答复: [????] Re: divide error in x86 and cputime

["Li,Rongqing" <lirongqing@baidu.com>]

> That would be:
> 
>                                    minutes    days
>                                       v        v
>   9223372036854775808 / 1000000000 / 60 / 60 / 24 / 365.25 = 292.27
>                            ^               ^         ^
>                         ns -> sec       hours       years
> 
> So the report says they have threads running for a very long time, it would still
> be 292 years of run time!

Utime/rtime is u64, it means overflow needs 292.27*2=584 year,

But with multiple thread, like 292 threads, it only need two years, it is a thread group total running time


void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
{
    struct task_cputime cputime;

    thread_group_cputime(p, &cputime);
    cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
}

-Li