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Hi,Good day! I am attaching a Fortran code in that, I am trying parallel IO. It is writing approx 56 GB data. But, to call *nf90_def_var *takes a lot time approx 90 sec. Also, *nf90_unlimited* does not work when I replace NZ with *nf90_unlimited*. It probably fails during write operation it gives "HDF error". Please could you suggest me how can I improve performance in parallel I/O. I am attaching the file here.
Thanks a lot in advance Alok
use netcdf
use mpi
character (len = *), parameter :: FILE_NAME = "a_xy.nc"
integer, parameter :: NDIMS =3,NX=10000,NY=880,NZ=1600
real(4) A(NX,NY)
integer I,J
integer ncid, varid, dimids(NDIMS),chunksizes(NDIMS)
integer x_dimid, y_dimid,z_dimid
integer start(NDIMS),count(NDIMS)
integer rank,nprocs,J1,J2,ierr
double precision t1,t2,t3,t4
call MPI_Init(ierr)
call MPI_Comm_rank(MPI_COMM_WORLD, rank, ierr)
call MPI_Comm_size(MPI_COMM_WORLD, nprocs, ierr)
J1=rank*NZ/nprocs+1
J2=(rank+1)*NZ/nprocs
DO J=1,NY
DO I=1,NX
A(I,J)=rand()
ENDDO
ENDDO
T3=MPI_WTIME()
call check( nf90_create(FILE_NAME, NF90_NETCDF4, &
ncid, comm=MPI_COMM_WORLD, &
info = MPI_INFO_NULL) )
call check( nf90_def_dim(ncid, "y", NY, y_dimid) )
call check( nf90_def_dim(ncid, "x", NX, x_dimid) )
call check( nf90_def_dim(ncid, "z", NZ, z_dimid) )
dimids = (/x_dimid, y_dimid,z_dimid/)
T4=MPI_WTIME()
call check(nf90_def_var(ncid, "data", NF90_REAL4, dimids,varid))
call check( nf90_enddef(ncid) )
T1=MPI_WTIME()
DO J=J1,J2
start= (/1,1,J /)
count= (/NX,NY,1/)
call check( nf90_put_var(ncid, varid, A,start = start, &
count = count) )
ENDDO
call check( nf90_close(ncid) )
T2=MPI_WTIME()
print* ,'TIME',T2-T1,T1-T3,T1-T4,T1,rank
call mpi_finalize(ierr)
contains
subroutine check(status)
integer, intent ( in) :: status
if(status /= nf90_noerr) then
print *, trim(nf90_strerror(status))
stop 2
end if
end subroutine
end
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