[time-nuts] Is it sensible to update every few seconds from NTP server?

[Magnus Danielson]

On 08/11/12 09:14, Poul-Henning Kamp wrote:
> --------
> In message<CANX10hBat1ie0Rx_bS+X1dqGGLTPx5xCz2=tYPP_uvwGu-mosg at mail.gmail.com>
> , David Kirkby writes:
>
> If the local NTP implementation on the machine has a marginally competent
> PLL, updating more than once per minute will just increase the noise.
>
> If the local NTP implementation is really SNTP which steps the clock,
> then you should find a better one, if what you need is good timekeeping.
>

In addition, if many people ask the same server at a relatively high 
rate, it's approximating DDOS.

I'd expect that kernel FLL/PLL be included and used. Shifting from the 
default SNTP to NTP with set-only is of only marginal improvement at 
best, but with the dangerous notion that you "fixed it".

If you read up on NTP, there are articles (you find them through 
http://www.ntp.org) describing the properties of some (now old) OS 
clocks and their behaviour. Similar is to be expected for default 
Windows behaviour as well as many virtual machines. I think the old 
articles is good to raise the awareness, but I can't recall similar for 
the modern situation, but I am sure someone here have seen them.

Make sure the OS (kernel-support + NTP configuration) you are using 
provides you with the stability you need.

Does someone holds a Best Current Practice for various OSes?

Cheers,
Magnus