Re: Question about /proc/uptime

[Martin Schwidefsky <schwidefsky@de.ibm.com>]

On Mon, 30 Dec 2013 16:11:10 +0100
Oleg Nesterov <oleg@redhat.com> wrote:

> On 12/30, Martin Schwidefsky wrote:
> <
> > On Fri, 27 Dec 2013 15:45:04 +0100
> > Oleg Nesterov <oleg@redhat.com> wrote:
> >
> > > Add Frederic, I am not sure I understand this correctly.
> > >
> > > On 12/25, Rob Landley wrote:
> > > >
> > > > There are two values here, the first is seconds since boot time (which
> > > > is just elapsed time; at one point it was ajusted for suspend and that
> > > > was revered as confusing).
> > >
> > > Hmm, uptime_proc_show() still uses get_monotonic_boottime(), this should
> > > include suspend time?
> >
> > The first value of /proc/uptime is the amount of time the system has been
> > running, the sum of the suspend time is not included.
> 
> Hmm. It uses get_monotonic_boottime() and this helper adds
> timekeeper->total_sleep_time to the returned value? Even the comment says
> 
> 	* This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
> 	* includes the time spent in suspend.
> 
> > timekeeping_resume()
> > is supposed to take care of that.
> 
> Not sure I understand... except that timekeeping_resume() does
> __timekeeping_inject_sleeptime().

Hmm, you are right. The sleeptime is added to the monotonic boottime. 
So the first value of /proc/uptime is the wall-time since boot.
And the second value is combined idle time over all cpus.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.