[ntp:questions] Power-saving patch to NTP

Uwe Klein uwe_klein_habertwedt at t-online.de
Mon May 19 09:05:52 UTC 2008


Martin Burnicki wrote:
> 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.
push a trigger for this into ntpdc?
> 
> 
>>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.
No idea, networkmanager is rather new to me ( you can still select between
if-up/down/networkmanager while configuring interfaces)
> 
> Supporting d-bus would also require some Linux-specific code which had to be
> written by "someone".

Yeah, right, one just can't get rid of human intervention ;-)
( I have been thinking about a d-bus package for tcl...)

A question:
what would happen if one throws out binding to select interfaces and
instead pushes this out to the firewall/ip-tables infrastructure?

> 
> 
> Martin
uwe




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