Lesson 12

Date: 4/21/2010
Computational clusters
Linux for Engineering and IT applications


MPI Collective Communications

  • Collective communication must involve all processes in the scope of a communicator. All processes are by default, members in the communicator MPI_COMM_WORLD.

    Some Frequently Used Collective Communication Routines

      MPI_Barrier (comm)
      MPI_Bcast (&buffer,count,datatype,root,comm)
      MPI_Scatter (&sendbuf,sendcnt,sendtype,&recvbuf,recvcnt,recvtype,root,comm)
      MPI_Gather (&sendbuf,sendcnt,sendtype,&recvbuf,recvcount,recvtype,root,comm)
      MPI_Allgather (&sendbuf,sendcount,sendtype,&recvbuf,recvcount,recvtype,comm)
      MPI_Reduce (&sendbuf,&recvbuf,count,datatype,op,root,comm)

    MPI Reduction Operation C Data Types Fortran Data Type
    MPI_MAX maximum integer, float integer, real, complex
    MPI_MIN minimum integer, float integer, real, complex
    MPI_SUM sum integer, float integer, real, complex
    MPI_PROD product integer, float integer, real, complex
    MPI_LAND logical AND integer logical
    MPI_BAND bit-wise AND integer, MPI_BYTE integer, MPI_BYTE
    MPI_LOR logical OR integer logical
    MPI_BOR bit-wise OR integer, MPI_BYTE integer, MPI_BYTE
    MPI_LXOR logical XOR integer logical
    MPI_BXOR bit-wise XOR integer, MPI_BYTE integer, MPI_BYTE
    MPI_MAXLOC max value and location float, double and long double real, complex,double precision
    MPI_MINLOC min value and location float, double and long double real, complex, double precision



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