Serge Bets wrote: > Noob wrote: > >> STA_UNSYNC (0x0040, clock unsynchronized) is 0. [...] Thus the kernel >> should write the system time to the RTC every 11 minutes; but it does >> not. > > Fine! Don't touch anything, happy man, or it might well "tomber en > marche".
Hello Serge, I was hoping you'd comment! If I don't want the kernel to update the RTC, I can always undef CONFIG_GENERIC_CMOS_UPDATE. > Real men don't want the eleven-minutes mode. :-) > It is not only extremely inaccurate by itself, but it also steps on > the toes of those tools that are able to manage the RTC properly. Our equipment is supposed to run 24/7 for months / years. I need to keep the RTC synchronized, in case of power failure. Do you believe that running hwclock --systohc periodically is better than using the kernel's 11-minute mode? > I previously posted some figures, comparing the accuracy of writing the > RTC (not counting drift). Mean offset and dispersion: > > - eleven-minutes mode: -2150 µs +-5000 > - hwclock util-linux-ng 2.13.1: -2500 µs +-170 > - hwclock 2.32 from BJH: 0 µs +-10 Point taken. ( I use http://giraffe-data.com/software/about_hwclock.html ) If I use hwclock to update the RTC, how often should I do it? What do you think about the following script? while true do sleep 660 # or some other value? hwclock --utc --systohc done > Furthermore both hwclocks are able to evaluate and compensate the drift > of the RTC. The eleven-minutes mode cannot do that, and instead it can > perturbate hwclock's calculations. Is the crystal of the RTC supposed to be more stable than the crystal of the CPU? Regards. _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
