Diego, Setting the color to MPI_COMM_NULL is not good, as it results in some random value (and not the MPI_UNDEFINED that do not generate a communicator). Change the color to MPI_UNDEFINED and your application should work just fine (in the sense that all processes not in the master communicator will have the master_comm variable set to MPI_COMM_NULL).
George. On Wed, Aug 2, 2017 at 10:15 AM, Diego Avesani <diego.aves...@gmail.com> wrote: > Dear Jeff, Dear all, > > thanks, I will try immediately. > > thanks again > > > > Diego > > > On 2 August 2017 at 14:01, Jeff Squyres (jsquyres) <jsquy...@cisco.com> > wrote: > >> Just like in your original code snippet, you can >> >> If (master_comm .ne. Mpi_comm_null) then >> ... >> >> Sent from my phone. No type good. >> >> On Aug 2, 2017, at 7:17 AM, Diego Avesani <diego.aves...@gmail.com> >> wrote: >> >> Dear all, Dear Jeff, >> >> I am very sorry, but I do not know how to do this kind of comparison. >> >> this is my peace of code: >> >> CALL MPI_GROUP_INCL(GROUP_WORLD, nPSObranch, MRANKS, MASTER_GROUP,ierr) >> CALL MPI_COMM_CREATE_GROUP(MPI_COMM_WORLD,MASTER_GROUP,0,MASTER_ >> COMM,iErr) >> ! >> IF(MPI_COMM_NULL .NE. MASTER_COMM)THEN >> CALL MPI_COMM_RANK(MASTER_COMM, MPImaster%rank,MPIlocal%iErr) >> CALL MPI_COMM_SIZE(MASTER_COMM, MPImaster%nCPU,MPIlocal%iErr) >> ELSE >> MPImaster%rank = MPI_PROC_NULL >> ENDIF >> >> and then >> >> IF(MPImaster%rank.GE.0)THEN >> CALL MPI_SCATTER(PP, 10, MPI_DOUBLE, PPL, 10,MPI_DOUBLE, 0, >> MASTER_COMM, iErr) >> ENDIF >> >> What I should compare? >> >> Thanks again >> >> Diego >> >> >> On 1 August 2017 at 16:18, Jeff Squyres (jsquyres) <jsquy...@cisco.com> >> wrote: >> >>> On Aug 1, 2017, at 5:56 AM, Diego Avesani <diego.aves...@gmail.com> >>> wrote: >>> > >>> > If I do this: >>> > >>> > CALL MPI_SCATTER(PP, npart, MPI_DOUBLE, PPL, 10,MPI_DOUBLE, 0, >>> MASTER_COMM, iErr) >>> > >>> > I get an error. This because some CPU does not belong to MATER_COMM. >>> The alternative should be: >>> > >>> > IF(rank.LT.0)THEN >>> > CALL MPI_SCATTER(PP, npart, MPI_DOUBLE, PPL, 10,MPI_DOUBLE, 0, >>> MASTER_COMM, iErr) >>> > ENDIF >>> >>> MPI_PROC_NULL is a sentinel value; I don't think you can make any >>> assumptions about its value (i.e., that it's negative). In practice, it >>> probably always is, but if you want to check the rank, you should compare >>> it to MPI_PROC_NULL. >>> >>> That being said, comparing MASTER_COMM to MPI_COMM_NULL is no more >>> expensive than comparing an integer. So that might be a bit more expressive >>> to read / easier to maintain over time, and it won't cost you any >>> performance. >>> >>> -- >>> Jeff Squyres >>> jsquy...@cisco.com >>> >>> _______________________________________________ >>> users mailing list >>> users@lists.open-mpi.org >>> https://lists.open-mpi.org/mailman/listinfo/users >>> >> >> _______________________________________________ >> users mailing list >> users@lists.open-mpi.org >> https://lists.open-mpi.org/mailman/listinfo/users >> >> >> _______________________________________________ >> users mailing list >> users@lists.open-mpi.org >> https://lists.open-mpi.org/mailman/listinfo/users >> > > > _______________________________________________ > users mailing list > users@lists.open-mpi.org > https://lists.open-mpi.org/mailman/listinfo/users >
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