On Wed, Jul 28, 2010 at 11:19:43AM -0400, Gus Correa wrote:
> Hugo Gagnon wrote:
>> Hi Gus,
>> Ompi_info --all lists its info regarding fortran right after C. In my
>> case:
>> Fort real size: 4
>> Fort real4 size: 4
>> Fort real8 size: 8
>> Fort real16 size: 16
>> Fort dbl prec size: 4
>> Does it make any sense to you?
>
> Hi Hugo
>
> No, dbl prec size 4 sounds weird, should be 8, I suppose,
> same as real8, right?
>
> It doesn't make sense, but that's what I have (now that you told me
> that "dbl" , not "double", is the string to search for):
>
> $ Fort dbl prec size: 4
> Fort dbl cplx size: 4
> Fort dbl prec align: 4
> Fort dbl cplx align: 4
>
> Is this a bug in OpenMPI perhaps?
>
> I didn't come across to this problem, most likely because
> the codes here don't use "double precision" but real*8 or similar.
>
> Also make sure you are picking the right ompi_info, mpif90/f77, mpiexec.
> Often times old versions and tangled PATH make things very confusing.
This is indeed worrisome as I confirm the findings on our clusters both
with ompi 1.3.3 and 1.4.1:
ompi_info --all | grep -i fort
...
Fort real size: 4
Fort real4 size: 4
Fort real8 size: 8
Fort real16 size: -1
Fort dbl prec size: 4
Fort cplx size: 4
Fort dbl cplx size: 4
Fort cplx8 size: 8
Fort cplx16 size: 16
Fort cplx32 size: -1
Fort integer align: 4
Fort integer1 align: 1
Fort integer2 align: 2
Fort integer4 align: 4
Fort integer8 align: 8
Fort integer16 align: -1
Fort real align: 4
Fort real4 align: 4
Fort real8 align: 8
Fort real16 align: -1
Fort dbl prec align: 4
Fort cplx align: 4
Fort dbl cplx align: 4
Fort cplx8 align: 4
Fort cplx16 align: 8
...
And this is the configure output:
checking if Fortran 77 compiler supports REAL*8... yes
checking size of Fortran 77 REAL*8... 8
checking for C type corresponding to REAL*8... double
checking alignment of Fortran REAL*8... 1
...
checking if Fortran 77 compiler supports DOUBLE PRECISION... yes
checking size of Fortran 77 DOUBLE PRECISION... 8
checking for C type corresponding to DOUBLE PRECISION... double
checking alignment of Fortran DOUBLE PRECISION... 1
But the following code actually appears to give the correct results:
program types
use mpi
implicit none
integer :: mpierr, size
call MPI_Init(mpierr)
call MPI_Type_size(MPI_DOUBLE_PRECISION, size, mpierr)
print*, 'double precision size: ', size
call MPI_Finalize(mpierr)
end
mpif90 -g types.f90
mpiexec -n 1 ./a.out
double precision size: 8
Thus is this a bug in ompi_info only?
Cheers,
Martin
--
Martin Siegert
Head, Research Computing
WestGrid/ComputeCanada Site Lead
IT Services phone: 778 782-4691
Simon Fraser University fax: 778 782-4242
Burnaby, British Columbia email: siegert_at_[hidden]
Canada V5A 1S6
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