F10: PC clock lacking behind with 20 minutes

[Dr. Michael J. Chudobiak]

Alexander Todorov wrote:
> Since yesterday the result is:
> 1) set bios time to the correct value
> 2) booted the system and turned off ntp
> 3) left the system running for several hours then shut it down
> 4) turned it on today and the clock drift is less than 5 minutes. Much 
> better than 20 minutes.
> 
> See earlier post on this thread by Michal Jaegermann. He's also seeing 
> similar problems.

ntp is limited to fixing drifts of 500 ppm (0.05%). If the clock drift 
is higher than that for some reason, it can't fix it. I had a system 
where I had to manually tweak the "tick rate" by adding this to 
/etc/rc.local:

/sbin/adjtimex --tick=10195

where "10195" was relative to the expected "10000" tick rate, and had to 
be determined by measuring the actual drift rate. A kernel upgrade 
eventually made this unnecessary. (This could happen if the kernel had a 
flaw that caused timer interrupts to be missed regularly, for example).

I don't know if this is your problem, but maybe it will help...

- Mike