Messages in this thread | | | Date | Mon, 30 Dec 2013 16:11:10 +0100 | From | Oleg Nesterov <> | Subject | Re: Question about /proc/uptime |
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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().
> > > The second value isn't documented but looking at fs/proc/uptime.c I > > > think it's idle time? > > > > And this cpustat[CPUTIME_IDLE] doesn't match get_idle_time(), I guess > > it only counts ticks. > > The second value of /proc/uptime is the sum of the idle time of all cpus. > The value should roughly match the sum over get_idle_time() for all cpus. > The difference is that get_idle_time() uses arch_idle_time to add the > time for the currently running idle period as well (at least for s390).
Only if defined(arch_idle_time) ?
Otherwise get_idle_time() uses get_cpu_idle_time_us() and CONFIG_NO_HZ_COMMON makes a difference.
> That does make a difference if the cpus stay idle for long periods of > time.
Yes.
Oleg.
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