Timeval 结构体的使用

Question

我需要计算运行某个函数所需要的时间，然后遇到下面的代码，记录并输出一段代码的执行时间，单位为纳秒

还有和有什么区别

struct timeval timer_spent & timeval timer_spent

/* Put this line at the top of the file: */
#include <sys/time.h>

/* Put this right before the code you want to time: */
struct timeval timer_start, timer_end;
gettimeofday(&timer_start, NULL);

/* Put this right after the code you want to time: */
gettimeofday(&timer_end, NULL);
double timer_spent = timer_end.tv_sec - timer_start.tv_sec + (timer_end.tv_usec - timer_start.tv_usec);
printf("Time spent: %.6f\n", timer_spent)/1000000.0;

但我需要以纳秒为单位的精确时间。我对 timeval 结构一无所知。

请大家帮帮我.. !!

Answer 1

但我需要以纳秒为单位的精确时间。

然后使用

int clock_gettime(clockid_t clk_id, struct timespec *tp);

它以秒和纳秒为单位返回时间

struct timespec {
  time_t   tv_sec;        /* seconds */
  long     tv_nsec;       /* nanoseconds */
};

有用的链接：

• http://linux.die.net/man/3/clock_gettime
• Use of clock_getres - newbie Linux C