Dave Hart wrote: > On Mar 2, 1:46 pm, "David J Taylor" <david-tay...@blueyonder.neither- > this-bit.nor-this.co.uk> wrote: >> >> Folks, >> >> Dave Hart asked that I post this information: >> >> Very briefly, I happen to have a 100Hz system, and have been playing >> with the improved version of ntpd.exe on a Windows 2000 system. >> Working with Dave, we found that it did have some issues, and it >> seems that these issues have probably been resolved by setting the >> sample interval to 26 milliseconds instead of the default 43 >> milliseconds. > > After seeing the performance of David Taylor's Windows ntpd with a > refclock on a 100 Hz system was not doing as well as my 64 Hz system, > David spent a chunk of time testing all the intervals from 26 through > 32 on his system and noting the jitter over a few minutes. He found > that 27 was the best NTPD_INT_INT value for a 100 Hz system of those > tested. David, would you mind posting your results in case anyone > else wants to try more intervals and do so comparably?
Yes, Dave. Here are the results: _____________________________ Using the interactive start of ntpd.exe, I ran for a couple of minutes first (waiting for a 377 in the Reach field), then sampled the reported Jitter values from an "ntpq -p" at about half-minute intervals, with each INT value. 26 - jitter = 0.040 0.034 0.123 0.052 0.044 27 - jitter = 0.034 0.032 0.046 0.050 0.042 28 - jitter = 0.043 0.060 0.065 0.069 0.033 29 - jitter = 0.090 0.072 0.045 0.153 0.059 30 - jitter = 0.508 0.255 0.253 0.223 0.249 31 - jitter = 0.070 0.066 0.059 0.071 0.065 32 - jitter = 0.085 0.048 0.058 0.070 0.029 I wondered if the VNC remote control might be affecting the results, so I tried repeating the 27 with and without: 27 with VNC - jitter = 0.034 0.032 0.046 0.050 0.042 27 without VNC - jitter = 0.034 0.040 0.063 0.050 0.025 So it looks as if the VNC wasn't affecting the result. _____________________________ This was with an old Windows 2000 Server PC, a 550Mhz Pentium III, so I wasn't expecting great results. The current timekeeping can be seen here, and you can see that going from zero to near 100% CPU load has upset the timekeeping. http://www.satsignal.eu/mrtg/performance_bacchus.php All my PCs are shown here: http://www.satsignal.eu/mrtg/performance_ntp.php Cheers, David _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
