Question

我想要一个'＃34; hello world＆＃34;使用OpenMP和MPI工作的程序。我从这里的例子开始

http://www.slac.stanford.edu/comp/unix/farm/mpi_and_openmp.html

但我无法重现输出。这是我正在使用的确切来源：

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

int main(int argc, char *argv[]) {
  int numprocs, rank, namelen;
  char processor_name[MPI_MAX_PROCESSOR_NAME];
  int iam = 0, np = 1;

  MPI_Init(&argc, &argv);
  MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  MPI_Get_processor_name(processor_name, &namelen);

  //omp_set_num_threads(4);

#pragma omp parallel default(shared) private(iam, np)
  {
    np = omp_get_num_threads();
    iam = omp_get_thread_num();
    printf("Hello from thread %d out of %d from process %d out of %d on %s\n",
           iam, np, rank, numprocs, processor_name);
  }

  MPI_Finalize();
}

我正在使用运行Ubuntu 12.10的双处理器Xeon工作站（2x6核心）。我可以毫无困难地使用MPI或OpenMP（但不是两者）来运行。

我使用命令

编译了上面的源代码

mpicc -fopenmp hello.c -o hello

然后使用

运行

export OMP_NUM_THREADS=4
mpirun ./hello -np 2 -x OMP_NUM_THREADS

以下是我得到的输出：

Hello from thread 0 out of 4 from process 0 out of 1 on SteinbergT5600Linux
Hello from thread 2 out of 4 from process 0 out of 1 on SteinbergT5600Linux
Hello from thread 1 out of 4 from process 0 out of 1 on SteinbergT5600Linux
Hello from thread 3 out of 4 from process 0 out of 1 on SteinbergT5600Linux

根据这个例子，我应该得到这样的东西：

Hello from thread 0 out of 4 from process 0 out of 2 on SteinbergT5600Linux
Hello from thread 2 out of 4 from process 0 out of 2 on SteinbergT5600Linux
Hello from thread 1 out of 4 from process 0 out of 2 on SteinbergT5600Linux
Hello from thread 3 out of 4 from process 0 out of 2 on SteinbergT5600Linux
Hello from thread 0 out of 4 from process 1 out of 2 on SteinbergT5600Linux
Hello from thread 2 out of 4 from process 1 out of 2 on SteinbergT5600Linux
Hello from thread 1 out of 4 from process 1 out of 2 on SteinbergT5600Linux
Hello from thread 3 out of 4 from process 1 out of 2 on SteinbergT5600Linux

任何人都可以给我一个关于我做错的提示吗？据我所知，我正在复制上面链接中的示例。

Answer 1

您将程序名称指定为mpirun的第一个参数，因此忽略其余参数（值得注意：-np 2）。因此，对于-np，您获得了系统范围内的默认值。

变化：

mpirun ./hello -np 2 -x OMP_NUM_THREADS

分为：

mpirun -np 2 -x OMP_NUM_THREADS ./hello

旁注：我在我的机器上对此进行了测试。此处-np的默认值为3。在您的计算机上，默认值为1

＆＃34;你好世界＆＃34;使用OpenMP和MPI混合的C程序

1 个答案: