HelloWord

• 安装 MPI 运行环境
• HelloWorld
• 编译
• 运行

安装 MPI 运行环境

Installing MPICH2 on a Single Machine

去 MPICH2 官网下载源码包，然后安装

tar -xzf mpich-3.2.tar.gz
cd mpich-3.2
./configure --disable-fortran CC=gcc CXX=g++
make
sudo mark install

安装了 Intel 编译器的可以使用 mpiicc 和 mpiicpc

HelloWorld

#include <mpi.h>
#include <stdio.h>

int main(int argc, char** argv) {
    // Initialize the MPI environment
    MPI_Init(NULL, NULL);

    // Get the number of processes
    int world_size;
    MPI_Comm_size(MPI_COMM_WORLD, &world_size);

    // Get the rank of the process
    int world_rank;
    MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);

    // Get the name of the processor
    char processor_name[MPI_MAX_PROCESSOR_NAME];
    int name_len;
    MPI_Get_processor_name(processor_name, &name_len);

    // Print off a hello world message
    printf("Hello world from processor %s, rank %d"
           " out of %d processors\n",
           processor_name, world_rank, world_size);

    // Finalize the MPI environment.
    MPI_Finalize();
}

编译

mpicc -o helloworld helloworld.c

运行

mpiexec ./helloworld
// 或者
mpirun ./helloworld

mpirun 等同于 mpiexec

mpirun 命令

 mpirun -n <# of processes> -ppn <# of processes per node> -f <hostfile> ./myprog

• -n - sets the number of MPI processes to launch; if the option is not specified, the process manager pulls the host list from a job scheduler, or uses the number of cores on the machine.
• -ppn - sets the number of processes to launch on each node; if the option is not specified, processes are assigned to the physical cores on the first node; if the number of cores is exceeded, the next node is used.
• -f - specifies the path to the host file listing the cluster nodes; alternatively, you can use the -hosts option to specify a comma-separated list of nodes; if hosts are not specified, the local node is used.

如果需要在多个节点上运行运行，可以参考 无需超级用户mpi多机执行