本文介绍了C OMP omp_get_wtime()返回时间0.00的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我已经使用过omp_get_wtime(),但是当我想打印时间时,我总是得到0.00,这是哪里出了问题?
I have used a omp_get_wtime() but when i want to print the time i always get 0.00, where is the problem ?
#define SIZE 500
#define nthreads 10
(...)
void sumTab(int mX[][SIZE], int mY[][SIZE], int mZ[][SIZE]) {
int i,k;
double start = omp_get_wtime();
#pragma omp parallel for schedule(dynamic,3) private(i) num_threads(nthreads)
for(i=0 ; i<SIZE ; i++)
{
for(k=0 ; k<SIZE ; k++)
{
mZ[i][k]=mX[i][k]+mY[i][k];
printf("Thread no %d \t [%d] [%d] result: %d\n", omp_get_thread_num(),i,k, mZ[i][k]);
}
}
printf("Time: \t %f \n", omp_get_wtime()-start);
}
推荐答案
确保在文件的标题中包含omp.h库.
Make sure you include the omp.h library in the header of the file.
#include <omp.h>
double start_time = omp_get_wtime();
#pragma omp parallel [...]
// code
double time = omp_get_wtime() - start_time;
此库将在编译时删除此警告:
This library will remove this warning in compilation:
warning: implicit declaration of function ‘omp_get_wtime’ [-Wimplicit-function-declaration]
时间会正确显示.
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