采用MPI_Send 和MPI_Recv 编写代码来实现包括MPI_Bcast、MPI_Alltoall、MPI_Gather、MPI_Scatter 等MPI 群集通信函数的功能

本文引自百度文库

一、实验内容

1、采用MPI_Send 和MPI_Recv 编写代码来实现包括MPI_Bcast、MPI_Alltoall、MPI_Gather、MPI_Scatter 等MPI 群集通信函数的功能。

2、给出抽象的并行算法描述、程序源代码及运行时性能加速图表。

二、抽象并行算法描述

ⅰ、MPI_Bcast算法描述：

输入：并行处理器个数ProcessNumber

输出：所有进程收到来自Root进程的消息

Procedure MPI_Bcast_a

Begin

对所有处理器同时执行如下的算法：

（1）if 进程为Root进程

（1.1）将message写入消息缓冲

（1.2）for index=0 to size-1 do

向index发送相同的message消息

end for

（2）进程不是Root进程

（2.1）接收消息

End

2、MPI_Alltoall算法描述：

输入：并行处理器个数ProcessNumber

输出：所有进程收到来自其他进程不同的消息

Procedure MPI_Alltoall_a

Begin

对所有处理器同时执行如下的算法：

（1）将message写入消息缓冲

（2）for index=0 to size-1 do

分别向index发送不同的message消息

end for

（3）for source=0 to size-1 do

接收来自source的message消息

end for

End

3、MPI_Gather算法描述：

输入：并行处理器个数ProcessNumber

输出： Root进程从通信域Comm的所有进程接收消息

Procedure MPI_Gather_a

Begin

对所有处理器同时执行如下的算法：

（1）if 进程为Root进程

（1.1）for source=0 to size-1 do

接收来自source的message消息

end for

（2）向Root进程发送自己的消息

End

4、MPI_Scatter算法描述：

输入：并行处理器个数ProcessNumber

输出：向所有进程发送不同的消息

Procedure MPI_Scatter_a

Begin

对所有处理器同时执行如下的算法：

（1）if 进程为Root进程

（1.1）将message写入消息缓冲

（1.2）for index=0 to size-1 do

向index发送不同的message消息

end for

（2）进程不是Root进程

（2.1）接收消息

End

三、程序源代码

#include "mpi.h" /*MPI head file*/

#include <stdio.h>

#include <string.h>

#define ProNum 4

void MPI_Bcast_a(int rank,int size,int tag){ //

int index;

char message[100];

MPI_Status status;

if (rank==0){

strcpy(message,"Hello,the message is from process root!\n ");

for(index=0;index<size;index++){

MPI_Send(message,strlen(message), MPI_CHAR, index, tag, MPI_COMM_WORLD); /*sending data to node#1*/

}

printf("There are %d processes in the group.\n",size);

}

else{

MPI_Recv(message,100, MPI_CHAR, 0, tag, MPI_COMM_WORLD, &status);

printf("Process %d received %s\n",rank,message);

}

}

void MPI_Alltoall_a(int rank,int size,int tag){ //

int index,source;

char message[100];

char buffers[ProNum][100];//if buffers *[100],there will be errors.

char buffer[10];

MPI_Status status;

strcpy(message,"Hello,the message is from process ");

//message="Hello,the message is from process ";

snprintf(buffer,10,"%d",rank);

strcat(message,buffer);

for(index=0;index<size;index++){

MPI_Send(message,strlen(message), MPI_CHAR, index, tag, MPI_COMM_WORLD); /*sending data to node#1*/

}

printf("There are %d processes in the group.\n",size);

for(source=0;source<size;source++){

MPI_Recv(buffers[source],100, MPI_CHAR,source, tag, MPI_COMM_WORLD, &status);

printf("Process %d received %s\n",rank,buffers[source]);

}

}

void MPI_Gather_a(int rank,int size,int tag){ //

int index,source;

char message[100];

char buffers[ProNum][100];//

char buffer[10];

MPI_Status status;

strcpy(message,"Hello,the message is from process ");

//message="Hello,the message is from process ";

snprintf(buffer,10,"%d",rank);

strcat(message,buffer);

MPI_Send(message,strlen(message), MPI_CHAR, 0, tag, MPI_COMM_WORLD); /*sending data to node#1*/

printf("There are %d processes in the group.\n",size);

if(rank==0){

for(source=0;source<size;source++){

MPI_Recv(buffers[source],100, MPI_CHAR,source, tag, MPI_COMM_WORLD, &status);

printf("Process %d received %s\n",rank,buffers[source]);

}

}

}

void MPI_Scatter_a(int rank,int size,int tag){ //

int index,source;

char message[100];

//char buffers[ProNum][100];//if buffers *[100],there will be errors.

char buffer[10];

MPI_Status status;

strcpy(message,"Hello,the message is to process ");

//message="Hello,the message is from process ";

if(rank==0){

for(index=0;index<size;index++){

snprintf(buffer,10,"%d",index);

strcat(message,buffer);

MPI_Send(message,strlen(message), MPI_CHAR, index, tag, MPI_COMM_WORLD); /*sending data to node#1*/

}

}

printf("There are %d processes in the group.\n",size);

MPI_Recv(message,100, MPI_CHAR,0, tag, MPI_COMM_WORLD, &status);

printf("Process %d received %s\n",rank,message);

}

int main( int argc, char** argv )

{

int rank, size,index, tag=1;

int senddata,recvdata;

MPI_Status status;

MPI_Init(&argc, &argv); /*initializing */

MPI_Comm_rank(MPI_COMM_WORLD, &rank); /*Process#*/

MPI_Comm_size(MPI_COMM_WORLD, &size); /*Total processes#*/

MPI_Bcast_a(rank,size,tag);

MPI_Alltoall_a(rank,size,tag);

MPI_Gather_a(rank,size,tag);

MPI_Scatter_a(rank,size,tag);

MPI_Finalize(); /*quit from MPI world*/

return (0);

}