel%task+1)%top_snd_buffer, &
chunks(parallel%task+1)%top_rcv_buffer, &
depth,Y_FACE_DATA)
ENDIF
END SUBROUTINE clover_exchange
SUBROUTINE clover_exchange_message(chunk,field, &
left_snd_buffer, &
left_rcv_buffer, &
right_snd_buffer, &
right_rcv_buffer, &
bottom_snd_buffer, &
bottom_rcv_buffer, &
top_snd_buffer, &
top_rcv_buffer, &
depth,field_type)
USE pack_kernel_module
IMPLICIT NONE
REAL(KIND=8) :: field(-1:,-1:) ! This seems to work for any type of mesh data
REAL(KIND=8) :: left_snd_buffer(:),left_rcv_buffer(:),right_snd_buffer(:),right_rcv_buffer(:)
REAL(KIND=8) :: bottom_snd_buffer(:),bottom_rcv_buffer(:),top_snd_buffer(:),top_rcv_buffer(:)
INTEGER :: chunk,depth,field_type
INTEGER :: size,err,request(8),tag,message_count,x_inc,y_inc
INTEGER :: receiver,sender
! Field type will either be cell, vertex, x_face or y_face to get the message limits correct
! but this will do for now
! I am also sending buffers to chunks with the same task id for now.
! This can be improved in the future but at the moment there is just 1 chunk per task anyway
! The tag will be a function of the sending chunk and the face it is coming from
! like chunk 6 sending the left face
! No open mp in here either. May be beneficial will packing and unpacking in the future, though I am not sure.
! Change this so it will allow more than 1 chunk per task
request=0
message_count=0
! Pack and send
! These array modifications still need to be added on, plus the donor data location changes as in update_halo
IF(field_type.EQ.CELL_DATA) THEN
x_inc=0
y_inc=0
ENDIF
IF(field_type.EQ.VERTEX_DATA) THEN
x_inc=1
y_inc=1
ENDIF
IF(field_type.EQ.X_FACE_DATA) THEN
x_inc=1
y_inc=0
ENDIF
IF(field_type.EQ.Y_FACE_DATA) THEN
x_inc=0
y_inc=1
ENDIF
! Pack real data into buffers
IF(parallel%task.EQ.chunks(chunk)%task) THEN
size=(1+(chunks(chunk)%field%y_max+y_inc+depth)-(chunks(chunk)%field%y_min-depth))*depth
CALL pack_left_right_buffers(chunks(chunk)%field%x_min,chunks(chunk)%field%x_max, &
chunks(chunk)%field%y_min,chunks(chunk)%field%y_max, &
chunks(chunk)%chunk_neighbours(chunk_left), &
chunks(chunk)%chunk_neighbours(chunk_right), &
external_face, &
x_inc,y_inc,depth,size, &
field,left_snd_buffer,right_snd_buffer)
! Send/receive the data
IF(chunks(chunk)%chunk_neighbours(chunk_left).NE.external_face) THEN
tag=4*(chunk)+1 ! 4 because we have 4 faces, 1 because it is leaving the left face
receiver=chunks(chunks(chunk)%chunk_neighbours(chunk_left))%task
tag=4*(chunks(chunk)%chunk_neighbours(chunk_left))+2 ! 4 because we have 4 faces, 1 because it is coming from the right face of the left neighbour
sender=chunks(chunks(chunk)%chunk_neighbours(chunk_left))%task
message_count=message_count+2
ENDIF
IF(chunks(chunk)%chunk_neighbours(chunk_right).NE.external_face) THEN
tag=4*chunk+2 ! 4 because we have 4 faces, 2 because it is leaving the right face
receiver=chunks(chunks(chunk)%chunk_neighbours(chunk_right))%task
tag=4*(chunks(chunk)%chunk_neighbours(chunk_right))+1 ! 4 because we have 4 faces, 1 because it is coming from the left face of the right neighbour
sender=chunks(chunks(chunk)%chunk_neighbours(chunk_right))%task
message_count=message_count+2
ENDIF
ENDIF
! Wait for the messages
! Unpack buffers in halo cells
IF(parallel%task.EQ.chunks(chunk)%task) THEN
CALL unpack_left_right_buffers(chunks(chunk)%field%x_min,chunks(chunk)%field%x_max, &
chunks(chunk)%field%y_min,chunks(chunk)%field%y_max, &
chunks(chunk)%chunk_neighbours(chunk_left), &
chunks(chunk)%chunk_neighbours(chunk_right), &
external_face, &
x_inc,y_inc,depth,size, &
field,left_rcv_buffer,right_rcv_buffer)
ENDIF
request=0
message_count=0
! Pack real data into buffers
IF(parallel%task.EQ.chunks(chunk)%task) THEN
size=(1+(chunks(chunk)%field%x_max+x_inc+depth)-(chunks(chunk)%field%x_min-depth))*depth
CALL pack_top_bottom_buffers(chunks(chunk)%field%x_min,chunks(chunk)%field%x_max, &
chunks(chunk)%field%y_min,chunks(chunk)%field%y_max, &
chunks(chunk)%chunk_neighbours(chunk_bottom), &
chunks(chunk)%chunk_neighbours(chunk_top), &
external_face, &
x_inc,y_inc,depth,size, &
field,bottom_snd_buffer,top_snd_buffer)
! Send/receive the data
IF(chunks(chunk)%chunk_neighbours(chunk_bottom).NE.external_face) THEN
tag=4*(chunk)+3 ! 4 because we have 4 faces, 3 because it is leaving the bottom face
receiver=chunks(chunks(chunk)%chunk_neighbours(chunk_bottom))%task
tag=4*(chunks(chunk)%chunk_neighbours(chunk_bottom))+4 ! 4 because we have 4 faces, 1 because it is coming from the top face of the bottom neighbour
sender=chunks(chunks(chunk)%chunk_neighbours(chunk_bottom))%task
message_count=message_count+2
ENDIF
IF(chunks(chunk)%chunk_neighbours(chunk_top).NE.external_face) THEN
tag=4*(chunk)+4 ! 4 because we have 4 faces, 4 because it is leaving the top face
receiver=chunks(chunks(chunk)%chunk_neighbours(chunk_top))%task
tag=4*(chunks(chunk)%chunk_neighbours(chunk_top))+3 ! 4 because we have 4 faces, 4 because it is coming from the left face of the top neighbour
sender=chunks(chunks(chunk)%chunk_neighbours(chunk_top))%task
message_count=message_count+2
ENDIF
ENDIF
! Wait for the messages
! Unpack buffers in halo cells
IF(parallel%task.EQ.chunks(chunk)%task) THEN
CALL unpack_top_bottom_buffers(chunks(chunk)%field%x_min,chunks(chunk)%field%x_max, &
chunks(chunk)%field%y_min,chunks(chunk)%field%y_max, &
chunks(chunk)%chunk_neighbours(chunk_bottom), &
chunks(chunk)%chunk_neighbours(chunk_top), &
external_face, &
x_inc,y_inc,depth,size, &
field,bottom_rcv_buffer,top_rcv_buffer)
ENDIF
END SUBROUTINE clover_exchange_message
SUBROUTINE clover_sum(value)
! Only sums to the master
IMPLICIT NONE
REAL(KIND=8) :: value
REAL(KIND=8) :: total
INTEGER :: err
total=value
value=total
END SUBROUTINE clover_sum
SUBROUTINE clover_min(value)
IMPLICIT NONE
REAL(KIND=8) :: value
REAL(KIND=8) :: minimum
INTEGER :: err
minimum=value
value=minimum
END SUBROUTINE clover_min
SUBROUTINE clover_max(value)
IMPLICIT NONE
REAL(KIND=8) :: value
REAL(KIND=8) :: maximum
INTEGER :: err
maximum=value
value=maximum
END SUBROUTINE clover_max
SUBROUTINE clover_allgather(value,values)
IMPLICIT NONE
REAL(KIND=8) :: value
REAL(KIND=8) :: values(parallel%max_task)
INTEGER :: err
values(1)=value ! Just to ensure it will work in serial
END SUBROUTINE clover_allgather
SUBROUTINE clover_check_error(error)
IMPLICIT NONE
INTEGER :: error
INTEGER :: maximum
INTEGER :: err
maximum=error
error=maximum
END SUBROUTINE clover_check_error
END MODULE clover_module