[ntp:questions] Which version of Linux works best?

Richard B. Gilbert rgilbert88 at comcast.net
Thu Mar 11 20:55:52 UTC 2010


David J Taylor wrote:
> "Miroslav Lichvar" <mlichvar at redhat.com> wrote in message 
> news:20100311124036.GA22872 at localhost...
> []
>> I did a NTP vs chrony comparison last June with GPS 18x LVC in an
>> office environment, clock drift was moving in about 0.8ppm range. Here
>> are distributions of PPS samples received from gpsd:
>>
>> http://fedorapeople.org/~mlichvar/chrony/chrony_vs_ntp.png
>>
>> With recent chrony, NTP and kernel versions the results might be
>> different though.
>>
>> -- 
>> Miroslav Lichvar
> 
> Miroslav,
> 
> Thanks for that, a most interesting comparison, and thanks to everyone 
> for their input.
> 
> I've recently switched the old (2005) FreeBSD system back on, to see how 
> well in performs in my own environment.  From what's been said, I rather 
> suspect that were I to go for a more modern, faster, Intel Atom system, 
> any improvement in accuracy I might get could be swamped by the 
> temperature changes in the room.
> 
> There's also, I will admit, a slight doubt about the effort involved for 
> the benefit to be gained.  With Windows, I am quite happy, and 
> configuring, using or testing NTP is no problem.  With FreeBSD is seems 
> that the old PPS atom driver has gone, and I may need to configure yet 
> another driver - gpsd.  The number of variants of Linux doesn't help - I 
> only need a command-line or Telnet interface.  And remembering how long 
> it took to recompile the kernel last time, and the amount of help I 
> needed to know how to do that, also fills me with doubt.
> 
> So I suspect that the performance I'm now seeing from Windows (well 
> within 100us) may well be "good enough" for me.  Perhaps if I get more 
> free time, and a little more income this year, I may get a 
> paperback-sized Intel Atom box and see how it does.  At least some do 
> have serial ports!  And I would be most interested to hear of anyone who 
> does configure such a device.
> 
> Cheers,
> David

100 microseconds is pretty good.  Getting the time *into* a computer 
takes time and the time taken is not easy to measure.




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