[ntp:questions] ntpd and hw clock
unruh-spam at physics.ubc.ca
Fri Feb 27 17:37:20 UTC 2009
Steve Kostecke <kostecke at ntp.org> writes:
>On 2009-02-27, Nero Imhard <nim at pipe.nl> wrote:
>> Unruh schreef:
>>> Well, there is that silly 11min setting of the kernel, which tried to reset
>>> the rtc every 11 min if it decides that the kernel is synchronized.
>> Silly indeed, but rather Linux-specific. No such kludge in FreeBSD afaik.
>Why do you consider a periodic update of the RTC to be a kludge?
Because it does not allow one to determine the frequency offset of the rtc,
info which can be used to improve the starup accuracy of the system from
the rtc. This is supported by both chrony and by the new (non-utils)
hwclock. The 11 min mode completely destroys that. It would be like
instituting a procedure by which ntp polled the external sources and simply
reset the clock each time it found an offset.
>Steve Kostecke <kostecke at ntp.org>
>NTP Public Services Project - http://support.ntp.org/
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