Mailinglist Archive: opensuse-factory (845 mails)

[Volker Kuhlmann <list0570@xxxxxxxxxxxxxxx>]

On Sun 11 May 2008 01:04:01 NZST +1200, Carlos E. R. wrote:

> > Both are multiboot systems with the hardware clock set to local (GMT-0400)
> > time. Why are they different?

I've observed cmos clock drifts of 3s/day on recent motherboards, and
wouldn't put much mnore faith into CPU clock frequency accuracies either
(which is what the kernel time runs on while the computer is running).

> The adjtime file serves to keep track of the different speed of the 
> hardware clock (the cmos, battery, clock) when compared with an external 
> source, with the purpose of adjusting for the estimated clock drift when 
> booting the system. It is absolutely normal than different machines have 
> different drifts.

> cer@nimrodel:~> cat /otros/test_d/etc/adjtime

And each of them assumes it's the only one writing to cmos and therefore
being able to measure its clock drift. Even with a single-boot system I
didn't get high confidence in the past of this process working realibly.
Just through adjtime away completely and fetch the time (ntpdate) when
booting. Run ntp on anything turned on more than a day if you care about
the time, run ntp *always* on networked computers that may run several
days at once.

Volker

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