ChoChoX/C-exp-collection
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ChoChoX
2026-06-09 06:43:13 +02:00
parent 43902c20e4
commit 2f42b036a9
33 changed files with 2077 additions and 40 deletions
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39
exp1/task64.c
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@@ -1,6 +1,7 @@
/*任务4(必做）：编译、测试和运行示例程序psum64.c
/*
任务4(必做）：编译、测试和运行示例程序psum64.c
1）测量线程数为1、2、4、8、16时程序的执行时间，计算加速比和效率，并做出解释。
2）改写该程序psum64.c,保存为task64.c，实现计算02+12+… +(n-1)2功能。
2）改写该程序psum64.c,保存为task64.c，实现计算0²+1²+…+(n-1)²功能。
*/
#include <stdio.h>
@@ -19,50 +20,50 @@ double get_time()
return tv.tv_sec + tv.tv_usec / 1000000.0;
}
unsigned long long psum64[MAXTHREADS];
unsigned long long nelems_per_thread;
int main(int argc, char **argv)
{
unsigned long long i,nelems,log_nelems,nthreads,result = 0;
unsigned long long i, nelems, log_nelems, nthreads, result = 0;
pthread_t tid[MAXTHREADS];
int myid[MAXTHREADS];
if(argc != 3)
if (argc != 3)
{
printf("Usage: %s <nthreads> <log_nelems>\n",argv[0]);
printf("Usage: %s <nthreads> <log_nelems>\n", argv[0]);
exit(0);
}
nthreads = atoi(argv[1]);
log_nelems = atoi(argv[2]);
nelems = (1LL << log_nelems);
nelems_per_thread = nelems / nthreads;
double t_start = get_time();
for ( i = 0; i < nthreads; i++)
for (i = 0; i < nthreads; i++)
{
myid[i] = i;
pthread_create(&tid[i],NULL,sum,&myid[i]);
pthread_create(&tid[i], NULL, sum, &myid[i]);
}
for ( i = 0; i < nthreads; i++)
for (i = 0; i < nthreads; i++)
{
pthread_join(tid[i],NULL);
pthread_join(tid[i], NULL);
}
for ( i = 0; i < nthreads; i++)
for (i = 0; i < nthreads; i++)
{
result += psum64[i];
}
if (result == (nelems*(nelems-1)*(2*nelems-1))/6)
/* 验证公式: 0²+1²+...+(n-1)² = (n-1)*n*(2n-1)/6 */
if (result == (nelems * (nelems - 1) * (2 * nelems - 1)) / 6)
{
printf("Correct result: %llu\n",result);
printf("Correct result: %llu\n", result);
}
else
{
printf("Wrong result: %llu\n",result);
printf("Wrong result: %llu\n", result);
}
double t_end = get_time();
printf("Time taken: %f seconds\n", t_end - t_start);
@@ -70,14 +71,12 @@ int main(int argc, char **argv)
exit(0);
}
void *sum(void *vargp)
{
int myid = *((int *)vargp);
unsigned long long begin = myid * nelems_per_thread;
unsigned long long end = begin + nelems_per_thread;
unsigned long long i,lsum=0;
unsigned long long i, lsum = 0;
for (i = begin; i < end; i++)
{
@@ -86,4 +85,4 @@ void *sum(void *vargp)
psum64[myid] = lsum;
return NULL;
}
}