End-User Question: XP-Guest produces high load for no obvious reason

[Andre Tann <atann@alphasrv.net>]

Hello everyone,

I'm not sure if this is the correct mailing list with my topic. But the
website says that end user's questions are welcome. So please give me a
hint if this is the wrong place.


On the host:

# rpm -qa | grep kvm
kvm-0.12.5-1.2.1.x86_64

# uname -a
Linux alphawkst 2.6.34.7-0.7-desktop #1 SMP PREEMPT 2010-12-13 11:13:53
+0100 x86_64 x86_64 x86_64 GNU/Linux



The guest is a Windows XP 32 Bit, and everything was fine until
yesterday. For no obvious reason, as soon as the guest starts one of the
two cpu cores has 100% load if started with -smp 1, and both cpu cores
have 100% load if started with -smp 2. There is no process inside the
guest that generates this load. Instead, the guest is idling at 0-5%
(that's what the windows task manager gives in the status line).


The guest is started with:

# qemu-kvm -M pc-0.12 -enable-kvm -smp 2 -m 1024 -name XP2Use -uuid
ad148b2d-b99e-c9de-7c0c-4ab6b716f3ec -rtc base=localtime -boot c -drive
file=/var/lib/libvirt/images/XP2Use.img,if=ide,index=0,boot=on,format=raw,cache=unsafe
-net nic,model=rtl8139,vlan=0,macaddr=52:54:00:5d:a2:a5 -net tap -vnc
127.0.0.1:0 -k de -vga std -usbdevice tablet


The same happens if the machine is started via virt-manager, in which
case I find the following in the process list:

# ps aux | grep qemu
root     12909  100 13.1 1231668 1076428 ?     Sl   12:36   0:20
/usr/bin/qemu-kvm -S -M pc-0.12 -enable-kvm -m 1024 -smp
1,sockets=1,cores=1,threads=1 -name XP2Use -uuid
ad148b2d-b99e-c9de-7c0c-4ab6b716f3ec -nodefaults -chardev
socket,id=monitor,path=/var/lib/libvirt/qemu/XP2Use.monitor,server,nowait
-mon chardev=monitor,mode=readline -rtc base=localtime -boot dc -drive
if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw -device
ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -drive
file=/var/lib/libvirt/images/XP2Use.img,if=none,id=drive-
ide0-0-0,boot=on,format=raw
-device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0
-device rtl8139,vlan=0,id=net0,mac=52:54:00:5d:a2:a5,bus=pci.0,addr=0x4
-net tap,fd=38,vlan=0,name=hostnet0 -chardev pty,id=serial0 -device
isa-serial,chardev=serial0 -usb -device usb-tablet,id=input0 -vnc
127.0.0.1:0 -k en-us -vga std -device virtio-balloon-
pci,id=balloon0,bus=pci.0,addr=0x3


Can anyone see a reason for this behavior?


And again, if I'm wrong here, please point me to the right place.

Thanks!

-- 
Andre Tann