linux clock_gettime函數詳解

long sys_clock_gettime (clockid_t which_clock, struct timespec *tp);

which_clock參數解釋

CLOCK_REALTIME:系統即時時間,隨系統即時時間改變而改變,即從UTC1970-1-1 0:0:0開始計時,中間時刻如果系統時間被使用者該成其他,則對應的時間相應改變

CLOCK_MONOTONIC:從系統啟動這一刻起開始計時,不受系統時間被使用者改變的影響

CLOCK_PROCESS_CPUTIME_ID:本進程到當前代碼系統CPU花費的時間

CLOCK_THREAD_CPUTIME_ID:本線程到當前代碼系統CPU花費的時間

//test9.c

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

int main()
{
struct timespec time1 = {0, 0};
clock_gettime(CLOCK_REALTIME, &time1);
printf("CLOCK_REALTIME: %d, %d", time1.tv_sec, time1.tv_nsec);
clock_gettime(CLOCK_MONOTONIC, &time1);
printf("CLOCK_MONOTONIC: %d, %d", time1.tv_sec, time1.tv_nsec);
clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &time1);
printf("CLOCK_PROCESS_CPUTIME_ID: %d, %d", time1.tv_sec, time1.tv_nsec);
clock_gettime(CLOCK_THREAD_CPUTIME_ID, &time1);
printf("CLOCK_THREAD_CPUTIME_ID: %d, %d", time1.tv_sec, time1.tv_nsec);

printf("/n%d/n", time(NULL));
sleep(1);
}

如果無法編譯,預設沒有加入該庫,請用gcc test9.c -lrt運行

測試 #time ./a.out