[Voyage-linux] Re: Voyage 0.5.2 time sync issue

[Panagiotis Malakoudis]

I also had the same time problem on an alix board with voyage 0.6.1 kernel.
After some investigation, the problem was actually the usage of the
geode-mfgpt timers. geode-mfgpt provides two clock sources, tsc and the
default jiffies. tsc is reported unstable and jiffies is selected (you can
see that by issuing the command  cat
/sys/devices/system/clocksource/clocksource0/available_clocksource and  cat
/sys/devices/system/clocksource/clocksource0/current_clocksource). jiffies
clocksource is well known to be inacurate and losing time sync. I solved the
problem by disabling geode-mfgpt timers (by adding nomfgpt in the kernel
cmdline options). After that, pit is selected as clocksource and I have no
timer issues.

I guess a newer kernel build (like the mentioned 2.6.27) might fix the
geode-mfgpt tsc clocksource reported as unstable, thus eliminating the timer
problem.

Hope this helps

On Thu, Apr 2, 2009 at 12:46 AM, Alexander Krsek <merlin at gremlin.cz> wrote:

> Stéphane Acounis <stephane.acounis at ...> writes:
>
> >
> > Le Tue, 31 Mar 2009 21:21:25 -0500
> > Sam <voyage at ...> a écrit:
> >
> > > I don't know what hardware you are using but ntp won't work on the
> > > alix boards as their time skew is beyond the limits allowed in ntp.
> > > Just running ntpdate with cron every hour or so usually works better
> > > (if hardware is the issue).
> > >
> > > Sam
> >
> > Hi,
> >
> > I'm using Voyage 0.5.2 on an Alix3c2 board.
> >
> > ntpq -p
> >      remote           refid      st t when poll reach   delay   offset
> >      jitter
> >
>
> ==============================================================================
> >      LOCAL(0)        .LOCL.          10 l   57   64  377    0.000
> >      0.000   0.015 *192.168.0.1     134.158.24.1     7 u   30   64
> >      377    0.262    0.049   0.194
> >
> > uptime:
> > 09:54:02 up 6 days, 17:17,  2 users,  load average: 0.00, 0.01, 0.00
> >
> > The NTP server is broadcasting time he has received from the network.
> >
> > So ntp is working on Alix boards.
> >
>
> It depends.
>
> I had same problem with voyage 0.6.1 (distribution kernel 2.6.26) on Alix
> 2D3
> board. Time skew was like one second less every 20 seconds.
>
> I solved it with adjtimex package, which quite fixed constant time skew and
> then run ntpd on top of that.
>
> Interesting is, that with (self configured/compiled) 2.6.27 kernel there is
> no
> such issue. Also some time ago, voyage 0.5.2 (with distribution kernel) did
> not
> have any such problem with ntpd on that board.
>
> So yes, ntp is working on Alix boards. And most of time without any other
> help ;)
>
>
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>
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