[RFC] Feed-Forward Clock support

[Julien Ridoux]

Hi all,

I have written a set of patches to support feed-forward clock synchronisation algorithms. To cut a long story short, this work provides support for alternatives to the NTP daemon. The RADclock daemon we developed is one of these alternatives.

This work is supported by the FreeBSD Foundation and a short project description can be found here:
http://www.freebsdfoundation.org/press/2011Aug-newsletter.shtml#Project4

The patches will be committed on the weekend of Nov 19th and suggestions and comments would be very appreciated.

The patches against r227382 can be found at this URL:
http://www.cubinlab.ee.unimelb.edu.au/~jrid/ffclock_fbsd_r227382.tar.gz

The patches introduce 3 new system calls and it is then necessary to run 'make sysent' in sys/kern and sys/compat/freebsd32.
The feed-forward support can be compiled by adding the FFCLOCK option to the kernel configuration file.

For more information, a fairly high level description of the feed-forward approach for clock synchronisation is given in this ACM Queue article.
http://queue.acm.org/detail.cfm?id=1773943

All relevant technical papers, the latest stable RADclock version and more can be found here:
http://www.synclab.org/radclock/

Please let me know your thoughts,

Thanks,
Julien