Re: [chrony-dev] PPSAPI: kernel consumer

[Miroslav Lichvar <mlichvar@xxxxxxxxxx>]

On Sat, Feb 06, 2010 at 04:32:13AM +0300, Alexander Gordeev wrote:
> Do you plan to add a way to bind kernel consumer in chrony's new PPS
> driver? This is an optional feature of PPSAPI as you surely know.

I'm not sure chrony will be able to use it. If I understand it
correctly, it would need to give up control over frequency and phase
adjustments which is necessary for keeping source stats accurate.

> I've tested chrony's PPS driver and I'm really shocked with its
> synchronization quality. It is a HUGE improvement over ntpd. It was
> hard to believe that it can sync clock with a precision of 1-2us but
> it is true. However, my new kernel consumer seems to be able to keep the
> same precision, but it can sync faster (in few seconds). 

I think chrony could do that too if the kernel interface allowed a
tight loop.

This could be an extension to adjtimex which would allow us to know
either remaining singleshot adjustment (ideally in nanoseconds) or
when exactly did the last change in frequency happen.

-- 
Miroslav Lichvar

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