Hi
> 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 extreme myself. Bob > > 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. > > -Ruslan > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
