Re: qemu hangs until a signal is delivered when running Fedora 14 i386 with -smp 2

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, 15 Oct 2010 17:35:18 +0200
Hans de Goede <hdegoede@xxxxxxxxxx> wrote:

> Hi All,
> 
> It took me a while to figure the below out, I hope it gives some clues
> into the problem I'm seeing. I'm running qemu compiled from git
> from the following repo:
> 
> http://cgit.freedesktop.org/spice/qemu/
> 
>  From the spice.v20 branch.
> 
> So this is basically qemu HEAD (not qemu-kvm but plain qemu), with spice
> patches added. I can reproduce this without the use of the spice vga device
> however!
> 
> When I start Fedora 14 i386 inside a qemu vm with the following cmdline:
> qemu-system-x86_64 -enable-kvm -cpu host \
>   -m 1024 -name F14 -smp 2 \
>   -drive file=/mnt/rhel6_x86_64/images/f14-i386.qcow2,if=virtio,media=disk \
>   -net nic,macaddr=52:54:00:7a:b4:7d,vlan=0,model=virtio,name=virtio.0 -net tap,vlan=0 \
>   -monitor stdio
> 
> And then:
> -wait till it has booted into gdm
> -switch to tty2 using sendkey ctrl+alt+f2 from the monitor
> -login as root
> -run the following:
>   while true; fortune; sleep 1; done;
> -wait (10 minutes or so at a maximum at my machine)
> -note qemu cpu load goes to 100% all of a sudden, monitor is dead,
>   ctrl+alt+1 to go to serial console is dead, guest is dead
> -attach a debugger, see it is executing guest instructions
>   (doing kvm_ioctl), also if you let it hang long enough you
>   will get BUG: soft lockup in dmesg (once you unstuck it)
> -detach, hang is gone everything works again, entered
>   monitor commands during the hang are executed, etc.
> 
> Alternatively sending SIGCHLD to the qemu process also unstucks qemu +
> the guest.

I've seen similar things on uniprocessor PowerPC, caused by a dyntick
timer not getting reprogrammed after expiring.  It went away when I
switched to using the I/O thread.

-Scott

--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux