3 ms·

1-second-per-second is a difficult engineering challenge: https://rachelbythebay.com/w/2014/06/14/time/ https://rachelbythebay.com/w/2014/06/14/time/ (associat

1-second-per-second is a difficult engineering challenge: https://rachelbythebay.com/w/2014/06/14/time/ https://rachelbythebay.com/w/2014/06/14/time/ (associated HN discussion - https://news.ycombinator.com/item?id=8066915 https://news.ycombinator.com/item?id=8066915) Here's a choice quote from the NTP FAQ (http://www.ntp.org/ntpfaq/NTP-s-sw-clocks-quality.htm http://www.ntp.org/ntpfaq/NTP-s-sw-clocks-quality.htm): Unfortunately all the common clock hardware is not very accurate. This is simply because the frequency that makes time increase is never exactly right. Even an error of only 0.001% would make a clock be off by almost one second per day. This is also a reason why discussing clock problems uses very fine measures: One PPM (Part Per Million) is 0.0001% (1E-6). And if you want to delve into the physics, you'll enjoy this tutorial by John Vig (U.S. Army Communications-Electronics Command): http://www.am1.us/Local_Papers/U11625%20VIG-TUTORIAL.pdf http://www.am1.us/Local_Papers/U11625%20VIG-TUTORIAL.pdf

someguydave 10y ago
That might have been true awhile ago, but today you can get GPS-disciplined oscillators that can produce 1 PPS accurate down to tens of nanoseconds. By accurate, I mean "replicates what the NIST or USNO atomic clocks indicate."
someguydave 10y ago
Also your "rachelbythebay" post is discussing exactly the problem I'm trying to solve with hardware - using software. You don't need to run NTPd at all if your computer hardware and infrastructure has solved the problem of "keep my clock accurate down to 10's nanoseconds." Also, there's another unrelated problem which is "how accurately does a user process running in a linux kernel get the current time?". That's a problem no matter what kind of hardware the kernel is running on (although hardware might assist with that as well).

someguydave 10y ago

That might have been true awhile ago, but today you can get GPS-disciplined oscillators that can produce 1 PPS accurate down to tens of nanoseconds. By accurate, I mean "replicates what the NIST or USNO atomic clocks indicate."

someguydave 10y ago

Also your "rachelbythebay" post is discussing exactly the problem I'm trying to solve with hardware - using software. You don't need to run NTPd at all if your computer hardware and infrastructure has solved the problem of "keep my clock accurate down to 10's nanoseconds." Also, there's another unrelated problem which is "how accurately does a user process running in a linux kernel get the current time?". That's a problem no matter what kind of hardware the kernel is running on (although hardware might assist with that as well).