linux下nanosleep() & sleep()的区别

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/time.h>
#include <sched.h>
#define COUNT 1000
#define MILLION 1000000L</p><p>int main(void)
{
int i;
struct timespec slptm;
long tdif;
struct timeval tend, tstart;</p><p> slptm.tv_sec = 0;
slptm.tv_nsec = 1000; //1000 ns = 1 us</p><p> //struct sched_param param;
//param.sched_priority = 0;
//sched_setscheduler(getpid(), SCHED_FIFO, &param);</p><p> if (gettimeofday(&tstart, NULL) == -1) {
fprintf(stderr, "Failed to get start time/n");
return 1;
}
for (i = 0; i < COUNT; i++) {
if (nanosleep(&slptm, NULL) == -1) {
perror("Failed to nanosleep");
return 1;
}
}
if (gettimeofday(&tend, NULL) == -1) {
fprintf(stderr, "Failed to get end time/n");
return 1;
}
tdif = MILLION * (tend.tv_sec - tstart.tv_sec) + (tend.tv_usec - tstart.tv_usec);
printf("nanosleep() time is %ld us/n", tdif/COUNT);
return 0;
}