[ntp:questions] problem with synchronizing two comps to each other

Richard B. Gilbert rgilbert88 at comcast.net
Fri May 20 18:16:53 UTC 2005


Francesco Messineo wrote:

>Hello,
>sorry if I step in this discussion. I'm running a couple of 
>stratum 1 servers, one based on linux and the other based on 
>sparc/solaris 9. Both are synchronized to the same gps receiver (via
>a custom interface I designed, which basicly takes one rs-422 input
>and gives 2 rs-232 outputs). Here are both ntptime outputs:
>
>Linux: 
>ntp_gettime() returns code 0 (OK)
>  time c63864a2.aaecd038  Fri, May 20 2005 15:29:06.667, (.667676834),
>  maximum error 758 us, estimated error 1 us, TAI offset 1073821304
>ntp_adjtime() returns code 0 (OK)
>  modes 0x0 (),
>  offset 14.526 us, frequency -229.131 ppm, interval 256 s,
>  maximum error 758 us, estimated error 1 us,
>  status 0x2107 (PLL,PPSFREQ,PPSTIME,PPSSIGNAL,NANO),
>  time constant 4, precision 3.582 us, tolerance 496 ppm,
>  pps frequency -229.131 ppm, stability 0.013 ppm, jitter 3.225 us,
>  intervals 1394, jitter exceeded 2501, stability exceeded 32, errors 0.
>
>Solaris:
>
>ntp_gettime() returns code 0 (OK)
>  time c63864d7.676f1000  Fri, May 20 2005 15:29:59.404, (.404038),
>  maximum error 1193 us, estimated error 3 us
>ntp_adjtime() returns code 0 (OK)
>  modes 0x0 (),
>  offset 1.000 us, frequency -6.402 ppm, interval 256 s,
>  maximum error 1193 us, estimated error 3 us,
>  status 0x107 (PLL,PPSFREQ,PPSTIME,PPSSIGNAL),
>  time constant 0, precision 1.000 us, tolerance 512 ppm,
>  pps frequency 0.000 ppm, stability 0.000 ppm, jitter 1.000 us,
>  intervals 116977, jitter exceeded 509, stability exceeded 8, errors 532.
>
>I'm not very expert on how to assess these numbers, so can anyone give
>advices if things are working well and maybe if I can improuve
>something? Ntp version is 4.2.0 and the linux host runs 2.4.30+NANO
>kernel.
>
>Regards
>
>Francesco
>  
>
I'd say things are working very well indeed!  Solaris believes it's 
within 3 microseconds of the correct time and Linux believes it's within 
1 microsecond.   It's possible that you could improve the performance 
but I suspect that you would spend a great deal of money, time, and 
effort for very little gain.   If you insist, look at things like 
optimizing the serial port drivers and interrupt handling of both 
operating systems, upgrading to faster hardware, etc.



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