MPI二维笛卡尔坐标划分【1】

本文简单演示，如何对现有进程进行二维划分，如何获得进程的X和Y坐标。

只有一段程序：

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

int main(int argc, char **argv)
{

  int rank,size;

  int rankX, rankY;
  int ndims = 2;
  int dims[2] = {2, 2};
  int periods[2] = {0, 0};
  int reorder = 0;

  int remainX[2] = {1, 0};
  int remainY[2] = {0, 1}; 

  MPI_Comm comm2d;
  MPI_Comm commX, commY;

  MPI_Init(&argc, &argv);

  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  MPI_Comm_size(MPI_COMM_WORLD, &size);

  MPI_Cart_create(MPI_COMM_WORLD, ndims, dims, periods, reorder, &comm2d);
  MPI_Cart_sub(comm2d, remainX, &commX);
  MPI_Cart_sub(comm2d, remainY, &commY);

  MPI_Comm_rank(commX, &rankX);
  MPI_Comm_rank(commY, &rankY);

  printf("rank = %d;   X = %d;  Y = %d\n", rank, rankX, rankY);

  MPI_Finalize();

  return 0;
}

将上面这段程序拷贝到test.c文件中。

Makefile内容如下

TARGET = test.exe

all : test.c
  mpicc -g -O0 $^ -o $(TARGET)

run : $(TARGET)
  mpiexec -n 4 ./$(TARGET)

clean :
  rm *.exe -rf

实验结果：

mpiexec -n 4 ./test.exe
rank = 0;   X = 0;  Y = 0
rank = 2;   X = 1;  Y = 0
rank = 3;   X = 1;  Y = 1
rank = 1;   X = 0;  Y = 1