[ntp:questions] 500ppm - is it too small?

Uwe Klein uwe_klein_habertwedt at t-online.de
Thu Nov 12 14:56:32 UTC 2009


Ulrich Windl wrote:

> IMHO, most people don't care if their clock is a few minutes off, but
> with using NTP they suddenly expect that their clock will automagically
> become as good as an atomic clock.
> 
> Ulrich

Afaics it is a question of problem resilience ;-)

A:
An off by 1000ppm xtal is not an easy reason
for exchanging motherboards with your vendor.
B:
An off by 1000ppm xtal is differently broken
from one that wanders up and down the ppm range
on changes of barometric pressure, humidity and
other whimms.

Thus if satisfying timekeeping hangs on 500ppm being
a limit the next best step is to push on the software.

"Software" as the word says is regularly the less
resilient target for problem solving ;-)

In exchange for brushing off people that ask again and
again ( with rising levels of displeasure ) the
more efficient solution would imho be to

make the ppm limit a configurable option.
or
leave the limit and introduce an offset.

produce obvious error information
when limits are reached. i.e. forex syslog

uwe









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