jiffies64_to_nsecs
cur_wall_time = jiffies64_to_nsecs(get_jiffies_64());
cur_nsecs = jiffies64_to_nsecs(get_jiffies_64());
rcpu->prev_wall = jiffies64_to_nsecs(get_jiffies_64());
extern u64 jiffies64_to_nsecs(u64 j);
EXPORT_SYMBOL(jiffies64_to_nsecs);