[ntp:questions] Flash 400 on all peers; can't get ntpd to be happy

Ralph ralph at depth.net
Sat Mar 12 05:24:51 UTC 2011


I appreciate the offer to help.

I've been thinking about this problem a while and here are my thoughts... It 
seems to me that ntpd has the goal of keeping extremely accurate time - which
 is important for many obvious reasons.  However there are those of us that
don't need time accurate to the millisecond and / or don't need time to be 
perfectly in sync with the rest of the world.

With that in mind, it would be nice if there was something out there that 
operated in a slightly different mode than ntpd does... It appears that the 
problem that ntpd has is that because the distance between ticks on the local 
machine are variable and therefore calculating the time between a transmission 
and receipt is 'impossible'.  But why not have something that assumes that 
the local ticks simply can't be trusted?  Keep track of how far off the local 
clock is from the ntp sources (averaged over numerous queries) and adjust the 
clock based on the average adjustment that is needed.  Don't mess with trying 
to calculate the time taken for the round trip and all that, if the replies
back from servers are within a certain amount of time of one another, then just
average them out.  

If you do something similar to what I suggest, you will end up running further 'behind' than a ntpd server that has consistent ticks, but you ought to
at least be able to have something that disciplines the clock into running 
fairly close to real time on average and stays within a handful of seconds 
within 'real' time.

As I said, this probably is a completely different solution than ntpd, but it 
seems like it would be really useful for people that are more concerned with 
making time consistent / realistic than they are with making it ultra-accurate. 
And this could also be very useful for people that have hardware clocks that 
don't seem to run consistently enough for ntpd - the people whom I've seen been 
told to replace their motherboard in order to get a clock that can keep time.

I'm no time expert, so feel free to explain where I've lost my mind if I'm not 
thinking through this all the way...

More information about the questions mailing list