Timekeeping [Was: Re: cvs commit: src/usr.bin/vmstat vmstat.c src/usr.bin/w w.c]

[Andre Oppermann]

Marcel Moolenaar wrote:
> 
> On Oct 21, 2005, at 9:05 AM, Poul-Henning Kamp wrote:
> 
> > In message <20051022011020.T5554 at delplex.bde.org>, Bruce Evans writes:
> >
> >
> >
> >> How do you resync laptops after suspending them for long enough for
> >> the clock to drift?  Use ntpd and let it step, or use ntpd -x and let
> >> it take hours to resync?  The right thing to do is step the clocks to
> >> the current time immediately so that they are correct while the
> >> system
> >> is actually being used.
> >>
> >
> > Ahh, and now we get into interesting territory:  What _is_ the
> > definition of uptime for a laptop which has been suspended ?
> 
> I don't think the definition has to change, but I don't know what
> the *exact* definition of uptime is. Wikipedia says this:
> 
> "Uptime is a measure of the time a computer system has been up and
>   running. It came into use to describe the opposite of downtime,
>   times when a system was non-operational."
> 
> Given this, suspend is downtime and the uptime is therefore defined
> as the amount of time since resume.
> 
> Doesn't seem unreasonable to me.
> 
> > Again, if you have been sitting in DDB, what exactly is the definition
> > of "uptime" ?
> 
> Since the kernel is non-operational while in DDB, uptime is to
> reset when leaving DDB. Again, according to the Wikipedia definition
> of uptime. I'm having more problems finding this reasonable, but
> it's not unacceptable.
> 
> The question therefore is: which definition of uptime do we try to
> implement?

The question is "up and running" since when?  Since the last
interruption (suspend or ddb) or since the last initialization
of the kernel (boot or reboot)?  IMO the latter minus the former
in SI seconds.

-- 
Andre