> On Feb 16, 2017, at 1:30 AM, Ruslan Nabioullin <rnabioul...@gmail.com> wrote:
> On 02/15/2017 01:17 PM, Chris Albertson wrote:
>> Why set up a dedicated NTP server if you only have two computers
>> that will use it? Your server will be accurate to a few
>> microseconds but your two computers will only by good to a few
>> milliseconds because ethernet is not nearly as good as PPS.
> Well Ethernet can be *extremely* accurate if PTP is used (a whitepaper
> specifies <= 100 ns accuracy if the LAN is optimized for it).
PTP single shot over ethernet is not at the < 100 ns level, even with proper
cards. In real world settings, the traffic level for sub
100 ns PTP can be pretty high. Some situations appear to require > 100K
transactions per second. I’ve never seen anything quite that
> Well, the assumption here is that one would render this service available to
> the public, registering the server(s) with the NTP website and/or the NTP
> Pool Project; n.b. this is still possible for connections lacking a static IP
> address, by means of an IPv6 tunnel, available at no cost from at least one
> vendor. Otherwise yes, by some perspectives it can be considered quite
> pointless and wasteful to operate dedicated servers, standards, receivers,
> etc. with no means of time transfer to customers.
> > NTP is almost zero load on the CPU and the best thing is the NTP
> > accuracy is not effected by CPU load SO you can run other service
> > without degrading the NTP server.
> Well n.b. TVB's hardware PPS timestamping post. Also WWV and CHU decoding by
> NTP's modules can be problematic, as well as the obvious case of the server
> being overloaded. Finally note that based on others' experimentation, the
> motherboard's XO temperature is nontrivially-highly correlated with CPU load,
> so for better motherboard XO-based holdover performance, once must create an
> ersatz oven utilizing the CPU(s), by running them at full utilization
> (obviously with proper scheduling priority), so typically volunteer
> distributed computing project(s) such as BOINC (SETI@home, etc.),
> Folding@Home, etc. Of course then power consumption becomes problematic.
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