[ntp:questions] Power-saving patch to NTP

Martin Burnicki martin.burnicki at meinberg.de
Mon May 19 08:48:21 UTC 2008


Hi Uwe,

Uwe Klein wrote:
> Hi Martin,
> 
> Martin Burnicki wrote:
> 
>> The next releases (i.e. v4.2.4p5 and v4.2.6) will support interface
>> changes much better than older versions, at least after startup.
> 
>> Unfortunately Linux uses an implementation of network sockets which
>> differs from the implementation in other Unices, so ntpd does not receive
>> notifications on interface changes under Linux. Instead, ntpd has to scan
>> the interfaces in certain intervals to see if something has changed.
> polling is imho the least pleasant solution. 

Agreed. However, you can at least configure the dynamic interface scan
interval using the -U parameter, so you can decide if you prefer short
response times or a longer response time with maybe decreased power
requirements.

> The trend (in linux) is 
> towards waiting on events/signaling.

That's what the network routing socket support would do (I think this is
called the netlink layer under Linux). However, "someone" would have to
implement this for Linux, and also for Windows. See:

https://support.ntp.org/bugs/show_bug.cgi?id=992 (Linux)
https://support.ntp.org/bugs/show_bug.cgi?id=991 (Windows)

> IMHO having ntp react to signaling of some  kind or other would suffice.
> 
> d-bus or the if-up if-down scripts should be able to give all the
> information wanted?

AFAIK this would currently only be possible by adding/removing upstream
servers via ntpdc, which can be run from the if-up if-down scripts. I'm not
sure where this had to be done if the network manager is used instead of
if-up/if-down, e.g. in openSUSE.

Supporting d-bus would also require some Linux-specific code which had to be
written by "someone".


Martin
-- 
Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont
Germany




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