On 2015-06-03 10:55 AM, Poul-Henning Kamp wrote:
Oh great! On quick glance that's just the sort of RT discussion I was interested in. I'll study it more.--------In message <556f0c92.4020...@edlmax.com>, Brooks Harris writes:You're saying this to the bloke who implemented a prototype adaptive optics solution for the ESO ELT on a plain, unmodified FreeBSD kernel ?I didn't know that, very impressive. Is there information anywhere how it was done?I did a presentation at a workshop at ESO in december 2012, the slides seems to be here: https://www.eso.org/sci/meetings/2012/RTCWorkshop/proceedings.html
I'm not sure what the legal status is for deeper info. You'd have to ask them for access. The person to talk to is Nick Kornweibel.
And dig deeper when I can.
Yes, right, as I said, if not so clearly, "some sort of hardware assist". In my land we have things like SDI, perhaps on PCI, feeding video/audio in "real-time", or "device control" (remote control of video/audio devices) protocols that arrive at serial ports (COM or USB or something) in "real-time". Those sources often have high quality oscillators and timebases and the protocols support deterministic delivery to the port. You then have to carefully interface through worker threads and buffers to hang the timestamps on the video/audio samples, etc. That can be tricky, and often involving the manufacture's NT device drivers (some work better than others!), or you may need to build a driver yourself, notoriously tricky, but down there you can get really close to the metal (ring 0) if you're careful. But its never an RTOS.I bring the RT aspect [...]The first point here is that commodity *NIX, be it LINUX, FreeBSD or something else is often used to pull time into systems, even if they themselves don't do the RT part.
The other thing to notice is that even if it is not RT in the strict classical sense, commodity *NIX does things which matter on microsecond resolution timescales. (As for instance the ESO thing).
Right. Thanks,
The time on Microsoft Azure will be Different by a second, everywhere http://www.theregister.co.uk/2015/05/29/windows_azure_second_out_of_sync/ As I said earlier - A) Where did they get this information? B) Is it true? C) Is that how Windows is behaving?A) Ask them.
Can try.
(M$ probably notified their customers ?)
They did - How the Windows Time service treats a leap second https://support.microsoft.com/en-us/kb/909614
B) I have no reason to doubt it. The Reg is usually very good on truth.
I doubt it now -"Contrary to one post I recently read, Microsoft doesn’t implement a leap second time zone by time zone – in other words, in a rolling fashion, like the way we watch new year celebrations count down around the world. Essentially, the leap second occurs at the same time everywhere."
Another look at the impact of the coming 2015 leap second (not much)http://blogs.msdn.com/b/mthree/archive/2015/06/01/2015-leap-second-060115.aspx
Also How the Windows Time Service Works https://technet.microsoft.com/en-us/library/cc773013(v=ws.10).aspx
C) Probably only in Azure.
As above, I doubt it.
Other Windows will probably do the
usual Windows thing: Step a second some time later.
Leap Seconds are not the only thing might upset the apple cart - Summary of Windows Azure Service Disruption on Feb 29th, 2012 http://azure.microsoft.com/blog/2012/03/09/summary-of-windows-azure-service-disruption-on-feb-29th-2012/ -Brooks
_______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
