I assume you've confirmed that point to point communication works happily with quad prec on your machine? How about one-way reductions?
On Tue, 2008-10-28 at 08:47 +0000, Julien Devriendt wrote: > Thanks for your suggestions. > I tried them all (declaring my variables as REAL*16 or REAL(16)) to no > avail. I still get the wrong answer with my call to MPI_ALLREDUCE. > > > I think the KINDs are compiler dependent. For Sun Studio Fortran, REAL*16 > > and REAL(16) are the same thing. For Intel, maybe it's different. I don't > > know. Try running this program: > > > > double precision xDP > > real(16) x16 > > real*16 xSTAR16 > > write(6,*) kind(xDP), kind(x16), kind(xSTAR16), kind(1.0_16) > > end > > > > and checking if the output matches your expectations. > > > > Jeff Squyres wrote: > > > >> I dabble in Fortran but am not an expert -- is REAL(kind=16) the same as > >> REAL*16? MPI_REAL16 should be a 16 byte REAL; I'm not 100% sure that > >> REAL(kind=16) is the same thing...? > >> > >> On Oct 23, 2008, at 7:37 AM, Julien Devriendt wrote: > >> > >>> Hi, > >>> > >>> I'm trying to do an MPI_ALLREDUCE with quadruple precision real and > >>> MPI_SUM and open mpi does not give me the correct answer (vartemp > >>> is equal to vartored instead of 2*vartored). Switching to double > >>> precision > >>> real works fine. > >>> My version of openmpi is 1.2.7 and it has been compiled with ifort v10.1 > >>> and icc/icpc at installation > >>> > >>> Here's the simple f90 code which fails: > >>> > >>> program test_quad > >>> > >>> implicit none > >>> > >>> include "mpif.h" > >>> > >>> real(kind=16) :: vartored(8),vartemp(8) > >>> integer :: nn,nslaves,my_index > >>> integer :: mpierror > >>> > >>> call MPI_INIT(mpierror) > >>> call MPI_COMM_SIZE(MPI_COMM_WORLD,nslaves,mpierror) > >>> call MPI_COMM_RANK(MPI_COMM_WORLD,my_index,mpierror) > >>> > >>> nn = 8 > >>> vartored = 1.0_16 > >>> vartemp = 0.0_16 > >>> print*,"P1 ",my_index,vartored > >>> call MPI_ALLREDUCE > >>> (vartored,vartemp,nn,MPI_REAL16,MPI_SUM,MPI_COMM_WORLD,mpierror) > >>> print*,"P2 ",my_index,vartemp > >>> > >>> stop > >>> > >>> end program test_quad > >>> > >>> Any idea why this happens? > >> > > _______________________________________________ > > users mailing list > > us...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
