nemo_outis wrote: > ... >> Instead I see what looks like a religion, where questions are treated as > apostasy or treason.
Sycophancy is common on internet forums. In this particular case, my view is that any clock that is out by more than 500ppm has something fundamentally wrong with it that should be addressed before trying to run time discipline software on it. If the actual hardware clock is out by this much, there is a good chance that it is not being effectively disciplined by its crystal and will be very unstable. If the machine is losing clock interrupts, that needs to be fixed, avoided (e.g. by using a sustainable clock interrupt frequency), or compensated for by OS specific code. If the clock frequency calibration is unreliable, it needs to be fixed (e.g. remember from startup to startup, use a longer baseline for the calibration, or ensure that the calibration is done on a quiet system). As Unruh says, some of the things that need doing to ntpd to improve its real world performance are so radical, that the result would not be a conforming implementation of NTP. One of the key issues is that NTP clients can also be NTP servers, so behaviour difference have network wide implications. When using conforming NTP algorithms, I believe that certain parameters have been set on the basis that nowhere in the trail back to stratum 0 will you find a machine that is slewing at faster than 500ppm (presumably plus an allowance for a reasonable static clock error). One could probably keep the standard NTP algorithms and parameters and permit a faster slew at start up, but one would need to refuse to act as a peer or server until confidence had been built that one had a good estimate of the static error. From then on one would have to report the frequency offset from that value, not from the boot time value provided by the kernel, i.e one would do ones own once per session frequency calibration. As I suspect many people with bad clocks only want leaf node client operation, in spite of the contra-indication of having a local clock configured, for many people having a leaf mode only mode which removed slew rate restrictions might be acceptable. Technically, such implementations are SNTP, rather than NTP, even if they retain some of the NTP algorithms. _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
