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!
! Copyright (C) 2012, Northwestern University and Argonne National Laboratory
! See COPYRIGHT notice in top-level directory.
!
! $Id$
! This example is the Fortran 90 version of nonblocking_write.c
! It creates a netcdf file in CD-5 format and writes a number of
! 3D integer non-record variables.
! Usage: (for example)
! To compile:
! mpif90 -O2 nonblocking_write.f90 -o nonblocking_write -lpnetcdf
! To run:
! mpiexec -n num_processes ./nonblocking_write [filename] [len]
! where len decides the size of each local array, which is
! len x len x len. Each non-record variable is of size
! len*len*len * nprocs * sizeof(int)
! All variables are partitioned among all processes in a 3D
! block-block-block fashion.
!
subroutine check(err, message)
use mpi
use pnetcdf
implicit none
integer err
character(len=*) message
! It is a good idea to check returned value for possible error
if (err .NE. NF90_NOERR) then
write(6,*) trim(message), trim(nf90mpi_strerror(err))
call MPI_Abort(MPI_COMM_WORLD, -1, err)
end if
end subroutine check
program main
use mpi
use pnetcdf
implicit none
integer NDIMS, NUM_VARS
PARAMETER(NDIMS=3, NUM_VARS=10)
character(LEN=256) filename, cmd, str
integer i, cmode, err, ierr, get_args, info
integer rank, nprocs, len, bufsize, ncid
integer psizes(NDIMS), dimids(NDIMS), varids(NUM_VARS)
integer req(NUM_VARS), st(NUM_VARS)
integer(kind=MPI_OFFSET_KIND) gsizes(NDIMS)
integer(kind=MPI_OFFSET_KIND) starts(NDIMS), counts(NDIMS)
integer(kind=MPI_OFFSET_KIND) bbufsize
integer(kind=MPI_OFFSET_KIND) malloc_size, sum_size
logical verbose
! define an array of pointers
type intp
integer, dimension(:), pointer :: p
end type intp
type(intp) buf(NUM_VARS)
call MPI_Init(err)
call MPI_Comm_rank(MPI_COMM_WORLD, rank, err)
call MPI_Comm_size(MPI_COMM_WORLD, nprocs, err)
! take filename from command-line argument if there is any
if (rank .EQ. 0) then
verbose = .TRUE.
filename = "testfile.nc"
len = 10
ierr = get_args(3, cmd, filename, verbose, len)
endif
call MPI_Bcast(ierr, 1, MPI_INTEGER, 0, MPI_COMM_WORLD, err)
if (ierr .EQ. 0) goto 999
call MPI_Bcast(verbose, 1, MPI_LOGICAL, 0, MPI_COMM_WORLD, err)
call MPI_Bcast(filename, 256, MPI_CHARACTER, 0, MPI_COMM_WORLD, err)
call MPI_Bcast(len, 1, MPI_INTEGER, 0, MPI_COMM_WORLD, err)
do i=1,NDIMS
psizes(i) = 0
enddo
! create a block-block-block data partitioning
call MPI_Dims_create(nprocs, NDIMS, psizes, err);
starts(1) = mod(rank, psizes(1))
starts(2) = mod((rank / psizes(2)), psizes(2))
starts(3) = mod((rank / (psizes(1) * psizes(2))), psizes(3))
bufsize = 1
do i=1,NDIMS
gsizes(i) = len * psizes(i)
starts(i) = starts(i) * len + 1;
counts(i) = len;
bufsize = bufsize * len;
enddo
! allocate buffer and initialize with rank IDs
do i=1, NUM_VARS
allocate(buf(i)%p(bufsize))
buf(i)%p(:) = rank
enddo
! set an MPI-IO hint to disable file offset alignment for
! fixed-size variables
call MPI_Info_create(info, err)
call MPI_Info_set(info, "nc_var_align_size", "1", err)
! create file, truncate it if exists
cmode = IOR(NF90_CLOBBER, NF90_64BIT_DATA)
err = nf90mpi_create(MPI_COMM_WORLD, filename, cmode, &
info, ncid)
call check(err, 'In nf90mpi_create: ')
call MPI_Info_free(info, err)
! define dimensions
do i=1, NDIMS
write(str,'(I2)') i
err = nf90mpi_def_dim(ncid, "x"//trim(ADJUSTL(str)), &
gsizes(i), dimids(i))
call check(err, 'In nf90mpi_def_dim x'//trim(str))
enddo
!define variables
do i=1, NUM_VARS
write(str,'(I2)') i
err = nf90mpi_def_var(ncid, "var"//trim(ADJUSTL(str)), &
NF90_INT, dimids, varids(i))
call check(err, 'In nf90mpi_def_var var'//trim(str))
enddo
! do not forget to exit define mode
err = nf90mpi_enddef(ncid)
call check(err, 'In nf90mpi_enddef: ')
! write one variable at a time using iput
do i=1, NUM_VARS
write(str,'(I2)') i
err = nf90mpi_iput_var(ncid, varids(i), buf(i)%p, req(i), &
starts, counts)
call check(err, 'In nf90mpi_iput_var '//trim(str))
enddo
! wait for the nonblocking I/O to complete
err = nf90mpi_wait_all(ncid, NUM_VARS, req, st)
call check(err, 'In nf90mpi_wait_all')
! check the status of each nonblocking request
do i=1, NUM_VARS
write(str,'(I2)') i
call check(st(i), 'In nf90mpi_wait_all req '//trim(str))
enddo
! write one variable at a time using bput
! bbufsize must be max of data type converted before and after
bbufsize = bufsize * NUM_VARS * 4 ! 4 is size of integer
err = nf90mpi_buffer_attach(ncid, bbufsize)
call check(err, 'In nf90mpi_buffer_attach')
do i=1, NUM_VARS
write(str,'(I2)') i
err = nf90mpi_bput_var(ncid, varids(i), buf(i)%p, req(i), &
starts, counts)
call check(err, 'In nf90mpi_bput_var '//trim(str))
! can safely free up the buffer here
deallocate(buf(i)%p)
enddo
! wait for the nonblocking I/O to complete
err = nf90mpi_wait_all(ncid, NUM_VARS, req, st)
call check(err, 'In nf90mpi_wait_all')
! check the status of each nonblocking request
do i=1, NUM_VARS
write(str,'(I2)') i
call check(st(i), 'In nf90mpi_wait_all req '//trim(str))
enddo
! detach the temporary buffer
err = nf90mpi_buffer_detach(ncid)
call check(err, 'In nf90mpi_buffer_detach')
! close the file
err = nf90mpi_close(ncid);
call check(err, 'In nf90mpi_close')
! check if there is any PnetCDF internal malloc residue
998 format(A,I13,A)
err = nf90mpi_inq_malloc_size(malloc_size)
if (err == NF90_NOERR) then
call MPI_Reduce(malloc_size, sum_size, 1, MPI_INTEGER8, &
MPI_SUM, 0, MPI_COMM_WORLD, err)
if (rank .EQ. 0 .AND. sum_size .GT. 0_MPI_OFFSET_KIND) print 998, &
'heap memory allocated by PnetCDF internally has ', &
sum_size/1048576, ' MiB yet to be freed'
endif
999 call MPI_Finalize(err)
! call EXIT(0) ! EXIT() is a GNU extension
end program main
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