Re: [Qemu-devel] BUG: RTC issue when Windows guest is idle

[mdroth]

On Thu, Feb 21, 2013 at 06:16:10PM +0000, Matthew Anderson wrote:
> If this isn't the correct list just let me know,
> 
> I've run into a bug whereby a Windows guest (tested on Server 2008R2 and 
> 2012) no longer receives RTC ticks when it has been idle for a random amount 
> of time. HPET is disabled and the guest is running Hyper-V relaxed timers 
> (same situation without hv_relaxed). The guest clock stands still and the 
> qemu process uses very little CPU (<0.5%, normally it's >5% when the guest is 
> idle) . Eventually the guest stops responding to network requests but if you 
> open the guest console via VNC and move the mouse around it comes back to 
> life and QEMU replays the lost RTC ticks and the guest recovers. I've also 
> been able to make it recover by querying the clock over the network via the 
> net time command, you can see the clock stand still for 30 seconds then it 
> replays the ticks and catches up.
> 
> I've tried to reproduce the issue but it seems fairly illusive, the only way 
> I've been able to reproduce it is by letting the VM's idle and waiting. 
> Sometimes it's hours and sometimes minutes. Can anyone suggest a way to 
> narrow the issue down?
> 
> Qemu command line is-
> /usr/bin/kvm -name SQL01 -S -M pc-0.14 -cpu qemu64,hv_relaxed -enable-kvm -m 
> 2048 -smp 2,sockets=2,cores=1,threads=1 -uuid 
> 5f54333b-c250-aa72-c979-39d156814b85 -no-user-config -nodefaults -chardev 
> socket,id=charmonitor,path=/var/lib/libvirt/qemu/iHost-SQL01.monitor,server,nowait
>  -mon chardev=charmonitor,id=monitor,mode=control -rtc base=localtime 
> -no-hpet -no-shutdown -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 
> -drive 
> file=/mnt/gluster1-norep/iHost/SQL01.qed,if=none,id=drive-virtio-disk0,format=qed,cache=writeback
>  -device 
> virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0
>  -drive 
> file=/mnt/gluster1-norep/iHost/SQL01-Data.qed,if=none,id=drive-virtio-disk2,format=qed,cache=writeback
>  -device 
> virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=drive-virtio-disk2,id=virtio-disk2
>  -drive if=none,id=drive-ide0-1-0,readonly=on,format=raw -device 
> ide-cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0,bootindex=1 -netdev 
> tap,fd=29,id=hostnet0,vhost=on,vhostfd=39 -device 
> virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:2c:8d:23,bus=pci.0,addr=0x3
>  -chardev pty,id=charserial0 -device 
> isa-serial,chardev=charserial0,id=serial0 -device usb-tablet,id=input0 -vnc 
> 127.0.0.1:22 -vga cirrus -device 
> virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4
> 
> Environment is -
> Mainline 3.7.5 and 3.8.0
> Qemu 1.2.2, 1.3.1 and 1.4.0

Were all of these with -M pc-0.14? Only thing that stands out to me is
kernel_irqchip being disabled in your case. -M 1.1 and higher will
enable it by default. Worth a shot.

> Scientific Linux 6.3
> KSM enabled, transparent hugepages disabled.
> Dual Xeon 5650
> 192GB
> 
> Thanks all
>