From: Marcelo Tosatti <mtosatti@redhat.com>
To: Dale Swanston <swanston@sedsystems.ca>
Cc: kvm@vger.kernel.org
Subject: Re: setting time in guest with ntpdate results in VM hang
Date: Fri, 24 Aug 2012 16:43:45 -0300 [thread overview]
Message-ID: <20120824194345.GA16662@amt.cnet> (raw)
In-Reply-To: <5037A46F.7050104@sedsystems.ca>
On Fri, Aug 24, 2012 at 09:57:35AM -0600, Dale Swanston wrote:
> Hello.
>
> We are running a guest OS of CentOS 4.4 (kernel 2.6.12) for legacy
> reasons, upgrading is not an option. NTP is running on the host
> and synching with a local GPS NTP server. But due to frequency
> drift in the guest it restarts itself periodically and upon start up
> performs an ntpdate to force a time jump on the guest.
>
> I have seen 2 occasions now (over 2 months) where the VM hangs right
> as the ntpdate command alters the guest clock (based on output in
> /var/log/messages).
>
> From the host's perspective the VM is still running but it appears
> to be using very high CPU percentage (more than typical). The only
> recovery option is to force shutdown of the VM and restart it.
This should not happen.
> 1. Are there any known issues with ntpdate and VMs hanging? Any
> workarounds?
> 2. Are there any debugging tools further characterise the problem?
Upgrading the guest kernel is not an option? At least install recent
kernel in guest to confirm that its not an already fixed bug.
> Thanks in advance,
> Dale
>
>
> Further specifics, let me know if more details are needed:
>
> Host:
> # uname -a
> Linux s1pscu01host 2.6.32-220.el6.x86_64 #1 SMP Sat Dec 10 17:04:11
> CST 2011 x86_64 x86_64 x86_64 GNU/Linux
>
> on Intel(R) Xeon(R) CPU E5620 @ 2.40GHz
>
> with qemu-kvm-0.12.1.2-2.209.el6.x86_64
>
> Guest:
> I don't use any kernel time modifiers in the guest ...
> kernel /vmlinuz-2.6.12 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
>
> CentOS 4.4
> --
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next prev parent reply other threads:[~2012-08-24 20:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-24 15:57 setting time in guest with ntpdate results in VM hang Dale Swanston
2012-08-24 19:43 ` Marcelo Tosatti [this message]
2012-08-27 16:58 ` Dale Swanston
2012-08-27 19:23 ` David Ahern
2012-08-27 19:51 ` Marcelo Tosatti
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