在内核获取时间 精度纳秒级

原文地址：http://blog.chinaunix.net/uid-20583479-id-1920140.html

程序代码：
    struct timespec ts;
    ts = current_kernel_time();
    printk(KERN_ALERT "%ld %ld\n", ts.tv_sec, ts.tv_nsec);
   
    struct timeval tv;
    /*获取时间*/
    do_gettimeofday(&tv);
    printk(KERN_ALERT "now: %ld %ld\n", tv.tv_sec, tv.tv_usec);
    /*设置时间， 时钟调后5小时*/
    ts.tv_sec = tv.tv_sec + 3600*5;
    do_settimeofday(&ts);
    printk(KERN_ALERT "after 5 hours: %ld %ld\n", tv.tv_sec, tv.tv_usec);

输出日志：

Jun 30 23:17:29 localhost kernel: now: 1309447049 608761
Jun 30 23:17:29 localhost kernel: after 5 hours: 1309447049 608761
Jun 30 23:18:13 localhost kernel: Goodbye, cruel world
Jul  1 04:18:22 localhost kernel: Hello, world
Jul  1 04:18:22 localhost kernel: 1309447102 738475231
Jul  1 04:18:22 localhost kernel: now: 1309447102 739073
Jul  1 04:18:22 localhost kernel: after 5 hours: 1309447102 739073