[ntp:questions] Q: Disabling "11 minute mode"

Unruh unruh-spam at physics.ubc.ca
Tue Jan 22 23:41:53 UTC 2008


David Woolley <forums at david-woolley.me.uk> writes:

>Richard B. Gilbert wrote:

>> 
>> What IS "11 minute mode"??

>If the linux kernel is told that its clock is being disciplined, it sets 
>the RTC from the software clock every 11 minutes.  Most Unices do 
>something like this, although sometimes it is a cron job.

Yes, it is a horrible wayto discipline the rtc. 
Better to measure the offset and drift and use that info when you read the
rtc. 
You have to tell the kernel that the clock is unsynchronized ( the status
byte in struct timex-- TIME_BAD
If that is set, the 11 min mode is switched off. 
But I think youhave to keep doing it, since the kernel may decide its
status is fine. 





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