[Voyage-linux] Clock Drift

Wed Sep 1 04:38:25 HKT 2010

Just to chime in here:

I followed the VMWare clock kernel parameter recommendations for
Debian 4x and set:
divider=10 clocksource=acpi_pm

No go.  Tried clocksource=tsc, after about 5 hours, it was a good 15
or 16 minutes behind my NTP server.

I also noticed at shutdown, adjtime was complaining about a read-only
filesystem when trying to write to /etc/adjtime so I symlinked that
file to /tmp/adjtime.

Still no improvement.

Does anyone have a fix that works reliably?  This is going to be used
as a Snort sensor and obviously the Syslog alerts need to be as
accurate as possible.

2010/8/27 Roel H <lists at rulus.be>:
> Hello Robert,
>
>
> Recently I made a patch to the kernel to use a 1024 Hz timer
> frequency, based on the messages in this thread. This seems to
> work well on the 2D2 board I have here. The clock is very stable
> without ntp or adjtimex.
>
> You can find my build of the 2.6.32-17 kernel at [1]. This is the
> pure upstream kernel with added aufs and the 1024 Hz kernel
> frequency (in the -geode image). So best use the -geode image on
> the Alix.
>
> Being a custom built upstream kernel it might not have all the
> functionality you need, or break other things, but maybe it's
> usefull to try whether the clock is any more stable.
>
> If it's the case you might be able to patch the Voyage kernel
> instead.
>
> [1] http://zeus.ugent.be/~rulus/archive/experimental/experimental/
>
> Kind regards,
>
> Roel
>
> Reply on message from Robert <Robert at supporttime.com>
> received Thu 26 Aug 2010 18:41 +0200:
>> Hello Guys,
>>
>> I hope you're all well. I've been trying to resolve the clock
>> drift issues again today and I'm struggling.
>>
>> I cannot use the 'nomfgpt' work around as we rely on the
>> watchdog and doing so breaks it.
>>
>> I have installed adjtimex and ntp:
>>
>> apt-get install adjtimex
>> apt-get install ntp
>>
>> Which I thought may solve the issue as some others have
>> suggested but even with this the clock still drifts wildly, and
>> after just a couple of hours the clock is already several
>> minutes out of sync.
>>
>> Can anyone offer any other advice? I could always schedule a
>> cron task to correct the clock but that seems so hacky.
>>
>> Thanks,
>>
>> Robert
>>
>> On 11/06/2010 03:28, "Darryl Ross" <spam at afoyi.com> wrote:
>>
>> Really old thread, but wanted to say thanks, this has fixed the same
>> problem I was having on 2x Alix2-3 systems.
>>
>>
>>
>> Robert wrote:
>> > Hi Jordi,
>> >
>> >
>> >
>> > That's a great help, thank you! I'll give that a go and see how I get on :-D
>> >
>> >
>> >
>> > Your wFrog sounds like an interesting project, do you do much work with
>> > Thermometers and Hygrometer hardware? If so I've got a little pet
>> > project on the go which I'd be interested to talk with you about! :-D
>> >
>> >
>> >
>> > Rob
>> >
>> >
>> >
>> > *From:* Jordi Puigsegur [mailto:jordi.puigsegur at gmail.com]
>> > *Sent:* 26 February 2010 10:26
>> > *To:* Robert
>> > *Cc:* voyage-linux at list.voyage.hk
>> > *Subject:* Re: [Voyage-linux] Clock Drift
>> >
>> >
>> >
>> > I run into the same problems a couple of weeks ago. First I tried
>> > disabling mfgpt and it solved the problem but left the watchdog driver
>> > not funcional. Later on I undid this change, activated again mfgpt and
>> > installed adjtimex and ntp. My system is now working in perfect sync.
>> >
>> > I've described this configuration in a wiki
>> > (http://code.google.com/p/wfrog/wiki/InstallOn_Alix3D2_voyageLinux0_6_2#Clock_sync).
>> > wfrog is the open source weather logger I'm running on the Alix 3D2.
>> >
>> > Hope it helps!
>> >
>> > Jordi.
>> >
>> > 2010/2/26 Robert <Robert at supporttime.com <mailto:Robert at supporttime.com>>
>> >
>> > Hey Punky,
>> >
>> > Thanks for getting back to me. So you're saying I have a choice between
>> > a working clock or a working watchdog, I can't have both?
>> >
>> > Robert
>> >
>> >
>> > -----Original Message-----
>> > From: Punky Tse [mailto:punkytse at punknix.com <mailto:punkytse at punknix.com>]
>> > Sent: 26 February 2010 02:48
>> > To: Robert
>> > Cc: 'voyage-linux at list.voyage.hk <mailto:voyage-linux at list.voyage.hk>'
>> > Subject: Re: [Voyage-linux] Clock Drift
>> >
>> > Hi Robert,
>> >
>> > Disabling mfgpt will make geode watchdog driver no functional.
>> > [   22.373287] geodewdt:  No timers were available
>> >
>> > Regards,
>> > Punky
>> >
>> > Robert wrote:
>> >> Hi Punky, Thierry,
>> >>
>> >> Thanks very much for that suggestion. Tell me, is there any downside
>> > to adding that boot parameter? is it likely to cause me other issues?
>> >>
