Re: [Linuxptp-devel] [PATCH RFC 0/6] Improve accuracy with software timestamping

[Richard C. <ric...@gm...>]

On Fri, Feb 13, 2015 at 01:56:12PM +0100, Miroslav Lichvar wrote:
> These patches should improve the synchronization of the clock with
> larger jitters, e.g. with software timestamping, wireless networks,
> etc.

What kind of networks did you test this on?

> What do you think? Does this make sense?

This code pairs up the Sync measurement with the most recent Delay_Req
measurement.  The assumption here is that a randomly larger Sync delay
will be paired with a larger Delay_Req delay (if I understood).  But
that is not a valid assumption in general, is it?

I think the best way is to simply leave out (ignore) bad measurements
altogether.  This is what the mean filter does, and the servos are
supposed to mitigate the effects of outliers.

Overall, I wouldn't mind having extra filter options for noisy
networks.  Ideally this would be modular, just like the servos and
filters are now.  People have asked about discarding software
timestamping measurements that are too far out.

Come to think of it, can't your algorithm be implemented within the
current servo/filter modular architecture?  We can change the API to
provide t1, t2, t3, and t4.

Thanks
Richard