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

David Lord snews at lordynet.org
Thu Mar 11 16:15:39 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.

I'd have no hesitation trying any of Linux, Free or NetBSD on an
atom board. Options in bios and kernel regarding power saving etc
are main concerns and would need to be disabled.

For gps refclock via serial port I'd be happy to risk NetBSD
although only atom system I have is eeepc without serial port.
With NetBSD and "via c3" with gps via serial port I really need
to be using nanosecond rather than microsecond scales on mrtg
graphs.

Lots of Linux distributions I've tried come complete with all
bells, whistles and kitchen sink, but for using other than
packaged system are to me more difficult to maintain than very
basic Slackware or similar. From what's been said in thread so
far, there are advantages to using Linux if you want to
experiment. At least for me there is very little difference
between install of Slackware, FreeBSD or NetBSD and then manual
config of ntp.conf (major decision is what editor to use, joe,
nano or vi).

cheers

David




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