[ntp:questions] Max time adjustment

David Woolley david at ex.djwhome.demon.co.uk.invalid
Wed Oct 1 07:11:42 UTC 2008

Unruh wrote:
> David Woolley <david at ex.djwhome.demon.co.uk.invalid> writes:
>> Richard B. Gilbert wrote:
>>> ISTR that "-g" unconditionally sets the clock to whatever time is 
>>> supplied by the source(s)!  It should bring your clock to within a few 
>>> milliseconds of whatever source(s) was/were used.  This is a ONCE only 
>>> setting.  Thereafter, less drastic methods are used and the size of any 
>>> correction is subject to "sanity checking".
>> Not what the documentation (4.2.4p4) says.  It only says that it removes 
>> the 1000 second limit.
> Yes. it says exactly that. See the "this can happen only once" line. And
> the other docs which say that if ntp is off by more than 128ms it will step
> rather than slew. 

You need to consider the context of the thread.  It is not uncoditional, 
because offsets of less than 128ms do not result in a step.
>>>    -g
>>>           Normally,  ntpd  exits  with a message to the system log if the
>>>           offset exceeds the panic threshold, which is 1000 s by default.
>>>           This  option  allows  the  time  to be set to any value without
>>>           restriction;  however,  this  can  happen  only  once.  If  the
>>>           threshold is exceeded after that, ntpd will exit with a message
>>>           to  the  system log. This option can be used with the -q and -x
>>>           options. See the tinker command for other options.

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