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Date: Wed, 4 Jul 2012 23:02:51 -0300
From: Marcelo Tosatti <mtosatti@redhat.com>
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References: <4FEAE1EA.3070107@dlh.net> <20120703155430.GA21571@amt.cnet>
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Subject: Re: [Qemu-devel] race condition in qemu-kvm-1.0.1
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To: Peter Lieven <pl@dlhnet.de>
Cc: Peter Lieven <pl@dlh.net>, qemu-devel@nongnu.org, kvm@vger.kernel.org

On Wed, Jul 04, 2012 at 12:03:58PM +0200, Peter Lieven wrote:
> On 07/03/12 17:54, Marcelo Tosatti wrote:
> >On Wed, Jun 27, 2012 at 12:35:22PM +0200, Peter Lieven wrote:
> >>Hi,
> >>
> >>we recently came across multiple VMs racing and stopping working. It
> >>seems to happen when the system is at 100% cpu.
> >>One way to reproduce this is:
> >>qemu-kvm-1.0.1 with vnc-thread enabled
> >>
> >>cmdline (or similar):
> >>/usr/bin/qemu-kvm-1.0.1 -net
> >>tap,vlan=141,script=no,downscript=no,ifname=tap15,vnet_hdr -net
> >>nic,vlan=141,model=virtio,macaddr=52:54:00:ff:00:f7 -drive format=host_device,file=/dev/mapper/iqn.2001-05.com.equallogic:0-8a0906-efdf4e007-16700198c7f4fead-02-debug-race-hd01,if=virtio,cache=none,aio=native
> >>-m 2048 -smp 2,sockets=1,cores=2,threads=1 -monitor
> >>tcp:0:4026,server,nowait -vnc :26 -qmp tcp:0:3026,server,nowait
> >>-name 02-debug-race -boot order=dc,menu=off -cdrom
> >>/home/kvm/cdrom//root/ubuntu-12.04-server-amd64.iso -k de -pidfile
> >>/var/run/qemu/vm-221.pid -mem-prealloc -cpu
> >>host,+x2apic,model_id=Intel(R) Xeon(R) CPU           L5640  @
> >>2.27GHz,-tsc -rtc base=utc -usb -usbdevice tablet -no-hpet -vga
> >>cirrus
> >Is it reproducible without vnc thread enabled?
> Yes, it is. I tried it with and without. It is also even happnig
> with 0.12.5 where
> no vnc thread (and i think also iothread) is available.

Do you have traces without vnc-thread enabled?