[ntp:questions] ldattach makes ttySx buffered !?

Richard B. Gilbert rgilbert88 at comcast.net
Sun May 2 13:42:56 UTC 2010

Wolfgang Breyha wrote:
> Hi!
> I'm running a soekris net4801 with openwrt 10.03. kernel with
> LinuxPPS patch and ntpd 4.2.6p1.
> Today I recognized that my /dev/ttyS1 gets a input buffer as soon as I run
> ldattach PPS /dev/ttyS1
> The buffer is hold until somebody connects to /dev/ttyS1 and reads it. This
> is reproduceable with "cat" at any time.
> ntpd gets confused by the input at start big time and needs really long to
> settle.
> I have not found the cause of this yet. Has somebody noticed similar behaviour?
> Greetings, Wolfgang

NTPD has always needed a long time to settle.  From a cold start you 
need to wait ten to twelve hours for the time to reach the best possible 
accuracy!  This is not a great problem if you keep NTPD running 24x7.

For those who need/want to turn NTPD on at 0830 local time and turn it 
off at 1700 local it's a real problem to which the only solutions are: 
to suffer, to run 24x7, or to use a tool better suited to the circumstances.

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