如何在C中使用nanosleep()？什么是`tim.tv_sec`和`tim.tv_nsec`？

Question

有什么用的tim.tv_sec,并tim.tv_nsec在下面？

如何在500000微秒内执行睡眠？

#include <stdio.h>
#include <time.h>

int main()
{
   struct timespec tim, tim2;
   tim.tv_sec = 1;
   tim.tv_nsec = 500;

   if(nanosleep(&tim , &tim2) < 0 )   
   {
      printf("Nano sleep system call failed \n");
      return -1;
   }

   printf("Nano sleep successfull \n");

   return 0;
}

Answer 1

半秒是500,000,000纳秒,因此您的代码应为:

tim.tv_sec  = 0;
tim.tv_nsec = 500000000L;

事实上,你的代码正在睡眠1.0000005s(1s + 500ns).

Answer 2

tv_nsec是以纳秒为单位的睡眠时间.500000us = 500000000ns,所以你想要:

nanosleep((const struct timespec[]){{0, 500000000L}}, NULL);

Answer 3

500000微秒是500000000纳秒.您只需等待500 ns =0.5μs.

Answer 4

我通常使用一些#define和常量来简化计算:

#define NANO_SECOND_MULTIPLIER  1000000  // 1 millisecond = 1,000,000 Nanoseconds
const long INTERVAL_MS = 500 * NANO_SECOND_MULTIPLIER;

因此我的代码看起来像这样:

timespec sleepValue = {0};

sleepValue.tv_nsec = INTERVAL_MS;
nanosleep(&sleepValue, NULL);

Answer 5

这对我有用。

#include <stdio.h>
#include <time.h>   /* Needed for struct timespec */


int nsleep(long miliseconds)
{
   struct timespec req, rem;

   if(miliseconds > 999)
   {   
        req.tv_sec = (int)(miliseconds / 1000);                            /* Must be Non-Negative */
        req.tv_nsec = (miliseconds - ((long)req.tv_sec * 1000)) * 1000000; /* Must be in range of 0 to 999999999 */
   }   
   else
   {   
        req.tv_sec = 0;                         /* Must be Non-Negative */
        req.tv_nsec = miliseconds * 1000000;    /* Must be in range of 0 to 999999999 */
   }   

   return nanosleep(&req , &rem);
}

int main()
{
   int ret = nsleep(2500);
   printf("sleep result %d\n",ret);
   return 0;
}