Re: [ntp:questions] Q: Disabling "11 minute mode"
[EMAIL PROTECTED] (Dean S. Messing) writes: > Serge Bets wrote: >> On Tuesday, January 22, 2008 at 19:02:23 +, Dean S. Messing wrote: >> >> > Is it possible to disable "11 minute mode" from "ntp.conf"? >> >> No. You have to tweak the kernel. If you have the PPSkit: >> >> | $ echo 0 > /proc/sys/kernel/time/rtc_update >> [...] > Thanks Serge. I looked up PPSkit. Looks good, but I'm going to have > to learn how to patch the Fedora kernel to install PPSkit. PPSkit is based on kernel 2.4. Recent changes in kernel 2.6 were dramatic regarding the time code. I'm unsure if an equivalent mechanism exists in 2.6, but it would be nice if someone would port "the pearls" to kernel 2.6. [...] Ulrich ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Q: Disabling "11 minute mode"
Serge Bets wrote: > On Tuesday, January 22, 2008 at 19:02:23 +, Dean S. Messing wrote: > > > Is it possible to disable "11 minute mode" from "ntp.conf"? > > No. You have to tweak the kernel. If you have the PPSkit: > > | $ echo 0 > /proc/sys/kernel/time/rtc_update > > Otherwise you have to patch time.c in the kernel. Dead easy, just a > matter of commenting out a line or two. I'm so patching all my kernels, > reading and writing the RTC exclusively with hwclock 2.31, and am > getting a far better accuracy. > > The main purpose of an RTC is to initialise the system time at powerup, > isn't it? Most people startup in the morning at around half a second of > the true time, and later ntpd has to step this to UTC. I routinely > startup at some low milliseconds of the true time, offset quickly > slewed. My last step event was years ago. Thanks Serge. I looked up PPSkit. Looks good, but I'm going to have to learn how to patch the Fedora kernel to install PPSkit. But I'm discovering that I have rather deeper problems on my machine (a Dell 490 Precision). Using adjtimex --compare to track the drift between system and cmos clock (ntpd not running), I see that the RTC is behaving _very_ strangely. It will begin to return screwy values after several hours of doing "adjtimex --compare" and then get to the point where "hwclcok --show" hangs. So my desire to turn off "11 minute mode" is mute when ntp is running is mute. For your amusement, here's a snippet of the output of "adjtime --compare" with an interval of 60 seconds: 1200982902 0.001784 -2.0 10001 3929312 10001 4060301 1200982962 0.0017920.1 10001 3929312 10001 3920719 1200983022 0.0020514.3 10001 3929312 10001 3646240 1200983082 0.001828 -3.7 10001 3929312 10001 4173062 1200983142 0.001756 -1.2 10001 3929312 10001 4007957 1200983202 0.0020254.5 10001 3926656 10001 3632906 1200983261 0.500370 8305.8 10001 39262889918 3549307 120098328140.001689 658355.3 10001 39262883418301130 120098334140.0019314.0 10001 3926288 10001 3661966 120098340734.001894 -10.6 10001 3926288 11001 3966652 120098346140.0016465.9 10001 39262889001 4197121 120098352140.0018904.1 10001 3926288 10001 3659882 120098360912.001763 -48.8 10001 3924640 14668 1878649 120098364140.001606 44.0 10001 39246405334 6280787 1200983741 0.001726 -64.7 10001 3924640 16668 1609118 120098376140.001911 69.8 10001 39246403334 5907090 120098382140.001553 -6.0 10001 3924640 10001 4315525 1200983921 0.001748 -63.4 10001 3924640 16668 1527086 120098394140.001894 69.1 10001 39246403334 5949798 120098400140.001554 -5.7 10001 3924640 10001 4295994 1200984101 0.001700 -64.2 10001 3921488 16668 1577580 1200984161 0.001291 -6.8 10001 3921104 10001 4367718 1200984221 0.0015324.0 10001 3921104 10001 3657823 1200984275 6.001806 14.6 10001 39211049001 3621886 120098430140.001722 55.3 10001 39203684334 6196568 120098436140.0019744.2 10001 3920368 10001 3645108 120098442734.001868 -11.8 10001 3920368 11001 4036253 120098448140.0016796.8 10001 39203689001 4126878 Things got so bad that the output eventually became: 199345540 1001658696.064552 1592732.9 10001 3879376 -5926 1725431 199345717 1001658600.500585 -1592732.8 10001 3879376 25928 6027853 199345718 1001658696.023830 1592054.1 10001 3879376 -5919335126 199345896 1001658600.500586 -1592054.1 10001 3879376 25922868985 199345897 1001658696.045414 1592413.8 10001 3879376 -5923 2975047 Before it went crazy, it had run smoothly for 5 or 6 hours. When I rebooted into the BIOS and looked at the RTC it was off by several years. This has now happened thrice, but only when adjtimex is running in the compare mode for long periods. I have no idea what this means. The cmos battery does not appear to be the problem since, after a reboot, the RTC remains at proper time indefinitely (modulo drift), unless and until I run adjtimex --compare for several hours. Anyway, thanks for the info. on "11 minute mode". Wish I could fix my RTC problem Dean ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Q: Disabling "11 minute mode"
