On Mar 10, 2010, at 7:25 AM, David J Taylor wrote: > Yes, I know it's one of those low long is a piece of string questions, but > I'm now considering a dual-core Intel Atom system, which is "Compatible with > Linux" according the the very minimal blurb I have right now. If the system > is to be used purely for NTP with Linux as a serial-port GPS/PPS stratum-1 > server (and, yes, I know dual-core isn't needed for that, but I might want to > boot Windows-7 64-bit occasionally), and considering that I know very little > about Linux, which version of Linux would the group recommend? Does it make > any difference as far as timekeeping is concerned?
The hardware you get matters much more than which OS or flavor of Linux you use; tweaking kernel compiler optimization flags matters even less. It would be good to look into the hardware you get in terms of support for HPET, p-state invariant TSC, or how good the ACPI timers are. > Two secondary questions: > - how much better might FreeBSD be than Linux? Any actual measurements? There are some nice comparisons between different platforms here: http://www.dragonflybsd.org/presentations/nanosleep/ PHK, who wrote the FreeBSD timer code, is measuring ~150 ns timekeeping precision for a stratum-1 timesource: http://phk.freebsd.dk/soekris/pps/ http://phk.freebsd.dk/pubs/timecounter.pdf You might find some threads here interesting, also: http://unix.derkeiler.com/Mailing-Lists/FreeBSD/current/2005-10/1018.html > - and one for Bill, how much better might chrony be than official NTP? Does > it have a preferred Linux, or even freeBSD? I gather that crony is intended for machines with infrequent network connections. I can't imagine trying to run it for a permanently networked stratum-1 timesource. > The system would /not/ be in a temperature controlled environment. That's unfortunate; this effects your time stability more than any other factor being considered. Well, try to make sure you get the PPS timesource working, as that will help. Regards, -- -Chuck _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
