并行程序设计入门

一、mpi

来自教材《并行程序设计导论》

mpi的helloworld程序

//test3_1.c
#include <stdio.h>
#include <string.h>
#include <mpi.h>

const int MAX_STRING = 100;
int main(void){
    char greeting[MAX_STRING];
    int comm_sz;
    int my_rank;
    int q;
    MPI_Init(NULL,NULL);
    MPI_Comm_size(MPI_COMM_WORLD,&comm_sz);
    MPI_Comm_rank(MPI_COMM_WORLD,&my_rank);

    if(my_rank!=0)
    {
        sprintf(greeting,"greetings from process %d of %d!",my_rank,comm_sz); //sprintf是给greeting赋值
        MPI_Send(greeting,strlen(greeting)+1,MPI_CHAR,0,0,MPI_COMM_WORLD);
    }
    else{
        printf("Greeting from process %d of %d!
",my_rank,comm_sz);
        for(q=1;q<comm_sz;q++)
        {
            MPI_Recv(greeting,MAX_STRING,MPI_CHAR,q,0,MPI_COMM_WORLD,MPI_STATUS_IGNORE);
            printf("%s
",greeting);
        }
    }
    MPI_Finalize();
    return 0;
}

可以通过mpicc -g -Wall -o test3_1 test3_1.c或者mpiexec -n 1 ./test3_1运行，获得可执行文件

然后

pbs脚本

#!/bin/bash
#PBS -N test3_1
#PBS -l nodes=1:ppn=8
#PBS -q AA000_queue
#PBS -j oe

cd $PBS_O_WORKDIR
procs=$(cat $PBS_NODEFILE | wc -l)
mpirun -np $procs -machinefile $PBS_NODEFILE ./test3_1 >& test.log

提交：qsub test3_1.pbs

查看：qstat

pbs脚本中
$PBS_NODEFILE，##这个环境变量表示由pbs 自动分配给作业的节点列表##

procs=$(cat $PBS_NODEFILE | wc -l) ##计算申请的 cpu 核数目，并后赋值给变量 NP）##

cd $PBS_O_WORKDIR ## (进入工作目录) ##

time mpirun -np &procs -machinefile $PBS_NODEFILE ./mpi 0.01 >& run1.log ##应该是传递两个参数，第一个为0.01，第二个为&procs，表示线程数##

查看test.log文件，可得到输出结果

Greeting from process 0 of 8!
greetings from process 1 of 8!
greetings from process 2 of 8!
greetings from process 3 of 8!
greetings from process 4 of 8!
greetings from process 5 of 8!
greetings from process 6 of 8!
greetings from process 7 of 8!

ppt中程序

错误代码

#include "mpi.h"
#include <stdio.h>
int foo(int i)
{
    return i;
}

int main(void)
{
    int i,tmp,group_size,my_rank,N=10,sum=0;
    MPI_Status status;
    MPI_Init(NULL,NULL);
    MPI_Comm_size(MPI_COMM_WORLD,&group_size);
    MPI_Comm_rank(MPI_COMM_WORLD,&my_rank);
    if(my_rank==0)
    {
        printf("group_size:%d
",group_size);
        for(i=1;i<group_size;i++)
        {
            printf("N=%d,i=%d
",N,i);
            MPI_Send(&N,1,MPI_INT,i,i,MPI_COMM_WORLD);
            printf("after send
");
        }
        printf("after send2 ,my_rank=%d
",my_rank);
        for(i=my_rank;i<N;i=i+group_size) {
            printf("my_rank=0,j=%d",i);
            sum=sum+foo(i);
        }
        printf("sum=sum+foo(i); %d",sum);
        for(i=1;i<group_size;i++){
            printf("for(i=1;i<group_size;i++)");
            MPI_Recv(&tmp,1,MPI_INT,i,i,MPI_COMM_WORLD,&status);
            sum=sum+tmp;
            printf("sum=sum+tmp; %d",sum);

        }
        printf("
 the result = %d",sum);
    }
    else
    {
        printf("MPI_Recv");
        MPI_Recv(&N,1,MPI_INT,0,i,MPI_COMM_WORLD,&status);
        //printf("else :i=%d,my_rank=%d",i,my_rank);
        printf("%d
",my_rank);
//        for(i=my_rank;i<N;i=i+group_size) {
//            sum=sum+foo(i);
//            printf("i in else is %d;sum in else %d
",i,sum);
//        }
        printf("before send in else");
        MPI_Send(&sum,1,MPI_INT,0,i,MPI_COMM_WORLD);
        printf("after send in else");
    }
    MPI_Finalize();
}