On 2012-06-06, Julien Ridoux <[email protected]> wrote: > On Wednesday, June 6, 2012 4:41:59 PM UTC+10, unruh wrote: >> On 2012-06-06, Harlan Stenn <[email protected]> wrote: > Dear unruh (Dr. William Unruh?), > > It seems there is a little misunderstanding, I hope you won't mind some > clarification.
Of course not. > > The article you keep quoting is a high level description of the work, and we > have worked with ACM Queue editor and reviewers to provide an overview easy > to grasp for the non-expert. This was what ACM Queue was after. Please view > this article that way and not as a scientific paper. I believe you are well > aware of synchronisation issues, and I understand your reaction, but again, > you were not the targeted audience (and for what it is worth, yes, we also > have cheap GPS receivers on our office window that took less than 15mn to set > up). But high level descriptions should not be puff pieces. > > I would encourage you to read the scientific papers we published. I am > confident you will see the level of hype being much lower. The description of > the algorithm you are requesting can be found in several papers. Repeating > myself, the main one being : ""Robust Synchronization of Absolute and > Difference Clocks over Networks". It does describe the algorithm in more > details. It may not deliver all the details you are after (or be slightly > outdated), but the code publicly available is also there for you to read. It > is the ultimate reference after all. > It would be nice to have a link to that publication, in particular not not one where you have to buy it. And asking people to read the code is a cop out. I have tried hard to read the ntpd code for example, and the chrony code. While the latter is slightly (only sightly) better than the former, both are a real pain to figure out what is going on. Reading code is always a case of far fr too many trees for to see the forest. For others, I have found a copy at http://www.cubinlab.ee.unimelb.edu.au/~darryl/Publications/synch_ToN.pdf > It was not my intention to describe the entire algorithm in my previous > message (it has been done in publicly available papers), but instead give > some pointers and general answers to some of the questions raised earlier. My > message did not intend to sparkle a heated discussion but instead try to > provide honest answers to this group. I am very confused by your graph comparing ntpd to radclock. The ntp has huge oscillations while from what I have read it is critically damped while what I see is a pretty high Q (of the order of 10 or so) in the graphs. Things I have not seen in my looks at ntpd. (Ntpd does have problems which I have spent time pointing out in the comparison with chrony) but oscillations like that I have not seen. Is this really ntpd or some stripped down testbed? > > I am happy to receive criticism from people who have interest in improving > computer clock synchronisation. Please accept my apologies if my message > offended you, I am sure we can pursue this discussion over a more private > channel in a constructive way. _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
