Hi, MPI_Allreduce works for me with MPI_INTEGER8 for all OpenMPI versions up to 1.4.3. However, with OpenMPI 1.5.1 I get a failure at runtime:
[proton:23642] *** An error occurred in MPI_Allreduce: the reduction operation MPI_SUM is not defined on the MPI_INTEGER8 datatype [proton:23642] *** on communicator MPI_COMM_WORLD [proton:23642] *** MPI_ERR_OP: invalid reduce operation [proton:23642] *** MPI_ERRORS_ARE_FATAL (your MPI job will now abort) Funnily the reduction operation works for MPI_REAL8. Both 1.4.3 and 1.5.1 have been configured with Intel Fortran 12, but I get the failure only for 1.5.1 and only for integer8. % /opt/ifort12/openmpi-1.4/bin/ompi_info -all |grep integer8 Fort have integer8: yes Fort integer8 size: 8 Fort integer8 align: 1 % /opt/ifort12/openmpi-1.5/bin/ompi_info -all |grep integer8 Fort have integer8: yes Fort integer8 size: 8 Fort integer8 align: 1 Can anybody reproduce this? Cheers, Harald