[ntp:questions] Can NTP affect the time even when not running? (with platform details this time)

Brad Knowles brad at stop.mail-abuse.org
Wed Nov 24 15:17:04 UTC 2004

At 12:26 AM +1300 2004-11-25, Parker Jones wrote:

>  Platform: linux Fedora Core 2, kernel 2.6.8-1.521, ntp-4.2.0-7 on NEC
>  Versa LX 400MHz laptop

	Laptops are notorious for having "speed-step" type of technology 
that speeds up or slows down the processor as necessary for the 
workload and cooling requirements, and this plays holy hell with good 
timekeeping.  You shouldn't be trying to run ntpd on a laptop unless 
you lock the processor to a given speed.  It doesn't matter too much 
what speed you lock to, just so long as ntpd is given a consistent 
speed at which the CPU runs.

	If you do try to run ntpd on a laptop and you don't lock the 
processor to a given speed, you can anticipate all sorts of weird 
problems, and ntpd may calculate strange correction values which may 
be left over after you stop running it, and these values may then be 
applied inappropriately to free-running mode.

	If this isn't already in the FAQ, it should be.

Brad Knowles, <brad at stop.mail-abuse.org>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

     -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
     Assembly to the Governor, November 11, 1755

   SAGE member since 1995.  See <http://www.sage.org/> for more info.

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