Serge Bets wrote: : On Tuesday, January 22, 2008 at 23:13:22 +, Dean S. Messing wrote: : : > do "adjtimex -p" and look at the "status:" value. If it's odd, : > (LSB==1) then your kernel is in "11 minute mode". : : Not exactly: bit #0 set means your kernel is in PLL mode. That's bit #6 : unset that means eleven-minutes mode. The kernel does not always enter : in both modes together. Correct. Thanks for correcting this bit of mis-information. I was mis-remembering the fact that by disabling PLL mode (with the ntp "disable kernel" directive, I think) _and_ setting status bit #6, I could keep the kernel out of "11 minute mode". That was done a couple of years ago on another machine and I was confusing the two things. Dean ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Q: Disabling "11 minute mode"
On Tuesday, January 22, 2008 at 23:13:22 +, Dean S. Messing wrote: > do "adjtimex -p" and look at the "status:" value. If it's odd, > (LSB==1) then your kernel is in "11 minute mode". Not exactly: bit #0 set means your kernel is in PLL mode. That's bit #6 unset that means eleven-minutes mode. The kernel does not always enter in both modes together. Serge. -- Serge point Bets arobase laposte point net ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Q: Disabling "11 minute mode"
Hello Dean, On Tuesday, January 22, 2008 at 19:02:23 +, Dean S. Messing wrote: > Is it possible to disable "11 minute mode" from "ntp.conf"? No. You have to tweak the kernel. If you have the PPSkit: | $ echo 0 > /proc/sys/kernel/time/rtc_update Otherwise you have to patch time.c in the kernel. Dead easy, just a matter of commenting out a line or two. I'm so patching all my kernels, reading and writing the RTC exclusively with hwclock 2.31, and am getting a far better accuracy. The main purpose of an RTC is to initialise the system time at powerup, isn't it? Most people startup in the morning at around half a second of the true time, and later ntpd has to step this to UTC. I routinely startup at some low milliseconds of the true time, offset quickly slewed. My last step event was years ago. Serge. -- Serge point Bets arobase laposte point net ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Q: Disabling "11 minute mode"
David Woolley <[EMAIL PROTECTED]> writes: >Richard B. Gilbert wrote: >> >> What IS "11 minute mode"?? >If the linux kernel is told that its clock is being disciplined, it sets >the RTC from the software clock every 11 minutes. Most Unices do >something like this, although sometimes it is a cron job. Yes, it is a horrible wayto discipline the rtc. Better to measure the offset and drift and use that info when you read the rtc. You have to tell the kernel that the clock is unsynchronized ( the status byte in struct timex-- TIME_BAD If that is set, the 11 min mode is switched off. But I think youhave to keep doing it, since the kernel may decide its status is fine. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Q: Disabling "11 minute mode"
Richard B. Gilbert wrote: > Dean S. Messing wrote: > > Is it possible to disable "11 minute mode" from "ntp.conf"? > > I've tried using the command "disable kernel" but that > > appears to change the way time discipline is maintained, but > > does nothing for "11 minute mode". > > > > If using ntp.conf is not the way, what is? > > > > Thanks for your help. > > Dean > > What IS "11 minute mode"?? Oops. Sorry! I thought everyone reading this list (who could answer my question :-) would know. David Woolley gave you a good answer already so I'll only add that if you want to "see" if you are in "11 minute mode", do "adjtimex -p" and look at the "status:" value. If it's odd, (LSB==1) then your kernel is in "11 minute mode". Now, if someone would tell me how to disable it (short of hacking time.c) I'd be most thankful. I tried turning it off with adjtimex -S 64) but ntp changes it back again in a few minutes. I'd like to disable it, but keep ntp kernel discipline so I can do some analysis of my RTC. Dean ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Q: Disabling "11 minute mode"
Richard B. Gilbert wrote: > > What IS "11 minute mode"?? If the linux kernel is told that its clock is being disciplined, it sets the RTC from the software clock every 11 minutes. Most Unices do something like this, although sometimes it is a cron job. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Q: Disabling "11 minute mode"
Dean S. Messing wrote: > Is it possible to disable "11 minute mode" from "ntp.conf"? > I've tried using the command "disable kernel" but that > appears to change the way time discipline is maintained, but > does nothing for "11 minute mode". > > If using ntp.conf is not the way, what is? > > Thanks for your help. > Dean What IS "11 minute mode"?? ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
[ntp:questions] Q: Disabling "11 minute mode"
Is it possible to disable "11 minute mode" from "ntp.conf"? I've tried using the command "disable kernel" but that appears to change the way time discipline is maintained, but does nothing for "11 minute mode". If using ntp.conf is not the way, what is? Thanks for your help. Dean ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
