[ntp:questions] ldattach makes ttySx buffered !?

Wolfgang S. Rupprecht wolfgang.rupprecht+gnus201005 at gmail.com
Sun May 2 20:15:44 UTC 2010

"Richard B. Gilbert" <rgilbert88 at comcast.net> writes:
> 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.

Or alternately if the temperature reading were available to ntp, it
could maintain a separate drift value for each temperature.

Wolfgang S. Rupprecht
If the airwaves belong to the public why does the public only get 3
non-overlapping WIFI channels?

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