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

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

On Fri, Mar 06, 2015 at 06:11:25PM +0100, Miroslav Lichvar wrote:
> The trouble is the raw mode is not a filter that can be easily
> plugged in, it has a different input than servos. It's a fundamentally
> different approach in how are the timestamps handled. In the raw mode
> we use only the last four timestamps, in filtered mode we use the last
> two timestamps and a long term average of delays from past sets of
> four timestamps.

We can really rework clock.c to make it cleaner to implement this sort
of thing.  We don't have to store t1-4 in the struct clock at all.

Why not abstract the offset estimator:

		   +-------------+
              t1 --|             |
              t2 --|  offset     |
              t3 --|             |-- offset
              t4 --|  estimator  |
  smoothed delay --|             |
		   +-------------+

There has got to be a nicer way to arrange the code to make this
work.  Once we add a "balanced mode" that works better in some
situations, people will want other balanced mode algorithms.

Thanks,
Richard