Jonathan Lim wrote:
> On Sat Aug 25 21:58:44 2007, [email protected] wrote:
>>> Also, I don't understand why the code to update btime:
>>>
>>> /* calculate task elapsed time in timespec */
>>> do_posix_clock_monotonic_gettime(&uptime);
>>> ts = timespec_sub(uptime, tsk->start_time);
>>> ...
>>> stats->ac_btime = get_seconds() - ts.tv_sec;
>>>
>>> does not simply use tsk->start_time or tsk->real_start_time without
>>> comparing it to the current time.
>> From what I understand, task->start_time and task->real_start_time
>> are taken from the realtime clock. The accounting in CSA seems
>> to be very similar to the accounting done in do_acct_process()
>> (kernel/acct.c).
>
> In CSA 3.0 ...
>
> csa_acct_eop(int exitcode, struct task_struct *p)
>
> csa->ac_btime = boottime +
> ((p->start_time.tv_nsec < NSEC_PER_SEC/2) ?
> p->start_time.tv_sec :
> p->start_time.tv_sec +1);
>
> where
>
> do_posix_clock_monotonic_gettime(&uptime);
> boottime = xtime.tv_sec - uptime.tv_sec;
>
> In an upcoming version of CSA ...
>
> csa_acct_eop(struct taskstats *p)
>
> csa->ac_btime = p->ac_btime;
>
> where
>
> do_posix_clock_monotonic_gettime(&uptime);
> ts = uptime - tsk->start_time;
> p->ac_btime = get_seconds() - ts.tv_sec;
> = xtime.tv_sec - (uptime - tsk->start_time);
> = (xtime.tv_sec - uptime) + tsk->start_time;
>
> So they're basically equivalent.
Excellent, so can Guillaume change ac_btime to be just tsk->start_time?
--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL
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