[LinuxPPS] ntpd synchronization issues

[Felix Joussein]

  What if I disable ACPI in the kernel?


Am 2010-08-08 19:37, schrieb Hal V. Engel:
> On Sunday 08 August 2010 09:55:08 am Felix Joussein wrote:
>>    Hi Udo,
>> What kernel version?
>>
>> Current Stable (2.6.34)
>>
>> What ntpd version?
>>
>> The source, which is shipped with Ubuntu 10.04 which is 4.2.4p6.
>> I build the source using: --enable-all-clocks --enable-ATOM
>> --enable-parse-clocks --enable-accurate-adjtime --with-crypto
>>
>> What refclock?
>>
>> here's my ntp.conf:
>>
>> # refclocks
>> server 217.19.37.20 iburst minpoll 4 maxpoll 4 prefer
>> server 217.19.37.26 iburst minpoll 4 maxpoll 4 prefer
>> server 217.19.37.27 iburst minpoll 4 maxpoll 4 prefer
>>
>> # PPS0
>> server 127.127.22.0 iburst minpoll 4 maxpoll 4 prefer
>> fudge  127.127.22.0 stratum 0 refid ATOM flag3 1
>>
>> # PPS1
>> server 127.127.22.1 iburst minpoll 4 maxpoll 4 prefer
>> fudge  127.127.22.1 stratum 0 refid ATOM flag3 1
>>
>> driftfile /var/lib/ntp/ntp.drift
>> keysdir /etc/ntp
>> crypto randfile /var/lib/ntp/.rnd
>> crypto pw leapsecreet
>>
>>
>> Any patches for kernel or ntpd?
>>
>> Kernel: No
>> ntpd: probably the Ubuntu patches
>>
>>
>> But: I have had the same problem over the last year with kernel versions
>> prior to 2.6.34 and ntpd source from ntpd.org
>> So far I used this hardware:  Intel Atom N330, N270, N510, IC2, AMD X2,
>> AMD Geode, VIA Eden
>>
>> regards,
>>
>> Felix
> I am running AMD X2 hardware with an ASUS motherboard.  My system would sync
> the time fairly quickly with kernels before 2.6.28 then it started syncing
> very slowly.  Some patches to the kernel where posted here that fixed this
> problem and these became part of the main line kernel starting with 2.6.30 (I
> think).  I am now running un-patched gentoo-sources 2.6.34 which I upgrade
> from 2.6.28 and it syncs quickly and is down below 5 us offsets in perhaps 15
> minutes give or take.
>
> The 2.6.34 kernel did introduce another timekeeping related issue for me
> however.  Starting with 2.6.32 the kernel was changed so that it requires a
> new kernel module to do hardware monitoring on some motherboards including
> mine.  Because of this I should now be using the ATK0110 module to get
> hardware readings using the ACPI interface (rather than lm_sensors directly
> poking the sensor hardware).  Without this module lm_sensors no longer works
> fully (no motherboard temperatures, voltages or fan speeds).  But with the
> ATK0110 module loaded ntp does not sync and time keeping is horrific.  I have
> opened a bug report on kernel.org about this but so far nothing has happened.
> Currently I do not have lm_sensors working fully on my machine.  My point is
> that how the kernel is configured and what modules you load can have a huge
> impact on time keeping and the ATK0110 module on MY HARDWARE is an example of
> this.  But it is also one I discovered by dumb luck and if I hadn't first had
> time keeping working nicely with 2.6.34 initially and then tried to fix the new
> lm_sensors problem I would not have known the cause of the timekeeping
> problem.  But it is clear that at least on some hardware the kernel ACPI
> modules can cause timekeeping issues and there may be other modules that
> impact timekeeping as well.
>
>>>> So my question is rather simple: Do you also have this problem?
>>> No... I did not measure time to get down to 0.00xxx but it is quick
>>> enough.
>>>
>>>> Which distribution did you use?
>>> Fedora. But I compile ntpd and kernel.org myself.
>>>
>>>> Which hardware is the best?
>>> What demands do you have for the precision?
>>>
>>> Udo
>>>
>>> _______________________________________________
>>> LinuxPPS mailing list
>>> LinuxPPS at ml.enneenne.com
>>> http://ml.enneenne.com/cgi-bin/mailman/listinfo/linuxpps
>>> Wiki: http://wiki.enneenne.com/index.php/LinuxPPS_support
>> _______________________________________________
>> LinuxPPS mailing list
>> LinuxPPS at ml.enneenne.com
>> http://ml.enneenne.com/cgi-bin/mailman/listinfo/linuxpps
>> Wiki: http://wiki.enneenne.com/index.php/LinuxPPS_support
>>
> _______________________________________________
> LinuxPPS mailing list
> LinuxPPS at ml.enneenne.com
> http://ml.enneenne.com/cgi-bin/mailman/listinfo/linuxpps
> Wiki: http://wiki.enneenne.com/index.php/LinuxPPS_support
>
>