使用pthreads的矩阵乘法 [英] Matrix multiplication using pthreads

问题描述

我想使用的pthreads和创造的每一行，而不是每个元素的计算每一个线程做矩阵乘法。假设有两个矩阵
A [M] [K]，B [K] [N]。我在哪里去了？

  int类型的[M] [K];
INT B〔K] [N];
INT C [] [];void *的亚军（无效*参数）;
结构v
{
INT I;
 诠释J;
};工业贸易署的pthread_t [M]。对于（i = 0; I＆LT;米;我++）//它应该创建中号线
{
    结构V *数据=（结构V *）malloc的（的sizeof（结构V））;
    数据 - ＆GT; I = I;
    数据 - ＆GT;当J = J;
    在pthread_create（安培; TID [计数]，＆安培; attr指示，亚军，数据）;
    在pthread_join（TID [计数]，NULL）;
    算上++;
}亚军（无效*参数）//
{
    结构V *测试;
    INT T = 0;
    测试=（结构V *）参数;    对于（t = 0; T＆所述; k;吨++）//欲计算它为一排，而不是一个元素的
    {
        C [测试 - ＆GT; I] [测试 - ＆GT; J] = C [测试 - ＆GT; I] [测试 - ＆GT; J] + A [测试 - ＆GT; I] [T] * B [T] [测试 - ＆GT; J]。
    }
    了pthread_exit（0）;
}
 

解决方案

首先，摆脱数据 - > j的。如果你计算整个行的行索引你的线程需要的唯一的事。现在你的亚军（..）计算一个元素。你必须通过一个遍历所有行元素计算其中之一。
其次，不要加入被创建之后的线程。这样，你只有一个线程同时运行。启动连接螺纹已创建的所有线程时。

I am trying to do matrix multiplication using pthreads and creating one thread for each computation of each row instead of each element. Suppose there are two matrices A[M][K],B[K][N] . Where am I going wrong ?

int A[M][K];
int B[K][N];
int C[][];

void *runner (void *param);


struct v
{
int i;
 int j;
};

pthread_t tid[M];

for (i = 0; i < M; i++) // It should create M threads 
{
    struct v *data = (struct v *) malloc (sizeof (struct v));
    data->i = i;
    data->j = j;
    pthread_create (&tid[count], &attr, runner, data);
    pthread_join (tid[count], NULL);
    count++;
}

runner (void *param) //
{
    struct v *test;
    int t = 0;
    test = (struct v *) param;

    for (t = 0; t < K; t++)  // I want to compute it for a row instead of an element 
    {
        C[test->i][test->j] = C[test->i][test->j] + A[test->i][t] * B[t][test->j];
    }
    pthread_exit (0);
}

解决方案

First, get rid of data->j. If you are computing entire rows the row index is the only thing your thread needs. Right now your runner(..) computes a single element. You have to iterate over all row elements computing them one by one. Second, do not join a thread right after it is created. This way you have only one thread running at a time. Start joining threads when all threads have been created.

这篇关于使用pthreads的矩阵乘法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！