>> >> Many thanks,
>> >>
>> >> Rob
>> >> ________________________________________
>> >> From: voyage-linux-bounces+robert=supporttime.com
>> > <http://supporttime.com>@list.voyage.hk <http://list.voyage.hk>
>> > [voyage-linux-bounces+robert=supporttime.com
>> > <http://supporttime.com>@list.voyage.hk <http://list.voyage.hk>] On
>> > Behalf Of Thierry MUSEUX - www.fwt.fr <http://www.fwt.fr> - [tm at fwt.fr
>> > <mailto:tm at fwt.fr>]
>> >> Sent: 25 February 2010 16:58
>> >> To: 'voyage-linux at list.voyage.hk <mailto:voyage-linux at list.voyage.hk>'
>> >> Subject: RE: [Voyage-linux] Clock Drift
>> >>
>> >> Hi,
>> >>
>> >> I have put in /boot/grub/menu.lst
>> >> kernel /vmlinuz root=LABEL=ROOT_FS  console=ttyS0,38400n8 nomfgpt
>> >>
>> >> and in /etc/crontab
>> >> 15 * * * * root /usr/sbin/ntpdate 0.fr.pool.ntp.org
>> > <http://0.fr.pool.ntp.org> >> /dev/null 2>&1
>> >>
>> >> This solve the issue.
>> >>
>> >>
>> >> Thierry Museux
>> >> France Wireless Technologies
>> >> www.fwt.fr <http://www.fwt.fr>
>> >> msn: tm at fwt.fr <mailto:tm at fwt.fr>
>> >> Tel: + 33 (0) 1 41 08 70 78
>> >> Gsm: + 33 (0) 6 15 22 09 62
>> >>
>> >>
>> >>
>> >>
>> >> -----Message d'origine-----
>> >> De : voyage-linux-bounces+tm=fwt.fr <http://fwt.fr>@list.voyage.hk
>> > <http://list.voyage.hk>
>> >> [mailto:voyage-linux-bounces+tm
>> > <mailto:voyage-linux-bounces%2Btm>=fwt.fr <http://fwt.fr>@list.voyage.hk
>> > <http://list.voyage.hk>] De la part de Roel
>> >> Huybrechts
>> >> Envoyé : jeudi 25 février 2010 17:40
>> >> À : Robert
>> >> Cc : voyage-linux at list.voyage.hk <mailto:voyage-linux at list.voyage.hk>
>> >> Objet : Re: [Voyage-linux] Clock Drift
>> >>
>> >> Hi Rob,
>> >>
>> >> Op donderdag 25-02-2010 om 08:26 uur [tijdzone -0800], schreef Robert:
>> >>
>> >>> Hello Guys,
>> >>>
>> >>> I've got some pretty serious clock drift on all the ALIX 3d2 which we've
>> >>>
>> >> got. Seems that after even just a short period of running the time on the
>> >> systems is quite out of sync with the real time.
>> >>
>> >>> Is this a common issue? We've had it for a long time but I've only
>> >>>
>> >> recently sat down and tried to find a solution to the problem. Is this
>> >> hardware related? or something software related?
>> >>
>> >>> Appreciate any advice you can offer.
>> >>>
>> >>> Rob
>> >>>
>> >>
>> >> I've experienced the same issue on the ALIX 2d2 boards here. I've been
>> >> able to greatly reduce the drift by installing the adjtimex package.
>> >>
>> >> Hope this helps for you as well.
>> >>
>> >> Regards
>> >>
>> >> --
>> >> Roel Huybrechts
>> >>
>> >> GPG  | 4096R/5E2DE374
>> >>      | http://rulus.be/gpg
>> >>
>> >>
>> >> _______________________________________________
>> >> Voyage-linux mailing list
>> >> Voyage-linux at list.voyage.hk <mailto:Voyage-linux at list.voyage.hk>
>> >> http://list.voyage.hk/mailman/listinfo/voyage-linux
>> >>
>> >> Support Time Managed Services - monitoring and development for entire
>> > business technology
>> >>
>> >> Tel: 0800 999 4333
>> >> www.supporttime.com <http://www.supporttime.com>
>> >>
>> >> Support Time Limited
>> >> 1000 Lakeside North Harbour
>> >> Portsmouth PO6 3EZ United Kingdom
>> >>
>> >> _______________________________________________
>> >> Voyage-linux mailing list
>> >> Voyage-linux at list.voyage.hk <mailto:Voyage-linux at list.voyage.hk>
>> >> http://list.voyage.hk/mailman/listinfo/voyage-linux
>> >>
>> >
>> >
>> > Support Time Managed Services - monitoring and development for entire
>> > business technology
>> >
>> > Tel: 0800 999 4333
>> > www.supporttime.com <http://www.supporttime.com>
>> >
>> > Support Time Limited
>> > 1000 Lakeside North Harbour
>> > Portsmouth PO6 3EZ United Kingdom
>> >
>> > _______________________________________________
>> > Voyage-linux mailing list
>> > Voyage-linux at list.voyage.hk <mailto:Voyage-linux at list.voyage.hk>
>> > http://list.voyage.hk/mailman/listinfo/voyage-linux
>> >
>> >
>> >
>> >
>> > ------------------------------------------------------------------------
>> > Support Time Managed Services - monitoring and development for entire
>> > business technology
>> >
>> > Tel: 0800 999 4333
>> > www.supporttime.com
>> >
>> > Support Time Limited
>> > 1000 Lakeside North Harbour
>> > Portsmouth PO6 3EZ United Kingdom
>> >
>> >
>> > ------------------------------------------------------------------------
>> >
>> > _______________________________________________
>> > Voyage-linux mailing list
>> > Voyage-linux at list.voyage.hk
>> > http://list.voyage.hk/mailman/listinfo/voyage-linux
>>
>>
>
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>
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