[coyotos-dev] Sleep, wakeup, and persistence

[Jonathan S. Shapiro]

On Fri, 2007-09-14 at 22:53 +0200, Valerio Bellizzomi wrote:
> >That way, our embedded system can have the time punched into its
> >panel/ask some network server and eventually get an answer.  In the
> >meantime, it can be relying on the kernel for short timeouts.  A PC
> >would be able to get a good estimate of the real time from its clock
> >quickly so will be able to start servicing "real time" alarms (for lack
> >of a better word) quickly.
> 
> 
> There is a problem with that, I have a P4 mainboard that gains seconds
> faster than NTP clock.
> The mainboard clock counts faster than real time, so when NTP time is
> updated, the real time actually goes backwards.

1. This is a mis-statement
2. Get a newer Linux system.

This is a mis-statement because the issue here is a software problem. It
is true that the wall-clock time source on a PC mainboard advances at an
incorrect rate, but the error is well known and correctable.

Recent Linux system adjust time incrementally in order to avoid
non-monotonic time shifts. See "adjtime".

shap
-- 
Jonathan S. Shapiro
Managing Director
The EROS Group, LLC
www.coyotos.org, www.eros-os.org