linux内核中添加时间函数

//添加的头文件
# include 
# include 
# include 
# include 
# include 



//具体方法：
printk("-*- before read page,timestamp:%lu\n",gettime());
ret = copy_page_to_iter(page, offset, nr, iter);
printk("-*- before read page,timestamp:%lu\n",gettime());
		
//【注意】：该方法包含了printk的时间



//改进方法：
unsigned long time1,time2;      /* offset into pagecache page */
		
time1=gettime();
ret = copy_page_to_iter(page, offset, nr, iter);
time2=gettime()

printk("-*-time:%lu\n",time2-time1);