From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paul <flypen@gmail.com>
Subject: Re: A non-responsive guest problem
Date: Wed, 24 Aug 2011 20:47:54 +0800
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Cc: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>, kvm@vger.kernel.org,
	Avi Kivity <avi@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
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Hi,

Sometimes this problem happened in one day, but sometimes it was very
difficult to reproduce it.
Previously the clock source of the guest was kvm-clock. Now I changed
it to tsc. The problem didn't occur until now. Is it related to the
clock source? I  find that there are some bug fixes for kvm-clock
recently. (e.g.,
http://www.spinics.net/lists/stable-commits/msg11942.html) Anyway, I
will update KVM later.

Thanks,
Paul

On Wed, Aug 24, 2011 at 6:24 PM, Stefan Hajnoczi <stefanha@gmail.com> w=
rote:
>
> On Wed, Aug 24, 2011 at 10:02 AM, Xiao Guangrong
> <xiaoguangrong@cn.fujitsu.com> wrote:
> > On 08/24/2011 04:40 PM, Paul wrote:
> >> Hi,
> >>
> >> I captured the output of pidstat when the problem was reproduced:
> >>
> >> bash-4.1# pidstat -p $PID 8966
> >> Linux 2.6.32-71.el6.x86_64 (test) =A0 =A0 07/24/11 =A0 =A0 =A0 =A0=
_x86_64_ =A0 =A0 =A0 =A0(4 CPU)
> >>
> >> 16:25:15 =A0 =A0 =A0 =A0 =A0PID =A0 =A0%usr %system =A0%guest =A0 =
=A0%CPU =A0 CPU =A0Command
> >> 16:25:15 =A0 =A0 =A0 =A0 8966 =A0 =A00.14 =A0 55.04 =A0115.41 =A01=
70.59 =A0 =A0 1 =A0qemu-kvm
> >>
> >
> > I have tried to reproduce it, but it was failed. I am using the
> > current KVM code. I suggest you to test it by the new code if possi=
ble.
>
> Yes, that's a good idea. =A0The issue might already be fixed. =A0But =
if
> this is hard to reproduce then perhaps keep the spinning guest around
> a bit longer so we can poke at it and figure out what is happening.
>
> The pidstat output shows us that it's the guest that is spinning, not
> qemu-kvm userspace.
>
> The system time (time spent in host kernel) is also quite high so
> running kvm_stat might show some interesting KVM events happening.
>
> Stefan