[Bug 1318830] Re: High CPU usage on windows virtual machine

[Boyan Stoyanovich]

I have this problem also using Debian Wheezy with backported qemu-
kvm-2.0.0, CPU usage for idle Windows machine ,using top to measure ,is
constantly >30% (while in Windows Task Manager >5%), while Linux VM
beside is working fine (CPU >5%) when idle...

Here are the details about packages used and qemu-kvm process:

root at bojan:~# uname -a
Linux bojan 3.2.0-4-amd64 #1 SMP Debian 3.2.60-1+deb7u1 x86_64 GNU/Linux
root at bojan:~# dpkg -l | egrep '(qemu|kvm|spice)'
ii  ipxe-qemu                             1.0.0+git-20120202.f6840ba-3       all          PXE boot firmware - ROM images for qemu
ii  libspice-client-glib-2.0-1:amd64      0.12-5                             amd64        GObject for communicating with Spice servers (runtime library)
ii  libspice-client-gtk-2.0-1:amd64       0.12-5                             amd64        GTK2 widget for SPICE clients (runtime library)
ii  libspice-server1:amd64                0.12.4-0nocelt2~bpo70+1            amd64        Implements the server side of the SPICE protocol
ii  python-spice-client-gtk               0.12-5                             amd64        GTK2 widget for SPICE clients (Python binding)
ii  qemu-keymaps                          1.1.2+dfsg-6a+deb7u3               all          QEMU keyboard maps
ii  qemu-kvm                              2.0.0+dfsg-4~bpo70+1               amd64        QEMU Full virtualization on x86 hardware (transitional package)
rc  qemu-system                           2.0.0+dfsg-4~bpo70+1               amd64        QEMU full system emulation binaries
ii  qemu-system-common                    2.0.0+dfsg-4~bpo70+1               amd64        QEMU full system emulation binaries (common files)
ii  qemu-system-x86                       2.0.0+dfsg-4~bpo70+1               amd64        QEMU full system emulation binaries (x86)
ii  qemu-utils                            2.0.0+dfsg-4~bpo70+1               amd64        QEMU utilities

115      18212 36.1 35.4 2727568 2154604 ?     Sl   10:07   4:08 qemu-
system-x86_64 -enable-kvm -name Win7ENTx64 -S -machine pc-
i440fx-2.0,accel=kvm,usb=off -cpu
SandyBridge,+erms,+smep,+fsgsbase,+rdrand,+f16c,+osxsave,+pcid,+pdcm,+xtpr,+tm2,+est,+vmx,+ds_cpl,+monitor,+dtes64,+pbe,+tm,+ht,+ss,+acpi,+ds,+vme
-m 2048 -realtime mlock=off -smp 2,sockets=2,cores=1,threads=1 -uuid
c1be1529-83e4-82f1-5277-d82cb0e853b4 -no-user-config -nodefaults
-chardev
socket,id=charmonitor,path=/var/lib/libvirt/qemu/Win7ENTx64.monitor,server,nowait
-mon chardev=charmonitor,id=monitor,mode=control -rtc base=localtime
-no-shutdown -boot strict=on -device piix3-usb-
uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device virtio-serial-pci,id=virtio-
serial0,bus=pci.0,addr=0x7 -drive
file=/var/lib/libvirt/images/Win7ENTx64.qcow2,if=none,id=drive-virtio-
disk0,format=qcow2 -device virtio-blk-
pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-
disk0,bootindex=1 -drive
file=/var/lib/libvirt/images/Microsoft_Windows_7_Enterprise_x64_SP1.ISO,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 -netdev
tap,fd=25,id=hostnet0,vhost=on,vhostfd=26 -device virtio-net-
pci,netdev=hostnet0,id=net0,mac=52:54:00:ac:2b:78,bus=pci.0,addr=0x3
-chardev pty,id=charserial0 -device isa-
serial,chardev=charserial0,id=serial0 -chardev
spicevmc,id=charchannel0,name=vdagent -device virtserialport,bus=virtio-
serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0
-device usb-tablet,id=input0 -spice port=5901,addr=127.0.0.1,disable-
ticketing,seamless-migration=on -device VGA,id=video0,bus=pci.0,addr=0x2
-device intel-hda,id=sound0,bus=pci.0,addr=0x4 -device hda-
duplex,id=sound0-codec0,bus=sound0.0,cad=0 -device virtio-balloon-
pci,id=balloon0,bus=pci.0,addr=0x6

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Title:
  High CPU usage on windows virtual machine

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