RTC error and temperature (was Re: RFC: proposed changes to hwclock)
On Sat, 12 Feb 2000, Dylan Paul Thurston wrote:
> On Sat, Feb 12, 2000 at 12:05:47AM -0200, Henrique M Holschuh wrote:
> > On the other hand, it _is_ feasible that a normal RTC would change drift
> > direction if the temperature varies enough and the RTC drift is close to
> > zero. One would need to do field tests to verify if this is common or not (I
> > just thought of laptops. They are subject to variations of 10, sometimes 20
> > degrees Celsius in certain places/seasons...)
>
> I'm running on a laptop, which does have significant temperature variations.
Please notice that fast temperature variations should not be a big problem.
Keeping the laptop for a while in very different ambient temperatures is (as
the RTC is running even when the machine is suspended/turned off, and thus
would run for a while in different frequencies).
> I'm not sure how to best test clock variations, though; I'm running xntp.
> Is it easy to log the drift rate?
Yes, ntp (version 4, at least. xntp is version 3 I think) will record
everything you might want to know about your clock if you configure it
accordingly. See the html docs for "driftfile", "statsdir", "statistics" and
"filegen".
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
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