Hi My concern would be a really bad driver that spikes into the 1,000's of us every so often. Every once in a great while there could be a collision. That would really drive you crazy trying to find it.
Bob On Jun 18, 2011, at 10:04 AM, David J Taylor wrote: >> Hi >> >> DPC Latency = Deferred Procedure Call Latency = how long it takes Windows to >> get around to doing what it should do real time. Put another way - how lazy >> is your computer? >> It may not be a big issue, but it's probably worth checking for free: >> http://www.thesycon.de/deu/latency_check.shtml >> We don't do audio or video since we're serious Time Nuts:)... The same issue >> would mess up our stuff though. It certainly would be useful to know when >> playing with NTP. >> Usual disclaimer - if your PC explodes don't blame me. There are lots of >> other programs out there that do the same thing. I have no connection with >> these guys. It's just the first one I found. >> >> Bob > > Bob, > > Yes, that's a program which produces some interesting results, and has been > useful for detecting bad behaviour by some poorly written drivers (e.g. when > receiving masses of data over a satellite DVB link). > > For NTP, I think you may find that all the time-critical stuff is done at > high-priority, and it's only the non-time critical stuff which is done at DPC > time. This is how the DPC is intended to be used, of course. VMS has a > similar mechanism, ASTs, if I recall correctly, but that was a long time ago. > > On Windows with NTP, you can get within a couple of hundred microseconds (XP) > or perhaps 50 microseconds (Windows-7) if my graphs here are any guide: > > http://www.satsignal.eu/mrtg/performance_ntp.php > > The best I can offer is within 10 microseconds or so on an Intel Atom system > running FreeBSD. I'm sure that others can do better! > > Cheers, > David > -- > SatSignal software - quality software written to your requirements > Web: http://www.satsignal.eu > Email: [email protected] > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
