[ntp:questions] ldattach makes ttySx buffered !?

Richard B. Gilbert rgilbert88 at comcast.net
Sun May 2 19:37:38 UTC 2010

unruh wrote:
> On 2010-05-02, Richard B. Gilbert <rgilbert88 at comcast.net> wrote:
>> 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.
> Actually it is a problem for the best clock discipline, 
>  because it means that ntp also reacts very slowly to
> changes like temperature chages.

If temperature changes and the clock's reaction to them are a problem, 
there are many things that can be done to create an environment that 
will maintain a closely controlled temperature.

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