Re: [Xen-users] Resolve "Time went backwards" problem by using jiffies as clocksource

[Daniel Lam <daniel@xxxxxxxxxxxxxxxx>]

On Mon, Jan 4, 2010 at 3:49 AM, Pasi Kärkkäinen <pasik@xxxxxx> wrote:

On Mon, Jan 04, 2010 at 03:44:34AM +1100, Daniel Lam wrote:
>    Hi All - so I guess nobody has the answers to these questions?
>    Is there somewhere I can ask, perhaps the developers list?
>

Have you tried using newer Xen hypervisor?
Xen 3.4.2 is the latest stable release.

Also, did you try different dom0/domU kernel versions?

-- Pasi

Thanks for prompt reply.

I *think* I have the latest stable version - I installed Xen by running

   apt-get install xen-linux-system-2.6.26-2-xen-686

on Debian 5.0 Lenny. And no I haven't tried different dom0/domU

kernel versions. I have only been playing around with Debian 5.0 Lenny, 

as dom0 and domU.

Are you suggesting that using xen as clocksource should work

on latest stable versions?

And for the record I'm experimenting on a Dell Optiplex GX520 with 2gb ram.

Daniel

>    Daniel

>    ---------- Forwarded message ----------
>    From: Daniel Lam <[1]daniel@xxxxxxxxxxxxxxxx>
>    To: [2]xen-users@xxxxxxxxxxxxxxxxxxx
>    Date: Sat, 2 Jan 2010 17:20:12 +1100
>    Subject: [Xen-users] Resolve "Time went backwards" problem by using
>    jiffies as clocksource
>    Hi All,
>    I'm new to Xen and... Happy New Year!
>    After restarting dom-0, my dom-u prints this in console once every second,
>    [55082.616234] __ratelimit: 1503 messages suppressed
>    [55082.616234] clocksource/0: Time went backwards: ret=380ab26c53a
>    I resolved this by following the instructions in

>    "[3]http://wiki.debian.org/Xen",

>    which is basically changing clocksource to "jiffies".
>    Now the problem has gone away, I'm wondering if somebody can help me:
>    1. Is domain-0 not able to set the system time of domain-u the root cause?
>        I can see this error in console "Unable to set System Clock to: <a
>    datetime value>",
>        even after I changed clocksource to "jiffies".
>    2. Why can't domain-0 set the date of the domain-u?
>    3. If this is the only way to go (using jiffies clocksource), I will have
>    to sync
>        the domain-u system time manually using something like ntpd?
>    Thanks!
>    cheers,
>    Daniel
>

> References
>
>    Visible links
>    1. mailto:daniel@xxxxxxxxxxxxxxxx
>    2. mailto:xen-users@xxxxxxxxxxxxxxxxxxx
>    3. http://wiki.debian.org/Xen

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