"Dave Hart" <daveh...@gmail.com> wrote in message news:98c443b7-15b4-4472-b985-9c3e99788...@j9g2000prh.googlegroups.com... > On Dec 11, 6:31 pm, "David J Taylor" wrote: >> I note that the line: "using Windows clock directly" appears in >> Gemini >> and not Stamsund, and that "HZ 64.000 using 43 msec timer 23.256 Hz 64 >> deep" appears in Stamsund and not Gemini. Stamsund also has >> "NTP_USER_INTERP_DANGEROUS=1" which must have been a hangover from our >> earlier experiments. > > So it seems. You may be the only person to use that environment > variable (though I'm pretty sure it's not spelled quite right there). > >> Perhaps this means I'm running Stamsund in a non-standard mode, without >> having remembered I was, and what is the significance that it appears >> to >> work well as a reference server (although nothing like as well as on >> Windows XP)? > > It's actually very interesting to me, and I'm glad you reminded me of > it. It raises the question why is it interpolation is not horribly > broken on this system with a 1ms resolution system clock, given that > we know the scheduler resolution on all the known Windows versions is > 1ms? I thought the problem that broke interpolation on Win7 and Vista > systems with the system clock precision driven to 0.5 or 1ms was > caused by the sampling of clock and counter pairs occurring in phase > with the clock updates, because the interpolation scheme wants it > samples well-distributed so there is always at least one sample in the > last second or two that happened to be taken soon after the clock > ticked to a new value. > > The fact that is working despite the 1ms system clock means I don't > understand the breakage as well as I thought, and hints of a > possibility interpolation could be made to work on more or all Vista/7 > systems. > > Cheers, > Dave Hart
Dave, It isn't spelt correctly - I was walking from one system to another and remembering the string in my head (a mistake!). It's actually: NTPD_USE_INTERP_DANGEROUS=1 on a second check (give or take more walking errors). The major difference between the two systems is that one has a ref-clock attached and the other doesn't. Plus, as you noted, HAL and hardware differences. I can test any 4.2.7 you want to pass me on both the LAN-synced Vista PC (which has these apparent "server received after transmitted timestamps") and the GPS-PPS-kernel-serial Windows-7 system, although I would prefer not to have to reboot if at all possible. I could easily remove the ref-clock from the Windows-7 system (Stamsund), and the lead might then stretch to the Vista system (Gemini). Cheers, David _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions